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Osteosarcoma(OS) is a highly aggressive bone cancer for which treatment has remained essentially unchanged for decades. Although OS is characterized by extensive genomic heterogeneity and instability, RB1 and TP53 have been shown to be the most commonly inactivated tumor suppressors in OS. We previously generated a mouse model with a double knockout (DKO) of Rb1 and Trp53 within cells of the osteoblastic lineage, which largely recapitulates human OS with nearly complete penetrance. SKP2 is a repression target of pRb and serves as a substrate recruiting subunit of the SCFSKP2 complex. In addition, SKP2 plays a central role in regulating the cell cycle by ubiquitinating and promoting the degradation of p27. We previously reported the DKOAA transgenic model, which harbored a knock-in mutation in p27 that impaired its binding to SKP2. Here, we generated a novel p53-Rb1-SKP2 triple-knockout model (TKO) to examine SKP2 function and its potential as a therapeutic target in OS. First, we observed that OS tumorigenesis was significantly delayed in TKO mice and their overall survival was markedly improved. In addition, the loss of SKP2 also promoted an apoptotic microenvironment and reduced the stemness of DKO tumors. Furthermore, we found that small-molecule inhibitors of SKP2 exhibited anti-tumor activities in vivo and in OS organoids as well as synergistic effects when combined with a standard chemotherapeutic agent. Taken together, our results suggest that SKP2 inhibitors may reduce the stemness plasticity of OS and should be leveraged as next-generation adjuvants in this cancer.

Osteosarcoma is a highly aggressive malignancy for which treatment has remained essentially unchanged for years. Our previous studies found that the F-box protein SKP2 is overexpressed in osteosarcoma, acting as a proto-oncogene; p27Kip1 (p27) is an inhibitor of cyclin-dependent kinases and a downstream substrate of SKP2-mediated ubiquitination. Overexpression of SKP2 and underexpression of p27 are common characteristics of cancer cells. The SCFSKP2 E3 ligase ubiquitinates Thr187-phosphorylated p27 for proteasome degradation, which can be abolished by a Thr187Ala knock-in (p27T187A KI) mutation. RB1 and TP53 are two major tumor suppressors commonly coinactivated in osteosarcoma. We generated a mouse model with a double knockout (DKO) of Rb1 and Trp53 within cells of the osteoblastic lineage, which developed osteosarcoma with full penetrance. When p27T187A KI mice were crossed on to the DKO background, p27T187A protein was found to accumulate in osteosarcoma tumor tissues. Furthermore, p27T187A promoted apoptosis in DKO tumors, slowed disease progression, and significantly prolonged overall survival. RNA sequencing analysis also linked the SCFSKP2 -p27T187A axis to potentially reduced cancer stemness. Given that RB1 and TP53 loss or coinactivation is common in human osteosarcoma, our study suggests that inhibiting the SKP2-p27 axis may represent a desirable therapeutic strategy for this cancer.

Synovial sarcoma (SS) is an aggressive soft-tissue cancer with a poor prognosis and a propensity for local recurrence and distant metastasis. In this study, we investigated whether S phase kinase-associated protein (Skp2) plays an oncogenic role in tumor initiation, progression, and metastasis of SS. Our study revealed that Skp2 is frequently overexpressed in SS specimens and SS18-SSX transgenic mouse tumors, as well as correlated with clinical stages. Next, we identified that genetic depletion of Skp2 reduced mesenchymal and stemness markers, and inhibited the invasive and proliferative capacities of SS cell lines. Furthermore, Skp2 depletion markedly suppressed the growth of SS xenografts tumors. Treatment of SS cell lines with the skp2 inhibitor flavokawain A (FKA) reduced Skp2 expression in a dose-dependent manner and resulted in cell cycle arrest and apoptosis. FKA also suppressed the invasion and tumor-initiating properties in SS, similar to the effects of Skp2 knockdown. In addition, a combination of FKA and conventional chemotherapy showed a synergistic therapeutic efficacy. Taken together, our results suggest that Skp2 plays an essential role in the biology of SS by promoting the mesenchymal state and cancer stemness. Given that chemotherapy resistance is often associated with cancer stemness, strategies of combining Skp2 inhibitors with conventional chemotherapy in SS may be desirable.

A new style of tofu coagulated through the fermentation of Lactobacillus plantarum SJ‐L‐1 was produced. L. plantarum SJ‐L‐1 with a high growth rate and excellent acid production ability was isolated and identified from naturally fermented soy yellow whey. The gene annotation indicated the potential outstanding isoflavone conversion capacity of L. plantarum SJ‐L‐1. Furthermore, fermentation tofu was prepared using L. plantarum SJ‐L‐1 and Lactobacillus rhamnosus 1–16 as the starter microbiota. Compared to traditional MgCl2 tofu and fermented soy whey tofu, SJ‐L‐1 tofu exhibited a slight increase in hardness and better structure uniformity. SJ‐L‐1 tofu also possessed the highest levels of total isoflavone content (76.33 µg/g) and volatile compounds (561.54 µg/kg) among the four styles of tofu. This research indicated that this new type of tofu coagulated through a combination of heat and fermentation of L. plantarum SJ‐L‐1 represents a promising candidate for future functional foods. [ABSTRACT FROM AUTHOR]

Background: Sanqi Xueshangning Capsules (SXC) is a famous Chinese patent medicine with a good curative effect on various gynecological pain diseases in China. However, its chemical composition and potential active ingredients were clearly unrevealed, which hindered the elaboration of its material basis functional mechanism and clinical application. Materials and Methods: In the study, we developed an integrative ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) method coupled with SCIEX OS software for characterizing the chemical composition in SXC. The data collection was conducted using a Waters UPLCTM HSS T3 (2.1 × 100 mm, 1.8 µm) in a binary elution system. The SCIEX OS software coupled with multivariable processing techniques was used to screen absorbed prototypes in serum after oral administration of SXC. The structural identification of the components was performed by MS/MS fragmentation mechanism. Results: A total of 113 components from SXC were tentatively characterized, including 38 saponins, 13 flavonoids, 10 phenylpropanoids, 9 alkaloids, 20 organic acids, and 23 others. Based on the in vitro composition results, 21 absorbed prototypes in rat serum were identified, mainly including alkaloids, flavonoids, phenylpropanoids, and saponins. Conclusion: It was concluded that an integrative UPLC-Q-TOF-MS method coupled with SCIEX OS software could be successfully applied for the components' characterization of SXC in vitro and in vivo, which laid a reliable scientific basis for promoting the discovery of material basis and the improvement of quality control of SXC. [ABSTRACT FROM AUTHOR]