Effects of standardized Cannabis sativa extract and ionizing radiation in melanoma cells in vitro

Context: Melanoma causes the highest number of skin cancer-related deaths worldwide. New treatment methods are essential for the management of this life-threatening disease.

Aims: In this study, we investigated the efficacy of a standardized Cannabis sativa extract alone or in combination with single radiation dose (6 Gy) in B16F10 mouse melanoma cells in an extract dose-dependent manner.

Materials and methods: C. sativa extract at three concentrations (25, 12.5, and 6.25 μg/mL) alone for 72 h or in combination with radiation (24 h incubation after the extract treatment + 48 h incubation after exposure to radiation) were evaluated for cell viability of melanoma cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cells were also treated with 6.25 μg/mL extract alone for 72 h before analyzing C. sativa-induced cell death by flow cytometry.

Results: Administration of the extract alone or alongside radiation substantially inhibited melanoma cell viability and proliferation in the extract dose response-dependent manner. The inhibition of melanoma cell viability was paralleled by an increase in necrosis but not apoptosis when melanoma cells were treated with the extract alone. Radiation alone did not have any antiproliferative effects, and radiation also did not synergize antiproliferative effects of the extract when the extract and radiation were combined.

Conclusion: Our data suggest that C. sativa extract may have significant health and physiological implications for the treatment of melanoma. The results of this study also indicate that B16F10 mouse melanoma cells are radioresistant. Taken together, these findings may lead to the identification of new therapeutic strategy for the management of melanoma.