SPOP-PTEN-SUFU axis promotes progression of clear cell renal cell carcinoma via activating SHH and WNT pathway.
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ABSTRACT: Although E3 ligase Speckle type BTB/POZ protein (SPOP) promotes tumorigenesis by acting as a key regulatory hub in clear cell renal cell carcinoma (ccRCC), the detailed molecular mechanism remains unclear. Here, we demonstrate that a well-known tumor suppressor, Suppressor of Fused (SUFU), is downregulated by SPOP. Interestingly, this downregulation depends on cullin-3(Cul3)-SPOP E3 ligase, but SUFU is not a direct substrate of SPOP. Phosphatase and tensin homolog (PTEN), a ubiquitinated substrate of SPOP, is involved in SPOP-mediated SUFU reduction. Importantly, inhibition of SUFU leads to elevated SHH and WNT signaling, consequently rescuing the reduced proliferation, migration, and invasion abilities of ccRCC cells caused by SPOP-knockdown. Moreover, combinatorial treatment with SHH and WNT inhibitors shows more effective for suppressing ccRCC cell proliferation and aggressiveness. These findings demonstrate that a novel SPOP-PTEN-SUFU axis promotes ccRCC carcinogenesis by activating SHH and WNT pathway, providing a new treatment strategy for ccRCC.
Project description:BackgroundThe non-receptor tyrosine kinase Fyn-related kinase (FRK) has been reported to affect cell proliferation in several cancer types. However, its effect on the proliferation of clear cell renal cell carcinoma (ccRCC) remains largely unknown.PurposeThe objective of this study was to investigate the expression pattern and function of FRK in ccRCC. We further determined how FRK interacted with other molecules to regulate ccRCC proliferation.Patients and methodsThe expression of FRK in ccRCC samples and paired normal renal tissues from 30 patients were analyzed by immunoblotting, immunohistochemistry and quantitative PCR. Then the role of FRK in ccRCC proliferation was analyzed by Cell Counting Kit-8, colony formation assay and EdU incorporation assay. In addition, the miRNA targeting FRK was predicted through a bioinformatic approach and validated by quantitative PCR, immunoblotting and luciferase reporter assay. Finally, the underlying mechanism of FRK regulation of ccRCC proliferation was also determined.ResultsLow expression of FRK was detected in ccRCC samples and predicted poor survival for ccRCC patients. FRK inhibited the proliferation of ccRCC cells via phosphorylating downstream PTEN. miR-19 was identified as a novel suppressor of FRK in renal cancer cells and it promoted the proliferation of ccRCC by inhibiting the FRK-PTEN axis.ConclusionOur results unravel a new regulatory mechanism involved in ccRCC proliferation and may be useful in the identification of therapeutic targets for ccRCC.
Project description:Previous research has found that miRNA-20b is highly expressed in gastric cancer (GC), however, its function and underlying mechanism are not clear. Wnt signaling pathway, implicated in tumorigeneisis, is activated in more than 30% of GC. We would like to characterize the biological behavior of miRNA-20b in terms of modulating Wnt/β-catenin signaling and EMT. We showed that miRNA-20b inhibitors suppressed Topflash/Fopflash dependent luciferase activity and the β-catenin nuclear translocation, resulting in inhibition of Wnt pathway activity and EMT. SUFU, negatively regulating Wnt and Hedgehog signaling pathway, was proved to be targeted by miRNA-20b. Moreover, additional knockdown of SUFU alleviated the inhibitory effect on Wnt pathway activity, EMT, cell proliferation/migration and colony formation caused by miRNA-20b inhibition. In summary, miRNA-20b is an oncogenic miRNA and promoted cell proliferation, migration and EMT in GC partially by activating Wnt pathway via targeting SUFU.
Project description:Rapalogs (everolimus and temsirolimus) are allosteric mTORC1 inhibitors and approved agents for advanced clear cell renal cell carcinoma (ccRCC), although only a subset of patients derive clinical benefit. Progress in genomic characterization has made it possible to generate comprehensive profiles of genetic alterations in ccRCC; however, the correlations between recurrent somatic mutations and rapalog efficacy remain unclear. Here, we demonstrate by using multiple patient-derived ccRCC cell lines that compared to PTEN-proficient cells, PTEN-deficient cells exhibit hypersensitivity to rapalogs. Rapalogs inhibit cell proliferation by inducing G0/G1 arrest without inducing apoptosis in PTEN-deficient ccRCC cell lines. Using isogenic cell lines generated by CRISPR/Cas9, we validate the correlation between PTEN loss and rapalog hypersensitivity. In contrast, deletion of VHL or chromatin-modifying genes (PBRM1, SETD2, BAP1, or KDM5C) fails to influence the cellular response to rapalogs. Our mechanistic study shows that ectopic expression of an activating mTOR mutant (C1483F) antagonizes PTEN-induced cell growth inhibition, while introduction of a resistant mTOR mutant (A2034V) enables PTEN-deficient ccRCC cells to escape the growth inhibitory effect of rapalogs, suggesting that PTEN loss generates vulnerability to mTOR inhibition. PTEN-deficient ccRCC cells are more sensitive to the inhibitory effects of temsirolimus on cell migration and tumor growth in zebrafish and xenograft mice, respectively. Of note, PTEN protein loss as detected by immunohistochemistry is much more frequent than mutations in the PTEN gene in ccRCC patients. Our study suggests that PTEN loss correlates with rapalog sensitivity and could be used as a marker for ccRCC patient selection for rapalog therapy.
Project description:SUFU alterations are commonly detected in human SHH subgroup of medulloblastoma. Here we profile the gene expression of P13 wildtype and Sufu KO cerebellum, as well as Ptch1 KO MB in biological triplicate.
Project description:GLI2 overexpression is a hallmark in SHH subgroup of medulloblastoma (SHH MB). Here we profile the transcriptome of two mouse models of SHH MB expressing high Gli2: SmoM2 overexpression and Sufu;Spop double knockout MB.
Project description:GLI2 overexpression is a hallmark in SHH subgroup of medulloblastoma (SHH MB). Here we identify the targetome of Gli2 in two mouse models of SHH MB: SmoM2 overexpression and Sufu;Spop double knockout MB.
Project description:BackgroundIncreasing evidence has indicated that long noncoding RNAs (lncRNAs) are crucial regulators affecting the progression of human cancers. Recently, lncRNA downregulated in liver cancer stem cells (lnc-DILC) was identified to function as a tumor suppressor inhibiting the tumorigenesis and metastasis in liver cancer and colorectal cancer. However, to date, little is known about the functional roles of lnc-DILC in modulating malignant phenotypes of clear cell renal cell carcinoma (ccRCC) cells.Methodslnc-DILC expression in human ccRCC tissues was detected by qRT-PCR. Overexpression and knockdown experiments were carried out to determine the effects of lnc-DILC on ccRCC cell proliferation, migration and invasion. To reveal the underlying mechanisms of lnc-DILC functions in ccRCC cells. RNA immunoprecipitation, RNA pull-down, in vivo ubiquitination, co-immunoprecipitation and western blot assays were performed.ResultsHere, we identified that lnc-DILC levels were dramatically downregulated in ccRCC tissues. Loss of lnc-DILC expression was correlated with larger tumor size, advanced tumor grade and lymph node metastasis, and also predicted worse prognosis in patients with ccRCC. Functionally, knockdown and overexpression experiments demonstrated that lnc-DILC inhibited cell proliferation, migration and invasion in ccRCC cells. Mechanistic investigation revealed that lnc-DILC bound to tumor suppressor PTEN and suppressed its degradation. lnc-DILC repressed the PTEN ubiquitination through blocking the interaction between PTEN and E3 ubiquitin ligase WWP2 and recruiting the deubiquitinase USP11 to PTEN. Moreover, we demonstrated that PTEN-AKT signaling was crucial for lnc-DILC-mediated suppressive effects.ConclusionsIn summary, our research revealed a novel mechanism by which lnc-DILC regulates PTEN stability via WWP2 and USP11, and shed light on potential therapeutic strategies by the restoration of lnc-DILC expression in patients with ccRCC.
Project description:A multiple receptor tyrosine kinase inhibitor, sunitinib, is a first-line therapy for clear cell renal cell carcinoma (CCRCC). Unfortunately, it has the major challenges of low initial response rate and resistance after about one year of treatment. Here we evaluated a microRNA (miRNA) and its target responsible for sunitinib resistance. Using miRNA profiling, we identified miR-96-5p upregulation in tumors from sunitinib-resistant CCRCC patients. By bioinformatic analysis, PTEN was selected as a potential target of miR-96-5p, which showed low levels in tumors from sunitinib-resistant CCRCC patients. Furthermore, PTEN and miR-96-5p levels were negatively correlated in a large The Cancer Genome Atlas kidney renal clear cell carcinoma cohort and high miR-96 and low PTEN represented poor prognosis in this cohort. Additionally, four-week sunitinib treatment increased miR-96-5p and decreased PTEN only in tumors from a sunitinib-resistant patient-derived xenograft model. We found a novel miR-96-5p binding site in the PTEN 3' UTR and confirmed direct repression by luciferase reporter assay. Furthermore, we demonstrated that repression of PTEN by miR-96-5p increased cell proliferation and migration in sunitinib-treated cell lines. These results highlight the direct suppression of PTEN by miR-96-5p and that high miR-96-5p and low PTEN are partially responsible for sunitinib resistance and poor prognosis in CCRCC.
Project description:Human embryonic stem cell-derived beta cells offer a promising cell-based therapy for diabetes. However, efficient stem cell to beta cell differentiation has proven difficult, possibly due to the lack of cross-talk with the appropriate mesenchymal niche. To define organ-specific niche signals, we isolated pancreatic and gastrointestinal stromal cells, and analyzed their gene expression during development. Our genetic studies reveal the importance of tightly regulated Hedgehog signaling in the pancreatic mesenchyme: inactivation of mesenchymal signaling leads to annular pancreas, whereas stroma-specific activation of signaling via loss of Hedgehog regulators, Sufu and Spop, impairs pancreatic growth and beta cell genesis. Genetic rescue and transcriptome analyses show that these Sufu and Spop knockout defects occur through Gli2-mediated activation of gastrointestinal stromal signals such as Wnt ligands. Importantly, inhibition of Wnt signaling in organoid and human stem cell cultures significantly promotes insulin-producing cell generation, altogether revealing the requirement for organ-specific regulation of stromal niche signals.