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Both cyclin D1 and c-myc are key molecules in breast cancer carcinogenesis, and their transcriptional level and stability are regulated through several signaling pathways, including the Wnt signaling pathway. We performed immunohistochemical and mutational analyses of Wnt signaling components to investigate the association of Wnt signaling alterations with breast cancer carcinogenesis using 49 surgically resected primary breast cancer samples. Positive staining of cyclin D1 and c-myc was observed in 55.1% and 30.6% of the 49 breast cancer samples, respectively. Aberrant cytoplasmic expression of β-catenin, which indicates the existence of alterations in the Wnt signaling pathway, was observed in 38.8% of breast cancer samples, though no mutation was found in the β-catenin and Axin 1 genes. Reduced expression of APC was observed in 34.7% of samples. Statistical analysis revealed strong correlations between overexpression of βcatenin and that of cyclin D1 and c-myc (p=0.0001 and 0.0117, respectively). Furthermore, overexpression of β-catenin was significantly correlated with reduced expression of APC (p=0.0127). Wnt signaling alterations were frequently observed in breast cancer from the results of β-catenin immunohistochemistry, although no mutation in the components of the Wnt signaling pathway was found in the present study. Based on the statistical analyses, we speculated that reduced expression of APC leads to overexpression of β-catenin, and aberrant expression of cyclin D1 and cmyc mainly depends on alterations in the Wnt signaling pathway in breast cancer.

Background: It is important to discriminate between primary and secondary lung cancer. However, often, the discriminating diagnosis of primary lung acinar adenocarcinoma and lung metastasis of colorectal cancer based on morphological and pathological findings is difficult. The purpose of this study was to evaluate the clinical usefulness of immunohistochemistry of β-catenin, cytokeratin (CK) 7, and CK20 for the discriminating diagnosis of lung cancer. Methods:We performed immunohistochemistry of β-catenin, CK7, and CK20 in 19 lung metastasis of colorectal cancer samples, 10 corresponding primary colorectal cancer samples and 11 primary lung acinar adenocarcinoma samples and compared the levels of accuracy of the discriminating diagnosis by using antibodies against these antigens.Results: Positive staining of β-catenin was observed in all the lung metastasis of colorectal cancer samples as well as in the primary colorectal cancer samples but in none of the primary lung acinar adenocarcinoma samples. Positive staining of CK7 was observed in 90.9% of the primary lung acinar adenocarcinoma samples and in 5.3% of the lung metastasis of colorectal cancer samples, but in none of the primary colorectal cancer samples. Positive staining of CK20 was observed in all the primary colorectal cancer samples and in 84.2% of the lung metastasis of colorectal cancer samples, but in none of the primary lung acinar adenocarcinoma samples. Conclusion:Combined immunohistochemistry of β-catenin, CK7, and CK20 is useful for making a discriminating diagnosis between lung metastasis of colorectal cancer and primary lung acinar adenocarcinoma. This method will enable accurate diagnosis of a lung tumor and will be useful for selecting appropriate therapeutic strategies, including chemotherapeutic agents and operation methods.

In the present study, we observed that the adenocarcinoma component in the mucosa was continuous with neuroendocrine carcinoma (NEC) in the deeper layers; this suggests the normal course of NEC carcinogenesis at the histological level. A 72-year-old man was admitted to our hospital with a chief complaint of tarry stools. Endoscopic examination of the upper gastrointestinal tract revealed a 2-cm tumor, with a deep central depression, surrounded by a smooth elevated area, in the middle of the stomach body. A biopsy showed that the tumor was a moderately differentiated gastric adenocarcinoma. The patient underwent total gastrectomy and standard lymph node dissection. The resected tumor was a 3.5 × 2.5 cm type 2 lesion. It comprised two elements at the histological level: (i) a moderately differentiated adenocarcinoma in the superficial portion of the mucous membrane layer, and (ii) NEC-like cells with dark, round nuclei and scant cytoplasm, presenting a solid and trabecular pattern, in the submucosal and muscularis propria layers. Immunohistochemical findings showed that the NEC-like cells were diffusely positive for chromogranin A, synaptophysin, neural cell adhesion molecule, and neuron-specific enolase, but were negative for carcinoembryonic antigen. The Ki-67 labeling index was 95%. The final pathological diagnosis was gastric NEC with an adenocarcinoma component and a high cellular proliferative potential.

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