Abstract 506: miR-203a-3p may play a tumor suppressor role in esophageal cancer by targeting GATA Binding Protein 6

Abstract

Abstract Esophageal cancer (EC) is the eighth most common cancer and the sixth most common cause of cancer death worldwide. MicroRNAs (miRNAs) are small 19-22nt non-coding single-strand RNAs that regulate diverse cellular processes and are dysregulated in a variety of cancers including EC. Using bioinformatics analysis, we identified a list of dysregulated miRNAs from most recent studies on miRNA expression profiling in EC, including miR-203a-3p, which was reported as a tumor suppressor miRNA and dysregulated in many malignancies. GATA Binding Protein 6 (GATA6) is a member of zinc finger transcription factors that is amplified or overexpressed in many tumors, such as breast cancer, pancreatic cancer, esophageal cancer, etc. Our bioinformatics analysis showed that GATA6 is a potential target of miR-203a-3p. Therefore, we hypothesize that miR-203a-3p functions as a tumor suppressor miRNA in esophageal cancer by targeting GATA6. Four esophageal cancer cell lines, including esophageal squamous cell carcinoma (ESCC) cell lines (KYSE70, KYSE180) and adenocarcinoma (EAC) cell lines (JHU-ad1,FLO-1), along with one normal esophageal cell line (HET-1A) were cultured. Six of ESCC FFPE samples were obtained and microdissected into normal, dysplasia and cancer tissues. The expression levels of miR-203a-3p and GATA6 were determined by TaqMan and CYBR green qRT-PCR assays, respectively from the cell lines and patient tissues after total RNA isolation by the Trizol reagent. The miR-203a-3p inhibitor or mimic was transfected to the above cell lines by the Lipofectamine® RNAiMAX reagent. MTT assays were used to determine the cell proliferation. The t-test was used for statistical analysis. After successful transfection of miR-203a-3p mimic, we found that cell proliferation was decreased accompanied by significantly lower GATA6 expression compared to the mock groups (p<0.05) in four cell lines (KYSE70, Het-1A, JHU-ad1 and FLO-1). However, when cells were transfected with miR-203a-3p inhibitor in KYSE70, KYSE180, JHU-ad1 and FLO-1, cell proliferation rate and GATA6 expression were both increased compared to the inhibitor mock controls (p<0.05). In clinical samples, we found that miR-203a-3p expression was downregulated during the progression of EC (100%). To determine the specificity of the functional relationship between miR-203a-3p and GATA6 in EC, we performed the luciferase array, invasion assay and other functional assays, and in the process of obtaining more clinical samples to determine if miR-203a-3p functions differently in ESCC and EAC. Our data has shown an inverse correlation between miR-203a-3p and GATA6 expression in EC, which, along with our bioinformatics analysis, indicates that miR-203a-3p downregulates GATA6 expression by directly targeting its 3'-UTR in EC. Therefore, miR-203a-3p, as a tumor suppressor, may be involved in EC development, and it may serve as a novel marker for EC management. Citation Format: Caiqiao Yin, Xiaohui Tan, Qingfeng Tan, Jingjing Wang, Jiqiao Zhang, Xiaoling Wu, Tao Chen, Hongmei Jiao, Sidney W. Fu. miR-203a-3p may play a tumor suppressor role in esophageal cancer by targeting GATA Binding Protein 6 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 506.