Abstract 2787: Heme oxygenase 1 pulls the brake on stemness-induced properties by prostate cancer-bone crosstalk

Abstract Prostate cancer (PCa) is the second most diagnosed cancer in men globally, and it is positioned as the fifth leading cause of cancer-related death in males. PCa aggressiveness and mortality is intricately linked to the metastatic disease, which is propelled by PCa stem cells (PCSCs). We have previously showcased the strong antitumoral role heme oxygenase-1 (HO-1) exerts in PCa. However, little is known about the association of HO-1 with the stemness capacity of PCa cells. In this work, we first performed clonogenic assays in PCa cells (PC3 and C4-2B) to assess colony formation, which evidenced a reduction on the stem-like properties of tumor cells treated with hemin (FDA approved drug and specific HO-1 inducer and activator). Next, we employed an indirect co-culture system of PCa cells (PC3) grown with bone progenitors (MC3T3) to emulate the dynamic PCa-bone crosstalk. PC3 cells were pre-treated or not with hemin. We performed comprehensive RNA-seq analyses and assessed the transcriptome of PC3 cells focusing on genes associated with stemness (CD44, CD133 and other pluripotency markers), metastasis and a stem-like signature previously identified by our group (ADAM15, BCL2L1, LTBR, MBNL2, SPINT1). PC3 cells that were co-cultured with MC3T3 displayed upregulated PCSC and pluripotency markers, as well as BCL2L1 and LTBR, when compared with PC3 cells cultured alone. Intriguingly, pre-treatment of PC3 cells with hemin prior to the co-culture impaired the upregulation of these genes, including the PCSC marker CD44, underscoring the protective effect of HO-1 induction against the pro-stemness effect triggered by bone progenitors secreted factors. Furthermore, we extended our analysis using PCa patients’ survival and transcriptomic publicly available data (TCGA-PRAD (n=565), SU2C-PRAD (n=444), FHCRC-PRAD (n=176)), which revealed that ADAM15, BCL2L1, LTBR and SPINT1 expression was higher in bone metastases vs. primary PCa (p<0.001). Moreover, POU5F1, ALDH1L2, ADAM15, BCL2L1, LTBR and SPINT1 presented higher expression in bone metastases vs. other sites of metastasis (p<0.01). We also performed multiple survival analyses including progression-free, metastasis-free, biochemical relapse-free and overall survival (TCGA-PRAD, GSE116918, GSE70770) which revealed that CD44 expression is associated with increased risk of metastasis (p<0.05), while patients with high expression of SOX2, ALDH1B1 and ALDH1L2 showed shorter times to biochemical relapse (p<0.05) Altogether, HO-1 expression modulates stemness and metastasis-related genes in PCa cells, steering tumor cells towards a more differentiated state and counteracting the pro-stemness effect inherent to the communication with bone progenitors. These findings support the antitumoral role of HO-1 in PCa and underscores CD44 as an HO-1-modulated compelling candidate for further investigations. Citation Format: Agustina Ayelen Sabater, Ines Achinelli, Pablo Sanchis, Nicolas Anselmino, Juan Bizzotto, Gaston Pascual, Rocio Seniuk, Javier Cotignola, Elba Vazquez, Geraldine Gueron, Ayelen Toro. Heme oxygenase 1 pulls the brake on stemness-induced properties by prostate cancer-bone crosstalk [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2787.