Galectin-3 induces ovarian cancer cell survival and chemoresistance via TLR4 signaling activation

Paclitaxel resistance becomes common in patients with aggressive ovarian cancer and results in recurrence after conventional therapy. Galectin-3 is a multifunctional lectin associated with cell migration, cell proliferation, cell adhesion, and cell-cell interaction in tumor cells. Whether circulating galectin-3 is involved in paclitaxel resistance in ovarian cancer remains unknown. The current study investigated the effect of galectin-3 on toll-like receptor 4 (TLR4) signaling and thus paclitaxel resistance. With blood and cancer tissue samples obtained from 102 patients, we identified associations between serum galectin-3 level or TLR4 expression and paclitaxel resistance phenotype. In vitro, treatment with exogenous galectin-3 restored cell survival and migration of SKOV-3 and ES-2 cells was decreased by galectin-3 silencing and paclitaxel treatment. Furthermore, exogenous galectin-3 boosted expression of TLR4, MyD88, and p-p65, as well as interleukin (IL)-6, IL-8, and vascular endothelial growth factor (VEGF) release induced by paclitaxel. Moreover, galectin-3 inhibited the interaction between TLR4 and caveolin-1 (Cav-1) in SKOV-3 and ES-2 cells. In addition, overexpression of Cav-1 dampened the expression of MyD88 and p-p65 stimulated by galectin-3 and enhanced apoptosis in SKOV-3 cells under paclitaxel exposure. In summary, our study elucidated that exogenous galectin-3 might induce paclitaxel resistance through TLR4 signaling activation by inhibiting TLR4-Cav-1 interaction, revealing a novel insight into paclitaxel resistance induction.