Search

Despite the development of second-generation antiandrogens, acquired resistance to hormone therapy remains a major challenge in treating advanced prostate cancer. We find that cancer-associated fibroblasts (CAFs) can promote antiandrogen resistance in mouse models and in prostate organoid cultures. We identify neuregulin 1 (NRG1) in CAF supernatant, which promotes resistance in tumor cells through activation of HER3. Pharmacological blockade of the NRG1/HER3 axis using clinical-grade blocking antibodies re-sensitizes tumors to hormone deprivation in vitro and in vivo. Furthermore, patients with castration-resistant prostate cancer with increased tumor NRG1 activity have an inferior response to second-generation antiandrogen therapy. This work reveals a paracrine mechanism of antiandrogen resistance in prostate cancer amenable to clinical testing using available targeted therapies., Competing Interests: Declaration of Interests C.L.S. and J.W. are co-inventors of enzalutamide and apalutamide and may be entitled to royalties. C.L.S. serves on the Board of Directors of Novartis and is a co-founder of ORIC Pharmaceuticals. He is a science advisor to Agios, Beigene, Blueprint, Column Group, Foghorn, Housey Pharma, Nextech, KSQ, Petra, and PMV. W.A. reports consulting for Clovis Oncology, Janssen, MORE Health, and ORIC Pharmaceuticals, and received honoraria from CARET and travel accommodations from GlaxoSmith Kline, Clovis Oncology, and ORIC Pharmaceuticals. D.E.R. reports having consulting or advisory role (uncompensated) from Genentech/Roche, Janssen Oncology, and TRACON Pharma, and received research funding from: AstraZeneca (Inst); Celgene (Inst); Ferring (Inst); Genentech/Roche (Inst); Janssen Oncology (Inst); Medivation/Astellas/Pfizer (Inst); Millennium (Inst); Novartis (Inst); Taiho Pharmaceutical (Inst); Takeda (Inst); TRACON Pharma (Inst). W.R.K. is a coinventor on patent WO2012168930A2 filed by Koninklijke Nederlandse Akademie Van Wetenschappen that covers organoid technology., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

In this issue of Cancer Cell, Lee and colleagues (2016) define the biologic role of MYCN in promoting prostate tumorigenesis and development of a neuroendocrine phenotype. This has important implications for the clinical management of neuroendocrine prostate cancer as Aurora A kinase inhibitors promoting N-Myc destabilization progress in the clinic., (Copyright © 2016 Elsevier Inc. All rights reserved.)

In PTEN-mutated tumors, we show that PI3Kα activity is suppressed and PI3K signaling is driven by PI3Kβ. A selective inhibitor of PI3Kβ inhibits the Akt/mTOR pathway in these tumors but not in those driven by receptor tyrosine kinases. However, inhibition of PI3Kβ only transiently inhibits Akt/mTOR signaling because it relieves feedback inhibition of IGF1R and other receptors and thus causes activation of PI3Kα and a rebound in downstream signaling. This rebound is suppressed and tumor growth inhibition enhanced with combined inhibition of PI3Kα and PI3Kβ. In PTEN-deficient models of prostate cancer, this effective inhibition of PI3K causes marked activation of androgen receptor activity. Combined inhibition of both PI3K isoforms and androgen receptor results in major tumor regressions., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Hyperactivation of the PI 3-kinase/AKT pathway is a driving force of many cancers. Here we identify the AKT-inactivating phosphatase PHLPP1 as a prostate tumor suppressor. We show that Phlpp1-loss causes neoplasia and, on partial Pten-loss, carcinoma in mouse prostate. This genetic setting initially triggers a growth suppressive response via p53 and the Phlpp2 ortholog, and reveals spontaneous Trp53 inactivation as a condition for full-blown disease. Surprisingly, the codeletion of PTEN and PHLPP1 in patient samples is highly restricted to metastatic disease and tightly correlated to deletion of TP53 and PHLPP2. These data establish a conceptual framework for progression of PTEN mutant prostate cancer to life-threatening disease., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Prostate cancer is characterized by its dependence on androgen receptor (AR) and frequent activation of PI3K signaling. We find that AR transcriptional output is decreased in human and murine tumors with PTEN deletion and that PI3K pathway inhibition activates AR signaling by relieving feedback inhibition of HER kinases. Similarly, AR inhibition activates AKT signaling by reducing levels of the AKT phosphatase PHLPP. Thus, these two oncogenic pathways cross-regulate each other by reciprocal feedback. Inhibition of one activates the other, thereby maintaining tumor cell survival. However, combined pharmacologic inhibition of PI3K and AR signaling caused near-complete prostate cancer regressions in a Pten-deficient murine prostate cancer model and in human prostate cancer xenografts, indicating that both pathways coordinately support survival., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Annotation of prostate cancer genomes provides a foundation for discoveries that can impact disease understanding and treatment. Concordant assessment of DNA copy number, mRNA expression, and focused exon resequencing in 218 prostate cancer tumors identified the nuclear receptor coactivator NCOA2 as an oncogene in approximately 11% of tumors. Additionally, the androgen-driven TMPRSS2-ERG fusion was associated with a previously unrecognized, prostate-specific deletion at chromosome 3p14 that implicates FOXP1, RYBP, and SHQ1 as potential cooperative tumor suppressors. DNA copy-number data from primary tumors revealed that copy-number alterations robustly define clusters of low- and high-risk disease beyond that achieved by Gleason score. The genomic and clinical outcome data from these patients are now made available as a public resource., (Copyright (c) 2010 Elsevier Inc. All rights reserved.)