Poncirin Induces Apoptosis in AGS Human Gastric Cancer Cells through Extrinsic Apoptotic Pathway by up-Regulation of Fas Ligand.

Venu Saralamma,Suchismita Raha,Gyeong Hong,Silvia Yumnam,Sang Lee,Ho Lee,Won Lee,Eun Kim,Gon Kim,Jeong Heo,Arulkumar Nagappan

doi:10.3390/ijms160922676

Abstract

Poncirin, a natural bitter flavanone glycoside abundantly present in many species of citrus fruits, has various biological benefits such as anti-oxidant, anti-microbial, anti-inflammatory and anti-cancer activities. The anti-cancer mechanism of Poncirin remains elusive to date. In this study, we investigated the anti-cancer effects of Poncirin in AGS human gastric cancer cells (gastric adenocarcinoma). The results revealed that Poncirin could inhibit the proliferation of AGS cells in a dose-dependent manner. It was observed Poncirin induced accumulation of sub-G1 DNA content, apoptotic cell population, apoptotic bodies, chromatin condensation, and DNA fragmentation in a dose-dependent manner in AGS cells. The expression of Fas Ligand (FasL) protein was up-regulated dose dependently in Poncirin-treated AGS cells Moreover, Poncirin in AGS cells induced activation of Caspase-8 and -3, and subsequent cleavage of poly(ADP-ribose) polymerase (PARP). Inhibitor studies’ results confirm that the induction of caspase-dependent apoptotic cell death in Poncirin-treated AGS cells was led by the Fas death receptor. Interestingly, Poncirin did not show any effect on mitochondrial membrane potential (ΔΨm), pro-apoptotic proteins (Bax and Bak) and anti-apoptotic protein (Bcl-xL) in AGS-treated cells followed by no activation in the mitochondrial apoptotic protein caspase-9. This result suggests that the mitochondrial-mediated pathway is not involved in Poncirin-induced cell death in gastric cancer. These findings suggest that Poncirin has a potential anti-cancer effect via extrinsic pathway-mediated apoptosis, possibly making it a strong therapeutic agent for human gastric cancer.

Highlights

Gastric cancer is the second leading cause of cancer-related deaths; the incidence rates for gastric cancer are high in Asian countries such as Korea, China and Japan [1]
To determine appropriate inhibitory concentrations of Poncirin on AGS cells, cells were treated with various concentrations (50, 100, 150 and 200 μM) of Poncirin for 24 h and the cell viability was measured by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay
It was observed that Poncirin treated AGS cells did not alter the mitochondrial membrane potential (ΔΨm) activity in both a time and dose dependent manner (Figure 6A). These results suggest that mitochondrial intrinsic apoptotic pathway was not involved in Poncirin-induced apoptosis in AGS cells

Summary

Introduction

Gastric cancer is the second leading cause of cancer-related deaths; the incidence rates for gastric cancer are high in Asian countries such as Korea, China and Japan [1]. Even though survival rates of gastric cancer patients are increasing gradually with advanced techniques, most of the patients die at a late severe stage [2,3]. Gastric cases in the elderly population are increasing in number as they cannot tolerate conventional chemotherapy [4]. The available treatments for gastric cancer are inadequate. With the recent advanced techniques, the overall give-year survival rate of gastric cancer patients ranges from 10%–30%. Patients of gastric cancer in severe stages are untreatable [1,2]. There is urgency to identify novel therapeutic agents that can reduce the mortality of cancer patients with lower side effects

Methods

Results

Conclusion