Abstract 2013P
Background
Clinically, hypoxia and the expression of the hypoxia-inducible factors-1α (HIF-1α) are associated with increased distant metastasis and poor survival in gastric cancer (GC). In this study, we set out from the cellular interaction to further explain the molecular mechanism of invasion and metastasis of GC cells under hypoxic conditions.
Methods
GC cells were cultured under 1% O2 (hypoxia gastric cancer, HGC) and 20% O2 condition (normoxia gastric cancer, NGC). Exosomes from GC were extracted by ultracentrifugation. Next generation sequence (NGS) and R were used to recognize the differentially expressed lncRNAs. RNA-pulldown and mass spectrometry analysis were recruited to investigate the binding protein of target lncRNA. Luciferase assay were used to infer and prove the binding of promoter sequence of lncRNA to transcription factor HIF-1α. Migration assay, permeability assay, and angiogenesis assay were used to assess the role of HGC-derived exosomes in angiogenesis.
Results
HGC-medium induced angiogenesis. NGS and bioinformatics analysis showed that lncRNA PCGEM1 (prostate cancer gene expression marker 1) was specifically expressed in HGC exosomes. PCGEM1 was also over-expressed in GC cells and tissue and which was also a serum diagnostic molecular marker. HIF-1α, as a transcription factor, can bind to the promoter sequence of PCGEM1, promotes the overexpression of PCGEM1 in GC. Exosome-PCGEM1 could be internalized by HUVEC. RNA pull-down assay and mass spectrometry analysis showed that AXL bound with PCGEM1 directly in HUVEC. PCGEM1 could maintain the stability of AXL and reduce its ubiquitination degradation, thus induced angiogenesis through the ERK pathway.
Conclusions
Hypoxia can up-regulated the expression of lncRNA PCGEM1. The overexpression PCGEM1 can be encapsulated into exosomes. These exosomes promoted angiogenesis. We considered PCGEM1 as a "scaffold” combined with AXL and prompted the invasion and metastasis of GC.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.