[Study on novel gene GDDR related to gastric cancer]

To confirm the GDDR cDNA property of novel down-regulated full-length gene in gastric cancer, structure of genomic GDDR DNA and its promotor region. To predict its transcription factors and transcription factor binding sites. To explore function of GDDR gene in vitro.

GDDR mRNA was located by in situ mRNA hybridization of gastric mucous membranes, and was amplified in 13 human organs and tissues. The structure and location of GDDR on chromosome, property of protein encoded by full-length GDDR were investigated by Bio-message technique. Promotor region of GDDR was confirmed, and transcription factors or their binding sites were predicted in software Gene2promoter and Matinspector of Genomatix. Both of vector pcDNA3.1/Myc-His(-)A inserted by GDDR ORF and control vector pcDNA3.1/Myc-His(-)A were respectively transfected into gastric cell lines 7901 by lipofectamin. Growth curve, MTT test and a morphological analysis were respectively performed.

GDDR mRNA was located in gastric mucous epithelial cells, and only was expressed in gastric tissue. 7739 bp genomic GDDR DNA located on chromosome 2p13.3, 21701 bp away from CA11-one stomach-specific gene related to gastric cancer. 618 bp promotor region of GDDR located at position +96 bp,and -419 bp of transcription start site of GDDR. The structure of genomic DNA or cDNA between gene GDDR and CA11 was mostly similar. Sequences of their promotor region were different, transcription factors and their binding sites also varied between gene GDDR and CA11. GDDR encoded protein including a trans-membrane peptide homologed to CA11 that have been proven to encode secrete protein. GDDR was another new member of BRCHOS family just was found. Gastric cell lines 7901 transfected by GDDR showed a marked decrease in growth rate by growth curve and MTT test (72 h, 0.341 +/- 0.014 vs 0.488 +/- 0.015 A, P < 0.01).

Stamoch-specific, novel down-regulated gene GDDR in gastric cancer locates in gastric mucous epithelial cells can markedly inhibit growth of gastric cancer cell lines 7901, GDDR is another new member of BRICHOS family related to gastric cancer except CA11.