Abstract 4240: Targeting Galectin-3 to reverse tumor stemness and drug resistance

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA We have recently linked integrin αvβ3 expression to metastatic potential, stemness, and therapy resistance due to its capacity to couple to KRAS. This leads to the induction of RalB/TBK-1 and the activation of NFκB to shift tumor cells to a stem-like phenotype. To understand how integrin αvβ3 couples to KRAS, we generated β3 domain swap mutants containing either the intracellular or extracellular domains of β1 integrin. Each chimera partially reduced KRAS association with αvβ3, suggesting interactions on each side of the plasma membrane may contribute. Since the short β3 cytoplasmic tail has no putative KRAS binding regions, we considered Galectin-3 as a putative scaffolding partner to facilitate the αvβ3/KRAS association due to its reported binding to both KRAS and integrins. Indeed, treating cells with GCS-100, a complex polysaccharide that has the ability to bind to and block the effects of Galectin-3, decreased Galectin-3 surface expression, αvβ3 clustering, and αvβ3/KRAS association. Exposing cells to this drug also decreased tumor stem properties. Our observations provide a molecular basis for the αvβ3/KRAS/Galectin-3 complex and highlight the potential for Galectin-3 blockade as a therapeutic approach to reverse the aggressive behavior of αvβ3-expressing tumors. Citation Format: Shumei Kato, Laetitia Seguin, Aleksandra Franovic, Hisashi Kato, Maria Camargo, Jay Desgrosellier, Sudarshan Anand, Sara Weis, Sanford Shattil, David A. Cheresh. Targeting Galectin-3 to reverse tumor stemness and drug resistance. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4240. doi:10.1158/1538-7445.AM2014-4240