Withaferin-A induced vimentin S56 phosphorylation dissociates NEDD9 signaling loop to regress progressive metastatic melanoma into lung adenocarcinoma.

Metastasis is complex and insidious type of disease involves multiple signaling nexus, which have implications in understanding disease pathogenesis. Treatment failure for metastatic cancer is frequently high due to aggressive adaptation of cancerous cells to invade to neighboring organs. Cytoskeleton intermediate filamentous protein Vimentin and scaffolding protein Neural precursor cell expressed Developmentally Down-regulated protein 9 (NEDD9) play a key role in metastatic events by regulating multiple metastatic events. Interaction between these proteins is necessary to promote metastatic progression. Withaferin A (WFA), a natural pharamacophore, known to target Vimentin to induce antitumor potential. However exact molecular mechanism still yet to be elucidated. We hypothesize, Vimentin-NEDD9 signaling nexus is necessary for metastatic progression and targeting this interwoven signaling loop with effective pharamacophore WFA halts metastatic progression of melanoma into lung. To elucidate the same, we carried out gene expression measurement through quantitative Reverses Transcription Polymerase Chain Reaction (qRT-PCR), Immunoblot and Immunohistochemistry. Assessment of interactive signaling by Co-immunoprecipitation, Immunofluorescence, Co-localization and Proximity ligation assay. Phosphorylation studies through transfection of phospho specific mutant constructs generated through site directed mutagenesis. WFA induced cellular behavioral changes by migration, invasion assays and Immunoblot analysis. The B16F10 induced mouse metastatic melanoma model to asses NEDD9-Vimentin expression and anti-metastasis induced by WFA. The results postulates, elevated levels and interaction between NEDD9-Vimentin proteins, have positive correlation in metastatic progression of melanoma into lung in both in-vitro and in-vivo condition, establishing it as therapeutic target. Pharmacologically, WFA targets this complex by extending its activity by not only inducing specific Serine 56 phosphorylation of Vimentin, also dissociates NEDD9 signaling loop to halt Epithelial-mesenchymal transition (EMT) and subsequent metastatic events. Eventually, modulation of the relevant metastatic genes E-Cadherin, N-Cadherin, SNAIL, MMP-2 & MMP-9 resulted in regression of metastatic melanoma progression to lung. The study validates WFA induced S56 phosphorylation is necessary to abrupt the NEDD9-Vimentin metastatic signaling complex to regress aggressive metastatic melanoma. The investigation emphasized more mechanistic approach of WFA. Understanding and targeting such integrative mechanical input in the tumor microenvironment will be a better therapeutic strategy to combat metastasis.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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