Characterization of oncogenic function of microRNA665 in esophageal squamous cell carcinoma

Abstract

Background: Esophageal squamous cell carcinoma (ESCC) has been increasing in incidence, but knowledge of the genetic basis of this disease remains limited. In general, esophageal carcinoma can be divided into two main types: Esophageal Squamous Cell Carcinoma (ESCC) and Esophageal Adenocarcinoma (EAC). The pathogenesis of esophageal carcinoma still remains unclear, although some risk factors like chronic irritation, or chronic inflammation which may be caused by diseases such as gastroesophageal reflux disease (GERD) or unhealthy lifestyles like smoking have been proved to be related to the carcinogenic process. Diagnosis and treatment for this kind of cancer have continue to develop and evolve, but the 5-year overall survival rate is still relatively low. Therefore, it is clinically important to identify any potential genetic changes which may help us to discover some useful biomarker targets for the further development of more direct and harmless targeted therapy for our esophageal cancer patients. Objectives: In this study, I aimed to identify some potential oncogenic microRNA (miRNA) and to study their clinical meaning in ESCC patients. Methods: Microarray was applied to identify differentially expressed miRNAs in ESCC tumour tissue, compared with corresponding adjacent non-tumour esophageal tissue. One candidate oncogenic miRNA, miR-665, was investigated in the present study. After testing the expression level of miR-665 in ESCC cell lines and patients’ samples with RT-PCR, miR-665 stably expressing cells was established using two ESCC cell lines (KYSE30 and KYSE510). Functional characterization was then conducted using in vitro and in vivo assays to examine the effect of miR-665 towards the development of ESCC. Bioinformatic software such as Target Scan was used to generate a list of predicted target genes that may be modulated by miR-665. Results: The high expression of miR-665 has been confirmed in ESCC tissues and cell lines, showing the potential carcinogenic function of miR-665. Ectopic expression of miR-665 also demonstrates its ability to enhance tumour growth and invasion in vitro and in vivo. Bioinformatic analysis of miR-665 predicted targets showed putative binding sites for miR-665 within the 3’UTR region of NLK. Conclusions: This study has identified a novel miRNA and a related gene which might play an important role in the pathogenesis of ESCC, affecting the cancer process and tumour growth. This may help to find potential new biomarker for the future improvement and development of new treatment of ESCC patients.