title: Breast cancer tissue slices as a model for evaluation of response to rapamycin.
abstract: Rapamycin is a selective inhibitor of the mammalian target of rapamycin (mTOR), a regulator kinase that integrates growth factors signaling via the phosphoinositide-3-kinase pathway and that has emerged as a novel therapeutic modality in breast cancer (BC). We propose a pre-clinical "ex-vivo" personalized organotypic culture of BC that preserves the microenvironment to evaluate rapamycin-mediated gene expression changes. Freshly excised ductal invasive BC slices, 400 μm thick (n=30), were cultured in the presence or absence (control) of rapamycin (20 nM) for 24 h. Some slices were formalin-fixed for immunohistochemical determinations and some were processed for microarray analysis. Control slices in culture retained their tissue morphology and tissue viability (detected by BrdU uptake). The percentage of proliferating cells (assessed by Ki67) did not change up to 24 h of treatment. Immunohistochemical evaluation of p-AKT, p-mTOR, p-4EBP1 and p-S6K1 indicated that AKT/mTOR pathway activation was maintained during cultivation. For microarray analysis, slices were divided into two groups, according to the presence/absence of epidermal growth factor receptor-type 2 and analyzed separately. Limited overlap was seen among differentially expressed genes after treatment (P<0.01) in both groups suggesting different responses to rapamycin between these BC subtypes. Ontology analysis indicated that genes involved in biosynthetic processes were commonly reduced by rapamycin. Our network analysis suggested that concerted expression of these genes might distinguish controls from treated slices. Thus, breast carcinoma slices constitute a suitable physiological tool to evaluate the short-term effects of rapamycin on the gene profile of individual BC samples.
authors: Instituto Brasileiro de Controle do Câncer, Av. Alcântara Machado 2576, CEP 03102-002, São Paulo, SP, Brasil.
authors: Stana Helena Giorgi
authors: SH
authors: Grosso
authors: Maria Lucia Hirata
authors: ML
authors: Katayama
authors: Rosimeire Aparecida
authors: RA
authors: Roela
authors: Suely
authors: S
authors: Nonogaki
authors: Fernando Augusto
authors: FA
authors: Soares
authors: Helena
authors: H
authors: Brentani
authors: Leandro
authors: L
authors: Lima
authors: Maria Aparecida Azevedo Koike
authors: MA
authors: Folgueira
authors: Angela Flávia Logullo
authors: AF
authors: Waitzberg
authors: Fátima Solange
authors: FS
authors: Pasini
authors: João Carlos Guedes Sampaio
authors: JC
authors: Góes
authors: M Mitzi
authors: MM
authors: Brentani
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D053263:Gene Regulatory Networks / Q000187:drug effects; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000378:metabolism; D008875:Middle Aged; D008954:Models, Biological; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology / Q000627:therapeutic use*; D046509:Tissue Culture Techniques
chemical_list: D019394:Ki-67 Antigen; D009363:Neoplasm Proteins; D010750:Phosphoproteins; D018719:Erb-b2 Receptor Tyrosine Kinases; D020123:Sirolimus; C508053:ERBB2 protein, human