ABRACL upregulated by transcription factor CBX4 promotes proliferation and migration and inhibits the apoptosis of gastric cancer cells.

[BACKGROUND] Gastric cancer (GC) is a predominant health concern in many countries. Actin-binding Rho activating C-terminal-like (ABRACL) belongs to a new family of low molecular weight proteins and has been implicated in cancers. This study was implemented to elucidate the role and mechanism of ABRACL in GC.

[METHODS] The mRNA and protein expression of ABRACL and CBX4 in human gastric epithelium cell line GES-1 and GC cell lines was assessed with RT-qPCR and western blot. The transfection efficacy of sh-ABRACL, oe-CBX4, and sh-CBX4 was examined with RT-qPCR and western blot. AGS cell proliferation, migration, and invasion were evaluated using CCK-8, colony formation assay, wound healing, and Transwell assays, respectively. With western blot analysis, flow cytometry, and caspase-3 assay kits, the expressions of MMP2 and MMP9, cell apoptosis, and caspase-3 activity were estimated. Western blot was adopted to estimate the contents of apoptosis-related proteins. Luciferase reporter and chromatin immunoprecipitation (ChIP) were applied to verify the interaction between ABRACL and CBX4.

[RESULTS] The expression of ABRACL and CBX4 was increased in GC tissues and cells. After interfering with ABRACL, the proliferation, migration, and invasion of GC cells were inhibited while apoptosis was promoted. We also discovered that CBX4 could bind to ABRACL and transcriptionally regulate ABRACL expression in AGS cells. Rescue experiments revealed that CBX4 overexpression partially reversed the regulatory effects of ABRACL silencing on the proliferation, migration, invasion, and apoptosis of GC cells.

[CONCLUSION] Collectively, ABRACL transcriptionally upregulated by CBX4 promoted the malignant progression of GC.