Fucoxanthin triggers ferroptosis in glioblastoma cells by stabilizing the transferrin receptor.

Glioblastoma (GBM) is the most common and lethal tumor in the world, possessing high stemness, aggressiveness and resistance. Fucoxanthin is a bio-active compound extracted from seaweeds that shows anti-tumor effects to different types of tumors. Here, we show that fucoxanthin inhibits the survival of GBM cells by triggering ferroptosis, a ferric ion and reactive oxygen species (ROS) dependent cell death and ferrostatin-1 could block it. Furthermore, we identified that fucoxanthin targets the transferrin receptor (TFRC). Fucoxanthin is able to block degradation and maintain high levels of TFRC, and similarly inhibits the growth of GBM xenografts in vivo, downregulates the expression of proliferating cell nuclear antigen (PCNA) and upregulates the levels of TFRC in tumor tissues. In conclusion, we demonstrate that fucoxanthin has a significant anti-GBM effect by triggering ferroptosis.

CRMP2 is a therapeutic target that suppresses the aggressiveness of breast cancer cells by stabilizing RECK.

Metastatic breast cancer is characterized by high mortality and limited therapeutic target. During tumor metastasis, cytoskeletal reorganization is one of the key steps in the migration and invasion of breast cancer cells. Collapsin response mediator protein 2 (CRMP2) is a cytosolic phosphoprotein that plays an important role in regulating cytoskeletal dynamics. Previous researches have reported that altered CRMP2 expression is associated with breast cancer progression, but the underlying mechanism remains poorly understood. Here, we show that CRMP2 expression is reduced in various subtypes of breast cancers and negatively correlated with lymphatic metastasis. Overexpression of CRMP2 significantly inhibits invasion and stemness in breast cancer cells, while downregulation of CRMP2 promotes cell invasion, which is not required for tubulin polymerization. Mechanistic studies demonstrate that CRMP2 interacts with RECK, prevents RECK degradation, which, in turn, blocks NF-κB and Wnt signaling pathways. Furthermore, we find that phosphorylation of CRMP2 at T514 and S522 remarkably abolishes its functions to bind with RECK and to inhibit cell invasion. Pharmacologic rescue of CRMP2 expression suppressed breast cancer metastasis in vitro and in vivo and stimulated a synergetic effect with FN-1501 that induces CRMP2 dephosphorylation. Collectively, this study highlights the potential of CRMP2 as a therapeutic target in breast cancer metastasis and reveals a distinct mechanism of CRMP2.

Flavonoid VI-16 protects against DSS-induced colitis by inhibiting Txnip-dependent NLRP3 inflammasome activation in macrophages via reducing oxidative stress.

Emerging evidence suggests that NLRP3 inflammasome was associated with various kinds of immunological diseases including colitis. However, there are few drugs targeting inflammasomes in the treatment of colitis. Several flavonoids have been found to affect the inflammasome pathway, but the mechanism is still confusing. Here we report that VI-16, a synthetic flavonoid compound, exerts potent anti-inflammatory effects on macrophages in DSS-induced colitis mice, which intervened in the activation of NLRP3 inflammasome without affecting intestinal epithelial cells. However, the protection of VI-16 against DSS-induced colitis was dependent on NLRP3 expression in hematopoietic cells. Furthermore, this inhibitory effect of VI-16 was found to be at least partially achieved by decreasing the mitochondrial ROS generation without affecting autophagy. Further studies confirm that VI-16 inhibits the binding of Txnip to NLRP3 by reducing oxidative stress and ultimately inhibits NLRP3 inflammasome. This demonstrates the ability of VI-16 to inhibit the NLRP3 inflammasome activation and its potential use in the treatment of inflammatory bowel disease.

Wogonoside impedes the progression of acute myeloid leukemia through inhibiting bone marrow angiogenesis.

Decreasing bone marrow (BM) microvessel density and circulating angiogenic cytokine levels are promising strategies for the treatment of relapsed and resistant acute myeloid leukemia (AML). Previous studies have reported that wogonoside could inhibit the progression of AML and suppress angiogenesis in a solid tumor, but the correlation of these two effects was ignored. In this research, we determined whether wogonoside could inhibit angiogenesis in this hematologic malignancy. We found that wogonoside could inhibit tumor growth and progression, and prolong the survival of nude mice inoculated with U937/MDR. Besides, reducing BM angiogenesis might cause therapeutic effect against resistant AML. Therefore, coculture between AML cells and BM stromal cells was established to imitate their crosstalk. Then, the effect of wogonoside on BM angiogenesis was tested in vitro and in vivo. We found that wogonoside could suppress microvessel formation in the chicken chorioallantoic membrane assay model and matrigel plug assay. The mechanism research revealed that wogonoside could block the JAK2-STAT3 pathway in AML cells and stromal cells to break their positive feedback. We detected several cytokines related to AML or angiogenesis and found that secreted interleukin-8 was a significant angiogenic cytokine to induce BM angiogenesis. These findings supported that new diagnostics and promising treatment strategies could be developed in relapsed and resistant AML patients.

Anlotinib inhibits angiogenesis via suppressing the activation of VEGFR2, PDGFRß and FGFR1.

Tumor cells recruit vascular endothelial cells and circulating endothelial progenitor cells to form new vessels to support their own growth and metastasis. VEGF, PDGF-BB and FGF-2 are three major pro-angiogenic factors and applied to promote angiogenesis. In this research, we demonstrated that anlotinib, a potent multi-tyrosine kinases inhibitor (TKI), showed a significant inhibitory effect on VEGF/PDGF-BB/FGF-2-induced angiogenesis in vitro and in vivo. Wound healing assay, chamber directional migration assay and tube formation assay indicated that anlotinib inhibited VEGF/PDGF-BB/FGF-2-induced cell migration and formation of capillary-like tubes in endothelial cells. Furthermore, anlotinib suppressed blood vessels sprout and microvessel density in rat aortic ring assay and chicken chorioallantoic membrane (CAM) assay. Importantly, according to our study, the anti-angiogenic effect of anlotinib is superior to sunitinib, sorafenib and nintedanib, which are three main anti-angiogenesis drugs in clinic. Mechanistically, anlotinib inhibits the activation of VEGFR2, PDGFRß and FGFR1 as well their common downstream ERK signaling. Therefore, anlotinib is a potential agent to inhibit angiogenesis and be applied to tumor therapy.

LYG-202 inhibits activation of endothelial cells and angiogenesis through CXCL12/CXCR7 pathway in breast cancer.

Angiogenesis is critical for the growth and metastasis of triple-negative breast cancer (TNBC) and its inhibition reduces the risk of progression of metastatic TNBC. In this study, we investigated that LYG-202, a flavonoid with a piperazine substitution, inhibited angiogenesis induced by conditioned media (CM) from MDA-MB-231 cells under hypoxia and revealed its underlying mechanism. The results showed that LYG-202 decreased CXCL12 secretion and CXCR7 expression, leading to suppression of its downstream ERK/AKT/nuclear factor kappa B (NF-κB) signaling, which eventually decreased the expression of MMP-2, MMP-9, RhoA and increased VE-cadherin expression in EA.hy 926 cells treated with CM from MDA-MB-231 cells under hypoxia. The decreased migration ability, increased cell adhesion and inhibited CXCR7 pathway by LYG-202 could also be reproduced in human umbilical vein endothelial cells. More importantly, LYG-202 also inhibited tumor angiogenesis and tumor growth of human breast cancer MDA-MB-231 cells in nude mice through CXCL12/CXCR7 pathway. In summary, LYG-202 is a potential agent to prohibit tumor angiogenesis through inhibiting the activation of endothelial cells.

LW-215, a newly synthesized flavonoid, exhibits potent anti-angiogenic activity in vitro and in vivo.

LW-215 is a newly synthesized flavonoid, which is the derivative of wogonin. Our group has previously confirmed that wogonin has an anti-angiogenic activity, while the anti-angiogenic effect of LW-215 is unclear. In this study, we explored whether LW-215 can inhibit angiogenesis and further probed the potential molecular mechanisms. We found that LW-215 inhibited migration and tube formation in human umbilical vein endothelial cells (HUVECs) and immortalized endothelial EA.hy926 cells without a significant decrease in cell viability. Microvessels sprouting from rat aortic ring and chicken chorioallantoic membrane (CAM) model also revealed that LW-215 could suppress angiogenesis in vivo. Western blot and ELISA analysis indicated that LW-215 could prevent VEGFR2 activation though reducing VEGF autocrine other than VEGFR1. Thus, its downstream kinases, such as Akt, ERK and p38 signaling, were inhibited. Taken together, these results fully showed that LW-215 might be a promising anti-angiogenesis agent.

Oroxyloside inhibits angiogenesis through suppressing internalization of VEGFR2/Flk-1 in endothelial cells.

Increasing flavonoids have been reported to possess anti-angiogenic effects. Inhibition of angiogenesis plays a critical role in the treatment of cancer, especially in advanced metastatic cancer. In this study, we assessed the effect of Oroxylin A-7-glucuronide (Oroxyloside), a main metabolite of Oroxylin A, on angiogenesis in human endothelial cell-like EA.hy926 cells. Oroxyloside suppressed the migration and tube formation of EA.hy926 cells. Meanwhile, microvessels sprouting from aortic rings and new blood vessels on the chicken chorioallantoic membrane (CAM) were also inhibited. Mechanism studies showed that Oroxyloside reduced the autophosphorylation of vascular endothelial growth factor receptor 2 (VEGFR2/Flk-1) while it up-regulated the expression of R-Ras and VE-cadherin. In consequence, Oroxyloside inhibited the downstream Akt/MAPK/NF-κB pathways and then decreased the nuclear translocation and DNA binding ability of NF-κB. Furthermore, in vivo study showed that Oroxyloside exhibited a potential anti-angiogenic effect in Matrigel plug assay and inhibited growth of xenografted tumors with low systemic toxicity, which could be ascribed to the inhibition of VEGFR2 internalization. Taken together, these results suggested that Oroxyloside could inhibit angiogenesis in vitro and in vivo via suppressing the internalization of VEGFR2 and might serve as a potential antitumor agent.

Heat Shock-induced Phosphorylation of TAR DNA-binding Protein 43 (TDP-43) by MAPK/ERK Kinase Regulates TDP-43 Function.

TAR DNA-binding protein (TDP-43) is a highly conserved and essential DNA- and RNA-binding protein that controls gene expression through RNA processing, in particular, regulation of splicing. Intracellular aggregation of TDP-43 is a hallmark of amyotrophic lateral sclerosis and ubiquitin-positive frontotemporal lobar degeneration. This TDP-43 pathology is also present in other types of neurodegeneration including Alzheimer's disease. We report here that TDP-43 is a substrate of MEK, a central kinase in the MAPK/ERK signaling pathway. TDP-43 dual phosphorylation by MEK, at threonine 153 and tyrosine 155 (p-T153/Y155), was dramatically increased by the heat shock response (HSR) in human cells. HSR promotes cell survival under proteotoxic conditions by maintaining protein homeostasis and preventing protein misfolding. MEK is activated by HSR and contributes to the regulation of proteome stability. Phosphorylated TDP-43 was not associated with TDP-43 aggregation, and p-T153/Y155 remained soluble under conditions that promote protein misfolding. We found that active MEK significantly alters TDP-43-regulated splicing and that phosphomimetic substitutions at these two residues reduce binding to GU-rich RNA. Cellular imaging using a phospho-specific p-T153/Y155 antibody showed that phosphorylated TDP-43 was specifically recruited to the nucleoli, suggesting that p-T153/Y155 regulates a previously unappreciated function of TDP-43 in the processing of nucleolar-associated RNA. These findings highlight a new mechanism that regulates TDP-43 function and homeostasis through phosphorylation and, therefore, may contribute to the development of strategies to prevent TDP-43 aggregation and to uncover previously unexplored roles of TDP-43 in cell metabolism.