ORAI2 promotes tumorigenesis and metastasis in gastric cancer via activation of the PI3K/Akt and FAK/MAPK/ERK pathways


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Shayi Wu1
1University of Hong Kong

Abstract

Background

Gastric cancer (GC), an aggressive disease with heterogeneous features, has contributed to a notable proportion of cancer mortality worldwide, but the genetic underlining of this disease remains unexplored. The aim of this study is to uncover the recurrent genetic changes, elucidate their roles and identify new biomarkers for improving clinical outcomes.

Method

Western blotting and immunohistochemistry (IHC) were performed to detect the expression level of ORAI2. Real-time quantitative PCR (Q-PCR) and immunofluorescence (IF) were utilized to explore the associated store-operated Ca2+ (SOC) partners and adhesion molecules, respectively. Flow cytometry was adopted to examine the ability of ORAI2 in cell cycle transition. Ca2+ influx measurement by Fluo-4 AM was employed to evaluate the SOC activity. Time-lapse imaging with fluorescence recovery after photo-bleaching (FRAP) was applied to study the ability of ORAI2 in modulating focal adhesion (FA) dynamics. Tumor-promotive ability and pro-metastatic effect of ORAI2 were determined by both in-vitro and in-vivo assays.

Results

ORAI2 was frequently upregulated in GC, which was significantly correlated with poor differentiation (P<0.0001) and invasion (P=0.033). Q-PCR and IHC revealed STIMs as promising SOC partners of ORAI2, while IF and FRAP illustrated ORAI2 to be responsible for FA dynamics. Functional assays evidenced that ORAI2 could promote cell motility, tumor formation and metastasis in both cell lines and mice. Ca2+ influx assay verified the ability of ORAI2 in mediating SOC current. Further investigations demonstrated that PI3K/Akt activation driven by ORAI2-modulated SOC entry was accounted for tumorigenesis in GC, and ORAI2-induced FAK/MAPK/ERK activation could facilitate FA turnover at rear-edge of the cell, a process critical for cancer cell migration, invasion and metastasis.

Conclusion

Our results demonstrate that ORAI2 is a novel gene that plays an important role in the migration and metastasis of GC. The findings uncover the translational potential to advance drug discovery along the ORAI signaling pathway.