PPARγ and C/EBPα enable adipocyte differentiation upon inhibition of histone methyltransferase PRC2 in malignant tumors.

Loss of terminal differentiation is a hallmark of cancer and offers a potential mechanism for differentiation therapy. Polycomb repressive complex 2 (PRC2) serves as the methyltransferase for K27 of histone H3 that is crucial in development. While PRC2 inhibitors show promise in treating various cancers, the underlying mechanisms remain incompletely understood. Here, we demonstrated that the inhibition or depletion of PRC2 enhanced adipocyte differentiation in malignant rhabdoid tumors and mesenchymal stem cells, through upregulation of peroxisome proliferator-activated receptor gamma (PPARG) and CEBPA. Mechanistically, PRC2 directly represses their transcription through H3K27 methylation, as both genes exhibit a bivalent state in mesenchymal stem cells. KO of PPARG compromised C/EBPα expression and impeded the PRC2 inhibitor-induced differentiation into adipocytes. Furthermore, the combination of the PPARγ agonist rosiglitazone and the PRC2 inhibitor MAK683 exhibited a higher inhibition on Ki67 positivity in tumor xenograft compared to MAK683 alone. High CEBPA, PLIN1, and FABP4 levels positively correlated with favorable prognosis in sarcoma patients in The Cancer Genome Atlas cohort. Together, these findings unveil an epigenetic regulatory mechanism for PPARG and highlight the essential role of PPARγ and C/EBPα in the adipocyte differentiation of malignant rhabdoid tumors and sarcomas with a potential clinical implication.

The fibroblast growth factor receptor antagonist SSR128129E inhibits fat accumulation via suppressing adipogenesis in mice.

BACKGROUND: AS an allosteric inhibitor of fibroblast growth factor receptors (FGFRs), SSR128129E (SSR) extensively inhibits the fibroblast growth factor (FGF) signaling. Given the metabolic importance of FGFs and the global epidemic of obesity, we explored the effect of SSR on fat metabolism. METHODS AND RESULTS: Three-week-old male mice were administered intragastrically with SSR (30 mg/kg/day) or PBS for 5 weeks. The effects of SSR on white and brown fat metabolism were investigated by respiratory metabolic monitoring, histological assessment and molecular analysis. Results indicated that SSR administration significantly reduced the body weight gain and the fat content of mice. SSR did not increase, but decreased the thermogenic capability of both brown and white fat. However, SSR markedly suppressed adipogenesis of adipose tissues. Further study demonstrated the involvement of ERK signaling in the action of SSR. CONCLUSIONS: SSR may be a promising drug candidate for the prevention of obesity via suppressing adipogenesis. However, the influence of SSR on thermogenesis in humans should be further investigated before its clinical application.

PC3-secreted microprotein is a novel chemoattractant protein and functions as a high-affinity ligand for CC chemokine receptor 2.

PC3-secreted microprotein (PSMP) or microseminoprotein is a newly discovered secreted protein whose function is currently unknown. In this study, PSMP was found to possess chemotactic ability toward monocytes and lymphocytes, and its functional receptor was identified as CCR2B. PSMP was identified as a chemoattractant protein from a PBMC chemoattractant platform screen that we established. The mature secreted PSMP was able to chemoattract human peripheral blood monocytes, PBLs, and CCR2B-expressing THP-1 cells, but not peripheral blood neutrophils, even though it does not contain the classical structure of chemokines. CCR2B was identified as one receptor for PSMP-mediated chemotaxis by screening HEK293 cells that transiently expressed classical chemokine receptors; results obtained from the chemotaxis, calcium flux, receptor internalization, and radioligand-binding assays all confirmed this finding. To further identify the major function of PSMP, we analyzed its expression profile in tissues. PSMP is highly expressed in benign prostatic hyperplasia and in some prostate cancers, and can also be detected in breast tumor tissue. In response to PSMP stimulation, phosphorylated ERK levels downstream of CCR2B signaling were upregulated in the PC3 cell line. Taken together, our data collectively suggest that PSMP is a chemoattractant protein acting as a novel CCR2 ligand that may influence inflammation and cancer development.

An antagonist for CCR4 alleviates murine allergic rhinitis by intranasal administration.

BACKGROUND: CCR4 is highly expressed on Th2 cells. These cells play an important role in acute inflammatory responses, including those involved in allergic rhinitis. We determined whether disrupting the CCR4 ligand interaction with CCR4 antagonist could alleviate allergic rhinitis in a mouse model. METHODS: BALB/c mice were sensitized with ovalbumin and alum by intraperitoneal injection and challenged with intranasally administered ovalbumin. Compound 22, which has been reported as a novel small-molecule antagonist of CCR4, was also administered intranasally. In addition, budesonide, an efficient glucocorticoid, was used as a positive control. The effects of compound 22 were quantified by multiple parameters of allergic responses in both nasal and pulmonary tissues. RESULTS: Compound 22 significantly improved symptoms of allergic rhinitis and suppressed levels of total IgE of serum. It dramatically reduced the levels of IL-4 in bronchoalveolar lavage fluid and also decreased the number of inflammatory cells in the fluid. The infiltration of inflammatory cells, especially eosinophils, was markedly reduced in the nasal and pulmonary tissues. The number of IL-4+ cells was also significantly reduced in these tissues. Moreover, the numbers of Foxp3+ cells and IL-17+ cells were reduced, though not to a statistically significant degree. CONCLUSIONS: In our research, CCR4 antagonists such as compound 22 were proven for the first time to alleviate murine allergic rhinitis when administered nasally. CCR4 antagonists may have therapeutic potential for the treatment of allergic rhinitis.

Geochemical Fractionation and Source Identification of Pb and Cd in Riparian Soils and River Sediments from Three Lower Reaches Located in the Pearl River Delta.

Pb and Cd accumulation in riparian soils and river sediments in river basins is a challenging pollution issue due to the persistence and bioaccumulation of these two trace metals. Understanding the migration characteristics and input sources of these metals is the key to preventing metal pollution. This study was conducted to explore the contents, geochemical fractionation, and input sources of Pb and Cd in riparian soils and river sediments from three lower reaches of the Pearl River Delta located in the Guangdong-Hong Kong-Macao Greater Bay Area. The total concentration of all Pb and Cd values exceeded the background values to varying degrees, and the exchangeable fraction of Cd in riparian soils and river sediments accounted for the largest proportion, while that of Pb was dominated by the residual fraction. Geoaccumulation index calculations showed that in the riparian soils, the average accumulation degree of Pb (0.52) in the Beijiang River (BJR) was the highest, while that of Cd (2.04) in the Xijiang River (XJR) was the highest. Unlike that in riparian soils, the maximum accumulation of Pb (0.76) and Cd (3.01) in river sediments both occurred in the BJR. Furthermore, the enrichment factor results also showed that Pb and Cd in the riparian soils and river sediments along the BJR were higher than those in the XJR and Dongjiang River (DJR). The relationship between enrichment factors and nonresidual fractions further proved that the enrichment factors of Cd were significantly correlated with the nonresidual fractions of Cd, which may imply various anthropogenic sources of Cd in the three reaches. Moreover, source identification based on principal component analysis (PCA) and Pb isotope ratio analysis indicated that riparian soils and river sediments have inconsistent pollution source structures. The PCA results showed that Pb and Cd were homologous inputs in the DJR, and there were significant differences only in the riparian soils and river sediments. Pb isotope tracing results further showed that the bedrock of high geological background from upstream may be the main reason for Cd accumulation in the XJR. However, the ultrahigh accumulation of Cd in the BJR is mainly caused by the input of the upstream mining and metallurgy industry. The control of upstream input sources will be the key to the prevention of trace metal pollution in these regions.

C-terminal peptides of chemokine-like factor 1 signal through chemokine receptor CCR4 to cross-desensitize the CXCR4.

CKLF1, a human cytokine that is a functional ligand for CCR4, is upregulated in various inflammation and autoimmune diseases. CKLF1 contains at least two secreted forms, the C-terminal peptides C19 and C27. Chemically synthesized C19 and C27 can interact with CCR4 and attenuate allergic inflammation. In this study, we found C19 and C27 could inhibit SDF-1-induced CXCR4-mediated chemotaxis and promote CXCR4 internalization. The inhibitory effect was due to desensitization of CXCR4, which was mediated by CCR4. Further experiments confirmed that CXCR4 desensitization required activation of PI3K/PKC pathway. Altogether our data elucidate the mechanism of C19- and C27-induced CXCR4 desensitization.

FGF2 disruption enhances thermogenesis in brown and beige fat to protect against adiposity and hepatic steatosis.

OBJECTIVE: Fibroblast growth factor 2 (FGF2) has been reported to play divergent roles in white adipogenic differentiation, however, whether it regulates thermogenesis of fat tissues remains largely unknown. We therefore aimed to investigate the effect of FGF2 on fat thermogenesis and elucidate the underlying mechanisms. METHODS: FGF2-KO and wild-type (WT) mice were fed with chow diet and high-fat diet (HFD) for 14 weeks. The brown and white fat mass, thermogenic capability, respiratory exchange ratio, and hepatic fat deposition were determined. In vitro experiments were conducted to compare the thermogenic ability of FGF2-KO- with WT-derived brown and white adipocytes. Exogenous FGF2 was supplemented to in vitro-cultured WT brown and ISO-induced beige adipocytes. The FGFR inhibitor, PPARγ agonist, and PGC-1α expression lentivirus were used with the aid of technologies including Co-IP, ChIP, and luciferase reporter assay to elucidate the mechanisms underlying the FGF2 regulation of thermogenesis. RESULTS: FGF2 gene disruption results in increased thermogenic capability in both brown and beige fat, supporting by increased UCP1 expression, enhanced respiratory exchange ratio, and elevated thermogenic potential in response to cold exposure. Thus, the deletion of FGF2 protects mice from high fat-induced adiposity and hepatic steatosis. Mechanistically, in vitro investigations indicated FGF2 acts in autocrine/paracrine fashions. Exogenous FGF2 supplementation inhibits both PGC-1α and PPARγ expression, leading to suppression of UCP1 expression in brown and beige adipocytes. CONCLUSIONS: These findings demonstrate that FGF2 is a novel thermogenic regulator, suggesting a viable potential strategy for using FGF2-selective inhibitors in combat adiposity and associated hepatic steatosis.

CMTM8 is Frequently Downregulated in Multiple Solid Tumors.

Previous studies have demonstrated that overexpression of CMTM8 inhibits cell growth and induces apoptosis in multiple types of cancer cells, whereas the downregulation of CMTM8 induces the epithelial-to-mesenchymal (EMT)-like phenotype in hepatocyte carcinoma cells, implying its important roles in tumorigenesis and tumor metastasis. No extensive studies on the expression of CMTM8 in either normal or tumorous human tissues have been reported to date. Here, using real-time quantitative polymerase chain reaction, we analyzed CMTM8 expression in multiple normal human tissue samples. Moreover, by applying high-throughput immunohistochemical staining of tissue microarrays with homemade anti-CMTM8 antibodies, we studied CMTM8 expression in carcinoma samples and adjacent normal samples of 6 types of human tissues. CMTM8 is widely expressed in many normal human tissues and is frequently downregulated or absent in multiple solid tumors (liver, lung, colon, rectum, esophagus, stomach). χ tests revealed a significant negative correlation between CMTM8 expression and tumorigenesis: liver, lung (squamous carcinoma), colon, rectum, P<0.0001; esophagus, P<0.001; stomach, P<0.01. Real-time quantitative polymerase chain reaction analysis of samples from esophageal carcinomas and the adjacent normal tissues revealed that CMTM8 mRNA levels are reduced in carcinomas compared with normal tissues, indicating that CMTM8 is potentially downregulated at the mRNA level (P<0.01). This is the first extensive study of CMTM8 expression in both normal and tumorous human tissues. Our findings strongly supported the potential role of CMTM8 as a novel tumor suppressor and may shape further functional studies on this gene.

Alleviation of murine allergic rhinitis by C19, a C-terminal peptide of chemokine-like factor 1 (CKLF1).

Human chemokine-like factor (CKLF1) is a human cytokine that exhibits chemotactic activities on a wide spectrum of leukocytes. One of CKLF1's C-terminal peptides, C19, exerts inhibitory effects on chemotaxis mediated by mouse Ccr3 and Ccr4 and human CCR3 and CCR4. Mouse models of asthma show that C19 can also inhibit the Th2 response. CCR3 and CCR4 are chemokine receptors important to allergic rhinitis, a condition whose pathogenesis is similar to that of asthma. Here, we established a mouse model of allergic rhinitis by repetitive sensitization and intranasal challenge with OVA and assessed whether C19 has therapeutic effects on this model. In this study, both intranasal and intraperitoneal administration of C19 reduced allergic symptoms such as sneezing and rubbing and serum concentration of IgE. C19 showed a strong ability to suppress eosinophil accumulation in nasal mucosa and lung tissues. C19 was able to suppress the Th2 cytokine IL-4 without augmenting the Th1 cytokine IFN-γ in BAL and IL-4(+) cells in the local nasal tissue. In terms of symptom amelioration, IgE reduction, and eosinophilia suppression, C19 was found to be as effective against allergic rhinitis as Budesonide. Moreover, intranasal treatment has a stronger therapeutic effect than other types of administration, and it may be more convenient and safe. For these reasons, C19 may have potential in the treatment of allergic rhinitis.