Dose-dependent effects of yellow laser irradiation on Viability, apoptosis, and ROS generation in cell lines from breast cancer.

BACKGROUND: It is challenging to find effective breast cancer treatments as this disease is highly varied. But photobiomodulation therapy (PBMT) has shown promising results, specifically with the usage of yellow light. Even so, much work is still needed to understand its effect in cancer treatment. OBJECTIVE: The aim is to determine the effect of 589 nm yellow laser light (5-20 J/cm²) at various dosages on cellular activities like metabolism, cell death (apoptosis), and reactive oxygen species (ROS) production, focusing on MCF-7 (ER-positive) and MDA-MB-231 (triple-negative) human breast cancer cells. This is expected to explain the drivers of photobiomodulation. METHODS: The MDA-MB-231 and MCF-7 breast cancer cells are exposed continuously to yellow light at 5, 10, 20 J/cm2. After being exposed for 24 and 48 h, the cells' metabolic activity was measured using MTT assay. Apoptosis was measured using Annexin V-FITC/PI staining. ROS levels were measured using DCFH-DA assays. RESULTS: The dosage-based yellow light exposure substantially decreased metabolic activity and boosted cell death (apoptosis) in both breast cancer cells, more so in the MCF-7 cells than the MDA-MB-231 cells. After exposure, the ROS levels particularly for the MCF-7 cells rose substantially, suggesting the major role of oxidative stress. CONCLUSION: Yellow laser exposure triggers targeted cell death and cytotoxic effects in breast cancer cells, especially in ER-positive MCF-7 cells. The findings suggest that yellow laser PBMT is promising as a treatment approach for certain breast cancers.