Mesothelioma and internal carotid artery occlusion: acute ischemic stroke and efficacy of emergency carotid thrombectomy

Idiopathic thrombus in the common carotid artery on digital subtraction angiography

In the present study, we discuss the accuracy of digital subtraction angiography (DSA) in diagnosis of thrombus in the common carotid artery and its role in the medical management of this disorder. Between 2006 and 2011, four patients (age group ranging from 26 to 48 years) presented to our institution with symptoms of stroke. DSA in all these patients showed cigar-shaped filling defect in the common carotid artery. All the patients were managed successfully with anticoagulation treatment. Follow-up Duplex scan was done in all the patients. DSA is the gold standard to diagnose free floating thrombus in the common carotid artery. Medical management can be effective in these patients but a multidisciplinary team approach is needed for appropriate management.

Thrombomodulin is silenced in malignant mesothelioma by a poly(ADP-ribose) polymerase-1-mediated epigenetic mechanism

Malignant mesothelioma (MM) is often complicated by thromboembolic episodes, with thrombomodulin (TM) playing a critical role in the anticoagulant process. Heterogeneous expression of TM has been observed in cancer, and low or no TM expression in cancer cells is associated with poor prognosis. In this study, we analyzed TM expression in biopsies of MM patients and compared them with normal mesothelial tissue. The role of DNA methylation-associated gene silencing in TM expression was investigated. To evaluate poly(ADP-ribose) polymerase-1 (PARP1) as responsible for gene promoter epigenetic modifications, nonmalignant mesothelial cells (Met-5A) and MM cells (H28) were silenced for PARP1 and the DNA methylation/acetylation-associated TM expression evaluated. A correlation between low TM expression and high level of TM promoter methylation was found in MM biopsies. Low expression of TM was restored in MM cells by their treatment with 5-aza-2'-deoxycytidine and, to a lesser extent, with trichostatin, whereas the epigenetic agents did not affect TM expression in Met-5A cells. Silencing of PARP1 resulted in a strong down-regulation of TM expression in Met-5A cells, while restoring TM expression in H28 cells. PARP1 silencing induced TM promoter methylation in Met-5A cells and demethylation in MM cells, and this was paralleled by corresponding changes in the DNA methyltransferase activity. We propose that methylation of the TM promoter is responsible for silencing of TM expression in MM tissue, a process that is regulated by PARP1.