Mechanism of miR-98-5p in gastric cancer cell proliferation, migration, and invasion through the USP44/CTCFL axis.

OBJECTIVES: Gastric cancer (GC) is the leading digestive malignancy with high incidence and mortality rate. microRNAs (miRs) play an important role in GC progresssion. This study aimed to investigate the effect of miR-98-5p on proliferation, migration, and invasion of GC cells. METHODS: The expression levels of miR-98-5p, ubiquitin specific peptidase 44 (USP44), and CCCTCbinding factor-like (CTCFL) in GC tissues and cells were identified using reversetranscription quantitative polymerase chain reaction and Western blot assay. The relationship between miR-98-5p expression/USP44 and the clinicopathological features in GC patients was analyzed. GC cell proliferation, invasion, and migration were evaluated by cell counting kit-8 and clone formation assays and Transwell assays. The bindings of miR-98-5p to USP44 and USP44 to CTCFL were examined using dualluciferase assay and co-immunoprecipitation. GC cells were treated with MG132 and the ubiquitination level of CTCFL was examined using ubiquitination assay. Rescue experiments were performed to verify the roles of USP44 and CTCFL in GC cells. RESULTS: miR-98-5p was downregulated in GC. miR-98-5p overexpression inhibited the proliferation, migration, and invasion of GC cells. miR-98-5p inhibited USP44 expression. USP44 bound to CTCFL and limited ubiquitination degradation of CTCFL. Overexpression of USP44 and CTCFL attenuated the inhibitory effects of miR-98-5p overexpression on GC cell progression. CONCLUSION: miR-98-5p overexpression limited USP44-mediated CTCFL deubiquitination, and suppressed CTCFL expression, mitigating GC cell proliferation, migration, and invasion.