NSC114792, a novel small molecule identified through structure-based computational database screening, selectively inhibits JAK3

The oncogenic mechanisms of the Janus kinase-signal transducer and activator of transcription pathway in digestive tract tumors

Digestive tract tumors are heterogeneous and involve the dysregulation of multiple signaling pathways. The Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway plays a notable role in the oncogenesis of digestive tract tumors. Typically activated by pro-inflammatory cytokines, it regulates important biological processes, such as cell growth, differentiation, apoptosis, immune responses, and inflammation. The aberrant activation of this pathway manifests in different forms, including mutations in JAKs, overexpression of cytokine receptors, and sustained STAT activation, and contributes to promoting the malignant characteristics of cancer cells, including uncontrolled proliferation, resistance to apoptosis, enhanced invasion and metastasis, angiogenesis, acquisition of stem-like properties, and drug resistance. Numerous studies have shown that aberrant activation of the JAK-STAT pathway is closely related to the development and progression of digestive tract tumors, contributing to tumor survival, angiogenesis, changes in the tumor microenvironment, and even immune escape processes. In addition, this signaling pathway also affects the sensitivity of digestive tract tumors to chemotherapy and targeted therapy. Therefore, it is crucial to comprehensively understand the oncogenic mechanisms underlying the JAK-STAT pathway in order to develop effective therapeutic strategies against digestive tract tumors. Currently, several JAK-STAT inhibitors are undergoing clinical and preclinical trials as potential treatments for various human diseases. However, further investigation is required to determine the role of this pathway, as well as the effectiveness and safety of its inhibitors, especially in the context of digestive tract tumors. In this review, we provide an overview of the structure, classic activation, and negative regulation of the JAK-STAT pathway. Furthermore, we discuss the pathogenic mechanisms of JAK-STAT signaling in different digestive tract tumors, with the aim of identifying potential novel therapeutic targets. Video Abstract.

STAT3 Inhibitor ODZ10117 Suppresses Glioblastoma Malignancy and Prolongs Survival in a Glioblastoma Xenograft Model

Constitutively activated STAT3 plays an essential role in the initiation, progression, maintenance, malignancy, and drug resistance of cancer, including glioblastoma, suggesting that STAT3 is a potential therapeutic target for cancer therapy. We recently identified ODZ10117 as a small molecule inhibitor of STAT3 and suggested that it may have an effective therapeutic utility for the STAT3-targeted cancer therapy. Here, we demonstrated the therapeutic efficacy of ODZ10117 in glioblastoma by targeting STAT3. ODZ10117 inhibited migration and invasion and induced apoptotic cell death by targeting STAT3 in glioblastoma cells and patient-derived primary glioblastoma cells. In addition, ODZ10117 suppressed stem cell properties in glioma stem cells (GSCs). Finally, the administration of ODZ10117 showed significant therapeutic efficacy in mouse xenograft models of GSCs and glioblastoma cells. Collectively, ODZ10117 is a promising therapeutic candidate for glioblastoma by targeting STAT3.

Evolution of In Silico Strategies for Protein-Protein Interaction Drug Discovery

The advent of advanced molecular modeling software, big data analytics, and high-speed processing units has led to the exponential evolution of modern drug discovery and better insights into complex biological processes and disease networks. This has progressively steered current research interests to understanding protein-protein interaction (PPI) systems that are related to a number of relevant diseases, such as cancer, neurological illnesses, metabolic disorders, etc. However, targeting PPIs are challenging due to their "undruggable" binding interfaces. In this review, we focus on the current obstacles that impede PPI drug discovery, and how recent discoveries and advances in in silico approaches can alleviate these barriers to expedite the search for potential leads, as shown in several exemplary studies. We will also discuss about currently available information on PPI compounds and systems, along with their usefulness in molecular modeling. Finally, we conclude by presenting the limits of in silico application in drug discovery and offer a perspective in the field of computer-aided PPI drug discovery.

JAK1-dependent transphosphorylation of JAK2 limits the antifibrotic effects of selective JAK2 inhibitors on long-term treatment

Objectives

Janus kinase 2 (JAK2) has recently been described as a novel downstream mediator of the pro-fibrotic effects of transforming growth factor-β. Although JAK2 inhibitors are in clinical use for myelodysplastic syndromes, patients often rapidly develop resistance. Tumour cells can escape the therapeutic effects of selective JAK2 inhibitors by mutation-independent transactivation of JAK2 by JAK1. Here, we used selective JAK2 inhibition as a model to test the hypothesis that chronic treatment may provoke resistance by facilitating non-physiological signalling pathways in fibroblasts.

Methods

The antifibrotic effects of long-term treatment with selective JAK2 inhibitors and reactivation of JAK2 signalling by JAK1-dependent transphosphorylation was analysed in cultured fibroblasts and experimental dermal and pulmonary fibrosis. Combined JAK1/JAK2 inhibition and co-treatment with an HSP90 inhibitor were evaluated as strategies to overcome resistance.

Results

The antifibrotic effects of selective JAK2 inhibitors on fibroblasts decreased with prolonged treatment as JAK2 signalling was reactivated by JAK1-dependent transphosphorylation of JAK2. This reactivation could be prevented by HSP90 inhibition, which destabilised JAK2 protein, or with combined JAK1/JAK2 inhibitors. Treatment with combined JAK1/JAK2 inhibitors or with JAK2 inhibitors in combination with HSP90 inhibitors was more effective than monotherapy with JAK2 inhibitors in bleomycin-induced pulmonary fibrosis and in adTBR-induced dermal fibrosis.

Conclusion

Fibroblasts can develop resistance to chronic treatment with JAK2 inhibitors by induction of non-physiological JAK1-dependent transactivation of JAK2 and that inhibition of this compensatory signalling pathway, for example, by co-inhibition of JAK1 or HSP90 is important to maintain the antifibrotic effects of JAK2 inhibition with long-term treatment.

The Use of JAK-specific inhibitors as chemical biology tools

The JAK family of protein tyrosine kinases are now recognized as important participants in a wide range of pathologies, from cancer to inflammatory diseases. In the last decade, the drive to develop drugs targeting members of this family has begun to deliver a panel of small molecule inhibitors of JAK family members, with a range of potencies and specificities. A number of these compounds have already found widespread use as biochemical tools in the elucidation of JAK activity in specific signaling and disease processes; however, many of the first generation compounds are poorly characterized with suboptimal potencies and selectivities.Herein, we present the data for those small molecule JAK inhibitors that have been described in the peer-reviewed literature and the benefits and potential issues that may be associated with the use of these tool compounds.

Spirooxindole derivative SOID-8 induces apoptosis associated with inhibition of JAK2/STAT3 signaling in melanoma cells

Melanoma is generally refractory to current chemotherapy, thus new treatment strategies are needed. In this study, we synthesized a series of spirooxindole derivatives (SOID-1 to SOID-12) and evaluated their antitumor effects on melanoma. Among the 12 spirooxindole derivatives, SOID-8 showed the strongest antitumor activity by viability screening. SOID-8 inhibited viability of A2058, A375, SK-MEL-5 and SK-MEL-28 human melanoma cells in a dose- and time-dependent manner. SOID-8 also induced apoptosis of these tumor cells, which was confirmed by positive Annexin V staining and an increase of poly(ADP-ribose) polymerase cleavage. The antiapoptotic protein Mcl-1, a member of the Bcl-2 family, was downregulated and correlated with SOID-8 induced apoptosis. In addition, SOID-8 reduced tyrosine phosphorylation of Signal Tansducer and Activator of Transcription 3 (STAT3) in both dose- and time-dependent manners. This inhibition was associated with decreased levels of phosphorylation of Janus-activated kinase-2 (JAK2), an upstream kinase that mediates STAT3 phosphorylation at Tyr705. Accordingly, SOID-8 inhibited IL-6-induced activation of STAT3 and JAK2 in melanoma cells. Finally, SOID-8 suppressed melanoma tumor growth in a mouse xenograft model, accompanied with a decrease of phosphorylation of JAK2 and STAT3. Our results indicate that the antitumor activity of SOID-8 is at least partially due to inhibition of JAK2/STAT3 signaling in melanoma cells. These findings suggest that the spirooxindole derivative SOID-8 is a promising lead compound for further development of new preventive and therapeutic agents for melanoma.

Acute leukemias in children with Down syndrome

Children with Down syndrome (DS) often present with hematopoietic abnormalities, and are at increased risk of developing leukemia. Specifically, 3-10% of newborns with DS are diagnosed with transient myeloproliferative disease, and children with DS are 500 times more likely to develop acute megakaryoblastic leukemia (AMKL) and 20 times more likely to develop acute lymphoblastic leukemia (ALL) than typical children. This review examines the characteristics of these leukemias and their development in the unique genetic background of trisomy 21. A discussion is also provided for areas of future research and potential therapeutic development.

First-in-class small molecule inhibitors of the single-strand DNA cytosine deaminase APOBEC3G

APOBEC3G is a single-stranded DNA cytosine deaminase that comprises part of the innate immune response to viruses and transposons. Although APOBEC3G is the prototype for understanding the larger mammalian polynucleotide deaminase family, no specific chemical inhibitors exist to modulate its activity. High-throughput screening identified 34 compounds that inhibit APOBEC3G catalytic activity. Twenty of 34 small molecules contained catechol moieties, which are known to be sulfhydryl reactive following oxidation to the orthoquinone. Located proximal to the active site, C321 was identified as the binding site for the inhibitors by a combination of mutational screening, structural analysis, and mass spectrometry. Bulkier substitutions C321-to-L, F, Y, or W mimicked chemical inhibition. A strong specificity for APOBEC3G was evident, as most compounds failed to inhibit the related APOBEC3A enzyme or the unrelated enzymes E. coli uracil DNA glycosylase, HIV-1 RNase H, or HIV-1 integrase. Partial, but not complete, sensitivity could be conferred to APOBEC3A by introducing the entire C321 loop from APOBEC3G. Thus, a structural model is presented in which the mechanism of inhibition is both specific and competitive, by binding a pocket adjacent to the APOBEC3G active site, reacting with C321, and blocking access to substrate DNA cytosines.

Kinase inhibitors in the treatment of immune-mediated disease

Protein kinases are fundamental components of diverse signaling pathways, including immune cells. Their essential functions have made them effective therapeutic targets. Initially, the expectation was that a high degree of selectivity would be critical; however, with time, the use of "multikinase" inhibitors has expanded. Moreover, the spectrum of diseases in which kinase inhibitors are used has also expanded to include not only malignancies but also immune-mediated diseases. At present, thirteen kinase inhibitors have been approved in the United States, all for oncologic indications. However, there are a growing number of molecules, including several Janus kinase inhibitors, that are being tested in clinical trials for autoimmune diseases such as rheumatoid arthritis, psoriasis and inflammatory bowel diseases. It appears likely that this new class of immunomodulatory drugs will have a major impact on the treatment of immune-mediated diseases in the near future.

Inhibition of the signalling kinase JAK3 alleviates inflammation in monoarthritic rats

BACKGROUND AND PURPOSE

Many cytokines associated with autoimmune disorders and inflammation have been shown to activate the signalling kinase JAK3, implying that JAK3 plays key roles in the pathogenesis of these diseases. Therefore, investigating the alterations of JAK3 activity and the efficacy of selective JAK3 antagonists in animal models of such disorders is essential to a better understanding of the biology of JAK3 and to assess the potential clinical benefits of JAK3 inhibitors.

EXPERIMENTAL APPROACH

Through high-throughput cell-based screening using the NCI compound library, we identified NSC163088 (berberine chloride) as a novel inhibitor of JAK3. Specificity and efficacy of this compound were investigated in both cellular and animal models.

KEY RESULTS

We show that berberine chloride has selectivity for JAK3 over other JAK kinase members, as well as over other oncogenic kinases such as Src, in various cellular assays. Biochemical and modelling studies strongly suggested that berberine chloride bound directly to the kinase domain of JAK3. Also phospho-JAK3 levels were significantly increased in the synovial tissues of rat joints with acute inflammation, and the treatment of these rats with berberine chloride decreased JAK3 phosphorylation and suppressed the inflammatory responses.

CONCLUSIONS AND IMPLICATIONS

The up-regulation of JAK3/STATs was closely correlated with acute arthritic inflammation and that inhibition of JAK3 activity by JAK3 antagonists, such as berberine chloride, alleviated the inflammation in vivo.

Benzoxathiol derivative BOT-4-one suppresses L540 lymphoma cell survival and proliferation via inhibition of JAK3/STAT3 signaling

Persistently activated JAK/STAT3 signaling pathway plays a pivotal role in various human cancers including major carcinomas and hematologic tumors, and is implicated in cancer cell survival and proliferation. Therefore, inhibition of JAK/STAT3 signaling may be a clinical application in cancer therapy. Here, we report that 2-cyclohexylimino-6-methyl-6,7-dihydro-5H-benzo [1,3]oxathiol-4-one (BOT-4-one), a small molecule inhibitor of JAK/STAT3 signaling, induces apoptosis through inhibition of STAT3 activation. BOT-4-one suppressed cytokine (upd)-induced tyrosine phosphorylation and transcriptional activity of STAT92E, the sole Drosophila STAT homolog. Consequently, BOT-4-one significantly inhibited STAT3 tyrosine phosphorylation and expression of STAT3 downstream target gene SOCS3 in various human cancer cell lines, and its effect was more potent in JAK3-activated Hodgkin's lymphoma cell line than in JAK2-activated breast cancer and prostate cancer cell lines. In addition, BOT-4-one-treated Hodgkin's lymphoma cells showed decreased cell survival and proliferation by inducing apoptosis through down-regulation of STAT3 downstream target anti-apoptotic gene expression. These results suggest that BOT-4-one is a novel small molecule inhibitor of JAK3/STAT3 signaling and may have therapeutic potential in the treatment of human cancers harboring aberrant JAK3/STAT3 signaling, specifically Hodgkin's lymphoma.

Uncoupling JAK3 activation induces apoptosis in human lymphoid cancer cells via regulating critical survival pathways

In the current work, we report that specific inhibition of Janus tyrosine kinase (JAK3) via NC1153 induces apoptosis of certain leukemia/lymphoma cell lines. Affymetrix microarray profiling following NC1153 treatment unveiled JAK3 dependent survival modulating pathways (p53, TGF-beta, TNFR and ER stress) in Kit225 cells. IL-2 responsive NC1153 target genes were regulated in human JAK3 positive, but not in JAK3 negative lymphoid tumor cells. Moreover, primary lymphoma samples revealed that a number of these genes were reciprocally regulated during disease progression and JAK3 inhibition suggesting that downstream targets of JAK3 could be exploited in the development of novel cancer treatment regimes.