Effects Of Carbon Dioxide Pneumoperitoneum On Gastric Cancer Cellular Proliferation And Invasion

Objects:Gastric cancer is the most common digestive tract malignant tumor in our country with second death rate on the cancer death list,which is 23.03%of total.Resection is the only way of radical cures but which brings great wounds,slow post-operational recovery and multiple coincidences.On the dawn of 21 century,minimally invasive surgery came to be the new navigation light of surgery,in which the laparoscopic technology developed most quickly.Laparoscopic radical resection of colorectal cancer,is widely practiced in the fields of general surgery.And it has been proved that laparoscopic radical resection of colorectal cancer had at least same effects of cancer treatment comparing with open surgery,with less pain,faster recovery,little interference of physiological function and lower coincidence.The success of colorectal cancer laparoscopic radical operation greatly inspires the attempt of laparoscopic radical gastrectomy.With the improvement of technique and equipments,domestic laparoscopic radical gastrectomy is practiced extensively and show promised recent effects,even most operations were done on patients with cancer in early stage.There are few D2 laparoscopic radical gastrectomies have been applied on progressed cancer patients because of complex anatomy structure,abundant lymphoid drainage and difficulty of laparoscopic digestive tract reconstruction.Moreover, there are great concerns of metastasis promotion by carbon dioxide pneumoperitoneum.It will be of great importance to investigate the relationship of carbon dioxide pneumoperitoneum and gastric cancer cellular proliferation and invasion.Methods:1 Different groups of cultured human gastric cancer strain MNK-45 were exposed under in vitro carbon dioxide pneumoperitoneum model.After exposion,pH was test and MTT chronometry was used to detect cell growth.Cell cycles and index of proliferation were detected by flow cytometry.2 Adhesive kit and Transwell chamber were used to investigate the influence on adhesive capacity,mobility and invasion ability of exposed gastric cancer cell.The different time point expressions of CD_44v6,ICAM-1 and E-cadherin were detected by flowcytometry.MMP₂ and MMP₉ expressions were detected by Werstern-blot.3 The nude mice tumor models were built with the exposed cancer cells by injection into abdomen and were be observed extensively.Results:(1) Exposed groups of gastric cancer cell show slow growth comparing control under in vitro carbon dioxide pneumoperitoneum model but the groups under 9mmHg and 12mmHg do not show statistic significance,while the group under 15mmHg drops significantly,pH of every group drops obviously and related to pressure.(2) The in vitro adhesive ability of group under 15mmHg raised significantly 48h after exposition and drops at 96h,while groups under 9 and 12mmHg show no significant rise.(3) Cellular adhesive molecule CD_44v6 in all groups express high after exposition but drops with time. The 15mmHg group CD_44v6 expression raised obviously after exposition,and very significantly expression was detected and 24h and 48h,while the 9 and 12mmHg groups CD_44v6 expressions raised very significantly at 24h but drops at 48h and show no significantly difference at 72h verse control.Cellular adhesive molecule ICAM-1 in all groups show similar expression with CD_44v6 but raised more quickly right after exposition. The expressions reach the peak at 48h and the drop to control level at 72h.Cellular adhesive molecule E-cadherin expression in all groups drop to lowest point right after exposition and then rise gradually to control level at 48h.(4) The invasion ability of exposed gastric cancer cell line MKN-45 under 9 and 12mmHg show no significant change, while that of 15mmHg group obviously raised.The expressions of MMP₂ and MMP₉ rise significantly in every group at 12 and 24h,but then drop after 24h and reach control level at 72h.(5)In mice tumor model the tumor number,total tumor weight and organic distribution show no difference verse control.In addition,there is no significant difference in survival rate among nude mice groups.Conclusion:(1) The carbon dioxide pneumoperitoneum pressure used in clinical practice may have no influence on gastric cancer cell proliferation.(2) The carbon dioxide pneumoperitoneum pressure of 9 and 12mmHg do not promote gastric cancer cell adhesive ability,while 15mmHg does obviously.The mechanism may due to the expressions of CD_44v6 and ICAM-1,or suppression of E-cadherin.(3) The carbon dioxide pneumoperitoneum pressure of 9 and 12mmHg do not promote gastric cancer cell mobility and invasion,while 15mmHg does.The mechanism may due to promotion of MMP₂ and MMP₉ expressions.(4) The carbon dioxide pneumoperitoneum pressure lower than 15mmHg do not promote gastric cancer growth in animal model,which may indicate usage in clinical D2 laparoscopic radical gastrectomy applied on progressed cancer patients.