title: Overexpression of MDM2 oncoprotein correlates with possession of estrogen receptor alpha and lack of MDM2 mRNA splice variants in human breast cancer.
abstract: To evaluate the significance of murine double minute 2 (MDM2) oncoprotein in human breast cancer as a nuclear-cytoplasmic shuttling protein, an estrogen receptor (ER) alpha regulator, and a prognostic marker and to study how MDM2 is overexpressed, we investigated its status in tissue samples and examined the correlation between overexpression and MDM2 gene abnormalities, status, and clinicopathological parameters. We detected MDM2 oncoprotein in both nucleus and cytoplasm by frozen-section immunohistochemistry. There was a significant correlation between MDM2 overexpression and low-grade nuclear atypia, absence of lymph node involvement, and increased levels of ER alpha protein. Our molecular assays found no point mutations in Ser17, but there was a correlation between MDM2 overexpression and the lack of splice variant mRNAs. These results suggest that the distribution of MDM2 reflects its nuclear-cytoplasmic shuttling ability; that interaction between p53 and MDM2 for tumor progression is not enhanced by point mutations at codon 17; and that the expression of MDM2 splice variants is a reason for the lack of its overexpression. MDM2 overexpression correlates with favorable prognostic parameters. A decreased level of MDM2 will lead to a deviation from the ER alpha signaling pathway.
authors.affiliation: Department of Pathology, Ibaraki Prefectural Central Hospital and Cancer Center, Japan. ms-hori@chubyoin.pref.ibaraki.jp
authors.forename: Masao
authors.initials: M
authors.lastname: Hori
authors.forename: Jiro
authors.initials: J
authors.lastname: Shimazaki
authors.forename: Satoshi
authors.initials: S
authors.lastname: Inagawa
authors.forename: Masayuki
authors.initials: M
authors.lastname: Itabashi
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Hori
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000235:genetics* / Q000473:pathology; D002467:Cell Nucleus / Q000737:chemistry; D003062:Codon / Q000235:genetics; D003593:Cytoplasm / Q000737:chemistry; D018450:Disease Progression; D047628:Estrogen Receptor alpha; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008207:Lymphatic Metastasis; D009687:Nuclear Proteins; D017354:Point Mutation; D011379:Prognosis; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis* / Q000235:genetics; D051736:Proto-Oncogene Proteins c-mdm2; D012333:RNA, Messenger / Q000235:genetics*; D011960:Receptors, Estrogen / Q000096:biosynthesis* / Q000502:physiology; D015398:Signal Transduction
chemical_list: D003062:Codon; D047628:Estrogen Receptor alpha; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D011960:Receptors, Estrogen; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2