Deregulation of the cell cycle results in loss of normal control mechanisms that prevent aberrant cell proliferation and cancer progression. Regulation of the cell cycle is a highly complex process with many layers of...Deregulation of the cell cycle results in loss of normal control mechanisms that prevent aberrant cell proliferation and cancer progression. Regulation of the cell cycle is a highly complex process with many layers of control. One of these mechanisms involves timely degradation of CDK inhibitors (CKIs) like p27Kip1 by the ubiquitin proteasomal system (UPS). Cks1 is a 9 kDa protein which is frequently overexpressed in different tumor subtypes, and has pleiotropic roles in cell cycle progression, many of which remain to be fully characterized. One well characterized molecular role of Cks1 is that of an essential adaptor that regulates p27Kip1 abundance by facilitating its interaction with the SCF-Skp2 E3 ligase which appends ubiquitin to p27Kip1 and targets it for degradation through the UPS. In addition, emerging research has uncovered p27Kip1-independent roles of Cks1 which have provided crucial insights into how it may be involved in cancer progression. We review here the structural features of Cks1 and their functional implications, and also some recently identified Cks1 roles and their involvement in breast and other cancers.展开更多
OBJECTIVE To investigate 3-O-(Z)-coumaroyloleanolic acid(3-COA),an active ingredient of oleanolic acid in the TAIWANG leaves of E.oldhamii Maxim,that has been shown to have antitumor activity against A549 lung cancer ...OBJECTIVE To investigate 3-O-(Z)-coumaroyloleanolic acid(3-COA),an active ingredient of oleanolic acid in the TAIWANG leaves of E.oldhamii Maxim,that has been shown to have antitumor activity against A549 lung cancer cells,overcomes Cks1b-induced chemoresistance in lung cancer by inhibiting Hsp90 and MEK pathways.METHODS Cisplatin(CDDP)and doxorubicin(DOX)sensitivity was assessed through proliferation,viability,and clonogenic potential induction in cells overexpressing Cks1b(Cks1b-OE).The mechanism for resistance and 3-COA sensitivity were elucidated by immunoblot analysis of Hsp90 and MEK,and confirmed by sh RNA knockdown.Inhibition of 3-COA or3-COA combined with CDDP(3-COA&CDDP)was assayed in early primary lung cancer(IPH),late primary lung cancer(RFH)cells,and tumor-burdened immunodeficiency mice in vivo.RESULTS The ectopic overexpression of Cks1b in human lung cancer cells induces chemoresistance of the cells to CDDP and DOX,but not3-COA,through mechanisms independent of its canonical Skp2-p27 pathway.Further dissection with application of shR NA and selective inhibitors reveals that Hsp90 and MEK1/2 are the critical components of the non-canonical pathways responsible for the Cks1b-induced chemoresistance.Interestingly,inhibition of either Hsp90 or MEK1/2rendered a similar magnitude of antitumor activity by resensitization of the chemoresistant Cks1b-OE cells to CDDP and DOX,suggesting that both Hsp90 and MEK1/2are essentialto Cks1b for induction of chemoresistance.IC50of 3-COA is 6.82μmol·L-1in H358 Cks1b and8.22μmol·L-1in H226 Cks1b,which were not significantly higher than those in H358 EV and H226 EV,respectively.Furthermore,3-COA mimicked PU-H71,a Hsp90-specific inhibitor,targeted Hsp90 and MEK to reduce the expression of their downstream,respectively.Importantly,compared with CDDP treatment,3-COA or 3-COA&CDDP signifi-cantly inhibited RFH cells in vitro.Moreover,3-COA or3-COA&CDDP significantly prolonged more survival for a H358 Cks1b-OE inducing tumor-burdened mice than PD98059(a MEK-specific inhibitor)in vivo.CONCLUSION Our data report for the first time that Cks1b employs Hsp90 and MEK1/2 pathways in lung cancer cells to develop chemoresistance and identify 3-COA as a potential antitumor drug for clinical treatment of chemoresistant lung cancer.展开更多
文摘Deregulation of the cell cycle results in loss of normal control mechanisms that prevent aberrant cell proliferation and cancer progression. Regulation of the cell cycle is a highly complex process with many layers of control. One of these mechanisms involves timely degradation of CDK inhibitors (CKIs) like p27Kip1 by the ubiquitin proteasomal system (UPS). Cks1 is a 9 kDa protein which is frequently overexpressed in different tumor subtypes, and has pleiotropic roles in cell cycle progression, many of which remain to be fully characterized. One well characterized molecular role of Cks1 is that of an essential adaptor that regulates p27Kip1 abundance by facilitating its interaction with the SCF-Skp2 E3 ligase which appends ubiquitin to p27Kip1 and targets it for degradation through the UPS. In addition, emerging research has uncovered p27Kip1-independent roles of Cks1 which have provided crucial insights into how it may be involved in cancer progression. We review here the structural features of Cks1 and their functional implications, and also some recently identified Cks1 roles and their involvement in breast and other cancers.
基金The project supported by National Natural Science Foundation of China(81402023)Natural Science Foundation of Guangdong Province(2014A030310022)+1 种基金Scientific Research Projects of Guangzhou(201510010212)College Students Cultivate Special Science and Technology Innovation Projects of Guangdong in 2016(pdjh2016b0408)
文摘OBJECTIVE To investigate 3-O-(Z)-coumaroyloleanolic acid(3-COA),an active ingredient of oleanolic acid in the TAIWANG leaves of E.oldhamii Maxim,that has been shown to have antitumor activity against A549 lung cancer cells,overcomes Cks1b-induced chemoresistance in lung cancer by inhibiting Hsp90 and MEK pathways.METHODS Cisplatin(CDDP)and doxorubicin(DOX)sensitivity was assessed through proliferation,viability,and clonogenic potential induction in cells overexpressing Cks1b(Cks1b-OE).The mechanism for resistance and 3-COA sensitivity were elucidated by immunoblot analysis of Hsp90 and MEK,and confirmed by sh RNA knockdown.Inhibition of 3-COA or3-COA combined with CDDP(3-COA&CDDP)was assayed in early primary lung cancer(IPH),late primary lung cancer(RFH)cells,and tumor-burdened immunodeficiency mice in vivo.RESULTS The ectopic overexpression of Cks1b in human lung cancer cells induces chemoresistance of the cells to CDDP and DOX,but not3-COA,through mechanisms independent of its canonical Skp2-p27 pathway.Further dissection with application of shR NA and selective inhibitors reveals that Hsp90 and MEK1/2 are the critical components of the non-canonical pathways responsible for the Cks1b-induced chemoresistance.Interestingly,inhibition of either Hsp90 or MEK1/2rendered a similar magnitude of antitumor activity by resensitization of the chemoresistant Cks1b-OE cells to CDDP and DOX,suggesting that both Hsp90 and MEK1/2are essentialto Cks1b for induction of chemoresistance.IC50of 3-COA is 6.82μmol·L-1in H358 Cks1b and8.22μmol·L-1in H226 Cks1b,which were not significantly higher than those in H358 EV and H226 EV,respectively.Furthermore,3-COA mimicked PU-H71,a Hsp90-specific inhibitor,targeted Hsp90 and MEK to reduce the expression of their downstream,respectively.Importantly,compared with CDDP treatment,3-COA or 3-COA&CDDP signifi-cantly inhibited RFH cells in vitro.Moreover,3-COA or3-COA&CDDP significantly prolonged more survival for a H358 Cks1b-OE inducing tumor-burdened mice than PD98059(a MEK-specific inhibitor)in vivo.CONCLUSION Our data report for the first time that Cks1b employs Hsp90 and MEK1/2 pathways in lung cancer cells to develop chemoresistance and identify 3-COA as a potential antitumor drug for clinical treatment of chemoresistant lung cancer.
