Unveiling the molecular significance of HO-1 and muskelin interaction: two masterminds behind the morphology and the adhesive behavior of prostate cancer cells

GUERON, GERALDINE; GIUDICE, JIMENA; PAEZ,ALEJANDRA ; VALACCO, PIA; CARABELOS, NOELIA; SCHUSTER, FEDERICO; COTIGNOLA, JAVIER; JAWORSKI, FELIPE; LEONARDI, DAIANA; BINAGHI, MARIA; MARTI, MARCELO; NAVONE, NORA; VAZQUEZ, ELBA

San Diego

Congreso; AACR Annual Meeting 2014; 2014

American Asociation for Cancer Research

Prostate Cancer (PCa) is the second leading cause of cancer death in American men. The inflammatory tumor microenvironment is a fertile niche that releases reactive oxygen species, which accelerates the malignant transformation and appears as a fine tuner of the adhesive behavior of cells. Heme oxygenase 1 (HO-1), the rate-limiting enzyme in heme degradation, represents an essential event in cellular responses to pro-oxidative and pro-inflammatory insults. As we previously reported that HO-1 over-expression impaired tumor growth and angiogenesis in vivo we sought to assess whether HO-1 could regulate the adhesive properties and the morphology of PCa cells. A bioinformatics enrichment analysis using Metacore, GeneMANIA and DAVID was performed; rendering a significant association of the HO-1 regulated genes with several proteins located in the extracellular space and cell membrane; compartments highly correlated with the adhesive behavior of cells. In an effort to understand the molecular mechanisms underlying HO-1?s role in cell morphology regulation we used a proteomics approach to identify HO-1 partners. We performed GST-pulldown assays using lysates from PC3 cells transfected with either GST-tagged HO-1 or the empty vector, and the isolated proteins were subjected to MALDI-TOF/TOF analyses. Our results showed that HO-1 interacts with Muskelin, a nucleocytoplasmic mediator of cellular morphology and adhesiveness. Up-regulation of Muskelin under HO-1 induction in PCa cells was confirmed by confocal microscopy. A high degree of nuclear overlay between HO-1 and Muskelin signals was observed when cells were exposed to hemin, a potent specific inducer of HO-1 or genetically manipulated to overexpress HO-1, compared to controls. Interestingly after HO-1 induction, both protein exhibit similar sub-cellular dynamics, relocating from the cell membrane, towards the cell nuclei. Altogether, we have shown for the first time that HO-1 binds and up-regulates Muskelin, a specific factor involved in shaping cellular morphology and adhesive properties, favoring a less aggressive phenotype and further supporting the antitumoral function of HO-1in PCa.