BAP1‐deficient and VE1‐negative atypical Spitz tumor

Atypical Spitz tumor with loss of BAP1 or Wiesner nevus is a peculiar variant of intradermal spitzoid melanocytic neoplasm composed of epithelioid melanocytes with a sheet‐like growth pattern, abundant infiltrating lymphocytes and rare or absent mitotic activity. This subset of atypical spitzoid tumors is characterized by the BRAF^V600E mutation and loss of BAP1 expression. Recognition of these lesions is important because they can be a marker for a hereditary BAP1‐associated cancer syndrome. We present an unusual case of sporadic Wiesner nevus that had typical histopathologic features and a BAP1 but not a BRAF mutation. The biological significance of Wiesner nevus is controversial, and little is known about prognosis, particularly in atypical cases like this one.     

Cellular senescence, cancer and aging: the telomere connection

Telomeres are the repetitive DNA sequences and specialized proteins that form the distinctive structure that caps the ends of linear chromosomes. Telomeres allow cells to distinguish the chromosome ends from double strand DNA breaks. The telomeric structure prevents the degradation or fusion of chromosome ends, and thus is essential for maintaining the integrity and stability of eukaryotic genomes. In addition, and perhaps less widely appreciated, telomeres may also indirectly influence gene expression. The length, structure and organization of telomeres are regulated by a host of telomere-associated proteins, and can be influenced by basic cellular processes such as cell proliferation, differentiation, and DNA damage. In mammalian cells, telomere length and/or telomere structure have been linked to both cancer and aging. Here, we briefly review what is known about mammalian telomeres and the proteins that associate with them, and discuss the cellular and organismal consequences of telomere dysfunction and the evidence that cells with dysfunctional telomeres can contribute to cancer and aging phenotypes.     

COL11A1 in FAP polyps and in sporadic colorectal tumors

Background  

We previously reported that the α-1 chain of type 11 collagen (COL11A1), not normally expressed in the colon, was up-regulated in stromal fibroblasts in most sporadic colorectal carcinomas. Patients with germline mutations in the APC gene show, besides colonic polyposis, symptoms of stromal fibroblast involvement, which could be related to COL11A1 expression. Most colorectal carcinomas are suggested to be a result of an activated Wnt- pathway, most often involving an inactivation of the APC gene or activation of β-catenin.