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. © 2007 Humana Press Inc.