Knockdown of metadherin inhibits cell proliferation and migration in colorectal cancer

Metadherin (MTDH) is a multifunctional oncogene involved in tumor cell migration and metastasis through regulating a number of oncogenic signaling pathways in various human malignancies. Previous studies have demonstrated that MTDH is overexpressed in human colorectal cancer (CRC) and associated with cancer progression and a poor prognosis. However, the underlying mechanisms remain largely unknown. The present study investigated the expression and role of MTDH in CRC cells as well as the underlying mechanism of this. Western blot analysis and quantitative polymerase chain reaction were conducted to determine protein and mRNA expression of MTDH in three human CRC cell lines. A short hairpin RNA (shRNA) targeting MTDH was introduced into CRC HCT116 cells to stably inhibit MTDH expression. A Cell Counting Kit-8 assay, colony formation assay, Transwell assay and flow cytometry were used to investigate the effect of MTDH-knockdown on cell proliferation, migration, apoptosis and cell cycle arrest. Western blotting was performed to examine the protein expression levels of cell growth- and apoptosis-associated genes. The results demonstrated that MTDH was commonly expressed in CRC cell lines. MTDH silencing significantly suppressed cell growth, colony forming ability and migration while inducing the apoptosis of HCT116 cells. In addition, MTDH depletion induced S phase cell cycle arrest in HCT116 cells. Mechanistically, knockdown of MTDH markedly downregulated the expression of phosphorylated protein kinase B, c-Myc, proliferating cell nuclear antigen and B-cell lymphoma 2 (Bcl-2) protein in HCT116 cells, and the expression of p53 and Bcl-2-associated X protein was significantly increased compared with the negative control shRNA group (P<0.05), suggesting that MTDH may function through the expression of numerous types of apoptosis-associated and signaling channel proteins in CRC cells. Taken together, these data indicated that MTDH may serve as a biomarker and candidate therapeutic target for CRC.