Glioblastoma and Treatment Options

What is Glioblastoma?

Glioblastoma (GBM) is one of the deadliest cancers that can develop quickly through primary, de novo tumors, or slowly through secondary tumors that were already present. There are four subtypes which include classical, mesenchymal, proneural, and neural. The difference between these depends on the amplification or mutation of specific genes that are present [1]. Furthermore, an article by Fung et al., depicts how the expression of matrix-metalloproteinases (MMPs) and the PI3K pathway contribute to the invasiveness of these tumors due to their role in promoting invadopodia (2019). Other signaling pathways like the MAPK pathway along with the PI3K pathway play roles in cell proliferation and cell survival. However, in GBM, these pathways are amplified due to the deletion of tumor suppressors like NF1 or PTEN or cross talk between the pathways. Specifically, Akt and ERK play a role in phosphorylation of other pathways. This makes different signaling pathways such as the PI3K, MAPK, and cAMP pathways a possible therapeutic target in the future [1]. Little advances have been made on treatment of such aggressive forms of cancer, however, leaving traditional treatment like radiation and chemotherapy as some of the only options.

How does chemotherapy work?

Chemotherapy consists of drugs that circulate the bloodstream to kill or shrink cancer cells. This form of therapy is considered systematic because it travels through the whole body, leaving the possibility of healthy cells being targeted as well. These drugs can be delivered via IV, orally, or injection and are often administered in cycles. They may be plant derived or synthetic and include different combinations of chemicals depending on the goals of treatment (Figure 1) [2]. Common side effects from this treatment option are feelings of fatigue, hair loss, decreased blood count, and nausea [3].

Figure 1. Possible agents in chemotherapy drugs [4].

What is radiation?

Radiation is essentially bursts of energy that go through the skin to break up the DNA inside cancer cells to stop or decrease growth. It is termed “local” because it only treats the area where the cancer cells reside. There are multiple different delivery methods with the most common being external, displayed in figure 2. In this method, the individual is put into a machine that shoots high-energy beams into the body. Other delivery methods include internally, when radioactive seeds are placed inside to body, or systematic when a pill or needle are utilized [2]. Radiation typically causes less damage to the whole body if delivered externally because of the localization [4]. Side effects may still occur such as tiredness and stiffness, hair loss, diarrhea, and changes to the skin where the radiation has penetrated [3].

Figure 2. Chemotherapy and radiation comparison [6].

Chemotherapy or radiation?

Overall, GBM is a very aggressive cancer that must continue to be studied to find specific treatments. Advances have been made in learning the role of multiple signaling pathways such as the PI3K, MAPK, and cAMP pathways and their communication with each other. However, it is yet to be discovered how to utilize this information in treatment. For this reason, chemotherapy and radiation continue to be widely used if surgery is not an option. While chemotherapy may be more harmful to the whole body, typically, using a combination of treatments increases the chances of success. However, treatment will always be personalized depending on the form of cancer, the stage, and personal preferences.

References

[1] Fung, N. H., Grima, C. A., Widodo, S. S., Kaye, A. H., Whitehead, C. A., Stylli, S. S., & Mantamadiotis, T. (2019). Understanding and exploiting cell signalling convergence nodes and pathway cross-talk in malignant brain cancer. Cellular Signalling, 57, 2–9. https://doi.org/10.1016/j.cellsig.2019.01.011

[2] What’s the Difference Between Chemotherapy and Radiation? (n.d.). Retrieved April 23, 2024, from https://www.webmd.com/cancer/cancer-chemotherapy-radiation-differences

[3] Chemo Vs Radiation Therapy: Differences, Side Effects | SERO. (2022, December 9). https://treatcancer.com/blog/difference-chemotherapy-radiation/

[4] Bukowski, K., Kciuk, M., & Kontek, R. (2020). Mechanisms of Multidrug Resistance in Cancer Chemotherapy. International Journal of Molecular Sciences, 21(9), Article 9. https://doi.org/10.3390/ijms21093233

[5] How Radiation Therapy Is Used to Treat Cancer. (n.d.). Retrieved April 23, 2024, from https://www.cancer.org/cancer/managing-cancer/treatment-types/radiation/basics.html

[6] Chemotherapy vs. Radiation for Lung Cancer. (n.d.). Verywell Health. Retrieved April 23, 2024, from https://www.verywellhealth.com/chemotherapy-vs-radiation-for-lung-cancer-5219436

Make Room For Headspace!

Why do I personally enjoy this topic? Maybe because of my unknown personal connection to it? Traumatic brain injury (TBI) is usually caused by a mechanical impact on the head. This injury is usually followed by symptoms such as slow cognition, migraines, dizziness, and weakness. Young children may be at higher risks of having a TBI due to their involvement in sports. But most research have pointed out that after prevention, recovery time might hold a big key in restoring the health of a TBI patient. Therefore, due to the high risk TBI poses to younger people, recent research has looked into understanding the impact of TBI on a molecular level. 

Figure 1. Picture showing events that follow occurence of a TBI in the brain. Symptoms usually emerge from these events.

Research has shown that on a molecular scale, mechanical impact on the brain can lead to events such as neuroinflammation and axonal dysfuntion. In simpler terms, inflammation is the body’s response to injuries whereby chemicals are released to the site of an injury. Neuroinflammation is when inflammation happens in the CNS: brain or spinal cord. More importantly, significant imaging techniques such as Diffusion Tensor Imaging (DTI) [2] and Fractional anisotropy (FA)  [3].

While FA  serves as a sclae to understand levels of damage to white matter and axons after a TBI, researchers and physicians are able to gain some understanding on treatment and precautions for different TBI cases. Other factors that affect symptoms after a TBI occurence include timing after the injury, age of the subjects, severity of injury, age of subjects, and region of the brain affected. These symptoms may also affect DTI results. [4] Below are what DTI imaging may look like and what information they present. 

Figure 2. Picture showing DTI scan results comparing a healthy brain to a brain after a head trauma.

Figure 3. Picture showing effects of mechanical impact on a brain cell following a TBI.

Another major symptom of TBI is neurocognitive impairment. More interestingly, many cognitive impairments resulting from TBI do not get diagnosed until brain scans of the patients brain after they have died. My closest experience to TBI was my involvement in an auto accident as a young child. My head was impacted, but I was told I was fine although no brain scans were done on my brain. 

After learning about this topic at such level, I definitely think I should get a long awaited brain scan, just to be safe! 

Figure 4. Artstract made by student showing some basic information and awareness on brain injury.

References:

Rauchman, S. H., Zubair, A., Jacob, B., Rauchman, D., Pinkhasov, A., Placantonakis, D. G., & Reiss, A. B. (2023, February 6). Traumatic brain injury: Mechanisms, manifestations, and visual sequelae. Frontiers. https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2023.1090672/full — first picture shwing symptoms of tbi

Weber , B., Fliessbach, K., & Elger , C. E. (n.d.). Diffusion tensor imaging. Diffusion Tensor Imaging – an overview | ScienceDirect Topics. https://www.sciencedirect.com/topics/medicine-and-dentistry/diffusion-tensor-imaging#:~:text=Diffusion%20tensor%20imaging%20(DTI)%20is,structural%20connections%20and%20interregional%20information

Paus , T. (n.d.). Fractional anisotropy. Fractional Anisotropy – an overview | ScienceDirect Topics. https://www.sciencedirect.com/topics/immunology-and-microbiology/fractional-anisotropy#:~:text=Fractional%20anisotropy%20(FA)%20indicates%20the,marker%20of%20axonal%20structural%20integrity.

Giza, C. C., & Hovda, D. A. (2014, October). The new neurometabolic cascade of concussion. Neurosurgery. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4479139/

Gordon, J. (2013, October 3). DTI – diffusion tensor imaging MRI for abnormal axonal tracts. Brain Injury Help. https://braininjuryhelp.com/dti-diffusion-tensor-imaging-mri/

How can diffusion tensor imaging MRI help in brain injury?. Brain Injury Law of Seattle. (2023, April 29). https://www.braininjurylawofseattle.com/how-can-diffusion-tensor-imaging-mri-help-objectively-document-a-brain-injury/

 

Glioblastoma; Cell Signaling, and Possible Treatment Targets

Picture 1: Glioblastoma pictured in the brain.

Glioblastoma (GBM) is an aggressive and invariable lethal form of cancerous brain tumor, and it’s among the types of cancer with the worst survival rates. This type of cancer is extremely invasive, and spreads rapidly to neighbouring structures as well as extending into healthy brain tissue[1]. There are two main types of GMB, which is primary and secondary. Primary GBM develop without evidence of any pre-existing symptoms or tumor, while secondary arises from a lower grade tumor. Additionally, there is various molecular subtypes of GBM, which are classical, mesenchymal, proneural and neural GBM[2].

The current standard treatment for GBM is surgery, radiotherapy, and a singular drug called temozolomide. The limited therapy is associated with GSM being relatively resistant to therapy, and due to the drug needing to cross the Blood Brain Barrier (BBB), additionally exhibiting robust radio-resistance[3].

Three cellular transduction pathways have been found to play a role for GBM, these are the MAPK, PI3K, and cAMP pathways:

Figure 1: The MAPK pathway, from the activation by ligands to its downstream effects[4].

The MAPK pathway was found to be frequently altered in GBM, and high levels of phosphorylated (or activated) MAPK being linked to poor survival among patients with GBM. Multiple components of this pathway is transformed in cancer leading to the hyperactivation[5].

Figure 2: The PI3K pathway, visualized from ligand binding to promoting various factors such as cell survival[6].

The PI3K regulator multiple cellular functions, and is frequently disturbed in cancer whereas components may be mutated or amplified. In GBM, mutations or amplicitations can be found of the EGFR, and activated in PIK3CA  which is the gene that encodes p110 within the PI3K pathway, and inactivating of PTEN (a tumor suppressor)[7].

Figure 3: The cAMP pathway, from ligand bind to downstream effects[8].

The cAMP pathway had been less prominent, but tend to be lower in tumor cells. However, it has been shown that the elevation of cAMP levels inhibit growth, increase differentiation as well as promote apoptosis in GBM cells[9].

With the limited amount of treatment currently offered for GBM, opens the discussion for ideas on new therapies or areas of target for treatment. Targeting the different signaling pathways shown to play a role in GBM can be beneficial for treating the tumors. A review from Cellular Signaling brought up a couple of possible treatments, in which are inhibitors and activators that have shown increased apoptosis in cancer cells lines. Some of the various ones that target the three signaling pathways, are a PI3K inhibitor called Buparlisib, a MAPK inhibitor, Vemurafenib, as for cAMP a AC activator called forskolin and a PDE inhibitor, isobutylmethylxanthine[10]. It has however been found that targeting individual pathways is not always that effective. This is because of pathway redundancy, and the ability tumors have to adjust their signaling to other pathways in order to maintain growth and their function. Therefore, targeting areas where the pathways coverage may be effective, which can be cAMP response element-binding protein (CREB). CREB is a transcription factor that crosstalk between these three signaling pathways. The transcription factor is important in a number of downstream functions, which include neurogenesis and cancer. CREB is important for normal brain development. It was found that in mouse brains the deletion of CREB lead to neurodegeneration during development[11].

So, how can CREB be used as treatment for GBM? There has evidence suggesting that CREB is important for regulating tumor initiation, its progression and metastasis, and based on this it has been demonstrated therapeutic potential in possible inhibitors of gene transcription mediated by CREB[12]. The current approaches are termed “CREB inhibitors” and “CREB-related pathways inhibitors”, which can be shown in Figure 4, separated by direct inhibitors in the nucleus, and pathway inhibitors outside of the nucleus[13].

Figure 4: An overview of the main intracellular pathways involved in CREB activation: the red arrows being possible pharmacological hubs for its inhibition[14].


Bibliography

[1] Fung, N.H., Grima, C. A., Widodo, S. S., Kaye, A. H., Whitehead, C. A., Stylli, S. S., & Mantamadiotis, T. (2019) Understanding and expliting cell signalling covergence nodes and pathway cross-talk in malignangt brain cancer. Cellular signalling, 57,2-9. https://doi.org/10.1016/j.cellsig.2019.01.011

[2]  Ibid.

[3]  Ibid.

[4]  Ibid.

[5]  Ibid.

[6] Ibid.

[7] Ibid.

[8] Ibid.

[9] Ibid.

[10] Ibid.

[11] Ibid.

[12] Xiao, X., Li, B. X., Mitton, B., Ikeda, A., & Sakamoto, K. M. (2010). Targeting CREB for cancer therapy: friend or foe. Current cancer drug targets10(4), 384–391. https://doi.org/10.2174/156800910791208535

[13] Sapio, L., Salzillo, A., Ragone, A., Illiano, M., Spina, A., & Naviglio, S. (2020). Targeting CREB in Cancer Therapy: A Key Candidate or One of Many? An Update. Cancers12(11), 3166. https://doi.org/10.3390/cancers12113166

[14] Ibid.

Reflection on My Time at Concordia

At Concordia, a liberal arts approach to learning is emphasized greatly and it is expected to help all students be exceptional contributors to the community, becoming responsibly engaged in the world. But what does this mean? Having the opportunity to learn in various different perspectives and looking at the world through different lenses is something I did not expect to appreciate coming into my college experience. As I would assume many first-year students feel, I thought these exploration courses were a waste of time and I just did not understand what the benefit was of taking these courses. Looking back at my time at Concordia, I cherish the fact that I was able to view the world through a religious perspective, a philosophical perspective, a scientific perspective, an arts perspective, and many more. It opens up your views and makes you see things from all angles which is the key to being a contributing member of society or any discipline that one may spend their life working in.

A key skill you learn through a diverse education that liberal arts provides is thinking critically and thinking of all possible perspectives. This allows you to recognize the best way to go about anything, what the best solution is to the problem at hand. One cannot possibly think of all possible approaches without being put in the position to think about problems in a completely different way that what might come naturally. Being a psychology major, thinking about behaviors and the way someone was brought up is where my mind goes naturally, but neuroscience and other natural sciences force me to think about what could be happening in the brain or the body that is causing certain personalities or actions. Without a liberal arts education, I would probably not be exposed to these ways of approaching ideas and problem solving, and I think having this experience makes me a more intelligent and well-rounded individual.

Critical thinking skills are definitely something that I improved on greatly during my time in Neurochemistry this semester. Going into discussions every week at the start of the semester was very difficult for me because the chemistry and really scientific ways of thinking are not where my mind goes immediately when talking about different disorders. My mind wants to go to the nurture side of the nature vs nurture debate, thinking about what is their early life is causing this disorder. Although this is still the way I approach these problems first, I have come to consider other reasonings or mechanisms for what is going wrong in each case.

Having this liberal arts education and being pushed cognitively to think critically is going to help me be a better collaborative partner going forward into the world which I think is one of the most appreciated qualities for someone to have not only in the workforce but it any relationships in life. Being able to see all perspectives and being flexible in how you think makes you work better in a group and have empathy for all people that you may interact with. I am incredibly grateful for this opportunity for me to grow and I am ready to become responsibly engaged in the world.

Could Diet Help Treat Concussions?

Concussions or traumatic brain injuries (TBI) occur when the head experiences an impact that causes structural damage to brain tissue. Depending on the severity of the injury, this damage may or may not be visible in images of the brain. Despite this, microstructural damage to neural tissue can have significant metabolic and neurochemical effects. This damage can induce chronic cell death and neurodegeneration. Alterations in cellular function can impair neurotransmission, induce metabolic changes, and trigger ionic shifts [1]. Even though these effects can be serious, there is not a universally accepted treatment protocol that modulates these altered pathways.

What Happens After TBI?

Immediately following a brain injury which results in damage to neural cell membranes, an ionic flux and hyperacute glutamate release can be observed. When the trauma alters the outer membrane of neurons, potassium ions rush out of the cell and sodium and calcium ions rush into the cell, due to the natural ionic gradient between the intracellular and extracellular regions. This initiates a depolarization within the cell, which induces a state of spreading depression which can be a major contributor to acute post-concussive symptoms such as headaches, migraines, and seizures [1].

Figure 1: Following structural damage to the brain (axonal damage), a variety of chemical and metabolic changes occur. These changes can induce the symptoms associated with TBI. [1]
Similarly, injury to axons of neural cells can promote extreme glutamate releases. Since glutamate is a major excitatory neurotransmitter, this can cause significant alterations to neurotransmission. Increased glutamate levels following TBI are associated with changes in the NMDA glutamate receptor which can affect memory, neuroplasticity, and electrophysiology of the brain. Glutamate release may also be related to increased cytokine and inflammatory gene responses following TBI which is associated with oxidative stress and cellular injury [1].

Figure 2: Glutamate becomes GABA when GAD is present. Following a concussion, decreased levels of GAD result in elevated glutamate and deficiencies in GABA. This glutamate/GABA imbalance can produce symptoms of anxiety from over-excitatory neurotransmission. 

Alterations in GABA, the major inhibitory neurotransmitter, and its receptors have also been observed in TBI models. This could be correlated to the increased susceptibility to anxiety and PTSD following a TBI. GABA transmission is known to produce anti-anxiolytic effects. For this reason, decreased levels of GABA and GAD67 (the enzyme that turns glutamate into GABA) in the amygdala following TBI may specifically contribute to the long-term increases in anxiety observed after brain injury [1].

Likely related to the ionic alterations following structural damage is the metabolic shift that is observed immediately and sustained for 7-10 days following TBI. Immediately following structural damage which induces ionic flux, the cells enter a period of hyperglycolysis in their attempt to return ionic gradients to resting levels. Following this initial increase in glucose metabolism that lasts less than 24 hours, the brain enters a period of impaired glucose metabolism. During this time, it is suggested increased fatty acid consumption could decrease some of the axonal damage that occurs after a concussion [1].

Ketones and Concussions

Fatty acid supplementation could be beneficial following TBI because ketones from the metabolism of fats can be used for fuel instead of glucose in the hypometabolic state. For this reason, it appears that direct ketone supplementation or a ketogenic diet may have more advantageous effects than fatty acid supplementation because ketone body levels are raised more effectively [6].

Figure 2

The ketogenic diet (KD) is a high fat, low carbohydrate diet originally used to treat epilepsy. This diet initiates a metabolic state of ketosis where ketone bodies are used for fuel instead of glucose. In a study investigating the potential benefits of a KD following TBI it was shown that compared to a standard diet, a KD produced more ketone bodies, reduced loss of neurons, reduced inflammation, and increased SIRT1 protein following SIRT1 loss due to injury. SIRT1 is a neuroprotective protein that is active in the hippocampus where it activates Akt and inhibits GSK [7].

 

Given the significant neurochemical and metabolic changes observed following TBI, as well as the vast and serious symptoms this can cause, it is concerning that there are not any highly effective medications or treatments to help heal the structural and metabolic damage that has occurred. The structural damage leads to ionic fluxes which alters brain metabolism, leading to a wide range of behavioral and physiological symptoms. In light of the current understanding of the neural ionic flux and its alterations to neurometabolism, ketone supplementation or a ketogenic diet may be a viable treatment option following a concussion.

References:

(1) Giza, C. C.; Hovda, D. A. The New Neurometabolic Cascade of Concussion. Neurosurgery 2014, 75 (Supplement 4), S24–S33. https://doi.org/10.1227/NEU.0000000000000505.
(2) Needle Induced Cortical Spreading Depression – Difference Image Mode; 2013. https://youtu.be/UkT65Y4iFrk?si=aW6zuOo85nbE4Et2.
(3) Colleen Doherty, MD. What Is Post-Concussion Syndrome?. VeryWellHealth. https://www.verywellhealth.com/post-concussion-syndrome-5185771#toc-post-concussion-syndrome-symptoms.
(6) Daines, S. A. The Therapeutic Potential and Limitations of Ketones in Traumatic Brain Injury. Front. Neurol. 2021, 12, 723148. https://doi.org/10.3389/fneur.2021.723148.
(7) Har-Even, M.; Rubovitch, V.; Ratliff, W. A.; Richmond-Hacham, B.; Citron, B. A.; Pick, C. G. Ketogenic Diet as a Potential Treatment for Traumatic Brain Injury in Mice. Sci Rep 2021, 11 (1), 23559. https://doi.org/10.1038/s41598-021-02849-0.

What’s Behind Brain Cancer

What is Glioblastoma?

Glioblastoma (GBM) is a type of cancer that forms in the brain or spinal cord. GBM forms from astrocytes that support nerve cells. [1]

Classical GBM

Characterized by amplification or mutation of the EGFR gene. This type typically responds better to aggressive treatment compared to other types. 

Mesenchymal GBM

Characterized by mutations of NF1 and PTEN, and mutations of P53 are also common. This type is also responsive to aggressive treatment. 

Proneural GBM

Characterized by amplification of chromosome 4q12 and high levels of the PDGFRA gene. IDH1 and TP53 mutations are also typically present in this type. People with this type tend to live longer compared to other types, but it does not respond well to aggressive treatment. 

Neural GBM

This type does not have any obvious patterns of mutations or amplifications and typically has the worst prognosis of all types. [2]

Figure 1. Scan of brain with glioblastoma [3]

Signal Transduction Pathways in Relation to GBM

MAPK 

High levels of MAPK signaling are connected to GBM. What could contribute to this is that in the mesenchymal type, NF1 is mutated which typically negatively regulates MAPK signaling by inactivating Ras. Another factor could be that in the classical type, the EGFR gene is amplified which hyperactives MAPK. 

PI3K 

The PI3K signaling pathway is hyperactive in GBM cases. What could cause this is the mutation of PTEN in the mesenchymal type which typically suppresses PI3K signaling by dephosphorylating PIP3. The EGFR gene amplification typical in the classical type also hyper-activates PI3K signaling. 

cAMP 

It has been found that cAMP signaling is hypoactive in GBM cases as there are low levels of cAMP and adenylyl cyclase in GBM tumor samples. CREB is a transcription factor that is activated through the cAMP signaling pathway, so if cAMP signaling is suppressed, CREB is inhibited which is connected to tumor growth.

Convergence of pathways

MAPK and PI3K cross regulate each other in many ways. For one, they are both activated by the same receptors and both activated by Ras proteins. ERK, a MAPK pathway, can downregulate PI3K by phosphorylating GAB1 which then reduces the activation of PI3K. ERK can also inhibit PI3K by activating mTOR. PI3K can also downregulate the MAPK signaling pathway by inhibiting Raf through the action of AKT and its phosphorylation of Raf. All three pathways involved, MAPK, PI3K, and cAMP seem to have some link to CREB and its inability to perform correctly which results in the modulation of tumor growth. [2]

Figure 2. Graphic of cAMP, MAPK, and PI3K signaling pathways and their interactions [2]

Current Treatments for Glioblastoma

Surgery

Surgery can remove some of the tumor but it often spreads to healthy tissue, so typically surgery is not fully effective. After surgery, patients tend to have other treatments done to get whatever is left. 

Radiation

Radiation therapy uses energy beams from X-rays or protons to kill cancer cells. Radiation is typically used in combination with chemotherapy. 

Chemotherapy

Chemotherapy uses drugs to kill cancer cells and can be taken as a pill or through a vein. 

Tumor treating fields (TTF) therapy

TTF uses an electrical field to keep cancer cells from multiplying. [1]

Figure 3. Model of TTF [4]

References

[1] Mayo Clinic. (March 7, 2024). Glioblastoma. https://www.mayoclinic.org/diseases-conditions/glioblastoma/cdc-20350148#:~:text=It%20can%20form%20in%20the,can%20happen%20at%20any%20age

[2] Fung, N. H., Grima, C. A., Widodo, S. S., Kaye, A. H., Whitehead, C. A., Stylli, S. S., & Mantamadiotis, T. (2019). Understanding and exploiting cell signalling convergence nodes and pathway cross-talk in malignant brain cancer. Cellular Signaling, 57, 2-9. https://doi.org/10.1016/j.cellsig.2019.01.011

[3] Kwatra, G. (2021, August 30). Glioblastoma: What Every Patient Needs to Know. Glioblastoma Foundation. https://glioblastomafoundation.org/news/glioblastoma-multiforme

[4] Li, X., Oziel, M., & Rubinsky, B. (2022). Evaluating the therapeutic effect of tumor treating fields (TTFields) by monitoring the impedance across TTFields electrode arrays. PeerJ, 10. https://doi.org/10.7717/peerj.12877 

Subcategorizing ASD: The Role of Dopamine

Autism Characteristics

Autism Spectrum Disorder (ASD) is a common neurodevelopmental disorder that is diagnosed based on behavioral symptoms. Given the wide-ranging manifestations of the symptoms of ASD, it would be helpful to be able to find more precise diagnostic criteria to provide more specific diagnoses which could allow for more precise treatments. The symptoms of ASD are broadly described as deficits in social communication and interaction as well as restrictive, repetitive behaviors [1]. Since these symptoms are very broad, it is no wonder that there is not thought to be a single cause of ASD. Alternatively, many assorted mechanisms and genetic variations are thought to be associated with behavioral expressions that can be characterized as ASD [2].

The high heritability of ASD is strong evidence for the genetic influence on the variety of manifestations of the condition. This is also supported by the discovery of many de novo single nucleotide variants as well as transmitted and de novo copy number variants. Because of the wide range of possible contributions and outcomes related to ASD, it is suggested that ASD diagnoses should be subcategorized based on mechanistic commonalities found within different expressions of ASD. One mechanism that could be used to subcategorize ASD is that of dopamine signaling dysfunction [2].

Dopamine Dysfunction in ASD

Image 1: The caudate nucleus is a major dopamine hub within the brain. In patients with ASD, this region becomes significantly enlarged, which is shown highlighted in red and blue. [5]
A strong piece of evidence for this theory is found in MRI studies of the caudate nucleus. The caudate nucleus is a major target of dopamine signaling. Multiple studies have found enlargement of the caudate nucleus (Image 1) in individuals with ASD. This suggests that ASD is associated with alterations in dopamine related structures and the function of these structures. Similarly, increases in connectivity of the fronto-striatal networks has been positively associated with the severity of repetitive behaviors in ASD. This also links ASD symptoms with abnormal dopaminergic connectivity to cortical structures [2].

Figure 1: Representation of the dopamine (DA) signaling pathway and ASD associated variants. Red numbers indicate downregulation, reduction, or inhibition. Green numbers indicate upregulation or potentiation [2].
There have been many ASD-associated variants within the dopamine signaling pathway reported from various models (Figure 1). Although the direct application of these variants and the degrees of their effects cannot be completely deduced at this time, the significance in this information is that there appears to be many sites of action within the dopamine pathway that are altered in ASD models. Both upregulation and downregulation at specific points within the pathway emphasize the role of dopamine dysfunction in the behavioral manifestations of ASD [2].

Figure 2: Dopaminergic projection patterns within the brain. Synthesis primarily occurs in the substantia nigra (SN), the ventral tegmental area (VTA), and the hypothalamus. The arrows represent the projections from the sites of synthesis. [2]
Given the vast projection patterns of dopamine in the brain (Figure 2), the many variants in dopamine signaling with ASD (Figure 1), as well as the studies linking ASD with changes in dopamine signals and structures, it is difficult to deny the evidence supporting a connection between dysfunction of the dopamine system and ASD behaviors. Dopamine has extensive effects on human behavior including social drive, reward-associated behaviors, allocation of physical energy, attention, and working memory, just to name a few. This broad scope of dopamine related activity could have many implications on the broad scope of ASD manifestations [2].

Resources:

(1) Diagnostic Criteria for 299.00 Autism Spectrum Disorder. CDC. https://www.cdc.gov/ncbddd/autism/hcp-dsm.html.
(2) DiCarlo, G. E.; Wallace, M. T. Modeling Dopamine Dysfunction in Autism Spectrum Disorder: From Invertebrates to Vertebrates. Neuroscience & Biobehavioral Reviews 2022, 133, 104494. https://doi.org/10.1016/j.neubiorev.2021.12.017.
(3) Chris Gunter, Ph.D. Single Nucleotide Polymorphisms (SNPS). National Human Genome Research Institute. https://www.genome.gov/genetics-glossary/Single-Nucleotide-Polymorphisms.
(4) Daniel A. Gilchrist, Ph.D. Copy Number Variation (CNV). National Human Genome Research Institute. https://www.genome.gov/genetics-glossary/Copy-Number-Variation.
(5) Qiu, T.; Chang, C.; Li, Y.; Qian, L.; Xiao, C. Y.; Xiao, T.; Xiao, X.; Xiao, Y. H.; Chu, K. K.; Lewis, M. H.; Ke, X. Two Years Changes in the Development of Caudate Nucleus Are Involved in Restricted Repetitive Behaviors in 2–5-Year-Old Children with Autism Spectrum Disorder. Developmental Cognitive Neuroscience 2016, 19, 137–143. https://doi.org/10.1016/j.dcn.2016.02.010.

A Kernel of Knowledge

When I chose to come to Concordia for college, I didn’t know the impact it would have on my life.  I don’t want to be a clique… but what everyone says is true, “these 4 years have really flown by.” When thinking about life after college, I have been thinking a lot recently about how my experiences at Concordia have helped prepare me for the future.

Concordia has a goal for its liberal arts education called BREW – Becoming Responsibly Engaged in the World. My liberal arts education has prepared me to not only be a curious thinker and the importance of mentor and classmate relationships, but Concordia specifically emphasizes experimental learning that allows students to connect the concepts they are learning outside the classroom as well. This has helped me to build critical thinking skills and to realize the importance of community outreach and gaining multiple perspectives.

When I read about Concordia’s 5 goals for liberal learning, I thought of research. Research is committing to learn for the rest of your life. It’s a love for learning and a drive to follow whatever research questions interest you. Research is continuing to build on your foundation of knowledge and research techniques (i.e. research process, scientific writing, safe laboratory practices, etc.). Research is being able to communicate your findings so that anyone can understand. Wanting to go into a future career in research, I’ll be taking what I have learned at Concordia and applying it to all aspects of my life.

This neurochemistry course has been one of my favorites at Concordia because of its unique structure (it also helps that this is basically the theory behind what I want to do for the rest of my life). During this class, I have learned how to take real-world issues, read current literature, and discuss the complex problems in their mechanisms, treatment, and public perceptions with my classmates. Each week when we read about a new disease, my favorite part is getting to the point where I have learned enough to consider and pose future directions for research on the disrupted signaling pathways and treatments that target them.

If I were to highlight skills or competencies that I improved upon this semester in my resume or an interview, I would be sure to include reading and comprehending complex diseases from recent literature, collaborating with peers, writing blog posts to present findings to the public, and applying critical thinking to understand complex issues involved in diseases. In my future career, I will take what I have learned from this neurochemistry course and use it to understand complex neurological disorders and work to communicate scientific topics effectively with diverse audiences.

I’ve experienced how the lives of children who have ASD as well as their families can be impacted. To research autism from translational approaches in my future career, I am going to need to learn and draw from multiple disciplinary perspectives: Genetics to study the common mutations found and their possible implications in the different pathologies (E/I imbalances, abnormal synapse formations, etc.);  Biochemistry to understand the underlying signaling pathways that are disrupted; Psychology to understand the impact on behavior; and Neuroscience to bridge all these disciplines in a translational approach to understanding, diagnosing, and treating ASD.

I know my experiences at Concordia have prepared me for my future, the kernel was planted, and I can’t wait to see how it grows!

A New Hope for Treatment of Brain Tumors

Glioblastomas

Glioblastomas (GBM) are the most common and deadly malignant brain cancer. These brain tumors are aggressive, with their complex genetic makeups and relentless growth patterns. Because of its complexity GBMs are hard to treat, current treatments rely on surgery, chemotherapy, and a single drug – TMZ. GBMs can manifest as primary tumors, emerging rapidly without warning, or as secondary tumors evolving from lower-grade gliomas over several years.

There are four subtypes of GBMs, each with its own molecular fingerprints. The classical subtype is characterized by amplified epidermal growth factor receptor gene (EGFR) and non-mutated TP53 proteins. In contrast, the mesenchymal subtype has common mutations in neurofibromin 1, PTEN, and TP53. These genes are involved in MAPK and PI3K signaling pathways and contribute to tumor cells’ invasiveness and drug resistance. Other subtypes show the heterogeneity challenges of GBM, with pro-neural subtypes classifying younger patients who have multiple genetic mutations and neural subtypes with the worst survival rate and no common genetic pattern.

 

Figure 1. Gene mutations can lead to the formation and invasiveness of tumor cells (3).

A recent paper looking into the underlying mechanisms of GBMs highlighted the potential to target convergence points and crosstalk of signaling pathways involved in cancer pathogenesis.

Signaling Pathways that Promote GBM Carcinogenesis

Hyperactivation of the pathways seen below in Figure 2, often stemming from gene mutations that cause EGFR amplifications or PTEN inactivation, increases tumor growth and GBM progression.

Figure 2. Multiple signaling pathways including MAPK, PI3K, and cAMP contribute to cancer pathogenesis (1).

MAPK Pathway

This pathway regulates cell proliferation (cell survival) and metastasis (how cancer spreads). In cancer, the MAPK pathway is hyperactive because of the mutation-driven higher levels of EGFR growth factors. EGFR activates the MAPK pathway that promotes proto-oncogene transcription factors like Elk1 and CREB to allow tumor cells to multiply. The gene NF1 negatively regulates the MAPK pathway by converting GTP to GDP, inhibiting Ras. This genetic component is seen in 14% of mesenchymal GBM cases, as NF1 is depleted or mutationally inactivated, leading to hyperactive MAPK pathways.

PI3K Pathway

This pathway regulates cell growth and when dysregulated promotes tumor cell invasion. In GBM, PI3K pathways are hyperactive because of genetic mutations that lead to increased levels of EGFR, PIK3CA (the gene that encodes the p110 catalytic subunit of PI3K), and inactivated PTEN genes. Growth factors and Ras activate the PI3K pathway activates the mTOR pathway and transcription factors that promote cell growth. The PTEN gene negatively regulates the PI3K pathway by converting PIP3 to PIP2, leading to the inhibition of Akt, an important role in moderating normal cell growth levels. Disrupted PI3K pathways increase MMP levels, which lead to degraded extracellular matrices and contribute to GBM tumor cell invasiveness.

Tumor Cells and Drug Resistance

GBMs are very resistant to drug treatment because of the multiple signaling pathways that promote tumor growth—MAPK and PI3K pathways. Drug resistance is common in GBMs because targeting one pathway leads to the tumor cells using another pathway to continue its proliferation. This ability to resist is why current drugs that target convergence points of the multiple pathways involved are being researched (the asterisks in Figure 2 above are the possible convergence points).

Potential Drug Targets Focused on Convergence Points Between Pathways

The intricate crosstalk between MAPK and PI3K pathways further complicates therapeutic interventions. While both pathways can be activated by common receptors and Ras proteins, they also exhibit cross-inhibition and cross-activation mechanisms involving their main molecules (GAB1, ERK, TSC1/2, mTORC1, and Akt). Targeted inhibitors against PI3K, MAPK, EGFR, and CREB signaling have shown promise in preclinical studies, yet the challenge of adaptive pathway resistance to single drug targets has highlighted the potential of a combination of drug targets as a future treatment strategy.

Figure 3. Tumor microenvironments are important to consider when considering what to target in drug treatments (4).

Nothing in Glioblastomas makes sense, except in the light of mutationally amplified EGFR genes causing hyperactivation of both the MAPK and PI3K pathways, leading to GBM carcinogenesis.

 

References

[1]  N. H. Fung et al., “Understanding and exploiting cell signalling convergence nodes and pathway cross-talk in malignant brain cancer,” Cellular Signalling, vol. 57, pp. 2–9, May 2019, doi: 10.1016/j.cellsig.2019.01.011.
[2]  J. E. Strait, “Brain cancer vaccine effective in some patients,” Washington University School of Medicine in St. Louis. Accessed: Apr. 29, 2024. [Online]. Available: https://medicine.wustl.edu/news/brain-cancer-vaccine-effective-in-some-patients/
[3]  “Treating Mutations in Cancer Research | LIDE Biotech.” Accessed: Apr. 29, 2024. [Online]. Available: https://www.lidebiotech.com/blog/cancer-mutations
[4]  J. Hou et al., “Evolution of Molecular Targeted Cancer Therapy: Mechanisms of Drug Resistance and Novel Opportunities Identified by CRISPR-Cas9 Screening,” Front. Oncol., vol. 12, Mar. 2022, doi: 10.3389/fonc.2022.755053.

What to Know About the Endocannabinoid System

CB1 Receptors

CB1 receptors are G-protein coupled receptors (GPCRs) that are mostly found in the central nervous system (CNS) but can also be found in peripheral tissues and the peripheral nervous system (PNS). They are found on presynaptic neurons. These receptors play an essential role in learning and memory and synaptic plasticity. When these receptors are coupled with Gi/o proteins, they inhibit adenylyl cyclase, and when they are coupled with Gs proteins, they stimulate adenylyl cyclase. [1]

CB2 Receptors

CB2 receptors can be found in cells and tissues of the immune system and are typically only expressed when there is active inflammation in the body. They are typically localized to microglia which have anti-inflammatory effects. [2]

Figure 1. Graphic differentiating CB1 and CB2 receptors of the endocannabinoid system [3]

Endocannabinoid System 

Endocannabinoids are natural agonists for the CB1 and CB2 receptors. They are triggered by the release of calcium at the postsynaptic neuron. The endocannabinoid system controls mood, pain perception, and learning and memory. It can also provide protection against traumatic brain injury (TBI) and can repair neurodegeneration. Learning and memory comes into play with the endocannabinoid system as it plays a key role in modulating synaptic plasticity—the ability of the brain to change connections between neurons. [4]

Figure 2. Cannabis and the brain [5]

THC vs CBD

CBD and THC are both derived from cannabis plants and have very similar molecular structures. The primary difference between the two is that THC is psychoactive and CBD is non-psychoactive. CBD products are federally legal whereas THC is not and is only legal in some states. CBD is also not considered addictive whereas THC can lead to addiction (about 30% of marijuana users become addicted). [6]

Figure 3. Image showing the different molecular structure of THC vs CBD [6]

Cannabis as Treatment for Neurodegenerative Diseases 

Multiple Sclerosis

Cannabis, particularly THC, can have positive effects on spasticity and pain in multiple sclerosis (MS). Sativex, a spray that is ingested through the mouth or nose and is composed of both CBD and THC, has been used to treat MS. This treatment acts on both CB1 and CB2 receptors to reduce both pain and inflammation. 

Huntington’s Disease

In Huntington’s disease, CB1 receptor expression is reduced which decreases motor performance. To treat Huntington’s disease, CB1 can be activated to reduce symptoms. 

Alzheimer’s Disease

Alzheimer’s disease (AD) is partially characterized by dementia and synthetic endocannabinoids may better dementia symptoms in AD. AD is believed to be caused by amyloid-beta plaques and tau protein phosphorylation. Activation of both CB1 and CB2 receptors can provide protection against amyloid-beta toxicity, and CBD can reduce tau protein phosphorylation. [4]

Figure 4. Image of different forms of cannabis used for treatment [7]

Ethical Concerns in Research 

Since cannabis is not federally legal and only legal in some states, research participants could be at legal risk if their identity is disclosed. Another issue is impairment of participants and making sure that researchers are getting informed consent. Ensuring that consent is received prior to any ingestion of the drug is imperative for ethics of the study. Individuals’ ability to understand and make sound decisions could be impaired under the influence of cannabis. [8]

Figure 5. Image of cannabis being used for research [9]

References

[1] Howlett, A. C., Blume, L. C., & Dalton, G. D. (2010). CB(1) cannabinoid receptors and their associated proteins. Current medicinal chemistry, 17(14), 1382–1393. https://doi.org/10.2174/092986710790980023 

[2] Bie, B., Wu, J., Foss, J. F., & Naguib, M. (2018). An overview of the cannabinoid type 2 receptor system and its therapeutic potential. Current opinion in anaesthesiology, 31(4), 407–414. https://doi.org/10.1097/ACO.0000000000000616 

[3] What is the Endocannabinoid System? | Sona Pharmacy + Clinic. (2020, April 1). https://sonapharmacy.com/what-is-the-endocannabinoid-system/

[4] Kendall, D. A. & Yudowski, G. A. (2017). Cannabinoid Receptors in the Central Nervous System: Their Signaling and Roles in Disease. Frontiers in Cellular Neuroscience, 10(294). doi: 10.3389/fncel.2016.00294 

[5] ​​Goldberg, Ian. (March 2, 2023). Cannabis use and its effects on mood disorders | Talkiatry. Retrieved April 29, 2024, from https://www.talkiatry.com/blog/cannabis-use-and-its-effects-on-mood-disorders

[6] Center, L. H. T. (2023, November 15). CBD vs THC: Learn the Differences. La Hacienda. https://www.lahacienda.com/blog/cbd-vs-thc-learn-the-differences 

[7] ​​CDC. (2023, March 1). What We Know about Marijuana. Centers for Disease Control and Prevention. https://www.cdc.gov/marijuana/featured-topics/what-we-know-about-marijuana.html

[8] Fitzgerald, Kelly. (n.d.) Research and Cannabis: Ethical Research in a Changing Regulatory Landscape. Retrieved April 29, 2024, from https://www.wcgclinical.com/insights/research-and-cannabis-ethical-research-in-a-changing-regulatory-landscape/ 

[9] Corder, Katie-Leigh. (August 23, 2018). How UNC Researchers are Studying Cannabis. https://www.unco.edu/news/articles/unc-cannabis-research-projects.aspx 

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