Arsenic trioxide inhibits the activity of SphK1 by decreasing the level of phosphatidylserine and phosphatidic acid in the human gastric cancer cell line MGC-803

Pei Liu,Xiaoqiong Ma,Zhe Chen

doi:10.32604/biocell.2021.015786

Abstract

Sphingosine kinase 1 (SphK1) is an important synthetase during the synthesis of sphingosine-1-phosphate (S1P) from sphingosine (Sph). Previous studies demonstrated that arsenic trioxide (As2O3) could reduce the level of S1P in human gastric cancer cell line MGC-803, indicating that As2O3 may inhibit the activity of SphK1. In this study, the effect of As2O3 on the SphK1 activation pathway was investigated. Western blot and quantitative real-time PCR analysis were used to evaluate the changes in protein and mRNA levels. The multi-dimensional mass spectrometry-based shotgun lipidomics method (MDMS-SL) was used for the quantitative detection of phosphatidylserine (PS) and phosphatidic acid (PA). The results revealed that As2O3 did not affect the protein and mRNA expression of SphK1 in the MGC-803 cells. However, As2O3 increased the levels of p-ERK1/2 and CIB1 in the SphK1 activation pathway and decreased the levels of PS and PA in the MGC-803 cells. The outcomes suggested that As2O3 may enhance the activity of SphK1 by increasing the levels of p-ERK1/2 and CIB1 and decrease the activity of SphK1 by decreasing the levels of PS and PA. It was suggested that the inhibition effect is stronger and resulting in an overall decrease in the activity of SphK1.

Highlights

Western blotting analysis of Sphingosine kinase 1 (SphK1), p-ERK1/2, PP2A, and CIB1 as well as QPCR of SphK1 The MGC-803 cells were treated with different concentrations of iAsIII for 24 h, and the total proteins and RNAs were isolated and analyzed
As2O3 could enhance the levels of p-ERK1/2 and CIB1 in the pathway, indicating that As2O3 might promote the activation of SphK1
Our previous investigations inferred that As2O3 inhibited the activity of SphK1; based on this work, it was suggested that As2O3 could inhibit the activity of SphK1 by decreasing the cellular levels of PS and phosphatidic acid (PA)

Summary

Introduction

Gastric cancer is a common malignant tumor in the world. More than 70% of the new gastric cancer cases occurred in developing countries, and about 50% occurred in eastern Asia, mainly in China (Ferlay et al, 2015). Arsenic trioxide (As2O3) exhibits broad antitumor activity and is able to reverse tumor cell drug resistance. As2O3 can induce apoptosis by acting on apoptosis-related genes. It affects the expression of p53, Bcl-2, and caspases (Li et al, 2009; Park and Kim, 2012; Yu et al, 2007), downregulates the expression of cell transcription factor Sox (Hui and Zhang, 2011), survivin protein, and phosphorylated Akt protein in the cells (Chiu et al, 2011; Yuan et al, 2011), and inhibits cell proliferation (Li et al, 2011).

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