Spleen tyrosine kinase activity regulates epidermal growth factor receptor signaling pathway in ovarian cancer

Involvement of the AKT Pathway in Resistance to Erlotinib and Cabozantinib in Triple-Negative Breast Cancer Cell Lines

Resistance to protein tyrosine kinase inhibitors (TKIs) presents a significant challenge in therapeutic target development for cancers such as triple-negative breast cancer (TNBC), where conventional therapies are ineffective at combatting systemic disease. Due to increased expression, the receptor tyrosine kinases EGFR (epidermal growth factor receptor) and c-Met are potential targets for treatment. However, targeted anti-EGFR and anti-c-Met therapies have faced mixed results in clinical trials due to acquired resistance. We hypothesize that adaptive responses in regulatory kinase networks within the EGFR and c-Met signaling axes contribute to the development of acquired erlotinib and cabozantinib resistance. To test this, we developed two separate models for cabozantinib and erlotinib resistance using the MDA-MB-231 and MDA-MB-468 cell lines, respectively. We observed that erlotinib- or cabozantinib-resistant cell lines demonstrate enhanced cell proliferation, migration, invasion, and activation of EGFR or c-Met downstream signaling (respectively). Using a SILAC (Stable Isotope Labeling of Amino acids in Cell Culture)-labeled quantitative mass spectrometry proteomics approach, we assessed the effects of erlotinib or cabozantinib resistance on the phosphoproteome, proteome, and kinome. Using this integrated proteomics approach, we identified several potential kinase mediators of cabozantinib resistance and confirmed the contribution of AKT1 to erlotinib resistance in TNBC-resistant cell lines.

Microplastics induce immune suppression via S100A8 downregulation

Microplastic (MP) pollution has been largely reported in the daily consumption of water and food, however, the toxicities of MPs to human beings remain largely uncovered. We found that MPs in drinking water significantly impaired mouse immune function by reducing spleen weight, CD8⁺ T cell amount and raising CD4⁺ to CD8⁺ T cell ratio. We performed proteomics and phosphoproteomics by LC-MS/MS and found MPs significantly induced 130 and 57 proteins upregulated in proteome and phosphoproteome, and 191 and 37 proteins downregulated in proteome and phosphoproteome, separately. Bioinformatic analysis show that asthma, mineral absorption, and the IL-17 signaling pathway were significantly enriched and may be involved in MP-induced spleen damage and immune suppression. We verified the top 3 differentially expressed proteins and phosphoproteins by western blot, and we further showed that S100A8 was significantly downregulated by MPs via histochemistry staining. Our results revealed that MPs can induce spleen damage and immune suppression by reducing S100A8 expression, suggesting an underestimated influence and mechanism of MPs on the mammalian immune system.

Dual inhibition of reactive oxygen species and spleen tyrosine kinase as a therapeutic strategy in liver fibrosis

Hepatic stellate cells (HSCs) play key roles in liver fibrosis (LF) and hepatocellular carcinoma (HCC). We previously reported that spleen tyrosine kinase (SYK) is critical for HSCs activation, however, the mechanisms are insufficiently understood. In the present study, we found that SYK facilitated autophagy to promote HSCs activation by enhancing reactive oxygen species (ROS) generation. However, SYK inhibitor GS-9973 could efficiently reduce HSCs ROS generation in vitro but not in vivo. Mechanistically, hepatocytes (HCs) would release ROS outside and then diffuse into HSCs to promote autophagy and activation in vitro in the context of inflammation. We then further examined the ROS contents in liver sections and primary liver cells of carbon tetrachloride (CCl4) induced mice treated with or without different doses of Silybin, a natural compound characterized by a well-established antioxidant and hepatoprotective properties, and found that ROS intensities in both liver sections and their deprived primary cells were efficiently inhibited in a dose-dependent fashion. Lastly, we evaluated the rational combination of Silybin and GS-9973 in the treatment of CCl4 induced mice and found that this combination is well tolerated and acts synergistically against HSCs activity, LF and HCC. The combinational use of Silybin and GS-9973 could be a promising therapeutic strategy in patients suffering from LF and even HCC.

Expression and molecular profiles of the AlkB family in ovarian serous carcinoma

AlkB family of Fe (II) and α-ketoglutarate-dependent dioxygenases plays essential roles in development of ovarian serous carcinoma (OV). However, the molecular profiles of AlkB family in OV have not been clarified. The results indicated that the expression of ALKBH1/3/5/8 and FTO was lower in OV patients while ALKBH2/4/6/7 expression was higher. There was a strong correlation between ALKBH5/7 and pathological stage of OV patients. Kaplan-Meier plotter revealed that OV patients with high ALKBH4 level showed longer overall survival (OS). However, patients with high levels of ALKBH5/6 and FTO showed shorter OS and progression-free survival (PFS). Genetic alterations using cBioPortal revealed that the alteration rates of FTO were the highest. We also found that the functions of AlkB family were linked to several cancer-associated signaling pathways, including chemokine receptor signaling. TIMER database indicated that the AlkB family had a strong relationship with the infiltration of six types of immune cells (macrophages, neutrophils, CD8+ T-cells, B-cells, CD4+ T-cells and dendritic cells). Next, DiseaseMeth databases revealed that the global methylation levels of ALKBH1/2/3/4/5/6/7/8 and FTO were all lower in OV patients. Thus, our findings will enhance the understanding of AlkB family in OV pathology, and provide novel insights into AlkB-targeted therapy for OV patients.

Development of a sensitive UHPLC-MS/MS method for the pharmacokinetics study of a novel tyrosine kinase inhibitors, 1-[4-(4-{5-Chloro-4-[2-(propane-2-sulfonyl)-phenylamino]-pyrimidin-2-ylamino}-phenyl)-piperazin-1-yl]-propenone in rats

Targeted inhibition of epidermal growth factor receptor has become an important means of chemotherapy for nonsmall cell lung cancer, breast cancer, pancreatic cancer, colon cancer and other malignant tumors. Although remarkable curative effects have been achieved in the past few decades, the emergence of drug resistance is a problem. Therefore, new inhibitors need to be developed. XHL-31 is a new candidate with significant inhibitory activity against T790M and C797S mutations in vitro. In order to study the pharmacokinetics in vivo, a sensitive and efficient UHPLC-MS/MS method was developed for the determination of XHL-31 in rat plasma in this study. The lower limit of quantitation of this method was 1 ng/ml and the linear range was 1-2,000 ng/ml. Method validation showed a high accuracy and precision, a high stability, a high recovery and repeatability. The method was successfully applied to the pharmacokinetic study of XHL-31 in rats. The results indicated that there were significant gender differences in oral absorption and the absolute bioavailability of XHL-31 in female rats were extremely low (<10%).

Phosphoproteomic strategies in cancer research: a minireview

Understanding the cellular processes is central to comprehend disease conditions and is also true for cancer research. Proteomic studies provide significant insight into cancer mechanisms and aid in the diagnosis and prognosis of the disease. Phosphoproteome is one of the most studied complements of the whole proteome given its importance in the understanding of cellular processes such as signaling and regulations. Over the last decade, several new methods have been developed for phosphoproteome analysis. A significant amount of these efforts pertains to cancer research. The current use of powerful analytical instruments in phosphoproteomic approaches has paved the way for deeper and sensitive investigations. However, these methods and techniques need further improvements to deal with challenges posed by the complexity of samples and scarcity of phosphoproteins in the whole proteome, throughput and reproducibility. This review aims to provide a comprehensive summary of the variety of steps used in phosphoproteomic methods applied in cancer research including the enrichment and fractionation strategies. This will allow researchers to evaluate and choose a better combination of steps for their phosphoproteome studies.

Osteoclast Signal Transduction During Bone Metastasis Formation

Osteoclasts are myeloid lineage-derived bone-resorbing cells of hematopoietic origin. They differentiate from myeloid precursors through a complex regulation process where the differentiation of preosteoclasts is followed by intercellular fusion to generate large multinucleated cells. Under physiological conditions, osteoclastogenesis is primarily directed by interactions between CSF-1R and macrophage colony-stimulating factor (M-CSF, CSF-1), receptor activator of nuclear factor NF-κB (RANK) and RANK ligand (RANKL), as well as adhesion receptors (e.g., integrins) and their ligands. Osteoclasts play a central role in physiological and pathological bone resorption and are also required for excessive bone loss during osteoporosis, inflammatory bone and joint diseases (such as rheumatoid arthritis) and cancer cell-induced osteolysis. Due to the major role of osteoclasts in these diseases the better understanding of their intracellular signaling pathways can lead to the identification of potential novel therapeutic targets. Non-receptor tyrosine kinases and lipid kinases play major roles in osteoclasts and small-molecule kinase inhibitors are emerging new therapeutics in diseases with pathological bone loss. During the last few years, we and others have shown that certain lipid (such as phosphoinositide 3-kinases PI3Kβ and PI3Kδ) and tyrosine (Src−family and Syk) kinases play a critical role in osteoclast differentiation and function in humans and mice. Some of these signaling pathways shows similarity to immunoreceptor-like receptor signaling and involves important other enzymes (e.g., PLCγ2) and adapter proteins (such as the ITAM−bearing adapters DAP12 and the Fc-receptor γ-chain). Here, we review recently identified osteoclast signaling pathways and their role in osteoclast differentiation and function as well as pathological bone loss associated with osteolytic tumors of the bone. A better understanding of osteoclast signaling may facilitate the design of novel and more efficient therapies for pathological bone resorption and osteolytic skeletal metastasis formation.