BackgroundNeuropilin-1 (NRP-1), a non-tyrosine kinase glycoprotein receptor, is associated with poor prognosis breast cancer, however transcriptomic changes triggered by NRP-1 overexpression and its association with chemoresistance in breast cancer have not yet been explored.MethodsBT-474 NRP-1 variant cells were generated by stable overexpression of NRP-1 in the BT-474 breast cancer cell line. RNA sequencing and qRT-PCR were conducted to identify differentially expressed genes. The role of an upregulated oncogene, Tenascin C (TNC) and its associated pathway was investigated by siRNA-mediated knockdown. Resistant variants of the control and BT-474 NRP-1 cells were generated by sequential treatment with four cycles of Adriamycin/Cyclophosphamide (4xAC) followed by four cycles of Paclitaxel (4xAC + 4xPAC).ResultsNRP-1 overexpression increased cellular tumorigenic behavior. RNA sequencing identified upregulation of an oncogene, Tenascin-C (TNC) and downregulation of several tumor suppressors in BT-474 NRP-1 cells. Additionally, protein analysis indicated activation of the TNC-associated integrin β3 (ITGB3) pathway via focal adhesion kinase (FAK), Akt (Ser473) and nuclear factor kappa B (NF-kB) p65. siRNA-mediated TNC knockdown ablated the migratory capacity of BT-474 NRP-1 cells and inactivated FAK/Akt473 signaling. NRP-1 overexpressing cells downregulated breast cancer resistance protein (BCRP/ABCG2). Consequently, sequential treatment with Adriamycin/Cyclophosphamide (AC) cytotoxic drugs to generate resistant cells indicated that BT-474 NRP-1 cells increased sensitivity to treatment by inactivating NRP-1/ITGB3/FAK/Akt/NF-kB p65 signaling compared to wild-type BT-474 resistant cells.ConclusionsWe thus report a novel mechanism correlating high baseline NRP-1 with upregulated TNC/ITGB3 signaling, but decreased ABCG2 expression, which sensitizes BT-474 NRP-1 cells to Adriamycin/Cyclophosphamide. The study emphasizes on the targetability of the NRP-1/ITGB3 axis and its potential as a predictive biomarker for chemotherapy response.Electronic supplementary materialThe online version of this article (10.1186/s12885-018-4446-y) contains supplementary material, which is available to authorized users.

New compounds are needed to overcome the resistance to commonly used cytotoxic chemotherapy for epithelial ovarian cancer. Marine sponges are a rich source of diverse chemical compounds, and hymenialdisine has been found to have antiproliferative effects. We investigated the cytotoxic effect of hymenialdisine in cisplatin-sensitive and cisplatin-resistant ovarian cancer cell lines. Methods: The anti-cancer effects of hymenialdisine or cisplatin were assessed by treating cells with different concentrations of hymenialdisine and cisplatin. Cell viability was determined using the AlamarBlue® Assay. Results: The IC50 of cisplatin was estimated at 31.4 μM for A2780S and 76.9 μM for A2780CP, whereas the IC50 of hymenialdisine was evaluated at 146.8 μM for A2780S cells. Despite the higher concentrations of hymenialdisine (up to 300 μM), IC50 could not be determined for the A2780CP cell line. Conclusion: When compared to cisplatin, hymenialdisine was less toxic against both A2780S and A2780CP ovarian cancer cell lines. Keywords: Ovarian Cancer, Marine compounds, Cisplatin, Hymenialdisine, Oman

High-grade epithelial ovarian cancer is a fatal disease in women frequently associated with drug resistance and poor outcomes. We previously demonstrated that a marine-derived compound MalforminA1 (MA1) was cytotoxic for the breast cancer cell line MCF-7. In this study, we aimed to examine the effect of MA1 on human ovarian cancer cells. The potential cytotoxicity of MA1was tested on cisplatin-sensitive (A2780S) and cisplatin-resistant (A2780CP) ovarian cancer cell lines using AlamarBlue assay, Hoechst dye, flow cytometry, Western blot, and RT-qPCR. MA1 had higher cytotoxic activity on A2780S (IC50 = 0.23 µM) and A2780CP (IC50 = 0.34 µM) cell lines when compared to cisplatin (IC50 = 31.4 µM and 76.9 µM, respectively). Flow cytometry analysis confirmed the cytotoxic effect of MA1. The synergistic effect of the two drugs was obvious, since only 13% of A2780S and 7% of A2780CP cells remained alive after 24 h of treatment with both MA1 and cisplatin. Moreover, we examined the expression of bcl2, p53, caspase3/9 genes at RNA and protein levels using RT-qPCR and Western blot, respectively, to figure out the cell death mechanism induced by MA1. A significant down-regulation in bcl2 and p53 genes was observed in treated cells compared to non-treated cells (p < 0.05), suggesting that MA1 may not follow the canonical pathway to induce apoptosis in ovarian cancer cell lines. MalforminA1 showed promising anticancer activity by inducing cytotoxicity in cisplatin-sensitive and cisplatin-resistant cancer cell lines. Interestingly, a synergistic effect was observed when MA1 was combined with cisplatin, leading to it overcoming its resistance to cisplatin.

Objective: Ovarian cancer is one of the leading causes of cancer-related mortality in women, and is often associated with drug resistance. Therefore, finding effective drugs, including naturally derived compounds, is urgently needed. Herein, we aimed to test the anti-cancer potential of gallic acid monohydrate (GA) and its congeners on cisplatin-sensitive (A2780S), and resistant (A2780CP) ovarian cancer and normal ovarian (HOSE6-3) cell lines. Methods: Cytotoxicity was assessed by AlamarBlue and CCK08 assays by exposing cells to different concentrations of cisplatin (0-21µg/mL), GA and its congeners (0-100µg/mL), and a combination of GA and cisplatin. Apoptosis was estimated by Hoechst stain and monitoring the relative RNA expression of the apoptotic effector caspase-3 using qRT-PCR. Results: GA decreased cell viability in a concentration-dependent manner in all cell lines, with an IC 50 of 19.39µg/mL (A2780S), 35.59 µg/ mL (A2780CP), and 49.32µg/mL (HOSE6-3). GA displayed higher cytotoxicity than its congeners. An apoptotic rate estimation of approximately 20% and 30% was obtained in A2780S and A2780CP. While the cytotoxicity observed with cisplatin and GA was comparable, combining the two enhanced the cytotoxicity significantly, especially in the A2780CP cell line (p<0.05). Conclusion: These data suggest that GA may help overcome the resistance. Hence, the cytotoxic effects of GA, especially on chemo-resistant ovarian cancer cells merit further investigation.