Depletion of OLFM4 gene inhibits cell growth and increases sensitization to hydrogen peroxide and tumor necrosis factor-alpha induced-apoptosis in gastric cancer cells

Rui-Hua Liu,Li-Ming Bao,Yi Huang,Li-Ya Wu,Li-Wen Yue,Xue Jiang,Mei-Hua Yang,Na Ang,Hua Xiang,Hua-An Yang

doi:10.1186/1423-0127-19-38

Abstract

BackgroundHuman olfactomedin 4 (OLFM4) gene is a secreted glycoprotein more commonly known as the anti-apoptotic molecule GW112. OLFM4 is found to be frequently up-regulated in many types of human tumors including gastric cancer and it was believed to play significant role in the progression of gastric cancer. Although the function of OLFM4 has been indicated in many studies, recent evidence strongly suggests a cell or tissue type-dependent role of OLFM4 in cell growth and apoptosis. The aim of this study is to examine the role of gastric cancer-specific expression of OLFM4 in cell growth and apoptosis resistance.MethodsOLFM4 expression was eliminated by RNA interference in SGC-7901 and MKN45 cells. Cell proliferation, anchorage-independent growth, cell cycle and apoptosis were characterized in vitro. Tumorigenicity was analyzed in vivo. The apoptosis and caspase-3 activation in response to hydrogen peroxide (H2O2) or tumor necrosis factor-alpha (TNF α) were assessed in the presence or absence of caspase inhibitor Z-VAD-fmk.ResultsThe elimination of OLFM4 protein by RNA interference in SGC-7901 and MKN45 cells significantly inhibits tumorigenicity both in vitro and in vivo by induction of cell G1 arrest (all P < 0.01). OLFM4 knockdown did not trigger obvious cell apoptosis but increased H2O2 or TNF α-induced apoptosis and caspase-3 activity (all P < 0.01). Treatment of Z-VAD-fmk attenuated caspase-3 activity and significantly reversed the H2O2 or TNF α-induced apoptosis in OLFM4 knockdown cells (all P < 0.01).ConclusionOur study suggests that depletion of OLFM4 significantly inhibits tumorigenicity of the gastric cancer SGC-7901 and MKN45 cells. Blocking OLFM4 expression can sensitize gastric cancer cells to H2O2 or TNF α treatment by increasing caspase-3 dependent apoptosis. A combination strategy based on OLFM4 inhibition and anticancer drugs treatment may provide therapeutic potential in gastric cancer intervention.

Highlights

Human olfactomedin 4 (OLFM4) gene is a secreted glycoprotein more commonly known as the antiapoptotic molecule GW112
Human OLFM4, originally termed human cloned from myeloid precursor cells after granulocyte colony-stimulating factor stimulation [1], is a secreted glycoprotein more commonly known as the anti-apoptotic molecule GW112 [2,3]
Efficient knock down of OLFM4 gene by plasmidmediated siRNA in gastric cancer cells OLFM4 protein expression pattern was investigated in gastric cancer BGC-823, HGC-27, SGC-7901, MKN28, MKN45 cells and normal GES-1 control cells (Figure 1A)

Summary

Introduction

Human olfactomedin 4 (OLFM4) gene is a secreted glycoprotein more commonly known as the antiapoptotic molecule GW112. Up-regulated OLFM4 showed a strong anti-apoptotic activity in mouse lymphoid vein endothelial SVEC cells and human adenocarcinoma HeLa cells [1,2], whereas recent findings suggested a proapoptotic effect of OLFM4 in human myeloid leukemia HL-60 cells [16]. Evidence from these studies strongly suggests that roles of OLFM4 in cell growth control and apoptosis may depend on the cell or tissue type [10,13,14,15]. Very limited data concerning the role of OLFM4 in the cell growth and apoptosis profiles of gastric cancer cells has been published

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