Toosendanin reduces cisplatin resistance in ovarian cancer through modulating the miR-195/ERK/β-catenin pathway

Cisplatin (DDP) resistance is prevalent in ovarian cancer (OC) patients and contributes to the poor prognosis. Therefore, it is of great significance to develop new agent to intervene and even reverse DDP resistance in OC. Toosendanin (TSN), a triterpenoid extracted from the bark or fruits of Melia toosendan Sieb et Zucc, has been proved to possess significant antitumor activities. However, the efficacy of TSN on DDP resistance in OC has not been reported yet.The aim of this study is to investigate the effects of TSN on DDP resistance in OC and explore the molecular mechanism in vitro and in vivo.Human OC cell line (SKOV3) and DDP-resistant cell line (SKOV3/DDP) were used. Cell proliferation was measured by CCK-8 and colony formation assay. Annexin V/PI double staining and hoechst 33342 nuclear staining were employed to detect cell apoptosis. Transwell and wound-healing assay were used to determine the invasion and migration potential of cells respectively. Quantitative real-time PCR (qPCR) and western blotting were performed to detect the expression of molecules related to miR-195/ERK/β-catenin pathway. The effects and mechanism of TSN on DDP resistance of OC in vivo was investigated using xenograft model, TUNEL staining assay and immunohistochemistry.TSN improved the DDP sensitivity of SKOV3/DDP cells in vitro and in vivo, reflected in promoting inhibition of proliferation, invasion, migration and epithelial mesenchymal transformation (EMT) as well as induction of apoptosis by DDP. TSN could modulate the miR-195/ERK/β-catenin axis by upregulating the miR-195-5p expression and then suppressing ERK/GSK3β/β-catenin pathway which were activated in SKOV3/DDP cells. Moreover, co-treatment of β-catenin pathway activator LiCl or miR-195-5p silencing partially recovered the DDP resistance which was previously repressed by TSN.Both in vitro and in vivo data demonstrated that TSN could reduce DDP resistance in OC through regulating the miR-195/ERK/β-catenin pathway, highlighting the potential of TSN as an effective agent for favoring overcoming clinical DDP resistance in OC.