PO.ET03.03 · 实验与分子治疗
GRN-300通过抑制HDAC-MEF2A-RAD51通路在BRCA2回复突变卵巢癌中恢复PARP抑制剂敏感性
GRN-300 restores PARP inhibitor sensitivity through inhibition of the HDAC-MEF2A-RAD51 pathway in BRCA2-revertant ovarian cancer
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
基因组不稳定性是癌症的一个标志。BRCA1和BRCA2等DNA修复基因的种系突变使个体易患肿瘤，但也赋予可被治疗利用的脆弱性。聚ADP核糖聚合酶（PARP）抑制剂选择性靶向由BRCA1/2突变引起的同源重组缺陷（HRD）肿瘤，并在卵巢癌中引发强烈反应。然而，耐药常通过继发性BRCA1/2回复突变而出现，这些突变部分恢复DNA修复功能，凸显了克服PARP抑制剂耐药策略的需求。盐诱导激酶2（SIK2）是一种AMPK相关激酶，为卵巢癌细胞增殖和转移所必需。选择性SIK2抑制剂GRN-300在HR功能正常的细胞中诱导DNA双链断裂（DSBs），并与PARP抑制剂协同产生合成致死。在此，我们研究GRN-300是否能在BRCA2回复突变卵巢癌中恢复PARP抑制剂敏感性。GRN-300显著降低了olaparib在PARP敏感的PEO1细胞（1.98降至0.64 μM）以及耐药的BRCA2回复突变PEO1-C4-2（6.87降至0.92 μM）和PEO4（3.47降至1.17 μM）卵巢癌细胞中的IC₅₀，恢复了反应性。GRN-300增加ROS生成，增强caspase-3/7激活，促进olaparib诱导的凋亡，同时抑制集落形成。在PEO1-C4-2异种移植瘤中，GRN-300联合olaparib显著抑制肿瘤生长而不影响体重。联合治疗增加gamma-H2AX和彗星尾形成，表明DNA损伤累积增强。机制上，GRN-300降低RAD51表达和RAD51病灶形成。SIK2抑制降低IIa类HDAC4/5/7的磷酸化，消除HDAC II类-MEF2A转录活性。ChIP-qPCR显示MEF2A与包括RAD51和RAD50在内的DNA修复基因调控区的结合减少，从而抑制由MRN复合体介导的DSB末端切除和链侵入。总之，GRN-300通过抑制HDAC-MEF2-RAD51通路在BRCA2回复突变卵巢癌中恢复PARP抑制剂敏感性，为克服PARP耐药提供了一种有前景的治疗策略。
查看英文原文 English abstract
Genomic instability is a hallmark of cancer. Germline mutations in DNA repair genes such as BRCA1 and BRCA2 predispose to tumor development but also confer vulnerabilities exploitable by therapy. Poly ADP-ribose polymerase (PARP) inhibitors selectively target tumors with homologous recombination deficiency (HRD) caused by BRCA1/2 mutations and elicit strong responses in ovarian cancer. However, resistance frequently emerges through secondary BRCA1/2 reversion mutations that partially restore DNA repair function, underscoring the need for strategies to overcome PARP inhibitor resistance. Salt-inducible kinase 2 (SIK2), an AMPK-related kinase, is required for ovarian cancer cell proliferation and metastasis. The selective SIK2 inhibitor GRN-300 induces DNA double-strand breaks (DSBs) in HR-proficient cells and synergizes with PARP inhibitors to produce synthetic lethality. Here, we investigated whether GRN-300 can restore PARP inhibitor sensitivity in BRCA2-revertant ovarian cancer. GRN-300 markedly reduced the IC₅₀ of olaparib in both PARP-sensitive PEO1 cells (1.98 to 0.64 µM) and resistant BRCA2-revertant PEO1-C4-2 (6.87 to 0.92 µM) and PEO4 (3.47 to 1.17 µM) ovarian cancer cells, restoring responsiveness. GRN-300 increased ROS production, enhanced caspase-3/7 activation, and promoted olaparib-induced apoptosis while suppressing colony formation. In PEO1-C4-2 xenografts, GRN-300 plus olaparib significantly inhibited tumor growth without affecting body weight. Combination treatment increased gamma-H2AX and comet-tail formation, indicating enhanced DNA damage accumulation. Mechanistically, GRN-300 reduced RAD51 expression and RAD51 foci formation. SIK2 inhibition decreased phosphorylation of class IIa HDAC4/5/7, abrogating HDAC class II-MEF2A transcriptional activity. ChIP-qPCR revealed reduced MEF2A binding to regulatory regions of DNA repair genes, including RAD51 and RAD50, thereby suppressing DSB end resection and strand invasion mediated by the MRN complex. In summary, GRN-300 restores PARP inhibitor sensitivity in BRCA2-revertant ovarian cancer through inhibition of the HDAC-MEF2-RAD51 pathway, providing a promising therapeutic strategy to overcome PARP resistance.
利益披露 Disclosure
C. Flores Suarez, None..
J. M. Santiago-O'Farrill, None..
W. Mao, None.