CD73 inhibition overcomes adaptive immune resistance to PARP inhibition in models of prostate cancer
Ping Xie, Renqiang Ma, Minghui Zhang, Jie Fan, Hui Tang, Longzhen Song, Yong Wan, Timothy M. Kuzel, Deyu Fang, Weiguo Cui, Jennifer D. Wu, Sarki A. Abdulkadir, Yi Zhang, Akash Patnaik, Bin Zhang
Ping Xie, Renqiang Ma, Minghui Zhang, Jie Fan, Hui Tang, Longzhen Song, Yong Wan, Timothy M. Kuzel, Deyu Fang, Weiguo Cui, Jennifer D. Wu, Sarki A. Abdulkadir, Yi Zhang, Akash Patnaik, Bin Zhang
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Research Article Immunology Oncology

CD73 inhibition overcomes adaptive immune resistance to PARP inhibition in models of prostate cancer

Abstract

Metastatic castration-resistant prostate cancer (mCRPC) remains a leading cause of cancer-related mortality in men. Although poly(ADP-ribose) polymerase (PARP) inhibitors are approved for mCRPC patients with homologous recombination repair (HRR) deficiencies, clinical trials combining olaparib with PD-1/PD-L1 inhibitors showed limited efficacy in unselected populations. To investigate the immunomodulatory effects of PARP inhibitors in an unbiased manner, we performed bulk RNA-seq on HRR-proficient MycCaP cells treated with the PARP inhibitor olaparib versus vehicle control. Transcriptomic analysis revealed robust upregulation of CD73 (NT5E), an ectoenzyme and emerging immune checkpoint that generates extracellular adenosine, suggesting an adaptive mechanism that undermines olaparib efficacy and promotes immunosuppression. CD73 induction by olaparib was validated in human and mouse prostate cancer cell lines, with more pronounced effects in HRR-compromised PTEN-KO cells. Mechanistically, olaparib-driven CD73 expression was mediated through DNA damage–activated ATR/CHEK1/IRF1 and TGF-β1/AKT signaling pathways. In parallel, olaparib enhanced tumor immunogenicity by activating type I IFN signaling and antigen presentation machinery. In vivo, combining olaparib with CD73 blockade significantly delayed tumor growth, improved T cell infiltration, and augmented CD8+ T cell effector function across HRR-proficient and PTEN-KO prostate cancer models. These findings identify olaparib-induced CD73 upregulation as an adaptive resistance mechanism and support olaparib plus CD73 blockade as a promising therapeutic strategy for advanced prostate cancer, irrespective of HRR status.

Authors

Ping Xie, Renqiang Ma, Minghui Zhang, Jie Fan, Hui Tang, Longzhen Song, Yong Wan, Timothy M. Kuzel, Deyu Fang, Weiguo Cui, Jennifer D. Wu, Sarki A. Abdulkadir, Yi Zhang, Akash Patnaik, Bin Zhang

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Figure 2

PARPi induces tumor CD73 expression through ATR–IRF1 signaling.

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PARPi induces tumor CD73 expression through ATR–IRF1 signaling. (A) Flow...
(A) Flow cytometry analysis of p-H2AX levels in MycCaP cells following olaparib treatment. (B) Immunofluorescence staining showing spatial localization patterns of p-H2AX (green) and CD73 (purple) in MycCaP cells. Scale bar: 50 μm. (C) Flow cytometry assessment of the relationship between CD73 and p-H2AX signal intensity in MycCaP cells. (D) GSEA revealing enrichment of homologous recombination and ATR-associated pathways in MycCaP cells following olaparib treatment. (E) Flow cytometry analysis of CD73 expression in MycCaP and MycCaP-PTEN–KO cells pretreated with ATR inhibitor, ATM inhibitor, or the combination for 30 minutes before olaparib exposure. (F) RT-qPCR measurement of Irf1 mRNA levels in MycCaP and MycCaP-PTEN–KO cells after olaparib treatment at 10, 20, or 50 μM. (G) ChIP analysis of IRF1 binding to 2 regions of the Nt5e promoter in MycCaP cells treated with olaparib, an ATR inhibitor, or the combination. (H) Flow cytometry assessment of CD73 levels in IRF1-KD versus nontargeting control (NT) MycCaP and MycCaP-PTEN–KO cells following olaparib treatment. (I) Flow cytometry analysis of CD73 expression in IRF1-KO MycCaP cells pretreated with an ATR inhibitor, followed by 20 μM olaparib treatment for 24 hours, compared with NT control MycCaP cells. Results are representative of 2 (A, F, and G) or 3 (C, E, H, and I) independent experiments. Data were analyzed by unpaired 2-tailed Student’s t test (C and D), 1-way ANOVA with Tukey’s post hoc correction (A and F), or 2-way ANOVA with Tukey’s post hoc correction (E and G–I). Data plotted are mean ± SEM from biological replicates. *P < 0.05, **P < 0.01, ***P < 0.001.