Differentiation-associated urothelial cytochrome P450 oxidoreductase predicates the xenobiotic-metabolising activity of "luminal" muscle-invasive bladder cancers

TY - JOUR

T1 - Differentiation-associated urothelial cytochrome P450 oxidoreductase predicates the xenobiotic-metabolising activity of "luminal" muscle-invasive bladder cancers

AU - Baker, Simon C

AU - Arlt, Volker M

AU - Indra, Radek

AU - Joel, Madeleine

AU - Stiborova, Marie

AU - Eardley, Ian

AU - Ahmad, Niaz

AU - Otto, Wolfgang

AU - Burger, Maximilian

AU - Rubenwolf, Peter

AU - Phillips, David H

AU - Southgate, Jennifer

N1 - This article is protected by copyright. All rights reserved.

PY - 2018/5

Y1 - 2018/5

N2 - Extra-hepatic metabolism of xenobiotics by epithelial tissues has evolved as a self-defence mechanism but has potential to contribute to the local activation of carcinogens. Bladder epithelium (urothelium) is bathed in excreted urinary toxicants and pro-carcinogens. This study reveals how differentiation affects cytochrome P450 (CYP) activity and the role of NADPH:P450 oxidoreductase (POR). CYP1A1 and CYP1B1 transcripts were inducible in normal human urothelial (NHU) cells maintained in both undifferentiated and functional barrier-forming differentiated states in vitro. However, ethoxyresorufin O-deethylation (EROD) activity, the generation of reactive BaP metabolites and BaP-DNA adducts, were predominantly detected in differentiated NHU cell cultures. This gain-of-function was attributable to the expression of POR, an essential electron donor for all CYPs, which was significantly upregulated as part of urothelial differentiation. Immunohistology of muscle invasive bladder cancer (MIBC) revealed significant overall suppression of POR expression. Stratification of MIBC biopsies into "luminal" and "basal" groups, based on GATA3 and cytokeratin 5/6 labelling, showed POR over-expression by a subgroup of the differentiated luminal tumours. In bladder cancer cell lines, CYP1-activity was undetectable/low in basal PORlo T24 and SCaBER cells and higher in the luminal POR over-expressing RT4 and RT112 cells than in differentiated NHU cells, indicating that CYP-function is related to differentiation status in bladder cancers. This study establishes POR as a predictive biomarker of metabolic potential. This has implications in bladder carcinogenesis for the hepatic versus local activation of carcinogens and as a functional predictor of the potential for MIBC to respond to prodrug therapies. This article is protected by copyright. All rights reserved.

AB - Extra-hepatic metabolism of xenobiotics by epithelial tissues has evolved as a self-defence mechanism but has potential to contribute to the local activation of carcinogens. Bladder epithelium (urothelium) is bathed in excreted urinary toxicants and pro-carcinogens. This study reveals how differentiation affects cytochrome P450 (CYP) activity and the role of NADPH:P450 oxidoreductase (POR). CYP1A1 and CYP1B1 transcripts were inducible in normal human urothelial (NHU) cells maintained in both undifferentiated and functional barrier-forming differentiated states in vitro. However, ethoxyresorufin O-deethylation (EROD) activity, the generation of reactive BaP metabolites and BaP-DNA adducts, were predominantly detected in differentiated NHU cell cultures. This gain-of-function was attributable to the expression of POR, an essential electron donor for all CYPs, which was significantly upregulated as part of urothelial differentiation. Immunohistology of muscle invasive bladder cancer (MIBC) revealed significant overall suppression of POR expression. Stratification of MIBC biopsies into "luminal" and "basal" groups, based on GATA3 and cytokeratin 5/6 labelling, showed POR over-expression by a subgroup of the differentiated luminal tumours. In bladder cancer cell lines, CYP1-activity was undetectable/low in basal PORlo T24 and SCaBER cells and higher in the luminal POR over-expressing RT4 and RT112 cells than in differentiated NHU cells, indicating that CYP-function is related to differentiation status in bladder cancers. This study establishes POR as a predictive biomarker of metabolic potential. This has implications in bladder carcinogenesis for the hepatic versus local activation of carcinogens and as a functional predictor of the potential for MIBC to respond to prodrug therapies. This article is protected by copyright. All rights reserved.

UR - http://www.scopus.com/inward/record.url?scp=85041225660&partnerID=8YFLogxK

U2 - 10.1002/mc.22784

DO - 10.1002/mc.22784

M3 - Article

C2 - 29323757

SN - 0899-1987

VL - 57

SP - 606

EP - 618

JO - Molecular Carcinogenesis

JF - Molecular Carcinogenesis

IS - 5

ER -