CD44v6 in peripheral blood and bone marrow of patients with gastric cancer as micro-metastasis

AIM:To detect the expression of CD44 correlated withthe ability of micro-metastasis in peripheral blood andbone marrow of patients with gastric cancer and to de-duce its clinical significance.METHODS:Preoperative peripheral blood and bonemarrow specimens from 46 patients with gastric cancerand 6 controls were studied by semi-quantitative RT-PCR amplification of CD44v6mRNA.Preoperative andpostoperative peripheral blood specimens from 40patients with gastric cancer and 14 controls were studiedby quantitative RT-PCR amplification of CD44v6rnRNA inthe corresponding period.RESULTS:Semi-quantitative RI-PCR amplificationshowed that CD44v6mRNA expression of peripheralblood and bone marrow was positive in 39 (84.8%)and 40 (86.9%) of 46 patients with gastric cancer,respectively.In peripheral blood,CD44v6mRNAexpression was positive for diffuse type in 30 (93.8%)of 32 patients and for intestinal type in 9 (64.3%)of 14 patients.On the other hand,in bone marrow,CD44v6mRNA expression was positive for diffuse typein 31 (96.9%) of 32 patients and for intestinal typein 10 (71.4%) of 14 patients.There was a significantdifference between the diffuse type and intestinal type.Quantitative RT-PCR amplification demonstrated thatCD44v6mRNA was not expressed in the peripheral bloodof controls and CD44v6mRNA expression was positivefor preoperative peripheral blood in 40 patients withgastric cancer,the expression levels being from 4.9×102 to 3.2×10~5 copies/g RNA.The average expressionlevel of CD44v6mRNA in peripheral blood was 3.9×1010copies/g RNA.The expression levels of CD44v6mRNAin peripheral blood in gastric cancer patients aftercurative operation increased from 5.5×100 to 7.6×10copies/g RNA (P=0.00496).After curative operation,theexpression level decreased markedly.CONCLUSION:Semi-quantitative and quantitative RT-PCR amplification for CD44v6mRNA is a sensitive andspecific method for the detection of micro-metastasis inperipheral blood and bone marrow,which might be usedas an indicator of tumor burden and therapeutic effect.