Androgen receptor functions as transcriptional repressor of cancer-associated fibroblast activation
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
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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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 7

HDFs with reduced AR expression favor SCC cell growth in vivo.

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HDFs with reduced AR expression favor SCC cell growth in vivo. (A) EGFP-...
(A) EGFP-expressing SCC13 cells were admixed with 2 different HDF strains with silenced AR versus control, followed by parallel injections into contralateral ears of NOD/SCID/IL2rg–/– mice (8–10 weeks old, females). Left: Representative images of combined bright-field and fluorescence microscopy of 1 pair of mouse ear lesions, at 21 days after injection. Scale bar: 1 mm. Right: Quantification of tumor volumes (V = length × width × 0.5) formed in the presence of HDFs with silenced AR versus control. Data are represented as mean ± SD. n(tumor pairs) = 9; ***P < 0.005, 2-tailed paired t test. (B) Immunofluorescence analysis and quantification of Ki67- and keratin-positive cells in lesions formed by SCC13 cells admixed with HDFs with or without AR silencing. Shown are representative images and quantification for 3 ear pairs, examining at least 4 independent fields per lesion, using ImageJ software for determination of Ki67/keratin–double-positive cells. Scale bar: 30 μm. Data are represented as mean ± SD. n(tumor pairs) = 3; *P < 0.05, 2-tailed paired t test. (C–F) Immunofluorescence analysis and quantification of the indicated markers in lesions formed by SCC13 cells admixed with HDFs with or without AR silencing. Shown are representative images and quantification for 3 ear pairs, examining at least 4 independent fields per lesion, using ImageJ software. Scale bars: 60 μm. Values are expressed as percentage of surface area positive for the indicated markers. Data are represented as mean ± SD. n(tumor pairs) = 3; *P < 0.05, ***P < 0.005, 2-tailed unpaired t test. Additional data for p53, macrophage, and angiogenesis markers and further in vivo experiment with CAL27 SCC cells are shown in Supplemental Figures 4 and 5.