Methylseleninic acid induces lipid peroxidation and sensitizes head and neck cancer cells to radiation therapy

The success of treating cancer is frequently limited by damage to non-cancerous cells. Selenium is an essential micronutrient that sensitizes cancer cells to therapy while protecting normal cells. The manner in which this sensitization occurs is not well understood. However, selenium can be delivered in many forms, which tend to exhibit different effects.

This study investigated one particular selenium compound, methylseleninic acid (MSA), and how it impacts head and neck squamous cell carcinoma (HNSCC) cells. Results indicate that MSA can initiate a toxic chain reaction, referred to as lipid peroxidation (LPO). Inhibiting this chain reaction protected cancer cells from MSA-induced toxicity. MSA was found to be more toxic to HNSCC cells than similar selenium compounds, and it also rendered them more sensitive to radiation. MSA also depleted the cancer cells of glutathione, an essential cellular antioxidant. However, replenishing the glutathione pool in the cancer cells resulted in greater sensitivity to MSA rather than protection. Combining glutathione and MSA in the absence of cells resulted in an increased rate of disappearance of oxygen, which suggests the formation of reactive oxygen species, many of which are capable of inducing LPO.

Overall, this research suggests that selenium, and MSA in particular, is a promising addition to current therapy options for cancer patients. Sensitizing cancer cells to radiation helps to improve cure rates, while reducing debilitating side effects. More work is needed to better understand how MSA affects normal cells, to ensure that it doesn’t sensitize them as well.