Telomerase expression in human somatic cells does not induce changes associated with a transformed phenotype

Expression of the human telomerase catalytic component, hTERT, in normal hu man somatic cells can reconstitute telomerase activity and extend their rep licative lifespan(1,2). We report here that at twice the normal number of p opulation doublings, telomerase-expressing human skin fibroblasts (BJ-hTERT ) and retinal pigment epithelial cells (RPE-hTERT) retain normal growth con trol in response to serum deprivation, high cell density, G1 or GZ phase bl ockers and spindle inhibitors. In addition, we observed no cell growth in s oft agar and detected no tumour formation in vivo. Thus, we find that telom erase expression in normal cells does not appear to induce changes associat ed with a malignant phenotype.