Research Article

Intracellular Signaling Pathways Regulate Hormone-Dependent Kallikrein Gene Expression
Miltiadis Paliouras^{a, b}, Eleftherios P. Diamandis<sup>a, b

a</sup>Department of Laboratory Medicine and Pathobiology, University of Toronto and
^bSamuel Lunenfeld Research Institute and Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Ont., Canada

Address of Corresponding Author

Tumor Biol 2008;29:63-75 (DOI: 10.1159/000135686)

  Key Words

• Kallikreins
• Breast cancer
• Gene expression
• Intracellular signaling pathways
• Steroid hormones
• Chemical inhibitors, hormone-dependent expression
• Transcription factors
• Androgen receptor

  Abstract

Objectives: Our aim was to examine how certain signal transduction pathways influence the regulation of hormone-dependent kallikrein (KLK) gene expression in androgen-sensitive breast cancer cell lines. Methods: We used the breast cancer cell lines T47D and BT474, treated with steroid hormones or various pathway inhibitors. KLKs were quantified by ELISA. RT-PCR, Western blots and immunoprecipitations were used to assess transcript and protein levels. Results:PSA, KLK10, KLK11, KLK13 and KLK14 are upregulated upon androgen stimulation in the T47D cell line. The expression of PSA, KLK10 and KLK11 was repressed by the MEK1/2 inhibitor U0126 and the PI3K inhibitor Wortmannin in the presence of the hormone, thus implicating the RAS/MEK/ERK and PI3K/AKT signaling pathways in regulating hormone-dependent KLK gene activation. Analysis of inhibitor-treated cells revealed changes in c-MYC expression with a pattern parallel to KLK gene expression. Chromatin immunoprecipitations identified androgen-dependent recruitment of specific transcription factors to the KLK proximal promoters, including c-MYC binding to PSA and KLK11. Conclusion: The hormone-specific upregulation of PSA, KLK10 and KLK11 in the breast cancer cell line T47D is dependent on major intracellular signaling pathways. This work provides a new dimension to the regulation of these cancer-related genes and the potential for new therapeutic targeting strategies.

Copyright © 2008 S. Karger AG, Basel

  Author Contacts

Eleftherios P. Diamandis, MD, PhD, FRCPC
Department of Pathology and Laboratory Medicine, Mount Sinai Hospital
6th Floor, 60 Murray Street
Toronto, Ont. M5T 3L9 (Canada)
Tel. +1 416 586 8443, Fax +1 416 586 8628, E-Mail ediamandis@mtsinai.on.ca

  Article Information

Received: December 2, 2007
Accepted after revision: March 17, 2008
Published online: June 2, 2008
Number of Print Pages : 13
Number of Figures : 6, Number of Tables : 0, Number of References : 48