FIG. 1.

Telomerase promoter characterization. (A) Luciferase reporter activity of the hTERT core promoter cloned upstream of the luciferase gene and transfected into a panel of eight human tumor cell lines. qPCR analysis of endogenous hTERT RNA (B) and hTER RNA (C) is shown for the same panel of cell lines as in (A), with the addition of human hepatocytes. RNA levels were set relative to that of MCF-7 cells. hTERT mRNA was undetectable in BT-20 cells and in primary human hepatocytes. Data shown represent means + SD for n = 3 replicates. (D) Western blot showing E1A expression in MCF-7/4HC, MDA-MB-231, U251, and A549 cells after transfection with pGL3-hTERT-E1A. Fifteen micrograms of protein was loaded for the 293T cell E1A-positive control; 50 μg was loaded for each of the transfected cell lines. The three bands reflect multiple transcripts. No E1A was present in untransfected cell line controls (data not shown).