Objective: To clone human gastric cancer related gene and to analyze its expression profile in gastric mucosal tissues.
Methods: Paired tumor, paratumor and non-tumor specimens from 7 gastric adenocarcinoma patients (male 4, female 3, with average age 51 +/- 18 years) were studied by means of fluorescent differential display reverse transcription polymerase chain reaction (DDRT-PCR). The differentially expressed cDNA bands of interest were cloned and analyzed by Northern blot and in situ hybridization. Thirty cases (male 23 female 7 with average age 59 +/- 8 years) of paired paraffin-embedded gastric tumor and non-tumor tissues were used in in situ hybridization analysis.
Results: A gene expressed much lower in 6 out of 7 tested tumor samples than in their normal and paratumor counterparts was identified. It was named GCRG123. Northern blot analysis confirmed the differential expression. Human multiple tissue Northern blot analysis showed that GCRG123 expressed in various adult human tissues including thymus, prostate, testis, ovary, small intestine, colon and peripheral blood leukocyte. Sequence analysis revealed that GCRG123 (GenBank accession number AF454554) was a lamin like protein gene. It had one open reading frame which consisted of 49 amino acids (GenBank accession number AAL61668.1). In situ hybridization analysis showed a high GCRG123 expression level in normal gastric epithelium and pylori glands, but low expression level in tumor as well as dysplasia and most intestinal metaplasia at the paratumor regions.
Conclusion: A lamin-like protein gene was identified in human gastric mucosa, it is down-regulated in gastric cancer and its precancerous leisions.