G3BP2 regulated by the lncRNA LINC01554 facilitates esophageal squamous cell carcinoma metastasis through stabilizing HDGF transcript

Oncogene ARTICLE www.nature.com/onc OPEN G3BP2 regulated by the lncRNA LINC01554 facilitates esophageal squamous cell carcinoma metastasis through stabilizing HDGF transcript Yinli Zheng1,2,8, Jinjun Wu3,8, Ru Deng1,2,8, Censhan Lin1,2,8, Yuhua Huang1,2, Xia Yang1,2, Chunhua Wang 1,2, Mingming Yang1,2, ✉ ✉ Yangfan He1,2, Jiabin Lu1,2, Xiaodong Su1,4, Qian Yan5, Yinghui Zhu 1, Xinyuan Guan 1,6,7, Yan Li 1 and Jingping Yun 1,2 © The Author(s) 2021 1234567890();,: Metastasis is the leading cause of death of patients with esophageal squamous cell carcinoma (ESCC). Although an increasing number of studies have demonstrated the involvement of G3BP2 in several human cancers, how G3BP2 interacts with long noncoding RNAs and regulates mRNA transcripts in mediating ESCC metastasis remains unclear. In this study, we uncovered that G3BP2 was upregulated in ESCC. Further analysis revealed that upregulation of G3BP2 was significantly correlated with lymph node metastasis, depth of tumor invasion and unfavorable outcomes in ESCC patients. Both in vitro and in vivo functional assays demonstrated that G3BP2 dramatically enhanced ESCC cell migration and invasion. Mechanistically, LINC01554 maintained the high G3BP2 expression in ESCC by protecting G3BP2 from degradation through ubiquitination and the interaction domains within LINC01554 and G3BP2 were identified. In addition, RNA-seq revealed that HDGF was regulated by G3BP2. G3BP2 bound to HDGF mRNA transcript to stabilize its expression. Ectopic expression of HDGF effectively abolished the G3BP2 depletion-mediated inhibitory effect on tumor cell migration. Intriguingly, introduction of compound C108 which can inhibit G3BP2 remarkedly suppressed ESCC cell metastasis in vitro and in vivo. Collectively, this study describes a newly discovered regulatory axis, LINC01554/G3BP2/HDGF, that facilitates ESCC metastasis and will provide novel therapeutic strategies for ESCC. Oncogene; https://doi.org/10.1038/s41388-021-02073-0 INTRODUCTION Esophageal carcinoma (EC) is an exceedingly aggressive cancer with a high mortality rate and poor prognosis worldwide [1], and squamous cell carcinoma is the major pathological type of EC [2]. Clinically, metastasis is the ultimate challenge for effectively treating ESCC. The lymph nodes and lung are the most frequent metastatic organs. To date, although several whole-exon sequencing studies have identified universally mutated genes that illustrate the genetic alterations in patients with ESCC [3–5] and lots of research on ESCC metastasis have been carried out [6, 7], the precise molecular mechanisms and complexity of ESCC metastasis are still not fully understood. Thus, discovering the mechanisms of the dissemination ESCC cells will be valuable for the development of novel therapeutic approaches for ESCC. Ras-GTPase-activating protein (SH3 domain)-binding protein 2 (G3BP2) is located on the long arm of chromosome 4 (4q21), which has been reported to harbor genetic variant risk factors for ESCC in the Chinese population [8]. G3BP2 is mainly distributed in the cytoplasm and participates in the formation of stress granules 1 [9], cell differentiation, proliferation, and signal transduction [10]. Accumulating evidence has demonstrated that aberrant expression of G3BP2 contributes to cancer initiation and progression, such as high expression of G3BP2 increasing cell stemness, metastasis and chemoresistance in breast cancer [11–13], upregulation of G3BP2 promoting cell growth and survival in prostate cancer [14], and bladder cancer [15]. In addition, G3BP2 attenuates the effectiveness of radiation in the treatment of oral cancer [16]. However, the function and mechanism of G3BP2 in ESCC metastasis have yet to be elucidated. G3BP2 belongs to the G3BP protein family, which has four distinct motifs in its protein structure, including a nuclear transport factor 2-like domain, acidic and proline-rich regions, an RNA recognition motif (RRM) and an arginine and glycine rich box (RGG box). Among the motifs, the RRM domain is the most common specific basic domain of RNA binding proteins (RBPs) [17]. Mounting evidence has revealed that RBPs engage in posttranscriptional regulation by modulating RNA splicing, polyadenylation, mRNA stability, mRNA localization, and translation through interacting with coding or Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, P. R. China. Department of Pathology, Sun Yat-sen University Cancer Center, Guangzhou 510060, PR China. 3Joint Laboratory for Translational Cancer Research of Chinese Medicine of the Ministry of Education of the People’s Republic of China, International Institute for Translational Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou 510006, PR China. 4Department of Thoracic Surgery, Sun Yat-sen University Cancer Center, Guangzhou 510060, PR China. 5Department of Colorectal Surgery, Guangdong Institute of Gastroenterology, Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou 510000, PR China. 6Department of Clinical Oncology, State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong 852, PR China. 7Department of Clinical Oncology, The University of Hong Kong-Shenzhen Hospital, Shenzhen 518053, PR China. 8These authors contributed equally: Yinli Zheng, Jinjun Wu, Ru Deng, Censhan Lin. ✉email: ; 2 Y. Zheng et al. 2 Fig. 1 Upregulation of G3BP2 is correlated with unfavorable outcome in ESCC patients. A Big data mining from Oncomine (https://www. oncomine.org) and TCGA (https://www.cancer.gov) showed that G3BP2 was upregulated in ESCC. B mRNA expression of G3BP2 was examined by RT-qPCR using SYSUCC samples. GAPDH served as an internal control. C The protein expression of G3BP2 in immortalized esophageal epithelium cells (NE1) and ESCC cell lines. GAPDH acted as a loading control. D Representative images of G3BP2 staining in nontumor tissue and ESCC tissue microarray by immunohistochemistry analysis. Scale bar, up: 100 μm, down: 50 μm. E IHC score of G3BP2 staining in ESCCs and corresponding nontumor samples (n = 93). F and G Clinicopathologic correlation analyses of G3BP2 expression in ESCC. H Correlation between G3BP2 expression and overall survival was analyzed in the SYSUCC cohort by Kaplan-Meier curve analysis. noncoding RNAs [18]. Therefore, RBPs are critical for maintaining the homeostasis of gene expression. Abnormal expression of RBPs disrupts gene expression homeostasis and causes human diseases, especially cancers. As RBPs, G3BPs have been reported to participate in the regulation of gene expression by modulating mRNA stability and translation under the stimulation of environmental stresses in several diseases, including cancer progression and virus survival [10]. Nevertheless, how G3BP2 interacts with mRNAs in ESCC remain (...truncated)