Abstract 4035: Cannabidiol inhibits the long-term survival of a variety of cancers
Authors: Emily Seltzer, Andrea Watters, Dong Zhang
Journal: Cancer Research (2020)

Abstract Cannabis has resurfaced as a natural alternative or adjunctive treatment for a variety of chronic conditions, such as anorexia in patients with the AIDS wasting syndrome and chemotherapy-related nausea and vomiting. Exogenous cannabinoids, such as Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), are found in the cannabis sativa plant. CBD has been shown to have anti-proliferative and pro-apoptotic effects in addition to preventing invasion and metastasis of various cancer cells. Such effects of CBD have been shown in certain cell lines of breast cancer, leukemia, glioma, small cell lung cancer, and colorectal cancer. Currently, the mechanism by which CBD exerts its effects are not fully understood. Here we have investigated CBD's effects on the long-term viability and mechanisms of cell death in a variety of cancer cell lines. Cancer cell lines of osteosarcoma (U2-OS), adenocarcinoma of the cervix (HeLa 1.2.11), metastatic breast cancer (MDA-MB 231), large cell lung carcinoma (H460) and malignant melanoma (A375) were plated on 12-well plates. 100% pure CBD isolated from cannabis sativa (generously provided by America's Finest CBD) was dissolved in ethanol and added directly to growth medium at various concentrations to determine the optimal dose in which the cells could no longer maintain viability. After 7-10 days, cells were stained with crystal violet. The blue dye was later extracted, quantified with a spectrometer, and dose response curves were plotted. For PARP cleavage analysis, cells were exposed to a certain concertation of CBD concentration and collected over 24-hour intervals. In addition, we have also performed RNA sequencing (RNA Seq) analysis using the melanoma cell line, A375, in an attempt to uncover the molecular mechanism of cell death induced by CBD treatment. Our long-term viability analysis demonstrate that a dose dependent response was present for each cell line exposed to CBD. We showed that CBD allows for a dose dependent killing in a variety of cancer cell lines, including large cell lung carcinoma, metastatic breast cancer, malignant melanoma, cervical carcinoma and osteosarcoma. IC50 of each cell line was determined as follows: A375 - 2.45μM, H460 - 8.47 μM, MDA-MB-231 - 8.35 μM, HeLa1.2.11 - 4.1 μM, and U2OS - 4.63 μM. The more aggressive cancer cell lines H460 and MDA-MB-231 required relatively higher dosages of CBD to kill the cells. A375, a malignant melanoma cell line, is the most sensitive cancer cell line to CBD tested so far. Apoptosis as a mechanism of cell death was confirmed with the presence of PARP cleavage in A375, H460, and MDA-MB-231 cell lines. Preliminary RNA Sequencing results suggest that heightened endoplasmic reticulum (ER) stress response in CBD treated cells is likely the cause of cell death. In summary, CBD demonstrates dose-dependent killing effects on a wide range of cancer cell lines, many of which have demonstrated a mechanism through apoptosis. Intriguingly, one of the melanoma cell lines is the most sensitive cancer cell line tested so far. Our RNA Sequencing analysis showed that CBD treatment induces a drastic increase of ER stress response, suggesting a potential mechanism of CBD induced apoptosis in cancers. In the future, we plan to develop a CBD cream and test its efficacy on preventing and/or treating skin cancers. Citation Format: Emily Seltzer, Andrea Watters, Dong Zhang. Cannabidiol inhibits the long-term survival of a variety of cancers [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4035.