A Mild Keratin 1 Decrease Leads to Cell Death and Increased Oxidative Stress in B16-F10 Melanoma Cell Lines

Keratins play multiple significant biological roles in epithelium. K1 / keratin 10 (K10) heterodimer is a hallmarker for keratinocyte differentiation. While keratins are absent in normal melanocyte, keratins have been found in both melanoma cell lines and human melanoma. The biological significance of the keratins in melanoma cells has remained unclear. In our current study we applied K1 siRNA to investigate the biological significance of the K1 in B16-F10 melanoma cells. We found that as low as a 16% decrease in the K1 level led to significant increases in both apoptosis and necrosis of the cells. Moreover, the mild K1 decrease led to significant increases in both dichlorofluorescein (DCF) and ethidium signals - two indicators of oxidative stress - in the cells. Collectively, our findings have provided the first evidence indicating both a critical role of the K1 in maintaining the survival of melanoma cells and an important role of the K1 in modulating the oxidative stress state of the cells. These findings have exposed new functions of keratins in cancer cells, suggesting that K1 may become a novel therapeutic target for melanoma.