Verteporfin inhibits cell proliferation and induces apoptosis in different subtypes of breast cancer cell lines without light activation

BACKGROUND: Breast cancer (BC) can be divided into five subtypes: Lumina1A, Lumina1B, HER-2 overexpression, Basal-like and Normal breast-like subtype, based on the differently expressed genes in breast cancer tissue. The Hippo signaling pathway plays an indispensable role in BC. The YAP gene is a terminal effector of Hippo pathway, and hyperactivation of YAP mediates tumorigenesis. As an inhibitor of YAP, non-photoactivated verteporfin (VP) can inhibit YAP-mediated tumor proliferation and angiogenesis by eliminating its interaction with TEAD. This study aimed to determine the effect and molecular mechanisms of VP-mediated inhibition of YAP in different subtypes of BC. METHODS: Luminal A, Luminal B and Basal-like BC cells were cultivated in vitro to study effects of VP on proliferation and apoptosis of these three molecular BC subtypes. RESULTS: Our experimental results showed that VP inhibited cell proliferation, YAP-TEAD interaction and expression of its downstream targets. VP also induced tumor cell apoptosis, and promoted the cleavage of Caspase-9 and PARP in the cells of various molecular subtypes of BC. CONCLUSION: These findings provide a basis for the use of VP as a potential anti-tumor therapeutic for BC by targeting the Hippo pathway effector YAP.