Ancient cardiac myxomas - another point of view in the light of tetraspanins.

Myxomas are the most common non-invasive but life-threatening cardiac neoplasms due to obstruction of heart chambers and risk of embolism in a manner resembling thromboembolism as well. They can occasionally disseminate via their detached fragments into the bloodstream to seed and grow as secondary still benign tumors. In this study we evaluated morphological and clinical aspects of 14 ancient, degenerated left or right-sided cardiac atrial myxomas with expression of CD9 and CD63, which are found to contribute to platelet activation, aggregation and, as a result, intratumoral thrombosis or fragmentation. The appearance of tumors varied from sessile to polypoid revealing that a higher rate of endocardial thrombosis was associated with sessile compared to polypoid myxomas and left-sided tumors compared to right-sided ones in our study. In the general aspect of ancient calcifications, amorphous calcification with intra-tumor thrombosis was noted more frequently in sessile tumors, while well-formed osseous metaplasia was usually a feature of polypoid tumors. In our material osseous metaplasia did not coexist with massive thrombosis and was found in polypoid, pedunculated myxomas. Most importantly, CD9 overexpression was recorded in every studied myxoma and CD63 gave a weak reaction in myxoma cells.

N-cadherin, beta-catenin and connexin 43 expression in astrocytic tumours of various grades.

INTRODUCTION: Astrocytic tumors are the most common primary brain tumors, but little is known about their etiology and prognostic factors. N-cadherin and beta-catenin are adhesive proteins, and are often overexpressed in many types of cancers, including breast or colorectal cancer, resulting in better prognosis. Connexin 43 is a gap junction protein involved in cell-cell signaling pathway taking part in the process of carcinogenesis. The aim of the study was to evaluate N-cadherin, beta-catenin and connexin 43 expression in astrocytic tumors of various grades. MATERIALS AND METHODS: We examined 131 cases of astrocytic tumors, including 26 cases of diffuse astrocytoma (group I), 44 anaplasic astrocytomas (group II) and 61 glioblastoma cases (group III)--primary and secondary. To evaluate N-cadherin, beta-catenin and connexin 43 expression, we used immunohistochemical reaction with specific antibodies (Santa Cruz Biotechnology). The obtained results were correlated with clinical and morphological features. RESULTS: Beta-catenin expression was observed in 69.3% of diffuse astrocytomas, 75% of anaplastic astrocytomas, and 82% of glioblastoma cases. N-cadherin expression was observed in 92.3% of diffuse astrocytomas, 90.1% of anaplastic astyrocytomas, and in all glioblastoma cases. Connexin 43 was observed in 76.9% of diffuse astrocytomas, and in all cases of anaplastic astrocytomas and glioblastomas. Beta-catenin expression was significant within the nucleus of neoplastic cells in groups I and II. In group III, staining was observed only in the cellular membranes. N-cadherin and connexin 43 expression was observed only in the cells' membranes. In glioblastomas, both primary and secondary, all protein expression was significant within the cells surrounding the necroses and blood vessels and weak or absent in the tumor's margins. CONCLUSION: Our study shows that beta-catenin nuclear expression in group of diffuse astrocytomas and anaplastic astrocytomas is evidence for transcriptional function of beta-catenin in those groups. Strong N-cadherin and connexin 43 expression in those groups may be evidence for their role in tumor formation and progression. However, in glioblastomas a very important role of all examined proteins is generating intracellular connections to facilitate the escape of tumor cells from the effects of hypoxia or their accumulation around the blood vessels rather than tumor invasion into the brain parenchyma.