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posted on 2025-11-26, 13:40 authored by Pamela J. Maxwell, Melanie McKechnie, Christopher W. Armstrong, Judith M. Manley, Chee Wee Ong, Jenny Worthington, Ian G. Mills, Daniel B. Longley, James P. Quigley, Amina Zoubeidi, Johann S. de Bono, Elena Deryugina, Melissa J. LaBonte, David J.J. Waugh <p>Inhibition of VEGF and IL8 enhances tumor sensitivity to enzalutamide <i>in vivo.</i> For all experiments, male <i>Balb</i>/c SCID mice bearing tumors of 100 to 150 mm<sup>3</sup> were assigned to the following treatment groups for 28 days: Vehicle; enzalutamide (Enz; 4 mg/kg) + IgG control (150 μg/mL); Vehicle + anti-VEGF nAb (100 μg/mL) and anti-IL8 (50 μg/mL) nAbs; and Enz (4 mg/mL) + anti-VEGF (100 μg/mL), and anti-IL8 (50 μg/mL) nAbs. <b>A</b> and <b>B,</b> Tumor growth data, obtained by measuring (<b>A</b>) LNCaP-PAR and (<b>B</b>) LNCaP-EnzR tumor volume every 2 days. The treatment schematic is shown above the graph. The data points represent the mean ± SD (<i>N</i> = 8/group). <b>C</b> and <b>D,</b> Normalized bodyweight (at end of treatment) of mice with (<b>C</b>) LNCaP-PAR and (<b>D</b>) LNCaP-EnzR tumors treated with Enz alone or in combination with anti-VEGF nAb and anti-IL8 nAb. Values shown are mean ± SD (<i>N</i> = 8/group). <b>E</b> and <b>F,</b> Intratumoral oxygenation concentration (mmHg) in (<b>E</b>) LNCaP-Par and <b>(F</b>) LNCaP-EnzR <i>in vivo</i> tumors (<i>N</i> = 4/group) treated with Enz alone or in combination with anti-VEGF nAb and anti-IL8 nAb for 29 days and measured time-dependent changes. For all experiments, statistical analysis was carried out using a 2-way ANOVA with Tukey post-hoc test: *, <i>P <</i> 0.05; **, <i>P <</i> 0.01; ***, <i>P <</i> 0.001.</p>
Funding
Movember
Prostate Cancer UK Centre of Excellence Award
Prostate Cancer UK
Department of Employment and Learning
Harold Porter Scholarship
Queen's University Belfast Travel Bursary
Men Against Cancer
History
ARTICLE ABSTRACT
Inhibiting androgen signaling using androgen signaling inhibitors (ASI) remains the primary treatment for castrate-resistant prostate cancer. Acquired resistance to androgen receptor (AR)-targeted therapy represents a major impediment to durable clinical response. Understanding resistance mechanisms, including the role of AR expressed in other cell types within the tumor microenvironment, will extend the clinical benefit of AR-targeted therapy. Here, we show the ASI enzalutamide induces vascular catastrophe and promotes hypoxia and microenvironment adaptation. We characterize treatment-induced hypoxia, and subsequent induction of angiogenesis, as novel mechanisms of relapse to enzalutamide, highlighting the importance of two hypoxia-regulated cytokines in underpinning relapse. We confirmed AR expression in CD34+ vascular endothelium of biopsy tissue and human vascular endothelial cells (HVEC). Enzalutamide attenuated angiogenic tubule formation and induced cytotoxicity in HVECs in vitro, and rapidly induced sustained hypoxia in LNCaP xenografts. Subsequent reoxygenation, following prolonged enzalutamide treatment, was associated with increased tumor vessel density and accelerated tumor growth. Hypoxia increased AR expression and transcriptional activity in prostate cells in vitro. Coinhibition of IL8 and VEGF-A restored tumor response in the presence of enzalutamide, confirming the functional importance of their elevated expression in enzalutamide-resistant models. Moreover, coinhibition of IL8 and VEGF-A resulted in a durable, effective resolution of enzalutamide-sensitive prostate tumors. We conclude that concurrent inhibition of two hypoxia-induced factors, IL8 and VEGF-A, prolongs tumor sensitivity to enzalutamide in preclinical models and may delay the onset of enzalutamide resistance.
Targeting hypoxia-induced signaling may extend the therapeutic benefit of enzalutamide, providing an improved treatment strategy for patients with resistant disease.
