Htert Expression Despite Dense Upstream Promoter Methylation

4981hTERT, which encodes the catalytic subunit of telomerase, is re-expressed in 80-95% of cancer cells allowing for telomere maintenance and unlimited cell growth. hTERT, like many human genes, contains a CpG island in its promoter region. Previous studies have examined a potential role for DNA methylation in the regulation of hTERT expression. Although the reports are conflicting, they suggest increased methylation in hTERT positive cancer cells and lack of methylation in normal hTERT negative cells. This is inconsistent with the general understanding that DNA methylation of promoter CpG islands is associated with gene silencing. Therefore, we examined this phenomenon in more detail by performing methylation specific PCR (MSP) and bisulfite sequencing of the hTERT promoter in 10 breast, lung, and colon cancer cancer cell lines. We examined a region from -650 to +150 base pairs from the …