ABSTRACT
The BCR/ABL1 inhibitor Nilotinib is increasingly used to treat patients with chronic myeloid leukemia (CML). Although otherwise well-tolerated, Nilotinib has been associated with the occurrence of progressive arterial occlusive disease (AOD). Our objective was to determine the exact frequency of AOD and examine in vitro and in vivo effects of Nilotinib and Imatinib on endothelial cells to explain AOD-development. In contrast to Imatinib, Nilotinib was found to upregulate pro-atherogenic adhesion-proteins (ICAM-1, E-selectin, VCAM-1) on human endothelial cells. Nilotinib also suppressed endothelial cell proliferation, migration and tube-formation and bound to a distinct set of target-kinases, relevant to angiogenesis and atherosclerosis, including angiopoietin receptor-1 TEK, ABL-2, JAK1 and MAP-kinases. Nilotinib and siRNA against ABL-2 also suppressed KDR expression. In addition, Nilotinib augmented atherosclerosis in ApoE-/- mice and blocked reperfusion and angiogenesis in a hindlimb-ischemia model of arterial occlusion, whereas Imatinib showed no comparable effects. Clinically overt AOD-events were found to accumulate over time in Nilotinib-treated patients. After a median observation-time of 2.0 years, the AOD-frequency was higher in these patients (29.4%) compared to risk factor- and age-matched controls (<5%). Together, Nilotinib exerts direct pro-atherogenic and anti-angiogenic effects on vascular endothelial cells, which may contribute to development of AOD in patients with CML.
Subject(s)
Endothelium, Vascular/drug effects , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy , Protein Kinase Inhibitors/adverse effects , Pyrimidines/adverse effects , Vascular Diseases/chemically induced , Adult , Aged , Aged, 80 and over , Animals , Apolipoproteins E/genetics , Atherosclerosis/chemically induced , Endothelium, Vascular/cytology , Female , Humans , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Middle AgedABSTRACT
BACKGROUND: Apolipoprotein A5 (apoA5) is a recently described liver-specific protein that has been shown to influence triglyceride (TG) metabolism. ApoA5 transgenic mice display dramatically reduced TG levels, while in contrast apoA5 deficiency in humans was reported to result in marked hypertriglyceridemia. ApoA5 exerts its extracellular effects by increasing lipolysis of TG-rich lipoproteins, while in vitro data suggest additional intrahepatic effects. METHODS: In this study the authors set out to investigate a possible role of apoA5 in non-alcoholic fatty liver disease (NAFLD). We thus determined hepatic apoA5 expression in 15 obese subjects with histologically proven NAFLD undergoing bariatric surgery. In addition, the authors established a hepatic cell culture model of apoA5 knockdown by transfecting human hepatoma cells (HepG2) with apoA5 small interfering (si) RNA, and determined intracellular TG content and expression levels of key enzymes and transcription factors of intrahepatic lipid metabolism in these cells. RESULTS: Pronounced weight loss and associated histologically verified improvement of hepatic steatosis were accompanied by significant reductions of hepatic apoA5 mRNA expression levels. Significant apoA5 knockdown in HepG2 cells resulted in a marked decrease of intracellular TG content. When HepG2 cells were co-transfected with apoA5 and peroxisome proliferator-activated receptor gamma (PPARγ), reductions in hepatic TG accumulation were significantly less pronounced when compared to apoA5 siRNA transfected HepG2 cells. CONCLUSIONS: In obese subjects, hepatic apoA5 mRNA expression decreases after weight loss and improvements in hepatic steatosis. The authors' in vitro data demonstrate that apoA5 influences intrahepatic TG metabolism and that these intracellular effects of apoA5 are accompanied by changes in PPARγ mRNA expression. In summary, the data suggest that as well as several other factors, apoA5 might be involved in the pathogenesis of hepatic steatosis.
Subject(s)
Apolipoproteins A/physiology , Fatty Liver/metabolism , Adult , Anthropometry/methods , Apolipoprotein A-V , Apolipoproteins A/biosynthesis , Apolipoproteins A/genetics , Bariatric Surgery , Fatty Liver/etiology , Female , Gene Expression Regulation/physiology , Gene Knockdown Techniques , Humans , Lipid Metabolism/genetics , Liver/metabolism , Male , Middle Aged , Non-alcoholic Fatty Liver Disease , Obesity/complications , Obesity/metabolism , Obesity/surgery , PPAR gamma/biosynthesis , PPAR gamma/genetics , RNA, Messenger/genetics , RNA, Neoplasm/genetics , RNA, Small Interfering/genetics , Transfection , Triglycerides/metabolism , Tumor Cells, Cultured , Weight Loss/physiologyABSTRACT
BACKGROUND: Hepatic lipase plays a key role in the metabolism of pro-atherogenic and anti-atherogenic lipoproteins affecting their plasma level as well as their physico-chemical properties. We hypothesized single nucleotide polymorphisms in the promoter region of the hepatic lipase gene to be associated with an increased risk for peripheral arterial disease (PAD). METHODS: A total of 241 patients with PAD and 241 controls matched for sex and age (+/-2 years) were genotyped cross-sectionally for the --250 single nucleotide polymorphism in the hepatic lipase promoter. RESULTS. The frequency for the -250 A allele in patients with PAD was 0.203, whereas it was 0.147 in the controls (P=0.022). Hepatic lipase promoter polymorphism distribution remained significantly different between cases and controls after multivariate logistic regression analysis (P=0.021). The odds ratio of the -250 A hepatic lipase allele for the PAD was 1.69 (95% confidence interval of 1.08-2.64), when adjusted for current smoking, arterial hypertension, cholesterol, triglycerides, HbA(1C), total homocysteine and high sensitivity C-reactive protein. CONCLUSION: Previous data in patients with ischaemic heart disease have suggested a pro-atherogenic role of low hepatic lipase levels. Our results extend these data to the vascular territory of the lower limbs, such that hepatic lipase promoter variation represents a genetic risk factor of PAD.
Subject(s)
Lipase/genetics , Liver/enzymology , Peripheral Vascular Diseases/genetics , Polymorphism, Single Nucleotide , Promoter Regions, Genetic , Aged , Epidemiologic Methods , Female , Gene Frequency , Genetic Markers , Humans , Male , Middle Aged , Peripheral Vascular Diseases/enzymology , Polymerase Chain Reaction/methodsABSTRACT
To further elucidate the role of scavenger receptor class B type I (SR-BI) in reverse cholesterol transport and in atherogenesis, we performed studies in the rabbit, an animal model displaying a lipoprotein profile similar to that of human, expressing cholesteryl ester transfer protein in plasma and having been demonstrated to be susceptible to atherosclerosis. In this report, we describe for the first time the isolation and characterization of rabbit cDNA fragments encoding SR-BI and scavenger receptor class B type II (SR-BII). Development of an isoform-specific Taqman Real Time PCR system and generation of isoform-specific polyclonal antibodies allowed us to measure SR-BI and SR-BII expression in various rabbit organs on mRNA and protein levels, respectively. We found the highest expression of SR-BI in adrenal gland, liver, and proximal intestine; lesser expression was found in appendix and spleen. Immunohistochemical staining of frozen sections showed SR-BI expression in the cortex but not in the medulla of adrenal gland. An increasing portal to central vein gradient of expression was found within the hepatic lobule. As shown in this report, identification and characterization of SR-BI expression in the rabbit affords a powerful tool to elucidate the role of SR-BI in cholesterol homeostasis and atherogenesis in human.
