Genomic analysis of a case of multifocal adenocarcinoma in ulcerative colitis

An evolutionary perspective on field cancerization

Tumorigenesis begins long before the growth of a clinically detectable lesion and, indeed, even before any of the usual morphological correlates of pre-malignancy are recognizable. Field cancerization, which is the replacement of the normal cell population by a cancer-primed cell population that may show no morphological change, is now recognized to underlie the development of many types of cancer, including the common carcinomas of the lung, colon, skin, prostate and bladder. Field cancerization is the consequence of the evolution of somatic cells in the body that results in cells that carry some but not all phenotypes required for malignancy. Here, we review the evidence of field cancerization across organs and examine the biological mechanisms that drive the evolutionary process that results in field creation. We discuss the clinical implications, principally, how measurements of the cancerized field could improve cancer risk prediction in patients with pre-malignant disease.

Wnt pathway-related gene expression during malignant progression in ulcerative colitis

Long-standing ulcerative colitis (UC) has been associated with a high risk of developing colonic adenocarcinoma. Importantly, both low- and high-grade dysplasia are strongly related to the presence or development of malignancy. The canonical Wnt/beta-catenin signaling pathway is of crucial importance in cancer development and progression, but its role in UC-related carcinogenesis remains to be determined. We evaluated the immunolabeling patterns of beta-catenin, as well as the products of Wnt-associated cancer genes E-cadherin, cyclin D1 and c-myc, along the dysplasia-carcinoma pathway in UC. For this purpose, immunohistochemistry (IHC) was performed on 18 adenocarcinomas and 17 dysplasias, derived from 21 patients. We found that intracellular beta-catenin accumulation, the hallmark of Wnt signaling activation, is observed in dysplasia, together with enhanced labeling of nuclear protein cyclin D1 and reduction of membranous labeling of E-cadherin. c-myc displayed moderate immunolabeling in the (pre)malignant lesions. Thus, the Wnt pathway is activated in early stages of malignant progression in UC. Furthermore, upregulation of the oncogene cyclin D1 and downregulation of tumor suppressor E-cadherin also occurs in the (pre)neoplastic state. This may contribute to the high potential for malignant degeneration of dysplasia in UC-related colitis.