Expression of a Nitric Oxide Synthesizing Protein in Arterial Endothelial Cells in Response to Different Anti-Anginal Agents Used in Acute Coronary Syndromes

BACKGROUND

Organic "nitro" compounds such as nitroglycerine, isosorbide dinitrate are useful in the control of chest pain in acute coronary syndrome. But the mechanism of it in pain regulation remains speculative. Here, increase of NO production was investigated by the possible regulation of constitutive nitric oxide synthase (cNOS) function from goat arterial endothelial cells. This protein was purified and sequence wise characterized as protein disulfide isomerase (PDI) in response to different nitro compounds.

METHOD

The NO generating protein was isolated from arterial endothelial cells and prepared to homogeneity. NO was determined by methemoglobin method. Protein sequence was analyzed by (µLC/MS/MS).

RESULTS

A protein of Mr. ~57 kDa was isolated and found to be activated by not only "nitro" compounds but also by acetyl salicylic acid, insulin and glucose. The global BLAST of the protein sequence showed a significant alignment of the protein sequence with PDI. This protein trivially called pluri activator stimulated endothelial NOS (PLASENOS). The enzyme was stimulated by the above-mentioned activators in the presence of Ca2+. Lineweaver-Burk plot of this NOS like activities were demonstrated with its specific substrate l-arginine as Vmax = 5(nmol NO/mg of protein/hr) and Km≈ 0.5µM by the above activators. The enzyme activity was inhibited by the l-NAME, the specific inhibitor of NOS.

CONCLUSION

The organic nitro compounds, acetyl salicylic acid, insulin and glucose were found to activate PLASENOS in the arterial endothelial cells for a continuous supply of NO to control the chest pain in acute coronary syndrome.

Restoration by aspirin of impaired plasma maspin level in human breast cancer

Maspin, an anti breast cancer protein, is produced in the normal mammary cells but not in malignant cells in breast cancer. We investigated the effect of aspirin induced increase of plasma nitric oxide (NO) on plasma maspin production in breast cancer patients. Fifteen breast cancer patients (35-65 years), who had not yet undergone any cancer therapy, and an equal number of age matched normal female volunteers participated in the study. They were asked not to take any medication for two weeks. All participants then ingested 150 mg of aspirin. Plasma NO and maspin levels were determined before and at 60 min after the ingestion of aspirin. It was found that the maspin level in plasma increased to 4.63+/-0.02 nM from the basal 0.95+/-0.012 nM (p<0.001) with increase of plasma NO from 0.60+/-0.03 microM to 2.08+/-0.030 microM (p<0.001) in breast cancer patients. In normal volunteers the basal maspin increased from 4.76+/-0.041 to 9.36+/-0.036 nM (p<0.001) with increase of NO from 2.15+/-0.08 to 3.36+/-0.04 microM (p<0.001) at the same period. These results indicated that the ingestion of aspirin might be beneficial for breast cancer through increased maspin production.

Systemic production of IFN-alpha by garlic (Allium sativum) in humans

The effect of foods on the production of interferon-alpha (IFN-alpha) is currently unknown. Garlic (Allium sativum) used as a folk medicine is reported to stimulate nitric oxide (NO) production. We investigated the systemic increase of NO due to the ingestion of garlic on the plasma IFN-alpha level in normal volunteers. Normal volunteers (10 groups, 10 in each group) ate 2 g fresh garlic, and plasma NO and IFN-alpha levels were determined after 2 and 4 h. The participants were also asked to eat garlic for various periods of time, and plasma NO and IFN-alpha were similarly assayed. Ingestion of 2 g fresh, but not boiled, garlic was found to increase the basal plasma level of NO from 2.7 +/- 0.1 microM to 8.76 +/- 0.21 microM at 2 and 4 h, respectively. The basal plasma IFN-alpha level increased from 9.51 +/- 0.26 nM to 46.3 +/- 1.2 nM in normal volunteers (n = 10) at the same time. The chronic eating of garlic was found to maintain IFN-alpha at high levels for at least 7 days. The exposure of neutrophils to garlic in vivo or in vitro, which also stimulated synthesis of NO in these cells, was found to stimulate IFN-alpha synthesis as measured by the stimulation of IFN-alpha mRNA synthesis. Thus, consumption of garlic resulted in stimulated synthesis of NO and, in turn, IFN-alpha in humans, which could be beneficial in viral or proliferative diseases.

The role of insulin dependent NO synthesis in the impaired production of maspin in human breast cancer

PURPOSE

The synthesis of maspin, a protein with various anti-breast cancer properties has been reported to be produced in normal breast tissue but not in breast cancer cells. We investigated the role of insulin receptors and their upregulation by prostaglandin E(1) in vitro for the stimulation of NO synthesis by the hormone, and its consequence on maspin production in normal neutrophils and malignant cells in breast cancer.

METHODS

Maspin and NO were determined by ELISA and methemoglobin method, respectively.

RESULTS

The treatment of neutrophils and malignant breast cancer cells with prostaglandin E(1) resulted in partial restoration of the impaired receptor numbers, and resulted in partial normalization of NO and maspin production in these cells compared to normal counterparts. It was not feasible to stimulate NO synthesis to normal ranges by the upregulation of receptor number due to intrinsic decrease of insulin receptors in breast cancer cells. However, aspirin, which was found to stimulate NO synthesis to normal ranges, normalized maspin production in these cells in breast cancer.

CONCLUSION

The impaired maspin production was found to be the consequence of impaired insulin induced NO production in breast cancer due to the decrease of insulin receptor binding. Restoration of NO production by aspirin can be useful for the restoration of maspin production in breast cancer.

Impaired binding of insulin to erythrocyte membrane receptor and the activation of nitric oxide synthase by the hormone in human breast cancer

PURPOSE

Nitric oxide, a messenger molecule has been reported as having various antineoplastic properties. The activation of insulin-activated nitric oxide synthase (IANOS) was found to be related to the production of NO as a result of the binding of insulin to its receptor through the activation of tyrosine kinase in erythrocyte membrane. As nitric oxide is reported to be a systemic anticancer agent, studies were carried out to determine the role of insulin receptor binding that lead to the activation of tyrosine kinase and IANOS in erythrocytes in breast cancer.

METHODS

Blood samples were collected from female breast cancer patients who, at the time of participation in the study, had not undergone any therapeutic intervention but had opted for surgery. The binding of insulin to its receptor in erythrocyte membrane and the activation of both receptor tyrosine kinase and IANOS due to the hormone binding were determined and compared with the appropriate control.

RESULTS

It was found that the impaired NO synthesis in erythrocyte membrane in breast cancer was related to the marked decrease of insulin binding sites of the high-affinity hormone receptor population. This impaired insulin binding to high-affinity receptors resulted in the impairment of both reaction velocity (Vmax) of the IANOS and receptor tyrosine kinase activation.

CONCLUSION

These results indicated that the impairment of interaction between insulin and its high-affinity receptors in erythrocyte membrane might be a critical pathophysiological event in the development of breast cancer.