Cancer research and cannabinoids

Cannabinoids: mechanisms in gliomas and its possible role in treatment

Virginia Thornley, M.D., Neurologist, Epileptologist
@VThornleyMD

July 18, 2018

Introduction
Glioblastoma multiforme is one of the most malignant types of cancer with a survival rate of less than 5% after 5 years. This may be due to a number of reasons including aggressive angiogenesis, active proliferation of cells and necrosis. In addition, it was found that there are a stem-cell like cells involved which may account for some of its resistance to treatment consisting largely of surgical resection and radiation treatments.

This looks into the role cannabinoids may play in the treatment of gliomas under which glioblastoma multiforme is categorized. Every mechanism is key in providing valuable information in targeting various mechanisms to assist with treatment.

Cannabinoid system and evidence of a role in gliomas

Phytocannabinoids have been identified from the plant cannabis sativa including delta-9-tetraydrocannabinol and cannabidiol. There are 2 significant receptors CB1 receptor and CB2 receptors. Within the endocannabinoid system there are 2 well-studied endocannabinoids, 2-arachidonoylglycerol (2-AG) and anandamide (AEA) and G-related proteins (1). delta-9-tetrahydrocannabinol is a pharmacomimetic of anandamide while cannabidiol is a mimetic of 2-AG. Anandamide is metabolized by fatty acid amide hydrolase or FAAH while 2-AG is metabolized through monoacylglycerol lipase (MAGL).

The receptors are of 2 types. The CB1 receptor is found predominantly in the nervous system in areas subserving pain modulation, memory, and movement. The CB2 receptor is peripherally found in the immune system. The CB2 receptor is found to a lesser extent in other organ systems including adrenal, cardiac, endocrine, pulmonary, gastrointestinal and gynecological organs.  Cannabinoids react with the TRPV receptor or the transient receptor cation channel subfamily V. They can act on G receptors including GPR55 which is thought to influence inhibition of seizures. Other receptors include GPR12, GPR18, and GPR119 (2).

Evidence of a role in gliomas

In glioblastoma multiforme, degrading enzymes of anandamide were found to be reduced with 60% reduction of fatty acid amide hydrolase (FAAH). Anandamide was found to be significantly increased compared to non-tumor tissue. In meningiomas, 2-AG were found to be significantly increased. This points towards elevation of levels of endogenous cannabinoids in the presence of tumor cells which may possibly signal an anti-tumor process by modulating cannabinoid receptor mechanisms (3).

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In pediatric low grade gliomas, it was found that in one cohort there was a spontaneous
involution of the tumors after a subtotal resection. Patients were followed 10 years. Analysis of gene expression and microRNA expression was studied. There was a different set of genes and microRNA expressions discovered in tumors that involuted spontaneously and those that were stable and showed no progression. The CB1 receptor was found to be expressed more abundantly using immunohistochemistry (4). This study suggests that CB1 receptor numbers may corroborate with a better prognosis and suggests a role of endocannabinoids in a more positive prognosis in pediatric low grade glioma.
How cannabinoids play a role in treatment against gliomas

There are various mechanisms by which cannabinoid can modulate the pathogenesis in tumors including proliferation, invasion, cell survival. Cannabinoids are thought to be involved mechanistically in the anti-proliferative, anti-migration and apoptotic effects of tumor cells in gliomas.

Cannabinoids may make tumor cells in gliomas more susceptible to radiation

One study found that cannabinoids may make tumor cells in gliomas more strongly susceptible to irradiation. When heat shock proteins were treated with CBD, they were upregulated. This did not occur in the setting of THC. Heat shock proteins are important in degradation, assembly,  and transcription  factor regulation. They are important in cell survival in the setting of abnormal pH, temperature and inflammation which may be caused by abnormal stability in the cell related to hypoxia, oxidative stress and temperature. Heat shock proteins are associated with resistance of tumor cells to treatment and a poorer prognosis (5). Heat shock proteins can inadvertently promote cancer cell survival, hence, their presence may correlate with a poorer prognosis. Cannabinoids were found to increase reactive oxidative stress leading to an alteration in the expression of HSP’s by increasing it. Increased HSP’s may alter the cytotoxicity of CBD towards cancer cells. By using an HSP inhibitor in conjunction with CBD, there may be better impact of irradiation of tumor cells. In summary, CBD along with HSP inhibitors may make tumor cells in gliomas more vulnerable to tumor irradiation (6).

Cannabinoids causes tumor cell death through apoptotic mechanisms

In one study, cannabinoids were found to have an anti-proliferative effect on tumors. Apoptosis is reduced by mechanisms where cannabinoids stimulate the pro-apoptotic ceramide which subsequently has impact on cell proliferation, differentiation and apoptosis in tumors (7).

In another study, there is supportive evidence that sphingolipid metabolism changes. This causes tetrahydrocannabinol to change the sphingolipid content in the endoplasmic reticulum, autolysosomes and autophagosomes. This contributes towards cell death promotion by autolysosomes which are stimulated by the cannabinoids (8).

Another study confirms that arachidonoylethanolamide (AEA) or anandamide which is the most potent endogenous cannabinoid works through anomalously expressed vanilloid receptor-1 (VR-1) in activating apoptosis in glioma cell lines through this receptor (9). THC is a mimetic of anandamide and may induce apoptosis through this mechanism. This may represent a potential specific molecular mechanism where therapeutic agents may be developed.

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Cannabinoids reduce angiogenesis and proliferation of glioma cell lines

In the human cell glioma cell lines U-87MG and T98G, cannabidiol was found to inhibit the proliferation and cell invasion of these cancer cell lines. These results are significant since aggressive tumors have an ability for normal tissue invasion and proliferation leading to a poor outcome. The doses required for reduction of invasion was less compared to the dosage needed to prevent proliferation. Cannabidiol demonstrated the ability to inhibit different proteins necessary for cell invasion of the 2 cell lines including MMP-9, TIMP-1, TIMP-4, uPA, VEGF and SerpinE1-PAI. Their roles play a significant part in metastasis and vascular proliferation (10). Interestingly, T98G cell lines were found to be delta-9-THC resistant.

Cannabinoids reduce MMP9 which is important in tumor cell invasiveness

MMP are proteases and are increased in the presence of gliomas signaling the invasiveness of the tumor. Cannabinoid inhibition of MMP9 may be the way by which invasiveness of the tumor is reduced. Inhibition of TIMP was also noted in the presence of cannabinoids, which is demonstrated in clinically aggressive gliomas (10).

Cannabinoids inhibits HIF-1 which allows tumor cells to thrive in hypoxic settings

Another significant concept produced by the research is cannabidiol inhibition of HIF1-alpha (or hypoxia induced factor) which is a transcription factor serving a regulatory role in the setting of hypoxia. Hypoxia occurs in fast-growing tumors when the demands for oxygen are outpaced and hypoxia results. In the setting of hypoxia, HIF1-alpha allows tumor cells to thrive in hypoxic conditions through migration, survival and vascular proliferation allowing these tumors to be resistant to chemotherapy (10).

Cannabinoids can modulate mechanistic properties of tumor cells in gliomas

One study demonstrated that cell “stiffness” correlates with the aggressiveness of invasion from tumor cell lines and may represent a mechanistic cell marker to signal invasiveness of a tumor. Cannabinoids can modulate the mechanistic properties of tumors and may be a potential anti-tumor therapeutic target in glioma cell lines(11).

Summary

In summary, cannabinoids are demonstrated to have a role in significant mechanisms involved in tumor activities including anti-proliferation, anti-migration, anti-angiogenesis and anti-survival. Cannabidiol inhibit conditions where transcription factors cause cancer cells to thrive in hypoxic environments which is crucial in the aggressive profile of malignant tumors. Cannabidiol reduces MMP9 significant in invasiveness. Cannabidiol along with HIF inhibitors can make gliomas more radiation susceptible.

The pre-clinical studies are accumulating rapidly which each discovery. Every mechanism elucidated counts towards potential therapeutic targets in gliomas. Pre-clinical studies do not always translate to human studies but the science is gaining headway.

Introduction/Disclaimer

About

References
  1. Wang, et al. Quantitative Determination of delta 9-tetrahydrocannabinol, CBG, CBD, their acid precursors and five other neutral cannabinoids by UHPLC-UV-MS. Planta. Med, 2019, Mar., 84 (4):260-266
  2. Landa, et al, “Medical cannabis in the treatment of cancer pain and spastic conditions and options of drug delivery in clinical practice,”Biomed. Pap. Med. Fac. Univ. Palacky Olomouc Czech Repub., 2018, Mar; 162(1):18-25
  3. Petersen, G., Moesgaard, B., Schmid, P.C., Broholm, H., Kosteljanetz, M., Hansen, H.S. Endocannaboinoid metabolism in human glioblastomas and meningiomas compared to human non-tumour brain tissue. J. Neurochem. 2005, Apr., 93 (2):299-309
  4. Sredni, S.T., Huang, C.C., Suzuki, M., Chou, P., Tomita, T. Spontaneous involution of pediatric low-grade gliomas: high expression of cannabinoid receptor 1 (CNR1) at the time of diagnosis may indicate involvement of the endocannabinoid system. Childs Nerv. Sys.t 2016, Nov, 32(11):2061-2067
  5. Calderwood, S.K., Khaleque, A., Sawyer, D.B., Ciocca, D.R., Heat shock proteins in cancer: chaperones to tumorigenesis. Trends in Biochemical Sciences. 2006, Mar. 31(3):164-172 
  6. Scott, K.A., Dennis, J.L., Dalgeish, A.G., Liu, W.M. Inhibiting heat shock proteins can potentiate the cyototoxic effect of cannabidiol in human glioma cells. Anticancer Research. 2015, Nov., 35 (11):5827-583 
  7. Ellert-Miklaszewska, A., Ciechomska, I., Kaminska, B. Cannabinoid signaling in glioma cells. Adv. Exp. Med. Biol. 2013, 986:209-220
  8. Hernandez-Tiedra, s., Fabrias, G., Davila, D., Salanueva, I.J., Casas, J., Montes, L.R., Anton, Z., Garcia-Taboada, E., Salazar-Roa, M., Lorente, M., Nylandsted, J., Armstrong, J., Lopez-Valero, I., McKee, C.S., Serrano-Puebla, A., Garcia-Lopez, R., Gonzale-Martinez, J., Abad, J.L.,, Hanada, K., Boya, P., Goni, F., Guzman, M., Lovat, P., Jaatela, M., Alonso, A., Velasco, G. Dihydroceramide accumulation mediates cytotoxic autophagy of cancer cells via autolysosome destabilization. Autophagy, 2016, Nov. 12 (11):2213-2229
  9. Contassot, E., Wilmotte, R., Tenan, M., Belkouch, M.C., Schuriger, V., de Tribolet, N., Burkhardt, K., Dietrich, P.Y. Arachidonoylethanolamide induces apoptosis of human glioma cells through vanilloid receptor-1. J. Neuropathol. Exp. Neurol. 2004 Sep, 63(9):956-63
  10. Solinas, M., Massi, P., Cinquina, V., Valenti, M., Bolognini, D., Gariboldi, M., Monti, E., Rubino, T., Parolaro, D. Cannabidiol, a non-psychoactive cannabinoid compound, inhibits proliferation and invasion in U87-MG and T98G glioma cells through multitarget effect. PLoS One 2013, 8(10):e76918
  11. Hohmann, T., Grabiec, U., Ghadban, C., Feese, K., Dehghani, F. The influence of biomechanical properties and cannabinoids on tumor invasion. Cell Adh Migr 2017, 11(1):54-67

 

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Epilepsy, Glaucoma, pain, Peripheral neuropathy, Tumor

Medical Marijuana: why the huge disconnect between physicians, laws, policies, and patients?

Virginia Thornley, M.D., Neurologist, Epileptologist

March 11, 2018

Introduction

A patient comes to you asking “Doc, my seizures are getting worse, I really hate the side effects of my medications, I really want to go a different route. Have you heard about medical marijuana?” You start sweating profusely, fidgeting in your seat, thinking of every single reason why not to recommend it and come up with  the standard response, “uh, well, I’m not qualified to recommend it and it’s not FDA approved, plus we don’t really know much about it there could be so many side effects.” And then we have the oldie but goodie response, “there’s not enough large randomized control trials to recommend it.” This scene plays 100,000 times over if not a million times over in physician offices across the country. Patients who are disillusioned with adverse effects of medications are looking towards alternative therapy. As surprising as it sounds, patients with chronic pain do not want to get intoxicated by opioids. In fact, some want to be tapered off of them or refuse them all together. Patients with end-stage cancer at the terminal stage of their lives wish to live a comfortable and humane existence without the need for more chemotherapeutic medications or pain medications that consistently make them feel like a zombie. While other patients with epilepsy may be on 4 different anti-epileptic agents and can no longer function or have a good quality of life because of side effects. There are two sides to every coin.

Why you should be educated on cannabidiol and THC use in medical conditions

If patients do not get their answers from their trusted physicians who they trust with their well-being, their health, the temples of their souls, they will go to great lengths in procuring this knowledge. This is via various sites on the internet some of the dubious nature others are from high quality companies that have been in business even before this seeming treatment fad started. Or, the information may be obtained from their brother-in-law’s friend’s hair stylist who is now pain-free after going through a long course of pain medications including ablative treatments, physical therapy, and acupuncture and has a physician who does recommend it. Like it or not, cannabidiol and tetrahydrocannabinol are alternative treatment options and are gaining more and more traction. To ignore it is to be complacent with the changing direction and landscape of medicine. As patients become more and more disillusioned by the limitation of conventional treatments, attention is directed towards alternative regimens. It is not just for the yoga-practicing patient looking for more natural methods, one sees the sweet 83-year-old gentleman who must be someone’s grandfather with the chronic hip pain of 50 years who have failed opioids and is simply looking for pain relief.

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Is there any evidence that it works?

The endocannabinoid pathway is found naturally in the system. It is responsible for the runner’s sense of wellbeing one gets after a 5-mile run and the pleasant mood you get after a 1-hour work-out with Zumba. There are 2 receptors in the system CB1 receptor which has the highest number of brain cells and the CB2 receptor which is found predominantly in the immune system. There are 2 common cannabinoids cannabidiol and tetrahydrocannabinol which exert various medical effects. Cannabidiol (CBD) has a weak affinity for the CB1 receptor and one needs 100 times the amount to get the same euphoria that one gets from tetrahydrocannabinol, the bane of every ER physician. Unfortunately, the side effects of euphoria of THC have preceded its popularity as a medical product. Little do we know it was once used for hundreds of years as a medication before the psychoactive properties were exploited for recreational purposes. In urologic culture cell lines, it is found that cannabinoids may reduce proliferation of cancer cells and reduce the pro-inflammatory microenvironment that is necessary for metastatic conditions (1). Human studies are still needed to determine a reduction in tumor loads. THC receptors are found in retinal cells and may be found to reduce intraocular pressure in glaucoma (5, 6). Cannabidiol is found to bind to the 5HT1 receptor which reduces anxiety. THC has been well-established in the mouse model to promote the inhibitory control of excitatory pathways in the hippocampus, where seizures commonly arise (8). There is an increase in CB1 receptors after prolonged seizures suggesting a compensatory response.  It has been used in combination and found in several randomized control trials to reduce the frequency of seizures by as much as 36% in medically refractory patients (2). It is well-established that cannabinoids reduce pain refractory to conventional medications (3). It has been found in bench research to be an antioxidant and have anti-inflammatory properties (4, 7). Some studies cite side effects of somnolence, nausea, dysphoria, however, it is not clear what was the quality of cannabinoids or dosages were used. At high doses, while THC can reduce pain it may also result in side effects, which is why it is usually used in combination with CBD which ameliorates the side effects of THC.  In addition, cannabidiol by itself has no euphoria and it takes 100 times the amount to achieve intoxication seen with THC use. Synthetic products will have more side effects than products that are organic meaning only of natural materials.

Given the huge amount of evidence in several different medical conditions (3), the results should overwhelmingly be towards a push in using cannabinoids more frequently. However, because of the cynicism of the public, physicians even of patients, who have been exposed more frequently to the harmful psychoactive side effects, the benefits are far overshadowed. More clinical randomized controlled trials are needed. Most literature cites small numbers of patients enrolled in studies or review multiple medical centers where the conditions are not uniform. In addition, some of the patients that would benefit the most are the least in numbers such as those with rare neurological conditions such as Dravet syndrome or Lennox-Gastuat syndrome.

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In conclusion

As it still stands, many states still do not recognize the medicinal value of cannabidiol or tetrahydrocannabinol. In some states, medical physicians are not allowed to recommend it and put themselves at risk for FBI questioning in even suggesting its use. It is not uncommon for patients to move states or order from other states or countries to procure this liquid gold that is supposed to work wonders. Only time will tell if this is a passing fad and if there are long-standing side effects, however, as of current standing, medical marijuana is here to stay. As far as the literature goes, there are beneficial results but it is a cautionary tale as more studies in large human trials are still needed. As with any new preclinical data, the preclinical status may get ahead of itself and human trials do not replicate the desired results. But from the small clinical trials in seizures, pain, nausea, anxiety, and loss of appetite, the results are promising while more research is needed for anti-tumor effects in humans.

As with any medication, there will be clear-cut side effects just as with any other medication which is why more studies are needed to determine the least amount with the least amount of side effects. In some studies,  amounts upwards of 50mg/kg (2) is used the high amounts likely responsible for causing side effects, which is far higher than that cautioned by medical marijuana dispensaries. It will take patients time to wrap their heads around taking guidance from a fresh-faced 20-year-old millennial at the spa-like dispensary which is currently the norm at most dispensaries, who likely knows much more than even most medical professionals. It seems it will take even longer in Congress to understand the potential benefit of cannabinoids from a medical standpoint especially with the present opioid epidemic. Countries in Europe have far surpassed the United States when it comes to cutting-edge treatments. Perhaps, it will take even longer for the medical community to see the medical potential with their exposure to the sinister side of tetrahydrocannabinol seen in patients in the ER for non-medical reasons, which may be one of the most challenging stumbling blocks.

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Introduction/Disclaimer

References:

  1. Ghandhi, et al, “Systemic review of the potential role of cannabinoids as anti-proliferative agents for urological cancer,” Can. Urol. Assoc. J., 2017, May,-April., 11(3-4):E138-E142.
  2. Devinsky, et al, “Cannabidiol in patients with treatment-resistant epilepsy: an open-label interventional trial,” Lancet Neurology, 2016, Mar., 15(3):270-280.
  3. Petzke, et al, “Efficacy, tolerability, and safety of cannabinoids for chronic neuropathic pain: a systemic review of randomized controlled studies,” Schmerz, 2016, Feb., 30(1):62-88.
  4. Rajan. et al, “Gingival stromal cells as an in vitro model: cannabidiol modulates genes linked with amyotrophic lateral sclerosis,” Journal of Cellular Biochemistry, 2017, Apr., 118(4):819-828.
  5. ElSohly, et al, “Cannabinoids in glaucoma II: the effect of different cannabinoids on intraocular pressure on rabbits,”Current Eye Research, 1984, Jun., 3(6):841-50.
  6. Jarvinen, T., “Cannabinoids in the treatment of glaucoma,” Pharmacology and Therapeutics, 2002, Aug., 95(2):203-20.
  7. Carroll, et al, “9-Tetrahydrocannabinol exerts a direct neuroprotective effect in human cell culture model of Parkinson’s disease,” Neuropathology and Applied Neuropharmacology, 2012, Oct., 38(6):3535-547.
  8. Kaplan, et al, “Cannabidiol attenuates seizures and social deficits in a mouse model in Dravet syndrome,” Proceedings of the National Academy of Science, 2017, Oct.
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Tumor

The state of medical marijuana in urologic tumor burden control through inflammation reduction and reduction of tumor cell proliferation in cell cultures

IMG_0923_previewVirginia Thornley, M.D., Neurologist, Epileptologist

March 10, 2018

Introduction

Cannabinoids, which are cannabis plant-based non-synthetic medications including cannabidiol (CBD) and tetrahydrocannabinol (THC), are being used more frequently in palliative care to reduce the pain associated with end-stage cancer. In addition, it is well-established that it helps with lack of appetite found in cancer patients and reduces nausea and vomiting associated with many of the chemotherapeutic drug regimens (2), although current studies are needed given the newer chemotherapeutic agents available. Although there were more reported side effects using cannabinoids including euphoria, dizziness, dysphoria, and somnolence it is not clear if low dosages were used or what the ratio of cannabidiol to THC was used. It is well known that using higher doses of THC products will control the pain more adequately but at high doses may cause the side effect. Cannabidiol alone has no intoxication or euphoria and a low dose of cannabidiol combined with THC will ameliorate some of the side effects of THC.   Questions regarding its anti-tumor properties often arise which physicians managing patients with cancer are not prepared to answer. Since most of the studies are done in animal models and are often difficult to translate into the human model, research is needed with randomized clinical trials in the patient population. Currently, most anti-tumor literature is found in cell culture lines and extrapolated. The future is promising but large human studies are needed.

In renal cancer

Cannabinoids work through 2 receptors CB1 found in highest numbers in the brain and CB2 which is predominant in the immune system. In renal cancer, the CB1 receptor is found to be lower in number which may suggest that a reduced number of cannabinoid receptors leads to less control over the proliferation of tumor cells. There is a high concentration in the proximal convoluted tubule which suggests that a down-regulation may be associated with less inhibition of tumor cell proliferation (1). In another study, CB1 receptors were similar in chromophobe tissue lines were similar to renal cells with no tumor. This may serve as a diagnostic tool for differentiating it from clear cell tumors. It is often difficult to differentiate between the two. Chromophobe tumors have the same number of CB1 receptors while clear cell carcinomas have less CB1 receptors. This is important from the histological and diagnostic standpoint (1).

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In prostatic cancer

In prostate cancer, some mechanisms suggested through studies include working through phosphatase induction. It was found that CB1 and CB2 are expressed during later stages of prostatic cancer. Treatment of prostate cancer culture cells with cannabinoids was found to reduce the multiplication of tumor cells, suggesting a role through apoptotic mechanisms. The effect was dependent on dosage. In another study, cannabinoids were found to increase cytokine IL-6 in prostate cancer that is androgen resistant. This suggests that CB2 agonists may play an important role in reducing epithelial cell proliferation and may lead to a means to treat prostatic cancer (1). More studies are needed to elucidate mechanisms leading to treatment of prostatic cancer.

In bladder cancer

There is much evidence that inflammation found in cancer may lead to the metastatic stage. Cancer can lead to a pro-inflammatory state inducing cytokine and growth factor release leading to the environment conducive to metastasis and invasion of cancer cells into other tissues. In one study of the CB1 and CB2 receptors, it was found that activation of CB1 receptors played an important role in regulating tumor cell proliferation while CB2 was important in influencing an inflammatory state (1). Further studies are needed to further elucidate the mechanisms of cannabinoids on bladder cancer.

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Introduction/Disclaimer

Reference

  1. Ghandhi, et al, “Systemic review of the potential role of cannabinoids as anti-proliferative agents for urological cancer,” Can. Urol. Assoc. J., 2017, May,-April., 11(3-4):E138-E142.
  2. Smith, et al, “Cannabinoids for nausea and vomiting in adults receiving chemotherapy,” Cochrane Database Syst. Rev., Nov., 12(11):CD009464. doi: 10.1002/1465
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