DataSheet1_HSP90 Inhibitor Ganetespib Enhances the Sensitivity of Mantle Cell Lymphoma to Bruton’s Tyrosine Kinase Inhibitor Ibrutinib.DOCX

Mantle cell lymphoma (MCL) is a highly aggressive and heterogeneous B-cell lymphoma. Though Bruton’s tyrosine kinase (BTK) inhibitor ibrutinib has shown great efficacy as a single agent for MCL treatment, the real-world use of ibrutinib is still subject to limitations. Our previous study has shown the treatment with HSP90 inhibitor ganetespib can attack major targets of MCL, luckily complementary to ibrutinib’s targets. In this study, transient ganetespib treatment sensitizes MCL cells to ibrutinib as manifested by the significant decrease of IC50 values, percentages of EdU (5-Ethynyl-2′-deoxyuridine) positive cells, and levels of p-AKT and NF-κB after combinational treatment. Additionally, pretreatment with ganetespib enhanced cell cycle arrest induced by ibrutinib at G0/G1 phase and significantly decreased levels of cell cycle promoting proteins CDK2, 4, and 6. Pretreatment with ganetespib also enhanced cell apoptosis induced by ibrutinib through the upregulation of cleaved-caspase 9 and downregulation of BCL-2 in MCL cells at the molecular level. The sequential administration of ganetespib and ibrutinib had similar effects on increasing DNA damage as the transient treatment with ganetespib as demonstrated by the improved percentage of γH2AX and 53BP1 foci. Furthermore, ganetespib significantly increased inhibition of tumor growth mediated by ibrutinib in vivo, confirmed by the changes of the expression levels of Ki-67 and BCL-2 through immunohistochemistry assays. This study indicates that HSP90 inhibitor ganetespib maybe ideal for the combinational use with BTK inhibitor ibrutinib to target major pathogenesis-associated signaling pathways for MCL treatment which may help identify new possibilities for clinical trials.

套细胞淋巴瘤（Mantle cell lymphoma，MCL）是一种高度侵袭性和异质性的B细胞淋巴瘤。尽管布鲁顿酪氨酸激酶（Bruton’s tyrosine kinase，BTK）抑制剂伊布替尼在MCL单一药物治疗中已显示出显著的疗效，但伊布替尼在现实世界的应用仍存在局限性。我们的前期研究表明，使用HSP90抑制剂甘尼替宾（ganetespib）的治疗可以针对MCL的主要靶点，幸运的是，这与伊布替尼的靶点相辅相成。在本研究中，短暂的甘尼替宾治疗通过联合治疗显著降低了IC50值、EdU（5-乙炔-2′-脱氧尿苷）阳性细胞百分比以及p-AKT和NF-κB的水平，从而使得MCL细胞对伊布替尼的敏感性增强。此外，甘尼替宾的预处理增强了伊布替尼诱导的G0/G1期细胞周期阻滞，并显著降低了细胞周期促进蛋白CDK2、4和6的水平。甘尼替宾的预处理还通过在MCL细胞分子水平上上调裂解的caspase 9和下调BCL-2，增强了伊布替尼诱导的细胞凋亡。甘尼替宾与伊布替尼的序贯给药在增加DNA损伤方面具有与甘尼替宾短暂治疗相似的效果，如γH2AX和53BP1焦点的百分比所证实的。此外，甘尼替宾显著增加了伊布替尼介导的体内肿瘤生长抑制，这通过免疫组化检测中Ki-67和BCL-2表达水平的变化得到证实。本研究表明，HSP90抑制剂甘尼替宾可能非常适合与BTK抑制剂伊布替尼联合使用，以针对MCL的主要发病机制相关信号通路进行治疗，这可能有助于识别临床试验的新可能性。