Sulindac enhances the killing of cancer cells exposed to oxidative stress.

BACKGROUND: Sulindac is an FDA-approved non-steroidal anti-inflammatory drug (NSAID) that affects prostaglandin production by inhibiting cyclooxygenases (COX) 1 and 2. Sulindac has also been of interest for more than decade as a chemopreventive for adenomatous colorectal polyps and colon cancer. PRINCIPAL FINDINGS: Pretreatment of human colon and lung cancer cells with sulindac enhances killing by an oxidizing agent such as tert-butyl hydroperoxide (TBHP) or hydrogen peroxide. This effect does not involve cyclooxygenase (COX) inhibition. However, under the conditions used, there is a significant increase in reactive oxygen species (ROS) within the cancer cells and a loss of mitochondrial membrane potential, suggesting that cell death is due to apoptosis, which was confirmed by Tunel assay. In contrast, this enhanced killing was not observed with normal lung or colon cells. SIGNIFICANCE: These results indicate that normal and cancer cells handle oxidative stress in different ways and sulindac can enhance this difference. The combination of sulindac and an oxidizing agent could have therapeutic value.

Topical sulindac combined with hydrogen peroxide in the treatment of actinic keratoses.

BACKGROUND: Actinic keratoses (AKs) are a precancerous condition of the skin that have the potential to become squamous cell cancer (SCC). Sulindac is a Food and Drug Administration (FDA)-approved nonsteroidal anti-inflammatory drug (NSAID) that has been shown to have clinically significant anticancer effects. Malignant cells may have a different response to oxidative stress than normal cells. OBJECTIVE: To establish a role of increased reactive oxygen species (ROS) in the mechanism of cancer killing by sulindac in the presence of an oxidizing agent. To assess the tolerability and efficacy of the combination of gels containing sulindac and hydrogen peroxide in the treatment of patients with AKs. METHODS: Cell culture studies were performed using a skin SCC cell line and normal human epidermal keratinocytes. After treatment with sulindac and an oxidizing agent, cell viability, and intracellular ROS levels were measured. An open-label clinical trial was performed using sulindac and hydrogen peroxide gels daily for 3 weeks on AKs involving the upper extremities. RESULTS: In SCC cells, a combination of sulindac and an oxidizing agent lead to 400 to 500% increases in intracellular ROS, which resulted in significant cell death. In sharp contrast, normal keratinocytes did not show increases in ROS levels and were not killed. A clinical trial using the combination of sulindac and hydrogen peroxide therapy in 5 patients with AKs revealed that 60% of the treated AKs responded and 50% showed no residual AK on histopathology specimens after skin biopsy. LIMITATIONS: The small number of patients and the lack of a placebo group. CONCLUSION: Increased levels of ROS appear to be important in the selective killing of cancer cells in the presence of sulindac and oxidizing agents. Further studies are necessary to define the role of the combination of sulindac and oxidizing agent therapy in patients with AKs and skin cancer.

Methionine sulfoxide reductases: history and cellular role in protecting against oxidative damage.

An enzyme that can reduce methionine sulfoxide in proteins was first discovered in Escherichia coli about 25 years ago. It is now apparent that there is a family of enzymes, referred to as methionine sulfoxide reductases (Msr), and in recent years there has been considerable interest in one of the members of the Msr family, MsrA. This enzyme has been shown to protect cells against oxidative damage, which suggests a possible role in a large number of age-related diseases. This review summarizes the history of the discovery of MsrA, properties of the enzyme and its role in protecting cells against oxidative damage. Other members of the Msr family that differ in substrate specificity and localization are described as well as a possible role for the Msr system in drug metabolism. The concept that the Msr system can be used to develop novel drugs that could be catalytic anti-oxidants is discussed.

Reduction of Sulindac to its active metabolite, sulindac sulfide: assay and role of the methionine sulfoxide reductase system.

Sulindac is a known anti-inflammatory drug that functions by inhibition of cyclooxygenases 1 and 2 (COX). There has been recent interest in Sulindac and other non-steroidal anti-inflammatory drugs (NSAID) because of their anti-tumor activity against colorectal cancer. Studies with sulindac have indicated that it may also function as an anti-tumor agent by stimulating apoptosis. Sulindac is a pro-drug, containing a methyl sulfoxide group, that must be reduced to sulindac sulfide to be active as a COX inhibitor. In the present studies we have developed a simple assay to measure sulindac reduction and tested sulindac as a substrate for 6 known members of the methionine sulfoxide reductase (Msr) family that have been identified in Escherichia coli. Only MsrA and a membrane associated Msr can reduce sulindac to the active sulfide. The reduction of sulindac also has been demonstrated in extracts of calf liver, kidney, and brain. Sulindac reductase activity is also present in mitochondria and microsomes.