Heterogeneous nuclear ribonucleoprotein K is associated with poor prognosis and regulates proliferation and apoptosis in bladder cancer

Abstract

Heterogeneous nuclear ribonucleoprotein K (hnRNPK) is an essential RNA‐ and DNA‐binding protein that regulates diverse biological events, especially DNA transcription. hnRNPK overexpression is related to tumorigenesis in several cancers. However, both the expression patterns and biological mechanisms of hnRNPK in bladder cancer are unclear. We investigated hnRNPK expression by immunohistochemistry in 188 patients with bladder cancer, and found that hnRNPK expression levels were significantly increased in bladder cancer tissues and that high‐hnRNPK expression was closely correlated with poor prognosis. Loss‐ and gain‐of‐function assays demonstrated that hnRNPK promoted proliferation, anti‐apoptosis, and chemoresistance in bladder cancer cells in vitro, and hnRNPK knockdown suppressed tumorigenicity in vivo. Mechanistically, hnRNPK regulated various functions in bladder cancer by directly mediating cyclin D1, G0/G1 switch 2 (G0S2), XIAP‐associated factor 1, and ERCC excision repair 4, endonuclease catalytic subunit (ERCC4) transcription. In conclusion, we discovered that hnRNPK plays an important role in bladder cancer, suggesting that it is a potential prognostic marker and a promising target for treating bladder cancer.

Long Noncoding RNA LBCS Inhibits Self-Renewal and Chemoresistance of Bladder Cancer Stem Cells through Epigenetic Silencing of SOX2

“…The chemosensitivity assay and apoptosis analysis were performed as described previously (23)(24)(25) and as detailed in the Supplementary Materials and Methods section. Caspase-3/7 activity was measured using a Caspase-Glo 3/7 Assay kit (Promega) as previously described (23,24).…”

“…The chemosensitivity assay and apoptosis analysis were performed as described previously (23)(24)(25) and as detailed in the Supplementary Materials and Methods section. Caspase-3/7 activity was measured using a Caspase-Glo 3/7 Assay kit (Promega) as previously described (23,24). The terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay was conducted using the In Situ Cell Death Detection Kit (Roche), following the manufacturer's instructions and as described previously (25).…”

“…Lnc-LBCS expression was also examined using ISH in formalin-fixed, paraffin-embedded (FFPE) samples, as previously described (26) and as detailed in the Supplementary Materials and Methods section. The IHC analyses and score calculation were conducted as described previously (23,24). Anti-SOX2 antibodies (1:500) were used to detect the expression of SOX2 in bladder cancer tissues.…”

“…Anti-SOX2 antibodies (1:500) were used to detect the expression of SOX2 in bladder cancer tissues. The expression of lnc-LBCS and SOX2 in bladder specimens was quantified by using the histochemical score (H-score) as described previously (23,24). The staining intensity was graded as follows: 0 (no staining), 1 (weak staining, light yellow for IHC, light blue for ISH), 2 (moderate staining, brown for IHC, moderate blue for ISH), and 3 (strong staining, brown red for IHC, strong blue for ISH).…”

“…The chromatin isolation by RNA purification (ChIRP) was conducted using a Magna ChIRP RNA Interactome kit (Millipore) according to the manufacturer's instructions and as described previously (25). Chromatin immunoprecipitation (ChIP) was conducted using an EZ-Magna ChIP A/G kit (Millipore) according to the manufacturer's instructions and as previously reported (23)(24)(25). The method of ChIRP and ChIP was detail in the Supplementary Materials and Methods section.…”