Cannabidiol: assessing activity in ovarian and endometrial carcinoma cell lines

Objectives: Cancer patients use cannabidiol (CBD) for chemotherapy and cancer symptoms, though recognition of CBD by and its effect on endometrial cancer (EnC) and epithelial ovarian cancer (EOC) are not established. We sought to test expression of cannabidiol receptor 1 (CB1) and cannabidiol receptor 2 (CB2) on EnC (ECC1) and EOC (Kuramochi, OVCar-3, and murine ID8 (p53/BRCA2 negative)) cell lines. We further explore EnC (ECC1) and EOC (Kuramochi) cell proliferation when exposed to different concentrations of CBD alone, and with cytotoxic chemotherapies carboplatin (CP) and paclitaxel (PT). Methods: We assessed CB1 and CB2 receptor expression in the four cell lines by flow cytometry using primary mouse monoclonal antibodies against these receptors followed by detection using a FITC-conjugated secondary antibody. ECC1 and Kuramochi cells were kept in RPMI media with 10% bovine serum + 1% penicillin/streptomycin. We passaged cells when >90% confluent by adding trypsin-EDTA, incubating at 370 C for 3 minutes, then spinning down with media to harvest cell pellets. Cells were re-suspended in media, apportioned to 96 well plates, and incubated at 370C for 24 hours. CBD (Cayman Chemical) was suspended in DMSO per manufacturer then used to treat cells for72 hours at different concentrations (2.5-50 mM). We also treated cells with CBD and CP and/or PT, choosing concentration gradients for combinations based on assays with single agents. MTT was added and cells were incubated at 370 C for 3 hours. The media and MTT were removed and DMSO was added to dissolve formazan crystals. Optical density (OD) at 570 nm was calculated for plates using SoftMaxPro version 6.2.2. ODs were used to calculate inhibitory concentration for 50% cell death (IC50) for CBD alone, CBD+CP, CBD+PT and CBD+CP and PT. Results: All four cell lines tested had measurable CB1 but no CB2 receptor expression on flow cytometry. Kuramochi and ECC1 had decreased proliferation after 72 hours of CBD exposure. ECC1 IC50 was 2.5-5 mM CBD concentration; Kuramochi IC50 was 15-20 mM CBD. Nearly all ECC1 growth was inhibited at concentrations 10 mM or greater. Kuramochi proliferation was 15% that of controls at concentrations of 40 and 50 mM CBD. ECC1 had expected dose-dependent decreased in proliferation when treated with CBD in combination with CP or PT. Kuramochi as a platinum resistant cell line demonstrated decreased proliferation with CBD alone and in combo with PT but not with CP. Download : Download high-res image (108KB) Download : Download full-size image Conclusions: ECC1 and Kuramochi demonstrated decreased proliferation in the presence of CBD, with combination studies having similar trends. CB1 likely mitigates proliferation effect of CBD on Kuramochi and ECC1. OVCAR3 and ID8 cells have CB1; further experimentation will establish CBD treatment effect on these lines. Our studies suggest a beneficial anti-proliferative effect of CBD as a single agent or when used in combination with CP or PT, an important finding considering the use of CBD by gynecologic cancer patients for relief from cancer and chemotherapy side effects.