Expression Of Estrogen Receptors In Type I And Type Ii Human Breast Epithelial Cells


A method is described for culturing morphologically and antigenically distinguishable types of normal human breast epithelial cells (HBEC) derived from reduction mammoplasty. Type I HBEC showed luminal and stem cell characteristics i.e. the ability to form budding/ductal structures when cultured on MATRIGEL and expressed a variant ER ( DIFFERENCE 48 Kd) which has a deletion in the DNA binding domain (exon 2). In contrast, Type II HBEC with basal epithelial phenotype are ER-negative when cultured on MATRIGEL. Simian virus 40 (SV40) transformed Type I and Type II HBEC lines also expressed the variant ER. Tumors formed in athymic nude mice by in vitro transformed tumorigenic Type I cell lines, however, expressed a high level of wild type ER which was undetectable in these cells grown in vitro before and after tumor formation. Thus, there appears to be a differentional ER mRNA splicing between the in vitro and in vivo milieu.

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Document History
  • Publication: Oct 31, 2000
  • Application: Jan 29, 1997
    US US 79065997 A
  • Priority: Jan 29, 1997
    US US 79065997 A
  • Priority: Nov 16, 1995
    US US 55878695 A
  • Priority: Sep 16, 1994
    US US 30811894 A

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