Intracellular signaling pathways regulate hormone-dependent kallikrein gene expression.
OBJECTIVE
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.


CONCLUSIONS
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.
Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ont., Canada.
Miltiadis
M
Paliouras
Eleftherios P
EP
Diamandis
D000728:Androgens / Q000378:metabolism*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D006801:Humans; D007610:Kallikreins / Q000235:genetics / Q000378:metabolism*; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000037:antagonists & inhibitors; D051058:Oncogene Protein v-akt / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017430:Prostate-Specific Antigen / Q000235:genetics / Q000378:metabolism; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D011944:Receptors, Androgen / Q000378:metabolism; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D012717:Sesquiterpenes / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology*; D015533:Transcriptional Activation
D000728:Androgens; D000894:Anti-Inflammatory Agents, Non-Steroidal; C489427:MYC protein, human; D016328:NF-kappa B; D016271:Proto-Oncogene Proteins c-myc; D011944:Receptors, Androgen; D012717:Sesquiterpenes; C114880:trypsin-like serine protease; C002669:parthenolide; D019869:Phosphatidylinositol 3-Kinases; D051058:Oncogene Protein v-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D020930:MAP Kinase Kinase Kinases; C100936:KLK10 protein, human; D007610:Kallikreins; D012697:Serine Endopeptidases; D017430:Prostate-Specific Antigen