Objective To predict clinical chemotherapy sensitivity of primary non-small cell lung cancer（NSCLC） by methylthiazal （MTT） tumor chemosensitivity assay method in vitro and detection of multidrug resistance gene1 （MDR1）, and provide reference for clinical individualized treatment. Methods We selected 80 fresh primary NSCLC samples from NSCLC patients who underwent surgical resection in Zibo Central Hospital Affiliated to Binzhou Medical College between January 2009 and December 2011. There were 46 male patients and 34 female patients with their median age of 54 （29 to 81）years. Viable NSCLC cells obtained from malignant tissue were tested for their sensitivity to cisplatin （DDP）, gemcitabine （GEM）, docetaxe （DOC）, etoposide （VP-16） ,and vinorelbine （NVB） using MTT assay in vitro. Fluorescent quantitative reverse transcriptase-polymerase chain reaction （RT-PCR） was used to analysis the expression level of multidrug resistance gene1 （MDR1）. Results After exposure to antitumor drugs, morphologic changes, decrease of metabolic activity, and apoptosis were detected in NSCLC cells. MTT results showed that different individual cancer cells had different chemosensitivity to antitumor drugs, and cancer cells also had different chemosensitivity to different antitumor drugs. Inhibitory rates of cancer cells exposed to DOC, GEM, and VP-16 were significantly higher than those of cancer cells exposed to DDP and NVB （42.5%±9.5%, 40.5%±6.5%, 38.4%±7.6% versus 31.5%±8.5%，32.5%±7.8%, P＜0.05）.The positive rate of MDR1 in tumor tissues was 40.0% （32/80）. The expression of MDR1 was not associated with tumor histological type, degree of differentiation, lymph node metastasis and TNM stage. The expression of MDR1 was associated with resistance to NVB （χ2=5.209，P=0.022），GEM （χ2=4.769，P=0.029），VP-16 （χ2=4.596，P=0.032），and DDP（χ2=6.086，P=0.014）, but not associated with resistance to DOC（χ2=0.430，P=0.512）. Conclusion MTT chemosensitivity assay can effectively predict clinical chemotherapy sensitivity. Detection of MDR1, together with MTT chemosensitivity assay, can more accurately predict NSCLC chemosensitivity and be a guide for individualized chemotherapy of NSCLC.
Mitochondrial adenosine triphosphate (ATP) synthase is the key enzyme of mitochondrial oxidative phosphorylation reaction.The down-regulation of the mitochondrial ATP synthase is a hallmark of most human carcinomas, which is the embodiment of the bioenergetic signature of cancer in the performance of the decreased oxidative phosphorylation and increased aerobic glycolysis. Combining with the bioenergetic signature of cancer, studies showed that mitochondrial ATP synthase and multidrug resistance and adverse prognosis of tumor were closely related. Its mechanisms are related to post-transcriptional regulation of the ATP synthase,the hypermethylation of the ATP synthase gene and the inhibitor peptide of the mitochondrial ATP synthase, called ATP synthase inhibitory factor 1(IF1). In this review, we stress the biological characteristics of mitochondrial ATP synthase and the relationship between ATP synthase and multidrug resistance and prognosis of Malignant tumor, in order to find a new way for tumor therapy.
Multidrug resistance (MDR) remains the major obstacle to the success of clinical cancer chemotherapy. P-glycoprotein (P-gp), encoded by the MDR1, is an important part with complex mechanisms associated with the MDR. In order to overcome the MDR of tumors, we in the present experimental design incorporated small interfering RNA (siRNA) targeting MDR1 gene and anticancer drug paclitaxel (PTX) into the solid lipid nanoparticles (SLNs) to achieve the combinational therapeutic effects of genetherapy and chemotherapy. In this study, siRNA-PTX-SLNs were successfully prepared. The cytotoxicity of blank SLNs and siRNA-PTX-SLNs in MCF-7 cells and MCF-7/ADR cells were detected by MTT; and the uptake efficiency of PTX in MCF-7/ADR cells were detected via HPLC method; quantitative real-time PCR and flow cytometry were performed to investigate the silencing effect of siRNA-PTX-SLNs on MDR1 gene in MCF-7/ADR cells. The results showed that PTX loaded SLNs could significantly inhibit the growth of tumor cells, and more importantly, the MDR tumor cells treated with siRNA-PTX-SLNs showed the lowest viability. HPLC study showed that SLNs could enhance the cellular uptake for PTX. Meanwhile, siRNA delivered by SLNs significantly decreased the P-gp expression in MDR tumor cells, thus increased the cellular accumulation of rhodamine123 as a P-gp substrate. In conclusion, the MDR1 gene could be silenced by siRNA-PTX-SLNs, which could promote the growth inhibition efficiency of PTX on tumor cells, leading to synergetic effect on MDR tumor therapy.
This paper aims to study the effects of traditional Chinese medicine Euphorbia esula on multidrug resistant human gastric cancer cells in the cell proliferation, migration, invasion and apoptosis, and to study the apoptosis-inducing pathway. Different dilutions of Euphorbia esula extract were used to process human multidrug resistant gastric cancer SGC7901/ADR cells. Cell proliferation inhibition phenomenon was determined by MTT experiment. Nuclear morphological changes of apoptotic cells and apoptotic indexes were observed and determined by Hochest33528 staining followed with fluorescence microscope observing. Flow cytometry was used to detect cell apoptosis rate. Cell migration and invasion ability were observed and determined by Transwell method. Spectrophotometry was used to detect caspase-3 and caspase-9 enzyme activity. Western blotting was used to detect subcellular distribution of cytochrome c. The results showed that Euphorbia esula extract had obvious inhibition effect on proliferation of gastric cancer multidrug resistant SGC7901/ADR cells, which was time- and concentration-dependent. After processing multidrug resistant gastric cancer SGC7901/ADR cells with Euphorbia esula extract, the apoptotic index and apoptosis rate were significantly increased than those in the control group, which showed a time- and dose-dependent mode; but if a caspase inhibitor was added, apoptosis index was not obviously increased. Transwell method showed that migration and invasion ability of the Euphorbia esula extract-processed SGC7901/ADR cells dropped significantly. Spectrophotometry showed that in Euphorbia esula extract-processed SGC7901/ADR cells, caspase-3 and caspase-9 expression were increased, which had significant differences with the control group. Western blotting test showed that the distribution of cytochrome c decreased in mitochondria, while increased in the cytoplasm (i.e., cytochrome c escaped from mitochondria to the cytoplasm). In conclusion, Euphorbia esula extract could inhibit the proliferation, migration and invasion, and induce apoptosis in human gastric cancer multidrug resistant SGC7901/ADR cells; and cytochrome c, caspase-9 and caspase-3 might be involved in cell apoptosis induced by Euphorbia esula extract, suggesting endogenous or mitochondrial apoptotic pathway.