Linc-ROR promotes arsenite-transformed keratinocyte proliferation by inhibiting P53 activity

Linc-ROR is an oncogenic long non-coding RNA over-expressed in many kinds of cancer that promotes cancer cell proliferation. Arsenite is a determined carcinogen that increases the risk of skin cancer, but the carcinogenic mechanism of arsenite remains unclear. To explore whether and how linc-ROR plays a role in arsenite-induced carcinogenesis of skin cancer, we established arsenite-transformed keratinocyte HaCaT cells by exposing them to 1 μM arsenite for 50 passages. Then we examined the linc-ROR expression during the transformation and explored the effect of linc-ROR on the cell proliferation of arsenite-transformed HaCaT cells. We found that the linc-ROR level in HaCaT cells was gradually increased during arsenite-induced malignant transformation, and the activity of P53 was decreased, but the P53 expression was not significantly altered, indicating that linc-ROR may play a role in arsenite-induced HaCaT cell transformation that is associated with P53 activity but not P53 expression. We further demonstrated that linc-ROR down-regulation by siRNA significantly inhibited the cellular proliferation and restored P53 activity in arsenite-transformed HaCaT cells, suggesting that linc-ROR promotes proliferation of arsenite-transformed HaCaT cells by inhibiting P53 activity. Moreover, linc-ROR siRNA also down-regulated the PI3K/AKT pathway in arsenite-transformed HaCaT cells, and treatment with AKT inhibitor wortmannin restored P53 activity, implying that linc-ROR inhibits P53 activity by activating the PI3K/AKT pathway. Taken together, the present study shows that linc-ROR promotes arsenite-transformed keratinocyte proliferation by inhibiting P53 activity through activating PI3K/AKT, providing a novel carcinogenic mechanism of arsenite-induced skin cancer.