Cardiac fibrosis is a significant global health problem with limited treatment choices. Although previous studies have shown that imatinib (IMA) inhibited cardiac fibrosis, the anti-fibrotic mechanisms have not been clearly uncovered. The aim of this study is to evaluate whether IMA attenuates cardiac fibrosis by inhibiting platelet-derived growth factor receptors (PDGFR) on isoproterenol (ISO)-induced mice. Adult male C57BL/6 mice were treated with vehicle or ISO ± IMA for one week. After echocardiography examination, the hearts of mice were used for histopathologic, RT-qPCR, and western blot analyses. We found that the ventricular wall thickness, cardiac hypertrophy, and apoptosis were enhanced following ISO treatment. IMA decreased the left ventricular wall thickness, prevented hypertrophy, and inhibited apoptosis induced by ISO. In addition, IMA attenuated the accumulation of collagens and α-smooth muscle actin (α-SMA) (the markers of fibrosis) caused by ISO treatment. Moreover, the expression of fibrosis related genes, and the phosphorylation of PDGFRs in ISO-treated mice hearts were inhibited by IMA as well. However, IMA did not change the expression of the matrix metalloproteinase-9 (MMP-9) in ISO-treated hearts. Furthermore, IMA reduced the expressions of collagens as well as α-SMA caused by activation of PDGFRα in cardiac fibroblasts. Taken together, our data demonstrate that IMA attenuated the cardiac fibrosis by blocking the phosphorylation of PDGFRs in the ISO-induced mice model. This study indicates that IMA could be a potentially therapeutic option for cardiac fibrosis in clinical application.

Acute myeloid leukemia (AML) mesenchymal stem cells (MSCs) play an essential role in protecting leukemic cells from chemotherapeutic agents through activating a wide range of adhesion molecules and cytokines. Thus, more attention should be paid to attenuate the protection of leukemic cells by MSCs. By examining the gene expression files of MSCs from healthy donors and AML patients through high-throughput microarrays, we found that interleukin (IL)-6 was an important cytokine secreted by AML MSCs to protect leukemic cells, contributing to disease progression. Strikingly, Aurora A (AURKA) was activated by IL-6, offering a new target to interfere with leukemia. Importantly, a novel AURKA inhibitor, PW21, showed excellent AURKA kinase inhibitory activities and attenuated the interaction of leukemic cells and the microenvironment. PW21 inhibited MSC-induced cell proliferation, colony formation, and migration, and it induced cell apoptosis. Mechanically, PW21 could inhibit IL-6 secreted by MSCs. Moreover, we found that PW21 displayed a strong anti-leukemia effect on non-obese diabetic (NOD)-severe combined immunodeficiency (SCID) and murine MLL-AF9 leukemic models. PW21 significantly prolonged the survival of leukemic mice and eliminated the leukemic progenitor cells. AURKA inhibitor PW21 could provide a new approach for treatment of leukemia through blocking the protection by the leukemic microenvironment in clinical application.