WWOX Loses the Ability to Regulate Oncogenic AP-2γ and Synergizes with Tumor Suppressor AP-2α in High-Grade Bladder Cancer

Abstract

The cytogenic locus of the WWOX gene overlaps with the second most active fragile site, FRA16D, which is present at a higher frequency in bladder cancer (BLCA) patients with smoking habit, a known risk factor of this tumor. Recently, we demonstrated the relevance of the role of WWOX in grade 2 BLCA in collaboration with two AP-2 transcription factors whose molecular actions supported or opposed pro-cancerous events, suggesting a distinct character. As further research is needed on higher grades, the aim of the present study was to examine WWOX-AP-2 functionality in grade 3 and 4 BLCA using equivalent in vitro methodology with additional transcriptome profiling of cellular variants. WWOX and AP-2α demonstrated similar anti-cancer functionality in most biological processes with subtle differences in MMP-2/9 regulation; this contradicted that of AP-2γ, whose actions potentiated cancer progression. Simultaneous overexpression of WWOX and AP-2α/AP-2γ revealed that single discrepancies appear in WWOX-AP-2α collaboration but only at the highest BLCA grade; WWOX-AP-2α collaboration was considered anti-cancer. However, WWOX only appeared to have residual activity against oncogenic AP-2γ in grade 3 and 4: variants with either AP-2γ overexpression alone or combined WWOX and AP-2γ overexpression demonstrated similar pro-tumoral behavior. Transcriptome profiling with further gene ontology certified biological processes investigated in vitro and indicated groups of genes consisting of AP-2 targets and molecules worth investigation as biomarkers. In conclusion, tumor suppressor synergism between WWOX and AP-2α is unimpaired in high-grade BLCA compared to intermediate grade, yet the ability of WWOX to guide oncogenic AP-2γ is almost completely lost.

TFAP2 paralogs facilitate chromatin access for MITF at pigmentation and cell proliferation genes

“…The activating enhancer-binding family of transcription factors, comprising five members, TFAP2A-E, regulate development of many cell types and organs including neural crest, placodes, epidermis, trophectoderm, heart, kidney, and brain [ 19 – 28 ]. In several contexts, including melanocyte differentiation, TFAP2 paralogs function redundantly [ 10 , 29 – 31 ]. For instance, in zebrafish tfap2a loss-of-function mutant embryos the number of melanocytes is lower than normal and pigmentation is delayed relative to in wild-type embryos; this phenotype is exacerbated if tfap2a mutant embryos are also depleted of tfap2e expression with antisense morpholinos [ 10 ].…”

The WWOX/HIF1A Axis Downregulation Alters Glucose Metabolism and Predispose to Metabolic Disorders

“…The first WW domain is responsible for majority of pathways in which WWOX is involved through binding the PPxY (where P is proline, Y is a tyrosine and x is any amino acid) motifs of a partner [ 35 ]. Several WWOX protein partners have been identified, for example p73 [ 36 ], ErbB4 [ 37 ], Ap2α and γ [ 38 , 39 ], Runx2 [ 40 ], Dvl2 [ 41 ] and HIF1α [ 26 ], so WWOX is involved in many cellular process, including metabolism. The first reports described Wwox -null mice, which died by 3 weeks after birth and demonstrated defects in growth rate and steroid metabolism as a consequence of reduced serum calcium, hypoproteinuria and hypoglycemia [ 42 ].…”

Determination of WWOX Function in Modulating Cellular Pathways Activated by AP-2α and AP-2γ Transcription Factors in Bladder Cancer

“…In view of the aforementioned data, this research was designed to limit the impact of heterogeneity on our previous findings [6,7] for bladder cancer (BLCA); thus assessing the influence of investigated molecules on BLCA signaling. Namely, we have recently considered it rational to investigate the biological effect of three genes on bladder cancer, 2 of 22 i.e., WW Domain Containing Oxidoreductase (WWOX), Transcription Factor AP-2 Alpha (TFAP2A) and Transcription Factor AP-2 Gamma (TFAP2C), the last two encoding Activating Enhancer-Binding Protein 2 Alpha (AP-2α) and AP-2γ, respectively.…”

“…In general, the first tryptophan domain of WWOX is responsible for binding the proline-rich motif of AP-2α/γ [8] which leads to sequestration of AP-2 proteins out of the nucleus and thus reduces their transcriptional activity [9]; AP-2γ is bound by WWOX more strongly than AP-2α [8]. Cellular variants of three BLCA cell lines (RT-112, HT-1376 and CAL-29), developed to obtain specific expression of these genes, demonstrated distinct phenotypes when investigating a range of biological processes through in vitro assays [6,7]. The findings indicate that WWOX and AP-2α behave as tumor suppressors and may act synergistically while AP-2γ is an oncogene that can be guided by WWOX against tumor progression.…”