Haojie Jin1, Cun Wang1, Guangzhi Jin2, Haoyu Ruan1, Dishui Gu3, Lin Wei1, Hui Wang1, Ning Wang1, Einthavy Arunachalam4, Yurong Zhang1, Xuan Deng1, Chen Yang1, Yi Xiong5, Hugang Feng6, Ming Yao1, Jingyuan Fang1, Jianren Gu1, Wenming Cong7, Wenxin Qin8. 1. State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China. 2. Department of Pathology, Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai, China. 3. State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Department of Pathophysiology, School of Basic Medical Sciences, Guangdong Medical University, Dongguan, Guangdong, China. 4. State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; The School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surry, UK. 5. State Key Laboratory of Microbial Metabolism and College of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai, China. 6. Department of Life Science, Imperial College, London, UK. 7. Department of Pathology, Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai, China. Electronic address: wmcong@smmu.edu.cn. 8. State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China. Electronic address: wxqin@sjtu.edu.cn.
Abstract
BACKGROUND & AIMS: Individuals with Down syndrome have a low risk for many solid tumors, prompting the search for tumor suppressor genes on human chromosome 21 (HSA21). We aimed to identify and explore potential mechanisms of tumor suppressors on HSA21 in hepatocellular carcinoma (HCC). METHODS: We compared expression of HSA21 genes in 14 pairs of primary HCC and adjacent noncancer liver tissues using the Affymetrix HG-U133 Plus 2.0 array (Affymetrix, Santa Clara, CA). HCC tissues and adjacent normal liver tissues were collected from 108 patients at a hospital in China for real-time polymerase chain reaction and immunohistochemical analyses; expression levels of regulator of calcineurin 1 (RCAN1) isoform 4 (RCAN1.4) were associated with clinical features. We overexpressed RCAN1.4 from lentiviral vectors in MHCC97H and HCCLM3 cells and knocked expression down using small interfering RNAs in SMMC7721 and Huh7 cells. Cells were analyzed in proliferation, migration, and invasion assays. HCC cells that overexpressed RCAN1.4 or with RCAN1.4 knockdown were injected into livers or tail veins of nude mice; tumor growth and numbers of lung metastases were quantified. We performed bisulfite pyrosequencing and methylation-specific polymerase chain reaction analyses to analyze CpG island methylation. We measured phosphatase activity of calcineurin in HCC cells. RESULTS: RCAN1.4 mRNA and protein levels were significantly decreased in primary HCC compared with adjacent noncancer liver tissues. Reduced levels of RCAN1.4 mRNA were significantly associated with advanced tumor stages, poor differentiation, larger tumor size, and vascular invasion. Kaplan-Meier survival analysis showed that patients with HCCs with lower levels of RCAN1.4 mRNA had shorter time of overall survival and time to recurrence than patients whose tumors had high levels of RCAN1.4 mRNA. In HCC cell lines, expression of RCAN1.4 significantly reduced proliferation, migration, and invasive activity. HCC cells that overexpressed RCAN1.4 formed smaller xenograft tumors, with fewer metastases and blood vessels, than control HCC cells. In HCC cells, RCAN1.4 inhibited expression of insulin-like growth factor 1 and vascular endothelial growth factor A by reducing calcineurin activity and blocking nuclear translocation of nuclear factor of activated T cells (NFAT1). HCC cells incubated with the calcineurin inhibitor cyclosporin A had decreased nuclear level of NFAT1. HCC cells had hypermethylation of a CpG island in the 5' regulatory region of RCAN1.4, which reduced its expression. CONCLUSIONS: RCAN1.4 is down-regulated in HCC tissues, compared with non-tumor liver tissues. RCAN1.4 prevents cell proliferation, migration, and invasion in vitro; overexpressed RCAN1.4 in HCC cells prevents growth, angiogenesis, and metastases of xenograft tumors by inhibiting calcineurin activity and nuclear translocation of NFAT1.
BACKGROUND & AIMS: Individuals with Down syndrome have a low risk for many solid tumors, prompting the search for tumor suppressor genes on human chromosome 21 (HSA21). We aimed to identify and explore potential mechanisms of tumor suppressors on HSA21 in hepatocellular carcinoma (HCC). METHODS: We compared expression of HSA21 genes in 14 pairs of primary HCC and adjacent noncancer liver tissues using the Affymetrix HG-U133 Plus 2.0 array (Affymetrix, Santa Clara, CA). HCC tissues and adjacent normal liver tissues were collected from 108 patients at a hospital in China for real-time polymerase chain reaction and immunohistochemical analyses; expression levels of regulator of calcineurin 1 (RCAN1) isoform 4 (RCAN1.4) were associated with clinical features. We overexpressed RCAN1.4 from lentiviral vectors in MHCC97H and HCCLM3 cells and knocked expression down using small interfering RNAs in SMMC7721 and Huh7 cells. Cells were analyzed in proliferation, migration, and invasion assays. HCC cells that overexpressed RCAN1.4 or with RCAN1.4 knockdown were injected into livers or tail veins of nude mice; tumor growth and numbers of lung metastases were quantified. We performed bisulfite pyrosequencing and methylation-specific polymerase chain reaction analyses to analyze CpG island methylation. We measured phosphatase activity of calcineurin in HCC cells. RESULTS:RCAN1.4 mRNA and protein levels were significantly decreased in primary HCC compared with adjacent noncancer liver tissues. Reduced levels of RCAN1.4 mRNA were significantly associated with advanced tumor stages, poor differentiation, larger tumor size, and vascular invasion. Kaplan-Meier survival analysis showed that patients with HCCs with lower levels of RCAN1.4 mRNA had shorter time of overall survival and time to recurrence than patients whose tumors had high levels of RCAN1.4 mRNA. In HCC cell lines, expression of RCAN1.4 significantly reduced proliferation, migration, and invasive activity. HCC cells that overexpressed RCAN1.4 formed smaller xenograft tumors, with fewer metastases and blood vessels, than control HCC cells. In HCC cells, RCAN1.4 inhibited expression of insulin-like growth factor 1 and vascular endothelial growth factor A by reducing calcineurin activity and blocking nuclear translocation of nuclear factor of activated T cells (NFAT1). HCC cells incubated with the calcineurin inhibitor cyclosporin A had decreased nuclear level of NFAT1. HCC cells had hypermethylation of a CpG island in the 5' regulatory region of RCAN1.4, which reduced its expression. CONCLUSIONS:RCAN1.4 is down-regulated in HCC tissues, compared with non-tumor liver tissues. RCAN1.4 prevents cell proliferation, migration, and invasion in vitro; overexpressed RCAN1.4 in HCC cells prevents growth, angiogenesis, and metastases of xenograft tumors by inhibiting calcineurin activity and nuclear translocation of NFAT1.