The role of mesenchymal stem cells (MSCs) in tumorigenesis remains controversial. Therefore, our goal was to determine whether exogenous MSCs possess intrinsic antineoplastic or proneoplastic properties in azoxymethane (AOM)-induced carcinogenesis. Three in vivo models were studied: an AOM/dextran sulfate sodium colitis-associated carcinoma model, an aberrant crypt foci model, and a model to assess the acute apoptotic response of a genotoxic carcinogen (AARGC). We also performed in vitro coculture experiments. As a result, we found that MSCs partially canceled AOM-induced tumor initiation but not tumor promotion. Moreover, MSCs inhibited the AARGC in colonic epithelial cells because of the removal of O 6 -methylguanine (O 6 MeG) adducts through O 6 MeG-DNA methyltransferase activation. Furthermore, MSCs broadly affected the cell-cycle machinery, potentially leading to G1 arrest in vivo. Coculture of IEC-6 rat intestinal cells with MSCs not only arrested the cell cycle at the G1 phase, but also induced apoptosis. The anti-carcinogenetic properties of MSCs in vitro required transforming growth factor (TGF)-b signaling because such properties were completely abrogated by absorption of TGFb under indirect coculture conditions. MSCs inhibited AOM-induced tumor initiation by preventing the initiating cells from sustaining DNA insults and subsequently inducing G1 arrest in the initiated cells that escaped from the AARGC. Furthermore, tumor initiation perturbed by MSCs might potentially dysregulate WNT and TGF-b-Smad signaling pathways in subsequent tumorigenesis. Obtaining a better understanding of MSC functions in colon carcinogenesis is essential before commencing the broader clinical application of promising MSC-based therapies for cancer-prone patients with inflammatory bowel disease. STEM CELLS 2014;32:913-925

Background/AimsAlthough multiple treatment options exist for the management of sigmoid colon volvulus, no study has examined the factors associated with successful endoscopic detorsion. This study aimed to examine the clinical course of patients with sigmoid colon volvulus and to identify factors related to successful endoscopic detorsion.MethodsThis study included 30 cases (21 patients) of sigmoid volvulus from among 545 cases of intestinal obstruction at a single center. We retrospectively examined the clinical course and the factors associated with the possibility of endoscopic detorsion of sigmoid colon volvulus.ResultsThe rate of laxative use among the study participants was 76.2%; the rate of comorbid neuropsychiatric disorders was 61.9%; and 57.1% of patients had a history of open abdominal surgery. All patients were initially treated with endoscopic detorsion, and this procedure had a 61.9% success rate. The recurrence rate after detorsion was as high as 46.2%, but detorsion during revision endoscopy was possible in all cases. Statistical analysis revealed that the absence of abdominal tenderness (P=0.027), the use of laxatives (P=0.027), and a history of open abdominal surgery (P=0.032) were factors predictive of successful endoscopic detorsion.ConclusionsThe results of our study are consistent with previous reports with respect to the success rate of endoscopic detorsion, the subsequent recurrence rate, and the proportion of patients requiring surgical treatment. In addition, we identified the absence of abdominal tenderness, the use of laxatives, and history of open abdominal surgery as factors predicting successful endoscopic detorsion of sigmoid colon volvulus.

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Trastuzumab has recently been introduced as a treatment for HER2-positive metastatic and/or unresectable gastric cancer (MUGC); however, compared with breast cancer, some issues concerning HER2 and trastuzumab therapy for gastric cancer remain unclear. A 74-year-old woman received trastuzumab-containing chemotherapy for HER2-positive MUGC. She had a marked response to 8 months of chemotherapy, and gastrectomy and hepatic metastasectomy with curative intent were performed. The resected specimen showed complete loss of HER2 positivity in the residual tumor. For MUGC, a change in HER2 status during the course of the disease with or without chemotherapy has rarely been reported. However, in breast cancer, a significant frequency of change in HER2 status during the course of disease has been reported, and reevaluation of HER2 positivity in metastatic/recurrent sites is recommended. The choice of trastuzumab for MUGC is currently based on the HER2 status of the primary tumor at the time of initial diagnosis, without reassessment of HER2 status during the course of disease and/or in metastatic/recurrent sites, on the assumption that HER2 status is stable. However, our case casts doubt on the stability of HER2 in gastric cancer.

The patient was a 57-year-old man who was diagnosed with multiple lung metastases of sigmoid colon cancer. The patient developed progressive disease after 8 courses of bevacizumab + capecitabine and oxaliplatin therapy, therefore, bevacizumab + irinotecan, leucovorin, and 5-fluorouracil therapy was started. During the fifth course, he experienced pain on the left side of his chest. On computed tomography, bleeding from the pulmonary metastatic lesions was suspected. Two days later, a pneumothorax was detected. Although several cases of pneumothorax induced by bevacizumab have been reported, this case is the first documentation that bevacizumab caused a rupture of the lung metastatic lesion, leading to a pneumothorax.