Epithelial ovarian cancer (EOC) is the leading cause of death among all gynecological cancers. Morusin, a prenylated flavonoid extracted from the root bark of Morus australis, has been reported to exhibit anti-tumor activity against various human cancers except EOC. In the present study, we explored the potential anti-cancer activity of morusin against EOC in vitro and in vivo and possible underlying mechanisms for the first time. We first found that morusin effectively inhibited EOC cell proliferation and survival in vitro and suppressed tumor growth in vivo. Then we observed that treatment of EOC cells with morusin resulted in paraptosis-like cell death, a novel mode of non-apoptotic programmed cell death that is characterized by extensive cytoplasmic vacuolation due to dilation of the endoplasmic reticulum (ER) and mitochondria and lack of apoptotic hallmarks. In addition, we discovered that morusin induced obvious increase in mitochondrial Ca²⁺ levels, accumulation of ER stress markers, generation of reactive oxygen species (ROS), and loss of mitochondrial membrane potential (Δψm) in EOC cells. Furthermore, pretreatment with 4, 4′-diisothiocyanostilbene-2, 2′-disulfonic acid (DIDS), a chemical inhibitor of voltage-dependent anion channel (VDAC) on the outer mitochondrial membrane, effectively inhibited mitochondrial Ca²⁺ influx, cytoplasmic vacuolation and cell death induced by morusin in EOC cells. Moreover, DIDS pretreatment also suppressed morusin-induced accumulation of ER stress markers, ROS production and depletion of Δψm. Consistently, tumor xenograft assays showed that co-treatment with DIDS partially reversed the inhibitory effects of morusin on tumor growth in vivo and inhibited the increased levels of ER stress markers induced by morusin in tumor tissues. Collectively, our results suggest that VDAC-mediated Ca²⁺ influx into mitochondria and subsequent mitochondrial Ca²⁺ overload contribute to mitochondrial swelling and dysfunction, leading to morusin-induced paraptosis-like cell death in EOC. This study may provide alternative therapeutic strategies for EOC exhibiting resistance to apoptosis.

上皮性卵巢癌（EOC）是所有妇科癌症中主要的死亡原因。桑树素是从桑树根皮提取的异戊烯黄酮，据报道对除EOC以外的多种人类癌症均表现出抗肿瘤活性。在本研究中，我们首次探索了莫鲁辛在体外和体内对EOC的潜在抗癌活性以及可能的潜在机制。我们首先发现，morusin在体外可有效抑制EOC细胞的增殖和存活，并在体内抑制肿瘤的生长。然后，我们观察到用桑皮蛋白处理EOC细胞会导致麻痹样细胞死亡，这是一种新的非凋亡程序性细胞死亡模式，其特征在于由于内质网（ER）和线粒体的扩张而引起的广泛胞质空泡化以及缺乏凋亡标志。此外，我们发现桑rus蛋白在EOC细胞中诱导线粒体Ca ²⁺含量，ER应激标志物的积累，活性氧（ROS）的产生以及线粒体膜电位（Δψm）的损失明显增加。此外，用4、4'-二异硫氰基噻吩-2、2'-二磺酸（DIDS）（线粒体外膜上的电压依赖性阴离子通道（VDAC）的化学抑制剂）进行预处理可有效抑制线粒体Ca ²⁺桑皮蛋白在EOC细胞中诱导的细胞内流，细胞质空泡化和细胞死亡。此外，DIDS预处理还抑制了莫鲁沙因诱导的ER应激标志物的积累，ROS的产生和Δψm的消耗。一致地，肿瘤异种移植测定法显示，与DIDS的共同治疗部分逆转了莫鲁辛在体内对肿瘤生长的抑制作用，并抑制了莫鲁辛在肿瘤组织中诱导的ER应激标志物水平升高。总体而言，我们的结果表明，VDAC介导的Ca ²⁺流入线粒体及随后的线粒体Ca ^2+中。超负荷导致线粒体肿胀和功能障碍，导致EOC中由morusin诱导的类麻痹样细胞死亡。这项研究可能为EOC表现出对细胞凋亡的抵抗力提供​​替代治疗策略。