Attenuated RND1 Expression Confers Malignant Phenotype and Predicts Poor Prognosis in Hepatocellular Carcinoma
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The RND1 gene encodes a protein that belongs to the Rho GTPase family, which regulates various cellular functions. Depletion of RND1 expression activates the oncogenic Ras signaling pathway. In this study, we aimed to clarify the clinical significance of RND1 expression in predicting prognosis and to investigate its biological role in human hepatocellular carcinoma (HCC).
The association between RND1 expression and clinical outcomes in patients with HCC was analyzed in three independent cohorts: 120 cases resected in our hospital; 370 cases in The Cancer Genome Atlas (TCGA); and 242 cases in GSE14520. Gene set enrichment analysis (GSEA) was also conducted. Finally, knockdown experiments were performed using small interfering RNA (siRNA) in vitro.
In all cohorts, RND1 expression was decreased as cancer progressed, and was affected by promoter methylation. In our HCC cases, the 5-year overall survival (OS) and recurrence-free survival of patients with low RND1 expression was significantly poorer than those of patients with high RND1 expression. TCGA and GSE14520 analyses provided similar results for OS. Multivariate analysis indicated that RND1 expression was an independent prognostic factor for OS in all three cohorts. Additionally, GSEA showed an inverse correlation between RND1 expression and the Ras signaling activity. In vitro, knockdown of RND1 expression resulted in significant increases in proliferation, invasion, and chemoresistance to cisplatin in HCC cells.
Reduced RND1 expression in HCC was associated with cancer progression, likely through regulation of the Ras signaling pathway, and may serve as a novel clinical biomarker for predicting prognosis in patients with HCC.
KeywordsOverall Survival Gene Promoter Methylation Electronic Supplementary Table GSE14520 Dataset Biotechnology Information Gene Expression Omnibus
This research used the supercomputing resource provided by the Human Genome Center at the Institute of Medical Science, University of Tokyo (http://sc.hgc.jp/shirokane.html). HCC clinical samples were provided by the Oita Red Cross Hospital, Hiroshima Red Cross Hospital, Atomic-bomb Survivors Hospital, and Iizuka Hospital.
Hisateru Komatsu, Tomohiro Iguchi, Takaaki Masuda, Hidenari Hirata, Masami Ueda, Shinya Kidogami, Yushi Ogawa, Kuniaki Sato, Qingjiang Hu, Sho Nambara, Tomoko Saito, Shotaro Sakimura, Ryutaro Uchi, Shuhei Ito, Hidetoshi Eguchi, Keishi Sugimachi, Hidetoshi Eguchi, Yuichiro Doki, Masaki Mori, and Koshi Mimori have no conflicts of interest to disclose.
This work was supported in part by the following grants and foundations: Japan Society for the Promotion of Science Grant-in-Aid for Scientific Research (grant numbers 24592005 and 15K10168) and the OITA Cancer Research Foundation.