| The incidence of gastric cancer in our country is the highest one among that of all kinds of malignant turnouTs, and gastric cancer is one of the diseases seriously endanger the health of the people. To explain the causes of gastric cancer at molecule level, search for the molecule marks of gastric cancer and explore the gene therapy of gastric cancer are the bases and directions to improve the level of gastric cancer prevention and cure. Wholly understanding of the changed gene expression patterns in the gastric mucomembranous cells during the converting from normal cells to malignant ones under various conditions, and screening the gastric cancer related genes would provide a credible key to solve these problems.Part One Screening differentially expressed genes in gastric adenocarcmomaby cDNA microarray Objective: To search the differentially expressed genes between gastric adenocarcinoma and normal gastric mucosa using cDNA microarray. Methods: The PCR products of 12 800 human genes were spotted onto a chemical-material- coaled-glass plate in array. DNAs were fixed onto the glass plate afler series of treatments. The total RNAs were isolated from the tissues, and were purified to mRNAs by Oligotex. Both mRNAs from the gastric adenocarcinoma and normal gastric mucosa were reversely transcribed to the cDNAs with the incorporation of fluorescent dUTP to prepare the hybridization probes. The mixed probes were hybridized to the cDNA microarray. After hign-stringent washing, the cDNA microarray was scanned for the fluorescentsignals and showed differences between two tissues. Result: Among the 12 800 target genes, 27 genes differentially expressed prominently in all 5 samples were identified, 11 were up- regulated (0.086%) and 16 down regulated (0.125%). There were 2 novel genes among the down-regulated group. Conclusion: cDNA microarray technique is effective in screening the differentially expressed genes between gastric adencarcinoma and normal gastric mucosa.Part Two Pilot Study of Two Novel Gastric Adenocarcinoma Related GenesObjective: To give a pilot study about the structures and functions of two novel, gastric adenocarcinoma related genes named 1909C01 and lOOlGO7 Method: The homologous genes, open reading frame (ORE), and homologous proteins of the two novel genes are analysed using the databases possessed by National Center of Biotechnology Information (NCBI, Web side: httn:IIwww.ncbi.nlm.nih.~ovI). Then we presumed the possible functions of these two genes. Result: The sequence length of 1909C01 gene is I 55Thp, possessed an ORE of 1323bp, coding for 440aa. This gene has four highly homologous segments with a gene of mouse, AK013305. We also found a segment of I S9bp had 100% homologous with a gene of homo sapiens,FLB3342,but their sequences are in the opposite direction. No ORF and protein with high homologous had been found. The length of another novel gene 1001 G07 is 1 092bp, which possessed a 378bp ORE, coding for 125aa. All sequences of its nucleotide, ORE and amino acid had 99% homologous to homo sapiens cytochrome b5 reductase I (B5R. I) and homo sapiens clone 638 mRNA. Conclusion: The 1001(307 gene may code a protein closely related with the metabolism of the cell. Futher study on these two novel genes would help us wholly understand the gene expression pattern of gastric adenocarcinoma.
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