The HER4 isoform JM-a/CYT2 relates to improved survival in bladder cancer patients but only if the estrogen receptor α is not expressed

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@article{f6fd11a559014a9e82d3018ee2fbc467,
title = "The HER4 isoform JM-a/CYT2 relates to improved survival in bladder cancer patients but only if the estrogen receptor α is not expressed",
abstract = "Bladder cancer tumors expressing human epidermal growth factor receptor 4 (HER4) demonstrate improved patient survival. HER4 isoforms and estrogen receptor alpha (ER-α) can form chaperone complexes causing cell-proliferation. We wanted to explore if HER4 isoforms and ER-α could correlate to poor prognosis in bladder cancers. We developed mRNA assays for HER4 isoforms (JM-a, JM-b, CYT1, and CYT2) and for ER-α. Expression was analyzed in tumors from 85 bladder cancer patients and compared to overall survival (median follow-up of 5.1 years). ER-α was expressed in 38{\%} (n = 32) of tumors but did not correlate to survival (p = 0.4698). HER4 was expressed in 42{\%} (n = 36) and in all cases as the ER-α binding isoform JM-a. The JM-a isoform can be alternatively spliced to either a CYT1 isoform (JM-a/CYT1) or a CYT2 isoform (JM-a/CYT2). All HER4 expressing tumors expressed the JM-a/CYT2 isoform and half of those (18/36) expressed both isoforms. JM-a/CYT2 expression correlated to improved survival (p = 0.004), but not when ER-α was co-expressed (p = 0.897). Immunohistochemistry revealed protein expression of HER4 and ER-α in tumor cells. Growth of RT4 bladder cancer cells, expressing both JM-a/CYT2 and ER-α was inhibited by the specific ER-α inhibitor raloxifene. Likewise, stable transfection with JM-a/CYT2 inhibited the growth of T24 bladder cancer cells, but only when ER-α was inhibited. Our results demonstrate that HER4 JM-a/CYT2 expressing bladder cancers relate to favorable prognosis when ER-α is not co-expressed. In vitro studies indicate that ER-α inhibition may be a useful treatment for patients with tumors expressing both ER-α and HER4 JM-a/CYT2.",
keywords = "Aged, Aged, 80 and over, Amino Acid Sequence, Carcinoma, Papillary/metabolism, Cell Line, Tumor, ErbB Receptors/metabolism, Estrogen Receptor alpha/metabolism, Female, Humans, Kaplan-Meier Estimate, Male, Middle Aged, Molecular Sequence Data, Protein Isoforms/metabolism, Receptor, ErbB-4, Urinary Bladder Neoplasms/metabolism",
author = "Mathias Munk and Ashfaque Memon and Poulsen, {Steen S} and Michael Borre and Ebba Nexo and Sorensen, {Boe S}",
year = "2013",
month = "9",
doi = "10.3109/00365513.2013.818706",
language = "English",
volume = "73",
pages = "503--13",
journal = "Scandinavian Journal of Clinical & Laboratory Investigation",
issn = "1502-7686",
publisher = "Informa Healthcare",
number = "6",

}