Selective Identification of Secreted and Transmembrane Breast Cancer Markers using Escherichia coli Ampicillin Secretion Trap

Abstract

Secreted and cell surface proteins play important roles in cancer and are potential drug targets and tumor markers. Here, we describe a large-scale analysis of the genes encoding secreted and cell surface proteins in breast cancer. To identify these genes, we developed a novel signal sequence trap method called Escherichia coli ampicillin secretion trap (CAST). For CAST, we constructed a plasmid in which the signal sequence of b-lactamase was deleted such that it does not confer ampicillin resistance. Eukaryotic cDNA libraries cloned into pCAST produced tens of thousands of ampicillinresistant clones, 80% of which contained cDNA fragments encoding secreted and membrane spanning proteins. We identified 2,708 unique sequences from cDNA libraries made from surgical breast cancer specimens. We analyzed the expression of 1,287 of the 2,708 genes and found that 166 were overexpressed in breast cancers relative to normal breast tissues. Eighty-five percent of these genes had not been previously identified as markers of breast cancer. Twenty-three of the 166 genes (14%) were relatively tissue restricted, suggesting use as cancer-specific targets. We also identified several new markers of ovarian cancer. Our results indicate that CAST is a robust, rapid, and low cost method to identify cell surface and secreted proteins and is applicable to a variety of relevant biological questions. (Cancer Res 2005; 65(18): 8209-17)

TSPAN8, identified by Escherichia coli ampicillin secretion trap, is associated with cell growth and invasion in gastric cancer

“…CAST is a signal sequence trap method that was developed by Ferguson et al [6]. Signal peptides, which typically consist of 4-15 hydrophobic amino acids flanked by a basic NH2 terminus and a polar COOH terminus, target secreted and transmembrane proteins in their appropriate subcellular location [7].…”

Oligophrenin-1 Is Associated with Cell Adhesion and Migration in Prostate Cancer

“…Genes encoding transmembrane/secretory proteins expressed specifically in cancers may be ideal biomarkers for cancer diagnosis, and may constitute a therapeutic target [2]. The Escherichia coli ampicillin secretion trap (CAST), a signal-sequence trap method developed by Ferguson et al [3], is a unique large-scale analysis method useful for identifying genes that encode transmembrane/secretory proteins. We previously generated CAST libraries from two PCa cell lines (LNCaP and DU145) and normal prostate, and identified several genes which were overexpressed in PCa cell lines [4,5].…”

Mucinous Cystadenocarcinoma: A Rare Variant of Breast Carcinoma: Case Report

“…1,6 Me tas ta tic mu ci no us carci no ma, par ti cu larly ori gi na ting from the ovary or pan cre as, sho uld be ru led out be fo re pri mary muci no us cyst ade no car ci noma of the bre ast is di agno sed. 7 Bre ast MCAs are CK 7 (+) and CK 20 (-) whi le both mar kers are po si ti ve in ova ri an and pan cre a tic mu ci no us ade no car ci no ma. In our ca se, CK 7 was po si ti ve and CK 20 was ne ga ti ve, and the ca re fuly exa mi na ti ons of the gas tro in tes ti nal and ge ni to u ri nary systems did not sho w any pri mary ma lig nan ci es.…”