Guben Qingyuan Herbal Medicine delays enzalutamide resistance in prostate cancer by alleviating tumor hypoxia and reprogramming energy metabolism in cancer stem cells.

[ETHNOPHARMACOLOGICAL RELEVANCE] Enzalutamide resistance is a major clinical bottleneck limiting the therapeutic efficacy of castration-resistant prostate cancer (CRPC). Enzalutamide treatment can exacerbate tumor hypoxia, which is a critical contributor to the development of its resistance. The traditional Chinese formula Guben Qingyuan Herbal Medicine (GBQY), coupled with enzalutamide, has demonstrated potential in delaying enzalutamide resistance. Nevertheless, its interaction with the tumor microenvironment (TME) remains insufficiently investigated.

[AIM OF THE STUDY] This study aims to explore the anti-tumor role and mechanism of GBQY on CRPC.

[MATERIALS AND METHODS] Enzalutamide-resistant prostate cancer (PC) cell models and corresponding xenograft models were established to evaluate the therapeutic efficacy of GBQY combined with enzalutamide. A hypoxia-sensitive PC xenograft model was constructed to identify hypoxic tumor cell populations in vivo. The correlation between ATP-citrate lyase (ACLY) and hypoxia-inducible factor (HIF)-1α was predicted via bioinformatics analysis and subsequently validated by chromatin immunoprecipitation (ChIP) assay. The impact of hypoxia and ACLY inhibition/knockdown on PC stem cells (PCSCs) was examined using metabolomics. Additionally, a PCSC xenograft model was used to verify the signaling pathways underlying the therapeutic action of GBQY in combination with enzalutamide.

[RESULTS] The combinational therapy of GBQY and enzalutamide significantly delayed the occurrence of enzalutamide resistance. This effect was mediated by alleviating tumor hypoxia, accompanied by attenuated expression of cancer stem cell (CSC) markers CD44 and CD133 in tumor tissues. Xenograft-isolated hypoxia tumor cells consisted of a larger proportion of cells exhibiting CSC-like characteristics. Under hypoxic conditions, elevated HIF-1α levels likely functioned as a transcription factor, upregulating ACLY expression. Subsequent ACLY activation induced a specific energy metabolic reprogramming (EMR), characterized by enhanced glucose uptake and pyruvate production. EMR shifted the glycolytic flux towards mitochondrial pyruvate and citrate, thereby accumulating cytosolic acetyl-CoA via ACLY activity. This metabolic phenotype facilitated β-catenin acetylation, triggering the Wnt/β-catenin signaling cascade crucial to enzalutamide resistance in PC.

[CONCLUSION] These findings provide preclinical evidence supporting the combined application of GBQY and enzalutamide in CRPC treatment. By elucidating the interaction between Traditional Chinese Medicine (TCM) and conventional anti-tumor therapy within TME, this study offers mechanistic insights into resistance modulation and paves the way to optimizing the precision of TCM-based therapeutic strategies in PC management.