Clone And Identify Gene CDNA Fragments Related To Gastric Cancer And Its Premalignant Lesion

PURPOSEThe fluorescent differential display technique was used to clone differentially expressed genes among gastric cancer, its premalignant lesion and normal gastric tissue. It might be helpful to understand the molecular mechanism of tumor formation, early diagnosis and treatment of gastric cancer.MATERIALS AND METHODSWe collected 30 gastric cancers and matched normal gastric mucosal tissues, 10 precancerous lesions. All specimens were confirmed by pathological diagnosis. Total RNA was extracted using TRIzol reagent from each sample, 3 of each group were used to carry out mRNA differential display. PCR products were separated by sequencing gel electrophoresis, and then differentially expressed genes were excised from the gel and re-amplified. After being cloned, cDNA fragments were sequenced. Through BLAST software, the sequencing results were compared with GenBank database for homology analysis. The differential expressions were confirmed by Northern blot and RT-PCR.RESULTSSeven differentially expressed cDNA fragments were found. 1709 was over-expressed in gastric cancer, it had the homology of 99% with the ribosomal protein S24 gene. 8202-1,8202-2 and 8206 were up-regulated in gastric cancer and precancerous lesion, they had high homology with known sequences in GenBank database, but their functions were unknown. 8201 and 820E expressed lower in gastric cancer. 820D and 820J were down-regulated in gastric cancer and precancerous lesion. 8201 had the homology of 100% with the motility-relatedprotein-1 gene. RT-PCR confirmed the differential expression; further research found its expression in intestinal type gastric cancer was higher than that in diffuse type gastric cancer. 820D and 820J had the identical sequence, they and 820E had extremely low sequence identity with any genes from GenBank and sequences from EST database. The sequence data was submitted to dbEST with accession No.CD454989 and CB833297 and Northern blot confirmed their expressions.CONCLUSIONSWe found seven differentially expressed gene cDNA fragments, they might be involved in the gastric carcinogenesis.1. Two have high homology with known genes, of which one was ribosomal protein S24 gene, the other was motility-related protein-1 gene.2. Two have no evident homology with known genes, they might be novel gene fragments.3. Three have high homology with known sequences in GenBank database, but their functions are unknown.