BACKGROUND Cell adhesion-mediated drug resistance (CAM-DR) is a major clinical problem that prevents successful treatment of multiple myeloma (MM). In particular, the expression levels of integrin β1 and its sub-cellular distribution (internalization and trafficking) are strongly associated with CAM-DR development. METHODS Development of an adhesion model of established MM cell lines and detection of Numbl and Integrinβ1 expression by Western Blot analysis. The interaction between Numbl and Integrinβ1 was assessed by a co-immunoprecipitation (CO-IP) method. Calcein AM assay was performed to investigate the levels of cell adhesion. Finally, the extent of CAM-DR in myeloma cells was measured using cell viability assay and flow cytometry analysis. RESULTS Our preliminary date suggest that Numbl is differentially expressed in a cell adhesion model of MM cell lines. In addition to binding to the phosphotyrosine-binding (PTB) domain, the carboxyl terminal of Numbl can also interact with integrin β1 to regulate the cell cycle by activating the pro-survival PI3K/AKT signaling pathway. This study intends to verify and elucidate the interaction between Numbl and integrin β1 and its functional outcome on CAM-DR. We have designed and developed a CAM-DR model using MM cells coated with either fibronectin or bone marrow stromal cells. We assessed whether Numbl influences cell-cycle progression and whether it, in turn, contributes to activation of PI3K/AKT signal pathway through the adjustment of its carboxyl end. Finally, we showed that the interaction of Numbl with integrin β1 promotes the formation of CAM-DR in MM cells. CONCLUSIONS Our findings elucidated the specific molecular mechanisms of CAM-DR induction and confirmed that Numbl is crucial for the development of CAM-DR in MM cells.

中文翻译：

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阐明在多发性骨髓瘤（MM）中细胞粘附介导的耐药性（CAM-DR）期间Numbl的表达和功能。

背景技术细胞粘附介导的耐药性（CAM-DR）是阻止成功治疗多发性骨髓瘤（MM）的主要临床问题。特别地，整联蛋白β1的表达水平及其亚细胞分布（内在化和运输）与CAM-DR的发展密切相关。方法建立建立的MM细胞系粘附模型，并通过Western Blot分析检测Numbl和整联蛋白β1的表达。Numbl和整联蛋白β1之间的相互作用通过免疫共沉淀（CO-IP）方法进行了评估。进行钙黄绿素AM测定以研究细胞粘附水平。最后，使用细胞活力测定和流式细胞仪分析测量骨髓瘤细胞中CAM-DR的程度。结果我们的初步数据表明，Numbl在MM细胞系的细胞粘附模型中差异表达。除了结合磷酸酪氨酸结合（PTB）结构域外，Numbl的羧基末端还可以与整联蛋白β1相互作用，通过激活存活前PI3K / AKT信号通路来调节细胞周期。本研究旨在验证和阐明Numbl和整联蛋白β1之间的相互作用及其在CAM-DR上的功能结果。我们已经设计并开发了使用涂有纤连蛋白或骨髓基质细胞的MM细胞的CAM-DR模型。我们评估了Numbl是否会影响细胞周期进程，以及它是否通过调节其羧基末端而反过来有助于激活PI3K / AKT信号通路。最后，我们发现Numbl与整联蛋白β1的相互作用促进了MM细胞中CAM-DR的形成。结论我们的发现阐明了CAM-DR诱导的特定分子机制，并证实Numbl对于MM细胞中CAM-DR的发展至关重要。