Discovery of Potent and Orally Bioavailable Platelet-Derived Growth Factor Receptor (PDGFR) Inhibitors for the Treatment of Osteosarcoma

Identification of DDX5 as a Potential Therapeutic Target of Osteosarcoma Using Thiazolone Probes

Osteosarcoma (OS) is a rare malignant tumor that has predominantly affected children and adolescents in the past 50 years. The genomes of OS tumors exhibit a high degree of complexity, which leads to the great challenge of target identification for anti-OS. To date, no efficient therapeutic target for the treatment of OS has been validated in clinical practice. In our previous drug hunting for the treatment of OS by phenotypic screening, we found that thiazolone derivate (R)-8i was an effective and selective inhibitor against OS in MNNG/HOS cells and in vivo. However, the mechanism of action and specific molecular targets of (R)-8i remain unclear. In this study, we design and synthesize the photo-cross-linking probes based on the lead compound (R)-8i and identify DDX5 as a potential target protein using an activity-based protein profiling strategy. Further experiments including Western blot, shRNA knockdown experiments, cell colony formation, wound healing assays, and cellular thermal shift assays support that (R)-8i binds to DDX5 and induces its degradation, which affect cell proliferation and migration through the PI3K-AKT-mTOR signaling pathway. The research shows that DDX5 is a potential therapeutic target for the treatment of OS.

Discovery of potent thiazolidin-4-one sulfone derivatives for inhibition of proliferation of osteosarcoma in vitro and in vivo

Chemotherapy combining with surgical treatment has been the main strategy for osteosarcoma treatment in clinical. Due to unclear pathogenesis and unidentified drug targets, significant progress has not been made in the development of targeted drugs for osteosarcoma during the past 50 years. Our previous discovery reported compound R-8i with a high potency for the treatment of osteosarcoma by phenotypic screening. However, both the metabolic stability and bioavailability of R-8i are poor (T1/2 = 5.36 min, mouse liver microsome; and bioavailability in vivo F = 52.1 %, intraperitoneal administration) which limits it use for further drug development. Here, we described an extensive structure-activity relationship study of thiazolidine-4-one sulfone inhibitors from R-8i, which led to the discovery of compound 68. Compound 68 had a potent cellular activity with an IC50 value of 0.217 μM, much higher half-life (T1/2 = 73.8 min, mouse liver microsome) and an excellent pharmacokinetic profile (in vivo bioavailability F = 115 %, intraperitoneal administration). Compound 68 also showed good antitumor effects and low toxicity in a xenograft model (44.6 % inhibition osteosarcoma growth in BALB/c mice). These results suggest that compound 68 is a potential drug candidate for the treatment of osteosarcoma.

In vitro and in vivo anticancer activity of novel Rh(III) and Pd(II) complexes with pyrazolopyrimidine derivatives

Six pyrazolopyrimidine rhodium(III) or palladium(II) complexes, [Rh(L1)(H2O)Cl3] (1), [Rh(L2)(CH3OH)Cl3] (2), [Rh(L3)(H2O)Cl3] (3), [Rh2(L4)Cl6]·CH3OH (4), [Rh(L5)(CH3CN)Cl3]·0.5CH3CN (5), and [Pd(L5)Cl2] (6), were synthesized and characterized. These complexes showed high cytotoxicity against six tested cancer cell lines. Most of the complexes showed higher cytotoxicity to T-24 cells in vitro than cisplatin. Mechanism studies indicated that complexes 5 and 6 induced G2/M phase cell cycle arrest through DNA damage, and induced apoptosis via endoplasmic reticulum stress response. In addition, complex 5 also induced cell apoptosis via mitochondrial dysfunction. Complexes 5 and 6 showed low in vivo toxicity and high tumor growth inhibitory activity in mouse tumor models. The inhibitory effect of rhodium complex 5 on tumor growth in vivo was more pronounced than that of palladium complex 6.

Design, synthesis, and biological evaluation of 1,6-naphthyridine-2-one derivatives as novel FGFR4 inhibitors for the treatment of colorectal cancer

Aberrant FGFR4 signaling has been implicated in the development of several cancers, making FGFR4 a promising target for cancer therapy. Several FGFR4-selective inhibitors have been developed, yet none of them have been approved. Herein, we report a novel series of 1,6-naphthyridine-2-one derivatives as potent and selective inhibitors targeting FGFR4 kinase. Preliminary structure-activity relationship analysis was conducted. The screening cascades revealed that 19g was the preferred compound among the prepared series. 19g demonstrated excellent kinase selectivity and substantial cytotoxic effect against all tested colorectal cancer cell lines. 19g induced significant tumor inhibition in a HCT116 xenograft mouse model without any apparent toxicity. Notably, 19g exhibited excellent potency in disrupting the phosphorylation of FGFR4 and downstream signaling proteins mediated by FGF18 and FGF19. Compound 19g might be a potential antitumor drug candidate for the treatment of colorectal cancer.

The role of platelets in the regulation of tumor growth and metastasis: the mechanisms and targeted therapy

Platelets are a class of pluripotent cells that, in addition to hemostasis and maintaining vascular endothelial integrity, are also involved in tumor growth and distant metastasis. The tumor microenvironment is a complex and comprehensive system composed of tumor cells and their surrounding immune and inflammatory cells, tumor-related fibroblasts, nearby interstitial tissues, microvessels, and various cytokines and chemokines. As an important member of the tumor microenvironment, platelets can promote tumor invasion and metastasis through various mechanisms. Understanding the role of platelets in tumor metastasis is important for diagnosing the risk of metastasis and prolonging survival. In this study, we more fully elucidate the underlying mechanisms by which platelets promote tumor growth and metastasis by modulating processes, such as immune escape, angiogenesis, tumor cell homing, and tumor cell exudation, and further summarize the effects of platelet-tumor cell interactions in the tumor microenvironment and possible tumor treatment strategies based on platelet studies. Our summary will more comprehensively and clearly demonstrate the role of platelets in tumor metastasis, so as to help clinical judgment of the potential risk of metastasis in cancer patients, with a view to improving the prognosis of patients.

cyy260 suppresses the proliferation, migration and tumor growth of osteosarcoma by targeting PDGFR-β signaling pathway

Osteosarcoma (OS) is a group of malignant tumors with high rates of malignancy and metastasis. OS most commonly affects adolescents and young individuals. However, owing to the lack of effective targeted treatments, the 5-year survival rate for OS is still around 20%. Thus, it is essential to develop effective drugs with low toxicity for OS treatment. In the present study, we investigated the antitumor effect and underlying mechanism of cyy260 in OS via suppressing PDGFR-β and its downstream pathway. We demonstrated that cyy260 inhibits OS cell proliferation and promotes apoptosis via inducing DNA damage and causing cell cycle arrest. More importantly, cyy260 also significantly inhibits tumor migration. Further analysis of molecular mechanisms confirmed that PDGFR-β and its downstream AKT, STAT3, and ERK were involved in the cyy260-mediated antitumor effect. Analysis of subcutaneously transplanted tumors in mice showed that cyy260 suppressed tumor cell growth and exhibited low toxicity in vivo. Collectively, these findings proved that cyy260 could serve as a promising PDGFR-β inhibitor for the treatment of OS.

Osteosarcoma subtypes based on platelet-related genes and tumor microenvironment characteristics

Background

Osteosarcoma is a common metastatic tumor in children and adolescents. Because of its easy metastasis, patients often show a poor prognosis. Recently, researchers have found that platelets are closely related to metastasis of a variety of malignant tumors, but the role of platelets related characteristics in osteosarcoma is still unknown. The purpose of this study is to explore the characteristics of platelet-related subtypes and cell infiltration in tumor microenvironment.

Methods

We collected osteosarcoma cohorts from TCGA and GEO databases, and explored the molecular subtypes mediated by platelet-related genes and the related TME cell infiltration according to the expression of platelet-related genes in osteosarcoma. In addition, we also explored the differentially expressed genes (DEGs) among different molecular subtypes and established a protein-protein interaction network (PPI). Then we constructed a platelet scoring model by Univariate cox regression and least absolute shrinkage and selection operator (Lasso) cox regression model to quantify the characteristics of platelet in a single tumor. RT-PCR was used to investigate the expression of six candidate genes in osteosarcoma cell lines and normal osteoblast lines. Finally, we also predicted potential drugs with therapeutic effects on platelet-related subtypes.

Results

We found that platelet-related genes (PRGs) can distinguish osteosarcoma into two different platelet-related subtypes, C1 and C2. And the prognosis of the C2 subtype was significantly worse than that of C1 subtype. The results of ESTIMATE analysis and GO/KEGG enrichment showed that the differences between different subtypes were mainly concentrated in immune response pathways, and the immune response of C2 was inhibited relative to C1. We further studied the relationship between platelet-related subtypes and immune cell infiltration. We found that the distribution of most immune cells in C1 subtype was higher than that in C2 subtype, and there was a correlation between C1 subtype and more immune cells. Finally, we screened the PRGs related to the prognosis of osteosarcoma through Univariate Cox regression, established independent prognostic platelet characteristics consisting of six genes to predict the prognosis of patients with OS, and predicted the drugs that may be used in the treatment of osteosarcoma. RT-PCR was used to verify the expression of candidate genes in osteosarcoma cells.

Conclusion

Platelet scoring model is a significant biomarker, which is of great significance to determine the prognosis, molecular subtypes, characteristics of TME cell infiltration and therapy in patients with OS.