Dual role of GRHL3 in bladder carcinogenesis is associated with histological subtypes

Grainyhead-like transcription factor 3 (GRHL3) is known to affect cancer development depending on subtypes in various entities. Here, we analyzed the subtype-specific role of GRHL3 in bladder carcinogenesis comparing common urothelial carcinoma (UC) with squamous bladder cancers (sq-BLCA). We examined GRHL3 mRNA and protein expression in cohorts of patient samples, its prognostic role as well as its functional impact on tumorigeneses in different molecular and histopathological subtypes of bladder cancer. We showed for GRHL3 a reverse expression in squamous and urothelial bladder cancer subtypes. Stably GRHL3 overexpressing EJ28 and SCaBER in vitro models revealed a tumor suppressive function in squamous and a oncogenic role in the urothelial cancer cells affecting cell migratory and invasive capacities. Transcriptomic profiling demonstrated highly subtype specific GRHL3 regulated expression networks coined by enrichment of genes involved in integrin mediated pathways. In SCaBER loss of RhoA GTPase activity was demonstrated associated with co-regulation of EIF4E3, a potential tumor suppressor gene. Thus, our data provide for the first time a detailed insight into the role of the transcription factor GRHL3 in different histopathological subtypes of bladder cancer.