PinX1, a novel target gene of p53, is suppressed by HPV16 E6 in cervical cancer cells.

The aberrant activation of telomerase is critical for the initiation and development of human cervical cancer, which is dependent on the activation of human telomerase reverse transcriptase (hTERT). Recently, Pin2/TRF1-interacting protein X1 (PinX1) has been identified as a suppressor of hTERT. It has been found that the telomerase is activated while the level of PinX1 is decreased in cervical cancer. However, the regulatory mechanism of PinX1 in cervical cancer cells remains unclear. In the present study, we demonstrated that the level of PinX1 is regulated by p53, and p53 functions as a transcriptional factor to directly activate the expression of PinX1 in cervical cancer cells. Moreover, we found that HPV16 E6 suppresses the expression of PinX1 via inhibiting p53 transcriptional activity, resulting in the enhancement of telomerase activity. This study not only for the first time shows that PinX1 is a novel target gene of p53 but also suggests that suppression of p53/PinX1 pathway may be a novel mechanism by which HPV16 E6 enhances the telomerase activity in cervical cancer cells.