Small cell lung cancer (SCLC) stands as one of the most lethal malignancies, characterized by a grim diagnosis and prognosis. The emergence of multi-drug resistance poses a significant hurdle to effective therapy. Although previous studies have implicated the long noncoding RNA LYPLAL1-DT in the tumorigenesis of SCLC, the precise role of the highly expressed LYPLAL1-DT in SCLC chemoresistance and the underlying mechanism remain inadequately understood. cDDP-, VP-16- and PTX-resistant SCLC cells lines were established. The viabilities of SCLC cells were assessed by CCK-8 assay in vitro and xenograft tumor formation assay in vivo. Apoptosis was evaluated by FACS, Western blot and JC-1 fluorescence staining, while autophagy was explored via autophagic flux detection under confocal microscopy and autophagic vacuole investigation under transmission electron microscopy (TEM). The functional role and mechanism of LYPLAL1-DT were further investigated by gain- and loss-of-function assays in vitro. Furthermore, the therapeutic efficacy of the combination of venetoclax and HCQ with cDDP, VP-16 or PTX was evaluated by cell line, cell-derived xenograft (CDX) and patient-derived xenograft (PDX) mice model. Our findings revealed that LYPLAL1-DT is upregulated in chemoresistant SCLC cell lines. Gain- and loss-of-function assays demonstrated that LYPLAL1-DT impairs sensitivity to cDDP, VP-16, or PTX both in vitro and in vivo. Overexpression of LYPLAL1-DT significantly enhanced autophagy and inhibited apoptosis in SCLC cells. Further analyses, including RIP and RNA pull-down assays, revealed that LYPLAL1-DT promotes the expression of BCL2 by sponging miR-204-5p and is implicated in the assembly of the autophagy-specific complex (BECN1/PtdIns3K complex). Combining venetoclax and HCQ with cDDP, VP-16, or PTX effectively mitigated chemoresistance in SCLC cells and suppressed tumor growth in CDX and PDX models without inducing obvious toxic effects. Our findings demonstrate that upregulation of LYPLAL1-DT sequesters apoptosis through the LYPLAL1-DT/miR-204-5p/BCL2 axis and promotes autophagy by facilitating the assembly of the BECN1/PtdIns3K complex, thereby mediating multi-drug resistance of SCLC. The triple combination of venetoclax, HCQ, in conjunction with cDDP, VP-16 or PTX overcomes refractory SCLC, shedding light on a potential therapeutic target for combating SCLC chemoresistance.

中文翻译：

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克服 SCLC 中的多药耐药性：维奈托克和羟氯喹靶向 lncRNA LYPLAL1-DT/BCL2/BECN1 通路的协同方法


小细胞肺癌 （SCLC） 是最致命的恶性肿瘤之一，其特点是诊断和预后严峻。多重耐药性的出现对有效治疗构成了重大障碍。尽管先前的研究表明长链非编码 RNA LYPLAL1-DT 与 SCLC 的肿瘤发生有关，但高度表达的 LYPLAL1-DT 在 SCLC 化疗耐药中的确切作用和潜在机制仍不充分了解。建立了 cDDP-、VP-16 和 PTX 耐药的 SCLC 细胞系。通过体外 CCK-8 测定和体内异种移植肿瘤形成测定评估 SCLC 细胞的活力。通过 FACS、Western blot 和 JC-1 荧光染色评估细胞凋亡，同时通过共聚焦显微镜下的自噬通量检测和透射电子显微镜 （TEM） 下的自噬液泡研究来探索自噬。通过体外功能获得和丧失测定进一步研究 LYPLAL1-DT 的功能作用和机制。此外，通过细胞系、细胞源性异种移植物 （CDX） 和患者来源的异种移植物 （PDX） 小鼠模型评价维奈托克和 HCQ 与 cDDP 、 VP-16 或 PTX 联合治疗的疗效。我们的研究结果显示，LYPLAL1-DT 在化疗耐药 SCLC 细胞系中上调。功能增益和丧失测定表明，LYPLAL1-DT 在体外和体内都会损害对 cDDP 、 VP-16 或 PTX 的敏感性。过表达 LYPLAL1-DT 显著增强 SCLC 细胞自噬并抑制细胞凋亡。进一步的分析，包括 RIP 和 RNA pull-down 测定，表明 LYPLAL1-DT 通过海绵 miR-204-5p 促进 BCL2 的表达，并与自噬特异性复合物 （BECN1/PtdIns3K 复合物） 的组装有关。 维奈托克和 HCQ 与 cDDP 、 VP-16 或 PTX 联合使用 CDX 和 PDX 模型可有效减轻 SCLC 细胞的化疗耐药性并抑制肿瘤生长，而不会诱导明显的毒性作用。我们的研究结果表明，LYPLAL1-DT 的上调通过 LYPLAL1-DT/miR-204-5p/BCL2 轴螯合细胞凋亡，并通过促进 BECN1/PtdIns3K 复合物的组装促进自噬，从而介导 SCLC 的多药耐药。venetoclax、HCQ 与 cDDP、VP-16 或 PTX 的三联疗法克服了难治性 SCLC，揭示了对抗 SCLC 化疗耐药性的潜在治疗靶点。