RESUMEN
EML4-ALK fusion, observed in about 3%-7% of human lung adenocarcinoma, is one of the most important oncogenic drivers in initiating lung tumorigenesis. However, it still remains largely unknown about how EML4-ALK fusion exactly fires downstream signaling and drives lung cancer formation. We here find that EML4-ALK variant 1 (exon 1-13 of EML4 fused to exon 20-29 of ALK) forms condensates via phase separation in the cytoplasm of various human cancer cell lines. Using two genetically engineered mouse models (GEMMs), we find that EML4-ALK variant 1 can drive lung tumorigenesis and these murine tumors, as well as primary tumor-derived organoids, clearly show the condensates of EML4-ALK protein, further supporting the findings from in vitro study. Mutation of multiple aromatic residues in EML4 region significantly impairs the phase separation of EML4-ALK and dampens the activation of the downstream signaling pathways, especially the STAT3 phosphorylation. Importantly, it also significantly decreases cancer malignant transformation and tumor formation. These data together highlight an important role of phase separation in orchestrating EML4-ALK signaling and promoting tumorigenesis, which might provide new clues for the development of clinical therapeutic strategies in treating lung cancer patients with the EML4-ALK fusion.
RESUMEN
Dermal fibroblasts are a promising candidate for cellular-based therapies for thermal wound healing because of their capacity of producing extracellular matrix (ECM), promoting wound contraction and the synthesis of type I collagen, and secreting growth factors. miRNAs (MicroRNAs) might mediate the role of TGF-ß1(Transforming Growth Factor-beta 1), one of the major profibrotic cytokines, in improving thermal injury repair. In the present study, we observed the abnormal downregulation of TGF-ß1 following thermal injury in the burnt dermis (in vivo) and heat-stimulated human dermal fibroblasts (in vitro). TGF-ß1 overexpression reversed heat stimulation-induced repression on fibroblast viability, migration, and ECM synthesis. As demonstrated by online tool prediction and experimental analysis, miR-506-3p downregulated TGF-ß1 levels via directly targeting TGFB1. In heat-stimulated human dermal fibroblasts, miR-506-3p expression showed to be significantly upregulated. miR-506-3p inhibition also reversed heat stimulation-induced repression on fibroblast viability, migration, and ECM synthesis; more importantly, TGF-ß1 silencing aggravated the thermal injury in vitro and significantly reversed the effects of miR-506-3p inhibition on heat-stimulated dermal fibroblasts. In conclusion, miR-506-3p and its downstream target TGF-ß1 form a regulatory axis, modulating the cell viability, migration, and ECM synthesis in human dermal fibroblasts following burn injury.
