Myeloma light chains induce epithelial-mesenchymal transition in human renal proximal tubule epithelial cells
Myeloma light chains induce epithelial-mesenchymal transition in human renal proximal tubule epithelial cells
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DOI：
10.1093/ndt/gfm670
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发表时间：
2008-03-01
影响因子：
6.1
通讯作者：
Batuman, Vecihi
中科院分区：
文献类型：
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作者：
Li, Min;Hering-Smith, Kathleen S.;Batuman, Vecihi
背景资料。为探讨上皮-间充质转化(EMT)在多发性骨髓瘤肾小管间质纤维化中的作用，我们检测了骨髓瘤轻链(LCS)是否直接诱导人肾近端小管上皮细胞(PTECs)发生EMT。作为阳性对照，我们使用了转化生长因子-β1和环孢素A(CsA)，这两种已知的药物可以诱导PTECs发生EMT。人LC是从无肾小球受累证据的轻度肾功能不全的骨髓瘤患者的尿液中分离和纯化的。Kappa LC(25mM)作用于HK-2细胞72h。LCS诱导PTECs发生明显的细胞形态改变，并伴有促纤维化的转化生长因子-β1、FSP-1和细胞外基质成分的表达水平升高。应用半定量免疫印迹和RT-PCR方法观察到，持续暴露kappa-LCS后，PTEC中E-钙粘蛋白表达下降，而α-SMA表达增加。人血清白蛋白(HSA；160mM)对EMT相关分子表达的影响较小。中和转化生长因子-β1抗体可阻断CsA诱导的EMT，但对LC暴露的细胞无影响。P38MAPK干扰可显著抑制LC诱导的EMT及IL-6和MCP-1的分泌。使用骨形态发生蛋白-7或垂体腺苷环化酶激活多肽(PACAP)可诱导细胞聚集，并在LC期间和LC后融合细胞单层内重新获得E-钙粘蛋白的表达和肾近端小管上皮细胞的形态。这些结果表明LC是PTECs中EMT的直接刺激。LC诱导的EMT涉及多种细胞因子，受p38MAPK调控，但不依赖于转化生长因子-β1的作用。LC诱导的EMT可能是骨髓瘤相关肾损伤的重要机制，外源性PACAP可逆转。
Background. To determine the role of epithelial-mesenchymal transition (EMT) as a potential mechanism contributing to the characteristic tubulointerstitial renal fibrosis in multiple myeloma, we examined whether myeloma light chains (LCs) directly induce EMT in human renal proximal tubule epithelial cells (PTECs).Methods. As positive controls we used TGF-beta 1 and cyclosporine A (CsA), two agents known to induce EMT in PTECs. Human LCs were isolated and purified from the urine of myeloma patients with modest renal insufficiency without evidence of glomerular involvement. HK-2 cells were exposed to kappa LC (25 mu M) for periods up to 72 h.Results. LCs induced marked cellular morphological alterations in PTECs, accompanied with increased expression levels of profibrotic TGF-beta 1, FSP-1 and extracellular matrix components. Using semiquantitative immunoblotting and RT-PCR, we observed that the expression of E-cadherin decreased after 24 h, while the expression of alpha-SMA increased in PTEC after continuous exposure to kappa-LCs. Human serum albumin (HSA; 160 mu M) had less potent effect on the expression of EMT-related molecules. Neutralizing TGF-beta 1 antibody blocked CsA-induced EMT but had no effect on LC-exposed cells. LC-induced EMT and the secretions of IL-6 and MCP-1 were, however, markedly attenuated by p38 MAPK interference. The use of bone morphogenetic protein-7 or pituitary adenylate cyclase-activating polypeptide (PACAP) induced the formation of cell aggregates, and the reacquisition of E-cadherin expression and renal proximal tubule epithelial morphology within the confluent cell monolayer during and after LC exposure.Conclusions. These findings demonstrate that LC is a direct stimulus for EMT in PTECs. LC-induced EMT involved multiple cytokines, is modulated by p38 MAPK, but appeared independent of the action of TGF-beta 1. LC-induced EMT may be an important mechanism of kidney injury associated with myeloma and may be reversible upon the administration of exogenous PACAP.