DAG/PKCδ and IP3/Ca²⁺/CaMK IIβ Operate in Parallel to Each Other in PLCγ1-Driven Cell Proliferation and Migration of Human Gastric Adenocarcinoma Cells, through Akt/mTOR/S6 Pathway.

Bingchang Zhang,Bing Zhang,Lianzhi Dai,Fen Wang,Xiaolei Chen,Luhua Zhuang,Chun Xia

doi:10.3390/ijms161226116

Abstract

Phosphoinositide specific phospholipase Cγ (PLCγ) activates diacylglycerol (DAG)/protein kinase C (PKC) and inositol 1,4,5-trisphosphate (IP3)/Ca2+/calmodulin-dependent protein kinase II (CaMK II) axes to regulate import events in some cancer cells, including gastric adenocarcinoma cells. However, whether DAG/PKCδ and IP3/Ca2+/CaMK IIβ axes are simultaneously involved in PLCγ1-driven cell proliferation and migration of human gastric adenocarcinoma cells and the underlying mechanism are not elucidated. Here, we investigated the role of DAG/PKCδ or CaMK IIβ in PLCγ1-driven cell proliferation and migration of human gastric adenocarcinoma cells, using the BGC-823 cell line. The results indicated that the inhibition of PKCδ and CaMK IIβ could block cell proliferation and migration of BGC-823 cells as well as the effect of inhibiting PLCγ1, including the decrease of cell viability, the increase of apoptotic index, the down-regulation of matrix metalloproteinase (MMP) 9 expression level, and the decrease of cell migration rate. Both DAG/PKCδ and CaMK IIβ triggered protein kinase B (Akt)/mammalian target of rapamycin (mTOR)/S6 pathway to regulate protein synthesis. The data indicate that DAG/PKCδ and IP3/Ca2+/CaMK IIβ operate in parallel to each other in PLCγ1-driven cell proliferation and migration of human gastric adenocarcinoma cells through Akt/mTOR/S6 pathway, with important implication for validating PLCγ1 as a molecular biomarker in early gastric cancer diagnosis and disease surveillance.

Highlights

Human gastric cancer is the second leading cause of cancer death and the fourth most prevalent malignancy worldwide [1]
The regulatory mechanism related to Akt, mammalian target of rapamycin (mTOR), and S6 signal molecules was investigated. Both DAG/PKCδ and IP3/Ca2+/CaMK IIβ operate in parallel to each other in PLCγ1-driven cell proliferation and migration of human gastric adenocarcinoma cells
To investigate whether DAG/PKCδ and IP3/Ca2+/CaMK IIβ were simultaneously involved in regulating cell proliferation and apoptosis in human gastric adenocarcinoma cells, BGC-823 cells were treated with those inhibitors, U73122 (PLCγ inhibitor), KN93 (CaMK II inhibitor) and R59949 (DAG-kinase inhibitor), or were transfected with lentiviral-shorthairpin RNA (shRNA) of PKCδ or CaMK IIβ vectors for different time points, followed by the detection of cell viability using an MTT assay and apoptotic index using DAPI or Propidium Iodide (PI) staining

Summary

Introduction

Human gastric cancer is the second leading cause of cancer death and the fourth most prevalent malignancy worldwide [1]. Recent literature has shown the involvement of important signal molecules in the pathogenesis of gastric cancers, which is beneficial to developing efficacious molecular biomarkers for early gastric cancer diagnosis and disease surveillance. The expression of cyclin D1, p21 and p27, alone or in combination, are early events in gastric tumorigenesis and may serve as a candidate molecular marker for the early gastric carcinoma [4]. Mitogen-activated protein kinase (MAPK) kinase 4 (MKK4) kinase expression could serve as a significant prognostic factor for disease-free survival and for overall survival in human gastric cancer [5]. Studying the expressions of important signal molecules in the pathogenesis of gastric cancer and understanding the underlying transduction mechanism are required to validate the molecular biomarkers

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Results

Conclusion