| Human’health and life are threatened greatly by cancer. The death number due to tumor occupies the first place among the various types of diseases each year. Drug-resistance in tumor cells is one of boring problems in chemotherapy. In general, drug-resistance is correlated to drug efflux transporters (P-glycoprotein, multidrug resistance protein, lung resistance protein, etc.), apoptosis-regnlating genes (p53, Caspase3, Bcl-2, Bax, ect.) and relevant enzymes (cytochrome P450, glutathine S-transferase, DNA Topoisomerase Ⅱ, etc.). Therefore, the investigations on the drug-resistance mechanisms and descovery of some drugs reversing drug-resistance are valid solutions for overcoming the failure of cancer chemotherapy. In this paper, the reversal effect of active small molecules in traditional Chinese medicine on drug-resistance and the expression of integrin β1on cell membrane were investigated using electrochemical method and piezoelectric sensing technique. The main contents are summarized as follows:1. The dynamic attachment and growth process of adriamycin-resistant human breast cancer MCF-7cells (MCF-7/ADR) in the presence of adriamycin (ADR) and ginsenoside Rh2(G-Rh2) using quartz crystal microbalance (QCM). The experimental results indicate that G-Rh2could inhibit the proliferation of MCF-7/ADR in a concentration-dependent way. The combined treatment of G-Rh2with ADR at non-effect dosage resulted in the higher inhibition efficiencies and the increased cell-death velocity, suggesting excellent ability of G-Rh2for reversal of multidrug resistance in MCF-7/ADR cells. The cytotoxic effect of the ADR-G-Rh2combination was evaluated with the modified Burgi formula (Jin equation) based on the QCM responses. It presented apparent synergism, indicating the potential ability of G-Rh2in tumor therapy. Fluorescent microscopic inspection and methyl thiazolyl tetrazolium (MTT) assay were also carried out and exhibited the comparable results to QCM analysis. The present work may lay an experimental foundation for the application of ginsenosides in cancer therapy, especial in multidrug resistance research.2. Integrin α5β1was adsorbed on the gold-nanoparticle modified glassy carbon electrode to bind integrin (31monoclonal antibody (anti-CD29mAb). A sandwich structure was then formed using nanocomposites consisted of horseradish peroxidase (HRP) labeled antiantibody and gold nanoparticles. HRP bound on the electrode surface could cause an amperometric response of the hydroquinone-H2O2system. The assembly of the sandwich structure was inhibited by tumor cells to give decreased enzyme-catalytic signals due to the capture of anti-CD29mAb by integrin (31on cell membranes. Under optimal conditions the relative current change (S) was proportional to the cell concentration from1.6×103to2.0×106cells mL-1with a detection limit of700cells ml/1. Integrin β1 expression in MCF-7/ADR cells was found to be significantly higher than that in MCF-7cells, indicating the increased adhesion ability of MCF-7/ADR cells.3. The revelant chemical reactions in the process of cell dissociation were studied using electrochemical method and piezoelectric sensing technique. It can be found that the interaction between trypsin and fibronectin (FN) resulted in the structure change of the latter. Integrin α5β1suffered hydrolysis and desorption from electrode surface in the presence of trypsin. A replacement reaction existed between integrin α5β1-FN complex and trypsin. Trypsin could destroy integrin α5β1-FN complex and react with FN in place of integrin α5β1, leading to desorption and hydrolysis of the cell adhesive molecules. |
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