APRIL depletion induces cell cycle arrest and apoptosis through blocking TGF-β1/ERK signaling pathway in human colorectal cancer cells

It is well documented that a proliferation-inducing ligand (APRIL), a newly found member of tumor necrosis factor superfamily, overexpressed in the majority of malignancies, plays a potential role in the occurrence and development of these tumors. Herein, we demonstrated that APRIL depletion by using RNA interference in human colorectal cancer (CRC) COLO 205 and SW480 cells resulted in cell proliferation inhibition and evoked cell cycle arrest in G0/G1 phase and apoptosis, coupled with decrease in CDK2, Cyclin D1, Bcl-2 expression and an increase of p21 and Bax expression. In addition, the decreased expression of transforming growth factor-beta 1 (TGF-beta 1) and p-ERK was also showed in siRNA-APRIL transfected COLO 205 and SW480 cells, whereas the protein expression levels of Smad2/3, p-Smad2/3, and ERK were not significantly changed. Taken together, our results indicate that APRIL depletion induces cell cycle arrest and apoptosis partly through blocking noncanonical TGF-beta 1/ERK, rather than canonical TGF-beta 1/Smad2/3, signaling pathway in CRC cells. Moreover, our study highlights APRIL as a potential molecular target for the therapy of CRC.