Search

Background and Objectives: RING finger protein 38 (RNF38) has been reported to be involved in the tumorigenesis of several tumors, but its role in colorectal cancer (CRC) is still not investigated. In the present study, we aimed to investigate the effect of RNF38 in CRC cells. Materials and Methods: The public tumor databases GEPIA and Kaplan-Meier Plotter were used to analyze RNF38 expression and patients' overall survival in CRC. The qRT-PCR was carried out to assess the mRNA levels of RNF38 and LDB1. Western blot and co-immunoprecipitation were used to detect protein expression and ubiquitination. CCK-8 assay was performed to analyze CRC cell growth and viability. Results: RNF38 was found downregulated in CRC tumor tissues and cell lines, and CRC patients with high RNF38 expression had a longer overall survival than patients with low RNF38 expression. Our further investigations showed that RNF38 interacted with LDB1, and downregulated LDB1 expression by inducing its polyubiquitination. Moreover, overexpression of RNF38 inhibited CRC cell growth but enforced LDB1 could significantly antagonize RNF38-induced cell growth inhibition in CRC cells. Additionally, RNF38/LDB1 axis was involved in the drug sensitivity of 5-FU to CRC cells. Conclusion: Our studies suggested that RNF38 was functional in CRC cells, and downregulated CRC cell growth by inducing LDB1 polyubiquitination, which indicated that RNF38 could be as a novel target for CRC therapy. [ABSTRACT FROM AUTHOR]

Background and objective: RNF6, an E3 ligase, has been reported to play an important role in the tumorigenesis in several tissues, but its role in gastric cancer is still unknown. In this study, we aimed to investigate the biological function and molecular mechanisms of RNF6 in gastric cancer.Materials and methods: The expression levels of RNF6 were detected by quantitative real-time PCR (qRT-PCR) and immunoblotting in gastric cancer tissues and cell lines. Cell Counting Kit-8 assay was performed to evaluate cell proliferation. Cell apoptosis was analyzed by flow cytometer and immunoblotting. Luciferase assay, immunoblotting and qRT-PCR were performed to explore the activation of STAT3. Immunoprecipitation was performed to evaluate the ubiquitination of SHP-1.Results: In this study, RNF6 was found to be upregulated in both primary tissues and cell lines of gastric cancer. Knockdown or overexpression of RNF6 inhibited or promoted cell growth of gastric cancer cells. Knockdown of RNF6 also induced the cleavage of PARP and promoted cell apoptosis in gastric cancer cells. In addition, knockdown of RNF6 also increased the cytotoxicity of doxorubicin against gastric cancer. Moreover, knockdown of RNF6 inhibited STAT3-derived luciferase activity and downregulated the phosphorylation of STAT3, but upregulated the protein level of SHP-1. Knockdown of RNF6 downregulated the expression of MCL1 and XIAP, which are target genes of STAT3. Further studies showed that RNF6 regulated the stability of SHP-1 by inducing its polyubiquitination.Conclusion: These results demonstrated that RNF6 was highly expressed in gastric cancer and regulated the growth of gastric cancer cells by affecting SHP-1/STAT3 signaling, which suggested that RNF6 could be a novel target for gastric cancer therapy. [ABSTRACT FROM AUTHOR]