Inhibition of ABI2 Ubiquitination-Dependent Degradation Suppresses Breast Cancer Cell Growth via Down-regulating PI3K/Akt Signaling Pathway [RNAseq-20240420]

TNBC is a type of cancer that lacks receptor expression and has complex molecular mechanisms. Recent evidence shows that the ubiquitin-protease system is closely related to TNBC. In this study, we obtain a key ubiquitination regulatory substrate-abi2 protein by bioinformatics methods, which is also closely related to the survival and prognosis of TNBC. Further, through a series of experiments, we demonstrated that ABI2 expressed at a low level in TNBC tumors, and it has the ability to control cell cycle and inhibit TNBC cell migration, invasion and proliferation. Molecular mechanism studies proved E3 ligase CBLC could increase the ubiquitination degradation of ABI2 protein. Meanwhile, RNA-seq and IP experiments indicated that ABI2 can significantly inhibit PI3K/Akt signaling pathway via the interaction with Rho GTPase RAC1. Finally, we also found that the antibiotic Colistimethate could inhibit the growth of TNBC cells by inhibiting CBLC-induced ABI2 ubiquitination and down-regulating PI3K/Akt signaling pathway. Overall design: To identify the gene functions of ABI2, MDA-MB-231 cells were seeded in 6-well plates for 48 h and then transfected for gene overexpression. Briefly, the transfected plasmid containing ABI2 were used for gene overexpression, and MDA-MB-231 cells transfected with empty vector were used as a negative control. Pasmids were purchased from GenePharma (Shanghai, China).