ABSTRACT
The aurora kinases constitute one family of serine/threonine kinases whose activity is essential for mitotic progression. The aurora kinases are frequently upregulated in human cancers and are associated with sensitivity to chemotherapy in certain ones. In the present study, we investigated whether aurora kinases could be a target to overcome radioresistance or enhance the radiosensitivity of lung cancer. For that purpose, we determined the therapeutic potential of daurinol, an investigational topoisomerase inhibitor, alone and in combination with radiation, by observing its effect on aurora kinases. Daurinol decreased cell viability and proliferation in human colon and lung cancer cells. Gene expression in daurinol-treated human colon cancer cells was evaluated using RNA microarray. The mRNA expression of 18 genes involved in the mitotic spindle check point, including aurora kinase A (AURKA) and aurora kinase B (AURKB), was decreased in daurinol-treated human colon cancer cells as compared with vehicle-treated cells. As expected, radiation increased expression levels of AURKA and AURKB. This increase was effectively attenuated by siRNAs against AURKA and AURKB, which suppressed cell growth and increased apoptosis under radiation. Furthermore, the expression of AURKA and AURKB was suppressed by daurinol in the presence or absence of radiation in colon and lung cancer cells. Daurinol alone or in combination with radiation decreased lung cancer growth in xenograft mouse models. Our data clearly confirm the antitumor and radiosensitizing activity of daurinol in human lung cancer cells through the inhibition of AURKA and AURKB.
Subject(s)
Aurora Kinase A/genetics , Aurora Kinase B/genetics , Benzodioxoles/pharmacology , Gene Expression Regulation, Enzymologic/drug effects , Gene Expression Regulation, Neoplastic/drug effects , Lung Neoplasms/drug therapy , Naphthalenes/pharmacology , Animals , Apoptosis/drug effects , Apoptosis/radiation effects , Aurora Kinase A/metabolism , Aurora Kinase B/metabolism , Blotting, Western , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Proliferation/radiation effects , Cell Survival/drug effects , Cell Survival/radiation effects , Centrosome/drug effects , Centrosome/radiation effects , Chemoradiotherapy , Female , Gene Expression Regulation, Enzymologic/radiation effects , Gene Expression Regulation, Neoplastic/radiation effects , Genomic Instability/drug effects , Genomic Instability/genetics , Genomic Instability/radiation effects , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , HCT116 Cells , Humans , Lung Neoplasms/pathology , Lung Neoplasms/radiotherapy , Mice, Inbred NOD , Mice, SCID , Microscopy, Fluorescence , RNA Interference , Reverse Transcriptase Polymerase Chain Reaction , Xenograft Model Antitumor Assays/methodsABSTRACT
BACKGROUND: Previous studies have reported that elevated total homocysteine levels are associated with cognitive dysfunction. However, few studies have examined the radiological markers of associated neuropathology in Alzheimer's disease (AD). We hypothesized that elevated levels of homocysteine are associated with cerebral grey matter volume loss. We compared the grey matter in a high homocysteine group and a normal homocysteine group using an optimized voxel-based morphometry. METHODS: The study included 79 patients with AD who were divided into two groups: a high homocysteine group and a normal homocysteine group. The participants underwent brain magnetic resonance imaging using a standardized protocol and neurocognitive evaluation. Homocysteine tests and other routine laboratory examinations for dementia assessment were carried out in all patients. RESULTS: There was no significant difference in grey matter volume between the patients with high homocysteine levels and those with normal homocysteine levels. A multiple regression analysis also revealed that the levels of homocysteine were not associated with the grey matter volume in patients with AD. Homocysteine levels were not correlated significantly with Mini-Mental State Examination, Global Deterioration Scale, or Clinical Dementia Rating. CONCLUSION: Our results showed that elevated homocysteine levels are not associated with reduced cerebral grey matter volume in AD. Larger samples will be needed to assess potential correlations between homocysteine and neuroanatomical pathology in the future.
ABSTRACT
Anthracycline anticancer agents are widely used in the cancer chemotherapy for hepatocelluar carcinoma. However, accurate kinetic analyses of the hepatocellular uptake and efflux of the drugs have not been reported. We, therefore, investigated the hepatobiliary transport of epirubicin, an anthracycline derived antibiotic, after intravenous (i.v.) infusion in rats. The hepatic uptake mechanisms of epirubicin were also investigated in isolated rat hepatocytes. To analyze epirubicin levels in the biological samples, we used an HPLC-based method which has been validated for a kinetic study by suitable criteria. The uptake process of epirubicin by the hepatocytes revealed one saturable component, with a Km of 99.1 µg/mL and Vmax of 3.70 µg/min/10(6) cells. The initial uptake velocity of epirubicin was significantly inhibited in a temperature-dependent manner. The velocity was also reduced in the presence of metabolic inhibitors such as rotenone or carbonylcyanide-p-(trifluoromethoxy)-phenylhydrazone. Substrates for organic anion transporters such as bromosulfophthalein and taurocholate significantly inhibited the initial uptake velocity of epirubicin. We also attempted to determine the hepatobiliary transport of epirubicin after i.v. infusion in vivo. At steady-state after i.v. infusion of epirubicin (10-160 µg/min/kg), the drug was extensively accumulated in the liver, followed by excretion into bile. Furthermore, the CLbile,plasma and CLbile,liver decreased with a corresponding increase in the Css,plasma and Css,liver. In conclusion, present studies using isolated rat hepatocytes and in vivo i.v. infusion demonstrate that epirubicin is likely to be taken up into liver cells via organic anion transporting polypeptides, and that its biliary excretion might be mediated via specific transporters.
