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1.  Arginine-conjugated albumin microspheres inhibits proliferation and migration in lung cancer cells 
Arginine is one of the essential amino acid involved in numerous biosynthetic pathways that significantly influence tumor growth. It has been demonstrated that arginine is effective to inhibit proliferation of cancer cells when an appropriate dose is applied. Generally, induction of cell death requires high concentration of arginine while low concentration of arginine facilitates cell proliferation. In addition to the apoptosis induced by metabolism of arginine, it has also been reported that in an ideal solution environment, arginine may assemble into arginine clusters to kill cancer cells. Therefore, to make the arginine an effective anticancer agent, arginine/albumin microspheres were designed and synthesized to provide a localized high concentration of arginine on tumor sites. In addition, the arginine/albumin mesospheres (AAMS) are also expected to provide an arginine-rich surface on microspheres, which is similar to the arginine cluster, to effectively inhibit tumor growth. In this study, the AAMS were synthesized through a water/organic solvent emulsion system and the surface properties were characterized. The in vitro effects of AAMS on A549, CRL-2081, MAK9 lung cancer cells (LCC) proliferation, migration, and tumor growth were determined. The expression of oncogenic protein EphA2 and transcription factor slug was also determined. AAMS significantly inhibited the cell proliferation, cell migration and tumor growth in all the three LCC, while same concentration of free arginine promoted the LCC tumor growth and migration. Our studies indicate that the synthesized AAMS has a more effective inhibiting effect on proliferation, migration and tumor growth of LCC than freely released arginine. The expression of EphA2 receptor mRNA was significantly decreased when compared to control cells. In addition the mRNA expression of transcription factor slug was also inhibited by AAMS suggesting that AAMS affects the expression of EphA2 and slug and may regulate LCC proliferation and migration. These data suggests that the AAMS can be an ideal delivery vehicle for therapeutic interventions against LCCs.
PMCID: PMC3696533  PMID: 23841026
Arginine-conjugated albumin; microspheres; inhibition; proliferation; migration; lung cancer
2.  Advances in malignant pleural mesothelioma therapy: targeting EphA2 a novel approach 
Malignant pleural mesothelioma (MPM) is an aggressive neoplasm with a poor prognosis. MPM grows from the mesothelial cells lining the surface of the lung and chest wall called Pleura. Exposure to asbestos is mainly linked to the development of MPM. Approximately 80% of the tumors are pleural in origin, and up to 3000 people are diagnosed with MPM in the United States annually. The incidence of MPM is expected to rise in the coming decades particularly in the developing countries. Although there is an increase in the awareness of danger associated with the use of asbestos, its use is still prevalent in Australia and Asia because of its durability and low cost. This further warns and adds to the mortality and morbidity of patients with MPM globally. The traditional treatment strategies have shown only modest improvement towards the disease. MPM is difficult to treat because of the fact that the time between the exposure to asbestos and the appearance of symptoms is extremely delayed, and also due to tumor involvement with the pleural surface and the adjoining tissues such as the chest wall, pericardium and subdiaphragmatic organs. Despite advances in the diagnostic and treatment approaches the median survival rate for MPM is between 9 to 17 months. The standard care with double agent has shown modest improvement however, multimodality approach using novel targets may have potential to achieve the improvement in the survival rate. In this review we give an update on the conventional treatment modalities and discuss about various molecular targets including receptor EphA2, a novel target gene which may be considered as a biomarker for the diagnosis and treatment of MPM.
PMCID: PMC3304568  PMID: 22432060
Receptor EphA2; EphrinA1; malignant pleural mesothelioma; receptor tyrosine kinases; asbestos; surgery; chemotherapy; gene therapy
3.  Silencing receptor EphA2 induces apoptosis and attenuates tumor growth in malignant mesothelioma 
Receptor EphA2 over-expression is associated with the aggressive nature of growth in malignant mesothelioma (MM) and silencing EphA2 with interference RNA suppressed MM proliferation. The mechanisms associated with targeting the EphA2 gene in MM were not clear. We sought to determine whether silencing EphA2 induces apoptosis in MM cells by either extrinsic or intrinsic pathways. The receptor EphA2 signaling pathway may provide attractive therapeutic strategy for MM. Apoptosis was determined by Cell Death ELISA in MM Cells transfected with siRNA-EphA2 and control siRNA. The gene expression profile of apoptosis pathways were analyzed by GEArray. Selected genes were further studied by quantitative PCR, Western analysis, and immunofluorescence. Caspases activities were measured by fluorescence spectrometer. Silencing EphA2 expression induced apoptosis in MMC. Apoptosis was characterized by FADD expression, activated caspase-8, caspase-3 and induction of Bax, Bak, and Bid as revealed by GEArray and protein fractionation assays. The expression of FADD, Bid, caspase-8, cytochrome-c and apaf-1 were significantly higher in the cytosolic fractions of EphA2-siRNA transfected cells. Furthermore, blocking the expression of caspase-8 by an inhibitor blunted FADD expression, indicating that caspase-8 is implicated in EphA2-siRNA induced apoptosis in MMC. Our data indicates that targeting the EphA2 gene by siRNA induced both extrinsic and intrinsic apoptotic pathways in MM Cells. Receptor EphA2 inhibition may be an effective approach for inhibiting MM growth and a promising direction for MM therapy.
PMCID: PMC3180062  PMID: 21968554
Receptor EphA2; malignant mesothelioma; interference RNA; siRNA; apoptosis; therapy

Results 1-3 (3)