Cannabinoids: potential role in the detection and reduction of pancreatic tumor load in pre-clinical studies
Virginia Thornley, M.D., Neurologist, Epileptologist
@VThornleyMD
August 1, 2018
Introduction
Cannabinoids are gaining more recognition in treatment not only of pain, seizures and mood disorder but also in a wide variety of conditions. There have been 3 decades of pre-clinical research studying the mechanisms as it relates to the different organ systems. There has been an exponential increase in cannabinoid research especially in light of the demand by grassroot movements for it availability in treating a wide variety of conditions.
As more and more physicians start to recommend it, more symptoms are coming to light which can be ameliorated with medical cannabis. One of the most sought after answer is the deadliest of diseases which is cancer. This seeks to study the mechanisms by which cannabinoids may play a role in reduction of tumor load.
Studies
There are many studies demonstrating the involvement of the endocannabinoid system in modulating the pathogenesis of tumors.
There are no published human clinical trials using cannabinoids in the treatment of the actual underlying pancreatic cancer. Cannabis is labelled under the schedule 1 classification, with that comes the difficulty with procuring the agent because of the bureaucracy and legal red tape that accompanies it. Regardless, there has been an exponential increase in pre-clinical studies in in vitro and in vivo studies.
Detection of pancreatic duct cancer using a CB2 probe
A study showed that the CB2 receptor is highly expressed in pancreatic duct cancer which seems to correlate with the aggressiveness of the tumor (1). One study reports on using fluorescence imaging on pancreatic duct cancer using an NIR (near infrared) CB2 receptor targeted probe (2). The study found a high level of expression of CB2 receptors in patient samples with pancreatic cancer compared to normal pancreatic tissue. This is significant because it gives information on a specific target for diagnostic and treatment purposes.
Cannabinoid involvement in autophagy through the AMPK pathway
In one study the cannabinoid receptor ligands were discovered to cause autophagy and activate AMPK in pancreatic cancer. In previous works by the same authors, cannabinoids were found to increase the radical oxygen species. In another study ROS was found to interact with the mitochondria where ATP is produced. AMP is upregulated instead leading to AMPK production which reduces mTOR1c and leads to an increase in autophagy and reduction of cell growth (3).
Possible therapeutic role of CB1 and CB2 receptor ligands on pancreatic cancer
In another study using pancreatic cancer cell lines Panc1, 2 cannabinoid receptor ligands were applied to study the mechanisms of cannabinoids and its possible anti-tumor effect. Cannabinoid ligands GW405833 and arachidonoyl cyclopropramide. The study showed that the cannabinoid ligands were involved in the down-regulation and up-regulation of proteins associated with regulation of cell growth and their energy metabolism. This could be a potential target for therapeutic approaches in pancreatic cancer (4).
Synergistic responses occur when CBD is combined with radiation
Cannabidiol can augment the tumor killing potential when combined with radiation therapy in pancreatic cancer which was studied under in vitro studies. Synergistic responses were noted when 5 micrograms of CBD was combined with 4Gy of radiation therapy in a clonogenic assay. In the same study using mice, there was increased survival in mice with pancreatic tumor using CBD compared to a control cohort. When CBD was added with SRB or smart biomaterials (agents which are sensitive to environmental factors that allow delivery of other agents in this case CBD to the tumor cells) the mice survived compared to the control cohort with just CBD application alone. This study demonstrates that CBD in conjunction with radiation therapy enhances the tumor killing properties in the treatment of pancreatic cancer (5).
SRB’s or smart radiotherapy biomaterials allow the insertion of payloads which allow the abscopal effects of radiation therapy thereby boosting its results (6). Abscopal refers to the idea that radiation treatment can affect tumors distant from the area treated.
In summary
While there may be a dearth of human clinical trials using cannabinoids for treatment in pancreatic cancer, the pre-clinical studies demonstrate that the endocannabinoid system may play a potential role in the mechanisms, diagnosis and treatment of pancreatic cancer, one of the deadliest tumors, and should not be discounted. More studies are needed especially human clinical trials.
References
1. Carracedo, A., Gironella, M., Lorente, M., Garcia, S., Guzman, M., Velasco, G., Iovanna, J.L. Cannabinoids induce apoptosis of pancreatic tumor cells via endoplasmic reticulum stress-related genes. Cancer Res. 2006, Jul, 66(13):6748-55
2. Guo, X., Ling, X., Du., F., Wang, Q., Huang, W., Wang, Z., Ding, X., Bai, M., Wu, Z. Molecular imaging of pancreatic duct adenocarcinoma using the type 2 cannabinoid targeted near-infrared fluorescent probe. Transl Oncol. 2018, Jul. 11(5):1065-1073
3. Dando, I., Donadelli, M., Costanzo, C., Dalla Pozza, E., D’Alessandro, A., Zolla, L., Palmieri, M. Cannabinoids inhibit energetic metabolism and induce AMPK-dependent autophagy in pancreatic cancer cells. Cell Death Dis. 2013, Jun 13, 4 e664
4. Brandi, J., Dando, I., Palmieri, M., Donadelli, M., Cecconi, D. Comparative proteomic and phosphosproteomic profiling of pancreatic adenocarcinoma treated with CB1 and CB2 agonists. Electrophoresis. 2013, May, 34(9-10):1359-1368
5. Moreau, M., Yasmin-Karim, S., Kunjachan, S., Sinha, N., Gremse, F., Kumar, R., Fan Chow, K., Ngwa, W. Priming the abscopal effect using multifunctional smart radiotherapy biomaterials loaded with immunoadjuvants, Front Oncol 2018, 8:56
6. Yasmin-Karim, S., Moreau, M., Mueller, R., Sinha, N., Dabney, R., Herman, A., Ngwa, W. Enhancing the therapeutic efficacy of cancer treatment with cannabinoids. Front Oncol 2018 Apr 24 (8):114
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