基于Hill动力学与Michaelis-Menten方程,建立理论模型研究发状分裂相关增强子1(Hairy and enhancer of split 1,Hes1)调控蛋白激酶B(Protein Kinase B,AKT)-鼠双微体2(Murine Double Minute2,MDM2)-抗癌基因p53(p53)-第10号染色体缺失...基于Hill动力学与Michaelis-Menten方程,建立理论模型研究发状分裂相关增强子1(Hairy and enhancer of split 1,Hes1)调控蛋白激酶B(Protein Kinase B,AKT)-鼠双微体2(Murine Double Minute2,MDM2)-抗癌基因p53(p53)-第10号染色体缺失的磷酸酶及张力蛋白同源的基因(Phosphatase and tensin homolog deleted on chromosome ten,PTEN)通路的一种物理机制.研究发现,Hes1通过与PTEN结合抑制PTEN表达,并调控AKT信号.表明了Hes1蛋白的合成,以及Hes1与PTEN相互作用调控AKT-MDM2-p53-PTEN通路信号,将会有效地控制细胞结果.Hes1作为AKT-MDM2-p53-PTEN信号通路中上游调节的重要因素,还可以在一定程度上通过影响p53蛋白功能,改变p53对肿瘤的抑制性.理论结果可用于预测Notch通路信号异常诱导的致癌性,并进一步揭示了Notch信号通路影响细胞AKT-MDM2-p53-PTEN通路的激活机制.展开更多
The p53 tumor suppressor is a key transcription factor regulating cellular pathways such as DNA repair, cell cycle, apoptosis, angiogenesis, and senescence. It acts as an important defense mechanism against cancer ons...The p53 tumor suppressor is a key transcription factor regulating cellular pathways such as DNA repair, cell cycle, apoptosis, angiogenesis, and senescence. It acts as an important defense mechanism against cancer onset and progression, and is negatively regulated by interaction with the oncoprotein MDM2. In human cancers, the TP53 gene is frequently mutated or deleted, or the wild-type p53 function is inhibited by high levels of MDM2, leading to downregulation of tumor suppressive p53 pathways. Thus, the inhibition of MDM2-p53 interaction presents an appealing therapeutic strategy for the treatment of cancer. However, recent studies have revealed the MDM2-p53 interaction to be more complex involving multiple levels of regulation by numerous cellular proteins and epigenetic mechanisms, making it imperative to reexamine this intricate interplay from a holistic viewpoint. This review aims to highlight the multifaceted network of molecules regulating the MDM2-p53 axis to better understand the pathway and exploit it for anticancer therapy.展开更多
OBJECTIVE To explore whether MDM2 transfection can alter the MDM2-p53 autoregulatory feedback loop so as to change the sensitivity of ovarian cancer cell lines to cisplatin. METHODS The ovarian cancer cell line A2780 ...OBJECTIVE To explore whether MDM2 transfection can alter the MDM2-p53 autoregulatory feedback loop so as to change the sensitivity of ovarian cancer cell lines to cisplatin. METHODS The ovarian cancer cell line A2780 expressing wild-type P53 and the ovarian cancer cell line SKOV-3 with the p53 null type were stably transfected with pCMV-MDM2 or pCMV as a control. The blocked expression of P53 was determined by Western blots. Cytotoxicity was assessed using the MTT assay and the trypan blue exclusion assay. Flow cytometry was used to detect changes in the cell cycle and removal of platinum -DNA adducts was measured by atomic absorption spec-troscopy. RESULTS (1) Parental A2780 and A2780-V cells (IC50= 15.14±1.39 μmol) have similar cisplatin sensitivities, whereas sensitivity to cisplatin in A2780-M cells (IC50=7.98±1.32 μmol) was 2 to 3 fold greater (P=0.001). The trypan blue exclusion assay demonstrated that cisplatin killed a higher percentage of A2780-M cells compared to A2780-V cells. There was no significant change following MDM2 transfection in SKOV-3 cells. (2) After cisplatin treatment, A2780-M cells showed a pronounced S-phase arrest, however, A2780 cells with the intact wild-type P53, arrested primarily at the G2/M transition. (3) Platinum uptake was similar for all of the A2780 cell lines after ciaplatin treatment, but the removal of plat-inum-DNA adducts was reduced in the A2780-M cells compared with A2780-V cells. CONCLUSION MDM2 increases cisplatin cytotoxicity in ovarian cancer cells by blocking the expression of p53 through the MDM2-p53 autoregulatory feedback loop.展开更多
文摘基于Hill动力学与Michaelis-Menten方程,建立理论模型研究发状分裂相关增强子1(Hairy and enhancer of split 1,Hes1)调控蛋白激酶B(Protein Kinase B,AKT)-鼠双微体2(Murine Double Minute2,MDM2)-抗癌基因p53(p53)-第10号染色体缺失的磷酸酶及张力蛋白同源的基因(Phosphatase and tensin homolog deleted on chromosome ten,PTEN)通路的一种物理机制.研究发现,Hes1通过与PTEN结合抑制PTEN表达,并调控AKT信号.表明了Hes1蛋白的合成,以及Hes1与PTEN相互作用调控AKT-MDM2-p53-PTEN通路信号,将会有效地控制细胞结果.Hes1作为AKT-MDM2-p53-PTEN信号通路中上游调节的重要因素,还可以在一定程度上通过影响p53蛋白功能,改变p53对肿瘤的抑制性.理论结果可用于预测Notch通路信号异常诱导的致癌性,并进一步揭示了Notch信号通路影响细胞AKT-MDM2-p53-PTEN通路的激活机制.
基金supported by the National Institutes of Health(NIH)grants R01CA112029 and R01CA121211a Susan G Komen Foundation grant BCTR0707731(to R.Z.)
文摘The p53 tumor suppressor is a key transcription factor regulating cellular pathways such as DNA repair, cell cycle, apoptosis, angiogenesis, and senescence. It acts as an important defense mechanism against cancer onset and progression, and is negatively regulated by interaction with the oncoprotein MDM2. In human cancers, the TP53 gene is frequently mutated or deleted, or the wild-type p53 function is inhibited by high levels of MDM2, leading to downregulation of tumor suppressive p53 pathways. Thus, the inhibition of MDM2-p53 interaction presents an appealing therapeutic strategy for the treatment of cancer. However, recent studies have revealed the MDM2-p53 interaction to be more complex involving multiple levels of regulation by numerous cellular proteins and epigenetic mechanisms, making it imperative to reexamine this intricate interplay from a holistic viewpoint. This review aims to highlight the multifaceted network of molecules regulating the MDM2-p53 axis to better understand the pathway and exploit it for anticancer therapy.
文摘OBJECTIVE To explore whether MDM2 transfection can alter the MDM2-p53 autoregulatory feedback loop so as to change the sensitivity of ovarian cancer cell lines to cisplatin. METHODS The ovarian cancer cell line A2780 expressing wild-type P53 and the ovarian cancer cell line SKOV-3 with the p53 null type were stably transfected with pCMV-MDM2 or pCMV as a control. The blocked expression of P53 was determined by Western blots. Cytotoxicity was assessed using the MTT assay and the trypan blue exclusion assay. Flow cytometry was used to detect changes in the cell cycle and removal of platinum -DNA adducts was measured by atomic absorption spec-troscopy. RESULTS (1) Parental A2780 and A2780-V cells (IC50= 15.14±1.39 μmol) have similar cisplatin sensitivities, whereas sensitivity to cisplatin in A2780-M cells (IC50=7.98±1.32 μmol) was 2 to 3 fold greater (P=0.001). The trypan blue exclusion assay demonstrated that cisplatin killed a higher percentage of A2780-M cells compared to A2780-V cells. There was no significant change following MDM2 transfection in SKOV-3 cells. (2) After cisplatin treatment, A2780-M cells showed a pronounced S-phase arrest, however, A2780 cells with the intact wild-type P53, arrested primarily at the G2/M transition. (3) Platinum uptake was similar for all of the A2780 cell lines after ciaplatin treatment, but the removal of plat-inum-DNA adducts was reduced in the A2780-M cells compared with A2780-V cells. CONCLUSION MDM2 increases cisplatin cytotoxicity in ovarian cancer cells by blocking the expression of p53 through the MDM2-p53 autoregulatory feedback loop.
