Rb deficiency accelerates progression of carcinoma of the urinary bladder in vivo and in vitro through inhibiting autophagy and apoptosis.

Abstract

Urinary bladder cancer is known as a common cancer diagnosed across the world and results in significant mortality and morbidity rates among patients. The retinoblastoma (Rb) protein, as a main tumor suppressor, controls cellular responses to potentially oncogenic stimulation. Rb phosphorylation could disrupt E2F complex formation, resulting in diverse transcription factor dysfunction. In our study, we investigated how Rb is involved in controlling urinary bladder cancer progression. The results indicate that Rb expression is reduced in mice with urinary bladder tumor, and its suppression leads to urinary bladder cancer progression invivo and invitro. Rb mutation directly results in tumor size with lower survival rate invivo. Rb knockdown invitro promoted bladder tumor cell proliferation, migration and invasion. Interestingly, Rb knockout and knockdown result in autophagy and apoptosis inhibition via suppressing p53 and caspase-3 signaling pathways, enhancing bladder cancer development invitro and invivo. These findings reveal that Rb deficiency accelerated urinary bladder cancer progression, exposing an important role of Rb in suppressing urinary bladder cancer for treatment in the future.