PO.TB03.03 · 肿瘤生物学
血影蛋白SPTAN1缺失触发基因组不稳定性和膀胱癌肿瘤生长
Spectrin SPTAN1 loss triggers genome instability and tumor growth in bladder cancer
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
血影蛋白αII（SPTAN1）是一种细胞骨架蛋白，在肌动蛋白丝组织和染色体分离中发挥重要作用。血影蛋白网络的改变被发现会影响细胞分裂并增强肿瘤进展。通过分析TCGA数据库的癌症基因组学数据，在肌层浸润性膀胱癌（MIBC，膀胱癌中最具侵袭性的类型）患者中频繁检测到血影蛋白基因SPTAN1的沉默突变及其下调。为研究血影蛋白αII缺失在MIBC发生发展中的可能作用，我们建立了稳定的MB49细胞克隆（SPTAN1-KD），其组成型表达SPTAN1特异性shRNA，从而导致SPTAN1表达下调。在SPTAN1-KD细胞中发现了带有微核的多核细胞，这些细胞伴有γH2AX和pCHK2的强染色，提示SPTAN1缺失触发了DNA损伤和基因组不稳定性。有趣的是，这些细胞可通过下调cGAS-STING通路逃避基因组危机诱导的细胞死亡，这是在具有基因组不稳定性的转移性癌细胞中经常发现的一种机制。MTT法进行的细胞增殖实验显示，与转染pLKO空载体的对照细胞或亲本细胞相比，SPTAN1-KD细胞的生长速率增强。异种移植肿瘤模型也证实了SPTAN1-KD细胞形成的病灶具有更高的肿瘤生长速率。转录组分析表明，SPTAN1-KD细胞中若干与T细胞耗竭、脂质代谢和ECM重塑相关的通路上调，同时与免疫监视相关的通路下调。因此，我们的研究提示SPTAN缺失通过诱导基因组不稳定性和细胞增殖发挥推动癌症进展的驱动作用。SPTAN缺失还可通过转录重编程触发免疫编辑来增强癌症存活。
查看英文原文 English abstract
Spectrin alphaII (SPTAN1) is a cytoskeletal protein which plays important roles in actin filament organization and chromosome segregation. Alterations in spectrin network was found to influence cell division and enhance tumor progression. By analyzing cancer genomics data from TCGA databank, silent mutations in spectrin gene SPTAN1 and its down-regulation were frequently detected in patients with muscle invasive bladder cancer (MIBC), the most aggressive cancer type of bladder cancer. To investigate the possible role of spectrin alphaII loss in MIBC development, we established stable MB49 cell clones (SPTAN1-KD) which constitutively express SPTAN1-specific shRNAs, leading to down-regulation of SPTAN1 expression. Multinucleated cells with micronuclei were found in SPTAN1-KD cells which were associated with strong staining of gamma H 2AX and pCHK2, suggesting DNA damage and genome instability triggered by SPTAN1 loss. Interestingly, these cells can escape the genome crisis-induced cell death by down-regulating the cGAS-STING pathways, a mechanism frequently found in metastatic cancer cells with genome instability. Cell proliferation assay by MTT assay revealed enhanced growth rate in SPTAN1-KD cells as compared to control cells transfected with pLKO empty vector or the parental cells. Xenografted tumor model also confirmed higher tumor growth rate in lesions formed by SPTAN1-KD cells Transcriptome analysis indicated up-regulation of several pathways involved in T cell exhaustion, lipid metabolism and ECM remodeling in SPTAN1-KD cells, which associated with down-regulation of pathways related to immune surveillance. Our study therefore suggests that SPTAN loss functions as a driving force to promote cancer progression by inducing genome instability and cell proliferation. SPTAN loss can also enhance cancer survival by triggering immune editing through transcriptional reprograming.
利益披露 Disclosure
J. Sheu, None..
C. Su, None.