title: An innovative microarray strategy identities informative molecular markers for the detection of micrometastatic breast cancer.
abstract: There is increasing evidence that molecular detection of micrometastatic breast cancer in the axillary lymph nodes (ALN) of breast cancer patients can improve staging. Molecular analyses of samples obtained from the Minimally Invasive Molecular Staging of Breast Cancer Trial (n = 489 patients) indicate that whereas the majority of molecular markers are informative for the detection of metastatic breast cancer (significant disease burden), only a few are sensitive for the detection of micrometastatic disease (limited disease burden). Frequency distribution and linear regression analyses reveal that relative levels of gene expression are highly correlated with apparent sensitivity for the detection of micrometastic breast cancer (P < 0.05). These data provides statistical validation of the concept that the most informative markers for detection of micrometastatic disease are those that are most highly expressed in metastatic disease. To test this hypothesis, we developed an innovative microarray strategy. RNA from a metastatic breast cancer ALN was diluted into RNA from a normal lymph node and analyzed using Affymetrix microarrays. Expression analysis indicated that only two genes [mammaglobin (mam) and trefoil factor 1 (TFF1)] were significantly overexpressed at a dilution of 1:50. Real-time reverse transcription-PCR analysis of pathology-negative ALN (n = 72) confirm that of all the markers tested, mam and TFF1 have the highest apparent sensitivity for detection of micrometastatic breast cancer. We conclude that a dilutional microarray approach is a simple and reliable method for the identification of informative molecular markers for the detection of micrometastatic cancer.
authors.affiliation: Department of Surgery, College of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA. mikhitar@musc.edu
authors.forename: Kaidi
authors.initials: K
authors.lastname: Mikhitarian
authors.forename: William E
authors.initials: WE
authors.lastname: Gillanders
authors.forename: Jonas S
authors.initials: JS
authors.lastname: Almeida
authors.forename: Renee
authors.initials: R
authors.lastname: Hebert Martin
authors.forename: Juan C
authors.initials: JC
authors.lastname: Varela
authors.forename: John S
authors.initials: JS
authors.lastname: Metcalf
authors.forename: David J
authors.initials: DJ
authors.lastname: Cole
authors.forename: Michael
authors.initials: M
authors.lastname: Mitas
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology*; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D008207:Lymphatic Metastasis / Q000175:diagnosis / Q000235:genetics; D060785:Mammaglobin A; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics; D009367:Neoplasm Staging / Q000379:methods; D020411:Oligonucleotide Array Sequence Analysis; D011506:Proteins / Q000235:genetics; D012044:Regression Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D000071163:Trefoil Factor-1; D025521:Tumor Suppressor Proteins; D014598:Uteroglobin / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D060785:Mammaglobin A; D009363:Neoplasm Proteins; D011506:Proteins; C556448:SCGB2A2 protein, human; C051838:TFF1 protein, human; D000071163:Trefoil Factor-1; D025521:Tumor Suppressor Proteins; D014598:Uteroglobin