ASAP3 disrupts the ASAP1-ARHGAP12 interaction to inhibit RhoA activity, suppressing YAP/TAZ activation and the oncogenesis and progression of gastric cancer

Background Gastric cancer (GC) has high global mortality, with limited efficacy of advanced therapies due to unclear pathogenesis. While other ASAP family members like ASAP1 are recognized oncoproteins, the role of ASAP3 in GC is poorly understood. This study aimed to investigate the function and mechanisms of ASAP3 in GC. Methods The biological effects of ASAP3 were assessed in vitro using AGS and HGC-27 GC cell lines with ASAP3 overexpression or knockdown, evaluating proliferation, apoptosis, migration, and invasion. A subcutaneous xenograft model was used for in vivo validation. Underlying mechanisms were explored via transcriptomics, proteomics, and molecular biology techniques including co-immunoprecipitation (co-IP) and RhoA activation pull down. Results ASAP3 expression in HGC-27 cells was significantly higher than that in AGS cells. Functional experiments demonstrated that ASAP3 overexpression suppressed GC cell proliferation, migration, invasion, induced G0/G1 arrest/apoptosis, and inhibited tumor growth, while its knockdown promoted these malignant phenotypes. Then, transcriptomic and proteomic analyses respectively identified 382/714 DEMs and 98/66 DEPs between sh-ASAP3-HGC-27/oe-ASAP3-AGS and sh-NC-HGC-27/oe-NC-AGS cells, which significantly enriched in Hippo pathway, and GTPase regulation. RT-qPCR showed ASAP3 silencing in HGC-27 cells upregulated CCN1 , AMOTL2 while downregulated CCN2 , while ASAP3 overexpression in AGS cells reversed these trends. Western blot further showed ASAP3 silencing reduced the phosphorylation of MST1/2, LATS1/2, YAP, and TAZ, whereas ASAP3 overexpression in AGS cells enhanced their phosphorylation. Finally, ASAP3 could inhibit RhoA activity and thus suppress YAP/TAZ activation by interfering with the ASAP1-ARHGAP12 interaction. Conclusions ASAP3 may inhibit GC oncogenesis/progression by disrupting ASAP1-ARHGAP12 to suppress RhoA/YAP/TAZ, serving as a potential GC therapeutic target.