A hammerhead ribozyme which site-specifically cleaved the GUC position in canon 880 of the mdr1 mRNA was designed. The target site was chosen between the two ATP binding sites, which may be important for the function ...A hammerhead ribozyme which site-specifically cleaved the GUC position in canon 880 of the mdr1 mRNA was designed. The target site was chosen between the two ATP binding sites, which may be important for the function of the P-Gp as an ATP-dependent pump. A DNA sequence encoding the ribozyme gene was then incorporated into a eukaryotic expression vector (pH Apr-1 neo) and transfected into the breast cancer cell line MCF-7/Adr, which is resistant to adriamycin and expresses the MDR phenotype. The ribozyme was stably expressed in the cell line by the RNA dot blotting assay. The result of Northern blot assay showed that the expressed ribozyme could decrease the level of mdrl mRNA expression by 83. 5 %; and the expressed ribozyme could inhibite the formation of p-glycoprotein detected by immuno- cy-tochemistry assay and could reduce the cell’s resistance to adrimycin; this means that the resistant cells were 1 000-fold more resistant than the parental cell line(MCF-7), whereas those cell clones that showed ribozyme expression were only 6-fold more resistant than the parental cell line. These results show that a potentially useful tool is at hand which may inactivate MDR1 mRNA and revert the multidrug resistance phenotype.展开更多
The ability of two dihydrostilbene derivatives erianin and chrysotoxine from Dendrobium chrysotoxum to reverse multidrug resistant (MDR) cells was investigated using murine B16 melanoma cells transfected with the huma...The ability of two dihydrostilbene derivatives erianin and chrysotoxine from Dendrobium chrysotoxum to reverse multidrug resistant (MDR) cells was investigated using murine B16 melanoma cells transfected with the human MDR 1 gene and crossresistant to vinblastine and adriamycin (B16/h MDR 1 cells). Both of the two compounds were shown to increase the accumulation of adriamycin, the P glycoprotein (P gp) substrate, in B16/h MDR 1 transfectants.展开更多
Cancer is still one of the important diseases that threatens the health of people. Multidrug resistance(MDR) is the main factor that leads to the failure of cancer chemotherapy. Thus, MDR diagnosis could facilitate th...Cancer is still one of the important diseases that threatens the health of people. Multidrug resistance(MDR) is the main factor that leads to the failure of cancer chemotherapy. Thus, MDR diagnosis could facilitate the monitoring of the therapy process and realization of efficient treatment of tumors. In this study, we have tried to use a new tetrathiafulvalene(TTF) derivative(TTF-(COONBu4)2) to sensitively recognize the MDR through the multi-signal responsive strategy. The relevant electrochemical and spectroscopic studies demonstrate the specific binding behavior of TTF-(COONBu4)2 with P-glycoprotein(P-gp) as well as drug-resistant leukemia cells. Especially due to the over-expression of specific components of P-gp on the plasma membranes of drug resistant cells, the electrochemical and hydrophilic/hydrophobic features of drug resistant-leukemia cells are apparently different from those of other kinds of leukemia cells. Meanwhile, Fourier transform infrared spectroscopic study illustrates that the most intense vibration band of TTF moieties in the 1400–1600 cm-1 range is almost smeared out upon binding to P-gp, and the binding of TTF-(COONBu4)2 to P-gp may also lead to changes in protein secondary structure and backbone. This observation may advance the development of the new TTF agent for the promising clinical diagnosis and monitoring of MDR of tumors with the aim of successful chemotherapy for human cancer.展开更多
Overexpression of P-glycoprotein （P-gp） encoded by the multidrug resistance gene-1 （MDR-1） is the main mechanism responsible for multidrug resistance （MDR） in a majority of cancer cells. However, the mechanism b...Overexpression of P-glycoprotein （P-gp） encoded by the multidrug resistance gene-1 （MDR-1） is the main mechanism responsible for multidrug resistance （MDR） in a majority of cancer cells. However, the mechanism by which cancer cells acquire high levels of P-gp has not been well defined. Accumulating evidence suggests that nuclear receptors （NRs）, especially human pregnane X receptor （PXR）, play a crucial role in multidrug resistance. It has been shown that chemotherapeutic drug activates PXR and then enhances P-gp expression. Genetic knockdown or pharmacologic inhibition of PXR led to attenuation of drug-induced MDR1 over expression, implying that NRs may be an effective target to reverse multidrug resistance. Recent investigations suggested that transcriptional activity of NRs is mediated by methylases, the important enzymes involved in epigenetic regulation. Other epigenetic modifications, such as promoter methylation, histone deacetylases and microRNAs, were also found to be involved in activation of MDR1 promoter, though the underlying mechanisms are not thoroughly known. In this review, we summarized recent researches in the regulation of P-gp expression, with particular focus on NRs and epigenetics, aiming to provide references and options to reverse and/or prevent MDR in cancer treatment.展开更多
Chemotherapy-induced multi-drug resistance(MDR) in tumors poses a huge challenge for clinical treatment of tumors. The downregulation of the multi-drug resistance relative protein, represented by P-glycoprotein(P-gp),...Chemotherapy-induced multi-drug resistance(MDR) in tumors poses a huge challenge for clinical treatment of tumors. The downregulation of the multi-drug resistance relative protein, represented by P-glycoprotein(P-gp), can reverse MDR of cancer cells. In this study, we developed doxorubicin-loading nanocarrier based on the assembly of protein and antisense oligonucleotide(ASO) to combat MDR of cancer cells. The data demonstrate that the nanocarrier can efficiently deliver ASO to cytoplasm and downregulate the P-glycoprotein expression, subsequently improving the therapeutic effects of Dox in doxorubicin-resistant MCF-7/ADR cancer cells. The preparation is simple and effective, providing a powerful tool for gene delivery. Therefore, our nanocarrier shows high promise in cancer treatment.展开更多
基金This research was supported by the National Natural ScienceYouth Grant.
文摘A hammerhead ribozyme which site-specifically cleaved the GUC position in canon 880 of the mdr1 mRNA was designed. The target site was chosen between the two ATP binding sites, which may be important for the function of the P-Gp as an ATP-dependent pump. A DNA sequence encoding the ribozyme gene was then incorporated into a eukaryotic expression vector (pH Apr-1 neo) and transfected into the breast cancer cell line MCF-7/Adr, which is resistant to adriamycin and expresses the MDR phenotype. The ribozyme was stably expressed in the cell line by the RNA dot blotting assay. The result of Northern blot assay showed that the expressed ribozyme could decrease the level of mdrl mRNA expression by 83. 5 %; and the expressed ribozyme could inhibite the formation of p-glycoprotein detected by immuno- cy-tochemistry assay and could reduce the cell’s resistance to adrimycin; this means that the resistant cells were 1 000-fold more resistant than the parental cell line(MCF-7), whereas those cell clones that showed ribozyme expression were only 6-fold more resistant than the parental cell line. These results show that a potentially useful tool is at hand which may inactivate MDR1 mRNA and revert the multidrug resistance phenotype.
文摘The ability of two dihydrostilbene derivatives erianin and chrysotoxine from Dendrobium chrysotoxum to reverse multidrug resistant (MDR) cells was investigated using murine B16 melanoma cells transfected with the human MDR 1 gene and crossresistant to vinblastine and adriamycin (B16/h MDR 1 cells). Both of the two compounds were shown to increase the accumulation of adriamycin, the P glycoprotein (P gp) substrate, in B16/h MDR 1 transfectants.
基金supported by the National Natural Science Foundation of China(81325011)the National High Technology Research&Development Program of China(2012AA022703)+1 种基金the National Basic Research Program of China(2010CB732404)the Major Science&Technology Project of Suzhou(ZXY2012028)
文摘Cancer is still one of the important diseases that threatens the health of people. Multidrug resistance(MDR) is the main factor that leads to the failure of cancer chemotherapy. Thus, MDR diagnosis could facilitate the monitoring of the therapy process and realization of efficient treatment of tumors. In this study, we have tried to use a new tetrathiafulvalene(TTF) derivative(TTF-(COONBu4)2) to sensitively recognize the MDR through the multi-signal responsive strategy. The relevant electrochemical and spectroscopic studies demonstrate the specific binding behavior of TTF-(COONBu4)2 with P-glycoprotein(P-gp) as well as drug-resistant leukemia cells. Especially due to the over-expression of specific components of P-gp on the plasma membranes of drug resistant cells, the electrochemical and hydrophilic/hydrophobic features of drug resistant-leukemia cells are apparently different from those of other kinds of leukemia cells. Meanwhile, Fourier transform infrared spectroscopic study illustrates that the most intense vibration band of TTF moieties in the 1400–1600 cm-1 range is almost smeared out upon binding to P-gp, and the binding of TTF-(COONBu4)2 to P-gp may also lead to changes in protein secondary structure and backbone. This observation may advance the development of the new TTF agent for the promising clinical diagnosis and monitoring of MDR of tumors with the aim of successful chemotherapy for human cancer.
文摘Overexpression of P-glycoprotein （P-gp） encoded by the multidrug resistance gene-1 （MDR-1） is the main mechanism responsible for multidrug resistance （MDR） in a majority of cancer cells. However, the mechanism by which cancer cells acquire high levels of P-gp has not been well defined. Accumulating evidence suggests that nuclear receptors （NRs）, especially human pregnane X receptor （PXR）, play a crucial role in multidrug resistance. It has been shown that chemotherapeutic drug activates PXR and then enhances P-gp expression. Genetic knockdown or pharmacologic inhibition of PXR led to attenuation of drug-induced MDR1 over expression, implying that NRs may be an effective target to reverse multidrug resistance. Recent investigations suggested that transcriptional activity of NRs is mediated by methylases, the important enzymes involved in epigenetic regulation. Other epigenetic modifications, such as promoter methylation, histone deacetylases and microRNAs, were also found to be involved in activation of MDR1 promoter, though the underlying mechanisms are not thoroughly known. In this review, we summarized recent researches in the regulation of P-gp expression, with particular focus on NRs and epigenetics, aiming to provide references and options to reverse and/or prevent MDR in cancer treatment.
基金supported by the National Natural Science Foundation of China (21325520, 21327009, 21405041, J1210040)the Foundation for Innovative Research Groups of National Natural Science Foundation of China (21521063)the Science and Technology Project of Hunan Province (2016RS2009, 2016WK2002)
文摘Chemotherapy-induced multi-drug resistance(MDR) in tumors poses a huge challenge for clinical treatment of tumors. The downregulation of the multi-drug resistance relative protein, represented by P-glycoprotein(P-gp), can reverse MDR of cancer cells. In this study, we developed doxorubicin-loading nanocarrier based on the assembly of protein and antisense oligonucleotide(ASO) to combat MDR of cancer cells. The data demonstrate that the nanocarrier can efficiently deliver ASO to cytoplasm and downregulate the P-glycoprotein expression, subsequently improving the therapeutic effects of Dox in doxorubicin-resistant MCF-7/ADR cancer cells. The preparation is simple and effective, providing a powerful tool for gene delivery. Therefore, our nanocarrier shows high promise in cancer treatment.
