Chitosan/Ellagic Acid Composite Materials for Local Cancer Therapy

Current advances in the drug delivery have improved the therapeutic efficacy of the drug and minimized risks of side effects associated with toxicity of the drug. Implantable polymeric delivery system has gained increasing attentions for controlled drug release and localized treatments. In comparison to conventional chemotherapy, polymeric delivery systems are implantable at a local targeted site and biodegradable after a sufficient therapeutic span. The objectives of this project were to fabricate and characterize an implantable polymeric vehicle for a local chemotherapy and investigate its biological properties against cancer cells including human WM115 melanoma, human U87 glioblastoma, and rat C6 glioma cells in vitro andin vivo. In this study, a natural chitosan polymer was employed as a drug vehicle and ellagic acid (EA), a naturally occurring phenolic compound, was incorporated as a therapeutic agent. The chitosan/ellagic acid composite films were developed by combining 1% (w/v) chitosan solution with different concentrations (0.05, 0.1, 0.5, 1, or 20% (w/v)) of ellagic acid for a local chemotherapy. Characterization of composite films was performed on chemical structure, crystallinity, surface morphology, degradation behavior, and release profile. Cancer cell activity on the composite films was evaluated through direct and indirect cell culture using MTS assay. Anti-cancer mechanism of the composite films against cancer cells was investigated using apoptosis assay, caspase-3 activation, western blot for p53, and anti-angiogenesis assays. In the in vivo study, an animal subcutaneous model was used to assess the anti-tumor effect of the composite film on rat C6 glioma. Treatments were initiated by implanting the composite films onto the tumor. The tumor growth was monitored by measuring tumor volume using a caliper, an ultrasound machine, and an optical imaging system. The chitosan/ellagic acid composite films exhibited increase in amide and ester linkages, diffraction peaks of the crystallized ellagic acid, enhanced surface roughness, and hydrophilicity with increasing concentration of ellagic acid. The composite films degraded enzymatically, indicated by at least a 5 times higher concentration of free amino groups in the incubation medium at 3 weeks compared with 1 day. They also displayed a sustained slow release of ellagic acid in vitro for 3 weeks incubation. Anti-cancer activity of the composite films was ellagic acid concentration dependent by inducing apoptosis of cancer cells and suppressing angiogenesis. Significant inhibitory effect (p\u3c0.05) was found in the composite films containing 0.5% (w/v) of ellagic acid or higher compared with other groups. Study of a rat C6 glioma model demonstrated that the composite film (Ch/EA20) significantly inhibited tumor growth compared with control groups in vivo. Tumor volume increase in Ch/EA20 group was 9 times lower than that in control groups at 3 weeks observation by measuring a caliper. No severe weight loss (\u3e10% wt.) was observed from all groups. Histology observation indicated no evidence of severe toxicity surrounding the composite films. The high efficacy and low toxicity of the composite film was attributed to the slow release and localized effect of ellagic acid. In order to further improve the delivery method and efficacy, chitosan based injectable hydrogel was developed for a local administration of ellagic acid to avoid surgical complications. Studies of the chitosan gel were performed with regard to chemical structure, surface morphology, viscoelasticity, release profile, and degradation behavior. Biocompatibility and anti-cancer activity on chitosan gel delivery system were examined. The results showed that the injectable chitosan liquid formulation underwent thermal gelation at body temperature via hydrophobic interactions using β-glycerophosphate salt (β-GP). Sol-gel transition was dependent on final pH values of the chitosan/β-GP solution and temperature. Dialysis of chitosan solution reduced the β-GP needed to reach pH 7.2, resulting in 4 times higher cell viability than undialyzed chitosan gel at 3 days culture. This result indicates improved biocompatibility of the delivery system. The chitosan/β-GP gels were enzymatically degradable for 3 weeks incubation and inhibited cancer cell growth in vitro in an ellagic acid concentration dependent manner. The significant inhibitory effect (p\u3c0.05) was found in the gel containing 1% (w/v) of ellagic acid compared with other groups. Viability of U87 cells and C6 cells cultured on chitosan gels containing 1% (w/v) of ellagic acid were lower than the same cells on chitosan gels at 3 days incubation by 3.8 times and 6.5 times, respectively. This research has demonstrated that the chitosan/ellagic acid delivery system is a promising biomaterial for a local cancer treatment. This study has also suggested a potential strategy with higher efficacy and lower toxicity to treat tumors by the combination of naturally based biopolymers such as chitosan and phenolic compounds such as ellagic acid. This study provides some rationale for further investigation of implantable polymeric delivery system

Combining Noxa-Inducing Drugs with ABT-263 to Efficiently Increase Cell Death in Head and Neck Squamous Cell Carcinoma (HNSCC)

Head and neck cancer is the sixth leading cancer worldwide. Head and neck squamous cell carcinoma (HNSCC) accounts for more than 90% of incident cases. Despite intense, multimodality treatment regimens for HNSCC including surgery, chemotherapy, and radiation, little progress has been made over the past 30 years in improving overall survival rates. Tumor cell death induced by both conventional and targeted chemotherapy is often mediated by the BCL-2 family-dependent mitochondrial apoptotic pathway. However, initiators of this apoptotic pathway, such as p53, are more than 50% of the time mutated or deleted in HNSCC rendering the disease refractory to treatment. To counter such resistance, direct therapeutic targeting of the BCL-2 family is conceptually appealing. For this purpose, we use three clinically-available drugs: cisplatin, fenretinide, and ABT-263 (navitoclax). Both cisplatin and fenretinide are known to induce a BH3-only pro-apoptotic protein, Noxa, which binds to and inactivates multi-domain anti-apoptotic protein MCL-1 and release from its interaction with multi-domain pro-apoptotic protein BAK, followed by the phosphorylation via CDK2 for the proteasome-mediated degradation. Activated BAK can now go through conformational change for the oligomerization at the outer membrane of the mitochondria to release cytochrome c into the cytosol and induce caspase-dependent apoptotic cell death. ABT-263 directly binds to multi-domain anti-apoptotic proteins, such as BCL-2 and BCL-XL, to inhibit their activity and leads to the activation of multi-domain pro-apoptotic protein BAX to induce apoptosis. We hypothesize that combining the Noxa-inducing drugs (cisplatin or fenretinide) along with ABT-263 can efficiently induce BAX and BAK activation and significantly increase cell death in HNSCC cells by simultaneously inhibiting the activity of MCL-1, BCL-2, and BCL-XL. Combination-induced treatments in four cell lines (HN8, HN30, HN31, and UMSCC1) tested led to significant increase in apoptotic cell death. Cisplatin and ABT-263 combined treatment is inducing the expression of Noxa and leading to increase in apoptosis in HN30, HN31, UMSCC1, but not HN8. Similarly, fenretinide and ABT-263 combined treatment is inducing the expression of Noxa in all four cell lines tested and is largely relying on expression of Noxa

The effect of a market factor on information flow between stocks using minimal spanning tree

We empirically investigated the effects of market factors on the information flow created from N(N-1)/2 linkage relationships among stocks. We also examined the possibility of employing the minimal spanning tree (MST) method, which is capable of reducing the number of links to N-1. We determined that market factors carry important information value regarding information flow among stocks. Moreover, the information flow among stocks evidenced time-varying properties according to the changes in market status. In particular, we noted that the information flow increased dramatically during periods of market crises. Finally, we confirmed, via the MST method, that the information flow among stocks could be assessed effectively with the reduced linkage relationships among all links between stocks from the perspective of the overall market

A novel regulator of the p53-mediated mitochondrial apoptotic pathway

The p53 tumor suppressor protein induces apoptosis in response to genotoxic and environmental stress. Recent studies have revealed the existence of a transcription-independent mitochondrial p53 apoptosis pathway, however the mechanism regulating p53 translocation to mitochondria and subsequent initiation of apoptosis was not known. Here, we show that Tid1, also known as mtHsp40 or Dnaja3, interacts with p53 and directs its translocation to mitochondria in cells exposed to hypoxia. Overexpression of Tid1 in tumor cells promoted mitochondrial localization of both wildtype and mutant forms of p53 and was able to restore the pro-apoptotic activity of mutant p53 proteins that were otherwise unable to induce apoptosis. Tid1's mitochondrial signal sequence and DnaJ domain were both required for the movement of the p53-Tid1 complex from the cytosol to the mitochondria. Our findings establish Tid1 as a novel regulator of p53 localization and apoptotic function

Corporate social responsibility, business groups and financial performance: a study of listed Indian firms

This study explores the relationship between corporate social responsibility (C.S.R.) and financial performance of Indian firms. We also examine the relationship between C.S.R. and financial performance in context of Indian business group firms, which are known to have unique characteristics which differ from those of Indian stand-alone firms. Using a sample of Indian listed firms between 2010 and 2015, we find that C.S.R., as measured by E.S.G. disclosure score, has a U-shaped relationship with Tobin’s Q, supporting the slack resource theory at lower level of CSR and supporting the stakeholder theory at higher level of C.S.R. The empirical results imply that an improvement in CSR actions does not always result in higher firm value but should exceed a certain level of C.S.R. to have a positive effect on firm value. In addition, we find that at lower level, a negative relationship between C.S.R. and Tobin’s Q weakens in group affiliate firms. However, this complement effect of business group disappears at higher level, weakening the positive relationship between C.S.R. and Tobin’s Q. This study offers new insights for the different influence of business groups on C.S.R. performanc

Survivorship in International Chain Restaurant in Korea

Several western chains have done well in Korea, while others have withdrawn from the market. The authors summarize the current operational results of western chain restaurants in Korea, report positive impacts of western foodservice firms, and analyze the key elements leading to their survival and non-survival. Some lessons could be used as tools to establish entrance strategies of western chain restaurants in Korea as well as in other Asian market