PRKCD基因在t(8;21)白血病中的转录调控机制及对白血病发病的影响

The dominant negative repressive effects of AML1-ETO (AE) on AML1 target genes are considered as the major pathogenic mechanism of t(8;21) AML. Identification of the key target genes of AE and elucidation of their biological functions are essential for developing novel therapeutic strategies against t(8;21) leukemia. Our previous studies found that the expression of PRKCD was specially downregulated in t(8;21) leukemia samples as compared with non-t(8;21) leukemia samples. By performing bioinformatics analysis, we identified several putative AML1 and KLF4 binding sites within the promoter region of PRKCD, suggesting that the expression of PRKCD was negatively regulated by AE and KLF4 might also contribute to controlling PRKCD transcription. Further studies revealed that PRKCD were significantly upregulated during the process of cell differentiation and apoptosis induced by a pan-HDACi (sodium phenylbutyrate). Based on these findings, the current proposal is designed to elucidate whether AE promotes t(8;21) leukemia through inhibiting PRKCD gene transcription and to determine whether inducing PRKCD gene expression may be developed as a potent therapeutic strategy to treat t(8;21) leukemia. Data generated will not only further our understanding of the pathogenesis of t(8;21) leukemia, they will also facilitate the development of novel effective therapy against the AML with t(8;21) translocation.

AML1-ETO(AE)对AML1靶基因的负显性抑制作用被认为是t(8;21)白血病主要发病机制。寻找AE下游关键基因，阐明其生物学功能，将有助于为该型白血病找到新的靶向干预途径。我们前期研究发现，PRKCD显著低表达于t(8;21)白血病细胞，且该基因启动子区存在多个转录因子AML1和KLF4的潜在结合位点，提示该型白血病细胞中PRKCD转录可能受到AE的负性调控及KLF4的联合调控。随后，我们发现HDAC抑制剂诱导t(8;21)白血病细胞分化、凋亡过程中，PRKCD表达显著上调，提示该基因可能参与了白血病细胞的分化和凋亡过程。本项目以AML1、AE、KLF4对PRKCD的转录调控为切入点，研究AE是否通过抑制PRKCD转录促进t(8;21)白血病发生，进一步探索诱导PRKCD表达能否成为该型白血病治疗的新策略。本项目将有助于进一步揭示t(8;21)白血病的发病机制及潜在的靶向干预途径。

AML1-ETO对下游靶基因的负显性抑制作用被认为是t(8;21)白血病的主要发病机制。寻找AML1-ETO下游关键基因，阐明其生物学功能，将有助于为该型白血病提供新的治疗思路。本课题组前期研究发现，prkcd基因在t(8;21)白血病中特异性低表达，且参与了白血病细胞的分化凋亡过程。本项目在此基础上深入研究prkcd基因在t(8;21)白血病中的生物学功能以及AML1-ETO对prkcd的调控机制。本课题组研究发现prkcd在t(8;21)白血病细胞系和原代细胞中表达均显著低于其他亚型白血病细胞，且与病人预后不良存在密切关系。通过建立高表达细胞系进一步研究prkcd基因在该型白血病中的生物学功能，发现prkcd虽然不影响t(8;21)白血病细胞增殖、细胞周期分布、细胞凋亡以及分化抗原CD11b表达，但是显著增强t(8;21)白血病细胞对化疗药物阿糖胞苷的敏感性。prkcd基因编码产物为PKCδ激酶，本课题组进一步探索了PKCδ激酶激动剂PEP005与化疗药物联用是否具有协同杀伤白血病细胞的效应，发现PEP005可以显著增强t(8;21)白血病细胞对Ara-C的敏感性。机制研究发现，prkcd是AML1-ETO的靶基因，AML1-ETO结合于prkcd基因启动子区，直接转录抑制prkcd基因表达。本研究发现了AML1-ETO下游一个新的靶基因，并初步阐明了该基因在t(8;21)白血病中的生物学功能，有助于深入理解t(8,21)白血病的发病机制，并为该型白血病的靶向治疗提供了新思路。