E3泛素连接酶Prp19促进肝癌细胞化疗抵抗及其分子机制研究

Drug resistance impairs the efficacy of current treatment in advanced HCC. Cell cycle arrest contributes to chemotherapeutic drugs-induced DNA damage repair of tumor cells, leading to drug resistance. Previous work demonstrated that HCC cells deficient in Prp19, one key repair factor of DNA damage, showed increased apoptosis under treatment with chemotherapeutic drugs of TACE regimen, as well as attenuated invasive capacity. Moreover Prp19 downregulation in HCC cells led to cell cycle progression and promoted in vivo growth of subcutaneous xenograft generated by HCC cells. Pilot study suggested that p21 might be the target of Prp19. In this program, the relationship between cell cycle and chemotherapeutic sensitivity as well as invasive ability in HCC cells will be studied. Biological activity of Prp19 on chemotherapeutic resistance of HCC will be attested in detail and verified by animal HCC models. Furthermore whether Prp19-induced chemotherapeutic resistance dependents on its modulation of cell cycle will be addressed. The related mechanism underlying cell cycle arrest and chemotherapeutic resistance rendered by Prp19 in HCC will be discussed in detail. This work will unravel the mechanism responsible for chemotherapeutic resistance of HCC and provide potential molecular targets that whose alteration increase the therapeutic efficacy of TACE.

药物抵抗降低进展期肝癌的治疗收益。细胞周期停滞有助于肿瘤细胞进行化疗药物诱导的DNA损伤修复，导致耐药发生。前期工作显示作为重要的DNA损伤修复因子，Prp19的下调可增加TACE中的化疗药物诱导的肝癌细胞的凋亡，并抑制其侵袭。此外Prp19下调导致肝癌细胞G1期的逃逸，促进裸鼠皮下瘤的生长。初步研究提示p21可能是Prp19的作用靶点。本课题将进一步明确肝癌细胞的细胞周期与化疗药物敏感性及侵袭能力的关系；详细探讨Prp19对肝癌细胞化疗抵抗的影响，并利用老鼠肝癌模型进行验证；分析Prp19诱导的肝癌细胞化疗抵抗是否依赖于其对细胞周期的调控。后续工作将着力于探索Prp19促进肝癌细胞周期停滞及化疗抵抗的相关机制。该课题有助于研究肝癌耐药机制，并提供提高TACE疗效的潜在分子靶点。

本课题证实肝癌细胞中抑制Prp19对缺氧条件下化疗药物的增敏作用。在肝癌细胞中Prp19与Cdc5L相互作用，并正向调控Cdc5L的表达。下调Prp19导致肝癌细胞G1期的逃逸。过表达Cdc5L 可逆转Prp19下调所引起的细胞周期的变化，提示Prp19通过Cdc5L参与细胞周期调控。后续机制研究阐明下调 Prp19 通过抑制翻译因子与Cdc5L 5'UTR 区域的结合而减弱Cdc5L mRNA 的翻译和促进Cdc5L 通过溶酶体途径的降解，从而协同调控Cdc5L的表达。本课题发现了Prp19参与肝癌耐药的潜在靶点CyclinD1及二者在DNA损伤时相似的变化趋势。考虑到诱导细胞周期停滞的药物的抗肿瘤活性，本课题有助于挖掘肝癌化疗耐药的潜在机制，并为Prp19作为新治疗靶点提供理论依据。 .