Glucocorticoid resistance is reverted by LCK inhibition in pediatric T-cell acute lymphoblastic leukemia

Abstract

Pediatric T-acute lymphoblastic leukemia (T-ALL) patients often display resistance to glucocorticoid (GC) treatment. These patients, classified as prednisone poor responders (PPR), have poorer outcome than do the other pediatric T-ALL patients receiving a high-risk adapted therapy. Because glucocorticoids are administered to ALL patients during all the different phases of therapy, GC resistance represents an important challenge to improving the outcome for these patients. Mechanisms underlying resistance are not yet fully unraveled; thus our research focused on the identification of deregulated signaling pathways to point out new targeted approaches. We first identified, by reverse-phase protein arrays, the lymphocyte cell-specific protein-tyrosine kinase (LCK) as aberrantly activated in PPR patients. We showed that LCK inhibitors, such as dasatinib, bosutinib, nintedanib, and WH-4-023, are able to induce cell death in GC-resistant T-ALL cells, and remarkably, cotreatment with dexamethasone is able to reverse GC resistance, even at therapeutic drug concentrations. This was confirmed by specific gene silencing and ex vivo combined treatment of cells from PPR patient-derived xenografts. Moreover, we observed that LCK hyperactivation in PPR patients upregulates the calcineurin/nuclear factor of activated T cells signaling triggering to interleukin-4 () overexpression. GC-sensitive cells cultured with IL-4 display an increased resistance to dexamethasone, whereas the inhibition of IL-4 signaling could increase GC-induced apoptosis in resistant cells. Treatment with dexamethasone and dasatinib also impaired engraftment of leukemia cells in vivo. Our results suggest a quickly actionable approach to supporting conventional therapies and overcoming GC resistance in pediatric T-ALL patients.

Tamoxifen induces toxicity, causes autophagy, and partially reverses dexamethasone resistance in Jurkat T cells

“…The crucial role of autophagy in DEX‐induced cell death was confirmed by the fact that autophagy inhibition precluded apoptosis in these cells. Because GC are administered to leukemic patients during all phases of therapy, GC resistance represents an essential challenge to improve the outcome of these patients . At the same time, the referenced work represents the only study relating GC resistance with the autophagic process.…”

“…Because GC are administered to leukemic patients during all phases of therapy, GC resistance represents an essential challenge to improve the outcome of these patients. 32 At the same time, the referenced work represents the only study relating GC resistance with the autophagic process. Since there is no previously published evidence on the biological effects of TAMinduced autophagy in T-ALL, the present work was designed to study the antileukemic effect of TAM, its capability to induce autophagy and reverse GC-resistance in the Jurkat cell line derived from a T-ALL sample in relapse.…”

SYK Targeting Represents a Potential Therapeutic Option for Relapsed Resistant Pediatric ETV6-RUNX1 B-Acute Lymphoblastic Leukemia Patients

“…These results prompted us to evaluate the levels of expression and phosphorylation of SYK in a cohort of 64 pediatric ETV6-RUNX1 patients at diagnosis. By using reverse-phase protein arrays (RPPA) [10], we compared SYK expression and activation between relapsed (n = 11) and nonrelapsed (n = 53) patients through an unpaired t test with Welch's correction. From this analysis we identified the hyperactivation of SYK, phosphorylated in Y525, at diagnosis in patients who will experience relapse (p = 0.02) (Figure 2a).…”

“…Cell viability of cell lines treated with entospletinib, fostamatinib and PRT-060318 alone or in combination with chemotherapeutic drugs was assessed by MTT ((3-(4,5dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay as previously described [10].…”

Epigenetic Landscape in Leukemia and Its Impact on Antileukemia Therapeutics

“…Mutations in epigenetic regulators such as KMT2D, CREBBP, and HDAC7, in two of five resistant PDX models, could not account for abnormal epigenetic changes. Mutations in various signaling pathways [73][74][75][76] have been reported to impair glucocorticoid-induced apoptosis in ALL by downregulating the GR-activated pro-apoptotic gene, BIM expression. The importance to study beyond gene mutations, toward epigenetic mapping of GR binding, will provide a deeper understanding into individual drug response.…”