Abstract 758: Long non-coding RNAH19 as a competing endogenous RNA of KIT in the progression of GIST

Abstract

Abstract Background: Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor with a wide range of biological behaviors, and activating mutations of KIT are particularly crucial to its development. Long non-coding RNAs (lncRNAs) have been identified as an oncogene in multiple cancer types, but data in GIST are missing. The aim of the study was to evaluate the contribution of lncRNA H19 to the malignant course of GISTs. Materials and Methods: RNA-seq analysis of lncRNA expression in five paired GIST and ANTs were analyzed to screen for differentially expressed lncRNAs. 274 human lncRNAs analyzed, exhibited significantly differential expressions with 186 genes being up-regulated and 88 genes being down-regulated compared to ANT (fold change>5, p<0.05). Unsupervised hierarchical clustering identified 48 lncRNAs and lncRNA H19 was the most overexpressed novel one. To assess the clinical importance of lncRNA H19 upregulation in GISTs, based on the expression levels 92 GIST patients were categorized into two groups: high (n=46) and low (n=46) lncRNA H19 expression. Results: After identifying lncRNA H19 as the most important one, validation in the expanded cohort confirmed the frequent upregulation of lncRNA H19 in GIST. Functional assays revealed that lncRNA H19 promotes GIST cell proliferation and metastasis. We could demonstrate that lncRNA H19 was predicted to sponge 19 miRNAs with six potential binding sites shared with KIT 3’-UTR using bio-informative database analysis. It was confirmed that lncRNA H19 was positively correlated with the expression of KIT, and the knockdown of lncRNA H19 led to the depression of KIT and its downstream pathway. Using luciferase reporter assays, lncRNA H19 was observed to sponge several miRNAs including miR-18a/b-5p, miR-19a/b-3p, miR-193a/b-3p, miR-216b-5p and mIR-3666. The combination of lncRNA H19 and KIT inhibition showed increased growth inhibition in GIST cell lines. Taken together, the data indicate that lncRNA H19 functions as a competing endogenous RNA (ceRNA) of KIT and promotes GIST progression. It could be shown that the expression levels of lncRNA H19 were significantly correlated with the progression markers of GIST, tumor size (P<0.001), mitosis count (P<0.001), and the modified NIH risk criteria (P<0.001) Conclusion: Our results indicate that lncRNA H19 can affect imatinib-induced apoptotic cell death and play a role in facilitating GIST progression by modulating the expression of KIT through the ceRNA network. High lncRNA H19 expression is associated with worse prognosis in patients with GIST and lncRNA H19 may serve as a new predictor of prognosis. Furthermore, targeting lncRNA H19/KIT ceRNA network appears to be a promising treatment for GIST. Citation Format: Peter Hohenberger, Lin Tu, Wenyi Zhao, Ming Wang Wang, Zizheng Zhang, Heike Allgayer, Hui Cao. Long non-coding RNAH19 as a competing endogenous RNA of KIT in the progression of GIST [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 758.