These results demonstrate that PPARgamma activators inhibit cardiac hypertrophy in cardiac myocytes and suggest that PPARgamma activators may regulate cardiomyocyte hypertrophy at least partially through the NF-kappaB pathway.

In the development of colorectal cancer (CRC), it is now widely accepted that some forms of genetic instability lead to the sequential accumulation of genetic alterations and consequently develop carcinomas. 1 RAS activation in the MAP kinase cascade is supposed to constitute a part of the primary events in colorectal carcinogenesis, and the KRAS gene mutations have been found in about 30 -40% cases of sporadic CRCs. [2][3][4] Recently, activating BRAF mutations have been found almost invariably in melanoma cells and sometimes in other types of carcinoma, including CRCs, 5-7 implying a function of BRAF as a protooncogene. The RAF genes are members of MAPK pathway, encoding serine/threonine kinases that integrate the upstream input signals. 8,9 Once recruited at the cell membrane by GTP-loaded RAS, RAF becomes activated and subsequently phosphorylates the downstream kinases, MEKs, which eventually induce transcriptional activation of the target genes. 9 More recently, frequent BRAF mutations and infrequent KRAS mutations have been reported in DNA-mismatch repair (MMR)-deficient CRCs. 10 Inactivation of MMR genes incurs instability of genomic microsatellite sequence (microsatellite instability, or MSI), which is found in the majority of patients with hereditary nonpolyposis colorectal cancer syndrome (HNPCC) and in 10 -15% of cases of sporadic CRCs. 11-13 Moreover, it was also reported that 70 -90% of sporadic CRCs with MSI (MSI ϩ CRCs) are associated with hypermethylation of hMLH1, one of DNA-MMR genes, and have distinct clinical and pathologic characteristics, i.e., occurrence in older females, location in the proximal colon and histopathology of mucious or poor differentiation. 14 -20 We have previously examined the methylation status of hMLH1 gene in sporadic CRCs by use of 5 sets of primer spanning the whole CpG sites within its promoter region and have classified the methylation status into 3 subtypes: full methylation, partial methylation and nonmethylation. 21,22 We reported that an extensive methylation, or full methylation, of hMLH1 promoter was found in about 80% of MSI ϩ CRC cases and was highly associated with loss of expression of its gene product. Interestingly, this type of CRC cells are rarely associated with KRAS mutations and loss of heterozygosity (LOH) of TP53 gene. 22 It is therefore possible that extensive methylation of hMLH1 promoter region may contribute to the carcinogenesis of the right-sided sporadic CRCs, independently of KRAS/p53 alterations.From these results, 2 questions may arise. First, does the activation of BRAF, instead of KRAS, take part in the carcinogenesis of CRCs with extensive hMLH1 methylation? Second, if so, does the BRAF activation have any relationship with the CRCs with partial methylation, although most of which are microsatellite stable (MSI Ϫ ), maintain MMR gene expression and show a relatively high incidence of KRAS and p53 alterations? 22 Additionally, in the melanoma cells, high frequency of mutations of ␤-catenin and BRAF has been recognized. 23 Some resea...

Abstract-Matrix metalloproteinase-1 (MMP-1), also called interstitial collagenase, may play an important role in the pathogenesis of atherosclerosis and atherosclerotic plaque rupture. We investigated the effects of fluvastatin on MMP-1 expression in human vascular endothelial cells (ECs). The addition of fluvastatin decreased the basal MMP-1 levels in the culture media of ECs in a time-dependent (0 to 48 hours) and dose-dependent (10 Ϫ8 to 10 Ϫ5 mol/L) manner. On the other hand, fluvastatin did not affect tissue inhibitor of metalloproteinase-1 levels. Collagenolytic activity in conditioned media of ECs was also dose-dependently reduced by fluvastatin. The effect of fluvastatin on MMP-1 expression was completely reversed in the presence of mevalonate or geranylgeranyl-pyrophosphate, but not in the presence of squalene. Key Words: atherosclerosis Ⅲ nitric oxide Ⅲ extracellular matrix Ⅲ collagen U nstable atherosclerotic plaque rupture is an important event that triggers acute coronary syndrome. Plaque rupture is frequently correlated with loss of the extracellular matrix at certain locations, often in the shoulder areas of the plaque. Focal destruction of the extracellular matrix renders the plaques less resistant to the mechanical stresses imposed during systole and therefore vulnerable to rupture. 1-3 Recent studies have suggested that matrix metalloproteinases (MMPs) may contribute to the vulnerability of atherosclerotic plaques by degrading the components of the fibrous cup: collagens, elastin, fibronectin, and proteoglycans. 4 Immunocytochemistry studies have demonstrated that MMP-1, MMP-9, and MMP-3 are expressed by cells present in atheromas, including luminal and neovascular endothelial cells, macrophages, and smooth muscle cells, but not by cells present in the walls of normal arteries. 5 Studies including in situ zymography and enzymatic activity assays showed a significantly enhanced collagenase activity in atherosclerotic plaques. 6 -8 The expression of MMP-1, also called interstitial collagenase, in atherosclerotic lesions warrants special attention because this enzyme is involved in the initial cleavage of collagens, mainly type I collagen. Type I collagen is the predominant protein in atherosclerotic plaques that confers strength to the fibrous cap. MMP-1 is also the only enzyme able to initiate the degradation of collagen at neutral pH.Hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) have been widely used for treatment of hyperlipidemia. They may also directly interfere with the major processes of atherogenesis occurring in the arterial wall. 9 Smooth muscle cell migration and proliferation are inhibited by HMG-CoA reductase inhibitors, 10,11 and cholesterol accumulation is prevented in macrophages by reducing modified-LDL endocytosis. 12 All of these cellular effects are mediated by inhibition of the isoprenoid pathway. If HMGCoA reductase inhibitors affect MMP activity, they could influence plaque stability and disease progression of coronary artery diseases. Recently,...

Summary. Myelodysplastic syndrome (MDS) is a clonal disorder of haematopoietic stem cells. Despite the high incidence of MDS in the elderly, effective treatment of individuals in its advanced stages is problematic. DNA microarray analysis is a potentially informative approach to the development of new treatments for MDS. However, a simple comparison of 'transcriptomes' of bone marrow mononuclear cells among individuals at distinct stages of MDS would result in the identification of genes whose expression differences only reflect differences in the proportion of MDS blasts within bone marrow. Such a 'population shift' effect has now been avoided by purification of haematopoietic stem-like cells that are positive for the cell surface marker AC133 from the bone marrow of healthy volunteers and 30 patients at various stages of MDS. Microarray analysis with the AC133 + cells from these individuals resulted in the identification of sets of genes with expression that was specific to either indolent or advanced stages of MDS. The former group of genes included that for PIASy, which catalyses protein modification with the ubiquitin-like molecule SUMO. Induction of PIASy expression in a mouse myeloid cell line induced apoptosis. A loss of PIASy expression may therefore contribute directly to the growth of MDS blasts and stage progression.