Chemotherapy resistance plays a pivotal role in the prognosis and therapeutic failure of patients with colorectal cancer(CRC).Cisplatin(DDP)-resistant cells exhibit an inherent ability to evade the toxic chemotherapeu...Chemotherapy resistance plays a pivotal role in the prognosis and therapeutic failure of patients with colorectal cancer(CRC).Cisplatin(DDP)-resistant cells exhibit an inherent ability to evade the toxic chemotherapeutic drug effects which are characterized by the activation of slow-cycle programs and DNA repair.Among the elements that lead to DDP resistance,O^(6)-methylguanine(O^(6)-MG)-DNA-methyltransferase(MGMT),a DNA-repair enzyme,performs a quintessential role.In this study,we clarify the significant involvement of MGMT in conferring DDP resistance in CRC,elucidating the underlying mechanism of the regulatory actions of MGMT.A notable upregulation of MGMT in DDP-resistant cancer cells was found in our study,and MGMT repression amplifies the sensitivity of these cells to DDP treatment in vitro and in vivo.Conversely,in cancer cells,MGMT overexpression abolishes their sensitivity to DDP treatment.Mechanistically,the interaction between MGMT and cyclin dependent kinase 1(CDK1)inducing slow-cycling cells is attainted via the promotion of ubiquitination degradation of CDK1.Meanwhile,to achieve nonhomologous end joining,MGMT interacts with XRCC6 to resist chemotherapy drugs.Our transcriptome data from samples of 88 patients with CRC suggest that MGMT expression is co-related with the Wnt signaling pathway activation,and several Wnt inhibitors can repress drug-resistant cells.In summary,our results point out that MGMT is a potential therapeutic target and predictive marker of chemoresistance in CRC.展开更多
Recent studies revealed the relationship among homologous recombination repair(HRR),androgen receptor(AR),and poly(adenosine diphosphate-ribose)polymerase(PARP);however,the synergy between anti-androgen enzalutamide(E...Recent studies revealed the relationship among homologous recombination repair(HRR),androgen receptor(AR),and poly(adenosine diphosphate-ribose)polymerase(PARP);however,the synergy between anti-androgen enzalutamide(ENZ)and PARP inhibitor olaparib(OLA)remains unclear.Here,we showed that the synergistic effect of ENZ and OLA significantly reduced proliferation and induced apoptosis in AR-positive prostate cancer cell lines.Next-generation sequencing followed by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed the significant effects of ENZ plus OLA on nonhomologous end joining(NHEJ)and apoptosis pathways.ENZ combined with OLA synergistically inhibited the NHEJ pathway by repressing DNA-dependent protein kinase catalytic subunit(DNA-PKcs)and X-ray repair cross complementing 4(XRCC4).Moreover,our data showed that ENZ could enhance the response of prostate cancer cells to the combination therapy by reversing the anti-apoptotic effect of OLA through the downregulation of anti-apoptotic gene insulin-like growth factor 1 receptor(IGF1R)and the upregulation of pro-apoptotic gene death-associated protein kinase 1(DAPK1).Collectively,our results suggested that ENZ combined with OLA can promote prostate cancer cell apoptosis by multiple pathways other than inducing HRR defects,providing evidence for the combined use of ENZ and OLA in prostate cancer regardless of HRR gene mutation status.展开更多
Human polymorphonuclear leukocytes (PMN) have been reported to completely lack of DNA-dependent protein kinase (DNA-PK) which is composed of Ku protein and the catalytic subunit DNA-PKcs, needed for nonhomologous end-...Human polymorphonuclear leukocytes (PMN) have been reported to completely lack of DNA-dependent protein kinase (DNA-PK) which is composed of Ku protein and the catalytic subunit DNA-PKcs, needed for nonhomologous end-joining (NHEJ) of DNA double-strand breaks. Promyelocytic HL-60 cells express a variant form of Ku resulting in enhanced radiation sensitivity. This raises the question if low efficiency of NHEJ, instrumental for the cellular repair of oxidative damage, is a normal characteristic of myeloid differentiation. Here we confirmed the complete lack of DNAPK in P MN protein extracts, and the expression of the truncated Ku86 variant form in HL-60. However, this degradation of DNA-PK was shown to be due to a DNA-PK-degrading protease in PMN and HL-60. In addition, by using a protease-resistant whole cell assay, both Ku86 and DNA-PKcs could be demonstrated in PMN, suggesting the previously reported absence in PMN of DNA-PK to be an artefact. The levels of Ku86 and DNA-PKcs were much reduced in PMN, as compared with that of the lymphocytes, whereas HL-60 displayed a markedly elevated DNA-PK concentration.In conclusion, our findings provide evidence of reduced, not depleted expression of DNA-PK during the mature stages of myeloid differentiation.展开更多
To improve the performance of yeast cell factories for industrial production,extensive CRISPR-mediated genome editing systems have been applied by artificially creating double-strand breaks(DSBs)to introduce mutations...To improve the performance of yeast cell factories for industrial production,extensive CRISPR-mediated genome editing systems have been applied by artificially creating double-strand breaks(DSBs)to introduce mutations with the assistance of intracellular DSB repair.Diverse strategies of DSB repair are required to meet various demands,including precise editing or random editing with customized gRNAs or a gRNA library.Although most yeasts remodeling techniques have shown rewarding performance in laboratory verification,industrial yeast strain manipulation relies only on very limited strategies.Here,we comprehensively reviewed the molecular mechanisms underlying recent industrial applications to provide new insights into DSB cleavage and repair pathways in both Saccharomyces cerevisiae and other unconventional yeast species.The discussion of DSB repair covers the most frequently used homologous recombination(HR)and nonhomologous end joining(NHEJ)strategies to the less well-studied illegitimate recombination(IR)pathways,such as single-strand annealing(SSA)and microhomology-mediated end joining(MMEJ).Various CRISPR-based genome editing tools and corresponding gene editing efficiencies are described.Finally,we summarize recently developed CRISPR-based strategies that use optimized DSB repair for genome-scale editing,providing a direction for further development of yeast genome editing.展开更多
基金supported by grants from the National Natural Science Foundation of China(Grant Nos.:82003807,82173394)the Shaanxi Province Science Foundation,China(Grant No.:2023-GHZD-19)+1 种基金the Medical Foundation-Clinical Integration Program of Xi'an Jiaotong University,China(Grant No.:YXJLRH2022043)the Xi'an Jiaotong University Free Exploration and Innovation-Teacher Project Foundation,China(Grant No.:xzy012023104).
文摘Chemotherapy resistance plays a pivotal role in the prognosis and therapeutic failure of patients with colorectal cancer(CRC).Cisplatin(DDP)-resistant cells exhibit an inherent ability to evade the toxic chemotherapeutic drug effects which are characterized by the activation of slow-cycle programs and DNA repair.Among the elements that lead to DDP resistance,O^(6)-methylguanine(O^(6)-MG)-DNA-methyltransferase(MGMT),a DNA-repair enzyme,performs a quintessential role.In this study,we clarify the significant involvement of MGMT in conferring DDP resistance in CRC,elucidating the underlying mechanism of the regulatory actions of MGMT.A notable upregulation of MGMT in DDP-resistant cancer cells was found in our study,and MGMT repression amplifies the sensitivity of these cells to DDP treatment in vitro and in vivo.Conversely,in cancer cells,MGMT overexpression abolishes their sensitivity to DDP treatment.Mechanistically,the interaction between MGMT and cyclin dependent kinase 1(CDK1)inducing slow-cycling cells is attainted via the promotion of ubiquitination degradation of CDK1.Meanwhile,to achieve nonhomologous end joining,MGMT interacts with XRCC6 to resist chemotherapy drugs.Our transcriptome data from samples of 88 patients with CRC suggest that MGMT expression is co-related with the Wnt signaling pathway activation,and several Wnt inhibitors can repress drug-resistant cells.In summary,our results point out that MGMT is a potential therapeutic target and predictive marker of chemoresistance in CRC.
基金This work was supported by the National Natural Science Foundation of China(82002718)the Jiangsu Natural Science Foundation(BK20191077)Jiangsu Province Hospital(the First Affiliated Hospital of Nanjing Medical University)Clinical Capacity Enhancement Project(JSPH-MC-2021-12).
文摘Recent studies revealed the relationship among homologous recombination repair(HRR),androgen receptor(AR),and poly(adenosine diphosphate-ribose)polymerase(PARP);however,the synergy between anti-androgen enzalutamide(ENZ)and PARP inhibitor olaparib(OLA)remains unclear.Here,we showed that the synergistic effect of ENZ and OLA significantly reduced proliferation and induced apoptosis in AR-positive prostate cancer cell lines.Next-generation sequencing followed by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed the significant effects of ENZ plus OLA on nonhomologous end joining(NHEJ)and apoptosis pathways.ENZ combined with OLA synergistically inhibited the NHEJ pathway by repressing DNA-dependent protein kinase catalytic subunit(DNA-PKcs)and X-ray repair cross complementing 4(XRCC4).Moreover,our data showed that ENZ could enhance the response of prostate cancer cells to the combination therapy by reversing the anti-apoptotic effect of OLA through the downregulation of anti-apoptotic gene insulin-like growth factor 1 receptor(IGF1R)and the upregulation of pro-apoptotic gene death-associated protein kinase 1(DAPK1).Collectively,our results suggested that ENZ combined with OLA can promote prostate cancer cell apoptosis by multiple pathways other than inducing HRR defects,providing evidence for the combined use of ENZ and OLA in prostate cancer regardless of HRR gene mutation status.
文摘Human polymorphonuclear leukocytes (PMN) have been reported to completely lack of DNA-dependent protein kinase (DNA-PK) which is composed of Ku protein and the catalytic subunit DNA-PKcs, needed for nonhomologous end-joining (NHEJ) of DNA double-strand breaks. Promyelocytic HL-60 cells express a variant form of Ku resulting in enhanced radiation sensitivity. This raises the question if low efficiency of NHEJ, instrumental for the cellular repair of oxidative damage, is a normal characteristic of myeloid differentiation. Here we confirmed the complete lack of DNAPK in P MN protein extracts, and the expression of the truncated Ku86 variant form in HL-60. However, this degradation of DNA-PK was shown to be due to a DNA-PK-degrading protease in PMN and HL-60. In addition, by using a protease-resistant whole cell assay, both Ku86 and DNA-PKcs could be demonstrated in PMN, suggesting the previously reported absence in PMN of DNA-PK to be an artefact. The levels of Ku86 and DNA-PKcs were much reduced in PMN, as compared with that of the lymphocytes, whereas HL-60 displayed a markedly elevated DNA-PK concentration.In conclusion, our findings provide evidence of reduced, not depleted expression of DNA-PK during the mature stages of myeloid differentiation.
基金supported by the National Key Research and Development Program of China(No.2021YFC2101203)the General project of National Natural Science Foundation of China(No.22078021).
文摘To improve the performance of yeast cell factories for industrial production,extensive CRISPR-mediated genome editing systems have been applied by artificially creating double-strand breaks(DSBs)to introduce mutations with the assistance of intracellular DSB repair.Diverse strategies of DSB repair are required to meet various demands,including precise editing or random editing with customized gRNAs or a gRNA library.Although most yeasts remodeling techniques have shown rewarding performance in laboratory verification,industrial yeast strain manipulation relies only on very limited strategies.Here,we comprehensively reviewed the molecular mechanisms underlying recent industrial applications to provide new insights into DSB cleavage and repair pathways in both Saccharomyces cerevisiae and other unconventional yeast species.The discussion of DSB repair covers the most frequently used homologous recombination(HR)and nonhomologous end joining(NHEJ)strategies to the less well-studied illegitimate recombination(IR)pathways,such as single-strand annealing(SSA)and microhomology-mediated end joining(MMEJ).Various CRISPR-based genome editing tools and corresponding gene editing efficiencies are described.Finally,we summarize recently developed CRISPR-based strategies that use optimized DSB repair for genome-scale editing,providing a direction for further development of yeast genome editing.
