Using deep sequencing of formalin-fixed paraffin embedded (FFPE) rectal cancer biopsy tissue to analyze miRNA expression in patients with rectal cancer.

487 Background: miRNAs have been shown to be involved in tumor initiation, progression and metastasis in many cancers including colorectal cancer. However, miRNA profiling specifically in rectal cancer is not well characterized. Our objective was to generate a miRNA expression profile in locally advanced rectal cancer using formalin fixed paraffin embedded (FFPE) biopsy tissue collected from patients with locally advanced rectal cancer. Methods: We collected pre-treatment biopsy tissue and matched normal tissue from 40 rectal cancer patients treated with pre-operative chemoradiation (CRT) and total mesorectal excision (TME). We extracted 50-1000ng of total RNA from FFPE biopsies and optimized small RNA sample preparation for deep-sequencing. We then performed deep sequencing on biopsy and matched normal tissue and compared miRNA expression in biopsy and normal tissues using paired T-test and multiple testing (Q-bound <0.05) to determine significant miRNA expression changes in rectal cancer. Results: 182 m...