Background: Ovarian cancer (OC) is the second most frequent gynecological cancer and is associated with a poor prognosis because OC progression is often asymptoma-tic and is detected at a late stage. There remains an urgent need for novel targeted therapies to improve clinical outcomes in ovarian cancer. As a nitric oxide prodrug, JS-K is reported highly cytotoxic to human cancer cells such as acute myeloid leukemia, multiple myeloma and breast cancer. This study is aim to investigate the influence of JS-K on proliferation and apoptosis in ovarian cancer cells and explored possible autophagy-related mechanisms, which will contribute to future ovarian cancer therapy and supply theory support that JS-K holds great promise as a novel therapeutic agent against ovarian cancer.
Methods: The cytotoxicity, extracellular ROS/RNS activity and apoptotic effect of JS-K and indicated inhibitors on ovarian cancer cells in vitro were evaluated by MTT assay, extracellular ROS/RNS assay, caspases activities assay and western blot. Further autophagy effect of JS-K and indicated inhibitors were examined by MTT assay, cell transfection, immunofluorescence analysis, transmission electron microscopy (TEM) analysis and western blot on ovarian cancer cells in vitro. In vivo, the BALB/c-nude female mice with SKOV3 ovarian cancer cells xenograft were used to examine the efficacy of JS-K treatment on tumor growth. PCNA and p62 proteins were analyzed by immunohistochemistry.
Results: In vitro, JS-K inhibited the proliferation of ovarian cancer cells, induced apoptosis and cell nucleus shrinkage, enhanced the enzymatic activity of caspase-3/7/8/9, and significantly increased the production of ROS/RNS in ovarian cancer A2780 and SKOV3 cells, these effects were attenuated by inhibition of NAC. In addition, JS-K induced autophagy-related proteins and autophagosomes changes in ovarian cancer A2780 and SKOV3 cells. In vivo, JS-K inhibited tumor growth, decreased p62 protein expression and increased the expression levels of PCNA in xenograft models which were established using SKOV3 ovarian cancer cells.
Conclusion: Taken together, we demonstrated that ROS/RNS stress-mediated apoptosis and autophagy are mechanisms by which SKOV3 cells undergo cell death after treatment with JS-K in vitro. Moreover, JS-K inhibited SKOV3 tumor growth in vivo. An alternative therapeutic approach for triggering cell death in cancer cells could constitute a useful multimodal therapies for treating ovarian cancer, which is known for its resistance to apoptosis-inducing drugs.
Keywords: Apoptosis; Autophagy; JS-K; Ovarian cancer; Reactive oxygen species (ROS).