Fletcher GC et al. (2003), hAG-2 and hAG-3, human homologues of genes invo...

XB-ART-5738

Br J Cancer 2003 Feb 24;884:579-85. doi: 10.1038/sj.bjc.6600740.

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hAG-2 and hAG-3, human homologues of genes involved in differentiation, are associated with oestrogen receptor-positive breast tumours and interact with metastasis gene C4.4a and dystroglycan.

Fletcher GC , Patel S , Tyson K , Adam PJ , Schenker M , Loader JA , Daviet L , Legrain P , Parekh R , Harris AL , Terrett JA .

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hAG-2 and hAG-3 are recently discovered human homologues of the secreted Xenopus laevis proteins XAG-1/2 (AGR-1/2) that are expressed in the cement gland, an ectodermal organ in the head associated with anteroposterior fate determination during early development. Although the roles of hAG-2 and hAG-3 in mammalian cells are unknown, both proteins share a high degree of protein sequence homology and lie adjacent to one another on chromosome 7p21. hAG-2 mRNA expression has previously been demonstrated in oestrogen receptor (ER)-positive cell lines. In this study, we have used real-time quantitative RT - PCR analysis and immunohistochemistry on tissue microarrays to demonstrate concordant expression of hAG-2 and hAG-3 mRNA and protein in breast tumour tissues. Tumour expression of both genes correlated with OR (hAG2, P=0.0002; hAG-3, P=0.0012), and inversely correlated with epidermal growth factor receptor (EGFR) (P=0.003). Yeast two-hybrid cloning identified metastasis-associated GPI-anchored C4.4a protein and extracellular alpha-dystroglycan (DAG-1) as binding partners for both hAG-2 and hAG-3, which if replicated in clinical oncology would demonstrate a potential role in tumour metastasis through the regulation of receptor adhesion and functioning. hAG-2 and hAG-3 may therefore serve as useful molecular markers and/or potential therapeutic targets for hormone-responsive breast tumours.

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Species referenced: Xenopus laevis
Genes referenced: ag1 dag1 gpi pigy

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	Figure 1. hAG-2 and hAG-3 show close homology at the protein level and are adjacent to each other at chromosome position 7p21. (A) Protein sequence alignment of hAG-2 and hAG-3 (DNAStar MegAlign programâJotun Hein alignment). The boxed regions on the hAG-3 sequence indicate exact amino-acid matches of hAG-3 with hAG-2. (B) Diagram illustrating the genomic locations, transcriptional orientation, and exon structures of hAG-2 and hAG-3 on chromosome 7p21.
	Figure 2. Immunohistochemical analysis of hAG-2, hAG-3, and ER protein in three separate breast ductal carcinoma donor tissue sections. The boxed region in panels A, D, and G is magnified in panels J, K, and L, demonstrating cytoplasmic staining of hAG-2 (J) and hAG-3 (K) and nuclear staining of ER (L).
	Figure 3. hAG-2, but not hAG-3, protein is expressed in malignant prostate epithelial cells. Immunohistochemical analysis of hAG-2 and hAG-3 in three prostate adenocarcinoma donor tissue sections.
	Figure 4. (A) Diagrammatic illustration of DAG-1 and C4.4a proteins showing the extracellular hAG-2 and hAG-3 minimum binding domains identified by yeast two-hybrid analyses. Although both structures are shown attached to the same cell, it is likely that the interactions of the hAG proteins are autocrine in nature for C4.4a and paracrine for DAG-1. (B) Real-time quantitative RTâPCR analysis of C4.4a mRNA expression in seven donor-matched adjacent normal (N) and tumour (T) breast samples (indicated 1â7) and four human breast cancer-derived cell lines. C4.4a is upregulated in all of the tumour samples, relative to their matched normal tissue, and expressed in all the breast cancer cell lines used to create the yeast two-hybrid prey library. Expression values are described as copies per nanogram of cDNA derived from a standard curve of known dilutions of C4.4a DNA.

References [+] :

Aberger, Anterior specification of embryonic ectoderm: the role of the Xenopus cement gland-specific gene XAG-2. 1998, Pubmed, Xenbase

Aberger, Anterior specification of embryonic ectoderm: the role of the Xenopus cement gland-specific gene XAG-2. 1998, Pubmed , Xenbase
Adam, Comprehensive proteomic analysis of breast cancer cell membranes reveals unique proteins with potential roles in clinical cancer. 2003, Pubmed
Altschul, Basic local alignment search tool. 1990, Pubmed
Côté, Dystroglycan is not required for localization of dystrophin, syntrophin, and neuronal nitric-oxide synthase at the sarcolemma but regulates integrin alpha 7B expression and caveolin-3 distribution. 2002, Pubmed
Fromont-Racine, Toward a functional analysis of the yeast genome through exhaustive two-hybrid screens. 1997, Pubmed
Greenlee, Cancer statistics, 2000. 2000, Pubmed
Heid, Real time quantitative PCR. 1996, Pubmed
Ibraghimov-Beskrovnaya, Primary structure of dystrophin-associated glycoproteins linking dystrophin to the extracellular matrix. 1992, Pubmed
Losasso, Anomalous dystroglycan in carcinoma cell lines. 2000, Pubmed
Moll, The catalog of human cytokeratins: patterns of expression in normal epithelia, tumors and cultured cells. 1982, Pubmed
Morrison, Quantification of low-copy transcripts by continuous SYBR Green I monitoring during amplification. 1998, Pubmed
Petek, Localization of the human anterior gradient-2 gene (AGR2) to chromosome band 7p21.3 by radiation hybrid mapping and fluorescencein situ hybridisation. 2000, Pubmed , Xenbase
Rain, The protein-protein interaction map of Helicobacter pylori. 2001, Pubmed
Rösel, Cloning and functional characterization of a new phosphatidyl-inositol anchored molecule of a metastasizing rat pancreatic tumor. 1998, Pubmed
Sive, Progressive determination during formation of the anteroposterior axis in Xenopus laevis. 1989, Pubmed , Xenbase
Smith, Identification of genes involved in human urothelial cell-matrix interactions: implications for the progression pathways of malignant urothelium. 2001, Pubmed
Sotgia, Caveolin-3 directly interacts with the C-terminal tail of beta -dystroglycan. Identification of a central WW-like domain within caveolin family members. 2000, Pubmed
Thompson, hAG-2, the human homologue of the Xenopus laevis cement gland gene XAG-2, is coexpressed with estrogen receptor in breast cancer cell lines. 1998, Pubmed , Xenbase