EXPLORING HO-1 NON-CANONICAL FUNCTIONS THROUGH ITS NUCLEAR INTERACTORS

ROCIO SENIUK; JUAN BIZZOTTO; SOFIA LAGE VICKERS; PABLO SANCHIS; GASTON PASCUAL; AGUSTINA SABATER; PIA VALACCO; JAVIER COTIGNOLA; GERALDINE GUERON; AYELEN TORO

Congreso; LXVII Reunion Anual de la Sociedad Argentina de Investigación Clínica; 2022

Prostate tumor cells display abnormal expression of proteins resulting in an augmented capacity to resist chemotherapy and colonize distant organs. We have previously shown that heme-oxygenase 1 (HO-1), the rate limiting enzyme in heme degradation, has a strong anti-tumoral effect in prostate cancer (PCa). Several reports indicate that HO-1 translocates to the nucleus as a truncated isoform without enzymatic activity. Regarding its nuclear role, it has been suggested that HO-1 modulates the activity of different transcription factors; however, its non-canonical functions remain unclear. We hypothesize that HO-1 and its nuclear interactors reprogram prostate tumor cells, favoring a less aggressive phenotype. In this work, we carry out a mass spectrometry (MS)-based proteomics analysis to identify HO-1 molecular partners which might collaborate with its non-canonical functions in PCa. PC3 cells were treated with hemin (80 µM for 24 h), a specific pharmacological inducer of HO-1. After nuclear protein isolation, we immunoprecipitated HO-1 and its associated proteins and subjected them to LC-ESI MS/MS analysis. After filtering results with CRAPome we identified 33 proteins in the nuclear fraction of control cells and 34 proteins in the hemin-treated cells. Protein expression analysis reveals 11 differential proteins between control and hemin treated cells. STRING and Ingenuity pathway analysis suggested that the identified HO-1 interactors are implicated in several biological processes such as antioxidant activity, RNA splicing and hydrogen peroxide catabolic processes. Moreover, functions related with scaffold, stemness and gene expression regulation were also identified, pointing out a non-canonical function of nuclear HO-1 in PCa.