Abstract
Background Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy. Despite recent therapeutic advances, patients continue to experience poor outcomes and high rates of relapse, highlighting the need for novel targeted therapies,particularly for patients with primary resistance and relapse. Selinexor, a selective inhibitor of nuclear export (SINE), targets exportin-1 (XPO1) and impedes nuclear-cytoplasmic trafficking, leading to nuclear accumulation of tumor suppressors, cell cycle regulators, and DNA damage response proteins(Cancer discovery 2014 May; 4(5): 527-537). Preclinical studies have demonstrated that selinexor induces cell cycle arrest and apoptosis in AML cell lines(Blood 2012 Aug 30; 120(9): 1765-1773). Selinexor—either as monotherapy or in combination with chemotherapy—has shown efficacy and acceptable tolerability in patients with relapsed or refractory AML(Haematologica 2018 Oct; 103(10): 1642-1653). However, the variability in patient responses highlights the urgent need for predictive biomarkers of selinexor sensitivity.
LNK, encoded by SH2B3, is a member of the SH2B adaptor family, comprising conserved dimerization, pleckstrin homology, and SH2 domains(Archivum immunologiae et therapiae experimentalis 2012 Dec; 60(6): 415-429). It modulates signaling downstream of various cytokines and growth factor receptors(Journal of immunology (Baltimore, Md : 1950) 2000 May 15; 164(10): 5199-5206). LNK is highly expressed in hematopoietic stem cells, and negatively regulates thrombopoietin and erythropoietin signaling via JAK2 binding(Circulation research 2009 Apr 24; 104(8): 969-977). Here, we investigate whether SH2B3 expression levels predict selinexor sensitivity in AML, with the aim of improving patient stratification and therapeutic outcomes.
Methods First, the sensitivity of eight human AML cell lines (MV4-11, OCI-AML3, MOLM-13, K562, THP-1, U937, HL-60, and SKM-1) to selinexor was assessed. Cell viability following selinexor treatment was measured using CCK-8 assays, and apoptosis was quantified by annexin V/propidium iodide staining with flow cytometry. Baseline transcriptomic data of AML cell lines were retrieved from the Cell Model Passports database. Differential gene expression analysis between selinexor-sensitive and -resistant AML cells was performed in R using the limma package (thresholds: adjusted P < 0.05, |log₂ fold-change| > 1). SH2B3 knockdown and overexpression were achieved via lentiviral transduction using pLKO.1 and pCDH vectors, respectively; transduction efficiency was verified by qRT-PCR and Western blot.
Results AML cell lines segregated into high-sensitivity (MV4-11, OCI-AML3, MOLM-13, K562) and low-sensitivity (THP-1, U937, HL-60, SKM-1) groups based on half-maximal inhibitory concentration (IC₅₀) values and apoptosis response to selinexor. Comparison of transcriptome sequencing data identified SH2B3 as the most significantly differentially expressed gene between these groups. Functional modulation of SH2B3 altered selinexor response: SH2B3 knockdown in high-sensitivity AML cells attenuated drug efficacy, whereas SH2B3 overexpression in resistant AML cells enhanced proliferation inhibition and apoptotic induction of selinexor. These findings indicate that SH2B3 expression levels directly influence selinexor sensitivity in AML cells.
Conclusion Our data demonstrate that SH2B3 expression correlates with selinexor responsiveness in AML cell lines. Modulation of SH2B3 influence selinexor-induced cell growth and apoptosis, suggesting its potential utility as a predictive biomarker. Given that the LNK protein interacts with JAK2 and inhibits JAK-STAT signaling(Jiang J,et al 2012; Baran-Marszak F,et al 2010; Bersenev A, et al 2010; Gery S, et al2009), we hypothesize that SH2B3's impact on selinexor sensitivity may be mediated through this pathway. Ongoing studies are investigating the mechanistic interplay between SH2B3, JAK-STAT signaling, and XPO1 inhibition, to further refine biomarker-guided therapeutic strategies in AML.
