The Effect of Overexpression of hTERT on Etoposide (VP-16)-Induced Apoptosis in Raji Cells

摘要

OBJECTIVE To explore whether overexpression of human telomerase reverse transcriptase (hTERT) in Raji cells can protect against etoposide (VP-16)-induced apoptosis. METHODS A Iipofectin-mediated gene transfection method was used to transfer the hTERT gene into Raji cells. The polymerase chain reaction enzyme-linked immunoassay was employed to determine telomerase activity. The expression levels of hTERT protein were assayed by immunofluores-cence using a fluoresce isothiocyanate label. Cell viability was determined using the trypan blue dye exclusion assay. Apoptosis was assessed by morphological observation and flow cytometry analysis. RESULTS The results showed that there was a marked increase in both mean fluorescence intensity of hTERT-protein-positive cells and telomerase activity in hTERT-transfected Raji cells (P < 0.05), but there was no difference in hTERT protein and telomerase activity levels between Raji cells and vector-transfected Raji cells (P > 0.05). There were more viable cells at 48 h and 72 h after treatment of hTERT-transfected Raji cells with 10 μmol/L VP-16 compared to either vector-transfected Raji cells and Raji cells (P < 0.05). Apoptosis rates at 72 h after treatment with 10 μmol/L VP-16 were 4.34 ± 1.03% in hTERT-transfected Raji cells, 33.21 ± 3.12% in vector-transfected Raji cells, and 31.63 ± 3.06% in Raji cells. There was a significant difference in the percentage of apoptotic cells between hTERT-transfected Raji cells and either vector-transfected Raji cells or Raji cells (P < 0.05). CONCLUSION Overexpression of telomerase by transfection of hTERT gene can protect against etoposide-induced apoptosis in Raji cells.