Microarrays Research Today is a free monthly online journal that collates and summarizes the latest research about Microarrays, including details on experiments, designs, statistics, analysis, software.

The needle in the haystack: application of breast fine-needle aspirate samples to quantitative protein microarray technology.

Rapkiewicz A, Espina V, Zujewski JA, Lebowitz PF, Filie A, Wulfkuhle J, Camphausen K, Petricoin EF, Liotta LA, Abati A

Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA. rapkia01@med.nyu.edu

BACKGROUND: There is an unmet clinical need for economic, minimally invasive procedures that use a limited number of cells for the molecular profiling of tumors in individual patients. Reverse-phase protein microarray (RPPM) technology has been applied successfully to the quantitative analysis of breast, ovarian, prostate, and colorectal cancers using frozen surgical specimens. METHODS: For this report, the authors investigated the novel use of RPPM technology for the analysis of both archival cytology aspirate smears and frozen fine-needle aspiration (FNA) samples. RPPMs were printed with 63 breast FNA samples that were obtained before, during, and after treatment from 21 patients who were enrolled in a Phase II trial of neoadjuvant capecitabine and docetaxel therapy for breast cancer. RESULTS: Based on an MCF7 cell line model of breast adenocarcinoma, the sensitivity of the RPPM detection method was in the femtomolar range with a coefficient of variance <13.5% for the most dilute sample. Assay linearity was noted from 1.0 microg/microL to 7.8 ng/microL total protein/array spot (R(2) = 0.9887) for a membrane receptor protein (epidermal growth factor receptor; R(2) = 0.9935). CONCLUSIONS: The results from this study indicated that low-abundance analytes and phosphorylated and nonphosphorylated proteins in specimens that consist of a few thousand cells obtained through FNA can be quantified with RPPM technology. The ability to monitor the in vivo state of cell-signaling proteins before and after treatment potentially will augment the ability to design individualized therapy regimens through the mapping of aberrant cell-signaling phenotypes. The mapping of these protein pathways will further the development of rational drug targets.

Published 18 June 2007 in Cancer, 111(3): 173-84.
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