Overexpression of macrophage-colony stimulating factor-1 receptor as a prognostic factor for survival in cancer: A systematic review and meta-analysis

Role of CSF1R 550th-tryptophan in kusunokinin and CSF1R inhibitor binding and ligand-induced structural effect

Binding affinity is an important factor in drug design to improve drug-target selectivity and specificity. In this study, in silico techniques based on molecular docking followed by molecular dynamics (MD) simulations were utilized to identify the key residue(s) for CSF1R binding affinity among 14 pan-tyrosine kinase inhibitors and 15 CSF1R-specific inhibitors. We found tryptophan at position 550 (W550) on the CSF1R binding site interacted with the inhibitors' aromatic ring in a π-π way that made the ligands better at binding. Upon W550-Alanine substitution (W550A), the binding affinity of trans-(-)-kusunokinin and imatinib to CSF1R was significantly decreased. However, in terms of structural features, W550 did not significantly affect overall CSF1R structure, but provided destabilizing effect upon mutation. The W550A also did not either cause ligand to change its binding site or conformational changes due to ligand binding. As a result of our findings, the π-π interaction with W550's aromatic ring could be still the choice for increasing binding affinity to CSF1R. Nevertheless, our study showed that the increasing binding to W550 of the design ligand may not ensure CSF1R specificity and inhibition since W550-ligand bound state did not induce significantly conformational change into inactive state.

Colony-stimulating factor-1 receptor inhibition combined with paclitaxel exerts effective antitumor effects in the treatment of ovarian cancer

Ovarian cancer is the tumor with the highest mortality among gynecological malignancies. Studies have confirmed that paclitaxel chemoresistance is associated with increased infiltration of tumor-associated macrophages (TAMs) in the microenvironment. Colony-stimulating factor 1 (CSF-1) receptor (CSF-1R) plays a key role in regulating the number and differentiation of macrophages in certain solid tumors. There are few reports on the effects of targeted inhibition of CSF-1R in combination with chemotherapy on ovarian cancer and the tumor microenvironment. Here, we explored the antitumor efficacy and possible mechanisms of the CSF - 1R inhibitor pexidartinib (PLX3397) when combined with the first-line chemotherapeutic agent paclitaxel in the treatment of ovarian cancer. We found that CSF-1R is highly expressed in ovarian cancer cells and correlates with poor prognosis. Treatment by PLX3397 in combination with paclitaxel significantly inhibited the growth of ovarian cancer both in vitro and in vivo. Blockade of CSF-1R altered the macrophage phenotype and reprogrammed the immunosuppressive cell population in the tumor microenvironment.

CSF-1R in Cancer: More than a Myeloid Cell Receptor

Colony-stimulating factor 1 receptor (CFS-1R) is a myeloid receptor with a crucial role in monocyte survival and differentiation. Its overexpression is associated with aggressive tumors characterized by an immunosuppressive microenvironment and poor prognosis. CSF-1R ligands, IL-34 and M-CSF, are produced by many cells in the tumor microenvironment (TME), suggesting a key role for the receptor in the crosstalk between tumor, immune and stromal cells in the TME. Recently, CSF-1R expression was reported in the cell membrane of the cancer cells of different solid tumors, capturing the interest of various research groups interested in investigating the role of this receptor in non-myeloid cells. This review summarizes the current data available on the expression and activity of CSF-1R in different tumor types. Notably, CSF-1R+ cancer cells have been shown to produce CSF-1R ligands, indicating that CSF-1R signaling is positively regulated in an autocrine manner in cancer cells. Recent research demonstrated that CSF-1R signaling enhances cell transformation by supporting tumor cell proliferation, invasion, stemness and drug resistance. In addition, this review covers recent therapeutic strategies, including monoclonal antibodies and small-molecule inhibitors, targeting the CSF-1R and designed to block the pro-oncogenic role of CSF-1R in cancer cells.

Off-target pharmacological activity at various kinases: Potential functional and pathological side effects

In drug discovery, during the lead optimization and candidate characterization stages, novel small molecules are frequently evaluated in a battery of in vitro pharmacology assays to identify potential unintended, off-target interactions with various receptors, transporters, ion channels, and enzymes, including kinases. Furthermore, these screening panels may also provide utility at later stages of development to provide a mechanistic understanding of unexpected safety findings. Here, we present a compendium of the most likely functional and pathological outcomes associated with interaction(s) to a panel of 95 kinases based on an extensive curation of the scientific literature. This panel of kinases was designed by AbbVie based on safety-related data extracted from the literature, as well as from over 20 years of institutional knowledge generated from discovery efforts. For each kinase, the scientific literature was reviewed using online databases and the most often reported functional and pathological effects were summarized. This work should serve as a practical guide for small molecule drug discovery scientists and clinical investigators to predict and/or interpret adverse effects related to pharmacological interactions with these kinases.

Hematologic dysfunction in cancer: Mechanisms, effects on antitumor immunity, and roles in disease progression

With the major advances in cancer immunology and immunotherapy, it is critical to consider that most immune cells are short-lived and need to be continuously replenished from hematopoietic stem and progenitor cells. Hematologic abnormalities are prevalent in cancer patients, and many ground-breaking studies over the past decade provide insights into their underlying cellular and molecular mechanisms. Such studies demonstrate that the dysfunction of hematopoiesis is more than a side-effect of cancer pathology, but an important systemic feature of cancer disease. Here we review these many advances, covering the cancer-associated phenotypes of hematopoietic stem and progenitor cells, the dysfunction of myelopoiesis and erythropoiesis, the importance of extramedullary hematopoiesis in cancer disease, and the developmental origins of tumor associated macrophages. We address the roles of many secreted mediators, signaling pathways, and transcriptional and epigenetic mechanisms that mediate such hematopoietic dysfunction. Furthermore, we discuss the important contribution of the hematopoietic dysfunction to cancer immunosuppression, the possible avenues for therapeutic intervention, and highlight the unanswered questions and directions for future work. Overall, hematopoietic dysfunction is established as an active component of the cancer disease mechanisms and an important target for therapeutic intervention.

Potential Stereoselective Binding of Trans-(±)-Kusunokinin and Cis-(±)-Kusunokinin Isomers to CSF1R

Breast cancer cell proliferation and migration are inhibited by naturally extracted trans-(−)-kusunokinin. However, three additional enantiomers of kusunokinin have yet to be investigated: trans-(+)-kusunokinin, cis-(−)-isomer and cis-(+)-isomer. According to the results of molecular docking studies of kusunokinin isomers on 60 breast cancer-related proteins, trans-(−)-kusunokinin was the most preferable and active component of the trans-racemic mixture. Trans-(−)-kusunokinin targeted proteins involved in cell growth and proliferation, whereas the cis-(+)-isomer targeted proteins involved in metastasis. Trans-(−)-kusunokinin targeted CSF1R specifically, whereas trans-(+)-kusunokinin and both cis-isomers may have bound AKR1B1. Interestingly, the compound’s stereoisomeric effect may influence protein selectivity. CSF1R preferred trans-(−)-kusunokinin over trans-(+)-kusunokinin because the binding pocket required a ligand planar arrangement to form a π-π interaction with a selective Trp550. Because of its large binding pocket, EGFR exhibited no stereoselectivity. MD simulation revealed that trans-(−)-kusunokinin, trans-(+)-kusunokinin and pexidartinib bound CSF1R differently. Pexidartinib had the highest binding affinity, followed by trans-(−)-kusunokinin and trans-(+)-kusunokinin, respectively. The trans-(−)-kusunokinin-CSF1R complex was found to be stable, whereas trans-(+)-kusunokinin was not. Trans-(±)-kusunokinin, a potential racemic compound, could be developed as a selective CSF1R inhibitor when combined.

Vav1 Promotes B-Cell Lymphoma Development

Vav1 is normally and exclusively expressed in the hematopoietic system where it functions as a specific GDP/GTP nucleotide exchange factor (GEF), firmly regulated by tyrosine phosphorylation. Mutations and overexpression of Vav1 in hematopoietic malignancies, and in human cancers of various histologic origins, are well documented. To reveal whether overexpression of Vav1 in different tissues suffices for promoting the development of malignant lesions, we expressed Vav1 in transgenic mice by using the ubiquitous ROSA26 promoter (Rosa Vav1). We detected Vav1 expression in epithelial tissues of various organs including pancreas, liver, and lung. While carcinomas did not develop in these organs, surprisingly, we noticed the development of B-cell lymphomas. Rac1-GTP levels did not change in tissues from Rosa Vav1 mice expressing the transgenic Vav1, while ERK phosphorylation increased in the lymphomas, suggesting that signaling pathways are evoked. One of the growth factors analyzed by us as a suspect candidate to mediate paracrine stimulation in the lymphocytes was CSF-1, which was highly expressed in the epithelial compartment of Rosa Vav1 mice. The expression of its specific receptor, CSF-1R, was found to be highly expressed in the B-cell lymphomas. Taken together, our results suggest a potential cross-talk between epithelial cells expressing Vav1, that secrete CSF-1, and the lymphocytes that express CSF-1R, thus leading to the generation of B-cell lymphomas. Our findings provide a novel mechanism by which Vav1 contributes to tumor propagation.

Prognostic Significance of CSF-1R Expression in Early Invasive Breast Cancer

Colony-stimulating factor-1 receptor (CSF-1R) signaling promotes an immune suppressive microenvironment enriched in M2 macrophages. Given that CSF-1R inhibitors are under investigation in clinical trials, including in breast cancer, CSF-1R expression and association with immune biomarkers could identify patients who derive greater benefit from combination with immunotherapies. TIMER2.0 and bc-GenExMiner v4.7 were used to assess the correlation of CSF1R mRNA with immune infiltrates and prognosis. Following a prespecified training-validation approach, an optimized immunohistochemistry assay was applied to assess CSF-1R on carcinoma cells and macrophages on breast cancer tissue microarray series representing 2384 patients, coupled to comprehensive clinicopathological, biomarker, and outcome data. Significant positive correlations were observed between CSF1R mRNA and immune infiltrates. High carcinoma CSF-1R correlated with grade 3 tumors >2 cm, hormone receptor negativity, high Ki67, immune checkpoint biomarkers, and macrophages expressing CSF-1R and CD163. High carcinoma CSF-1R was significantly associated with poor survival in univariate and multivariate analyses. Adverse prognostic associations were retained in ER+ cases regardless of the presence of CD8+ T cells. CSF-1R+ macrophages were not prognostic. High carcinoma CSF-1R is associated with aggressive breast cancer biology and poor prognosis, particularly in ER+ cases, and identifies patients in whom biomarker-directed CSF-1R therapies may yield superior therapeutic responses.

Integrated Analysis of Transcriptome and Differential Methylation of Neurofibromatosis Type 2 Vestibular Schwannomas

BACKGROUND

Vestibular schwannoma is the third most common benign intracranial tumor that can occur sporadically or be associated with neurofibromatosis type 2 (neurofibromatosis type 2 vestibular schwannoma [NF2-VS]). The aim of this study is to provide a comprehensive bioinformatic analysis of methylated-differentially expressed genes (MDEGs) in NF2-VS.

METHODS

Transcriptional sequencing datasets (GSE141801 and GSE108524) and gene methylation microarrays (GSE56598) from the Gene Expression Omnibus database were used to identify and analyze MDEGs in NF2-VS. A protein-protein interaction (PPI) network was built, and the hub genes and modules were identified. Finally, potential pharmacotherapy targeting MDEGs were extracted for NF2-VS.

RESULTS

A total of 57 hypermethylation-low expression genes and 88 hypomethylation-high expression genes were identified. Pathways associated with aberrantly MDEGs included P13K-AKT, MAPK, and Ras, which were also involved in NF2-VS. Six hub genes (EGFR, CCND1, CD53, CSF1R, PLAU, and FGFR1) were identified from the PPI network. Modification of the aforementioned genes altered cell-to-cell communication, response to stimulus, cellular regulation, and membrane and protein bindings. Thirty drugs targeting these pathways were selected based on the hub genes.

CONCLUSIONS

Analysis of MDEGs may enrich the understanding of the molecular mechanisms of NF2-VS pathogenesis and lay the groundwork for potential biomarkers and therapeutic targets for NF2-VS.