Abstract
The E2F-1 transcription factor is post-translationally modified and stabilized in response to various forms of DNA damage to regulate the expression of cell-cycle and pro-apoptotic genes. The sustained overexpression of E2F-1 is a characteristic feature of gastric cancer. In this study, we investigated the role of short hairpin RNA (shRNA) targeting E2F-1 gene on human gastric cancer MGC-803 cell growth in vivo, and preliminarily revealed the mechanism. Thus, we constructed recombinant pGCSIL-GFP-shRNA-E2F-1 lentiviral vector to knock down E2F-1 expression in human gastric cancer MGC-803 cells in vivo, and studied the effect of E2F-1 shRNA on growth of MGC-803 tumor and evaluated its treatment efficacy. Our data demonstrated that in a mouse model of established gastric cancer, intratumor injection of lentiviral shRNA targeting E2F-1 definitely decreased the endogenous E2F-1 mRNA and protein expression in MGC-803 tumor, and inhibited tumor growth and promoted tumor cells apoptosis. Moreover, we found that E2F-1 shRNA increased the expression of phosphatase and tensin homolog (PTEN), activated caspase-3 and caspase-9, and suppressed nuclear factor (NF)-κB expression in tumor tissue as determined by reverse transcription (RT)-PCR and western blotting. In summary, shRNA targeting of E2F-1 can effectively inhibits human gastric cancer MGC-803 cell growth in vivo and may be a potential therapeutic strategy for gastric cancer.
Highlights
Despite the decline in its incidence in the past few decades, gastric cancer remains the second most common cause of cancer-related deaths worldwide, and about two-thirds of gastric cancer cases occur in developing countries, and 42% in China alone (Parkin et al, 2005; Amiri, 2011)
Positive clones were confirmed by DNA sequence analysis and demonstrated that short hairpin RNA (shRNA) coding frames and frame sequences were correct, which indicated that the recombinant pGCSIL-green fluorescent protein (GFP)-shRNA-E2F-1 and pGCSIL-GFP-shRNA -NC plasmids were constructed successfully
The relative tumor volume of the Lv-shRNA-E2F-1 mice was significantly smaller than that of the control groups (P < 0.05) at 12 days after tumor injection, whereas no difference was found between the Lv-shRNA-NC and PBS groups (P > 0.05) (Figure 2B)
Summary
Despite the decline in its incidence in the past few decades, gastric cancer remains the second most common cause of cancer-related deaths worldwide, and about two-thirds of gastric cancer cases occur in developing countries, and 42% in China alone (Parkin et al, 2005; Amiri, 2011). It is necessary to find a new way to inhibit cancer cell growth effectively and avoid the side effects of drugs or radioactivity. Gene-targeting therapies have proved to be a promising way to achieve this goal. Dysregulation of gene expression is integral to the neoplastic process, and there is compelling evidence implicating upregulation or downregulation of multiple genes in the development and progression of gastric cancer. The E2F family of transcription factors can control the transcription of a group of genes that are normally regulated for cell proliferation and cell-cycle progression (Polager and Ginsberg, 2008). E2F-1, as a member of this gene family, is crucial for E2F-dependent apoptotic program (Lazzerini Denchi and Helin, 2005)
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