title: P53 but not cyclin E acts in a negative regulatory loop to control HER-2 expression in MCF-7 breast carcinoma cell line.
abstract: Cyclin E, HER-2 and p53, are considered as major prognostic markers in breast cancer. As they are related in patho-clinical level, we aimed to check if they have any direct interaction on expression of each other. To study the effect of cyclin E on HER-2 expression, cell lines stably overexpressing cyclin E or its low molecular weight (LMW) isoforms were generated. To understand the results of p53 silencing either alone or in combination with cyclin E overexpression, we created three different p53 stably knocked down cell lines. Protein expression was analyzed by western blot, HER-2 expression in the established cell lines were determined using SYBR green real time PCR and data analyzed by REST software. Results indicate that HER-2 expression is only downregulated following p53 silencing and none of cyclin E isoforms can alter its expression. The presence of cyclin E isoforms in p53 silenced clones also does not altered HER-2 expression. Given the fact that p53 degradation is increased by HER-2 overexpression, these data can draw a regulatory loop in which a non-mutated functional p53 and HER-2 can bidirectionally regulate the expression of these two genes. This study improves our understandings of these pathways and these proteins can be introduced either as a marker or as a target in cancer treatment.
authors.affiliation: Department of Molecular Biology, Pasteur Institute of Iran, Tehran, Iran. saeidbouzari@yahoo.com.
authors.forename: Hamed
authors.initials: H
authors.lastname: Montazeri
authors.forename: Saeid
authors.initials: S
authors.lastname: Bouzari
authors.forename: Kayhan
authors.initials: K
authors.lastname: Azadmanesh
authors.forename: Seyed Nasser
authors.initials: SN
authors.lastname: Ostad
authors.forename: Mohammad Hossein
authors.initials: MH
authors.lastname: Ghahremani
mesh_terms: D001483:Base Sequence; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D019927:Cyclin E / Q000502:physiology*; D017931:DNA Primers; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D020868:Gene Silencing; D006801:Humans; D061986:MCF-7 Cells; D016133:Polymerase Chain Reaction; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000502:physiology*
chemical_list: D019927:Cyclin E; D017931:DNA Primers; D018719:Erb-b2 Receptor Tyrosine Kinases; D016159:Tumor Suppressor Protein p53; C495901:TP53 protein, human