Non-visual
arrestins (β-
arrestins) are endocytic
proteins that mediate agonist-activated GPCRs internalization and signaling pathways in an independent manner. The involvement of β-
arrestins in
cancer invasion and
metastasis is increasingly reported. So, it is hypothesized that inhibition of β-
arrestins may diminish the survival chances of
cancer cells. This study aimed to evaluate the in vitro impact of inhibiting β-
arrestins on the autophagic and/or apoptotic responsiveness of
breast cancer cells. We used
Barbadin to selectively inhibit β-Arr/AP2 interaction in AVP-stimulated V2R receptor of
triple-negative breast cancer cells (MDA MB-231). Autophagy was assessed by the
microtubule-associated protein 1 light chain 3-II (LC3II), apoptosis was measured by
Annexin-V/PI staining and cell cycle distribution was investigated based upon the
DNA content using flow cytometry.
Barbadin reduced cell viability to 69.1% and increased the autophagy marker LC3II and its autophagic effect disappeared in cells transiently starved in Earle's balanced
salt solution (EBSS). Also,
Barbadin mildly enhanced the expression of P62
mRNA and arrested 63.7% of cells in G0/G1 phase. In parallel, the
drug-induced apoptosis in 29.9% of cells (by AV/PI) and 27.8% of cells were trapped in sub-G1 phase. The apoptotic effect of
Barbadin was enhanced when autophagy was inhibited by the PI3K inhibitor (
Wortmannin). Conclusively, the data demonstrate the dual autophagic and apoptotic effects of β-βArr/AP2 inhibition in
triple-negative breast cancer cells. These observations nominate β-Arrs as selective targets in
breast cancer treatment.