Impact of the Surgical Peritoneal Environment on Pre-implanted Tumors on a Molecular Level: A Syngeneic Mouse Model

BackgroundWe recently demonstrated that a CO2 pneumoperitoneum at either a high or low IPP has few if any short term effects on peritoneal dissemination when tumors are well established before surgery. The objective of the present study was to evaluate the impact of the surgical peritoneal environment on pre-implanted tumors on a molecular level.Materials and MethodsOn day 7, C57BJ6 mice received an intraperitoneal inoculation of a mouse ovarian cancer cell line (ID8). On day 0, mice were randomized into four groups: anesthesia alone, CO2 pneumoperitoneum at a low (2 mm Hg) or high (8 mm Hg) IPP, or laparotomy. Groups were further subdivided into four groups and a laparotomy was performed to collect pre-implanted tumors on POD 1, 2, 7, or 14. Expression levels of β-1 integrin, cMet, uPA, uPAR, and PAI-1 mRNA in pre-implanted nodules were measured using real-time PCR.ResultsExpression levels of uPA, uPAR, and cMet mRNA were significantly higher in the laparotomy group than in the control group on POD 1. We detected significantly higher expression levels of uPAR and cMet in the laparotomy group than in the control group on PODs 2 and 7. There were no significant differences in the expression levels of any genes examined among the low IPP, anesthesia alone, and control groups on POD 1, 2, 7, or 14.ConclusionThe impact of a CO2 pneumoperitoneum at a low IPP on gene expression levels of pre-implanted tumors might be minimal until POD 14 in the present mouse model.