Cancer treatments are rapidly changing.Curative treatment for oesophageal adenocarcinoma currently involves surgery and cytotoxic chemotherapy or chemoradiotherapy.Outcomes for both regimes are generally poor as a res...Cancer treatments are rapidly changing.Curative treatment for oesophageal adenocarcinoma currently involves surgery and cytotoxic chemotherapy or chemoradiotherapy.Outcomes for both regimes are generally poor as a result of tumor recurrence.We have reviewed the key signalling pathways associated with oesophageal adenocarcinomas and discussed the recent trials of novel agents that attempt to target these pathways.There are many trials underway with the aim of improving survival in oesophageal cancer.Currently,phase 2 and 3 trials are focused on MAP kinase inhibition,either through inhibition of growth factor receptors or signal transducer proteins.In order to avoid tumor resistance,it appears to be clear that targeted therapy will be needed to combat the multiple signalling pathways that are in operation in oesophageal adenocarcinomas.This may be achievable in the future with the advent of gene signatures and a combinatorial approach.展开更多
Objective: To knock out the entire Luxs gene of Streptococcus mutans(S.mutans) UA159 strain via homologous recombination and construct a Luxs-deleted mutant strain of S. mutans. To study the difference between the aci...Objective: To knock out the entire Luxs gene of Streptococcus mutans(S.mutans) UA159 strain via homologous recombination and construct a Luxs-deleted mutant strain of S. mutans. To study the difference between the acid resistance of S. mutans Ingbritt C international standard strain and the acid resistance of LuxS mutant strain. Methods: Two DNA fragments locating in the upper and downstream of Luxs gene were amplified and a erythromycin resistance gene of PJT10 between them were engineered into PUC19 plasmid for constructing the recombination plasmid pUCluxKO. Electrotransformation of S.mutans cells with pUCluxKO-mutant resulted in isolation of erythromycin resistant S. mutans transformants, which was identified by polymerase chain reaction, V.harveyi BB170 luminescence bioassay and sequencing analysis. Solutions of S. mutans standard strain and LuxS mutant strain with same density were made and cultured at pH 3.5 to 7.0 BHI liquid for the same period.Terminal growth situation was compared.Firstly acidized in pH 5.5 BHI liquid,the two strains were cultured at pH 3.0 BHI liquid. The acid tolerance responses of the two strains were compared.Results:Restriction endonuclease analyses showed that pUCluxKO-mutant vector had been successfully recombined. The Luxs-deleted status of S.mutans mutants was confirmed by PCR with primers which were specific for the genes of Luxs and Erythromycin resistance. S.mutans mutant can not induce bioluminescence, indiating the mutant had been successfully recombined. After twenty generations of culture, the constructed Chinese S.mutans mutants were confirmed to be stable. Significant difference of aciduricity was observed between S.mutans standard strain and LuxS mutant strain.The acid resistance of standard strain was stronger than that of LuxS mutant strain.The two strains both displayed the capability of acid tolerance responses. Conclusion:The S.mutans gene allelic exchange plasmid is constructed correctively and a Luxs-negative mutants of S.mutans is constructed, which can help to further study the role of Luxs in the pathogenesis of S.mutans. LuxS mutant strain is more sensitive to acid inactivation,but the capability of acid tolerance responses exist still.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
OBJECTIVE: To examine whether a combinative treatment with curcumin enhances the effects of the epidermal growth factor receptor-tyrosine kinase inhibitor(EGFR-TKI) gefitinib on cell proliferation, clonogenic capacity...OBJECTIVE: To examine whether a combinative treatment with curcumin enhances the effects of the epidermal growth factor receptor-tyrosine kinase inhibitor(EGFR-TKI) gefitinib on cell proliferation, clonogenic capacity and apoptosis in the drug-resistant lung cancer cell line NCI-H1975, and further investigate the molecular mechanisms involved.METHODS: NCI-H1975 cells were treated with curcumin and gefitinib alone or in combination, and cell proliferation, clonogenic capacity and apoptosis were examined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay, clone forming experiments, and flow cytometry, respectively, while p38, extracellular regulated protein kinase(ERK)1/2, and protein kinase B(AKT)phosphorylation were examined using Western blotting.RESULTS: Compared with the effects of either agent alone, the combination of curcumin and gefitinib had a stronger suppressive effect on proliferation and the clonogenic capacity(P < 0.05), and showed an increased ability to promote apoptosis(P < 0.05) and reduce p38, ERK1/2, and AKT phosphorylation(P < 0.05).CONCLUSION: Co-treatment of curcumin and gefitinib significantly improves the ability of gefitinib to inhibit cell proliferation, suppress the clonogenic capacity and enhance apoptosis in NCI-H1975 cells,and these effects are possibly mediated via a decrease in phosphorylation of proteins in downstream pathways of the epidermal growth factor receptor.展开更多
基金Supported by UK National Institute of Health Research/Cancer Research Network (UK NIHR/UKCRN) and Research and Development Department of Wrightington Wigan and Leigh NHS Foundation Trust (to Ang YS)R Keld WrightingtonWigan and Leigh NHS Foundation Trust Cancer Therapy Fund(to Keld RR,in part)
文摘Cancer treatments are rapidly changing.Curative treatment for oesophageal adenocarcinoma currently involves surgery and cytotoxic chemotherapy or chemoradiotherapy.Outcomes for both regimes are generally poor as a result of tumor recurrence.We have reviewed the key signalling pathways associated with oesophageal adenocarcinomas and discussed the recent trials of novel agents that attempt to target these pathways.There are many trials underway with the aim of improving survival in oesophageal cancer.Currently,phase 2 and 3 trials are focused on MAP kinase inhibition,either through inhibition of growth factor receptors or signal transducer proteins.In order to avoid tumor resistance,it appears to be clear that targeted therapy will be needed to combat the multiple signalling pathways that are in operation in oesophageal adenocarcinomas.This may be achievable in the future with the advent of gene signatures and a combinatorial approach.
文摘Objective: To knock out the entire Luxs gene of Streptococcus mutans(S.mutans) UA159 strain via homologous recombination and construct a Luxs-deleted mutant strain of S. mutans. To study the difference between the acid resistance of S. mutans Ingbritt C international standard strain and the acid resistance of LuxS mutant strain. Methods: Two DNA fragments locating in the upper and downstream of Luxs gene were amplified and a erythromycin resistance gene of PJT10 between them were engineered into PUC19 plasmid for constructing the recombination plasmid pUCluxKO. Electrotransformation of S.mutans cells with pUCluxKO-mutant resulted in isolation of erythromycin resistant S. mutans transformants, which was identified by polymerase chain reaction, V.harveyi BB170 luminescence bioassay and sequencing analysis. Solutions of S. mutans standard strain and LuxS mutant strain with same density were made and cultured at pH 3.5 to 7.0 BHI liquid for the same period.Terminal growth situation was compared.Firstly acidized in pH 5.5 BHI liquid,the two strains were cultured at pH 3.0 BHI liquid. The acid tolerance responses of the two strains were compared.Results:Restriction endonuclease analyses showed that pUCluxKO-mutant vector had been successfully recombined. The Luxs-deleted status of S.mutans mutants was confirmed by PCR with primers which were specific for the genes of Luxs and Erythromycin resistance. S.mutans mutant can not induce bioluminescence, indiating the mutant had been successfully recombined. After twenty generations of culture, the constructed Chinese S.mutans mutants were confirmed to be stable. Significant difference of aciduricity was observed between S.mutans standard strain and LuxS mutant strain.The acid resistance of standard strain was stronger than that of LuxS mutant strain.The two strains both displayed the capability of acid tolerance responses. Conclusion:The S.mutans gene allelic exchange plasmid is constructed correctively and a Luxs-negative mutants of S.mutans is constructed, which can help to further study the role of Luxs in the pathogenesis of S.mutans. LuxS mutant strain is more sensitive to acid inactivation,but the capability of acid tolerance responses exist still.
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 Natural Science Found of Zhejiang Province:Research of Molecular Mechanism of Curcumin Reversing TKI Targeted Drug Resistance of NSCLC(No.LY13H160037)
文摘OBJECTIVE: To examine whether a combinative treatment with curcumin enhances the effects of the epidermal growth factor receptor-tyrosine kinase inhibitor(EGFR-TKI) gefitinib on cell proliferation, clonogenic capacity and apoptosis in the drug-resistant lung cancer cell line NCI-H1975, and further investigate the molecular mechanisms involved.METHODS: NCI-H1975 cells were treated with curcumin and gefitinib alone or in combination, and cell proliferation, clonogenic capacity and apoptosis were examined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay, clone forming experiments, and flow cytometry, respectively, while p38, extracellular regulated protein kinase(ERK)1/2, and protein kinase B(AKT)phosphorylation were examined using Western blotting.RESULTS: Compared with the effects of either agent alone, the combination of curcumin and gefitinib had a stronger suppressive effect on proliferation and the clonogenic capacity(P < 0.05), and showed an increased ability to promote apoptosis(P < 0.05) and reduce p38, ERK1/2, and AKT phosphorylation(P < 0.05).CONCLUSION: Co-treatment of curcumin and gefitinib significantly improves the ability of gefitinib to inhibit cell proliferation, suppress the clonogenic capacity and enhance apoptosis in NCI-H1975 cells,and these effects are possibly mediated via a decrease in phosphorylation of proteins in downstream pathways of the epidermal growth factor receptor.
