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Overexpression of integrin αvβ3 in human laryngel carcinoma (Hep2) and tongue squamous carcinoma (Cal27) cells: adhesion, migration, invasion and resistance to antitumor drugs

Introduction Integrins play key roles in the regulation of tumor cell adhesion, migration, invasion and survival to antitumor drugs. The role of integrin αvβ3 warrants further exploration because of conflicting data obtained in different cell models. We have recently described, in human laryngeal carcinoma HEp2 cell line overexpressing integrin αvβ3, a novel mechanism of resistance to cisplatin, mitomycin C and doxorubicin, mediated by glutathione. In the present study we investigate whether similar mechanism exists in tongue squamous carcinoma Cal27 cells overexpressing integrin αvβ3. In addition we analyse cell adhesion, migration and invasion in both HEp2 and Cal27 cell models. Materials and methods We isolated integrin αvβ3 overexpressing cells from Cal27 cells by stable transfection of the plasmid containing β3 integrin subunit gene. The expression of integrins αvβ3 and αvβ5 and integrin subunit αv was determined by flow cytometry. The sensitivity of Cal27 and Cal27-derived integrin β3 stable transfectants to anticancer drugs was determined using MTT assay and plating efficiency assay. Boyden chambers were used to investigate migration and, when coated with matrigel, invasion. Adhesion was measured in plates previously coated with vitronectin or fibronectin. The in vivo sensitivity to cisplatin was assessed in nude mice. Results and discussion Cal27-derived integrin αvβ3 overexpressing cells are resistant to cisplatin, doxorubicin, mitomycin C, etoposide and camptothecin. The resistance mechanism was independent of glutathione. Both, HEp2 and Cal27 αvβ3 integrin overexpressing cell clones showed increased cell adhesion to vitronectin and fibronectin-coated plates as compared to parental cell lines. Cell migration toward serum, showed contradictory effect: integrin αvβ3-overexpression increase migration in HEp2 and decrease migration in Cal27 cell model. In Cal27 cell model the overexpression of integrin αvβ3 increased invasion in matrigel invasion chamber assay, while invasion experiments in HEp2 and HEp2 overexpressing integrin αvβ3 cells are in progress. Finally, using nude mice xenografted with HEp2 and HEp2 overexpressing integrin αvβ3 cells, we confirmed the in vivo resistance to cisplatin in HEp2 cells overexpressing integrin αvβ3. Conclusion Our observations emphasize the importance of developing new therapeutic approaches targeting integrin αvβ3 to circumvent tumor-resistance to drugs and to perhaps control metastatic potential.

integrin-mediated drug resistance

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