In this study, we show that cannabis extract treatment significantly down regulates protein expression of prostate CB1 and CB2. Meanwhile, Cannabis treatment not only suppresses the spheroid formation ability of prostate cancer cells but also down regulates pro-inflammatory cytokine IL-6 and chemokine IL-8, decreases secreted protein and mRNA expression of prostate-specific antigen and VEGF levels. Our overall findings support that cannabidiol may possess anti-inflammatory, anti-CSC effects, and down regulate both cannabinoid receptors CB1 and CB2, leading to their anticancer and chemosensitizing effect against prostate cancer. Prostate cancer is the most frequently diagnosed cancer in western males . The progression of most of the cancers including prostate cancer may be a result of defects in cell cycle and apoptotic machinery. Thus, the agents which can modulate apoptosis in cancer cells may be useful in the management and therapy of cancer. Hence, there is a need to develop novel targets and mechanism-based agents for the management of prostate cancer.
One of the most exciting and promising areas of current cannabinoid research is the ability of these compounds to control the cell survival/death decision . In this study, we found that compared with PrEC cells, the expression levels of both cannabinoid receptors CB1 and CB2 were significantly higher in human prostate cells LNCaP, DU145, PC3 . These data suggest that CB1 and CB2 receptors could be targets for treatment options for prostate cancer. We also found that cannabis extract treatment of LNCaP and PC3 cells resulted in a decrease of cell viability as determined by MTS assay at varying doses & Figure 8), suggesting the involvement of both CB1 and CB2 in the anti-proliferative action of cannabinoids. Treatment of LNCaP cells with varying doses of cannabis extract resulted in down regulation of mRNA expression of CB1 and CB2 implicating cytopathic effect of cannabis extract on PCa cells . Apoptosis is a physiological and discrete way of cell death and is regarded to be an ideal way of cell elimination. In this study,self watering stake we also observed an increase in apoptosis of LNCaP cells by treatment with cannabis extract and this was confirmed by flow cytometry & Figure 6). The observation could be useful for the management of human prostate cancer. Androgens are essential for the growth, differentiation, and functioning of the prostate as well as in increasing prostate cancer development .
Hence, elimination or reducing the androgen receptor in prostate cancer should help in treating this neoplastic disease. We further studied the effect of cannabis extract on androgen receptor mRNA expression and its subsequent effect on PSA production. Our results indicate that cannabis extract treatment significantly decreases androgen receptor mRNA expression ) in LNCaP cells. PSA is an androgen receptor -regulated serine protease produced by prostate epithelial cells , and is the most widely employed marker in the detection of early prostate cancer. Therefore, agents which could reduce PSA levels may have important clinical implications for prostate cancer. Earlier studies reported that PSA is primarily regulated by androgens . Increased PSA level is used extensively as a biomarker of prostate diseases including prostatitis, benign prostatic hypertrophy, and prostate cancer. It is reported that in LNCaP cells, androgens regulate PSA glycoprotein expression and mRNA via androgen receptor . Our studies show a significant decrease in intracellular mRNA ) as well as secreted levels of PSA ) by cannabis extract treatment of cells, suggesting that cannabinoid receptor agonists may be exploited to prevent prostate cancer progression.
VEGF is a ubiquitous cytokine that regulates embryonic vasculogenesis and angiogenesis. Normal prostate epithelium expresses low levels of VEGF, whereas increased levels are reported in prostate carcinoma . Studies have shown that cannabinoid treatment markedly reduced the expression of VEGF in gliomas, the most potent proangiogenic factor and also of angiopoietin 2, which contributes to the angiogenic process by preventing vessel maturation . Our results showed that treatment of LNCaP with cannabis extract inhibits VEGF mRNA expression in LNCaP cells ). Chronic inflammation has been linked to various steps in tumor formation, including cellular transformation, proliferation, invasion, angiogenesis, and metastasis . Among the inflammatory cytokines, interleukin 1 , IL-6, IL-8, and IL-10 have been reported as present in the prostate cancer cells , indicating the significance of these inflammatory factors in prostate cancer progression. Therefore, controlling inappropriate inflammation would appear to be one strategy that might help control cancer progression.