ABSTRACT
Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a human oncoprotein that is overexpressed in various tumors. A previous study found that CIP2A expression is associated with doxorubicin (Dox) resistance. In the present study, we investigated whether cucurbitacin B (CuB), a natural anticancer compound found in Cucurbitaceae, reversed multidrug resistance (MDR) and downregulated CIP2A expression in MCF-7/Adriamycin (MCF-7/Adr) cells, a human breast multidrug-resistant cancer cell line. CuB treatment significantly suppressed MCF-7/Adr cell proliferation, and reversed Dox resistance. CuB treatment also induced caspase-dependent apoptosis, decreased phosphorylation of Akt (pAkt). The suppression of pAkt was mediated through CuB-induced activation of protein phosphatase 2A (PP2A). Furthermore, CuB activated PP2A through the suppression of CIP2A. Silencing CIP2A enhanced CuB-induced growth inhibition, apoptosis and MDR inhibition in MCF-7/Adr cells. In conclusion, we found that enhancement of PP2A activity by inhibition of CIP2A promotes the reversal of MDR induced by CuB.
Subject(s)
Autoantigens/metabolism , Doxorubicin/pharmacology , Drug Resistance, Multiple/drug effects , Membrane Proteins/metabolism , Protein Phosphatase 2/metabolism , Triterpenes/pharmacology , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Breast Neoplasms/drug therapy , Breast Neoplasms/metabolism , Caspases/metabolism , Cell Line, Tumor , Cell Proliferation/drug effects , Cucurbitaceae/chemistry , Down-Regulation/drug effects , Female , Gene Expression Regulation, Neoplastic/drug effects , Humans , Intracellular Signaling Peptides and Proteins , MCF-7 Cells , Phosphorylation/drug effects , Proto-Oncogene Proteins c-akt/metabolismABSTRACT
Oridonin (Ori), a diterpenoid compound extracted from traditional medicinal herbs, elicits antitumor effects on many cancer types. However, whether Ori can be used in gefitinib-resistant non-small cell lung cancer (NSCLC) cells remains unclear. This study investigated the antitumor activity and underlying mechanisms of Ori. Results demonstrated that this compound dose-dependently inhibited the proliferation, invasion, and migration of the gefitinib-resistant NSCLC cells in vitro. Ori also significantly downregulated the phosphorylation of EGFR, ERK, Akt, expression levels of matrix metalloproteinase-12 (MMP-12), and the cancerous inhibitor of protein phosphatase 2A (CIP2A). In addition, Ori upregulated protein phosphatase 2A (PP2A) activity of gefitinib-resistant NSCLC cells. Ori combined with docetaxel synergistically inhibited these cells. Ori also inhibited tumor growth in murine models. Immunohistochemistry results further revealed that Ori downregulated phospho-EGFR, MMP-12, and CIP2A in vivo. These findings indicated that Ori can inhibit the proliferation, invasion, and migration of gefitinib-resistant NSCLC cells by suppressing EGFR/ERK/MMP-12 and CIP2A/PP2A/Akt signaling pathways. Thus, Ori may be a novel effective candidate to treat gefitinib-resistant NSCLC.
Subject(s)
Carcinoma, Non-Small-Cell Lung/drug therapy , Diterpenes, Kaurane/administration & dosage , Drug Resistance, Neoplasm/drug effects , Lung Neoplasms/drug therapy , Quinazolines/administration & dosage , A549 Cells , Animals , Autoantigens/metabolism , Carcinoma, Non-Small-Cell Lung/metabolism , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Survival/drug effects , Diterpenes, Kaurane/pharmacology , Dose-Response Relationship, Drug , ErbB Receptors/metabolism , Gefitinib , Gene Expression Regulation, Neoplastic/drug effects , Humans , Intracellular Signaling Peptides and Proteins , Lung Neoplasms/metabolism , MAP Kinase Signaling System/drug effects , Matrix Metalloproteinase 12/metabolism , Membrane Proteins/metabolism , Mice , Phosphorylation/drug effects , Quinazolines/pharmacology , Xenograft Model Antitumor AssaysABSTRACT
The paper proposed novel designs to pinch the transverse diffusion of the sample in the injection mode using microelectrodes to generate the potential difference at the channel intersection in the capillary electrophoresis (CE) microchip. A pair of microelectrodes was used to conduct the injection channel and the separation channel, which directly provided the potential to pinch the sample without using a power supply. These new designs of the CE microchip simplify the electric circuitry and improve performance. Simulations were performed using the CFD-ACE[trade mark sign] software. The mechanisms of diffusion and electrophoresis were employed in the numerical simulation. The injection and separation processes of the sample were simulated and the parameters of the present design were investigated numerically.
Subject(s)
Electrochemistry/instrumentation , Electrophoresis, Capillary/instrumentation , Computer Simulation , Equipment Design , Microelectrodes , MicrofluidicsABSTRACT
Au nanoparticles modified with 21-base thiolated-oligonucleotides have been evaluated as delivery vehicles for the development of a nonviral transfection platform. The electromigration combined with electroporation for DNA delivery in an osteoblast like cell was employed to test on microchips. Electroporation introduces foreign materials into cells by applying impulses of electric field to induce multiple transient pores on the cell membrane through dielectric breakdown of the cell membrane. On the basis of the characteristic surface plasmon of the Au particles, UV-vis absorption was utilized to qualitatively judge the efficiency of delivery. Transmission electron microscopy images and atomic absorption measurements (quantitative analysis) provided evidence of the bare Au and Au/oligonucleotide nanoparticles before and after electroporation and electromigration function. The experiments demonstrated that electrophoretic migration followed by electroporation significantly enhanced the transportation efficiency of the nanoparticle-oligonucleotide complexes as compared with electroporation alone. Most interestingly, Au capped with oligonucleotides led to optimal performance. On the other hand, the bare Au colloidal suspensions resulted in aggregation, which might be an obstacle to the internalization process. In addition, analytical results demonstrated an increase in the local particle concentrations on the cell surface that provided additional support for the mechanism underlying the improved Au nanoparticle transportation into cells in the presence of electromigration function.
