BACKGROUND Prostate cancer development involves various mechanisms, which are poorly understood but pointing to epithelial mesenchymal transition (EMT) as the key mechanism in progression to metastatic disease. ABI1, a member of WAVE complex and actin cytoskeleton regulator and adaptor protein, acts as tumor suppressor in prostate cancer but the role of ABI1 in EMT is not clear. METHODS To investigate the molecular mechanism by which loss of ABI1 contributes to tumor progression, we disrupted the ABI1 gene in the benign prostate epithelial RWPE-1 cell line and determined its phenotype. Levels of ABI1 expression in prostate organoid tumor cell lines was evaluated by Western blotting and RNA sequencing. ABI1 expression and its association with prostate tumor grade was evaluated in a TMA cohort of 505 patients and metastatic cell lines. RESULTS Low ABI1 expression is associated with biochemical recurrence, metastasis and death (p = 0.038). Moreover, ABI1 expression was significantly decreased in Gleason pattern 5 vs. pattern 4 (p = 0.0025) and 3 (p = 0.0012), indicating an association between low ABI1 expression and highly invasive prostate tumors. Disruption of ABI1 gene in RWPE-1 cell line resulted in gain of an invasive phenotype, which was characterized by a loss of cell-cell adhesion markers and increased migratory ability of RWPE-1 spheroids. Through RNA sequencing and protein expression analysis, we discovered that ABI1 loss leads to activation of non-canonical WNT signaling and EMT pathways, which are rescued by re-expression of ABI1. Furthermore, an increase in STAT3 phosphorylation upon ABI1 inactivation and the evidence of a high-affinity interaction between the FYN SH2 domain and ABI1 pY421 support a model in which ABI1 acts as a gatekeeper of non-canonical WNT-EMT pathway activation downstream of the FZD2 receptor. CONCLUSIONS ABI1 controls prostate tumor progression and epithelial plasticity through regulation of EMT-WNT pathway. Here we discovered that ABI1 inhibits EMT through suppressing FYN-STAT3 activation downstream from non-canonical WNT signaling thus providing a novel mechanism of prostate tumor suppression.

中文翻译：

---

Abi1丢失通过激活EMT和非经典WNT信号传导来驱动前列腺癌的发生。

背景技术前列腺癌的发展涉及多种机制，人们对其了解甚少，但指出上皮间质转化（EMT）是进展为转移性疾病的关键机制。ABI1是WAVE复合物和肌动蛋白细胞骨架调节剂和衔接蛋白的成员，在前列腺癌中起着抑癌作用，但ABI1在EMT中的作用尚不清楚。方法为了研究ABI1缺失导致肿瘤进展的分子机制，我们破坏了前列腺良性上皮RWPE-1细胞系中的ABI1基因并确定了其表型。通过蛋白质印迹和RNA测序评估前列腺类器官肿瘤细胞系中ABI1表达的水平。在505位患者和转移性细胞系的TMA队列中评估了ABI1表达及其与前列腺肿瘤等级的关系。结果ABI1低表达与生化复发，转移和死亡相关（p = 0.038）。此外，格里森模式5与模式4（p = 0.0025）和模式3（p = 0.0012）相比，ABI1表达显着降低，表明低ABI1表达与高侵袭性前列腺肿瘤之间存在关联。RWPE-1细胞系中ABI1基因的破坏导致侵袭性表型的获得，其特征是细胞-细胞粘附标记的丧失和RWPE-1球体的迁移能力增强。通过RNA测序和蛋白质表达分析，我们发现ABI1丢失导致非典型WNT信号和EMT通路的激活，这可以通过重新表达ABI1来挽救。此外，ABI1失活后STAT3磷酸化的增加以及FYN SH2域与ABI1 pY421之间的高亲和力相互作用的证据支持了这样一种模型，其中ABI1充当FZD2受体下游非经典WNT-EMT途径激活的守门人。结论ABI1通过调节EMT-WNT通路来控制前列腺肿瘤的进展和上皮可塑性。在这里，我们发现ABI1通过抑制非经典WNT信号下游的FYN-STAT3激活来抑制EMT，从而提供了一种前列腺肿瘤抑制的新机制。