Abstract 2437: HMOX1 modulates tumor stemness and metastatic properties in prostate cancer
Authors: Sabater Agustina A. , Toro Ayelen R. , Sanchis Pablo A. , Pascual Gaston M. , Seniuk Rocio A. , Vazquez Elba S. , Cotignola Javier , Bizzotto Juan A. , Lage-Vickers Sofia , Gueron Geraldine 
Published: April 2023

Abstract
Eighty percent of prostate cancers (PCa) metastasize to bone, showing a significant source of patient morbidity. PCa stem-like cells (PCSCs) are capable to quiescently outlast retaining the ability to proliferate and regenerate, consequently remaining able to develop therapy-resistant tumors and metastatic lesions. We have previously reported that the overexpression of heme oxygenase 1 (HO-1), the rate limiting enzyme in heme degradation, leads to a less aggressive PCa phenotype. However, its effect on metastasis-stemness (MS) remains unknown. In this work, we address the biological significance of HO-1 in association with relevant MS genes for PCa progression. Clonogenic assays performed in PCa cells (PC3 and C4-2B) to assess colony formation, evidenced a reduction on the stem-like properties of tumor cells treated with hemin (FDA approved drug and specific HO-1 inducer). RNA-seq analysis to identify MS genes that could be modulated by HO-1 induction, revealed 32 MS-genes that were modulated in PC3-hemin vs. PC3-control cells. We then mined the Oncomine database (n = 1,128) and found that 15/32 HO-1-modulated MS genes were significantly dysregulated in PCa compared with normal gland. To extend our findings, further computational analyses were conducted, and a custom-made bioinformatics tool (Gene Hunter) was created to analyze gene expression and clinicopathological profiles across multiple publicly available PCa datasets with normal, adjacent, tumoral and metastatic samples (n = 1,629). We found that ADAM15, BCL2L1, LTBR, MBNL2 and SPINT1 are consistently dysregulated across different comparisons, with expression profiles in tumors that could be reverted by hemin treatment, according to our RNA-seq results. We constructed a risk score that efficiently stratified patients in high, intermediate and low-risk of biochemical-relapse groups (p&lt;0.01). We also performed multiple survival analyses including, overall, progression-free, relapse-free and metastasis-free survival data. We found that high MBNL2, a gene previously reported to be related to embryonic stem cell differentiation and to antimetastatic effects in other tumors, was associated with lower risk of relapse, progression and metastasis (p&lt;0.05). Of note, the expression of MBNL2 was downregulated in PCa samples compared with normal gland or normal adjacent tissue. Interestingly MBNL2 expression can be reverted by HO-1 induction in PCa cells, as validated by RT-qPCR. Accordingly, those patients with high expression of MBNL2 showed a decreased risk of biochemical-relapse when they presented high HMOX1 levels (HR = 0.4615, p = 0.0186). Altogether, we highlight the relevance of HO-1 in modulating MS-associated genes in PCa and point out to MBNL2 as a potential druggable target for disease intervention.
Citation Format: Agustina A. Sabater, Ayelen R. Toro, Pablo A. Sanchis, Gaston M. Pascual, Rocio A. Seniuk, Elba S. Vazquez, Javier Cotignola, Juan A. Bizzotto, Sofia Lage-Vickers, Geraldine Gueron. HMOX1 modulates tumor stemness and metastatic properties in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2437.