YAP在细胞衰老中的作用机制研究
发布时间：2018-11-06 10:10
【摘要】：细胞衰老是指细胞丧失增殖能力后进入的一种相对稳定的状态,端粒的缩短、化疗药处理引起的DNA损伤、癌基因的异常活化等都能诱导细胞衰老的发生。细胞衰老能够显著抑制细胞的生长,因此被认为是抑制肿瘤发生发展的重要因素之一。然而,越来越多的报道显示衰老细胞还具有促进肿瘤的作用。更具体地说,衰老的细胞在体内积累会诱发肿瘤,在化疗后的实体瘤中积累则有可能促进其周围细胞的增殖,以及通过SASP (senescence-associated sectroy phenotype)促进癌细胞耐药性的产生。因此,及时清除化疗后积累的衰老细胞或许有利于增强化疗的疗效。衰老的细胞可以通过向外分泌细胞因子,招募先天免疫细胞如巨噬细胞、中性粒细胞、自然杀伤细胞等将其清除,但是老年个体以及接受化疗的患者免疫系统都不完善,无法通过免疫系统达到清除的目的。此外,大多数细胞衰老后都非常稳定,这是由于它们具备抵抗凋亡的能力。因此,我们可以靶向衰老细胞的抗凋亡机制,从而诱导衰老细胞进入凋亡程序而被清除。为探究衰老细胞的抗凋亡机制,本研究建立了低浓度阿霉素(doxorubicin, DOX)诱导的细胞衰老模型。我们以衰老细胞的扁平增大表型为出发点,发现Hippo通路上的关键效应因子YAP在阿霉素诱导的衰老细胞中有明显的核累积现象,这很可能是由于衰老细胞与细胞外基质的接触面积增大而诱发的。YAP是促进肿瘤发生发展的癌基因,在许多肿瘤中都异常活化。尽管异常表达的癌基因会促进细胞衰老的发生,但是在本研究中高表达YAP或活化型突变YAPS127A都不能诱导细胞衰老的发生；敲降YAP后同样如此,反而促进了更多的细胞凋亡。因此,我们认为在阿霉素诱导的衰老细胞中,YAP的活化是衰老的结果,可以被癌细胞利用来抵抗凋亡。核内积累的YAP具有较高的转录活性,能够促进下游一系列靶基因的表达,如ANKRD1、CTGF以及CYR61等。抗凋亡蛋白survivin也是YAP的下游靶基因之一。Survivin作为细胞凋亡蛋白抑制因子家族的成员,在抵抗细胞凋亡过程中发挥着重要作用。本研究发现,在阿霉素诱导的衰老细胞中,YAP的活化促进了survivin的表达；经低浓度阿霉素诱导进入衰老状态的细胞,在加入靶向YAP的抑制剂verteporfin或者survivin的抑制剂YM155后,能够启动凋亡。综上,本研究表明,低浓度阿霉素诱导的衰老细胞依赖YAP的核内积累及活化来促进survivin的表达,从而抵抗细胞凋亡而维持其存活状态；低浓度的阿霉素可与YAP或survivin的抑制剂联用,以清除衰老细胞,达到增强化疗疗效和降低副作用的目的。
[Abstract]:Cell senescence is a relatively stable state in which cells lose their proliferative ability. Telomere shortening, DNA damage induced by chemotherapeutic agents and abnormal activation of oncogenes can induce cell senescence. Cell senescence can significantly inhibit the growth of cells, so it is considered to be one of the important factors to inhibit the development of tumor. However, more and more reports show that aging cells also play a role in tumor promotion. More specifically, the accumulation of aging cells in vivo may induce tumors, while accumulation in solid tumors after chemotherapy may promote the proliferation of peripheral cells and the production of drug resistance in cancer cells through SASP (senescence-associated sectroy phenotype). Therefore, the timely clearance of aging cells accumulated after chemotherapy may be beneficial to enhance the efficacy of chemotherapy. Aging cells can be cleared by secreting cytokines into the body, recruiting innate immune cells such as macrophages, neutrophils, natural killer cells, etc., but neither the elderly nor the patient receiving chemotherapy has a perfect immune system. It is impossible to clear through the immune system. In addition, most cells are very stable after aging, because they have the ability to resist apoptosis. Therefore, we can target the anti-apoptotic mechanism of aging cells, thus inducing aging cells to enter the process of apoptosis and be eliminated. In order to explore the anti-apoptosis mechanism of aging cells, a model of cell senescence induced by low concentration of adriamycin (doxorubicin, DOX) was established. Based on the flattened and enlarged phenotype of aging cells, we found that YAP, a key effector factor in the Hippo pathway, had a significant nuclear accumulation in adriamycin-induced aging cells. This is probably due to the increased contact area between aging cells and extracellular matrix (ECM). YAP is a oncogene that promotes tumorigenesis and development and is activated abnormally in many tumors. Although the abnormal expression of oncogene can promote cell senescence, neither overexpression of YAP nor activated mutant YAPS127A can induce cell senescence in this study. Therefore, we believe that in adriamycin-induced aging cells, the activation of YAP is the result of aging and can be used by cancer cells to resist apoptosis. YAP accumulated in the nucleus has high transcriptional activity and can promote the expression of a series of downstream target genes such as ANKRD1,CTGF and CYR61. Anti-apoptotic protein survivin is also one of the downstream target genes of YAP. As a member of the inhibitor of apoptosis protein family, Survivin plays an important role in the process of resistance to apoptosis. In this study, we found that the activation of YAP promoted the expression of survivin in adriamycin-induced aging cells. Cells in aging state induced by low concentration of doxorubicin could initiate apoptosis after adding verteporfin, an inhibitor of YAP, or YM155, an inhibitor of survivin. In conclusion, the results showed that the aging cells induced by low concentration of adriamycin depended on the accumulation and activation of YAP in nucleus to promote the expression of survivin, so as to resist the apoptosis of the cells and maintain their survival state. Low concentration of doxorubicin can be combined with YAP or survivin inhibitors to remove aging cells, enhance the efficacy of chemotherapy and reduce side effects.
【学位授予单位】：北京协和医学院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：R730.2
，
本文编号：2313976
[Abstract]:Cell senescence is a relatively stable state in which cells lose their proliferative ability. Telomere shortening, DNA damage induced by chemotherapeutic agents and abnormal activation of oncogenes can induce cell senescence. Cell senescence can significantly inhibit the growth of cells, so it is considered to be one of the important factors to inhibit the development of tumor. However, more and more reports show that aging cells also play a role in tumor promotion. More specifically, the accumulation of aging cells in vivo may induce tumors, while accumulation in solid tumors after chemotherapy may promote the proliferation of peripheral cells and the production of drug resistance in cancer cells through SASP (senescence-associated sectroy phenotype). Therefore, the timely clearance of aging cells accumulated after chemotherapy may be beneficial to enhance the efficacy of chemotherapy. Aging cells can be cleared by secreting cytokines into the body, recruiting innate immune cells such as macrophages, neutrophils, natural killer cells, etc., but neither the elderly nor the patient receiving chemotherapy has a perfect immune system. It is impossible to clear through the immune system. In addition, most cells are very stable after aging, because they have the ability to resist apoptosis. Therefore, we can target the anti-apoptotic mechanism of aging cells, thus inducing aging cells to enter the process of apoptosis and be eliminated. In order to explore the anti-apoptosis mechanism of aging cells, a model of cell senescence induced by low concentration of adriamycin (doxorubicin, DOX) was established. Based on the flattened and enlarged phenotype of aging cells, we found that YAP, a key effector factor in the Hippo pathway, had a significant nuclear accumulation in adriamycin-induced aging cells. This is probably due to the increased contact area between aging cells and extracellular matrix (ECM). YAP is a oncogene that promotes tumorigenesis and development and is activated abnormally in many tumors. Although the abnormal expression of oncogene can promote cell senescence, neither overexpression of YAP nor activated mutant YAPS127A can induce cell senescence in this study. Therefore, we believe that in adriamycin-induced aging cells, the activation of YAP is the result of aging and can be used by cancer cells to resist apoptosis. YAP accumulated in the nucleus has high transcriptional activity and can promote the expression of a series of downstream target genes such as ANKRD1,CTGF and CYR61. Anti-apoptotic protein survivin is also one of the downstream target genes of YAP. As a member of the inhibitor of apoptosis protein family, Survivin plays an important role in the process of resistance to apoptosis. In this study, we found that the activation of YAP promoted the expression of survivin in adriamycin-induced aging cells. Cells in aging state induced by low concentration of doxorubicin could initiate apoptosis after adding verteporfin, an inhibitor of YAP, or YM155, an inhibitor of survivin. In conclusion, the results showed that the aging cells induced by low concentration of adriamycin depended on the accumulation and activation of YAP in nucleus to promote the expression of survivin, so as to resist the apoptosis of the cells and maintain their survival state. Low concentration of doxorubicin can be combined with YAP or survivin inhibitors to remove aging cells, enhance the efficacy of chemotherapy and reduce side effects.
【学位授予单位】：北京协和医学院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：R730.2
，
本文编号：2313976
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