PO.MCB03.03 · 分子与细胞生物学
破坏中心粒生物发生调控因子Cenpj通过p53依赖性DNA损伤修复和凋亡通路降低口腔癌易感性
Disruption of Cenpj, a centriole biogenesis regulator, diminishes oral cancer susceptibility through p53-dependent DNA-damage repair and apoptosis pathways
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摘要 Abstract
中文摘要
中心体P4.1相关蛋白（CPAP；基因：CENPJ）是一种微管结合的中心粒蛋白，其突变可导致人类小头畸形（MCP）。虽然已知CPAP功能障碍会导致中心体异常和基因组不稳定，但其对肿瘤起始和进展的影响在很大程度上尚不清楚。我们近期的报道显示，CPAP调控内吞囊泡运输功能以及表皮生长因子受体（EGFR）稳态和信号动态。CPAP耗竭赋予人口腔鳞状细胞癌（OSCC）细胞系上皮-间质转化（EMT）表型，并分别在体外和异种移植模型中增强了EGFR依赖性的侵袭和致瘤特性。在此，我们采用携带Cenpj亚效等位基因的小鼠模型（表现出侏儒和小头畸形表型，即MCP小鼠），以确定CPAP功能对EGFR水平和化学致癌物诱导的口腔肿瘤发生的影响。与人OSCC细胞系类似，来自MCP小鼠的成纤维细胞和舌上皮类器官表现出囊泡运输功能缺陷和EGFR蛋白水平的显著升高。然而，令我们惊讶的是，与野生型对照相比，MCP小鼠对4-硝基喹啉1-氧化物（4NQO）诱导的口腔肿瘤发生的易感性降低。在肿瘤进展的所有阶段，MCP小鼠的上皮细胞增殖和最终的肿瘤负荷都显著更低。用DNA损伤诱导剂处理的舌成纤维细胞和上皮类器官被用于确定Cenpj亚效小鼠肿瘤易感性降低的分子机制。这些来自MCP小鼠的细胞对DNA损伤高度敏感，并表现出p53以及DNA损伤修复（DDR）和凋亡通路的更高激活。例如，与携带WT等位基因的细胞相比，携带Cenpj亚效等位基因的细胞中gamma-H2AX和裂解型caspase-3水平以及凋亡性死亡显著更高。我们正在进行的研究聚焦于确定CPAP介导的EGFR稳态和中心粒功能如何在口腔肿瘤发生的不同阶段影响基因毒性和上皮细胞转化。总体而言，我们的发现首次揭示了关键的中心粒生物发生和小头畸形相关蛋白在基因毒性应激下肿瘤起始和进展中的作用，有望有助于为OSCC设计新的靶向治疗。
查看英文原文 English abstract
Mutations in centrosomal P4.1-associated protein (CPAP; Gene: CENPJ), a microtubule-bindingcentriolar protein, can lead to microcephaly (MCP) in humans. While CPAP dysfunction is knownto cause centrosome aberrations and genomic instability, its impact on tumor initiation andprogression is largely unknown. Our recent reports showed that CPAP regulates endocyticvesicular transport function and epidermal growth factor receptor (EGFR) homeostasis andsignaling dynamics. CPAP depletion endows human oral squamous cell carcinoma (OSCC) celllines with epithelial-mesenchymal transition (EMT) phenotype, and enhanced EGFR-dependentinvasive and tumorigenic properties in vitro and in a xenotransplant model, respectively. Here, weemployed a mouse model with hypomorphic allele of Cenpj , which shows dwarfism andmicrocephaly phenotype (MCP mice), to determine the impact of CPAP function on EGFR levelsand chemical carcinogen-induced oral tumorigenesis. Similar to human OSCC cell lines,fibroblasts, and tongue epithelium organoids from MCP mice exhibited defective vesiculartransport function and markedly increased EGFR protein levels. However, to our surprise, MCPmice exhibited diminished susceptibility to 4-Nitroquinoline 1-oxide (4NQO) -induced oraltumorigenesis as compared to their wild-type counterparts. Epithelial cell proliferation at all stagesof tumor progression and the eventual tumor burden were profoundly lower in MCP mice. Tonguefibroblasts and epithelial organoids treated with DNA damage-inducing agents were used todetermine the molecular mechanism(s) of reduced tumor susceptibility of Cenpj hypomorphicmice. These cells from MCP mice were highly susceptible to DNA damage and showed higheractivation of p53 and DNA-damage repair (DDR)- and apoptotic- pathways. For instance, gamma-H2AX and cleaved caspase-3 levels, and apoptotic death were significantly higher in cells withhypomorphic allele of Cenpj as compared to cells with WT allele. Our ongoing studies are focusedon determining how CPAP-mediated EGFR homeostasis and centriolar function impactgenotoxicity and epithelial cell transformation at different stages of oral tumorigenesis. Overall,our findings, for the first time, show a role for critical centriole biogenesis and microcephaly-associated protein in tumor initiation and progression under genotoxic stress and are expected tohelp design novel targeted therapies for OSCC.
利益披露 Disclosure
M. Bhattacharjee, None..
H. Dave, None.