Tetraspanin 8 is a novel regulator of ILK-driven β1 integrin adhesion and signaling in invasive melanoma cells. El Kharbili, M., Robert, C., Witkowski, T., Danty-Berger, E., Barbollat-Boutrand, L., Masse, I., Gadot, N., de la Fouchardière, A., McDonald, P. C., Dedhar, S., Le Naour, F., Degoul, F., & Berthier-Vergnes, O. Oncotarget, February, 2017.
doi  abstract   bibtex   
Melanoma is well known for its propensity for lethal metastasis and resistance to most current therapies. Tumor progression and drug resistance depend to a large extent on the interplay between tumor cells and the surrounding matrix. We previously identified Tetraspanin 8 (Tspan8) as a critical mediator of melanoma invasion, whose expression is absent in healthy skin. The present study investigated whether Tspan8 may influence cell-matrix anchorage and regulate downstream molecular pathways leading to an aggressive behavior. Using silencing and ectopic expression strategies, we showed that Tspan8-mediated invasion of melanoma cells resulted from defects in cell-matrix anchorage by interacting with β1 integrins and by interfering with their clustering, without affecting their surface or global expression levels. These effects were associated with impaired phosphorylation of integrin-linked kinase (ILK) and its downstream target Akt-S473, but not FAK. Specific blockade of Akt or ILK activity strongly affected cell-matrix adhesion. Moreover, expression of a dominant-negative form of ILK reduced β1 integrin clustering and cell-matrix adhesion. Finally, we observed a tumor-promoting effect of Tspan8 in vivo and a mutually exclusive expression pattern between Tspan8 and phosphorylated ILK in melanoma xenografts and human melanocytic lesions. Altogether, the in vitro, in vivo and in situ data highlight a novel regulatory role for Tspan8 in melanoma progression by modulating cell-matrix interactions through β1 integrin-ILK axis and establish Tspan8 as a negative regulator of ILK activity. These findings emphasize the importance of targeting Tspan8 as a means of switching from low- to firm-adhesive states, mandatory to prevent tumor dissemination.
@article{el_kharbili_tetraspanin_2017,
	title = {Tetraspanin 8 is a novel regulator of {ILK}-driven β1 integrin adhesion and signaling in invasive melanoma cells},
	issn = {1949-2553},
	doi = {10.18632/oncotarget.15084},
	abstract = {Melanoma is well known for its propensity for lethal metastasis and resistance to most current therapies. Tumor progression and drug resistance depend to a large extent on the interplay between tumor cells and the surrounding matrix. We previously identified Tetraspanin 8 (Tspan8) as a critical mediator of melanoma invasion, whose expression is absent in healthy skin. The present study investigated whether Tspan8 may influence cell-matrix anchorage and regulate downstream molecular pathways leading to an aggressive behavior. Using silencing and ectopic expression strategies, we showed that Tspan8-mediated invasion of melanoma cells resulted from defects in cell-matrix anchorage by interacting with β1 integrins and by interfering with their clustering, without affecting their surface or global expression levels. These effects were associated with impaired phosphorylation of integrin-linked kinase (ILK) and its downstream target Akt-S473, but not FAK. Specific blockade of Akt or ILK activity strongly affected cell-matrix adhesion. Moreover, expression of a dominant-negative form of ILK reduced β1 integrin clustering and cell-matrix adhesion. Finally, we observed a tumor-promoting effect of Tspan8 in vivo and a mutually exclusive expression pattern between Tspan8 and phosphorylated ILK in melanoma xenografts and human melanocytic lesions. Altogether, the in vitro, in vivo and in situ data highlight a novel regulatory role for Tspan8 in melanoma progression by modulating cell-matrix interactions through β1 integrin-ILK axis and establish Tspan8 as a negative regulator of ILK activity. These findings emphasize the importance of targeting Tspan8 as a means of switching from low- to firm-adhesive states, mandatory to prevent tumor dissemination.},
	language = {eng},
	journal = {Oncotarget},
	author = {El Kharbili, Manale and Robert, Clément and Witkowski, Tiffany and Danty-Berger, Emmanuelle and Barbollat-Boutrand, Laetitia and Masse, Ingrid and Gadot, Nicolas and de la Fouchardière, Arnaud and McDonald, Paul C. and Dedhar, Shoukat and Le Naour, François and Degoul, Françoise and Berthier-Vergnes, Odile},
	month = feb,
	year = {2017},
	pmid = {28188308},
	keywords = {ILK, integrin, matrix, melanoma, tetraspanin 8},
}

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