No abstract

Direct invasion from proliferating basaloid atypical keratinocytes limited to the epidermal basal layer (AK I), known as the differentiated pathway, was the most common form of progression to cutaneous iSCC in our series. On the other hand, stepwise progression from AK I to AK II and AK III (classic pathway) was seen to be operative in a substantial proportion of iSCC cases. All AK lesions, irrespective of intraepidermal neoplasia thickness, are therefore potentially invasive and tumour advance along adnexal structures might facilitate iSCC development from AK I lesions.

e One of the most striking epigenetic alterations that occurs at the level of the nucleosome is the complete exchange of the canonical H2A histones for the macroH2A variant. Here, we provide insight into the poorly recognized function of macroH2A in transcriptional activation and demonstrate its relevance in embryonic and adult stem cells. Knockdown of macroH2A1 in mouse embryonic stem (mES) cells limited their capacity to differentiate but not their self-renewal. The loss of macroH2A1 interfered with the proper activation of differentiation genes, most of which are direct target genes of macroH2A. Additionally, macroH2A1-deficient mES cells displayed incomplete inactivation of pluripotency genes and formed defective embryoid bodies. In vivo, macroH2A1-deficient teratomas contained a massive expansion of malignant, undifferentiated carcinoma tissue. In the heterogeneous culture of primary human keratinocytes, macroH2A1 levels negatively correlated with the self-renewal capacity of the pluripotent compartment. Together these results establish macroH2A1 as a critical chromatin component that regulates the delicate balance between self-renewal and differentiation of embryonic and adult stem cells.

Primary neuroendocrine carcinoma of the skin, or Merkel cell carcinoma, is the most aggressive cutaneous neoplasm. In spite of its similarities to small cell carcinomas from other locations, Merkel cell carcinoma shows many peculiarities probably related to its epidermal origin and the etiologic role of UV radiation. We have immunohistochemically investigated 43 markers on a tissue microarray in which 31 surgically resected Merkel cell carcinomas were represented. Of these, 15 patients remained free of disease after removal, whereas 16 developed metastases. Immunoreactivity was scored according to staining intensity and the percentage of positive cells. We found statistically significant correlations between metastatic tumor spread and overexpression of matrix metalloproteinase (MMP) 7, MMP10/2, tissue inhibitor of metalloproteinase 3, vascular endothelial growth factor (VEGF), P38, stromal NF-kappaB, and synaptophysin. Also detected were statistically significant correlations between the expression levels of MMP7 and VEGF, MMP7 and P21, MMP7 and P38, MMP10/2 and VEGF, P38 and synaptophysin, P38 and P53, and P21 and stromal NF-kappaB. These findings may be helpful in predicting the clinical course of Merkel cell carcinoma and are potentially useful for the development of targeted therapies.

Background: Condensin SMC proteins are frequently overexpressed in WNT-activated hyperplastic cells. Results:The SMC2 promoter is a novel target on the ␤-catenin⅐TCF4 transcription complex. Conclusion: ␤-Catenin⅐TCF4 may drive production of condensin in hyperplastic cells. SMC2 is required to ensure cellular mitosis and fast proliferation. Significance: Down-regulation of SMC2 expression can repress cell proliferation in WNT-activated cells and represents a new therapeutic target in cancer treatment.

GISTs can arise anywhere in the gastrointestinal tract and present a great variety of clinical and radiologic features, depending mostly on size and location.

Brown tumors (BT) are benign focal bone lesions that may appear in the context of primary and secondary hyperparathyroidism (HPT). Involvement of the spine is exceedingly rare. We present a case of brown tumor involving the cervical spine, the third reported in the literature. In the literature review (until August 2010), we found nine cases of spinal BT in primary HPT and 14 cases in secondary HPT. Fifteen patients (65%) had evidence of spinal cord compression. A 34-year-old woman on long-term hemodialysis, with secondary HPT, presented with a 9-month history of persistent neck pain. Radiographs of the cervical spine revealed an expansive osteolytic lesion in the posterior arch of the second cervical vertebra. MR imaging revealed an expansive mass on C2 affecting the vertebral body, odontoid process, right pedicle, laminas, and spinous process; there were no signs of spinal edema. A CT-guided needle biopsy of the lesion showed destruction of trabecular bone, infiltration of the fibroblastic cells, and abundant osteoclast-like multinucleated giant cells with hemorrhage and hemosiderin pigment, and the diagnosis of brown tumor was made. Cervical pain disappeared within a few days of parathyroidectomy, and rapid remineralization of C2 was evident within a few months. BT must always be considered in the context of hyperparathyroidism and osteolytic lesions. Vertebral BT can be particularly devastating due to medullar compression symptoms. Regression or complete disappearance of these lesions after parathyroidectomy is common, but prompt surgical decompression is necessary in case of medullar compression symptoms.

Peptidyl arginine deiminases (PADI) are a family of enzymes that catalyze the poorly understood posttranslational modification converting arginine residues into citrullines. In this study, the role of PADIs in the pathogenesis of colorectal cancer was investigated. Specifically, RNA expression was analyzed and its association with survival in a cohort of 98 colorectal cancer patient specimens with matched adjacent mucosa and 50 controls from donors without cancer. Key results were validated in an independent collection of tumors with matched adjacent mucosa and by mining of a publicly available expression data set. Protein expression was analyzed by immunoblotting for cell lines or IHC for patient specimens that further included 24 cases of adenocarcinoma with adjacent dysplasia and 11 cases of active ulcerative colitis. The data indicate that PADI2 is the dominantly expressed PADI enzyme in colon mucosa and is upregulated during differentiation. PADI2 expression is low or absent in colorectal cancer. Frequently, this occurs already at the stage of low-grade dysplasia. Mucosal PADI2 expression is also low in ulcerative colitis. The expression level of PADI2 in tumor and adjacent mucosa correlates with differential survival: low levels associate with poor prognosis.Implications: Downregulation of PADI2 is an early event in the pathogenesis of colorectal cancer associated with poor prognosis and points toward a possible role of citrullination in modulating tumor cells and their microenvironment.