hTERT transactivators from human gastric cancer

Abstract

In addition to its role in telomere maintenance, telomerase provides additional functions in tumorogenesis, DNA repair, and cell survival. Telomerase protects cells from apoptosis and necrosis, and stimulates growth. Furthermore, the overexpression of the catalytic subunit of telomerase (hTERT) may act as a hyperproliferative signal Upregulation of human telomerase reverse transcriptase (hTERT) transcription accounts for the immortalization of greater than 85% of all human tumor cells. However, the mechanism whereby hTERT expression is activated remains unresolved. Transcription initiation site was determined by 5`RACE and hTERT promoter was cloned by PCR from human genomic DNA. hTERT promoter and itrs deletion constructs were analyzed by transient transfection and firefly luciferase assay with transactivating candidate factors. Those factors were selected from the result of oligonucleotide microarrays of gastric cancer and confirmed by RT PCR. Each factors were cloned from human fetal cDNA library. These factors have variable transcriptional activity for hTERT promoter according to cellular context. The determinant for hTERT activation might be the interaction of several nuclear factors including Myc and E1AF.