Pardaxin Activates Excessive Mitophagy and Mitochondria-Mediated Apoptosis in Human Ovarian Cancer by Inducing Reactive Oxygen Species.

Yen-Po Chen,You-Hsien Lin,Zhi-Hong Wen,Chien-Wei Feng,Chang-Cheng Wu,Hsiao-Mei Kuo,Kuan-Hao Tsui,Po-Chang Shih

doi:10.3390/antiox10121883

Abstract

Most ovarian cancer (OC) patients are diagnosed with stage III or higher disease, resulting in a poor prognosis. Currently, paclitaxel combined with carboplatin shows the best treatment outcome for OC. However, no effective drug is available for patients that do not respond to treatment; thus, new drugs for OC are needed. We evaluated the antimicrobial peptide, pardaxin, in PA-1 and SKOV3 cells. Pardaxin induced apoptosis as determined by MTT and TUNEL assays, as well as activation of caspases-9/3, Bid, t-Bid, and Bax, whereas Bcl-2 was downregulated. The IC50 values for pardaxin were 4.6–3.0 μM at 24 and 48 h. Mitochondrial and intracellular reactive oxygen species (ROS) were overproduced and associated with disrupted mitochondrial membrane potential and respiratory capacity. Additionally, the mitochondrial network was fragmented with downregulated fusogenic proteins, MFN1/2 and L-/S-OPA1, and upregulated fission-related proteins, DRP1 and FIS1. Autophagy was also activated as evidenced by increased expression of autophagosome formation-related proteins, Beclin, p62, and LC3. Enhanced mitochondrial fragmentation and autophagy indicate that mitophagy was activated. ROS-induced cytotoxicity was reversed by the addition of N-acetylcysteine, confirming ROS overproduction as a contributor. Taken together, pardaxin demonstrated promising anticancer activity in OC cells, which warrants further preclinical development of this compound.

Highlights

Ovarian cancer (OC) is the fifth leading cause of cancer-related deaths in females [1]with over 22,000 new cases each year and 14,000 deaths occurring [2], with the epithelial type ovarian cancer (OC) being the most common [3]
The results indicated that the ratios of JC-1 aggregates/monomers were decreased to 1.2 ± 0.1 and 2.8 ± 0.8% at 5 μM pardaxin in PA-1 and SKOV3 cells, respectively, compared with the controls (14.4 ± 3.8 and 19.4 ± 4.9%)
~5.0-fold, and ~0.7-fold, respectively, relative to untreated cells (Figure 2I). These results indicated that pardaxin enhances cellular and Mitochondrial ROS (mtROS), and induces apoptosis through Bcl-2 family members in PA-1 and SKOV3 cells, while disrupting the mitochondrial membrane potential

Summary

Introduction

With over 22,000 new cases each year and 14,000 deaths occurring [2], with the epithelial type OC being the most common [3]. Despite a high response rate, tumors eventually develop resistance and are refractory to further treatment. ROS include superoxide anion radicals (O2 − ), hydroxyl radicals ( OH), hydrogen peroxide (H2 O2 ), and singlet oxygen [7]. Mitochondria are the primary site of ROS generation because of their respiratory and energy production cascade. To prevent cellular damage and apoptosis caused by ROS, cells contain antioxidant enzymes, such as superoxide dismutases, to detoxify ROS [9,10]. The generation of ROS has been studied as a treatment for cancer [11]

Methods

Results

Conclusion