DKK1 determines organotropism of breast cancer metastasis by regulating microenvironments

Supported by the National Natural Science Foundation of China,a collaborative study by the laboratories of Dr.Hu Guohong(胡国宏)from Shanghai Institutes for Biological Sciences,Chinese Academy of Sciences and Dr.Yang Qifeng(杨其峰)from Shangdong University demonstrates that Dickkopf1(DKK1)

Organ-specific enhancement of metastasis by spontaneous ploidy duplication and cell size enlargement

Aneuploidy is commonly observed in breast cancer and is associated with poor prognosis. One frequent type of aneuploidy, hypertetraploidy, may derive from ploidy duplication of hyperdiploid cells. However, the pathological consequences of ploidy duplication in breast cancer progression have not been characterized. Here, we present an experimental system demonstrating spontaneous appearance of hypertetraploid cells from organ-specific metastatic variants of the MDA-MB-231 breast cancer cell line through ploidy duplication in vitro and in vivo. The hypertetraploid progenies showed increased metastatic potential to lung and brain, but not to bone, which may be partially explained by the distinct capillary structures in these organs that confer differential lodging advantages to tumor cells with enlarged size. Our results suggest a potential mechanistic link between ploidy duplication and enhancement of metastatic potentials, as was observed in previous clinical studies of breast cancer.

Exosomal CD44 Cooperates with Integrin a6b4 to Support Organotropic Metastasis via Regulating Tumor Cell Motility and Target Host Cell Activation

Rapid metastasis to vital organs such as the lung,liver,and brain is responsible for the vast majority of pancreatic cancer deaths.Liver metastasis of pancreatic cancer accounts for the high mortality rate in patients.Exosomes derived from pancreatic cancer cells tend to be enriched in proteins that are anchored to the cell membrane,supporting the reprogramming of the tumor microenvironment and the progression of distant metastatic lesions.For the first time,our study has demonstrated that cluster of differentiation 44(CD44),a transmembrane glycoprotein delivered by exosomes,is involved in the metastatic process of pancreatic cancer.Moreover,CD44 was found to interact with integrin a6b4 to form a complex,thereby remodeling intracellular skeleton proteins,and to promote tumor cell motility through the activation of the Src and Ras signaling cascades.Notably,we also demonstrated that the CD44–a6b4 complex can be delivered to the target region via the paracrine effects of exosomes.The selective uptake of CD44-competent tumor exosomes by liver cells activated fibrotic pathways and generated a pre-metastatic niche by stimulating the cytokines,proinflammatory factors,and growth factors that ultimately support tumor metastasis.Our results suggest the potential application of exosomal CD44 as a biomarker for the clinical diagnosis of and therapy for pancreatic cancer.

Exposure of benzo[a]pyrene induces HCC exosome-circular RNA to activate lung fibroblasts and trigger organotropic metastasis

Background:Benzo[a]pyrene(B[a]P),a carcinogen pollutant produced by combustion processes,is present in the western diet with grilled meats.Chronic exposure of B[a]P in hepatocellular carcinoma(HCC)cells promotes metastasis rather than primary proliferation,implying an unknown mechanism of B[a]P-induced malignancy.Given that exosomes carry bioactive molecules to distant sites,we investigated whether and how exosomes mediate cancer-stroma communications for a toxicologically associated microenvironment.Method:Exosomes were isolated from B[a]P stimulated BEL7404 HCC cells(7404-100Bap Exo)at an environmental relevant dose(100 nmol/L).Lung preeducation animal model was prepared via injection of exosomes and cytokines.The inflammatory genes of educated lungs were evaluated using quantitative reverse transcription PCR array.HCC LM3 cells transfected with firefly luciferase were next injected to monitor tumor burdens and organotropic metastasis.Profile of B[a]P-exposed exosomes were determined by ceRNA microarray.Interactions between circular RNA(circRNA)and microRNAs(miRNAs)were detected using RNA pull-down in target lung fibroblasts.Fluorescence in situ hybridization and RNA immunoprecipitation assay was used to evaluate the“on-off”interaction of circRNA-miRNA pairs.We further developed an adenoassociated virus inhalation model to examine mRNA expression specific in lung,thereby exploring the mRNA targets of B[a]P induced circRNA-miRNA cascade.Results:Lung fibroblasts exert activation phenotypes,including focal adhesion and motility were altered by 7404-100Bap Exo.In the exosome-educated in vivo model,fibrosis factors and pro-inflammatory molecules of are up-regulated when injected with exosomes.Compared to non-exposed 7404 cells,circ_0011496 was up-regulated following B[a]P treatment and wasmainly packaged into 7404-100Bap Exo.Exosomal circ_0011496 were delivered and competitively bound to miR-486-5p in recipient fibroblasts.The down-regulation of miR-486-5p converted fibroblast to cancer-associated fibroblast via regulating the downstream of Twinfilin-1(TWF1)and matrix metalloproteinase-9(MMP9)cascade.Additionally,increased TWF1,specifically in exosomal circ_0011496 educated lungs,could promote cancer-stroma crosstalk via activating vascular endothelial growth factor(VEGF).These modulated fibroblasts promoted endothelial cells angiogenesis and recruited primary HCC cells invasion,as a consequence of a pre-metastatic niche formation.Conclusion:We demonstrated that B[a]P-induced tumor exosomes can deliver circ_0011496 to activate miR-486-5p/TWF1/MMP9 cascade in the lung fibroblasts,generating a feedback loop that promoted HCC metastasis.