E1A inhibits the proliferation of human cervical cancer cells (HeLa cells) by apoptosis induction through activation of HER-2/Neu/Caspase-3 pathway

Objective    This study is to investigate the inhibitory effect of E1A gene on the cell proliferation of HeLa cells and its mechanism related to apoptosis. Methods    MTT assay and soft agar colony formation assay were employed to justify the inhibition activity of E1A on the proliferation of HeLa cells transfected with E1A gene. Western Blot, RT-PCR and Real-time quantitative RT-PCR were used to detect the gene expression of E1A, HER-2/Neu and Caspase-3 in HeLa cells, respectively. The Caspase-3 activity was monitored by ApoAlert Caspase-3 Assay. The redistribution of cell cycles and apoptosis of HeLa cells regulated by E1A expression were evaluated by flow cytometry. Results    E1A expression significantly inhibits the cell proliferation and anchorage-independent cell growth of HeLa, with the respective highest inhibition rate of 40.7% and 43.4% (P < 0.01). HER-2/Neu expression in HeLa was significantly down-regulated by E1A, while the protein expression and activity of Caspase-3 was up-regulated by E1A expression. Flow cytometry revealed that E1A transfection in HeLa increased the cell number at G1 stage and simultaneously decreased the cell number at S stage. E1A transfection induced 8.71% of HeLa cells at apoptosis status. Conclusions    E1A significantly inhibits the cell proliferation of HeLa by the apoptosis induction through HER-2/Neu/Caspase-3 pathway. These results encourage us to continue an in-vivo study and preclinical development of LPD-E1A as a novel gene therapeutic agent for human cervical cancer.