Asporin promotes cell proliferation via interacting with PSMD2 in gastric cancer.

Asporin (ASPN), a member of small leucine-rich repeat proteoglycan (SLRP) family of proteins, serves important roles in diverse biological responses and disease conditions. We tested the hypothesis that ASPN regulated proliferation of gastric cancer (GC) cells and identified its down-stream regulators. ASPN promoted the proliferation of GC cells. We identified the effector of this effect as proteasome 26S subunit non-ATPase 2 (PSMD2) which is known to regulate proliferation through suppression of DUSP7, WIP1 and PTEN and then inducing the phosphorylation of ERK, P38 and AKT. PSMD2 co-immunoprecipitated with ASPN from GC cell lysates and co-localized with PSMD2 inside GC cells. Moreover, knockdown of ASPN significantly increased the expression of DUSP7, WIP1 and PTEN and led to a repression in the phosphorylation of ERK, P38 and AKT. These changes were counteracted by knockdown of PSMD2. In conclusion, ASPN promotes cell proliferation by interacting with PSMD2, and down-regulation of its effectors and serves as a potential therapeutic target in GC.