Chondrosarcoma is a primary bone tumor with a dismal prognosis; most patients with this disease develop fatal pulmonary metastases, suggesting the need for a better systemic treatment. Anti-angiogenesis treatment may be useful, because angiogenesis is critical for both tumor growth and metastasis. Vascular endothelial growth factor (VEGF) is the most potent pro-angiogenic factor and is regulated by pathways related to the normal physiologic response to hypoxia and genetic alterations related to the malignant phenotype. Our prior work has shown that VEGF is overexpressed in high grade chondrosarcoma and chondrosarcoma cell lines. Working on the premise that developmental pathways giving a selective growth advantage are often recapitulated in tumors, we investigated the regulation of VEGF by HDAC4 and Runx2 in chondrosarcoma. We tested the hypothesis that there is dysregulation of HDAC4/Runx2/VEGF gene expression and that decreased HDAC4 expression accounts for at least some of the increased VEGF expression seen in chondrosarcoma. We show that reduced expression of HDAC4 in chondrosarcoma cells increases expression of Runx2 leading to increased expression of VEGF and in vitro angiogenesis. Thus, both hypoxia and dysregulated expression of a developmental pathway are causes of increased VEGF expression in chondrosarcoma.Chondrosarcomas are mesenchymal tumors in which the primary tissue is cartilage; they include 20% of primary bone tumors and occur in patients of all ages (1, 2). Chondrosarcomas are difficult tumors to cure, because they are unresponsive to the standard adjuvant treatment, chemotherapy (3) and radiation therapy (4), resulting in cure rates of less than 10% (5, 6), with the vast majority of patients succumbing to pulmonary metastases. Angiogenesis is critical for both tumor growth and development of metastases, and inhibiting angiogenesis has become a therapeutic strategy. We have demonstrated that grade II and III chondrosarcomas have more microvascularity than benign or grade I tumors (7) and that these tumors overexpress vascular endothelial growth factor (VEGF) 2 (8).Because VEGF is the most important proangiogenic molecule and is overexpressed in high grade chondrosarcoma, we have focused on the regulation of VEGF in this tumor. VEGF expression is determined by normal physiologic hypoxia-related pathways and genetic abnormalities. We know that both of these broad categories of gene regulation are operational in chondrosarcomas. Included in genetic abnormalities are epigenetic phenomena such as DNA methylation and histone modification that regulate chromatin structure and gene expression (9). Both histone acetylases and histone deacetylases (HDACs) are key enzymes that catalyze the reversible acetylation/deacetylation of core histone tails, which is an essential mechanism of the epigenetic control of gene expression (10). HDACs function as transcriptional co-repressors. HDACs can deacetylate DNA binding transcription factors, thereby decreasing their binding affinity, localization, and half-life...

The cap-binding proteins CBP20 and CBP80 have well-established roles in RNA metabolism and plant growth and development. Although these proteins are thought to be involved in the plant's response to environmental stress, their functions in this process are unclear. Here we demonstrated that Arabidopsis cbp20 and cbp80 null mutants had abnormal leaves and flowers and exhibited increased sensitivity to salt stress. The aberrant phenotypes were more pronounced in the cbp20/80 double mutant. Quantification by iTRAQ (isobaric tags for relative and absolute quantification) identified 77 differentially expressed proteins in the cbp20 and cbp80 lines compared with the wild-type Col-0 under salt stress conditions. Most of these differentially expressed proteins were synergistically expressed in cbp20 and cbp80, suggesting that CBP20 and CBP80 have synergistic roles during the salt stress response. Biochemical analysis demonstrated that CBP20 and CBP80 physically interacted with each other. Further analysis revealed that CBP20/80 regulated the splicing of genes involved in proline and sugar metabolism and that the epigenetic and post-translational modifications of these genes were involved in salt stress tolerance. Our data suggest a link between CBP20/80-dependent protein ubiquitination/sumoylation and the salt stress response.

ZFP57 is a master regulator of genomic imprinting. It has both maternal and zygotic functions that are partially redundant in maintaining DNA methylation at some imprinting control regions (ICRs). In this study, we found that DNA methylation was lost at most known ICRs in Zfp57 mutant embryos. Furthermore, loss of ZFP57 caused loss of parent-of-origin–dependent monoallelic expression of the target imprinted genes. The allelic expression switch occurred in the ZFP57 target imprinted genes upon loss of differential DNA methylation at the ICRs in Zfp57 mutant embryos. Specifically, upon loss of ZFP57, the alleles of the imprinted genes located on the same chromosome with the originally methylated ICR switched their expression to mimic their counterparts on the other chromosome with unmethylated ICR. Consistent with our previous study, ZFP57 could regulate the NOTCH signaling pathway in mouse embryos by impacting allelic expression of a few regulators in the NOTCH pathway. In addition, the imprinted Dlk1 gene that has been implicated in the NOTCH pathway was significantly down-regulated in Zfp57 mutant embryos. Our allelic expression switch models apply to the examined target imprinted genes controlled by either maternally or paternally methylated ICRs. Our results support the view that ZFP57 controls imprinted expression of its target imprinted genes primarily through maintaining differential DNA methylation at the ICRs.

Abstract. Epigallocatechin gallate (EGCG), which is derived from green tea, is well known for its chemopreventive activity. Several studies have shown that p53 plays an important role in the activity of EGCG; however, the mechanism by which EGCG regulates p53 requires further investigation. In the present study, we showed that EGCG inhibits anchorage-independent growth of human lung cancer cells by upregulating p53 expression. EGCG treatment can substantially increase p53 stability, promote nuclear localization of p53 and decrease nuclear accumulation of MDM2. We also found that EGCG increases the phosphorylation of p53 at Ser15 and Ser20 and enhances its transcriptional activity. Although EGCG promotes MDM2 expression in a p53-dependent manner, the interaction between MDM2 and p53 was significantly inhibited following EGCG treatment, which resulted in the inhibition of MDM2-mediated p53 ubiquitination. Thus, our results suggest that the stabilization and activation of p53 may partly contribute to the anticancer activity of EGCG. IntroductionAccording to the results of epidemiologic studies, green tea consumption has a preventive effect on carcinogenesis (1-6). It is thought that polyphenols, also known as catechins, play an important role in the chemopreventive effects mediated by green tea. (-)-Epigallocatechin gallate (EGCG), a type of polyphenol, which is the most well known, abundant and active compound found in green tea, exerts its anticancer effects in a wide range of malignancies (2,7). Previous studies have suggested that multiple signaling pathways and mechanisms are involved in the antitumor activity of EGCG (1,8-10), including suppression of various protein kinases (11-13); disruption of the activation of transcription factors such as EGFR, NF-κB, AP-1 and STATs (14-16); induction of cell cycle arrest or apoptosis (17,18); and inhibition of cell migration and metastasis (19-24).p53, commonly referred to as the 'cellular gatekeeper' or 'the guardian of the genome', is a crucial tumor suppressor gene that is mutated in more than half of all types of human cancer. As a transcription factor, p53 functions to regulate cell fate following various types and levels of cellular stress through its downstream target genes. In addition to its canonical functions of inducing DNA repair, cell cycle arrest and apoptosis (25,26), recent studies have also revealed that p53 is involved in the regulation of various other cellular functions, such as senescence, metabolism and autophagy. Due to the importance of p53, its activation is regulated by complicated post-translational modifications, such as phosphorylation, acetylation, ubiquitination and sumoylation (8,(27)(28)(29). Previous studies have shown that the phosphorylation and acetylation of p53 promotes the expression of p53 target genes (28,30,31), whereas other modifications, such as ubiquitination and sumoylation, are considered to be associated with the suppression of p53-mediated transcription and nuclear export of p53 (32-34). MDM2, a Ring finger domain-con...