Tackling Prostate Cancer with basic and translational approaches: exploring intratumoral microbiota and a drug screening for novel enzalutamide-combined therapies

Prostate cancer (PCa) is the second most frequent cancer in men worldwide. In addition to conventional approaches such as surgery, radiation, and chemotherapy, current therapeutic strategies focus on disrupting tumor-intrinsic cellular processes, particularly dysregulated hormone signaling. Androgens fuel the growth of prostate cancer cells, making androgen deprivation therapies (ADT) the election treatment to suppress tumor progression. However, AR-dependent resistance mechanisms often arise, leading to a condition known as castration resistance prostate cancer (CRPC). Metastatic and CRPC diseases exacerbate despite available medications, making PCa an incurable and lethal condition. We carried out a dual research approach to tackle advanced prostate cancer: one focusing on therapeutic interventions through drug screening and the other mining into the fundamental mechanisms of microbiota effect on carcinogenesis. Our first strategy aims to identify a novel drug to be used in combination therapy with the second-generation antiandrogen Enzalutamide. We designed a phenotypic screening to evaluate the compounds' cytotoxicity and synergistic activity in combination with Enzalutamide, which led us to the identification of Compound 74 as the best candidate. Its structure presents a highly redox-active moiety, which we demonstrated to be responsible for its anticancer activity. In parallel, we worked on a second project that seeks to enhance our understanding of tumor-resident bacteria composition throughout cancer progression and possibly reveal its contribution to carcinogenesis. To decipher the intratumoral bacterial presence in prostate cancer, we have optimized a bioinformatic pipeline for detecting intracellular bacteria in single-cell RNAseq data obtained from patients at different disease stages. The analysis of single-cell data has provided a comprehensive picture of intracellular microbiome diversity. We have found enrichment in bacterial infection rate in primary tumor specimens and in metastatic niches. The subsequent in vitro screening reveals bacteria- derived genotoxic effects and the induction of a pro-migratory phenotype upon infection on prostate cancer cells.