The gastrointestinal tract is lined by a layer of mucus comprised of highly glycosylated proteins called mucins. To evaluate the importance of mucin in intestinal carcinogenesis, we constructed mice genetically deficient in Muc2, the most abundant secreted gastrointestinal mucin. Muc2 ^−/− mice displayed aberrant intestinal crypt morphology and altered cell maturation and migration. Most notably, the mice frequently developed adenomas in the small intestine that progressed to invasive adenocarcinoma, as well as rectal tumors. Thus, Muc2 is involved in the suppression of colorectal cancer.

Interferon (IFN)-γ is necessary for tumor immunity, however, its initial cellular source is unknown. Because γδ T cells primarily produce this cytokine upon activation, we hypothesized that they would provide an important early source of IFN-γ in tumor immunosurveillance. To address this hypothesis, we first demonstrated that γδ T cell–deficient mice had a significantly higher incidence of tumor development after challenge with a chemical carcinogen methylcholanthrene (MCA) or inoculation with the melanoma cell line B16. In wild-type mice, γδ T cells were recruited to the site of tumor as early as day 3 after inoculation, followed by αβ T cells at day 5. We then used bone marrow chimeras and fetal liver reconstitutions to create mice with an intact γδ T cell repertoire but one that was specifically deficient in the capacity to produce IFN-γ. Such mice had a higher incidence of tumor development, induced either with MCA or by inoculation of B16 melanoma cells, compared with mice with IFN-γ–competent γδ T cells. Moreover, genetic deficiency of γδ T cells resulted in impaired IFN-γ production by tumor antigen-triggered αβ T cell upon immunization with tumor lysate. These results demonstrate that γδ T cells can play a necessary role in tumor immunity through provision of an early source of IFN-γ that in turn may regulate the function of tumor-triggered αβ T cells.

Esophageal cancer ranks sixth in cancer death. To explore its genetic origins, we conducted exomic sequencing on 11 esophageal adenocarcinomas (EAC) and 12 esophageal squamous cell carcinomas (ESCC) from the United States. Interestingly, inactivating mutations of NOTCH1 were identified in 21% of ESCCs but not in EACs. There was a substantial disparity in the spectrum of mutations, with more indels in ESCCs, A:T>C:G transversions in EACs, and C:G>G:C transversions in ESCCs (P < 0.0001). Notably, NOTCH1 mutations were more frequent in North American ESCCs (11 of 53 cases) than in ESCCs from China (1 of 48 cases). A parallel analysis found that most mutations in EACs were already present in matched Barrett esophagus. These discoveries highlight key genetic differences between EACs and ESCCs and between American and Chinese ESCCs, and suggest that NOTCH1 is a tumor suppressor gene in the esophagus. Finally, we provide a genetic basis for the evolution of EACs from Barrett esophagus. Significance: This is the first genome-wide study of mutations in esophageal cancer. It identifies key genetic differences between EACs and ESCCs including general mutation spectra and NOTCH1 loss-of-function mutations specific to ESCCs, shows geographic disparities between North American and Chinese ESCCs, and shows that most mutations in EACs are already present in matched Barrett esophagus. Cancer Discov; 2(10); 899–905. ©2012 AACR. Read the Commentary on this article by Collisson and Cho, p. 870. This article is highlighted in the In This Issue feature, p. 857.

Colorectal cancer (CRC) is one of the most common malignant diseases worldwide, but the involved signaling pathways and driven-genes are largely unclear. This study integrated four cohorts profile datasets to elucidate the potential key candidate genes and pathways in CRC. Expression profiles GSE28000, GSE21815, GSE44076 and GSE75970, including 319 CRC and 103 normal mucosa, were integrated and deeply analyzed. Differentially expressed genes (DEGs) were sorted and candidate genes and pathways enrichment were analyzed. DEGs-associated protein–protein interaction network (PPI) was performed. Firstly, 292 shared DEGs (165 up-regulated and 127 down-regulated) were identified from the four GSE datasets. Secondly, the DEGs were clustered based on functions and signaling pathways with significant enrichment analysis. Thirdly, 180 nodes/DEGs were identified from DEGs PPI network complex. Lastly, the most significant 2 modules were filtered from PPI, 31 central node genes were identified and most of the corresponding genes are involved in cell cycle process, chemokines and G protein-coupled receptor signaling pathways. Taken above, using integrated bioinformatical analysis, we have identified DEGs candidate genes and pathways in CRC, which could improve our understanding of the cause and underlying molecular events, and these candidate genes and pathways could be therapeutic targets for CRC.