VSGP/F-spondin: a new ovarian cancer marker.

The discovery of genes that are overexpressed in ovarian cancers provides valuable insight into ovarian cancer biology and will lead to the development of more effective treatment strategies for combating this disease. To identify genes exhibiting ovarian- and ovarian cancer-specific expression, we generated four subtracted cDNA libraries from primary and metastatic ovarian adenocarcinoma tissues. 3,400 cDNA clones from these libraries were analyzed by microarray for tissue distribution and tumor specificity using 32 pairs of fluorophore-labeled cDNA samples from a variety of normal tissues and ovarian tumor tissues. cDNA clones showing elevated expression in ovarian tumors were identified by DNA sequencing with comparison to public databases, and the most promising candidates were further analyzed by quantitative real-time polymerase chain reaction and Northern blot. This systematic approach led to the identification of a number of genes including vascular smooth muscle growth-promoting factor (VSGP/F-spondin), a secreted protein previously identified and cloned from bovine and human ovary. VSGP/F-spondin protein was observed in ovarian carcinomas but not in normal ovarian epithelium by immunohistochemistry with a VSGP/F-spondin antibody. The expression profile of VSGP/F-spondin identifies this molecule as a potential diagnostic marker or target for developing therapeutic strategies to treat ovarian carcinoma.

Serum antibodies to lipophilin B detected in late stage breast cancer patients.

Lipophilin B mRNA is overexpressed in approximately 70% of breast tumors and shows a high degree of correlation with the mRNA expression profile of mammaglobin. This is further supported by the recent finding that, like other members of the secretoglobulin-uteroglobin family, mammaglobin and lipophilin B form a heteroduplex. The studies described show that there are pre-existing antibodies to lipophilin B peptide in the sera of breast cancer patients with different stages and grade of tumor and that this response is different from that seen to recombinant mammaglobin and native mammaglobin-lipophilin B complex. The highest titers were observed in later stage tumors. In addition, low levels of antibody were also seen in some patients with prostate and ovarian cancers, consistent with lipophilin B mRNA expression in these tumors at lower abundance than in breast tumors. In contrast, lipophilin B antibodies were absent in 20 healthy donor sera and 30 lung cancer sera. A polymorphism identified in Lipophilin B did not appear to influence human sera reactivity. The data indicate that humoral immune responses to lipophilin B may serve as a diagnostic indicator, particularly for breast cancer.

Application of a multigene reverse transcription-PCR assay for detection of mammaglobin and complementary transcribed genes in breast cancer lymph nodes.

BACKGROUND: Mammaglobin mRNA expression is found in 70-80% of primary and metastatic breast tumor biopsies. The potential breast tumor markers B305D, B726P, and gamma-aminobutyrate type A receptor pi subunit (GABApi) complement the expression of mammaglobin. Collectively the expression profile of these four genes could be used as a diagnostic and prognostic indicator for breast cancer. METHODS: A multigene reverse transcription-PCR (RT-PCR) assay was established to detect the expression of mammaglobin, GABApi, B305D, and B726P simultaneously. Specific primers and TaqMan probes were used to analyze combined mRNA expression profiles in primary breast tumors and metastatic lymph node specimens. RESULTS: The multigene RT-PCR assay detected substantial expression signals in 27 of 27 primary tumor and 50 of 50 metastatic breast lymph node samples. Specificity studies demonstrated no significant expression signal in 27 non-breast cancer lymph nodes, in 22 various healthy tissue samples, or in 14 colon tumor samples. CONCLUSION: The novel RT-PCR-based assay described here provides a sensitive detection system for disseminated breast tumor cells in lymph nodes. In addition, this multigene assay could also be used to test peripheral blood and bone marrow samples.

Discovery of differentially expressed genes in human breast cancer using subtracted cDNA libraries and cDNA microarrays.

Identifying novel and known genes that are differentially expressed in breast cancer has important implications in understanding the biology of breast tumorigenesis and developing new diagnostic and therapeutic agents. In this study we have combined two powerful technologies, PCR-based cDNA subtraction and cDNA microarray, as a high throughput methodology designed to identify cDNA clones that are breast tumor- and tissue-specific and are overexpressed in breast tumors. Approximately 2000 cDNA clones generated from the subtracted breast tumor library were arrayed on the microarray chips. The arrayed target cDNAs were then hybridized with 30 pairs of fluorescent-labeled cDNA probes generated from breast tumors and normal tissues to determine the tissue distribution and tumor specificity. cDNA clones showing overexpression in breast tumors by microarray were further analysed by DNA sequencing, GenBank and EST database searches, and quantitative real time PCR. We identified several known genes, including mammaglobin, cytokeratin 19, fibronectin, and hair-specific type II keratin, which have previously been shown to be overexpressed in breast tumors and may play an important role in the malignance of breast. We also discovered B726P which appears to be an isoform of NY-BR-1, a breast tissue-specific gene. Two additional clones discovered, B709P and GABA(A) receptor pi subunit, were not previously described for their overexpression profile in breast tumors. Thus, combining PCR-based cDNA subtraction and cDNA microarray allowed for an efficient way to identify and validate genes with elevated mRNA expression levels in breast cancer that may potentially be involved in breast cancer progression. These differentially expressed genes may be of potential utility as therapeutic and diagnostic targets for breast cancer.