Signal Transducer and Activator of Transcription 3 (STAT3) Regulates Human Telomerase Reverse Transcriptase (htert) Expression in Human Cancer and Primary Cells

Signal transducer and activator of transcription 3 (STAT3) is a transcription factor that plays a critical role in cytokine and growth factor signaling and is frequently activated in human tumors. Human telomerase reverse transcriptase (hTERT) is also often overexpressed in tumor cells and mediates cellular immortalization. Here we report that STAT3 directly regulates the expression of hTERT in a variety of human cancer cells. Moreover, STAT3 activity is required for the survival of many human tumors, and hTERT expression contributes to the survival of STAT3-dependent tumor cells. In addition, we find that growth factors and cytokines stimulate hTERT expression in primary human cells in a STAT3-dependent manner. Thus, STAT3 is a key regulator of hTERT expression in both normal and tumor cells.