Richter Mark, Dayaram Tajhal, Gilmartin Aidan G, Ganji Gopinath, Pemmasani Sandhya Kiran, Van Der Key Harjeet, Shohet Jason M, Donehower Lawrence A, Kumar Rakesh
Oncology R&D, GlaxoSmithKline, 1250 S. Collegeville Road, Collegeville, Pennsylvania, United States of America.
Department of Molecular Virology and Microbiology and Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America.
PLoS One. 2015 Feb 6;10(2):e0115635. doi: 10.1371/journal.pone.0115635. eCollection 2015.
The wild-type p53-induced phosphatase 1 (WIP1) is a serine/threonine phosphatase that negatively regulates multiple proteins involved in DNA damage response including p53, CHK2, Histone H2AX, and ATM, and it has been shown to be overexpressed or amplified in human cancers including breast and ovarian cancers. We examined WIP1 mRNA levels across multiple tumor types and found the highest levels in breast cancer, leukemia, medulloblastoma and neuroblastoma. Neuroblastoma is an exclusively TP53 wild type tumor at diagnosis and inhibition of p53 is required for tumorigenesis. Neuroblastomas in particular have previously been shown to have 17q amplification, harboring the WIP1 (PPM1D) gene and associated with poor clinical outcome. We therefore sought to determine whether inhibiting WIP1 with a selective antagonist, GSK2830371, can attenuate neuroblastoma cell growth through reactivation of p53 mediated tumor suppression. Neuroblastoma cell lines with wild-type TP53 alleles were highly sensitive to GSK2830371 treatment, while cell lines with mutant TP53 were resistant to GSK2830371. The majority of tested neuroblastoma cell lines with copy number gains of the PPM1D locus were also TP53 wild-type and sensitive to GSK2830371A; in contrast cell lines with no copy gain of PPM1D were mixed in their sensitivity to WIP1 inhibition, with the primary determinant being TP53 mutational status. Since WIP1 is involved in the cellular response to DNA damage and drugs used in neuroblastoma treatment induce apoptosis through DNA damage, we sought to determine whether GSK2830371 could act synergistically with standard of care chemotherapeutics. Treatment of wild-type TP53 neuroblastoma cell lines with both GSK2830371 and either doxorubicin or carboplatin resulted in enhanced cell death, mediated through caspase 3/7 induction, as compared to either agent alone. Our data suggests that WIP1 inhibition represents a novel therapeutic approach to neuroblastoma that could be integrated with current chemotherapeutic approaches.
野生型p53诱导的磷酸酶1（WIP1）是一种丝氨酸/苏氨酸磷酸酶，它对包括p53、CHK2、组蛋白H2AX和ATM在内的多种参与DNA损伤反应的蛋白质具有负调控作用，并且已证实在包括乳腺癌和卵巢癌在内的人类癌症中其表达上调或发生扩增。我们检测了多种肿瘤类型中的WIP1 mRNA水平，发现乳腺癌、白血病、髓母细胞瘤和神经母细胞瘤中的水平最高。神经母细胞瘤在诊断时是一种完全为TP53野生型的肿瘤，肿瘤发生需要p53的抑制。此前特别已表明，神经母细胞瘤存在17q扩增，含有WIP1（PPM1D）基因，且与不良临床预后相关。因此，我们试图确定用选择性拮抗剂GSK2830371抑制WIP1是否能通过重新激活p53介导的肿瘤抑制作用来减弱神经母细胞瘤细胞的生长。具有野生型TP53等位基因的神经母细胞瘤细胞系对GSK2830371治疗高度敏感，而具有突变型TP53的细胞系对GSK2830371耐药。大多数检测的PPM1D基因座拷贝数增加的神经母细胞瘤细胞系也是TP53野生型且对GSK2830371A敏感；相比之下，PPM1D无拷贝数增加的细胞系对WIP1抑制的敏感性不一，主要决定因素是TP53突变状态。由于WIP1参与细胞对DNA损伤的反应，且用于神经母细胞瘤治疗的药物通过DNA损伤诱导细胞凋亡，我们试图确定GSK2830371是否能与标准护理化疗药物协同作用。与单独使用任一药物相比，用GSK2830371和阿霉素或卡铂同时处理野生型TP53神经母细胞瘤细胞系会导致细胞死亡增加，这是通过诱导半胱天冬酶3/7介导的。我们的数据表明，抑制WIP1代表了一种可与当前化疗方法相结合的神经母细胞瘤新治疗方法。
