Down-regulation of PTEN expression due to loss of promoter activity in human hepatocellular carcinoma cell lines.

Aim: To investigate the regulation of phosphatase and tensin homolog deleted on chromosome ten (PTEN) gene expression in human hepatocellular carcinoma (HCC) cell lines.

Methods: The mRNA and protein levels of PTEN were detected by Northern blot and Western blot in HCC cell lines, respectively. Plasmids containing different fragments of PTEN promoter with Luciferase reporter were constructed and transiently transfected into HCC cell lines to study the promoter activity. DNA analysis and RT-PCR were performed to detect the mutation of PTEN promoter and PTEN cDNA.

Results: Either protein or mRNA levels of PTEN in L02 cells (as a control) were significantly higher than that in HCC cell lines. The profile of PTEN promoter activity in 8 cell lines was closely correlated with levels of PTEN mRNA and PTEN protein. Furthermore, the sequence analysis of 8 cells lines showed no mutation in the region of PTEN promoter and PTEN cDNA.

Conclusion: PTEN expression is down-regulated in HCC cell lines probably due to loss of activity of PTEN promoter.