Global Regulation of Differential Gene Expression by c-Abl/Arg Oncogenic Kinases

The tyrosine kinase c-Abl potentiates interferon-mediated antiviral immunity by STAT1 phosphorylation

Interferon (IFN)-induced activation of the signal transducer and activator of transcription (STAT) family is an important event in antiviral immunity. Here, we show that the nonreceptor kinases c-Abl and Arg directly interact with STAT1 and potentiate the phosphorylation of STAT1 on Y701. c-Abl/Arg could mediate STAT1 phosphorylation independent of Janus kinases in the absence of IFNγ and potentiate IFNγ-mediated STAT1 phosphorylation. Moreover, STAT1 dimerization, nuclear translocation, and downstream gene transcription are regulated by c-Abl/Arg. c-Abl/Arg (abl1/abl2) deficiency significantly suppresses antiviral responses in vesicular stomatitis virus-infected cells. Compared to vehicle, administration of the c-Abl/Arg selective inhibitor AMN107 resulted in significantly increased mortality in mice infected with human influenza virus. Our study demonstrates that c-Abl plays an essential role in the STAT1 activation signaling pathway and provides an important approach for antiviral immunity regulation.

Nonreceptor Tyrosine Kinase c-Abl- and Arg-Mediated IRF3 Phosphorylation Regulates Innate Immune Responses by Promoting Type I IFN Production

The nonreceptor tyrosine kinase c-Abl plays important roles in T cell development and immune responses; however, the mechanism is poorly understood. IFN regulatory factor 3 (IRF3) is a key transcriptional regulator of type I IFN-dependent immune responses against DNA and RNA viruses. The data in this study show that IRF3 is physically associated with c-Abl in vivo and directly binds to c-Abl in vitro. IRF3 is phosphorylated by c-Abl and c-Abl-related kinase, Arg, mainly at Y292. The inhibitor AMN107 inhibits IFN-β production induced by poly(dA:dT), poly(I:C), and Sendai virus in THP-1 and mouse bone marrow-derived macrophage cells. IRF3-induced transcription of IFN-β is significantly reduced by the mutation of Y292 to F. Moreover, AMN107 suppresses gene expression of absent in melanoma 2 (AIM2) and subsequently reduces inflammasome activation induced by cytosolic bacteria, dsDNA, and DNA viruses. Consistent with this finding, Francisella tularensis subsp. holarctica live vaccine strain (Ft LVS), which is known as an activator of AIM2 inflammasome, induces death in significantly more C57BL/6 mice treated with the Abl inhibitor AMN107 or c-Abl/Arg small interfering RNA than in untreated mice. This study provides new insight into the function of c-Abl and Arg in regulating immune responses and AIM2 inflammasome activation, especially against Ft LVS infection.

EnABLing Tumor Growth and Progression: Recent progress in unraveling the functions of ABL kinases in solid tumor cells

PURPOSE OF REVIEW

The goal of this review is to summarize our current knowledge regarding how ABL family kinases are activated in solid tumors and impact on solid tumor development/progression, with a focus on recent advances in the field.

RECENT FINDINGS

Although ABL kinases are known drivers of human leukemia, emerging data also implicates the kinases in a large number of solid tumor types where they promote diverse processes such as proliferation, survival, cytoskeletal reorganization, cellular polarity, EMT (epithelial-mesenchymal-transition), metabolic reprogramming, migration, invasion and metastasis via unique signaling pathways. ABL1 and ABL2 appear to have overlapping but also unique roles in driving these processes. In some tumor types, the kinases may act to integrate pro- and anti-proliferative and -invasive signals, and also may serve as a switch during EMT/MET (mesenchymal-epithelial) transitions.

CONCLUSIONS

Most data indicate that targeting ABL kinases may be effective for reducing tumor growth and preventing metastasis; however, ABL kinases also may have a tumor suppressive role in some tumor types and in some cellular contexts. Understanding the functions of ABL kinases in solid tumors is critical for developing successful clinical trials aimed at targeting ABL kinases for the treatment of solid tumors.