Maspin (SERPINB5) is a potential tumor suppressor gene with pleiotropic biological activities, including regulation of cell proliferation, death, adhesion, migration and gene expression. Several studies indicate that nuclear localization is essential for maspin tumor suppression activity. We have previously shown that the EGFR activation leads to maspin nuclear localization in MCF-10A cells. The present study investigated which EGFR downstream signaling molecules are involved in maspin nuclear localization and explored a possible role of cell–cell contact in this process. MCF-10A cells were treated with pharmacological inhibitors against EGFR downstream pathways followed by EGF treatment. Maspin subcellular localization was determined by immunofluorescence. Proteomic and interactome analyses were conducted to identify maspin-binding proteins in EGF-treated cells only. To investigate the role of cell–cell contact these cells were either treated with chelating agents or plated on different cell densities. Maspin and E-cadherin subcellular localization was determined by immunofluorescence. We found that PI3K-Akt and JAK2-STAT3, but not MAP kinase pathway, regulate EGF-induced maspin nuclear accumulation in MCF-10A cells. We observed that maspin is predominantly nuclear in sparse cell culture, but it is redistributed to the cytoplasm in confluent cells even in the presence of EGF. Proteomic and interactome results suggest a role of maspin on post-transcriptional and translation regulation, protein folding and cell–cell adhesion. Maspin nuclear accumulation is determined by an interplay between EGFR (via PI3K-Akt and JAK2-STAT3 pathways) and cell–cell contact.

中文翻译：

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PI3K-AKT、JAK2-STAT3 通路和细胞间接触调节 maspin 亚细胞定位

Maspin (SERPINB5) 是一种潜在的肿瘤抑制基因，具有多效生物学活性，包括调节细胞增殖、死亡、粘附、迁移和基因表达。几项研究表明，核定位对于 maspin 肿瘤抑制活性至关重要。我们之前已经表明，EGFR 激活导致 MCF-10A 细胞中的 maspin 核定位。本研究调查了哪些 EGFR 下游信号分子参与了 maspin 核定位，并探索了细胞 - 细胞接触在此过程中的可能作用。MCF-10A 细胞用针对 EGFR 下游通路的药理学抑制剂处理，然后进行 EGF 处理。Maspin亚细胞定位通过免疫荧光测定。进行蛋白质组学和相互作用组分析以仅在 EGF 处理的细胞中鉴定 maspin 结合蛋白。为了研究细胞-细胞接触的作用，这些细胞要么用螯合剂处理，要么铺在不同的细胞密度上。Maspin和E-钙粘蛋白亚细胞定位通过免疫荧光测定。我们发现 PI3K-Akt 和 JAK2-STAT3，但不是 MAP 激酶途径，调节 EGF 诱导的 MCF-10A 细胞中的 maspin 核积累。我们观察到 maspin 在稀疏细胞培养物中主要是细胞核，但即使在存在 EGF 的情况下，它也会重新分布到汇合细胞的细胞质中。蛋白质组学和相互作用组结果表明 maspin 在转录后和翻译调控、蛋白质折叠和细胞-细胞粘附中的作用。