Einfluß von Laparotomie und CO2-Pneumoperitoneum auf die Tumorbiologie des menschlichen Kolonkarzinoms in der SCID-Maus
The influence of laparotomy and CO2 pneumoperitoneum on the tumour biology of human colon carcinoma in the SCID mouse
Backround: The role of laparoscopy in the surgery of colon carcinoma is unclear, particularly from the oncological point of view. In this study, the effect of CO2 pneumoperitoneum on the development of human colon carcinoma independent of the influence of the immune system is examined. Method: Immune-deficient SCID mice (25–30 g, n=8) were randomised into three groups. Under anaesthesia [Rompun (15 mg/kg)/ketamin (75 mg/kg)] the animals each underwent either median laparotomy (LT) or laparoscopy (LS) over a period of 20 min (CO2 pneumoperitoneum 5 mmHg). Prior to surgery, 1 x 107 human colon carcinoma cells of cell line type HCT 116 in 50 µl PBS were introduced under observation into the upper abdomen. The control group (C) underwent no surgery following cell injection. On post-operative day (POD) 14 autopsy of the animals was carried out. The percentage loss in body mass, the mass of the tumour in the parietal peritoneum (g), total metastatic tumour volume (mm3), as well as the number of organs affected by metastasis were determined. Furthermore, the tumour was immunohistochemically labelled with regard to the proliferation marker Ki-67, the cell-cell adhesion molecules alpha- and beta-catenin and the cell-extracellular matrix adhesion molecules CD44 V5 and V6, with subsequent quantification using interactive image analysis (percentage proportionate area). Finally, the expression of matrix metalloproteinase (MMP2) in the tumour tissue was measured by means of quantitative, competitive RT-PCR using a gene-specific external standard. Statistics: multivariance analysis, Tukey’s Test. Results: On POD 14 there was a significantly higher loss in mass in the LS group in comparison with the C group (LS, 12.41±1.94; C, 6.19±1.65; p<0.05). There were no significant differences between the LS and LT groups recorded. Total metastatic tumour volume was significantly greater in the LS group in comparison with the LT group (LS, 668.8±250.7; LT, 439.3±186.1; p<0.05). Simultaneously, both the LS and the LT groups displayed a greater number of affected organs when compared with the C group (LS, 13.1±2.1; LT, 13.3±1.6; C, 11.1±2.0; p<0.05). Immunohistochemical review revealed significantly reduced expression on alpha-catenin (LS, 6.0±0.8; LT, 7.3±0.4; p<0.01) and raised expression on CD44 V5 (LS, 35.6±1.4; LT, 12.8±0.7; p<0.01) in the tumour tissue in the LS group. With reference to proliferation marker Ki-67 and expression of MMP2, no significant differences were observed. Conclusion: Both the weaker expression on alpha-catenin as well as the raised expression on CD 44 V5 may be the representation of increased metastasis. The expression pattern of proteins associated with tumour progression together with the macroscopically determined increase in metastasis in the SCID mouse model point to the increased risk associated with laparoscopy in the case of colon carcinoma.
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