Interaction between omega 3 PUFA and UVB radiation: Photoprotective effect in normal and tumoral murine melanocytes?

- ALA was antiproliferative for B16F10 cells and had a minimal effect in Melan-a cells.
- ALA attenuated cell death caused by UVB in 48 h in both cell lines.
- The omega 6 PUFA LA was not able to protect the cell lines of the UVB effects.
- ALA did not alter ROS levels in both cells exposed to UVB radiation.
- ALA demonstrates a photoprotective effect in B16F10 and Melan-a cells exposed to UVB.

Omega 3 polyunsaturated fatty acids (omega 3 PUFA) are attracting a growing interest as potential adjuvants for cancer prevention and treatment. There is evidence about photoprotection in normal cells, but few previous studies have evaluated it in tumoral cells. Therefore, this study investigated the effect of α-linolenic acid (ALA) in normal murine melanocytic cells (Melan-a) and in tumoral murine melanocytic cells (B16F10) exposed to UVB radiation. Our results showed that ALA exhibited an antiproliferative effect in B16F10 cells, and had minimal effect in Melan-a cells, as demonstrated by MTT assay. On the other hand, the combination of ALA (7.5 μM) and UVB (0.01 J/cm2) showed a protective effect for both cell lines, Melan-a and B16F10. ALA and UVB combined or UVB alone induced an accumulation of cell lines at the S/G2/M phase. In addition, the combination of ALA and UVB, and UVB alone, both induced cell death in 24 h; and in 48 h, ALA attenuated this effect in both cells. Further to these findings, it was demonstrated that ALA did not alter ROS levels in both cells exposed to UVB radiation. The effect of an omega 6 PUFA, linoleic acid, under the same conditions of ALA were tested. It was not protective in either cell line. Therefore, our results can be very important since it was shown another role to an omega 3 PUFA as a photoprotective agent in a melanoma cell.