Upregulation of Hsp72 mediates anoxia/reoxygenation neuroprotection in the freshwater turtle via modulation of ROS.

The neuroprotective role of Hsp72 has been demonstrated in several ischemic/stroke models to occur primarily through mediation of apoptotic pathways, and a number of heat shock proteins are upregulated in animal models capable of extended anoxic survival. In the present study, we investigated the role of Hsp72 on cell death and apoptotic regulators in one anoxia tolerant model system, the freshwater turtle Trachemys scripta. Since Hsp72 is known to regulate apoptosis through interactions with Bcl-2, we manipulated the levels of Hsp72 and Bcl-2 with siRNA in neuronally enriched primary cell cultures and examined downstream effects.

Combination of sulindac and dichloroacetate kills cancer cells via oxidative damage.

Sulindac is an FDA-approved non-steroidal anti-inflammatory drug with documented anticancer activities. Our recent studies showed that sulindac selectively enhanced the killing of cancer cells exposed to oxidizing agents via production of reactive oxygen species (ROS) resulting in mitochondrial dysfunction. This effect of sulindac and oxidative stress on cancer cells could be related to the defect in respiration in cancer cells, first described by Warburg 50 years ago, known as the Warburg effect.

Studies on the metabolism and biological activity of the epimers of sulindac.

Sulindac is a nonsteroidal, anti-inflammatory drug (NSAID) that has also been studied for its anticancer activity. Recent studies suggest that sulindac and its metabolites act by sensitizing cancer cells to oxidizing agents and drugs that affect mitochondrial function, resulting in the production of reactive oxygen species and death by apoptosis. In contrast, normal cells are not killed under these conditions and, in some instances, are protected against oxidative stress.

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.

Modulation of stress proteins and apoptotic regulators in the anoxia tolerant turtle brain.

Freshwater turtles survive prolonged anoxia and reoxygenation without overt brain damage by well-described physiological processes, but little work has been done to investigate the molecular changes associated with anoxic survival. We examined stress proteins and apoptotic regulators in the turtle during early (1 h) and long-term anoxia (4, 24 h) and reoxygenation. Western blot analyses showed changes within the first hour of anoxia; multiple stress proteins (Hsp72, Grp94, Hsp60, Hsp27, and HO-1) increased while apoptotic regulators (Bcl-2 and Bax) decreased.

Preliminary evidence of neuronal regeneration in the anoxia tolerant vertebrate brain.

Postnatal neurogenesis in response to stroke or ischemia is currently of great medical interest. In this study, we investigated the potential for neurogenesis in an anoxia tolerant vertebrate in response to global ischemia. The results suggest sustained neurogenesis in the turtle that increases after ischemic damage, thus revealing a potential physiological adaptation to repeated anoxia-reoxygenation events.

Suppression of reactive oxygen species production enhances neuronal survival in vitro and in vivo in the anoxia-tolerant turtle Trachemys scripta.

Hypoxia-ischemia with reperfusion is known to cause reactive oxygen species-related damage in mammalian systems, yet, the anoxia tolerant freshwater turtle is able to survive repeated bouts of anoxia/reoxygenation without apparent damage. Although the physiology of anoxia tolerance has been much studied, the adaptations that permit survival of reoxygenation stress have been largely ignored. In this study, we examine ROS production in the turtle striatum and in primary neuronal cultures, and examine the effects of adenosine (AD) on cell survival and ROS.