eIF3m expression influences the regulation of tumorigenesis-related genes in human colon cancer.

Abnormal regulation of gene expression is essential for tumorigenesis. Recent studies indicate that regulation of oncogene expression and neoplastic transformation are controlled by subunits of eukaryotic translation initiation factors (eIFs). Here we focused on eIF3 performing a pivotal role in protein synthesis and the differential expression of its subunits in cancer. The most uncharacterized non-core subunit eIF3m was confirmed to be highly expressed in human cancer cell lines and colon cancer patient tissues. By expression silencing with eIF3m-specific small interfering RNA (siRNA), we confirmed that eIF3m influences cell proliferation, cell cycle progression and cell death in human colon cancer cell line HCT-116. Using a ribonomics approach, we identified a subset of elF3m-influenced genes and showed that the expression of two highly represented tumorigenesis-related genes, MIF and MT2, were affected by eIF3m at the mRNA level. We also confirmed eIF3m-dependent regulation of MT2A downstream molecule CDC25A, which is necessary for cell cycle progression in HCT-116 cells. These results suggest that eIF3m mediates regulation of tumorigenesis-related genes in human colon cancer. Further investigations on tumorigenesis-related genes and their regulation by eIFs will provide clues for designing targeted therapy for cancer.