GRLF1 is involved in the ploidy-control of urothelial cells and impairs the migration and invasion of bladder cancer cell lines in vitro

Abstract

This study aimed to identify and characterize the role of GRLF1 in human bladder cancer (BC) and the underlying molecular mechanisms of how GRLF1 regulates cellular functions. Mutations in the GRLF1 gene are reported in several human cancers, and functional studies indicate a crucial role of GRLF1 in genome stability and carcinogenesis. High throughput sequencing data from independent studies showed that GRLF1 is also frequently mutated in BC, but the contribution of GRLF1 to BC is unclear. Functional studies using shRNA- mediated gene knockdown in cells with high GRLF1 expression and ectopic GRLF1 expression in invasive BC cell lines with low GRLF1 expression demonstrated the effects of GRLF1 on genome stability, cell growth, and cell migration/invasion. These experiments proved that the depletion of GRLF1 impaired proliferation and induced aneuploidy in immortalized NHU cells with normal karyotype. GRLF1 knockdown induced S-phase arrest by inhibiting the activation of the RhoA-MAPK (ERK)-cyclin D signal transduction pathway in NHU cells. In summary, data presented in this study support the conclusion that GRLF1 may act as a cancer suppressor in the urothelial cells of the bladder and that alterations in GRLF1 sequence or reduced GRLF1 expression may promote BC initiation and/or progression.