Abstract 3116: MiR-215 is a tumor suppressor in colorectal cancer in vitro and in vivo

Abstract

Abstract Introduction: Colorectal cancer (CRC) is one of the most common types of cancers worldwide and it is the third leading cause of cancer-related death. Therefore, several efforts have been made to identify not only new diagnostic, prognostic and predictive biomarkers, but also therapeutic targets. One of the promising approaches is the characterization of the tumors using microRNAs (miRNAs). Patients and Methods: We have analyzed expression profiles of 667 miRNAs in 8 patients diagnosed for CRC and 8 paired adjacent non-tumoral tissues using TaqMan Low Density miRNA arrays. We have found miR-215 to be one of the most deregulated miRNAs, therefore its expression was further validated on independent cohort of 250 paired samples and correlated with clinicopathological features of the patients. Consequently, involvement of this miRNA in CRC pathogenesis was investigated using numerous in vitro and in vivo assays. Results: By use of miRNA expression profiling we have identified miR-215 to be highly down-regulated in tumor tissue of CRC patients (P < 0,0001). Subsequent validation on independent cohort of 250 paired samples of tumor tissues and adjacent non-tumor tissues confirmed this result, moreover, correlation between low expression of this miRNA and clinical stage (P < 0.0001) and lymph node metastasis (P < 0.0001) has been observed. In addition, significantly reduced levels of miR-215 have been detected in metastatic tissue (P < 0.0001) compared to primary tumor tissue and low expression of miR-215 was associated with shorter disease free survival (P = 0.0403). Subsequently, in vitro analyses have been performed using stable colorectal cancer cell lines in which the level of miR-215 was increased using transient or stable transfection. Higher levels of miR-215 lead to the cell cycle arrest in G1 phase of HCT-116+/+ cells (P = 0.01) and in G2/M phase of DLD-1 cells (P = 0.05), HCT-116-/- cells (P < 0.001) and HT-29 cells (P = 0.01), increased apoptosis of HCT-116+/+ cells (P < 0.001), reduced migration of DLD-1 cells (P < 0.001) and HCT-116+/+ cells (P < 0.001) and decreased proliferation activity of all analyzed cell lines (P < 0.001). Using qRT-PCR we have validated several predicted targets of miR-215 including XIAP, CD164, ALCAM or HOXB9. Finally, we have established human tumor xenografts in immunodeficient mice. We have observed that HCT-116+/+ transduced with vector containing precursor of miR-215 were associated with the slower growth of the tumors in vivo (N = 5; P = 0.04). Conclusions: The reduced expression of miR-215 has been observed in several cancers, therefore we presume that this miRNA functions as an important tumor suppressor. The results of our study indicate that miR-215 could serve as a new diagnostic and prognostic biomarker as well as potential therapeutic target for the treatment of CRC patients. The work has been supported by IGA MZCR NT13549-4/2012, NT13860-4/2012, NT13547-4/2012 and NT13514-4/2012. Citation Format: Petra Vychytilova-Faltejskova, Jana Merhautova, Jitka Mlcochova, Lenka Radova, Robert Iliev, Marek Svoboda, Rostislav Vyzula, Ondrej Slaby. MiR-215 is a tumor suppressor in colorectal cancer in vitro and in vivo. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3116. doi:10.1158/1538-7445.AM2015-3116