Ergosterol peroxide from marine fungus Phoma sp. induces ROS-dependent apoptosis and autophagy in human lung adenocarcinoma cells

Han-Ying Wu,Tz-Chuen Ju,Feng-Ling Yang,Kuo-Feng Hua,Michael V. Pivkin,Chih-Yu Hsieh,Lan-Hui Li,Wei-Ting Wong,Shih-Hsiung Wu,Yerra Koteswara Rao

doi:10.1038/s41598-018-36411-2

Abstract

As part of our ongoing search for novel therapeutic structures from microorganism, the chemical examination of marine fungus Phoma sp. resulted in the isolation of ergosterol, ergosterol peroxide (EP), and 9,11-dehydroergosterol peroxide (DEP). The bioassay results demonstrated that the three isolates reduced the viability of various cancer cells, with EP being highest in human lung cancer cell line A549 cells. EP induced caspase-dependent apoptosis through mitochondrial damage in A549 cells. Additionally, EP-induced ROS generation and apoptosis were attenuated by ROS-generating enzymes inhibitors and antioxidant N-acetylcysteine, indicated that ROS played an important role in EP-mediated apoptosis in A549 cells. Furthermore, it was observed that EP induced ROS-dependent autophagy, which attenuated apoptosis in A549 cells. On the other hand, EP reduced the LPS/ATP-induced proliferation and migration of A549 cells through attenuated NLRP3 inflammasome activity. Additionally, EP showed synergistic cytotoxic effect with antitumor drug Sorafenib in A549 cell viability inhibition. Furthermore, Micro-Western Array and Western blot analyses demonstrated that the protein levels of EGFR, HSP27, MEK5, AKT1, mTOR, Smad2, Smad3, TAB1, NF-κB, and HIF1-α decreased, while the levels of p-p38α, p-ERK1/2, p-JNK, fibronectin and p27 increased. Collectively, the results of this study demonstrated that EP might be useful to develop a therapeutic candidate for lung cancer complications.

Highlights

The incidence of cancer is the most serious health issues of the 21st century, with lung cancer being the leading cause of cancer-related deaths throughout the globe
Our results showed that ergosterol and dehydroergosterol peroxide (DEP) were nontoxic to normal lung cells Beas-2b, as well as macrophages RAW 264.7, while ergosterol peroxide (EP) showed less sensitive (i.e., IC50 values 174 and 222 μM, respectively) (Table 1)
These results pointed that the tested compounds ergosterol, EP and DEP were more sensitive to cancer cells, while less sensitive or nontoxic to normal cells

Summary

Introduction

The incidence of cancer is the most serious health issues of the 21st century, with lung cancer being the leading cause of cancer-related deaths throughout the globe. The major lung cancer NSCLC includes various types such as squamous cell carcinoma, large cell carcinoma, adenocarcinoma, pleomorphic, carcinoid tumor, and salivary gland carcinoma[1]. Generation of reactive oxygen species (ROS) conventionally regarded as cytotoxic and apoptosis inducers in cancer cells[10]. In cancer cells autophagy may play a role as both a tumor suppressor and a cell survival inducer. Inflammation is defense mechanism in living organism, persistent and chronic inflammation play an important role in cancer development including lung cancer[13]. The isolated metabolites examined for their cytotoxic potential in different cancer types as well as normal cells. The potential cytotoxic agent EP against A549 cells further evaluated for its ability to induce apoptosis, autophagy, ROS generation, and to attenuate the elevated NLRP3 inflammasome in A549 cells

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