USP13 functions as a tumor suppressor by blocking the NF-kB-mediated PTEN downregulation in human bladder cancer
Xiaojun Man1, Chiyuan Piao1, Xuyong Lin2
1Department of Urology, First hospital of China Medical University, No.155 Nanjing north Road, Shenyang, 110001, Liaoning, China.
Background:
USP13 has been reported to be involved in the tumorigenesis of human cancers, however, its functional role and regulatory mechanisms in bladder cancer (BC) remain unclear.
Methods:
q-RT-PCR was performed to examine the expression of miR-130b-3p, miR-301b-3p and USP13 in BC tissue samples. Western blot, q-RT-PCR, bioinformatic analysis and dual-luciferase reporter assay were conducted to identify the regulatory function of miR-130b-3p/301b-3p for USP13. Co-immunoprecipitation assay was performed to assess the interaction between USP13 and PTEN protein. Cell-counting-kit 8, colony formation assay and transwell assay were performed to value the proliferative, migrative and invasive capacities of BC cells in vitro. Mouse xenograft model of BC cells was established to verify the function of USP13 in vivo. Immunohistochemistry was performed to identify the protein expression of USP13, NF-kB p65 or PTEN in clinical/xenograft tumor tissues.
Results:
Our present study reveals that USP13 functions as a tumor suppressor by interacting with PTEN protein and increasing its expression in bladder cancer. We found that loss of USP13 led to the downregulation of PTEN and promoted proliferative, invasive and migrative capacities of bladder cancer cells. Furthermore, we discovered that USP13 was a common target of miR-130b-3p and miR-301b-3p, and the miR-130b/301b cluster, which could be transcriptionally upregulated by NF-kB. Our data demonstrated that NF-kB activation decreased expression level of USP13 and PTEN, and promoted the tumorigenesis phenotypes of BC cells. In addition, reintroduction of USP13 partially rescued PTEN expression as well as the oncogenesis trend caused by NF-kB.
Conclusion:
We reported a potential regulatory loop that the NF-kB-induced miR-130b/301b overexpression decreased USP13 expression and subsequently resulted in the downregulation of PTEN protein and promoted tumorigenesis of bladder cancer. Moreover, NF-kB-mediated PTEN downregulation is very likely to facilitate the full activation of NF-kB.
Insights
USP13 acts as a tumor suppressor in bladder cancer by stabilizing PTEN. Its downregulation by NF-kB-activated microRNAs promotes cancer progression, highlighting a novel regulatory loop.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Ubiquitin-specific peptidase 13 (USP13) is implicated in human cancer tumorigenesis.
- Its precise function and regulatory pathways in bladder cancer (BC) remain largely uncharacterized.
Purpose of the Study:
- To elucidate the role of USP13 in bladder cancer.
- To identify the regulatory mechanisms governing USP13 expression and function in BC.
Main Methods:
- Quantitative real-time PCR (q-RT-PCR) and Western blot analyses were employed.
- Bioinformatic analysis, dual-luciferase reporter assays, and co-immunoprecipitation were performed.
- In vitro cell proliferation, migration, invasion assays, and in vivo mouse xenograft models were utilized.
Main Results:
- USP13 functions as a tumor suppressor in bladder cancer by interacting with and stabilizing PTEN.
- Loss of USP13 promotes BC cell proliferation, migration, and invasion.
- USP13 is a target of miR-130b-3p and miR-301b-3p, which are upregulated by NF-kB, leading to decreased USP13 and PTEN levels and promoting tumorigenesis.
Conclusions:
- A regulatory loop involving NF-kB, miR-130b/301b, USP13, and PTEN in bladder cancer was identified.
- NF-kB activation upregulates miR-130b/301b, decreasing USP13 and PTEN, thereby promoting bladder cancer progression.
- This pathway suggests a mechanism where PTEN downregulation facilitates further NF-kB activation.
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