Send to

Choose Destination
See comment in PubMed Commons below
Breast Cancer Res Treat. 2007 Oct;105(2):139-55. Epub 2007 Feb 13.

Unmasking of epigenetically silenced genes reveals DNA promoter methylation and reduced expression of PTCH in breast cancer.

Author information

  • 1Division of Hematology/Oncology, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, CA, USA.


A pharmacological-based global screen for epigenetically silenced tumor suppressor genes was performed in MCF-7 and MDA-MB-231 breast cancer cells. Eighty-one genes in MCF-7 cells and 131 in MDA-MB-231 cells were identified, that had low basal expression and were significantly upregulated following treatment. Eighteen genes were studied for methylation and/or expression in breast cancer; PTCH, the receptor for the hedgehog (Hh) pathway and a known tumor suppressor gene, was selected for further analysis. Methylation of the PTCH promoter was found in MCF-7 cells and in breast cancer samples, and correlated with low PTCH expression. Immunohistochemical analysis of breast tissue arrays revealed high expression of PTCH in normal breast compared to ductal carcinomas in situ (DCIS) and invasive ductal carcinomas; furthermore, association was found between PTCH expression and favorable prognostic factors. PTCH is an inhibitor of the Hh pathway, and its silencing activates the pathway and promotes growth. Indeed, high activity of the Hh pathway was identified in MCF-7 cells and overexpression of PTCH inhibited the pathway. Moreover, treatment with cyclopamine, an inhibitor of the pathway, reduced cell growth and slowed the cell cycle in these cells. Thus, unmasking of epigenetic silencing in breast cancer enabled us to discover a large number of candidate tumor suppressor genes. Further analysis suggested a role of one of these genes, PTCH, in breast cancer tumorigenesis.

[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Springer
    Loading ...
    Support Center