ZBRK1, a novel tumor suppressor, activates VHL gene transcription through formation of a complex with VHL and p300 in renal cancer

Abstract

Inactivation or mutation of the VHL gene causes various tumors, including clear cell renal cell carcinoma (ccRCC). In the present study, we identified ZBRK1 as a novel VHL interacting protein by yeast two-hybrid screening, and found a single ZBRK1-binding site located in the VHL promoter region. Ectopic expression of ZBRK1 increases transcriptional activity of the VHL, whereas the depletion of endogenous ZBRK1 by shRNA leads to reduction of VHL expression. We also demonstrate that the inhibition of VEGF transcription by ZBRK1 overexpression is dependent on VHL/HIF pathway. Moreover, VHL is confirmed to serve as a bridge component for the association of ZBRK1 and p300, which leads to an increase in ZBRK1 transcriptional activity in the VHL promoter. We further provide striking evidences that ZBRK1 acts as a tumor suppressor in renal carcinoma by a variety of in vitro and in vivo assays, and ZBRK1 may represent a molecular marker to distinguish patients with ccRCC at high risk from those with a better survival prognosis. Taken together, these findings suggest that ZBRK1 suppresses renal cancer progression perhaps by regulating VHL expression.

Alternative Splicing of EZH2 pre-mRNA by SF3B3 Contributes to the Tumorigenic Potential of Renal Cancer

“…Chromatin immunoprecipitation (ChIP) was performed to investigate whether EZH2 or/and EZH2 binding to HOXA9 promoter. ChIP assays were performed as described previously (38). Final analysis was performed using qPCR and shown as fold enrichment of the HOXA9 gene promoter.…”

“…Tumorgenesis in nude mice was determined as described previously (38). Five mice each were injected subcutaneously with prepared cells at a single site.…”

“…Tumor onset measured with calipers at the site of injection weekly at different times on the same day. The pro-metastatic activity of SF3B3 was tested in the mouse ACHN lung metastasis model as described previously (38). All experiments were approved by the Animal Care and Use Committee of Tongji Medical College of Huazhong University of Science and Technology.…”

TES inhibits colorectal cancer progression through activation of p38

“…For colony formation, as described in earlier studies [68], 1000 cells/well were seeded into 6-well cell culture plates and culture medium was replaced every three days. After 14 days of culture, cells were stained with crystal violet, and the number of visible colonies was counted.…”

The expression signature of cancer‐associated KRAB‐ZNF factors identified in TCGA pan‐cancer transcriptomic data

“…For example, ZNF545 negatively controls cellular proliferation, and its expression is reduced in multiple malignancies due to promoter hypermethylation (Xiang et al ., ; Xiao et al ., ). A tumor suppressor role was also described for ZBRK1 (Chen et al ., ; Lin et al ., ) and ZNF307 (Liang et al ., ). Another member of the KRAB‐ZNF family, ZNF224 , was demonstrated to exert both tumor suppressor and oncogenic functions depending on the cellular context.…”