title: Expression of two novel eph-related receptor protein tyrosine kinases in mammary gland development and carcinogenesis.
abstract: To investigate the involvement of protein tyrosine kinases (PTKs) in the growth control of mammary epithelial cells, we have used PCR based cloning to identify PTKs expressed in a mouse mammary epithelial cell line. This approach led to the isolation of two receptor PTKs of the eph-related subfamily; myk-1, a novel member expressed predominantly in lung, heart and mammary gland and myk-2, a close relative of the human eck gene. Northern blot analysis of RNA from mouse mammary glands at different stages of development revealed that myk-1 and myk-2 expression is induced at puberty and differentially regulated during the estrus cycle. myk-1 and myk-2 expression was down-regulated during the pregnancy induced differentiation of the mammary gland. Over-expression of myk-1 and myk-2 was found in the undifferentiated and invasive mammary tumors of transgenic mice expressing the Ha-ras oncogene. In contrast, no elevated expression of either gene could be detected in the well differentiated and non-metastatic mammary tumors of c-myc expressing transgenic mice. These results indicate that myk-1 and myk-2 expression is induced during the proliferation of the mammary gland and down-regulated by its differentiation.
authors.affiliation: Laboratory for Clinical and Experimental Research, University of Bern, Switzerland.
authors.forename: A C
authors.initials: AC
authors.lastname: Andres
authors.forename: H H
authors.initials: HH
authors.lastname: Reid
authors.forename: G
authors.initials: G
authors.lastname: Zürcher
authors.forename: R J
authors.initials: RJ
authors.lastname: Blaschke
authors.forename: D
authors.initials: D
authors.lastname: Albrecht
authors.forename: A
authors.initials: A
authors.lastname: Ziemiecki
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D008321:Mammary Glands, Animal / Q000737:chemistry*; D015674:Mammary Neoplasms, Animal / Q000737:chemistry*; D051379:Mice; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000737:chemistry* / Q000235:genetics; D011505:Protein-Tyrosine Kinases / Q000737:chemistry* / Q000235:genetics; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry* / Q000235:genetics; D036104:Receptor, EphA2; D036224:Receptor, EphB4; D014407:Tumor Cells, Cultured
chemical_list: D009363:Neoplasm Proteins; C086681:Ephb4 protein, mouse; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; D036104:Receptor, EphA2; D036224:Receptor, EphB4