Differential Display Of MRNA For Hepatic Metastasis Associated Genes Of Gastric Cancer

Objective: To investigate differential expression of hepatic metastasis associated genes of gastric cancer, and evaluate it as a marker predicting liver metastasis of human gastric cancers.Methods: Differential display PCR (DD-PCR) was used to display the differential genetic expression among 2 primary foci with hepatic metastasis, primary foci without metastasis and normal gastric mucosa individually. The total RNA was isolated from the tissues, reversed transcribed to cDNA and amplified by PCR. The PCR products were displayed and identified on a polyacrylamid gel (PAGE) by EB staining and the differentially expressed bands were retrieved and reamplified. Molecular cloning techniques were applied to the differential segments in hepatic metastasis. After clone, all cDNA fragments were sequenced. Through BLAST software, the sequencing results were compared with GenBank database for homology analysis. Expression of HERV in 9 primary foci with hepatic metastasis, primary foci without metastasis and normal gastric mucosa tissues respectively were identified by RT-PCR..Results: Significant differential expressions were found among primary foci with hepatic metastasis, primary foci without metastasis and normal gastric mucosa tissues individually. Ten segments of differential expression were discovered in hepatic metastasis, and all of them were over-expressed. Subsequently, we selected two differential segments of Wl and W6 for sequencing, homologous comparison, detection of clinical specimens and making further investigation. Compared with database, Wl gene (265bp) was homology of mitochondria DNA and W6 gene was similar to HERV gene (99%). Positive expression rate of HERV gene was detected 88.9% in all 9 hepatic metastasis by means of RT-PCR. The differences are significant (P<0.01) through Fisher test.Conclusion: 1 The present investigation with mRNA differential display suggests that abnormal expressions of the ten genes may play an important role in hepatic metastasis of gastric carcinoma 2 These genes are induced by up-regulation of the oncogen, so we presume that hepatic metastasis of gastric cancer is partly caused by the mutation of oncogen, not that of suppressor-gene. 3 HERV gene is more widely expressed in primary foci with hepatic metastasis than in primary foci without metastasis, indicating that it can act as a maker...