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.