Castration resistance in human prostate cancer is conferred by a frequently occurring androgen receptor splice variant
Shihua Sun, … , Peter S. Nelson, Stephen R. Plymate
Shihua Sun, … , Peter S. Nelson, Stephen R. Plymate
Published July 19, 2010
Citation Information: J Clin Invest. 2010;120(8):2715-2730. https://doi.org/10.1172/JCI41824.
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Research Article Oncology

Castration resistance in human prostate cancer is conferred by a frequently occurring androgen receptor splice variant

Abstract

Progression of prostate cancer following castration is associated with increased androgen receptor (AR) expression and signaling despite AR blockade. Recent studies suggest that these activities are due to the generation of constitutively active AR splice variants, but the mechanisms by which these splice variants could mediate such effects are not fully understood. Here we have identified what we believe to be a novel human AR splice variant in which exons 5, 6, and 7 are deleted (ARv567es) and demonstrated that this variant can contribute to cancer progression in human prostate cancer xenograft models in mice following castration. We determined that, in human prostate cancer cell lines, ARv567es functioned as a constitutively active receptor, increased expression of full-length AR (ARfl), and enhanced the transcriptional activity of AR. In human xenografts, human prostate cancer cells transfected with ARv567es cDNA formed tumors that were resistant to castration. Furthermore, the ratio of ARv567es to ARfl expression within the xenografts positively correlated with resistance to castration. Importantly, we also detected ARv567es frequently in human prostate cancer metastases. In summary, these data indicate that constitutively active AR splice variants can contribute to the development of castration-resistant prostate cancers and may serve as biomarkers for patients who are likely to suffer from early recurrence and are candidates for therapies directly targeting the AR rather than ligand.

Authors

Shihua Sun, Cynthia C.T. Sprenger, Robert L. Vessella, Kathleen Haugk, Kathryn Soriano, Elahe A. Mostaghel, Stephanie T. Page, Ilsa M. Coleman, Holly M. Nguyen, Huiying Sun, Peter S. Nelson, Stephen R. Plymate

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Figure 6

The splice variant ARv567es forms a complex with ARfl.

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The splice variant ARv567es forms a complex with ARfl. (A) Immunopre...
(A) Immunoprecipitate with an HA antibody in M12 cells double transfected with ARfl and HA-ARv567es, followed by immunoblotting with AR C-19, which only recognizes ARfl, and AR sc441, which recognizes both ARv567es and ARfl. As a positive control, Flag-tagged ARfl was transfected into M12 cells and brought down with a Flag antibody. Lanes were run on same gel but were noncontiguous. (B) M12 cells transfected with the ARfl construct alone or in combination with the HA-ARv567es construct. Cells were grown in serum-free media and then treated with DHT 10-9 M or vehicle (EtOH). ARfl was immunolabeled with the AR C-19 antibody (red) and nuclei were immunolabeled with DAPI (blue). In cells containing both ARfl and ARv567es, ARfl translocates to the nucleus in the absence of ligand. Scale bar: 10 μm. (C) Relative quantitative nuclear translocation of ARfl. A minimum of 100 AR-positive cells were included for each construct. For comparisons, the population with the lowest percentage of translocation was considered 0 (ARfl with no DHT), and the population with the highest percentage of translocation was considered 1 (ARv567es with DHT). Values are mean ± SEM. **P < 0.001, ***P < 0.0001, compared with ARfl with same treatment. (D) Tumor lysates were made from LuCaP 35 and 136 xenografts taken from castrated SCID mice, immunoprecipitated with AR C-19, and immunoblotted with AR sc441. ARv567es was brought down with ARfl in the LuCaP 136 xenograft.