YAP represses the TEAD-NF-κB complex and inhibits the growth of clear cell renal cell carcinoma

The Hippo pathway effector YAP inhibits NF-κB signaling and ccRCC growth by opposing ZHX2

The prevailing view in the cancer field is that Hippo (Hpo) signaling pathway functions as a tumor suppressor pathway by blocking the oncogenic potential of the pathway effectors Yes1-associated transcriptional regulator (YAP)/transcriptional coactivator with PDZ-binding motif. However, YAP can also function as a context-dependent tumor suppressor in several types of cancer including clear cell renal cell carcinomas (ccRCCs). We find that, in addition to inhibiting hypoxia-inducible factor 2α, a major oncogenic driver in Von Hippel-Lindau-/- ccRCC, YAP also blocks nuclear factor κB (NF-κB) signaling in ccRCC to inhibit cancer cell growth under conditions where hypoxia-inducible factor 2α is dispensable. Mechanistically, YAP inhibits the expression of Zinc fingers and homeoboxes 2 (ZHX2), a Von Hippel-Lindau substrate and critical cofactor of NF-κB in ccRCC. Furthermore, YAP competes with ZHX2 for binding to the NF-κB subunit p65. Consequently, elevated nuclear YAP blocks the cooperativity between ZHX2 and the NF-κB subunit p65, leading to diminished NF-κB target gene expression. Pharmacological inhibition of Hpo kinase blocked NF-κB transcriptional program and suppressed ccRCC cell growth, which can be rescued by overexpression of ZHX2 or p65. Our study uncovers a crosstalk between the Hpo and NF-κB/ZHX2 pathways and its involvement in ccRCC growth inhibition, suggesting that targeting the Hpo pathway may provide a therapeutical opportunity for ccRCC treatment.

Regulatory roles of RNA binding proteins in the Hippo pathway

The Hippo pathway represents a highly conserved evolutionary pathway, dysfunction of which has been implicated in various diseases. RNA-binding proteins (RBPs) intricately modulate gene expression through interacting with non-coding RNAs or other proteins. To data, while an array of RBPs have been identified as modulators of the Hippo pathway, there remains a notable absence of a comprehensive review addressing the mechanistic regulations of RBPs in the transduction of Hippo signaling. Herein, this review aims to consolidate recent advances and elucidate the intricate mechanisms underlying RBPs binding to target RNA. It also explores the dynamic interplay between RBPs, non-coding RNAs, TFs, and DNA on chromatin. Additionally, it also outlines future perspectives, including the essential non-canonical functions of RBPs and emerging roles of non-canonical RBPs as transcription factors (TFs) in genes transcription. Overall, this review provides mechanistic insights into the roles of eukaryotic RBP proteins in the regulation of crucial signaling cascades.

Emerging Role of Hippo-YAP (Yes-Associated Protein)/TAZ (Transcriptional Coactivator with PDZ-Binding Motif) Pathway Dysregulation in Renal Cell Carcinoma Progression

Although Hippo-YAP/TAZ pathway involvement has been extensively studied in the development of certain cancers, the involvement of this cascade in kidney cancer progression is not well-established and, therefore, will be the focus of this review. Renal cell carcinoma (RCC), the most prevalent kidney tumor subtype, has a poor prognosis and a high mortality rate. Core Hippo signaling inactivation (e.g., LATS kinases) leads to the nuclear translocation of YAP/TAZ where they bind to co-transcriptional factors such as TEAD promoting transcription of genes which initiates various fibrotic and neoplastic diseases. Loss of expression of LATS1/2 kinase and activation of YAP/TAZ correlates with poor survival in RCC patients. Renal-specific ablation of LATS1 in mice leads to the spontaneous development of several subtypes of RCC in a YAP/TAZ-dependent manner. Genetic and pharmacological inactivation of YAP/TAZ reverses the oncogenic potential in LATS1-deficient mice, highlighting the therapeutic benefit of network targeting in RCC. Here, we explore the unique upstream controls and downstream consequences of the Hippo-YAP/TAZ pathway deregulation in renal cancer. This review critically evaluates the current literature on the role of the Hippo pathway in RCC progression and highlights the recent scientific evidence designating YAP/TAZ as novel therapeutic targets against kidney cancer.