Dataset Information

CACYBP Enhances Cytoplasmic Retention of P27^Kip1 to Promote Hepatocellular Carcinoma Progression in the Absence of RNF41 Mediated Degradation.

ABSTRACT: Calcyclin-binding protein (CACYBP) is a multi-ligand protein implicated in the progression of various human cancers. However, its function in hepatocellular carcinoma (HCC) remains unknown. Methods: The expression of CACYBP and RNF41 (RING finger protein 41) in HCC cancer and adjacent non-tumor tissues was detected by immunohistochemistry. CCK-8 assays, colony formation assays, flow cytometry detection and xenograft models were used to evaluate the impact of CACYBP expression on HCC cell growth, apoptosis and cell cycle regulation. Immunoprecipitation and ubiquitination assays were performed to determine how RNF41 regulates CACYBP. The regulatory mechanism of RNF41-CACYBP signaling axis on P27^Kip1 was investigated by western blotting and immunofluorescence. Results: CACYBP was highly expressed and associated with poor prognosis in HCC. CACYBP expression was required for HCC cell growth in vitro and in vivo. Moreover, we identified RNF41 as a specific binding partner of CACYBP at exogenous and endogenous levels. RNF41 recruited CACYBP by its C-terminal substrate binding domain, subsequently ubiquitinating CACYBP and promoting its degradation in both proteasome- and lysosome-dependent pathways. In HCC tissues, RNF41 expression was reduced and conferred a negative correlation with CACYBP expression. Mechanistically, CACYBP overexpression stimulated the Ser10, Thr157 and Thr198 phosphorylation of P27^Kip1 and its cytoplasmic retention, and RNF41 co-expression attenuated this phenomenon. CACYBP depletion led to decreased levels of cyclin D1, cyclin A2, CDK2 and CDK4, causing a typical cell cycle arrest at G1/S phase and increasing apoptosis in HCC cells. P27^Kip1-S10D but not P27^Kip1-S10A reconstitution rescued partially the cell cycle function and apoptotic feature after CACYBP depletion. Conclusion: Our findings provide novel insights into the functional role and regulatory mechanism of CACYBP in HCC.

SUBMITTER: Lian YF

PROVIDER: S-EPMC6857042 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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CACYBP Enhances Cytoplasmic Retention of P27<sup>Kip1</sup> to Promote Hepatocellular Carcinoma Progression in the Absence of RNF41 Mediated Degradation.

Lian Yi-Fan YF Huang Yan-Lin YL Zhang Yao-Jun YJ Chen Dong-Mei DM Wang Jia-Liang JL Wei Huan H Bi Yan-Hua YH Jiang Zhi-Wu ZW Li Peng P Chen Min-Shan MS Huang Yue-Hua YH

Theranostics 20191022 26

Calcyclin-binding protein (CACYBP) is a multi-ligand protein implicated in the progression of various human cancers. However, its function in hepatocellular carcinoma (HCC) remains unknown. <b>Methods</b>: The expression of CACYBP and RNF41 (RING finger protein 41) in HCC cancer and adjacent non-tumor tissues was detected by immunohistochemistry. CCK-8 assays, colony formation assays, flow cytometry detection and xenograft models were used to evaluate the impact of CACYBP expression on HCC cell ...[more]

PMID: 31754404

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Project description:BackgroundPoly C Binding Protein 1 (PCBP1) is an RNA-binding protein that binds and regulates translational activity of subsets of cellular mRNAs. Depletion of PCBP1 is implicated in various carcinomas, but the underlying mechanism in tumorigenesis remains elusive.MethodsWe performed a transcriptome-wide screen to identify novel bounding mRNA of PCBP1. The bind regions between PCBP1 with target mRNA were investigated by using point mutation and luciferase assay. Cell proliferation, cell cycle, tumorigenesis and cell apoptosis were also evaluated in ovary and colon cancer cell lines. The mechanism that PCBP1 affects p27 was analyzed by mRNA stability and ribosome profiling assays. We analyzed PCBP1 and p27 expression in ovary, colon and renal tumor samples and adjacent non-tumor tissues using RT-PCR, Western Blotting and immunohistochemistry. The prognostic significance of PCBP1 and p27 also analyzed using online databases.ResultsWe identified cell cycle inhibitor p27Kip1 (p27) as a novel PCBP1-bound transcript. We then demonstrated that binding of PCBP1 to p27 3'UTR via its KH1 domain mainly stabilizes p27 mRNA, while enhances its translation to fuel p27 expression, prior to p27 protein degradation. The upregulated p27 consequently inhibits cell proliferation, cell cycle progression and tumorigenesis, whereas promotes cell apoptosis under paclitaxel treatment. Conversely, knockdown of PCBP1 in turn compromises p27 mRNA stability, leading to lower p27 level and tumorigenesis in vivo. Moreover, forced depletion of p27 counteracts the tumor suppressive ability of PCBP1 in the same PCBP1 over-expressing cells. Physiologically, we showed that decreases of both p27 mRNA and its protein expressions are well correlated to PCBP1 depletion in ovary, colon and renal tumor samples, independent of the p27 ubiquitin ligase Skp2 level. Correlation of PCBP1 with p27 is also found in the tamoxifen, doxorubincin and lapatinib resistant breast cancer cells of GEO database.ConclusionOur results thereby indicate that loss of PCBP1 expression firstly attenuates p27 expression at post-transcriptional level, and subsequently promotes carcinogenesis. PCBP1 could be used as a diagnostic marker to cancer patients.

Dataset Information

CACYBP Enhances Cytoplasmic Retention of P27^Kip1 to Promote Hepatocellular Carcinoma Progression in the Absence of RNF41 Mediated Degradation.

Publications

CACYBP Enhances Cytoplasmic Retention of P27<sup>Kip1</sup> to Promote Hepatocellular Carcinoma Progression in the Absence of RNF41 Mediated Degradation.

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Dataset Information

CACYBP Enhances Cytoplasmic Retention of P27Kip1 to Promote Hepatocellular Carcinoma Progression in the Absence of RNF41 Mediated Degradation.

Publications

CACYBP Enhances Cytoplasmic Retention of P27<sup>Kip1</sup> to Promote Hepatocellular Carcinoma Progression in the Absence of RNF41 Mediated Degradation.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

CACYBP Enhances Cytoplasmic Retention of P27^Kip1 to Promote Hepatocellular Carcinoma Progression in the Absence of RNF41 Mediated Degradation.