Using a model of the human SK-Mel-147 melanoma cell line, it was shown that blocking the expression of integrin α3β1 by transduction of cells with α3-specific shRNA did not affect their proliferation, but sharply increased the proportion of SA-β-Gal-positive cells, a phenotypic feature of cell senescence. These findings were accompanied by a significant increase in the activity of the Akt and mTOR protein kinases and the expression of p53 and p21 oncosupressors. Pharmacological inhibition of mTORC1 reduced the number SA-β-Gal-positive cells in the SK-Mel-147 cell population depleted of α3β1. Based on our recent data on a non-canonical function of Akt isomers in the regulation of SK-Mel-147 cell senescence caused by deficiency of α2β1 receptor, we investigated the role of Akt isomers in senescence induced by the α3β1 knockdown. It appeared that in the cell population with downregulated α3β1, inhibition of Akt1 reduced the number SA-β-Gal positive cells to the level of control cell population, while inhibition of Akt2 had no visible effect. Our results demonstrate that the laminin-specific integrin α3β1, like the collagen-specific receptor α2β1, is involved in tumor cell protection from senescence, and senescence induced by α3β1 depletion, like that caused by α2β1 deficiency, is based on a signaling mechanism employing a non-canonical function of the Akt1 isoform.
Na kletkakh linii SK-Mel-147 melanomy cheloveka pokazano, chto blokirovanie ékspressii integrina α3β1 putem transduktsii kletok α3-spetsificheskoĭ shRNA ne vliialo na ikh proliferatsiiu, no rezko uvelichivalo soderzhanie SA-β-Gal-polozhitel'nykh kletok — fenotipicheskogo priznaka kletochnogo stareniia. Éti izmeneniia soprovozhdalis' sushchestvennym uvelicheniem aktivnosti proteinkinaz Akt i mTOR i ékspressii onkosupressorov p53 i p21. Farmakologicheskoe ingibirovanie mTORC1 snizhalo soderzhanie SA-β-Gal polozhitel'nykh kletok v populiatsii SK-Mel-147 kletok, defitsitnykh po α3β1. Osnovyvaias' na ranee poluchennykh nami dannykh o nekanonicheskoĭ funktsii izomerov Akt v regulirovanii stareniia kletok SK-Mel-147, vyzvannogo defitsitom integrina α2β1, issledovali rol' Akt izomerov v starenii, indutsirovannom supressieĭ α3β1. Okazalos', chto v kletochnoĭ populiatsii s blokirovannoĭ ékspressieĭ étogo retseptora ingibirovanie Akt1 snizhaet soderzhanie SA-β-Gal polozhitel'nykh kletok do urovnia kontrol'noĭ populiatsii, v to vremia kak ingibirovanie Akt2 ne imelo zametnogo éffekta. Poluchennye dannye demonstriruiut, chto: (i) laminin-spetsificheskiĭ integrin α3β1, kak i kollagen-spetsificheskiĭ retseptor α2β1, uchastvuet v zashchite opukholevykh kletok ot stareniia, (ii) v osnove stareniia, indutsirovannogo supressieĭ α3β1, takzhe lezhit signal'nyĭ mekhanizm, v kotorom Akt1 vypolniaet nekanonicheskuiu funktsiiu.
Keywords: cellular senescence; integrins; non-canonic function of Akt protein kinase; signaling; tumor progression.