Cannabidiol (CBD) selectively reduced activity and adhesion in human breast cancer cells while stimulating activity in non-tumor breast cells, according to a new laboratory study.
The study, published in the September issue of Folia Veterinaria, was conducted by researchers at the University of Veterinary Medicine and Pharmacy in Košice, Slovakia. Researchers said the findings provide preliminary evidence that CBD may have selective effects on tumor cells while having distinctly different effects on healthy cells.
Researchers compared MCF-7 cells, a human estrogen receptor-positive breast cancer cell line, with MCF-10A cells, a non-tumorigenic human breast epithelial cell line.
The cells were exposed to CBD concentrations of 2.5, 5, 10 and 20 micromolar for up to 72 hours. Researchers measured metabolic activity using an MTS assay and continuously monitored cell adhesion and proliferation using a real-time xCELLigence system.
Among the non-tumor MCF-10A cells, CBD increased metabolic activity at every concentration and time point tested, with particularly strong effects after 24 and 48 hours. Increased cell adhesion was also observed after 72 hours.
The breast cancer cells responded differently. At 20 micromolar, CBD significantly reduced metabolic activity in MCF-7 cells after 24 and 48 hours. Cell adhesion was significantly reduced at every concentration tested and at all three time points, with the largest reductions occurring after 48 hours.
Researchers also found statistically significant differences between cancer and non-tumor cells across all CBD concentrations for metabolic activity after 48 and 72 hours. Significant differences in adhesion were similarly observed across every tested concentration after 48 and 72 hours.
The two methods used to measure cellular responses were strongly correlated, with a Pearson correlation coefficient of 0.7768.
“The results of our study demonstrated a selective antiproliferative effect of CBD in a concentration-dependent manner on the MCF-7 mammary tumour cell line compared to the control,” the researchers wrote.
The largest differences emerged after longer exposure. After 72 hours, researchers reported both suppression of proliferation in the cancer cells and increased proliferation-related activity in the non-tumor cells.
The authors said the findings add to previous research suggesting CBD may affect cancer cells differently from healthy cells. Potential mechanisms identified in previous studies include apoptosis, oxidative stress and changes in cell migration, although those mechanisms were not directly tested in the new experiment.
Researchers cautioned that the study examined only one cancer cell line and one non-tumor cell line and did not involve humans or live animals. The study was conducted partly in the context of veterinary oncology, with the researchers noting similarities between human breast cancer and mammary tumors in companion animals.
“In our experiment, CBD demonstrated increased metabolic activity and adhesion in non-tumour MCF-10A cells, while inhibiting these parameters in tumour MCF-7 cells,” the researchers concluded.
They said additional studies involving more cancer types, veterinary cell lines and eventually animal models will be needed before the findings can be translated into clinical treatment.
