Worst Thomas Stefan, Meyer Yannic, Gottschalt Maria, Weis Cleo-Aron, von Hardenberg Jost, Frank Christine, Steidler Annette, Michel Maurice Stephan, Erben Philipp
Department of Urology, Mannheim Medical Center, University of Heidelberg, D-68167 Mannheim, Germany.
Institute of Pathology, Mannheim Medical Center, University of Heidelberg, D-68167 Mannheim, Germany.
Int J Oncol. 2017 Mar;50(3):920-932. doi: 10.3892/ijo.2017.3872. Epub 2017 Feb 10.
Paracrine and long-range signaling via extracellular vesicles, such as exosomes and microvesicles, is deemed crucial for tumorigenesis, invasion and spread of solid tumors. The ESCRT machinery (endosomal sorting complexes required for transport) and Rab-proteins act as key players in vesicular trafficking and secretion. Yet, their role in prostate cancer (PCa) is unknown. Therefore, this study aimed to elucidate the relevance of these components in PCa. In silico reanalysis of genes with known involvement in vesicular trafficking and secretion in an existing microarray dataset revealed low expression of RAB27A, RAB27B and VPS36 to be predictive for reduced BCR-free survival in patients with localized PCa (p=0.033, 0.025 and 0.005). In the same microarray dataset underexpression of RAB27A, RAB27B and VPS36 was seen in distant metastases (p<0.001; p=0.003; p<0.001). This was consistent in two further microarray datasets. qRT-PCR-validation in two independent cohorts of PCa specimens (n=90) showed low expression of VPS36 in PCa tissue (p=0.023), especially in castration-resistant tumors (p=0.002). In all five datasets there were significant correlations between the expression of at least two of the candidates. Upon knockdown of VPS36 an increase of RAB27A and RAB27B expression, but not vice versa, was observed in both prostate and breast cancer cells (PC3, MDA-MB‑231). In PC3 cell knockdown of RAB27B and VPS36 dramatically reduced colony formation (-52.2%, p<0.001; -71.1%, p<0.001) and, controversial to reports in other tumor entities, increased the release of extracellular particles (+25.3%, p=0.014; +45.6%, p<0.001). Taken together RAB27A, RAB27B and VPS36 are frequently underexpressed in advanced PCa and are inversely correlated with PCa outcome. There seems to be a close relationship in the expression of RAB27A, RAB27B and VPS36, with RAB27A and RAB27B being dependent on VPS36. Changes in colony formation and particle release upon RNAi indicate an involvement in paracrine cell-cell communication.
通过细胞外囊泡（如外泌体和微囊泡）进行的旁分泌和远程信号传导被认为对实体瘤的发生、侵袭和扩散至关重要。ESCRT机制（运输所需的内体分选复合体）和Rab蛋白在囊泡运输和分泌中起关键作用。然而，它们在前列腺癌（PCa）中的作用尚不清楚。因此，本研究旨在阐明这些成分在PCa中的相关性。对现有微阵列数据集中已知参与囊泡运输和分泌的基因进行计算机再分析，结果显示RAB27A、RAB27B和VPS36的低表达可预测局限性PCa患者无生化复发生存期的缩短（p=0.033、0.025和0.005）。在同一微阵列数据集中，远处转移灶中可见RAB27A、RAB27B和VPS36的表达下调（p<0.001；p=0.003；p<0.001）。另外两个微阵列数据集也得到了一致的结果。在两个独立的PCa标本队列（n=90）中进行的qRT-PCR验证显示，PCa组织中VPS36表达较低（p=0.023），尤其是在去势抵抗性肿瘤中（p=0.002）。在所有五个数据集中，至少两个候选基因的表达之间存在显著相关性。在前列腺癌细胞和乳腺癌细胞（PC3、MDA-MB‑231）中敲低VPS36后，观察到RAB27A和RAB27B表达增加，但反之则不然。在PC3细胞中敲低RAB27B和VPS36可显著减少集落形成（-52.2%，p<0.001；-71.1%，p<0.001），并且与其他肿瘤实体的报道相反，增加了细胞外颗粒的释放（+25.3%，p=0.014；+45.6%，p<0.001）。综上所述，RAB27A、RAB27B和VPS36在晚期PCa中经常低表达，并且与PCa的预后呈负相关。RAB27A、RAB27B和VPS36的表达之间似乎存在密切关系，其中RAB27A和RAB27B依赖于VPS36。RNA干扰后集落形成和颗粒释放的变化表明其参与了旁分泌细胞间通讯。
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