A novel orally available Syk/Src/Jak2 inhibitor, SKLB-850, showed potent anti-tumor activities in B cell lymphoma (BCL) models

Targeting spleen tyrosine kinase (SYK): structure, mechanisms and drug discovery

Spleen tyrosine kinase (SYK) is a crucial non-receptor tyrosine kinase involved in signaling pathways that regulate various cellular processes. It is primarily expressed in hematopoietic cells and myeloid cells, which are crucial for B-cell development, maturation and antibody production, and it is a key therapeutic target for autoimmune and allergic diseases. Overexpression of SYK is also associated with cancer and cardiovascular, cerebrovascular and neurodegenerative diseases, contributing to their initiation and progression. SYK is a promising target for drug development, and several inhibitors have already been reported. This review covers the structure and regulatory pathways of SYK, as well as its links to various diseases. It also highlights key small-molecule SYK inhibitors, their design strategies and their potential therapeutic benefits, aiming to enhance our understanding and aid in the discovery of more-effective SYK inhibitors.

Crosstalk between CXCL12/CXCR4/ACKR3 and the STAT3 Pathway

The reciprocal modulation between the CXCL12/CXCR4/ACKR3 axis and the STAT3 signaling pathway plays a crucial role in the progression of various diseases and neoplasms. Activation of the CXCL12/CXCR4/ACKR3 axis triggers the STAT3 pathway through multiple mechanisms, while the STAT3 pathway also regulates the expression of CXCL12. This review offers a thorough and systematic analysis of the reciprocal regulatory mechanisms between the CXCL12/CXCR4/ACKR3 signaling axis and the STAT3 signaling pathway in the context of diseases, particularly tumors. It explores the potential clinical applications in tumor treatment, highlighting possible therapeutic targets and novel strategies for targeted tumor therapy.

Vortioxetine hydrobromide inhibits the growth of gastric cancer cells in vivo and in vitro by targeting JAK2 and SRC

Gastric cancer is the fourth leading cause of cancer deaths worldwide. Most patients are diagnosed in the advanced stage. Inadequate therapeutic strategies and the high recurrence rate lead to the poor 5-year survival rate. Therefore, effective chemopreventive drugs for gastric cancer are urgently needed. Repurposing clinical drugs is an effective strategy for discovering cancer chemopreventive drugs. In this study, we find that vortioxetine hydrobromide, an FDA-approved drug, is a dual JAK2/SRC inhibitor, and has inhibitory effects on cell proliferation of gastric cancer. Computational docking analysis, pull-down assay, cellular thermal shift assay (CETSA) and in vitro kinase assays are used to illustrate vortioxetine hydrobromide directly binds to JAK2 and SRC kinases and inhibits their kinase activities. The results of non-reducing SDS-PAGE and Western blotting indicate that vortioxetine hydrobromide suppresses STAT3 dimerization and nuclear translocation activity. Furthermore, vortioxetine hydrobromide inhibits the cell proliferation dependent on JAK2 and SRC and suppresses the growth of gastric cancer PDX model in vivo. These data demonstrate that vortioxetine hydrobromide, as a novel dual JAK2/SRC inhibitor, curbs the growth of gastric cancer in vitro and in vivo by JAK2/SRC-STAT3 signaling pathways. Our results highlight that vortioxetine hydrobromide has the potential application in the chemoprevention of gastric cancer.

Phosphorylation of PBK/TOPK Tyr74 by JAK2 promotes Burkitt lymphoma tumor growth

Burkitt lymphoma (BL), which is characterized by high invasiveness, is a subgroup of non-Hodgkin lymphoma. Although BL is regarded as a highly curable disease, especially for children, some patients unfortunately still do not respond adequately. The understanding of the etiology and molecular mechanisms of BL is still limited, and targeted therapies are still lacking. Here, we found that T-LAK cell-derived protein kinase (TOPK) and phosphorylated Janus kinase 2 (p-JAK2) are highly expressed in the tissues of BL patients. We report that TOPK directly binds to and is phosphorylated at Tyr74 by JAK2. Histone H3, one of the downstream targets of TOPK, is also phosphorylated in vivo and in vitro. Furthermore, we report that the phosphorylation of TOPK at Tyr74 by JAK2 plays a vital role in the proliferation of BL cells and promotes BL tumorigenesis in vivo. Phosphorylation of TOPK at Tyr74 by JAK2 enhances the stability of TOPK. Collectively, our results suggest that the JAK2/TOPK/histone H3 axis plays a key role in the proliferation of BL cells and BL tumorigenesis in vivo.

Potential Synthetic Lethality for Breast Cancer: A Selective Sirtuin 2 Inhibitor Combined with a Multiple Kinase Inhibitor Sorafenib

Sorafenib is a clinically useful multiple kinase inhibitor for the treatment of kidney cancer, liver cancer and acute myelocytic leukemia, while it has shown weak efficacy in suppressing breast cancer. Since sirtuin2 (SIRT2) is an important epigenetic regulator and associated with several cancer types including breast cancer, development and evaluation of new SIRT2 inhibitors to probe their therapeutic potentials is currently desirable. A highly selective SIRT2 inhibitor named I was previously developed by us, which showed activity to inhibit non-small cell lung cancer cell lines in vitro. We herein report expanded screening of I and its structurally similar inactive compound II against other cancer cell lines, and found that I had a wide spectrum of anticancer activity while II had no such effects. The I-sorafenib combination treatment exerted obvious synergistic reduction on cell viability of MCF-7 cells. We observed that the combination treatment could suppress cell proliferation, survival and migration, arrest cell cycle at G0/G1 phase, and induce apoptosis in MCF-7 cells, when compared with the single treatment. In vivo studies revealed that the combination treatment showed stronger tumor growth inhibition (87%), comparing with I-(42.8%) or sorafenib-solely-treated groups (61.1%) in MCF-7 xenograft model. In conclusion, this work clearly revealed a potential synthetic lethality effect for I combined with sorafenib, and will probably offer a new strategy at least for breast cancer treatment.