Claudiani Simone, Mason Clinton C, Milojkovic Dragana, Bianchi Andrea, Pellegrini Cristina, Di Marco Antinisca, Fiol Carme R, Robinson Mark, Ponnusamy Kanagaraju, Mokretar Katya, Chowdhury Avirup, Albert Michael, Reid Alistair G, Deininger Michael W, Naresh Kikkeri, Apperley Jane F, Khorashad Jamshid S
Centre for Haematology, Department of Immunology and Inflammation, Imperial College, London W12 0NN, UK.
Department of Pediatrics, Division of Pediatric Hematology and Oncology, University of Utah, Salt Lake City, UT 84108, USA.
Cancers (Basel). 2021 Sep 28;13(19):4863. doi: 10.3390/cancers13194863.
As the first FDA-approved tyrosine kinase inhibitor for treatment of patients with myelofibrosis (MF), ruxolitinib improves clinical symptoms but does not lead to eradication of the disease or significant reduction of the mutated allele burden. The resistance of MF clones against the suppressive action of ruxolitinib may be due to intrinsic or extrinsic mechanisms leading to activity of additional pro-survival genes or signalling pathways that function independently of JAK2/STAT5. To identify alternative therapeutic targets, we applied a pooled-shRNA library targeting ~5000 genes to a -positive cell line under a variety of conditions, including absence or presence of ruxolitinib and in the presence of a bone marrow microenvironment-like culture medium. We identified several proteasomal gene family members as essential to HEL cell survival. The importance of these genes was validated in MF cells using the proteasomal inhibitor carfilzomib, which also enhanced lethality in combination with ruxolitinib. We also showed that proteasome gene expression is reduced by ruxolitinib in MF CD34 cells and that additional targeting of proteasomal activity by carfilzomib enhances the inhibitory action of ruxolitinib in vitro. Hence, this study suggests a potential role for proteasome inhibitors in combination with ruxolitinib for management of MF patients.
作为美国食品药品监督管理局（FDA）批准的首个用于治疗骨髓纤维化（MF）患者的酪氨酸激酶抑制剂，芦可替尼可改善临床症状，但无法根除疾病或显著降低突变等位基因负担。MF克隆对芦可替尼抑制作用的耐药性可能归因于内在或外在机制，这些机制导致其他促生存基因或信号通路激活，这些基因或通路独立于JAK2/STAT5发挥作用。为了确定替代治疗靶点，我们在多种条件下，包括在不存在或存在芦可替尼的情况下以及在存在骨髓微环境样培养基的情况下，将靶向约5000个基因的混合短发夹RNA（shRNA）文库应用于一个阳性细胞系。我们确定了几个蛋白酶体基因家族成员对HEL细胞存活至关重要。使用蛋白酶体抑制剂卡非佐米在MF细胞中验证了这些基因的重要性，卡非佐米与芦可替尼联合使用时也增强了杀伤力。我们还表明，芦可替尼可降低MF CD34细胞中的蛋白酶体基因表达，并且卡非佐米对蛋白酶体活性的额外靶向作用可增强芦可替尼在体外的抑制作用。因此，本研究表明蛋白酶体抑制剂与芦可替尼联合使用在MF患者管理中具有潜在作用。
