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Background/aims: The employment of laparoscopy in the treatment of locally advanced colorectal cancer is still questioned by many surgeons, mainly due to the fear of spreading tumors by the laparoscopic procedure. However, it is still unknown whether laparoscopy is actually associated with increased tumor dissemination, especially for those with tumor invasion through the serosa. The main purpose of this study is to investigate the effect of pneumoperitoneum on the intra-abdominal tumor growth and spreading of colon cancer cells by an animal study of murine model., Methodology: Under anesthesia, 10(6) tumor cells (CT26) were inoculated into the lower abdominal cavity of BALB/c mice by a mini-laparotomy. The mice were randomized to undergo pneumoperitoneum with CO2 (n=10), helium (n=10), or to act as controls (n=10). Pneumoperitoneum was established over 20 min at a pressure of 10cm H2O. The distribution pattern and the weight of peritoneal tumor growth of each mouse were recorded and analyzed at 15 days after surgery., Results: The mean ratios of the tumor mass over the total body weight of the mice were 0.77+/-1.13% (control group), 4.30+/-0.86% (CO2 pneumoperitoneum), and 2.17+/-0.88% (helium pneumoperi-toneum). The mean tumor weight ratio (3.23+/-1.38%) of the pneumoperitoneal group was 4 times larger than that of the control group (p<0.001). Regarding the use of different insufflation gases over tumor growth, CO2 accelerates tumor growth more significantly than helium (p<0.001). Intraabdominal distribution (p=0.047) and diaphragm spreading (p<0.001) were significantly greater in the pneumoperitoneum group than the control group., Conclusions: The results of this animal study imply that presence of a pneumoperitoneum enhances the implantation and growth of free intraperitoneal malignant colon cancer cells in this in vivo mouse model. The results of the current study suggest that insufflation during pneumoperitoneum may play an important role in the development of peritoneal dissemination when there are free tumor cells in the intra-abdominal cavity, and the effect of using CO2 might be greater than that of using helium.

Aim: We optimized a rapid and efficient tissue lysis method using the MagNA Lyser (Roche, Germany). Using this novel method combined with immunoblot analysis, we investigated the correlation between abnormal Bcl-X(L) expression and clinicopathological characteristics in colorectal cancer., Methods: Tissue samples from Sprague-Dawley rats were tested to determine optimal lysis conditions for use with MagNA Lyser. We next used the new method to extract tissue proteins from the tumor tissue of a colorectal cancer patient. The availability of extractable tissue proteins for proteomic study was demonstrated by two-dimensional (2D) gel electrophoresis and subsequent matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. In addition, we prepared tissue lysates from paired tumor tissues and adjacent nontumor tissues of 50 colorectal carcinoma patients. Ensuing immunoblot analyses were performed to detect the level of Bcl-X(L) expression., Results: The optimal sample sizes processed were found to be around 200 mg, with oscillation frequency of 6500 r/min for 80 s. Test of the first human tissue lysate confirmed that the MagNA Lyser method was adequate for protein extraction and subsequent identification by current proteomic protocols. The method was also applicable to immunoblot analysis. Thirty of 50 (60%) colorectal patients exhibited higher level of Bcl-X(L) expression in their tumor tissues. Raised level of Bcl-X(L) expression correlated with patients' gender and tumor cell proliferation index (P = 0.037 and P<0.001, respectively), but was independent of clinicopathological characteristics and overall survival., Conclusion: We report a novel tissue lysis method applicable to proteomic and immunoblot analyses, which can facilitate the discovery and detection of cancer protein alterations.