Prognostic role of microRNA-34a expression in colorectal cancer.

472 Background: Colorectal Cancer (CRC) is one of the leading causes of death worldwide. MicroRNA-34a (miR-34a), a tumor suppressor gene, is known to be down-regulated in CRC cell lines and recently shown to be a cell-fate determinant in early-stage dividing colon cancer stem cells. However, its prognostic significance is unclear. Methods: MiR-34a detection was performed by in situ hybridization on a CRC tissue microarray (n=127; stage I, 21 patients; II: 42; III: 33; IV: 31). Its expression was graded as negative (no signal), low (expression in 1-19% of cancer cells), moderate (20-49% of cancer cells), and strong (50-100% of cancer cells). The correlations between miR-34a expression and EGFR, osteopontin (OPN), p53, Ki67, LEF1, VEGF, COX2, MMR, stage and grade were evaluated by chi-squared test and Spearman's rank correlation coefficient. Kaplan-Meier survival analysis, log-rank test and Cox regression model were used to assess the association of miR-34a expression with recurrence-free survival (RFS) and...