CLINICAL RELEVANCE OF ANNEXIN 2 IN PROSTATE CANCER BONE METASTASIS AND ITS ASSOCIATION WITH HEME-OXYGENASE 1

ANSELMINO NICOLAS; ORTIZ EMILIANO; ELBA VAZQUEZ; PAEZ ALEJANDRA; COTIGNOLA JAVIER; DAIANA LEONARDI; GERALDINE GUERON

Congreso; Reunion anual de la Sociedad Argentina de Investigacion Clinica; 2016

SAIC

HO-1 is a critical mediator of cellular homeostasis. In prostate cancer (PCa) HO-1 may have a regulatory role beyond its enzymatic activity. We screened for HO-1 interacting proteins using a proteomics approach. PC3 cells were transiently transfected with FLAGHO-1, treated with H2O2 and the immunoprecipitated protein complexes were subjected to LC-ESI MS/MS. Proteomics analysis revealed the presence of annexin2 (ANXA2) among HO-1 interacting proteins. Interestingly ANXA2 was significantly downregulated across the Oncomine database in prostate adenocarcinoma vs. normal prostate gland, lying within the 13 lowest ranked genes, with a P-value of 0.003. We also screened for HO-1 and ANXA2 expression in PCa tissue micro arrays (TMAs). When assessing HO-1 across the different TNM staging system, the rate of positive cases was higher in T2-T3 N0M0 compared to T2-T3 with spreading to regional lymph nodes or the presence of distant metastasis. A reduction in ANXA2 positive staining was detected between normal prostate and adenocarcinoma. Given that bone is the most common homing organ in PCa metastasis, we assessed ANXA2 expression levels using a co-culture transwell system of PC3 and the pre-osteoclastic Raw264.7 cell lines. When cells were co-cultured, ANXA2 mRNA levels were detected significantly upregulated in PC3 cells and diminished in Raw264.7. Immunofluorescence analysis has shown there was a clear re-localization of ANXA2 in Raw264.7 towards the cell cytosolic compartment under co-culture conditions, with a concomitant reduction in cell membrane immunostaining. Interestingly, hemin pre-treatment of tumoral cells prevented these effects. Given the tight association between ANXA2 and cell adhesiveness, HO-1 induction in PCa cells may force bone cells to keep ANXA2 in the cell membrane, preventing the attachment of tumoral cells to the bone niche, impairing bone metastasis.