The Relationship between LRP6 and Wnt/ß-Catenin Pathway in Colorectal and Esophageal Cancer.

High expression of low-density lipoprotein receptor-related protein 6 (LRP6), a key component of the Wnt/ß-catenin signaling pathway, is reported to be associated with malignant potential in some solid tumors including breast cancer and hepatocellular carcinoma. Few reports, however, have examined its function and clinical significance in colorectal cancers (CRC) demonstrating constitutive activation of Wnt signaling. Here, we compared the expression level and function of LRP6 in CRC with that of esophageal squamous cell carcinoma (ESCC) bearing few Wnt/ß-catenin pathway mutations. On immunohistochemical staining, high LRP6 expression was noted in three of 68 cases (4.4%), and high ß-catenin in 38 of 67 cases (56.7%) of CRC. High LRP6 expression was found in 21 of 82 cases (25.6%), and high ß-catenin expression in 29 of 73 cases (39.7%) of ESCC. In our in vitro studies, LRP6 knockdown hardly changed Wnt signaling activity in CRC cell lines with mutations in Wnt signaling downstream genes. In contrast, in ESCC cell lines without Wnt signaling-related mutations, LRP6 knockdown significantly decreased Wnt signaling activity. LRP6 function may depend on constitutive activation of Wnt signaling.

Mesothelial cells facilitate cancer stem­like properties in spheroids of ovarian cancer cells.

Ovarian cancer is characterized by widespread peritoneal dissemination with ascites. Spheroids observed in the ascites of ovarian cancer patients are a mixture of cancer cells and mesothelial cells. In the present study, we evaluated whether mesothelial cells exfoliated from the peritoneum facilitate tumor spheroid formation and give rise to cancer stem­like properties in ovarian cancer cells. Spheroids from the CAOV3 and A2780 ovarian cancer cell lines grew much larger in co­culture with mesothelial cells than in monoculture under 3D conditions. The spheroids in co­culture displayed high Ki­67 expression in the peripheral zone and low expression in the central zone area. The expression of CD133 emerged in the inner portion of spheroids at later time­points (96 and 168 h), indicating that cancer cells expanded to the inner spheroid and acquired stem cell­properties. The mRNA levels of cancer stem cell markers Dclk­1, CD44 and Bmi­1 significantly increased in co­cultured CAOV3 and mesothelial cells compared to CAOV3 cells alone. Furthermore, the mesothelial cells promoted the tumorigenesis and growth of the CAOV3 cells in a mouse xenograft model compared to cancer cells alone. In conclusion, mesothelial cells promoted spheroid formation by ovarian cancer cells and facilitated cancer stem­like properties.

Evaluation of matrix metalloproteinase-2 (MMP-2) activity with film in situ zymography for improved cytological diagnosis of breast tumors.

BACKGROUND: Fine-needle aspiration (FNA) biopsy of breast tumors is a reliable diagnostic method for identifying breast carcinoma. However, it is sometimes difficult to definitely distinguish malignant from benign lesions. To improve the cytological diagnosis of breast tumors, we investigated the expression of active matrix metalloproteinase-2 (MMP-2), as detected by film in situ zymography (FIZ). METHODS: We evaluated 34 fresh breast tumors, 25 paraffin-embedded breast tissue specimens, and a human cancer cell line (HT1080). MMP-2 expression was determined by immunocytochemistry or immunohistochemistry. Frozen sections and aspiration cytology samples of breast cancer were incubated on gelatin-coated films for the detection of active MMP-2. RESULTS: Immunohistochemistry showed that MMP-2 was expressed in cancer cells and stromal cells, but not in most benign breast lesions. Active MMP-2, but not pro-MMP-2, in the conditioned medium of HT1080 cells showed gelatinolytic activity on FIZ analysis, while the expression of both forms of MMP-2 was detected by immunocytochemistry. Gelatinolytic activity was also detected by FIZ analysis of aspiration cytology samples and frozen sections from the breast cancers, and there was a significant correlation between this gelatinolytic activity and the detection of MMP-2 expression by immunocytochemistry. CONCLUSIONS: The present study demonstrated that measurement of gelatinolytic activity by FIZ analysis of aspiration cytology samples may be useful for improving the cytological diagnosis of breast tumors.