Unraveling the anti-angiogenic properties of HO-1 in prostate cancer.

GUERON G; FERRANDO M; ELGUERO B; GIUDICE J; LABANCA E; COLOMBO L; MEISS R; NAVONE N; DE SIERVI A; VAZQUEZ E

Edimburgo

Congreso; 7th INTERNATIONAL MEETING ON HEME OXYGENASE & RELATED ENZYMES; 2012

Prostate cancer (PCa) is a leading cause of death among males. Angiogenesis is critical during tumor initiation and progression. Heme oxygenase-1 (HO-1) counteracts oxidative and inflammatory damage. It has become increasingly clear that in addition to its effect on blocking proliferation, invasion and migration, other mechanisms including a direct effect on angiogenic factors may account for its anti-tumoral role in PCa.  To further assess its properties, we investigated its potentiality to modulate PCa associated-angiogenesis. In this study, we identified in PCa cells a set of pro-angiogenic genes down-regulated in response to HO-1 overexpression, in particular VEGFA, VEGFC, HIF1a and a5b1 integrin. Moreover, intracellular DCFHDA staining method revealed that HO-1 counteracts oxidative imbalance reducing ROS levels assessed by cell by cell immunofluorescence quantification. An in vivo angiogenic assay showed that intradermal inoculation of PC3 cells stable transfected with HO-1 (PC3HO-1) generated tumours less vascularised than controls, with decreased microvessel density and reduced CD34 and MMP9 positive staining.  Longer term grown PC3HO-1 xenografts also displayed reduced neovascularization with down-regulation of VEGFR2 expression. Furthermore, immunofluorescence and structured illumination microscopy showed NFkB retention in cytoplasm and demonstrated a higher rate of co-localization with HO-1 under HO-1 over-expression. These observations correlated with repressed NF-kB-mediated transcription from an NF-kB responsive luciferase reporter construct, induced accumulation of IkB and decreased IKK mRNA levels. Taken together, these data supports an unprecedented role of HO-1, challenging the angiogenic-switch in prostate carcinogenesis outlining a rationale for its development as an anticancer target in PCa.