AEW-541

To explore whether Ph⁺ acute lymphoblastic leukemia (ALL) cell line SUP-B15 treated with imatinib occurs a tolerant status charactered by cell proliferation suppression but apoptotic resistance, then evaluate whether IGF1-R inhibitor AEW541 can break this tolerance, and further explain its mechanisms.

SUP-B15 cells were treated with different concentrations of imatinib or AEW541. Cell proliferation was assayed by Deep Blue, and apoptotic cells were determined by Annexin V/7-AAD staining. Apoptotic rate was measured by flow cytometry after co-treatment of imatinib and AEW541. Western blot was used to evaluate ABL downstream signals, including the phosphorylation of STAT5, ERK1/2, and AKT, as well as to detect cleaved caspase-3 and PARP1, the molecular signatures of apoptosis. Furthermore, an inhibitor of STAT5 or MEK-ERK1/2 was used to confirm the key mechanism of the combination of imatinib and AEW541 induced SUP-B15 cell apoptosis.

Imatinib monotherapy effectively suppressed the proliferation of SUP-B15 cells, but did not induce significant increase of apoptotic rate, leading to occurrence of tolerant status. AEW541 monotherapy did not dramatically affect the proliferation and apoptosis of SUP-B15 cells, but significantly increased apoptotic rate of SUP-B15 cells and cleavage of caspase-3 and PARP1 when combined with imatinib simultaneously. A combination of imatinib and AEW541 reduced STAT5 and ERK1/2 phosphorylation as compared with imatinib monotherapy in SUP-B15 cells, but had no impact on AKT phosphorylation.Apoptosis could be induced by STAT5 inhibitor AC-4-130, but not by MEK-ERK1/2 inhibitor trametinib in SUP-B15 cells.

SUP-B15 cells treated with imatinib can establish drug tolerance. IGF1-R inhibitor AEW541 can further reduce STAT5 activation, thereby boosting the effect of apoptotic induction of imatinib on SUP-B15 cells. This research may provide a new idear to overcome imatinib tolerance.

Myocardial infarction (MI)-induced heart failure (HF) is commonly accompanied with profound effects on skeletal muscle. With the process of MI-induced HF, perturbations in skeletal muscle contribute to muscle atrophy. Exercise is viewed as a feasible strategy to prevent muscle atrophy. The aims of this study were to investigate whether exercise could alleviate MI-induced skeletal muscle atrophy via insulin-like growth factor 1 (IGF-1) pathway in mice. Male C57/BL6 mice were used to establish the MI model and were divided into three groups: sedentary MI group (MI), MI with aerobic exercise group, and MI with resistance exercise group; sham-operated group was used as control. Exercise-trained animals were subjected to 4 wk of aerobic exercise (AE) or resistance exercise (RE). Cardiac function, muscle weight, myofiber size, levels of IGF-1 signaling and proteins related to myogenesis, protein synthesis, and degradation and apoptosis in gastrocnemius muscle were detected. H2O2-treated C2C12 cells were intervened with recombinant human IGF-1, IGF-1 receptor (IGF-1R) inhibitor NVP-AEW541, and PI3K inhibitor LY294002 to explore the mechanism. Exercises upregulated the IGF-1/IGF-1R-phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling; increased the expressions of Pax7, myogenic regulatory factors (MRFs), and protein synthesis; and reduced protein degradation and cell apoptosis in MI mice. In vitro, IGF-1 upregulated the levels of Pax7, MRFs, mTOR, and P70S6K; reduced MuRF1 and MAFbx; and inhibited cell apoptosis via IGF-1R-PI3K/Akt pathway. AE and RE, safely and effectively, alleviate skeletal muscle atrophy by regulating the levels of myogenesis, protein degradation, and cell apoptosis in mice with MI via activating IGF-1/IGF-1R-PI3K/Akt signaling pathway.