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cbd oil colon cancer

Conclusions: CBD BDS attenuates colon carcinogenesis and inhibits colorectal cancer cell proliferation via CB1 and CB2 receptor activation. The results may have some clinical relevance for the use of Cannabis-based medicines in cancer patients.

Methods: Proliferation was evaluated in colorectal carcinoma (DLD-1 and HCT116) as well as in healthy colonic cells using the MTT assay. CBD BDS binding was evaluated by its ability to displace [(3)H]CP55940 from human cannabinoid CB1 and CB2 receptors. In vivo, the effect of CBD BDS was examined on the preneoplastic lesions (aberrant crypt foci), polyps and tumours induced by the carcinogenic agent azoxymethane (AOM) as well as in a xenograft model of colon cancer in mice.

Purpose: Colon cancer is a major public health problem. Cannabis-based medicines are useful adjunctive treatments in cancer patients. Here, we have investigated the effect of a standardized Cannabis sativa extract with high content of cannabidiol (CBD), here named CBD BDS, i.e. CBD botanical drug substance, on colorectal cancer cell proliferation and in experimental models of colon cancer in vivo.

Results: CBD BDS and CBD reduced cell proliferation in tumoral, but not in healthy, cells. The effect of CBD BDS was counteracted by selective CB1 and CB2 receptor antagonists. Pure CBD reduced cell proliferation in a CB1-sensitive antagonist manner only. In binding assays, CBD BDS showed greater affinity than pure CBD for both CB1 and CB2 receptors, with pure CBD having very little affinity. In vivo, CBD BDS reduced AOM-induced preneoplastic lesions and polyps as well as tumour growth in the xenograft model of colon cancer.

Keywords: ?(9)-Tetrahydrocannabinol; Cancer cell growth; Cannabidiol; Cannabinoid receptors; Chemoprevention; Colorectal cancer.

To assess the ability of the CBD oils to reduce cell viability, we conducted cell death experiments as previously described for pure CBD [13]. The oils were diluted in DMSO such that the cells were treated with 10 μM CBD for each oil (oil content varied between 0.05 and 0.06%). There was again a cell-type specific effect of CBD oils to reduce cell viability observed in all 3 cancer types. Selected CBD oils were effective at reducing viability in SW480 and HCT116 CRC cells (Fig. 2a), 1205Lu melanoma cells (Fig. 2b), and T98G GBM cells (Fig. 2c), but not effective against the melanoma cell line A375M (Fig. 2b) or the GBM cell line U87MG (Fig. 2c). Interestingly, despite all the oils being diluted to the same CBD concentration, Oil A was consistently the most potent, while Oil C was always the least potent and never produced a statistically significant reduction in cell viability (Fig. 2). Indeed, not only was Oil C indistinguishable from control, Oil A was significantly better than Oil C at reducing cell viability in 4 of the 6 lines tested (statistical analysis not shown). The potency of Oil B was variable based upon cell line tested. To confirm these results, we purchased a different lot of oil from each company and found no significant differences in the ability to reduce cancer cell viability between lots (data not shown). The Oil A results were confirmed by trypan blue staining. Given the same results, these new preparations were not analyzed for CBD content.

Cells were treated as described above at varying concentrations of CBD or CBD Oil A (the most potent of the 3 oils based on viability analyses (Fig. 2)): 100, 56, 33, 18, 10, 3.3, 1.0, 0.33, and 0.1 μM. Viability was measured as described above and GraphPad Prism software (GraphPad Software; San Diego, CA, USA) was used to calculate IC50 values and to prepare semi-logarithmic dose-effect curves.

Oils for this study were specifically selected because the companies provided third party verification of their content; however, we verified their content through independent confirmatory testing. The testing laboratory was blinded to the identity of the oils. Only minor discrepancies were observed between the reported values and our analysis (Table 1; each oil was within 8% of their reported CBD concentration upon independent testing). The THC content for all 3 oils was below 0.3% (based on total mass of the oil), the maximum level allowed in the US for hemp-derived products. We also analyzed the oils for terpene content as shown in Table 2, this information was not provided by all of the companies, and therefore, only our data are provided. The 3 oils varied in color and so chlorophyll/carotenoid content was assessed spectrophotometrically (see online suppl. Table 1 [30, 31]; see for all online suppl. material). Additionally, 2 of the oils (Oil B and Oil C) listed fractionated coconut oil (or medium-chain triglyceride coconut oil) on the ingredient list, while Oil A was pure hemp oil.

Table 2.

A number of recent studies have highlighted that not all CBD oils are in agreement with their labels. With regard to CBD oil composition our findings is in agreement with a study by Urasaki et al. [38] that found oil composition in agreement with the manufacturer’s label. This is in contrast with other studies that have shown marked differences between the actual composition of CBD oil and what is stated on the label [39, 40]. This highlights a concern that, in this unregulated commercial environment, CBD composition is highly variable and that there is a need for regulatory control and government-sanctioned independent testing of commercial products. Additionally, the findings from Urasaki and colleagues regarding the ability of pure CBD versus CBD oils to downregulate PI3K/Akt/mTOR signaling in neuronal cells, parallel our results in that pure hemp oil (Oil A) was more potent in their studies than hemp oil that was diluted in coconut oil (Oils B and C) [38].

Our results – showing that there does not appear to be an entourage effect when comparing pure CBD to high CBD content hemp oils – are in contrast to a recent study in breast cancer cells that showed botanical drug preparations were more efficacious than pure THC at reducing cell viability [32]. We also conducted an experiment in which CRCs were treated with equal amounts of CBD and THC in media containing serum and did not see any further enhancement of the toxic effect of CBD alone (data not shown). However, there are several differences between our study and the study of Blasco-Benito and colleagues [32]. First, our study did not serum-starve cells, and this likely accounts for the difference in findings. Cannabinoids have been found to be greater than 90% bound to protein in blood samples from human pharmacokinetic experiments and so, in the absence of plasma proteins, the effective concentration of free drug will be much higher. In the present study, we chose to avoid serum starvation because it less accurately reflects the human system and renders the cells more fragile and sensitive to drug treatment [33-36]. Second, the 2 studies examined different principal cannabinoids; here, we examined the effect around CBD oil and attendant additional phytochemicals, and the former study focused on THC. Interestingly, their plant extract did not contain any CBD [32]. We have not observed an ability of pure THC to reduce viability in CRC cells [13], nor melanoma or GBM cells (data not shown). Several studies have reported that THC can reduce cancer cell viability; however, these studies were all performed in low or no serum conditions [10, 19, 21, 22]. In agreement with these studies, we did find that THC can reduce cell viability in CRCs to levels similar to CBD under no serum conditions (data not shown) and so, our findings are not in conflict. However, in the presence of serum, we do not see an effect of THC, and this is in agreement with a study that showed that cell viability of cancer cells in serum was not impacted by THC at concentrations less than 63.5 μM[37].

Sample dose response curves for CBD compared to CBD oil A. Cell viability was measured by MTS assay 48 h after treatment with CBD or CBD Oil A at 100, 56, 33, 18, 10, 3.3, 1.0 μM, 330 nM, and 100 nM: CRC line SW480 (a); melanoma cell line 1205Lu (b); and GBM cell line T98G (c). CBD, cannabidiol; CRC, colorectal cancer cell; GBM, glioblastoma.

CBD is more potent than CBD Oil A