Polycomb group proteins (PcG), proteins that act to regulate transcription, have been implicated in numerous aspects of malignancies especially the ones with an aggressive phenotype and in stem cell biology. Misregulation of Polycomb protein levels often leads to either a block or unscheduled activation of developmental pathways, thereby enhancing the proliferation capability of a cell. Polycomb proteins form at least two distinct complexes, the Polycomb-repressive complexes 1 and 2 (PRC1 and PRC2). There is increasing evidence that PRC complexes have a role in tumor progression and development by blocking differentiation …

Many targeted agents, such as anti-VEGF and anti-EGFR blockers, have not shown promise against mesothelioma, at least when used as single agents. However these same targeted agents might be effective when used in combination with chemotherapy or when used in a selected subpopulation. This study tested a variety of targeted agents together with cisplatinum-pemetrexed against 4 mesothelioma lines and found vandetanib, an inhibitor of EGFR/VEGFR2/RET, to be the most effective. Although the agent has multiple effects (see figure), the effect seemed to be explained by the effect on EGFR and …

This article presents the results in humans of the first intrapleural instillation of a genetically modified cell line carrying a thymidine kinase suicide gene in mesothelioma.  From prior work, these instilled cells are thought to adhere to the intrapleural tumor and to form gap junctions.  Then, a pro-drug, ganciclovir, is delivered intravenously, diffuses into the pleural space and is converted by the TK gene in the cells to a toxic drug, ganciclovir-triphosphate, which kills the instilled cells and neighboring tumor cells via a ‘bystander effect’.  The process may also induce …

In this article, transcriptional deregulation, mediated by inactivation of the nuclear deubiquitinase BAP1, is implicated in the pathogenesis of mesothelioma.  The two most common known genetic alterations in mesotheliomas are 9p21 deletions on CDKN2A and 22q deletions causing NF2 loss. The authors show that another gene with a high rate of non-synonymous mutations is BAP1 (encoding BRCA1-associated protein 1).  Somatic mutations were found in 23% of mesotheliomas.  The study also shows that other common tumor suppressors, such as PTEN and p53, showed few or no mutations, confirming data from previous …