Androgen receptor functions as transcriptional repressor of cancer-associated fibroblast activation
Andrea Clocchiatti, … , Berna C. Özdemir, G. Paolo Dotto
Andrea Clocchiatti, … , Berna C. Özdemir, G. Paolo Dotto
Published November 5, 2018
Citation Information: J Clin Invest. 2018;128(12):5531-5548. https://doi.org/10.1172/JCI99159.
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Research Article Dermatology Oncology

Androgen receptor functions as transcriptional repressor of cancer-associated fibroblast activation

Abstract

The aging-associated increase of cancer risk is linked with stromal fibroblast senescence and concomitant cancer-associated fibroblast (CAF) activation. Surprisingly little is known about the role of androgen receptor (AR) signaling in this context. We have found downmodulated AR expression in dermal fibroblasts underlying premalignant skin cancer lesions (actinic keratoses and dysplastic nevi) as well as in CAFs from the 3 major skin cancer types, squamous cell carcinomas (SCCs), basal cell carcinomas, and melanomas. Functionally, decreased AR expression in primary human dermal fibroblasts (HDFs) from multiple individuals induced early steps of CAF activation, and in an orthotopic skin cancer model, AR loss in HDFs enhanced tumorigenicity of SCC and melanoma cells. Forming a complex, AR converged with CSL/RBP-Jκ in transcriptional repression of key CAF effector genes. AR and CSL were positive determinants of each other’s expression, with BET inhibitors, which counteract the effects of decreased CSL, restoring AR expression and activity in CAFs. Increased AR expression in these cells overcame the consequences of CSL loss and was by itself sufficient to block the growth and tumor-enhancing effects of CAFs on neighboring cancer cells. As such, the findings establish AR as a target for stroma-focused cancer chemoprevention and treatment.

Authors

Andrea Clocchiatti, Soumitra Ghosh, Maria-Giuseppina Procopio, Luigi Mazzeo, Pino Bordignon, Paola Ostano, Sandro Goruppi, Giulia Bottoni, Atul Katarkar, Mitchell Levesque, Peter Kölblinger, Reinhard Dummer, Victor Neel, Berna C. Özdemir, G. Paolo Dotto

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Figure 5

AR gene silencing in HDFs reduces proliferation and induces senescence.

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AR gene silencing in HDFs reduces proliferation and induces senescence....
(A) Growth curve of 3 HDF strains with AR-silencing lentiviruses (sh AR1, AR2) versus control vector (sh CT). An equal number of cells were plated onto dishes 9 days after lentiviral infection and antibiotic resistance selection, followed by cell number determination at the indicated times (days) after plating. Data are expressed as mean values of the 3 strains ± SD. n(HDF strains) = 3; ***P < 0.005, 1-way ANOVA with Dunnett’s test. (B) Left: EdU labeling assays of 3 HDF strains 10 days after infection with AR-silencing lentiviruses (sh AR1, AR2) versus control vector (sh CT). Right: Senescence-associated β-galactosidase staining of 3 HDF strains with AR-silencing lentiviruses (sh AR1, AR2) versus control vector (sh CT) 10 days after lentiviral vector infection. At least 200 cells per condition were scored. Values for each strain are indicated with mean ± SD. n(HDF strains) = 3; **P < 0.01,***P < 0.005, 1-way ANOVA with Dunnett’s test. (C) Immunoblot analysis of 2 HDF strains infected with AR-silencing lentiviruses (sh AR1, AR2) versus control vector (sh CT), with antibodies against the indicated proteins. Blots were sequentially probed with antibodies against phospho-Ser795 RB, phospho–Ser780 RB, phospho-H3, RB, and γ-tubulin. A separate membrane was probed with antibodies against PCNA and β-actin. (D) RT-qPCR analysis of the indicated genes in 3 HDF strains infected with AR-silencing lentiviruses (sh AR1, AR2) versus control vector (sh CT). Values for each strain are indicated with mean ± SD. n(HDF strains) = 3; *P < 0.05, **P < 0.01, ***P < 0.005, 1-way ANOVA with Dunnett’s test.