Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive and treatment-resistant malignancy. The lack of pathway-informed biomarkers hampers the development of rational diagnostics or therapies. Recently, the protein abnormal spindle-like microcephaly-associated (ASPM) was identified as a novel Wnt and stemness regulator in PDAC, while the pathogenic roles of its protein isoforms remain unclarified. We developed novel isoform-specific antibodies and genetic knockdown (KD) of putative ASPM isoforms, whereby we uncovered that the levels of ASPM isoform 1 (iI) and ASPM-iII are variably upregulated in PDAC cells. ASPM isoforms show remarkably different subcellular locations; specifically, ASPM-iI is exclusively localized to the cortical cytoplasm of PDAC cells, while ASPM-iII is predominantly expressed in cell nuclei. Mechanistically, ASPM-iI co-localizes with disheveled-2 and active β-catenin as well as the stemness marker aldehyde dehydrogenase-1 (ALDH-1), and its expression is indispensable for the Wnt activity, stemness, and the tumorigenicity of PDAC cells. By contrast, ASPM-iII selectively regulates the expression level of cyclin E and cell cycle progression in PDAC cells. The expression of ASPM-iI and ASPM-iII displays considerable intratumoral heterogeneity in PDAC tissues and only that of ASPM-iI was prognostically significant; it outperformed ALDH-1 staining and clinico-pathological variables in a multivariant analysis. Collectively, the distinct expression patterns and biological functions of ASPM isoforms may illuminate novel molecular mechanisms and prognosticators in PDAC and may pave the way for the development of therapies targeting this novel oncoprotein. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

中文翻译：

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ASPM亚型的差异分布及其在Wnt信号传导，细胞周期进展和胰腺癌预后中的作用。

胰腺导管腺癌（PDAC）是一种高度侵袭性和抗治疗性的恶性肿瘤。缺乏途径相关的生物标志物阻碍了合理的诊断或疗法的发展。最近，蛋白异常纺锤状小头相关（ASPM）被鉴定为PDAC中的新型Wnt和干性调节剂，而其蛋白同工型的致病作用仍不清楚。我们开发了新型同工型特异性抗体和推定ASPM同工型的基因敲除（KD），从而我们发现PDAC细胞中ASPM同工型1（iI）和ASPM-iII的水平可变地上调。ASPM同工型显示出明显不同的亚细胞位置；具体而言，ASPM-iI专门定位于PDAC细胞的皮质细胞质，而ASPM-iII主要在细胞核中表达。机械上，ASPM-iI与不整齐的2和活性β-连环蛋白以及干性标记醛脱氢酶-1（ALDH-1）共定位，其表达对于PDAC细胞的Wnt活性，干性和致瘤性必不可少。相比之下，ASPM-iII选择性调节PDAC细胞中细胞周期蛋白E的表达水平和细胞周期进程。ASPM-iI和ASPM-iII的表达在PDAC组织中显示出相当大的瘤内异质性，只有ASPM-iI的表达对预后具有重要意义。在多变量分析中，其表现优于ALDH-1染色和临床病理变量。总的来说，ASPM同工型的独特表达模式和生物学功能可能阐明了PDAC中的新型分子机制和预后因子，并可能为开发针对这种新型癌蛋白的疗法铺平了道路。©2019作者。John Wiley＆Sons Ltd代表大不列颠及爱尔兰病理学会出版的《病理学杂志》。