Fragile Gene WWOX Guides TFAP2A/TFAP2C-Dependent Actions Against Tumor Progression in Grade II Bladder Cancer

Abstract

IntroductionThe presence of common fragile sites is associated with no-accidental chromosomal instability which occurs prior to carcinogenesis. The WWOX gene spans the second most active fragile site: FRA16D. Chromosomal breakage at this site is more common in bladder cancer patients who are tobacco smokers which suggests the importance of WWOX gene loss regarding bladder carcinogenesis. Tryptophan domains of WWOX are known to recognize motifs of other proteins such as AP-2α and AP-2γ allowing protein-protein interactions. While the roles of both AP-2 transcription factors are important for bladder carcinogenesis, their nature is different. Based on the literature, AP-2γ appears to be oncogenic, whereas AP-2α mainly exhibits tumor suppressor character. Presumably, the interaction between WWOX and both transcription factors regulates thousands of genes, hence the aim of the present study was to determine WWOX, AP-2α, and AP-2γ function in modulating biological processes of bladder cancer.MethodsRT-112 cell line (grade II bladder cancer) was subjected to two stable lentiviral transductions. Overall, this resulted in six variants to investigate distinct WWOX, AP-2α, or AP-2γ function as well as WWOX in collaboration with a particular transcription factor. Cellular models were examined with immunocytochemical staining and in terms of differences in biological processes using assays investigating cell viability, proliferation, apoptosis, adhesion, clonogenicity, migration, activity of metalloproteinases and 3D culture growth.ResultsWWOX overexpression increased apoptosis but decreased cell viability, migration and large spatial colonies. AP-2α overexpression decreased tumor cell viability, migratory potential, matrix metalloproteinase-2 activity and clonogenicity. AP-2γ overexpression decreased matrix metalloproteinase-2 activity but increased wound healing, adhesion, clonogenicity and spatial colony formation. WWOX and AP-2α overexpression induced apoptosis but decreased cell viability, adhesion, matrix metalloproteinase-2 activity, overall number of cultured colonies and migration rate. WWOX and AP-2γ overexpression decreased tumor cell viability, proliferation potential, adhesion, clonogenicity and the ability to create spatial structures, but also increased apoptosis or migration rate.ConclusionCo-overexpression of WWOX with AP-2α or WWOX with AP-2γ resulted in a net anti-tumor effect. However, considering this research findings and the difference between AP-2α and AP-2γ, we suggest that this similarity is due to a divergent behavior of WWOX.

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

“…Mitochondrial redox potential indicates cell viability; this assay was analyzed as described previously [8], i.e., the variant was considered meaningful if at least three measurement points met statistical significance. Thus, HT-1376 cell viability decreased after WWOX overexpression (mean 1.12-fold) but increased after AP-2γ overexpression (mean 1.16-fold).…”

“…It was found that both WWOX and AP-2α hinder cancer progression and may act synergistically. In contrast, AP-2γ supports tumor development, but its action may be diminished by WWOX, resulting in a net anti-tumor effect [8]. Nonetheless, the conclusion of previous work was based on grade 2 (G2) bladder carcinoma; hence, profound examination is advisable on higher grades of BLCA.…”

“…Moreover, allelic loss at WWOX-proximal locus 16q24 was found to be related to tumor progression in up to 45% of BLCAs [7]. Recently, we examined the role of WWOX in conjunction with two interacting proteins, which together orchestrated biological processes diversely in BLCA depending on their cellular level [8]. These were two Activating Enhancer-Binding Protein 2 (AP-2) Transcription Factors (TFs), AP-2α and AP-2γ, members of the AP-2 family, whose natural function is related to early development regulation [9], but which are also involved in carcinogenesis [10][11][12][13][14], including BLCA [15][16][17].…”

Modeling tissue-specific breakpoint proximity of structural variations from 2,382 whole-genomes to identify cancer drivers

“…6e). WWOX is within a known fragile site and has been reported in several studies of different tumor types including breast, prostate, lung, esophagus, cervical, ovarian and bladder cancers [57][58][59][60][61].…”

Plasma exosome-derived fragile-site associated tumor suppressor is a powerful predictor of prognosis in patients with ovarian cancer

“…Oncology research includes the discovery of novel tumor suppressor genes and investigations of their roles in the development of tumors (7). Common fragile sites (CFS) are site-specific unstable regions in the normal genome and include the rare fragile sites (8). While the role of rare fragile sites in tumors remains unclear, CFS is consistent for many tumor genome mutations, and they are closely related to the occurrence and development of tumors (9).…”