Establishment And Characterization Of A Highly Peritoneal Dissemination Of Human Gastric Carcinoma Cell Line

Although the great advance of the treatment of carcinoma has been obtained,most patients with tumor is still continue died from metastasis which is hardly to control at present. Gastric carcinoma, which incidence rate is the highest in all carcinomas as well as one of the most common malignant tumor in digestive system, affects human's health seriously. The metastasis from stomach to peritoneum is one of most common and most important reason of death.Though some methods including Chemotherapy and surgical operations have improved living quality,there still is no significant approach to control the metastasis and to extend the period of patient's life span.Invasion and metastasis is one of most important characteristic of malignant tumors.Tumor cell culture is one of best methods to research mechanism and characteristics of tumor cells invasion and metastasis. During the last 2 or 3 decades, with the development of the tumor cell identification and tumor marks and the new application of immunodeficiency animal,prosperous future in this field gradually appears.To study the mechanism of cancer invasion and of the prevention of cancer invasion and metastasis,we inject human gastric cell line GC9811 into subcutaneous tissue of nude mice.After forming stable subcutaneous transplanted tumor,the tissue of tumor was transplanted orthotopically under the serosal membrane, compared with the models of direct injecting GC9811 cell suspension under the serosal membrane and the subcutaneous tissue, the abdominal cavity and the caudal vein in nude mice.The tissues remained histologically the characteristic of human gastric adenocarcinoma.The rate of developing tumor both in the model of caudal veine and in the model of direct transplantation orthotopical were 60%;the rate of developing tumor in the model of orthotopically indirect transplantation was 80%;both in the model of subcutaneous tissue and in the model of abdominal cavity was 100%.The rate of metastasis to liver in orthotopically indirect gastric transplantation was 60%,in contrast, direct gastric transplantation for orthotopically was 33.3%(P <0.05),the model of caudal vein transplant was found only metastasis to liver.during the experiment of the model of caudal vein transplant,the histological slice of lungs showed no tumor cell invasion.The transplant tumor cell possesses the function of secreting Carcinoembryonic antigen(CEA), the tumor cells showed mainly fifth-ploid by Cytokinetics detection.It is clear that human gastric cancer model using subcutaneous tumor of nude mice orthotopically transplanted gastric was an ideal model for studying the metastasis mechanism of gastric carcinoma.A effective method to study the metastasis mechanism of both molecule and biology is comparing with those cell lines which have different metastasis ability.Human gastric carcinoma cell line GC9811 was injected into abdominal cavity repeatedly and inoculations in vitro,those tumor cells adapted to nude peritoneum metastasis was rapidely reproduced.The peritoneum with metatatic foci of GC9811 cells were dissected aseptically and then cultured in vitro.The cells in this culture were designated GC9811-P1.The same procedure was repeated using GC9811-P1 cells,and Gc9811-P4 was established upon the fourth cycle of stepwise selection.Using limiting dilution to clone,we were able to obtain a highly metastatic cell strain- GC9811-P.Peritoneum metastasis developed in 12 of 12(100%) nude mice injected with GC9811-P,whereas parental GC9811 developed in 3 of 10( 33.3%).Further,GC9811-P induced faster and larger tumor development than did GC9811-P.However,the primary GC9811 tumor and peritoneum metastatic GC9811-P tumors showed essentially the same histological appearance.Cell cycle of GC9811-P detected by Flow cytometric showed G1 53.5%,G2 12.5%,S 37.1%.whereas parental GC9811 showed G1 57.7%,G2 7.5%, S 34.8%.Genetics characteristics including chromosome morphology remained human karyotype which modal number existed between 104～126 and made up 70%.Western blot analysis demonstrated that the expression of CD44, IL-6,Integrin-α1, MG7 and VEGF strong in GC9811-P compared to GC9811.In contrast,the expression of E-cadherin has no significantly difference in both GC9811-P and GC9811.The data of Flow cytometric analysis coincide with the result of Western blot. These findings suggested that changes in the expression of molecule on the cell surface might play an important role in studying metastatic ability.This well characterized line and its experimental model in vivo should be useful to investigate the mechanisms of peritoneum metastasis and to develop a new therapeutic approach for human gastric cancer. The line with high potential of metastasis should be useful for studies aimed at screening metastatic polypeptide.Conclusion: 1. The model of orthotopic transplantation of gastric carcinoma has same biological characteristic with primary carcinoma. It could be a stable experimental animal model.2. GC9811-P with high metastatic potential to peritoneum and its experimental model in vivo should be useful to investigate the mechanisms of peritoneum metastasis and to develop a new therapeu- tic approach for human gastric cancer.