Cell Cycle Arrest and Apoptosis Induction Activity of Nitidine Chloride on Acute Myeloid Leukemia Cells.

BACKGROUND: Acute myeloid leukemia (AML) is the most common hematological malignancy in adults, characterized by distorted proliferation and development of myeloid cells and their precursors in the bone marrow. Nitidine chloride, a naturally occurring alkaloid, has been identified to possess antitumor activity. However, the effects of nitidine chloride on acute myeloid leukemia cells and its underlying mechanisms have not been elucidated. Here we investigated the cellular and molecular mechanism of the anti-leukemic effects of nitidine chloride. METHODS AND RESULTS: Nitidine chloride treatment for 48 consecutive hours exhibited a timedependent and dose-dependent growth inhibition activity against AML cells by inducing cell cycle arrest and apoptosis. Moreover, nitidine chloride downregulated Cyclin B1, CDK1 and Bcl-2, upregulated p27 and Bax, inactivated PARP, activated Caspase-3 in AML cells. We further demonstrated that growth inhibition activity of nitidine chloride in AML cells is partially via inhibiting the phosphorylation of AKT and ERK. CONCLUSION: In conclusion, our data suggest that nitidine chloride could be an effective therapeutic agent against AML via cell cycle arrest and apoptosis.

Familial aggregation of albuminuria and arterial hypertension in an Aboriginal Australian community and the contribution of variants in ACE and TP53.

BACKGROUND: Aboriginal Australians are at high risk of cardiovascular, metabolic and renal diseases, resulting in a marked reduction in life expectancy when compared to the rest of the Australian population. This is partly due to recognized environmental and lifestyle risk factors, but a contribution of genetic susceptibility is also likely. METHODS: Using results from a comprehensive survey of one community (N = 1350 examined individuals), we have tested for familial aggregation of plasma glucose, arterial blood pressure, albuminuria (measured as urinary albumin to creatinine ratio, UACR) and estimated glomerular filtration rate (eGFR), and quantified the contribution of variation at four candidate genes (ACE; TP53; ENOS3; MTHFR). RESULTS: In the subsample of 357 individuals with complete genotype and phenotype data we showed that both UACR (h2 = 64%) and blood pressure (sBP h2 = 29%, dBP, h2 = 11%) were significantly heritable. The ACE insertion-deletion (P = 0.0009) and TP53 codon72 polymorphisms (P = 0.003) together contributed approximately 15% of the total heritability of UACR, with an effect of ACE genotype on BP also clearly evident. CONCLUSIONS: While the effects of the ACE insertion-deletion on risk of renal disease (especially in the setting of diabetes) are well recognized, this is only the second study to implicate p53 genotype as a risk factor for albuminuria - the other being an earlier study we performed in a different Aboriginal community (McDonald et al., J Am Soc Nephrol 13: 677-83, 2002). We conclude that there are significant genetic contributions to the high prevalence of chronic diseases observed in this population.

Differential bone marrow stem cell mobilization by G-CSF injection or arterial ligation in baboons.

Bone marrow stem cells (BMSCs) are mobilized in response to ischemic attacks, e.g. myocardial infarction, to repair the damage, or by cytokines, e.g. granulocyte colony-stimulating factor (G-CSF), which is used to harvest BMSCs for autologous transplantation. In order to optimize BMSC mobilization strategy for cardiovascular repair, we investigated whether BMSCs mobilized by G-CSF share the same subtype profile as that by ischemia in a non-human primate model. We subjected five baboons to subcutaneous G-CSF injection and five baboons to femoral artery ligation. Blood BMSCs were measured by surface antigens; functional differentiation to endothelial cells (ECs) was assessed by colony-forming capacity, expression of mature EC antigens and tube-like formation. The number of circulating CD34+/CD45RA- cells spiked on day 3 post-stimulation in both groups. While the number of CD34+ cells released by artery ligation was 2-fold lower by comparison with the number released by G-CSF administration, significantly more CD133+/KDR+/CXCR4+/CD31+ cells were detected in the baboons that underwent artery ligation. After culture in endothelial growth medium, mononuclear cells from baboons with artery ligation formed more EC colonies and more capillary-like tubes (P < 0.05), expressed higher vWF and phagocytosed more Dil-Ac-LDL (P < 0.05). While G-CSF and artery ligation can mobilize BMSCs capable of differentiating into ECs, BMSCs mobilized by the artery ligation simulating in vivo ischemic attacks have higher potential for vascular differentiation. Our findings demonstrate that different mobilization forces release different sets of BMSCs that may have different capacity for cardiovascular differentiation.

Endothelial senescence after high-cholesterol, high-fat diet challenge in baboons.

Increasing evidence indicates that replicative senescence and premature endothelial senescence could contribute to endothelial dysfunction. This study aims at testing the hypothesis that a high-fat diet may lead to premature vascular endothelial senescence in a nonhuman primate model. We isolated endothelial cells from left and right femoral arteries in 10 baboons before and after a 7-wk high-fat dietary treatment. We compared the morphological alterations, replicative capacities, and senescence-associated beta-galactosidase activities (SA-beta-gal) at these two time points. We found that high-fat diet increased the prevalence of endothelial senescence. Endothelial replicative capacities declined dramatically, and SA-beta-gal activities increased significantly in postdietary challenge. There was no change in telomeric length using quantitative flow fluorescence in situ hybridization analysis, suggesting that some stressors lead to cell senescence independent of telomere dysfunction. Our findings that high-fat diet causes endothelial damage through the premature senescence suggest a novel mechanism for the diet-induced endothelial dysfunction.

Obesity, Type II diabetes and the beta 2 adrenoceptor gene Gln27Glu polymorphism in the Tongan population.

As there is a high prevalence of obesity in Tonga, we aimed to determine the distribution of the beta2 adrenoceptor gene Gln(27)Glu polymorphism and to assess its relevance to obesity and to Type II diabetes, known to be prevalent in that population. A random sample of 1022 individuals from Tonga were genotyped for the Gln(27)Glu polymorphism in the beta 2 adrenoceptor gene. To assess the prevalence of obesity we measured body-mass index (BMI), fat-free mass, percentage fat and waist-to-hip ratio (WHR). To assess glucose metabolism we measured HbA(1c), fasting blood glucose, fasting serum insulin, and 1- and 2-h glucose; we also measured serum lipid and creatinine levels. We found that 84% of the Tongan men and 93% of the women were overweight or obese (BMI > or = 25 kg/m(2)) and 15.1% had Type II diabetes. Genotype frequencies among the 1022 Tongans were: Gln/Gln 90.3% and Gln/Glu 9.6%; we found one Glu/Glu homozygote. The mean BMI (+/-S.D.) for men was not significantly different for those who were homozygous (30.2+/-5.4 kg/m(2)) or heterozygous (30.1+/-5.5 kg/m(2)) for the Gln allele; this was also true for women (33.7+/-6.2 kg/m(2) for homozygous and 34.0+/-5.6 kg/m(2) for heterozygous). The Glu allele was not associated with other measures of obesity or abnormal glucose metabolism in this generally overweight population. There is a unique frequency of the Gln/Glu beta 2 adrenoceptor polymorphism among Tongans. We found no association of the polymorphism with obesity measures or Type II diabetes-related variables in the Tongan population among whom we documented a high prevalence of obesity and Type II diabetes and a low frequency of the Glu allele.

The p53Pro72Arg polymorphism is associated with albuminuria among aboriginal Australians.

Albuminuria is a widely recognized marker of renal disease and cardiovascular risk. This is especially true in Aboriginal Australians living in remote communities who suffer high rates of end-stage renal disease and cardiovascular mortality. During a survey of risk factors for renal and cardiovascular disease in one such community, an association between a common polymorphism at codon 72 (Arg/Pro) of the p53 gene and markers of renal disease was sought. A cross-sectional community survey including 217 people was performed. Genotypes of the polymorphism were distributed in Hardy-Weinberg equilibrium, with p53Arg allele frequency of 0.45 (range, 0.41 to 0.50). Overall prevalence of albuminuria was high (31% microalbuminuria; 14% overt albuminuria). Urine albumin/creatinine ratio (ACR) was significantly associated with the number of p53Pro alleles (P = 0.01), and there was an interaction with tobacco smoking (P = 0.04). The p53 genotype was also associated with increasing HbA1c, but the relationship between p53 and ACR was independent of this. This is a previously unreported association. This study does not address the mechanism, but this finding, if confirmed, expands the described effects of p53 in cellular proliferation and apoptosis to include a role in the course of renal and possibly cardiovascular disease in this population.