engleski

FOCAL ADHESION KINASE IS NOT INVOLVED IN CISPLATIN RESISTANCE OF A HUMAN LARYNGEAL CARCINOMA CELL LINE EXPRESSING α vβ 3 INTEGRIN

Integrins are the main receptors for extracellular matrix proteins and have a function to transmit signals into the cytoplasm. A number of important biological processes, including cell survival, are controlled by integrin-dependent signals. Ligand binding to the extracellular integrin domain induces conformational changes and integrin clustering for activation of signaling cascades and recruitment of multiprotein complexes to focal adhesions. The focal adhesion kinase (FAK) is one of major integrin associated proteins of an integrin-dependent signaling pathway. We have previously showed the appearance of resistance to several anti-cancer drugs (cisplatin, mitomycin C and doxorubicin) on the model of human laryngeal carcinoma (HEp2)-α vβ 3 integrin expressing stable transfectants, and concluded that multidrug resistance is the consequence of glutathione dependent increased ability of α vβ 3 expressing cells to eliminate drug induced ROS. The goal of this research was to examine whether the expression of the dominant negative FAK inhibitor FAK-related non-kinase (FRNK), by adenoviral vector containing FRNK (Ad5gfpFRNK), will result in abrogation of cisplatin resistance. A virus lacking FRNK (Ad5gfp) was used as a control. Both types of viruses were multiplied in human embryonic kidney cell line-293 cell culture and purified by bending in CsCl gradients. When HEp2 and HEp2-α vβ 3 integrin expressing cell clone K1 (HEp2-K1) were transduced with Ad5gfpFRNK we observed a decrease in autophosphorylation of FAK in both cell lines, coincident with a large increase in FRNK expression. The transduction of HEp2 and HEp2-K1 cells with control Ad5gfp didn’ t change FAK autophosphorylation. We measured the sensitivity of HEp2 and HEp2-K1 cells transduced with Ad5gfpFRNK and Ad5gfp to cisplatin and show that expression of FRNK from adenovirus vector didn’ t sensitize HEp2-K1 cells to cisplatin. We conclude that FAK is not involved in the intracellular mechanism leading to resistance of α vβ 3 integrin expressing HEp2-K1 cells to cisplatin. Further investigations are currently underway in our lab to identify the exact signal pathway in α vβ 3-mediated drug resistance.

focal adhesion kinase; resistance; integrin α vβ 3; cisplatin

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