Histology and histopathology Vol.22, nº12 (2007)

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Oxidative damage in age-related macular degeneration
(Murcia: F. Hernández, 2007) Shen, J.K.; Dong, A.; Hackett, S.F.; Bell, W.R.; Green, W.R.; Campochiaro, P.A.
Epidemiologic studies have suggested that elderly patients who consumed diets rich in antioxidants throughout their lives are less likely to be afflicted with age-related macular degeneration (AMD). This led to the Age-Related Eye Disease Study, which showed that supplements containing antioxidant vitamins and zinc reduce the risk of progression to severe stages of AMD. Despite these data that indirectly implicate oxidative damage in the pathogenesis of AMD, there has not been any direct demonstration of increased oxidative damage in the retinas of patients with AMD. In this study, we used biomarkers of oxidative damage in postmortem eyes from patients with AMD and comparably aged patients without AMD to directly assess for oxidative damage. Sections from 4 eyes with no pathologic features of AMD showed no immunofluorescent staining for markers of oxidative damage, while sections from 8 of 12 eyes with advanced geographic atrophy showed evidence of widespread oxidative damage in both posterior and anterior retina. Only 2 of 8 eyes with choroidal neovascularization and 2 of 16 eyes with diffuse drusen and no other signs of AMD showed evidence of oxidative damage. These data suggest that widespread oxidative damage occurs in the retina of some patients with AMD and is more likely to be seen in patients with advanced geographic atrophy. This does not rule out oxidative damage as a pathogenic mechanism in patients with CNV, but suggests that a subpopulation of patients with geographic atrophy may have a major deficiency in the oxidative defense system that puts the majority of cells in the retina at risk for oxidative damage.
Open Access
Primary hepatic malignant fibrous histiocytoma: A case report and review of the literature
(Murcia: F. Hernández, 2007) Ye, M-F.; Zheng, S.; Xu, J.H.; Chen, L-R.
Primary malignant fibrous histiocytoma (MFH) of the liver remains extremely rare with only several cases having been reported in literature. We report a case of hepatic MFH in a 53-year-old man who presented with upper abdominal pain, and weight loss for one month. Ultrasound and computed tomography (CT) scan showed a large mass with fine tumor vessels over the left lobe of the liver. Histopathological findings indicated a mesenchymal tumor consisting of spindle cells in storiform pattern intermingled with histiocytelike cells and giant cells. Immunohistochemically, most tumor cells expressed vimentin, alpha-1 antichymotrypsin, alpha-1 antitrypsin and CD68. Morphological and immunohistochemical findings support that the tumor should be classified as a primary malignant fibrous histiocytoma. The literatures is briefly reviewed.
Open Access
Standardization of an orthotopic mouse brain tumor model following transplantation of CT-2A astrocytoma cells
(Murcia: F. Hernández, 2007) Martínez Murillo, R.; Martínez, A.
Animal models of glial-derived neoplasms are needed to study the biological mechanisms of glioma tumorigenesis and those that sustain the disease state. With the aim to develop and characterize a suitable in vivo experimental mouse model for infiltrating astrocytoma, with predictable and reproducible growth patterns that recapitulate human astrocytoma, this study was undertaken to analyze the long-term course of a syngeneic orthotopically implanted CT-2A mouse astrocytoma in C57BL/6J mice. Intracranial injection of CT-2A cells into caudate-putamen resulted in development of an aggressive tumor showing typical features of human glioblastoma multiforme, sharing close histological, immunohistochemical, proliferative, and metabolic profiles. To simulate metastatic disease to the brain, CT-2A cells were injected through the internal carotid artery. Tumors identical to those obtained by intracranial injection were obtained. Finally, CT-2A cells were re-isolated from experimental brain tumors and transcranially re-injected into the caudate-putamen of healthy mice. These cells generated new tumors that were indistinguishable from the initial ones, suggesting in vivo self-renewal of tumor cells. Small-animal models are essential for testing novel biological therapies directed against relevant molecular targets. In a preliminary study, experimental CT-2A tumors were chronically treated with the small molecule 77427, a gastrin-releasing peptide (GRP) blocker compound that inhibits angiogenesis. Treated animals developed significantly smaller tumors than controls, suggesting an antitumor action for 77427 in glioblastomas. We conclude that the orthotopic CT-2A tumor model, as described herein, is appropriate to explore the mechanisms of glioma development and for preclinical trials of promising drugs.
Open Access
Epigenetic remodelling of DNA in cancer
(Murcia: F. Hernández, 2007) Lettini, A.A.; Guidoboni, M.; Fonsatti, E.; Anzalone, L.; Cortini, E.; Maio, M.
DNA methylation regulates gene expression in normal cells. This epigenetic mechanism acts in at least two different ways: at global genomic level by targeting repetitive sequences distributed among the whole genome (LINEs, SINEs, satellite DNA, transposons) and at local level by targeting CpG islands in promoter regions. Both epigenetic mechanisms are involved in the carcinogenetic process; however, different evidences suggest that promoter hypermethylation occurring in genes involved in cellcycle regulation, DNA repair, cell signalling, transcription and apoptosis likely plays a prominent role. Opposite to genetic defects DNA hypermethylation is a reversible process that can be handled through “epigenetic drugs” in a wide spectrum of tumors. Along this line, recent data have demonstrated the ability of DNA hypomethylating agents to up-regulate and/or induce the expression of genes silenced by promoter hypermethylation in cancer. Particularly relevant seems the ability of these drugs to modulate the expression of genes coding for molecules crucial for tumor immunogenicity and immune recognition of neoplastic cells by host’s immune system, such as Cancer Testis Antigens, HLA class I molecules, costimulatory molecules. These evidences, coupled to the well-known cytotoxic, pro-apoptotic, and differentiating activities of epigenetic drugs, encourage to design and to develop new therapeutic strategies able to circumvent the immune escape of neoplastic cells and to potentiate the efficacy of immunotherapy in cancer patients. This review will provide an update on the most recent information about aberrant DNA methylation in cancer and on innovative therapeutic strategies of “epigenetic remodelling” of human malignancies, with particular attention to the immunologic and immunotherapeutic potential of this approach.
Open Access
Apoptosis in peripheral neuroblastic tumors. Immunohistochemical expression of bcl-2 and p53 is related to DNA fragmentation
(Murcia: F. Hernández, 2007) Mejía, C.; Navarro, S.; Llombart-Bosch, A.
We examined 111 cases of neuroblastoma (NB), searching for how NB relates to apoptotic control and other prognostic factors. Immunohistochemistry using avidin-biotin-peroxidase was carried out for bcl-2 and p53 proteins. Apoptosis was analyzed by in situ detection of chromosomal breakdown. DNA ladders were detected by electrophoresis and amplification of MYCN was carried out by PCR and Southern blot. Statistical analyses were performed with Pearson’s c2 and Kruskal-Wallis tests and Cox’s regression. We found expression of bcl-2 protein mainly in cases of neuroblastoma without differentiation and in stages 3 and 4. Expression of p53 protein showed a correlation with bcl-2 and the apoptotic phenomenon; apoptosis was found mainly in favorable cases. Multivariate analysis showed bcl-2 protein expression to be the most independent risk factor. The study of apoptosis could be important for the design of therapies to treat neuroblastoma.

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