| PerfaceThe current surgical and chemotherapeutic therapies of human gastric carcinoma are often unsuccessful unless the tumor is detected at early stage. Peritoneal metastasis is the most common postoperative recurrence of gastric cancer with radical resection, which have been one of the key factors affecting treatment effect and prognosis in advanced gastric carcinoma. The perception of peritoneal seeding and the treatment of subclinical foci in peritoneal cavity have been known as an important subject in gastric cancer surgery in the recent years. Despite the importance of peritoneal metastasis in mediating the morality of gastric carcinoma, little is known about the mechanism of this phenomenon. At the present time, peritoneal metastasis is regarded as a multistep process, which is caused by the interaction between specific tumor cells and circumstance in peritoneal cavity, and involved in the mechanisms of cell mobility, adhesion, degradation of matrix, angiogenesis, etc. It has been demonstrated that adhesion molecules, matrix metalloproteinases, cytokine and some of the metastasis - related genes play important roles in the course of peritoneal metastasis. As for diagnosis, detecting the exfoliated cancer cell ( ECC ) in peritoneal lavage fluid is regarded as the most useful method at the present time, though its coincident rate is only 40 - 60%. So it is significantto probe into the mechanism of peritoneal metastasis in gastric cancer and develop the routes of finding free cancer cells in peritoneal cavity. In this study, we detected the mRNA levels of CD44, integrin pi, TGF - 1 and S100A4 in peritoneal lavage fluid or ascites of patients with gastric cancer by reverse transcription polymerase chain reaction ( RT - PCR) , and investigated the relationships between these levels and peritoneal metastasis and peritoneal metastasis - related factors of gastric cancer.MethodsThe ascites and peritoneal lavage fluid of fifty patients with gastric cancer were collected from oncology department, the first clinical college, China Medical University from Oct 2001 to Jan 2002, including 5 cases of early gastric cancer and 45 cases of advanced gastric cancer. Patients who undergone chemotherapy and radical therapy were excluded. We collected about 50ml of ascites or peritoneal lav-age fluid per case in operation-20ml of it were used to detect free cancer cells by ECC in the pathology department, the other 30 ml were centrifuged at 2000 cycles per minute for 10 minutes at 2 - 8T1 ; then were removed the supernatant, isolated RNA of the cells in the deposit by TRIZOL reagent, changed RNA into cDNA by the process of reverse transcription, detected the expression of CD44, integrin 31, TGF - (31 and S100A4 mRNA by PCR reaction and electrophore-sis, analyzed the electrophoretic images by Gel work - ID software, lastly, calculated the values representing the expressive levels of mRNA.ResultsThe positive expression rate of CD44 mRNA was 86% (43/50) in all the 50 cases of peritoneal lavage fluid or ascites. The level of CD44 mRNA's expression was closely related to serosal type, peritoneal metastasis (P <0. 05) , TNM stages of gastric cancer and results of ECC (P < 0. 01). 25 of 50 cases of peritoneal lavage fluid or ascites showed the existence of integrin mRNA with the positive rate of 50% (25/50). As a whole, the level of integrin mRNA's expression of the cases having occurred peritoneal metastasis was higher than that of the ones without it( P <0.05). We found TGF - 1 mRNA in all 50 cases. Its expression level was significantly related to serosal type, results of ECC and TNM stages(P < 0.05 ). The positive rate of S100A4 mRNA is 100% too. There was important correlations between the expressive level of S100A4 mRNA and TNM stage (P <0. 05) and results of ECC( P < 0. 01). In all 50 cases, there were 45 or 23 cases expressed three or four kinds of mRNA, respectively. There were rises in positive rates of ECC and peritoneal metastasis along with the increase in kinds of expression of mRNA. In di...
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