Combined inhibition of Notch and FLT3 produces synergistic cytotoxic effects in FLT3/ITD+ acute myeloid leukemia

Abstract

Internal tandem duplication (ITD) mutations of FMS-like tyrosine kinase-3 (FLT3) are the most frequent genetic alterations in acute myeloid leukemia (AML) and predict a poor prognosis. FLT3 tyrosine kinase inhibitors (TKIs) provide short-term clinical responses, but the long-term prognosis of FLT3/ITD + AML patients remains poor. Notch signaling is important in numerous types of tumors. However, the role of Notch signaling in FLT3/ITD + AML remains to be elucidated. In the current study, we found that Notch signaling was activated upon FLT3-TKI treatment in FLT3/ITD + cell lines and primary cells. As Notch signaling can be blocked by γ-secretase inhibitors (GSIs), we examined the combinatorial antitumor efficacy of FLT3-TKIs and GSIs against FLT3/ITD + AML and explored the underlying molecular mechanisms. As a result, we observed synergistic cytotoxic effects, and the treatment preferentially reduced cell proliferation and induced apoptosis in FLT3/ITD + AML cell lines and in primary AML cells. Furthermore, the combination of FLT3-TKI and GSI eradicated leukemic cells and prolonged survival in an FLT3/ITD + patient-derived xenograft AML model. Mechanistically, differential expression analysis suggested that CXCR3 may be partially responsible for the observed synergy, possibly through ERK signaling. Our findings suggest that combined therapies of FLT3-TKIs with GSI may be exploited as a potential therapeutic strategy to treat FLT3/ITD + AML.

CD44v6 chimeric antigen receptor T cell specificity towards AML with FLT3 or DNMT3A mutations

“…Therefore, CD44v6 expression was associated with FLT3 mutations or FLT3 overexpression which was also proved by our follow‐up experiments. Using the CRISPR/Cas9 system, we knocked in a 21‐bp ITD fragment in wild‐type SKM‐1 cells and named the knock‐in clone SKM‐1‐FLT3 21 . Compared to SKM‐1 cells, SKM‐1‐FLT3 cells significantly overexpressed FLT3 mRNA and CD44v6 (Figure 1A,B).…”

“…Using the CRISPR/Cas9 system, we knocked in a 21-bp ITD fragment in wild-type SKM-1 cells and named the knock-in clone SKM-1-FLT3. 21 Compared to SKM-1 cells, SKM-1-FLT3 cells significantly overexpressed FLT3 mRNA and CD44v6 (Figure 1A,B).…”

Proteomic profiling of plasma exosomes from patients with B-cell acute lymphoblastic leukemia

“…The Notch signaling pathway is a functional pathway that controls cell survival, proliferation, differentiation, apoptosis, migration, and invasion, and is involved in the determination of cell biological functions in both normal and pathological tissues 19 – 21 . Several studies have revealed the regulatory effect of the Notch signaling pathway in multiple cancers, including breast cancer 22 , colorectal cancer 23 , acute myeloid leukemia 24 , and ALL 25 . Indeed, Notch signaling pathway inhibitors, such as gamma-secretase inhibitors, have been considered as promising tools for cancer therapy 24 , 26 .…”

“…Several studies have revealed the regulatory effect of the Notch signaling pathway in multiple cancers, including breast cancer 22 , colorectal cancer 23 , acute myeloid leukemia 24 , and ALL 25 . Indeed, Notch signaling pathway inhibitors, such as gamma-secretase inhibitors, have been considered as promising tools for cancer therapy 24 , 26 . Additionally, Takam et al described a modulatory effect of the Notch pathway in B-ALL, with Notch pathway suppression leading to increased chemosensitivity of B-ALL cells 27 .…”

The Role of Notch, Hedgehog, and Wnt Signaling Pathways in the Resistance of Tumors to Anticancer Therapies

“…Mechanistically, Notch signaling was upregulated following treatment with FLT3-TKIs, which resulted in alternative ERK activation. The addition of Notch inhibitor (GSI) abrogated the alternative activation of ERK, resulting in extreme repression of ERK activity, thereby showing a synergistic antitumor effect ( Li D. et al, 2020 ). Likewise, lung adenocarcinoma patients with activating EGFR L858R mutation show a better response to TKIs initially but subsequently develop resistance and show increased HES1 protein levels that correlate with shorter progression-free survival ( Bousquet Mur et al, 2020 ).…”