ABSTRACT
<p><b>OBJECTIVE</b>To explore the effects of 5-Aza-2'-deoxycytidine on spleen tyrosine kinase (Syk) expression by inhibition of DNA methylation and the effect of re-activation of Syk on oncogenesis of gastric cancer.</p><p><b>METHODS</b>Syk mRNA of SGC7901, MGC803, MKN28 and MKN45 cell lines were analyzed by RT-PCR, and Syk methylation were detected by MSP. 5-aza-CDR was used to incubate with human gastric cancer cell line SGC7901, Methylation of Syk promoter region was detected by MSP and RT-PCR technique was used to detected Syk gene in the methylated and silenced Syk gene in the cell line SGC7901. Meanwhile, cell lines were inoculated into subcutaneous tissue of nude mice.</p><p><b>RESULTS</b>No Syk mRNA were found in SGC7901 and MKN45 gastric cancer cell lines, but methylation of Syk were detected in those cell lines. No methylation of Syk promoter region was found and Syk gene was detected in the Syk-negative cell line SGC7901 after incubated with 5-aza-CDR. Of 10 nude mice which were inoculated SGC7901(Syk(+)), 3 were observed macroscopic tumor 8 weeks after the injection. On contrast, tumors were found in 10 nude mice which were inoculated SGC7901 (Syk(-)) 8 weeks after the injection, a significant difference was noted between the two groups (chi (2)=7.91, P<0.05).</p><p><b>CONCLUSION</b>Syk gene is re-expressed in the cell line SGC7901 by demethylation with 5-aza-CDR. Syk gene re-expression suppress the malignant oncogenesis and growth of human gastric cancer.</p>
Subject(s)
Animals , Female , Humans , Male , Mice , Azacitidine , Pharmacology , Cell Line, Tumor , CpG Islands , DNA Methylation , Gene Expression , Intracellular Signaling Peptides and Proteins , Metabolism , Mice, Nude , Promoter Regions, Genetic , Protein-Tyrosine Kinases , Metabolism , Stomach Neoplasms , Metabolism , Pathology , Syk KinaseABSTRACT
<p><b>OBJECTIVE</b>To evaluate the clinical significance of CK20 mRNA expression in detecting disseminated tumor cells in peripheral blood of gastric and colorectal cancer patients.</p><p><b>METHODS</b>Expression of CK20 mRNA was investigated by RT-PCR in bone marrow, portal vein and peripheral blood in 47 gastric, 58 colorectal cancer patients and 6 non-cancer volunteers. All the patients were followed-up for one year.</p><p><b>RESULTS</b>There was no positive expression of CK20 mRNA in 6 non-cancer volunteers. The positive rates of CK20 mRNA in bone marrow, portal vein were 87.2% (41/47) and 85.1% (40/47) in gastric cancer, and were 77.6% (45/58) and 74.1% (43/58) in colorectal cancer. The positive rates of CK20 mRNA in peripheral blood in gastric and colorectal cancer patients were 42.6% (20/47) and 44.8% (26/58) by one single test, and were 74.5% (35/47) and 69.0% (40/58) by two tests. The overall positive rate of CK20 mRNA in peripheral blood (two tests) was similar to that in bone marrow and portal vein. The overall positive rate of CK20 mRNA in peripheral blood was higher in two tests than in one single test (P < 0.05) and in advanced than early lesions. The relapse rate within one year was higher in CK20 mRNA positive patients than the negative ones (P < 0.05).</p><p><b>CONCLUSION</b>Detection of cancer cells by RT-PCR for CK20 mRNA in peripheral blood, being as sensitive and specific as in bone marrow and portal vein, is reliable and convenient in diagnosing micrometastasis of gastric and colorectal cancer, which possesses clinical significance in assessing the prognosis and scheme of therapy.</p>