Fangfang Duan1, Hao Wu1, Dongwei Jia1, Weicheng Wu1, Shifang Ren1, Lan Wang1, Shushu Song1, Xinying Guo1, Fenglin Liu2, Yuanyuan Ruan3, Jianxin Gu4. 1. Key Laboratory of Glycoconjugate Research Ministry of Health, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China; Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China. 2. Department of General Surgery, Zhongshan Hospital, Fudan University, Shanghai 200032, China. Electronic address: liu.fenglin@zs-hospital.sh.cn. 3. Key Laboratory of Glycoconjugate Research Ministry of Health, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China; Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China. Electronic address: yuanyuanruan@fudan.edu.cn. 4. Key Laboratory of Glycoconjugate Research Ministry of Health, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China; Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China; Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China.
Abstract
BACKGROUND & AIMS: Aberrant oncogenic mRNA translation and protein O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) are general features during tumorigenesis. Nevertheless, whether and how these two pathways are interlinked remain unknown. Our previous study indicated that ribosomal receptor for activated C-kinase 1 (RACK1) promoted chemoresistance and growth in hepatocellular carcinoma (HCC). The aim of this study is to examine the role of RACK1 O-GlcNAcylation in oncogene translation and HCC carcinogenesis. METHODS: The site(s) of RACK1 for O-GlcNAcylation was mapped by mass spectrometry analysis. HCC cell lines were employed to examine the effects of RACK1 O-GlcNAcylation on the translation of oncogenic factors and behaviors of tumor cells in vitro. Transgenic knock-in mice were used to detect the role of RACK1 O-GlcNAcylation in modulating HCC tumorigenesis in vivo. The correlation of RACK1 O-GlcNAcylation with tumor progression and relapse were analyzed in clinical HCC samples. RESULTS: We found that ribosomal RACK1 was highly modified by O-GlcNAc at Ser122. O-GlcNAcylation of RACK1 enhanced its protein stability, ribosome binding and interaction with PKCβII (PRKCB), leading to increased eukaryotic translation initiation factor 4E phosphorylation and translation of potent oncogenes in HCC cells. Genetic ablation of RACK1 O-GlcNAcylation at Ser122 dramatically suppressed tumorigenesis, angiogenesis, and metastasis in vitro and in diethylnitrosamine (DEN)-induced HCC mouse model. Increased RACK1 O-GlcNAcylation was also observed in HCC patient samples and correlated with tumor development and recurrence after chemotherapy. CONCLUSIONS: These findings demonstrate that RACK1 acts as key mediator linking O-GlcNAc metabolism to cap-dependent translation during HCC tumorigenesis. Targeting RACK1 O-GlcNAcylation provides promising options for HCC treatment. LAY SUMMARY: O-GlcNAcylation of ribosomal receptor for activated C-kinase 1 at the amino acid serine122 promotes its stability, ribosome localization and interaction with the protein kinase, PKCβII, thus driving the translation of oncogenes and tumorigenesis of hepatocellular carcinoma. Increased O-GlcNAcylation of ribosomal receptor for activated C-kinase 1 is positively correlated with tumor growth, metastasis and recurrence in patients with hepatocellular carcinoma.
BACKGROUND & AIMS: Aberrant oncogenic mRNA translation and protein O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) are general features during tumorigenesis. Nevertheless, whether and how these two pathways are interlinked remain unknown. Our previous study indicated that ribosomal receptor for activated C-kinase 1 (RACK1) promoted chemoresistance and growth in hepatocellular carcinoma (HCC). The aim of this study is to examine the role of RACK1 O-GlcNAcylation in oncogene translation and HCC carcinogenesis. METHODS: The site(s) of RACK1 for O-GlcNAcylation was mapped by mass spectrometry analysis. HCC cell lines were employed to examine the effects of RACK1 O-GlcNAcylation on the translation of oncogenic factors and behaviors of tumor cells in vitro. Transgenic knock-in mice were used to detect the role of RACK1 O-GlcNAcylation in modulating HCC tumorigenesis in vivo. The correlation of RACK1 O-GlcNAcylation with tumor progression and relapse were analyzed in clinical HCC samples. RESULTS: We found that ribosomal RACK1 was highly modified by O-GlcNAc at Ser122. O-GlcNAcylation of RACK1 enhanced its protein stability, ribosome binding and interaction with PKCβII (PRKCB), leading to increased eukaryotic translation initiation factor 4E phosphorylation and translation of potent oncogenes in HCC cells. Genetic ablation of RACK1 O-GlcNAcylation at Ser122 dramatically suppressed tumorigenesis, angiogenesis, and metastasis in vitro and in diethylnitrosamine (DEN)-induced HCC mouse model. Increased RACK1 O-GlcNAcylation was also observed in HCC patient samples and correlated with tumor development and recurrence after chemotherapy. CONCLUSIONS: These findings demonstrate that RACK1 acts as key mediator linking O-GlcNAc metabolism to cap-dependent translation during HCC tumorigenesis. Targeting RACK1 O-GlcNAcylation provides promising options for HCC treatment. LAY SUMMARY: O-GlcNAcylation of ribosomal receptor for activated C-kinase 1 at the amino acid serine122 promotes its stability, ribosome localization and interaction with the protein kinase, PKCβII, thus driving the translation of oncogenes and tumorigenesis of hepatocellular carcinoma. Increased O-GlcNAcylation of ribosomal receptor for activated C-kinase 1 is positively correlated with tumor growth, metastasis and recurrence in patients with hepatocellular carcinoma.