The role for alcohol-induced Golgi disorganization in the progression of prostate cancer

摘要 慢性酒精滥用和酒精中毒被认为是前列腺癌（PCa）进展的危险因素，但 其机制尚不清楚。目前的项目将解决临床医生提出的一个重要问题： 戒酒是PCa的重要治疗干预措施。在此之前，我们发现：（1）碎片化 高尔基复合体与前列腺癌的进展相关;（2）乙醇（EtOH）诱导高尔基体解体， 这是由最大的高尔基体基质蛋白giantin的二聚化受损引起的，这反过来又改变了高尔基体内的 一些高尔基体蛋白的定位。事实上，我们最近观察到，在雄激素反应性PCa细胞中， 诱导的高尔基体断裂导致糖原合成酶激酶β（GSK 3 β）从高尔基体易位到 细胞质中，随后激活HDAC 6-HSP 90-AR通路。此外，我们报告说，非肌肉 肌球蛋白IIA（NMIIA）运动蛋白迫使EtOH诱导的高尔基体破坏。此外，酒精诱导内质网 内质网（ER）应激和未折叠蛋白反应（UPR），它们是PCa进展的已知驱动因素; 然而，EtOH诱导的UPR在癌症中的机制仍在很大程度上未被揭示。在这里，我们发现，在低 传代LNCaP细胞，UPR传感器之一，ATF 6，在高尔基体中被S1 P和S2 P蛋白酶切割;然而， EtOH处理改变了S1 P和S2 P的高尔基体定位，将它们捕获在ER中并促进ATF 6 反式激活此外，EtOH诱导糖基转移酶MGAT 3从高尔基体易位到高尔基体。 细胞质随后降解。然而，与MGAT 3竞争N-聚糖的酶MGAT 5 分支，仍然保留在高尔基体中。这导致MGAT 5介导的促转移蛋白的糖基化 （包括基质蛋白酶和整合素）及其在细胞表面的过度表达。最后，我们发现， NMIIA功能防止酒精诱导的PCa细胞中的高尔基体片段化。这反过来又恢复了MGAT 3的内部- 高尔基体定位和减少整合素的表达。根据这些事实，我们建议检验假设 酒精通过高尔基体断裂加速PCa进展，这：（a）通过以下途径增强ER应激反应： 诱导ATF 6介导的UPR，和（B）刺激促转移蛋白的表达超过其异常表达， MGAT 5介导的糖基化。因此，靶向酒精诱导的高尔基体片段化在治疗上是重要的。 拟议研究的三个具体目标是：1）阐明酒精诱导激活的机制 通过确定酒精代谢物如何诱导高尔基体定位的S1 P和S2 P蛋白酶移位的ER应激 2）检查EtOH诱导的MGAT 5介导的糖基化在PCa进展中的作用;和3） 检查抑制或敲低NMIIA是否阻止EtOH诱导的高尔基体片段化并减弱 PCa细胞的侵袭性表型。该方法将包括各种体外和体内实验， EtOH处理的PCa细胞系、动物模型和来自饮酒PCa患者的临床样品。的 该研究目标的实现将扩大我们对前列腺癌基础生物学的理解 致癌作用，并阐明酒精的肿瘤促进作用的机制。

ABSTRACT Chronic alcohol abuse and alcoholism are considered risk factors for prostate cancer (PCa) progression, but the mechanism is unknown. The current project will address an important question raised by clinicians: whether alcohol abstinence is an important therapeutic intervention in PCa. Previously, we found that: (1) fragmentation of the Golgi complex correlates with the progression of PCa; (2) ethanol (EtOH) induces Golgi disorganization that is caused by the impaired dimerization of the largest Golgi matrix protein giantin, which, in turn, alters intra-Golgi localization of some Golgi proteins. Indeed, we recently observed that in androgen-responsive PCa cells, EtOH- induced Golgi fragmentation leads to translocation of glycogen synthase kinase β (GSK3β) from the Golgi to the cytoplasm, followed by the activation of HDAC6-HSP90-AR pathway. Additionally, we reported that non-muscle myosin IIA (NMIIA) motor protein forces EtOH-induced Golgi disruption. Also, alcohol induces endoplasmic reticulum (ER) stress and unfolded protein response (UPR), which are the known drivers of PCa advancement; however, the mechanism of EtOH-induced UPR in cancer remains largely uncovered. Here, we found that in low passage LNCaP cells, one of the UPR sensor, ATF6, is cleaved in Golgi by S1P and S2P proteases; however, EtOH treatment alters the Golgi localization of S1P and S2P, trapping them in the ER and facilitating ATF6 transactivation. Further, EtOH induces translocation of the glycosyltransferase MGAT3 from the Golgi to the cytoplasm followed by its degradation. However, MGAT5, the enzyme that competes with MGAT3 for N-glycan branching, is still retained in the Golgi. This results in MGAT5-mediated glycosylation of pro-metastatic proteins (including matriptase and integrins) and their overexpression at the cell surface. Finally, we detected that loss of NMIIA function prevents alcohol-induced Golgi fragmentation in PCa cells. This, in turn, recovers MGAT3’s intra- Golgi localization and reduces the expression of integrins. In light of these facts, we propose to test the hypothesis that alcohol accelerates PCa progression through Golgi fragmentation, which: (a) enhances ER stress response via induction of ATF6-mediated UPR, and (b) stimulates expression of pro-metastatic proteins over their abnormal MGAT5-mediated glycosylation. Hence, targeting alcohol-induced Golgi fragmentation is therapeutically important. The three specific aims of the proposed study are to: 1) elucidate the mechanism of alcohol-induced activation of ER stress by determining how alcohol metabolites induce translocation of Golgi localized S1P and S2P proteases to the ER; 2) examine the role of EtOH-induced MGAT5-mediated glycosylation in the progression of PCa; and 3) examine whether inhibition or knockdown of NMIIA prevents EtOH-induced Golgi fragmentation and attenuates the aggressive phenotype of PCa cells. The approach will include a variety of in vitro and in vivo experiments using EtOH-treated PCa cell lines, animal models and clinical samples from alcohol consuming PCa patients. The accomplishment of the goal of the proposed study would expand our understanding of the basic biology of PCa carcinogenesis, and elucidate the mechanisms of alcohol's tumor promotion action.