title: Tumor slices as a model to evaluate doxorubicin in vitro treatment and expression of trios of genes PRSS11, MTSS1, CLPTM1 and PRSS11, MTSS1, SMYD2 in canine mammary gland cancer.
abstract: BACKGROUND
  In women with breast cancer submitted to neoadjuvant chemotherapy based in doxorubicin, tumor expression of groups of three genes (PRSS11, MTSS1, CLPTM1 and PRSS11, MTSS1, SMYD2) have classified them as responsive or resistant. We have investigated whether expression of these trios of genes could predict mammary carcinoma response in dogs and whether tumor slices, which maintain epithelial-mesenchymal interactions, could be used to evaluate drug response in vitro.
  
  
  METHODS
  Tumors from 38 dogs were sliced and cultured with or without doxorubicin 1 muM for 24 h. Tumor cells were counted by two observers to establish a percentage variation in cell number, between slices. Based on these results, a reduction in cell number between treated and control samples > or = 21.7%, arbitrarily classified samples, as drug responsive. Tumor expression of PRSS11, MTSS1, CLPTM1 and SMYD2, was evaluated by real time PCR. Relative expression results were then transformed to their natural logarithm values, which were spatially disposed according to the expression of trios of genes, comprising PRSS11, MTSS1, CLPTM1 and PRSS11, MTSS1, SMYD2. Fisher linear discrimination test was used to generate a separation plane between responsive and non-responsive tumors.
  
  
  RESULTS
  Culture of tumor slices for 24 h was feasible. Nine samples were considered responsive and 29 non-responsive to doxorubicin, considering the pre-established cut-off value of cell number reduction > or = 21.7%, between doxorubicin treated and control samples. Relative gene expression was evaluated and tumor samples were then spatially distributed according to the expression of the trios of genes: PRSS11, MTSS1, CLPTM1 and PRSS11, MTSS1, SMYD2. A separation plane was generated. However, no clear separation between responsive and non-responsive samples could be observed.
  
  
  CONCLUSIONS
  Three-dimensional distribution of samples according to the expression of the trios of genes PRSS11, MTSS1, CLPTM1 and PRSS11, MTSS1, SMYD2 could not predict doxorubicin in vitro responsiveness. Short term culture of mammary gland cancer slices may be an interesting model to evaluate chemotherapy activity.
authors.affiliation: Departamento de Radiologia e Cancerologia, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brasil. renasobral@hotmail.com
authors.forename: Renata A
authors.initials: RA
authors.lastname: Sobral
authors.forename: Suzana T
authors.initials: ST
authors.lastname: Honda
authors.forename: Maria Lucia H
authors.initials: ML
authors.lastname: Katayama
authors.forename: Helena
authors.initials: H
authors.lastname: Brentani
authors.forename: M Mitzi
authors.initials: MM
authors.lastname: Brentani
authors.forename: Diogo F C
authors.initials: DF
authors.lastname: Patrão
authors.forename: Maria Aparecida A K
authors.initials: MA
authors.lastname: Folgueira
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000627:therapeutic use*; D004283:Dog Diseases / Q000188:drug therapy* / Q000235:genetics; D004285:Dogs; D004317:Doxorubicin / Q000627:therapeutic use*; D005260:Female; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D015674:Mammary Neoplasms, Animal / Q000188:drug therapy* / Q000235:genetics
chemical_list: D000903:Antibiotics, Antineoplastic; D004317:Doxorubicin