Prevention of Cell Proliferation Signaling Via RNA Interference of c-myc Gene Expression in Colon Cancer In-vitro

Abstract

Colon cancer is a cancer begins in the large intestine (colon). Its aggression is due to late diagnosis, so poor prognosis and higher mortality rates are reported. Colon cancer has become a thorny research area that requires more examination of cellular pathways involved in its emergency. Based on this, we sought to check the biological role of cMyc in colon cancer cell proliferation through targeting its expression by a respective siRNA using CaCo-2 cell lines. Notably, the cytotoxic potential of cMyc knockdown was monitored by cell imaging using an inverted microscope, the production of lactate dehydrogenase (LDH) and viability of the transfected cells using MTT assay. The relative gene expression of c-myc and other related factors such as Raf-1 was investigated using quantitative real-time PCR (qRT-PCR). ELISA assay has been used to achieve the production of pro and anti-inflammatory cytokines released from transfected cells. Interestingly, the transfection with a new designed siRNA antagonist cMyc markedly decreased CaCo-2 cell viability rate in a dose-dependent manner compared with the transfection with specific siRNA antagonist Luciferase gene, which served as control. Likewise, number of survived cells significantly reduced following transfection with siRNA against c-myc, while the relative production of LDH significantly increased. Importantly, the cytotoxic effect of the transfection protocol showed neglected influence in normal colon epithelial cells (NCM-460 cell lines) indicating the selective regulation of colon cancer cell proliferation by transfection with siRNA targeting c-myc. Noteworthy, the knockdown efficiency of c-myc showed more than 80% inhibition of its expression in CaCo-2 cells transfected with the siRNA antagonist c-myc indicated by qRT-PCR. The relative gene expression of Raf-1 significantly decreased in c-myc knockdown cells, while the relative expression of both P53 and Caspase 3, as cell death indicators, significantly upregulated compared with control-transfected cells. Furthermore, the transfection with siRNA targeting c-myc markedly increased the production of interleukin 1 alpha (IL-1α ) and IL-1β, as pro-inflammatory cytokines, while decreased the production of IL- 4 and IL-10, as anti-inflammatory cytokines. These data provide evidence for the involvement of c-myc gene expression in colon cancer cell proliferation and immune response during cancer development.