Telomerase is a specialized nucleoprotein enzyme complex that maintains the telomere length. The telomerase
reverse transcriptase (TERT) is the catalytically active component of the telomerase complex. In humans, the protein
component (hTERT) and RNA component (hTR) are found to differentially express in cancer cells. In contrast
to differentiated cells, most of the cancer cells overexpress hTERT, which is needed to maintain the proliferative
potential of cells. The overexpression of telomerase is not proportionate to telomere length in cancer cells, suggesting
that the immortalizing phenotype can bemediated through other factors in addition to telomere length.
To investigate the role of hTERT in immortalizing process, loss of gene function studies were carried out. Short
interfering RNA (siRNA) and short hairpinRNA (shRNA) against hTERT showed the reduction of hTERT transcript,
reduction of telomerase activity and alteration of gene expression in HeLa cells.