We previously reported that miR-203 functions as a tumor suppressor in ovarian cancer cells by directly targeting transcription factor Snai2 and inhibiting epithelial to mesenchymal transition (EMT), whereas BIRC5/survivin promotes EMT. In this study, we tested our hypothesis that miR-203 inhibits ovarian tumor metastasis by suppressing EMT through targeting BIRC5, using an orthotopic ovarian cancer mouse model. We overexpressed miR-203 in ovarian cancer SKOV3 and OVCAR3 cells using a lentiviral vector and examined cell migration and invasion using transwell plates. The small molecule inhibitor, YM155, was used to inhibit survivin expression. miR-203-expressing and control SKOV3 cells were intrabursally injected into immunocompromised NSG female mice. Primary tumors in ovaries and metastatic tumors were collected to determine the expression of survivin and EMT markers using Western blot and immunostaining. Overexpression of miR-203 inhibits EMT by targeting BIRC5 in ovarian cancer SKOV3 and OVCAR3 cells. miR-203 expression enhances the ability of the survivin inhibitor YM155 to reduce tumor cell migration and invasion in vitro. We further showed that miR-203 expression attenuated the TGFβ pathway in both SKOV3 and OVCAR3 cells. miR-203 expression also inhibited primary tumor growth in ovaries and metastatic tumors in multiple peritoneal organs including liver and spleen. miR-203 inhibits ovarian tumor metastasis by targeting BIRC5/survivin and attenuating the TGFβ pathway.

Background: Multidrug resistance (MDR) is the main challenge of successful chemotherapy for ovarian cancer patients, with 50% to 75% of ovarian cancer patients eventually relapsed due to it. One of the effective strategies for treating MDR and improving therapeutic efficiency of ovarian cancer is to use nanotechnology-based targeted drug delivery systems. In this study, a novel nano targeted co-delivery system modified by hyaluronic acid (HA) was developed by using gold nanorods coated with functionalized mesoporous silica nanoparticles (HA-PTX/let-7a-GNR@MSN) for combined delivery of hydrophobic chemotherapy drug Paclitaxel (PTX) andlethal-7a(let-7a), a microRNA (miR), to overcome MDR in ovarian cancer. Furthermore, we also analyzed the molecular mechanism of this nanotherapeutic system in the treatment of ovarian cancer.Results: HA-modified nanocomplexes can specifically bind to the CD44 receptor, which is highly expressed in SKOV3/SKOV3_TRcells, achieving effective cell uptake and 150% enhancement of tumor site permeability. The nanosystem realized the stable combination and protective transportation of PTX and miRs. Analysis of drug-resistant SKOV3_TRcells and an SKOV3_TRxenograft model in BALB/c-nude mice showed significant downregulation of P-glycoprotein in heterogeneous tumor sites, PTX release, and subsequent induction of apoptosis. More importantly, this nanosystem could synergistically inhibit the growth of ovarian tumors. Further studies suggest that mTOR-mediated signaling pathways play an important role in reversing drug resistance and inducing apoptosis.Conclusions: To sum up, these data provide a model for overcoming PTX resistance in ovarian cancer.Graphical

Survivin, a member of the inhibitor of apoptosis family, is upregulated in multiple cancers including ovarian cancer, but is rarely detectable in normal tissues. We previously reported that survivin promoted epithelial-to-mesenchymal transition (EMT) in ovarian cancer cells, suggesting that survivin may contribute to ovarian tumor metastasis and chemoresistance. In this study, we tested whether knockout or pharmacologic inhibition of survivin overcomes chemoresistance and suppresses tumor metastasis. The genetic loss of survivin suppressed tumor metastasis in an orthotopic ovarian cancer mouse model. To pharmacologically test the role of survivin on ovarian tumor metastasis, we treated chemo-resistant ovarian cancer cells with a selective survivin inhibitor, MX106, and found that MX106 effectively overcame chemoresistance in vitro. MX106 inhibited cell migration and invasion by attenuating the TGFβ pathway and inhibiting EMT in ovarian cancer cells. To evaluate the efficacy of MX106 in inhibiting ovarian tumor metastasis, we treated an orthotopic ovarian cancer mouse model with MX106, and found that MX106 efficiently inhibited primary tumor growth in ovaries and metastasis in multiple peritoneal organs as compared with vehicle-treated control mice. Our data demonstrate that inhibition of survivin using either genetic knockout or a novel inhibitor MX106 suppresses primary ovarian tumor growth and metastasis, supporting that targeting survivin could be an effective therapeutic approach in ovarian cancer.

Background: Epithelial to mesenchymal transition (EMT) contributes to tumor metastasis and chemoresistance. Eukaryotic initiation factor 5A2 (EIF5A2) is highly expressed in a variety of human cancers but rarely expressed in normal tissues. While EIF5A2 has oncogenic activity in several cancers and contributes to tumor metastasis, its role in ovarian cancer is unknown. In this study, we investigate whether EIF5A2 contributes to ovarian tumor metastasis by promoting EMT.Methods: To investigate the role of EIF5A2, we knocked out (KO) EIF5A2 using lentiviral CRISPR/Cas9 nickase in high invasive SKOV3 and OVCAR8 cells and overexpressed EIF5A2 in low invasive OVCAR3 cells using lentiviral vector. Cell proliferation, migration and invasion was examined in vitro ovarian cancer cells and tumor metastasis was evaluated in vivo using orthotopic ovarian cancer mouse models.Results: Here we report that EIF5A2 is highly expressed in ovarian cancers and associated with patient poor survival. Lentiviral CRISPR/Cas9 nickase vector mediated knockout (KO) of EIF5A2 inhibits epithelial to mesenchymal transition (EMT) in SKOV3 and OVCAR8 ovarian cancer cells that express high levels of EIF5A2. In contrast, overexpression of EIF5A2 promotes EMT in OVCAR3 epithelial adenocarcinoma cells that express relatively low EIF5A2 levels. KO of EIF5A2 in SKOV3 and OVCAR8 cells inhibits ovarian cancer cell migration and invasion, while its overexpression promotes cell migration and invasion in OVCAR3 adenocarcinoma cells. We further demonstrate that EIF5A2 promotes EMT by activating the TGFβ pathway and KO of EIF5A2 inhibits ovarian tumor growth and metastasis in orthotopic ovarian cancer mouse models.Conclusion: Our results indicate that EIF5A2 is an important controller of ovarian tumor growth and metastasis by promoting EMT and activating the TGFβ pathway.

Active targeting co-delivery of therapeutic siRNAs and antineoplastic drugs is considered as a very promising approach to specifically improve the therapeutic effect by simultaneously inhibiting the expression of tumorigenic genes and reducing the systemic toxicity of anticancer drugs. This strategy for effectively targeting cancer stem cells (CSCs) has gained considerable attention in the therapeutic treatment of human cancers. The objective of this study was to fabricate and characterize the therapeutic survivin siRNAs (Sur siRNA) and anti-cancer drug doxorubicin (DOX)-loaded superparamagnetic iron oxide nanoparticles (SPIONPs) that are surface-conjugated to the specific ligand epidermal growth factor receptor (EGFR) which is highly expressed on brain glioblastoma stem cells (GSCs), using carboxymethyl chitosan (CMCS), polyethylenimine (PEI) and heparin-mediated cross linking agents. Our in vitro and in vivo studies demonstrated that the fabricated EGFR-targeted nanoparticles exhibited excellent targeting specificity and enhanced delivery efficiency, and could specifically co-deliver therapeutic siRNAs and DOX into GSCs, thus greatly improving the therapeutic efficacy by effectively silencing survivin gene expression and enhancing the treatment sensitivity of GSCs to anticancer drug DOX. Therefore, these fabricated EGFR-targeted nanoparticles would provide an efficient targeting vector for co-delivery of therapeutic siRNAs and anticancer drugs, and could be used as a promising active targeted nanocarrier for the selective treatment of human brain cancer in the future.