Overexpression of aldose reductase in human cancer tissues.

BACKGROUND: Aldose reductase (AR) belongs to the aldo-keto reductase (AKR) super family and catalyzes the conversion of aldoses to the corresponding alcohol. Some recent studies have shown overexpression of AR and AR-like proteins in human liver cancers and some cancer cell lines such as HepG2 and HeLa cells. However, apart from hepatic cancer tissue, the status of AR expression has not been reported in other human cancer tissues. Therefore, in this preliminary report, the expression of AR in a few other commonly occurring cancer tissues was investigated. MATERIAL/METHODS: Fresh post-surgical tumor tissues of breast, ovary, cervix, and rectum were collected from subjects who were admitted for surgical therapy of tumors. Tumor area and tumor characteristics were determined by histopathological analysis. The expression and activity of AR in tumor and non-tumor areas was carried out by immunohistochemical, immunoblotting, and enzyme activity studies. RESULTS: Immunoblotting results indicated overexpression of AR in breast, ovarian, cervical, and rectal cancerous tissues. Furthermore, biochemical data revealed that the specific activity of AR was higher in tumor areas than in non-tumor regions of these tissues. The overexpression of AR in tumor tissue was further validated by immunohistochemistry in the case of breast tissue. CONCLUSIONS: These preliminary results suggest overexpression and increased activity of AR in different human cancers. However, the incidence of AR overexpression and its role in drug resistance needs to be established with a large number of samples of various cancers.

Curcumin and turmeric delay streptozotocin-induced diabetic cataract in rats.

PURPOSE: The purpose of this study was to investigate the effect of curcumin and its source, turmeric, on streptozotocin-induced diabetic cataract in rats. METHODS: Wistar-NIN rats were selected and diabetes was induced by streptozotocin (35 mg/kg body weight, intraperitoneally) and divided into four groups (group II-V). The control (group I) rats received only vehicle. Group I and II animals received an unsupplemented AIN-93 diet, and those in groups III, IV, and V received 0.002% and 0.01% curcumin and 0.5% turmeric, respectively, in an AIN-93 diet for a period of 8 weeks. Cataract progression due to hyperglycemia was monitored by slit lamp biomicroscope and classified into four stages. At the end of 8 weeks, the animals were killed and the biochemical pathways involved in the pathogenesis of cataract such as oxidative stress, polyol pathway, alterations in protein content and crystallin profile in the lens were investigated, to understand the possible mechanism of action of curcumin and turmeric. Blood glucose and insulin levels were also determined. RESULTS: Although, both curcumin and turmeric did not prevent streptozotocin-induced hyperglycemia, as assessed by blood glucose and insulin levels, slit lamp microscope observations indicated that these supplements delayed the progression and maturation of cataract. The present studies suggest that curcumin and turmeric treatment appear to have countered the hyperglycemia-induced oxidative stress, because there was a reversal of changes with respect to lipid peroxidation, reduced glutathione, protein carbonyl content and activities of antioxidant enzymes in a significant manner. Also, treatment with turmeric or curcumin appears to have minimized osmotic stress, as assessed by polyol pathway enzymes. Most important, aggregation and insolubilization of lens proteins due to hyperglycemia was prevented by turmeric and curcumin. Turmeric was more effective than its corresponding levels of curcumin. CONCLUSIONS: The results indicate that turmeric and curcumin are effective against the development of diabetic cataract in rats. Further, these results imply that ingredients in the study's dietary sources, such as turmeric, may be explored for anticataractogenic agents that prevent or delay the development of cataract.