Photobiomodulation mitigates doxorubicin resistance in MDA-MB-231 breast cancer cells: a promising avenue for overcoming chemoresistance.

One of the formidable challenges that may emerge in patients with breast cancer is drug resistance which is highly correlated with failure in cancer therapy and, as a result, poorer prognosis. Thus, developing novel approaches to overcome this undesirable event has always been a hot topic in the field of cancer. Photobiomodulation (PBM), also known as low-level laser therapy, is one such approach that has recently been introduced as a promising modality in clinical settings with interesting anti-tumor properties. Moreover, PBM has been considered a possible candidate to be employed in conjunction with conventional modalities such as chemotherapy. The present study investigated the potential effects of PBM at two wavelengths of 630 nm and 980 nm on chemoresistance in breast cancer MDA-MB-231 cells, which previously acquired resistance to doxorubicin (DOX) through 12 passages. Findings proposed that PBM, in conjunction with DOX, led to a reduction in the viability of resistant MDA-MB 231 cells as was evidenced by decreased IC₅₀ values of DOX across different groups. Furthermore, gene expression studies demonstrated that PBM inhibited the overexpression of some of the important resistance-related genes, including SOX9, MDR1, NRF2, TGF-β, and ABCC1. Although both wavelengths had considerable efficiency, at 630 nm, PBM performed better in overcoming DOX resistance. Overall, the present study suggests that PBM might play a promising role against breast cancer via reducing chemoresistance which, indeed, necessitates further research to better understand its mechanisms and clinical potential for translation.