Sun Weichu, Sun Jingqi, Hu Wei, Luo Cong, Lu Zhongwei, He Fen, Zhao Hongyan, Zeng Xi, Cao Deliang, Li Junjun, Zhang Chang, Xia Jiliang
Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, Hunan, China.
Hunan Engineering Research Center for Early Diagnosis and Treatment of Liver Cancer, Hengyang Medical School, University of South China, Hengyang, Hunan, China.
Cancer Chemother Pharmacol. 2024 Dec 11;95(1):3. doi: 10.1007/s00280-024-04736-7.
Osteolysis is a common complication in patients with multiple myeloma (MM). Our previous studies have demonstrated that MM cells can promote osteoclast differentiation of macrophages. In this study, we explored the effect of sulforaphane (SFN), a natural NRF2 activator found in broccoli, on MM cell-induced osteoclast differentiation.
Conditional medium (CM) derived from MM cells was used to induce osteoclast differentiation, and TRAP staining was performed to examine osteoclast. Gene expression was detected by western blotting or real-time PCR. Cell counting and EdU staining were performed to test macrophage proliferation.
We showed that the CM of MM cells downregulated the expression of ferroportin1 (Fpn1), the only known iron exporter in vertebrate cells, thereby increasing cellular iron levels in murine macrophage cells RAW264.7. Deferoxamine (DFO), an iron chelator, effectively blocked MM cell CM-induced osteoclast differentiation and macrophage proliferation, suggesting that iron overload played a key role in these cellular events. Subsequent mechanistic investigations revealed that MM cell CM induced osteoclast differentiation and macrophage proliferation by activating the JNK/AP-1/NFATC1 pathway and PI3K/AKT pathway. SFN was found to increase Fpn1 expression, leading to decreased cellular iron levels in RAW264.7 cells activated by MM cell CM. Importantly, the osteoclast differentiation and macrophage proliferation induced by MM cell CM were significantly inhibited by SFN.
Altogether, our findings indicated that SFN inhibits MM cell-induced osteoclast differentiation and macrophage proliferation by elevating FPN1 levels. SFN could be a promising therapeutic strategy for MM-associated osteolysis.
骨溶解是多发性骨髓瘤（MM）患者常见的并发症。我们之前的研究表明，MM细胞可促进巨噬细胞向破骨细胞分化。在本研究中，我们探究了萝卜硫素（SFN）（一种在西兰花中发现的天然NRF2激活剂）对MM细胞诱导的破骨细胞分化的影响。
使用来自MM细胞的条件培养基（CM）诱导破骨细胞分化，并进行抗酒石酸酸性磷酸酶（TRAP）染色以检测破骨细胞。通过蛋白质免疫印迹或实时聚合酶链反应检测基因表达。进行细胞计数和5-乙炔基-2'-脱氧尿苷（EdU）染色以检测巨噬细胞增殖。
我们发现，MM细胞的CM下调了铁转运蛋白1（Fpn1）的表达，Fpn1是脊椎动物细胞中唯一已知的铁输出蛋白，从而增加了小鼠巨噬细胞RAW264.7中的细胞铁水平。铁螯合剂去铁胺（DFO）有效地阻断了MM细胞CM诱导的破骨细胞分化和巨噬细胞增殖，表明铁过载在这些细胞事件中起关键作用。随后的机制研究表明，MM细胞CM通过激活JNK/AP-1/NFATC1途径和PI3K/AKT途径诱导破骨细胞分化和巨噬细胞增殖。发现SFN可增加Fpn1表达，导致MM细胞CM激活的RAW264.7细胞中的细胞铁水平降低。重要的是，SFN显著抑制了MM细胞CM诱导的破骨细胞分化和巨噬细胞增殖。
总之，我们的研究结果表明，SFN通过提高FPN1水平抑制MM细胞诱导的破骨细胞分化和巨噬细胞增殖。SFN可能是治疗MM相关骨溶解的一种有前景的治疗策略。
