Primary effusion lymphoma (PEL) is a lymphogenic disorder associated with Kaposi's sarcoma-associated herpesvirus (KSHV) infection. Key to the survival and proliferation of PEL is the canonical NF-κB pathway, which becomes constitutively activated following overexpression of the viral oncoprotein KSHV vFLIP (ks-vFLIP). This arises from its capacity to form a complex with the modulatory subunit of the IκB kinase (IKK) kinase, IKKγ (or NEMO), resulting in the overproduction of proteins that promote cellular survival and prevent apoptosis, both of which are important drivers of tumorigenesis. Using a combination of cell-based and biophysical assays together with structural techniques, we showed that the observed resistance to cell death is largely independent of autophagy or major death receptor signaling pathways and demonstrated that direct targeting of the ks-vFLIP–IKKγ interaction both in cells and in vitro can be achieved using IKKγ-mimetic peptides. Our results further reveal that these peptides not only induce cell killing but also potently sensitize PEL to the proapoptotic agents tumor necrosis factor alpha and etoposide and are the first to confirm ks-vFLIP as a tractable target for the treatment of PEL and related disorders.

IMPORTANCE KSHV vFLIP (ks-vFLIP) has been shown to have a crucial role in cellular transformation, in which it is vital for the survival and proliferation of primary effusion lymphoma (PEL), an aggressive malignancy associated with infection that is resistant to the majority of chemotherapeutic drugs. It operates via subversion of the canonical NF-κB pathway, which requires a physical interaction between ks-vFLIP and the IKK kinase modulatory subunit IKKγ. While this interaction has been directly linked to protection against apoptosis, it is unclear whether the suppression of other cell death pathways implicated in ks-vFLIP pathogenesis is an additional contributor. We demonstrate that the interaction between ks-vFLIP and IKKγ is pivotal in conferring resistance to apoptosis. Additionally, we show that the ks-vFLIP–IKKγ complex can be disrupted using peptides leading to direct killing and the sensitization of PEL cells to proapoptotic agents. Our studies thus provide a framework for future therapeutic interventions.

原发性渗出性淋巴瘤 (PEL) 是一种与卡波西肉瘤相关疱疹病毒 (KSHV) 感染相关的淋巴疾病。PEL 存活和增殖的关键是典型的 NF-κB 途径，该途径在病毒癌蛋白 KSHV vFLIP (ks-vFLIP) 过表达后被组成型激活。这是因为它能够与 IκB 激酶 (IKK) 激酶的调节亚基 IKKγ (或 NEMO) 形成复合物，从而导致促进细胞存活和防止细胞凋亡的蛋白质过量产生，这两者都是肿瘤发生的重要驱动因素. 结合基于细胞和生物物理的分析以及结构技术，体外可以使用 IKKγ-模拟肽来实现。我们的研究结果进一步表明，这些肽不仅诱导细胞杀伤，而且有效地使 PEL 对促凋亡剂肿瘤坏死因子 α 和依托泊苷敏感，并且首次证实 ks-vFLIP 作为治疗 PEL 和相关疾病的易处理靶标。

重要性KSHV vFLIP (ks-vFLIP) 已被证明在细胞转化中起着至关重要的作用，其中它对原发性渗出性淋巴瘤 (PEL) 的存活和增殖至关重要，PEL 是一种与感染相关的侵袭性恶性肿瘤，对大多数化疗药物。它通过颠覆经典的 NF-κB 途径来发挥作用，这需要 ks-vFLIP 和 IKK 激酶调节亚基 IKKγ 之间的物理相互作用。虽然这种相互作用与防止细胞凋亡直接相关，但尚不清楚抑制与 ks-vFLIP 发病机制有关的其他细胞死亡途径是否是另一个因素。我们证明 ks-vFLIP 和 IKKγ 之间的相互作用对于赋予细胞凋亡抗性至关重要。此外，我们表明，可以使用导致直接杀伤和 PEL 细胞对促凋亡剂敏感的肽破坏 ks-vFLIP-IKKγ 复合物。因此，我们的研究为未来的治疗干预提供了一个框架。