BioProject

Purpose: Preoperative 5-fluorouracil (5-FU) based radiochemotherapy (RCT) represents the standard treatment for locally advanced rectal cancer. Both, tumor response and progression vary considerably. MicroRNAs represent master regulators of gene expression, and may therefore contribute to this heterogeneity. Results: Thirty-six miRNAs were identified to significantly correlate with sensitivity of CRC cell lines to RCT (q < 0.05). This list included miR320a as most significantly correlated as well as other miRNAs involved in the MAPK-, TGF- and Wnt-pathway. Importantly, transfection of selected miRNAs (let7g, miR-132, miR-224, miR-320a and miR-429) each induced a shift of sensitivity (p<0.00001). Moreover, high expression of miR-224 was associated with a poor prognosis in rectal cancer patients (p=0.043). Overall design: Experimental design: Genome-wide microRNA (miRNA) profiling was performed from 12 colorectal cancer (CRC) cell lines. To establish an in vitro signature of radiochemosensitivity, these profiles were correlated to the individual sensitivities of each cell line to 5-FU and radiation. The functional relevance of selected miRNAs was validated by transfecting miRNA-mimics into SW480 cells, followed by treatment with 5-FU and radiation. 12 Samples with 3 replicates each.