Harris Baker posted an update 1 year ago
Other mitochondrion-related cellular alterations that are important in modulating apoptotic include induction of ROS. We observed that CSC vapor-selected acquisition of resistance to cisplatin was marked by the presence of decreased mitochondrial membrane potential and increased basal levels of ROS. Comparable levels of ROS generation and DYm depolarization might have resulted in cellular apoptosis and cell death in unexposed cells. However, we also observed that chronic CSC exposed cells are resistant to DYm depolarization-induced apoptosis. Similar findings were also reported in an oral keratinocytes. AK3 is a mitochondrial-matrix protein which is downregulated by chronic CSC exposure. We observed decreased DYm and increase in ROS production in AK3 overexpressed, cisplatin treated cells. Studies have indicated activation of NF-kB, histone modification and chromatin remodeling in response to CSC. Studies by the same group also indicate an increase in NF-kB in response to ROS. Mitochondrial death signaling via multi domain Bcl-2 family members Bax and Bak can be interrupted by Bcl-xL, an antiapoptotic member of the Bcl-2 family, which sequesters and counteracts the proaopototic signals. Our results indicate an increase in the expression of Bcl-xL in the CSC vapor exposed cells compared to the parental cells. Bcl-xL has been found to be up-regulated in breast cancer cells lines and primary breast tumors and is considered a marker for increased tumor grade and nodal metastaisis. Cells expressing Bcl-xL are more likely to survive following DNA damage and can potentially accumulate new somatic mutations at higher frequencies. An increase in the Bcl-xL/ Bax ratio provides DNA damage induced resistance and survival to many cancer cell types. Even though we observe an increase in the basal levels of mitochondrial depolarization and ROS generation in response to CSC vapor, these signals may be counteracted by increase in the Bcl-xL/ Bax ratio, which may increase the cellular survival of the cells due to selective pressure of the surrounding environment which PD325901 enable them to escape apoptosis and acquire resistance to chemotherapeutic drugs. Our current study does not rule out other mechanisms of resistance to cisplatin, such as decreased uptake, inactivation by nucleophilic compounds, or accelerated DNA repair, in CSCexposed urothelial cells. In addition, the precise mechanism of how AK3 sensitizes cells to cisplatin has not yet been clearly defined. Of relevance to the studies herein, the linkage of translational suppression of AK3 that mediate CSC vapor-induced toxicity and cisplatin resistance that has not been previously reported. However, new data links Pre-miR-181a and pre-miR-630 with modulation of both mitochondrial and post mitochondrial steps of the intrinsic pathway of apoptosis, including mitochondrial transmembrane potential dissipation, in cisplatin resistant lung cancer cells. Studies are ongoing in our laboratory to understand these and other cellular pathways involved in the regulation of AK3 in response to CSC vapor and cisplatin. Alcoholic liver disease is the hepatic manifestation of chronic alcohol injury, a major cause of liver failure worldwide, and the second leading indication for liver transplantation in the United States. Avoidance of alcohol can ameliorate disease, but few patients are able to achieve abstinence. Therefore, understanding the pathogenic mechanisms of ALD is critical to addressing this public health problem. Studies have associated insulin resistance with disease severity of ALD in humans and in rodent models ; and therapies aimed at improving insulin sensitivity improve experimental ALD. We have demonstrated that the onset of insulin resistance is temporally related to the development of hepatic steatosis, an early histologic feature of ALD, thus linking hepatic steatosis with the pathogenesis of ALD. Hepatic steatosis results from several perturbations of lipid metabolism including direct and indirect cellular injury and impairment of key lipid homeostatic pathways. The histologic focal point of hepatic steatosis is the intrahepatic lipid droplet, a dynamic organelle now recognized to have critical functions in cellular lipid homeostasis. Lipid droplets are comprised of cores of mostly neutral lipids surrounded by a phospholipid monolayer of lipids, metabolically active enzymes, and lipid droplet proteins. The Perilipin family of lipid droplet proteins associates with the phospholipid monolayer and we and others have shown that these proteins have roles in both lipid and glucose homeostasis in cell culture and animal models of non-alcoholic fatty liver disease. The role lipid droplet biology plays in the pathogenesis of ALD, however, is not well understood. In the liver, Perilipin 2 is the most abundant lipid droplet protein; while Perilipin 3 is mildly expressed and Perilipin 1 is de novo expressed in non-alcoholic steatohepatitis. Plin2 is found in steroidogenic and metabolically active cells ; reduces the turnover of triglyceride ; and regulates fatty acid metabolic enzymes. Furthermore, we and others have shown that Plin2 deficiency protects against diet-induced obesity and insulin resistance. The specific role of Plin2 in ALD is not known. In ALD rodent models, Plin2 is increased in the livers of mice and rats chronically fed alcohol. We recently reported that the increase in hepatic Plin2 is twice that of mice fed a control-liquid diet and the upregulation of Plin2 temporally coincides with the onset of hepatic steatosis, glucose intolerance and increase in hepatic ceramides.