Loss of DeltaNp63alpha promotes invasion of urothelial carcinomas via N-cadherin/Src homology and collagen/extracellular signal-regulated kinase pathway

ΔNp63 silencing, DNA methylation shifts, and epithelial-mesenchymal transition resulted from TAp63 genome editing in squamous cell carcinoma

TP63 (p63) is strongly expressed in lower-grade carcinomas of the head and neck, skin, breast, and urothelium to maintain a well-differentiated phenotype. TP63 has two transcription start sites at exons 1 and 3' that produce TAp63 and ΔNp63 isoforms, respectively. The major protein, ΔNp63α, epigenetically activates genes essential for epidermal/craniofacial differentiation, including ΔNp63 itself. To examine the specific role of weakly expressed TAp63, we disrupted exon 1 using CRISPR-Cas9 homology-directed repair in a head and neck squamous cell carcinoma (SCC) line. Surprisingly, TAp63 knockout cells having either monoallelic GFP cassette insertion paired with a frameshift deletion allele or biallelic GFP cassette insertion exhibited ΔNp63 silencing. Loss of keratinocyte-specific gene expression, switching of intermediate filament genes from KRT(s) to VIM, and suppression of cell-cell and cell-matrix adhesion components indicated the core events of epithelial-mesenchymal transition. Many of the positively and negatively affected genes, including ΔNp63, displayed local DNA methylation changes. Furthermore, ΔNp63 expression was partially rescued by transfection of the TAp63 knockout cells with TAp63α and application of DNA methyltransferase inhibitor zebularine. These results suggest that TAp63, a minor part of the TP63 gene, may be involved in the auto-activation mechanism of ΔNp63 by which the keratinocyte-specific epigenome is maintained in SCC.

Adverse Prognostic Impact of Diagnostic Ureterorenoscopy in a Subset of Patients with High-Risk Upper Tract Urothelial Carcinoma Treated with Radical Nephroureterectomy

Background: We hypothesized that diagnostic ureterorenoscopy (URS) may adversely affect prognosis in a subset of patients with high-risk upper tract urothelial carcinoma (UTUC) undergoing radical nephroureterectomy (RNU). Methods: The present retrospective study included 143 patients with UTUC treated between 2010 and 2021 at two tertiary care hospitals, of whom 79 received URS prior to RNU. Subgroups were stratified by clinicopathological variables relevant to prognosis. The primary endpoint was to evaluate the prognostic impact of URS on overall survival (OS) and progression-free survival (PFS) after RNU. Results: During follow-up (median 54 months for survivors), 32 cases of all-cause mortality and 40 cases of progression were recorded. No significant difference was found in OS or PFS between patients with and without URS. Subgroup analysis demonstrated that URS was significantly associated with worse OS (p < 0.001) and PFS (p = 0.008) in 29 patients with non-papillary and ≥pT3 UTUC. Importantly, URS did not have any adverse effects on prognosis in 62 patients with papillary and ≤pT2 UTUC (p = 0.005). Conclusions: URS may adversely affect prognosis of UTUC patients, specifically non-papillary and ≥pT3 disease. URS may better be avoided in patients with high-risk UTUC features unless URS is necessary to diagnose UTUC. This study also corroborates the oncological safety of URS in those with low-risk UTUC.

Prognostic role of ΔNp63 expression in canine transitional cell carcinoma of the urinary bladder

Background

Decreased p63 protein expression in canine transitional cell carcinoma (TCC) of the urinary bladder is associated with vascular invasion of the tumor, metastasis, and shortened survival. ΔNp63, an isoform of p63, is downregulated in high-grade invasive urothelial carcinoma in humans. However, the clinical significance of ΔNp63 expression in canine urinary bladder tumors is unknown. Therefore, it is essential to investigate ΔNp63 expression patterns in TCC, the most common urinary bladder tumor in dogs.

Aim

This study aimed to evaluate the expression and role of ΔNp63 in canine TCC of the urinary bladder.

Methods

ΔNp63 expression was compared between the normal canine urinary bladder, polypoid cystitis, and TCC. The correlation of ΔNp63 expression with histopathological and clinical findings were further evaluated, and its usefulness as a prognostic factor was examined.

Results

We observed that ΔNp63 was highly expressed in dogs' normal urinary bladder and polypoid cystitis, and its expression levels were low in TCC. Furthermore, low levels of ΔNp63 expression were associated with vascular invasion, metastasis, and shortened survival in dogs with TCC.

Conclusion

These results indicate that ΔNp63 expression could serve as a valuable biomarker for invasion, metastasis, and prognosis of canine TCC of the urinary bladder.

TMEM116 is required for lung cancer cell motility and metastasis through PDK1 signaling pathway

Transmembrane protein (TMEM) is a family of protein that spans cytoplasmic membranes and allows cell-cell and cell-environment communication. Dysregulation of TMEMs has been observed in multiple cancers. However, little is known about TMEM116 in cancer development. In this study, we demonstrate that TMEM116 is highly expressed in non-small-cell lung cancer (NSCLC) tissues and cell lines. Inactivation of TMEM116 reduced cell proliferation, migration and invasiveness of human cancer cells and suppressed A549 induced tumor metastasis in mouse lungs. In addition, TMEM116 deficiency inhibited PDK1-AKT-FOXO3A signaling pathway, resulting in accumulation of TAp63, while activation of PDK1 largely reversed the TMEM116 deficiency induced defects in cancer cell motility, migration and invasive. Together, these results demonstrate that TMEM116 is a critical integrator of oncogenic signaling in cancer metastasis.

FGFR3 – a Central Player in Bladder Cancer Pathogenesis?

The identification of mutations in FGFR3 in bladder tumors in 1999 led to major interest in this receptor and during the subsequent 20 years much has been learnt about the mutational profiles found in bladder cancer, the phenotypes associated with these and the potential of this mutated protein as a target for therapy. Based on mutational and expression data, it is estimated that >80% of non-muscle-invasive bladder cancers (NMIBC) and ∼40% of muscle-invasive bladder cancers (MIBC) have upregulated FGFR3 signalling, and these frequencies are likely to be even higher if alternative splicing of the receptor, expression of ligands and changes in regulatory mechanisms are taken into account. Major efforts by the pharmaceutical industry have led to development of a range of agents targeting FGFR3 and other FGF receptors. Several of these have entered clinical trials, and some have presented very encouraging early results in advanced bladder cancer. Recent reviews have summarised the drugs and related clinical trials in this area. This review will summarise what is known about the effects of FGFR3 and its mutant forms in normal urothelium and bladder tumors, will suggest when and how this protein contributes to urothelial cancer pathogenesis and will highlight areas that may benefit from further study.

Cytotoxicity and genotoxicity assays of halobenzoquinones disinfection byproducts using different human cell lines

Recently, halobenzoquinones (HBQs) disinfection byproducts, including 2,6-dichloro-1, 4-benzoquinone (DCBQ), 2,6-dichloro-3-methyl-1, 4-benzoquinone (DCMBQ), 2,3,6-trichloro-1, 4-benzoquinone (TCBQ), and 2,6-dibromobenzoquinone (DBBQ), have been of increasing concern due to their reported ability to induce oxidative damage, and thus genotoxicity. However, data on the risk of genotoxicity due to chromosomal damage by HBQs are still scarce. Here, the cytotoxicity and genotoxicity of the four HBQs were assessed using human cell lines (bladder cancer 5637 cells, colon carcinoma Caco-2 cells, and gastric MGC-803 cells). The four HBQs exhibited significant concentration-response relationships in all the three cell lines. Cytotoxicity of DCBQ, DCMBQ, TCBQ, and DBBQ, represented by the 50% concentration of inhibition (IC₅₀ ) values, were 80.8-99.5, 41.0-57.6, 122.1-146.6, and 86.9-93.8 μM, respectively. The lowest effective concentrations for cellular micronuclei induction in the cell lines by DCBQ, DCMBQ, TCBQ, and DBBQ were 50-75, 20-41.5, 87.4-100, and 50 μM, respectively. 5637 and Caco-2 cells were more sensitive to the cytotoxic and genotoxic effects of HBQs than MGC-803 cells. These results show that HBQs can induce chromosomal damage; DCMBQ induced the highest cytotoxicity and genotoxicity in all the cell lines, and TCBQ caused the least toxicity.

ΔNp63 transcript loss in bladder cancer constitutes an independent molecular predictor of TaT1 patients post-treatment relapse and progression

PURPOSE

Bladder cancer represents a major cause of malignancy-related morbidity and the most expensive per-patient-to-treat cancer, due to the lifelong surveillance of the patients. Accurate disease prognosis is essential in establishing personalized treatment decisions; yet optimum tools for precise risk stratification remain a competing task. In the present study, we have performed the complete evaluation of TP63 clinical significance in improving disease prognosis.

METHODS

The levels of ΔNp63 and TAp63 transcripts of TP63 were quantified in 342 bladder tissue specimens of our screening cohort (n = 182). Hedegaard et al. (Cancer Cell 30:27-42. doi:10.1016/j.ccell.2016.05.004, 2016) (n = 476) and TCGA provisional (n = 413) were used as validation cohorts for NMIBC and MIBC, respectively. Survival analysis was performed using recurrence and progression for NMIBC or mortality for MIBC as endpoint events. Bootstrap analysis was performed for internal validation, while decision curve analysis was used for the evaluation of the clinical net benefit on disease prognosis.

RESULTS

ΔNp63 was significantly expressed in bladder tissues, and was found to be over-expressed in bladder tumors. Interestingly, reduced ΔNp63 levels were correlated with muscle-invasive disease, high-grade tumors and high-EORTC-risk NMIBC patients. Moreover, ΔNp63 loss was independently associated with higher risk for NMIBC relapse (HR = 2.730; p = 0.007) and progression (HR = 7.757; p = 0.016). Hedegaard et al. and TCGA validation cohorts confirmed our findings. Finally, multivariate models combining ΔΝp63 loss with established prognostic markers led to a superior clinical benefit for NMIBC prognosis and risk stratification.

CONCLUSIONS

ΔΝp63 loss is associated with adverse outcome of NMIBC resulting in superior prediction of NMIBC early relapse and progression.

WNT/β-catenin signaling in urothelial carcinoma of bladder

Urothelial carcinoma of bladder is the second most prevalent genitourinary disease. It is a highly heterogeneous disease as it represents a spectrum of neoplasms, including non-muscle invasive bladder cancer (NMIBC), muscle invasive bladder cancer (MIBC) and metastatic lesions. Genome-wide approaches and candidate gene analysis suggest that malignant transformation of the bladder is multifactorial and a multitude of genes are involved in the development of MIBC or NMIBC phenotypes. Wnt signaling is being examined to control and maintain balance between stemness and differentiation in adult stem cell niches. Owing to its participation in urothelial development and maintenance of adult urothelial tissue homeostasis, the components of Wnt signaling are reported as an important diagnostic and prognostic markers as well as novel therapeutic targets. Mutations/epigenetic alterations in the key molecules of Wnt/β-catenin canonical pathway have been linked with tumorigenesis, development of drug resistance and enhanced survival. Present review extends our understanding on the functions of key regulatory molecules of canonical Wnt/β-catenin pathway in urothelial tumorigenesis by inducing cancer stem cell phenotype (UCSCs). UCSCs may be responsible for tumor heterogeneity, high recurrence rates and complex biological behavior of bladder cancer. Therefore, understanding the role of UCSCs and the regulatory mechanisms that are responsible for high relapse rates and metastasis could help to develop pathway inhibitors and augment current therapies. Potential implications in the treatment of urothelial carcinoma of bladder by targeting this pathway primarily in UCSCs as well as in bulk tumor population that are responsible for high relapse rates and metastasis may facilitate potential therapeutic avenues and better prognosis.

Hippo kinases regulate cell junctions to inhibit tumor metastasis in response to oxidative stress

Reactive oxygen species (ROS) are key regulators in cell proliferation, survival, tumor initiation and development. However, the role of ROS in tumor metastasis is less clear. Here, we show that oxidative stress inhibited tumor metastasis via activation of Hippo kinase MST1/2, which led to the phosphorylation and nuclear accumulation of FoxO3a, resulting in upregulation of ΔNp63α expression and suppression of cell migration independent of YAP. Strikingly, while loss of MST1 led to and disruption of cell-cell junction exemplified by reduced E-cadherin expression, resulting in scattered cell growth, loss of MST2 led to disruption of cell-matrix adhesion as evidenced by reduced integrin β4, resulting in increased cell migration and tumor metastasis. Furthermore, expression of MST1 and MST2 was down-regulated in human breast carcinoma. Furthermore, oxidative stress inhibited HER2-or PI3K-mediated tumor metastasis via the MST2-FoxO3a-ΔNp63α pathway. Together, these results that this noncanonical Hippo MST2-FoxO3a-ΔNp63α pathway may play a critical role in ROS-mediated regulation of cell migration and tumor metastasis.

C-terminal α Domain of p63 Binds to p300 to Coactivate β-Catenin

TP63 (p63), a member of the tumor suppressor TP53 (p53) gene family, is essential for ectodermal tissue development and suppresses malignant progression of carcinomas. The most abundant isoform, ΔNp63α (referred to as p63), lacks the N-terminal transactivation (TA) domain, and was originally characterized as a dominant-negative type suppressor against p53 family proteins. It also binds to TCF/LEF to inhibit β-catenin. Nevertheless, transcriptional activation by p63 has also been observed in varied systems. To understand the puzzling results, we analyzed the structure–function relationship of p63 in the control of β-catenin-dependent transcription. p63 acted as a suppressor of moderately induced β-catenin. However, when nuclear targeted S33Y β-catenin was applied to cause the maximum enhancer activation, p63 displayed a β-catenin-coactivating function. The DNA-binding domain of p63 and the target sequence facilitated it. Importantly, we newly found that, despite the absence of TA domain, p63 was associated with p300, a general adaptor protein and chromatin modifier causing transcriptional activation. C-terminal α domain of p63 was essential for p300-binding and for the coactivator function. These results were related to endogenous p63-p300 complex formation and Wnt/β-catenin-responsive gene regulation by p63 in squamous cell carcinoma lines. The novel p63-p300 interaction may be involved in positive regulation of gene expression in tissue development and carcinogenesis.

Multifocal Synchronous Upper Urinary Tract Carcinosarcoma (Sarcomatoid Carcinoma) With Rhabdomyoblastic Differentiation

Carcinosarcoma of the upper urinary tract is very rare. In this article, we report a case of upper urinary tract carcinosarcoma with rhabdomyoblastic differentiation showing distinct transition between the epithelial and mesenchymal components confirmed by morphology and immunohistochemistry. An 81-year-old female underwent radical nephroureterectomy under the diagnosis of left ureteral urothelial carcinoma (UC). Multiple invasive tumors showed combined histology with UC and rhabdomyosarcomatous elements (pT2-ureter and pT3-renal pelvis, pN0, u-lt0, ly0, v0, RM0). Each element demonstrated typical epithelial or mesenchymal staining patterns (positive for AE1/AE3 in the former and positive for vimentin and myogenin in the latter). Notably, immunohistochemical transition patterns of GATA-3, p63, SOX2, and myogenin between UC and rhabdomyosarcomatous elements were observed, implying possible involvement of neoplastic stem cells in the process of carcinosarcoma formation. The patient did not receive any adjuvant therapy and eventually succumbed to multiple visceral metastases (lungs and liver) at 11 months postoperatively. No autopsy was performed.

[Expressions of ΔNp63α, DPC4/Smad4 and P21 in cervical squamous cell carcinoma an their clinical significance]

OBJECTIVE

To investigate the expressions of ΔNp63α, DPC4/Smad4 and P21 in cervical squamous cell carcinomas and explore their implications in tumorigenesis, progression and prognosis of the malignancy.

METHODS

The expressions of ΔNp63α, DPC4/Smad4 and P21 were examined with immunohistochemistry in 100 specimens of cervical squamous cell carcinoma, 40 specimens of cervical intraepithelial neoplasia (CIN) and 40 specimens of normal cervical tissues to explore their associations with the occurrence, progression and prognosis of cervical squamous cell carcinoma.

RESULTS

The expressions of ΔNp63α and DPC4/Smad4 decreased and P21 expression increased significantly in the order of normal cervical tissue, CIN and cervical squamous cell carcinoma (P < 0.01), and their expressions were associated with the differentiation, clinical stages and lymph node metastasis of cervical squamous cell carcinoma (P < 0.01). The expression of ΔNp63α was positively correlated with the expression of DPC4/Smad4 (r=0.581, P < 0.05), and they were both negatively correlated with P21 expression (r=-0.449 and -0.254, respectively; P < 0.05). Kaplan-Meier survival analysis showed that patients with cervical squamous cell carcinoma positive for ΔNp63α and DPC4/Smad4 had a significantly higher 5-year survival rate than those negative for ΔNp63α and DPC4/Smad4 (P < 0.001); the patients positive for P21 had a significantly lower 5-year survival rate than the P21-negative patients (P < 0.005).

CONCLUSIONS

The expressions of ΔNp63α, DPC4/Smad4 and P21are related with the differentiation, invasion, lymph node metastasis, pTNM stage and prognosis of in cervical squamous cell carcinomas, suggesting their value as potential markers for prognostic evaluation of patients with cervical squamous cell carcinoma.

Identification of an enhancer region within the TP63/LEPREL1 locus containing genetic variants associated with bladder cancer risk

Purpose

Genome-wide association studies (GWAS) have led to the identification of a bladder cancer susceptibility variant (rs710521) in a non-coding intergenic region between the TP63 and LEPREL1 genes on chromosome 3q28, suggesting a role in the transcriptional regulation of these genes. In this study, we aimed to functionally characterize the 3q28 bladder cancer risk locus.

Methods

Fine-mapping was performed by focusing on the region surrounding rs710521, and variants were prioritized for further experiments using ENCODE regulatory data. The enhancer activity of the identified region was evaluated using dual-luciferase assays. CRISPR/Cas9-mediated deletion of the enhancer region was performed and the effect of this deletion on cell proliferation and gene expression levels was evaluated using CellTiter-Glo and RT-qPCR, respectively.

Results

Fine-mapping of the GWAS signal region led to the identification of twenty SNPs that showed a stronger association with bladder cancer risk than rs710521. Using publicly available data on regulatory elements and sequences, an enhancer region containing the bladder cancer risk variants was identified. Through reporter assays, we found that the presence of the enhancer region significantly increased ΔNTP63 promoter activity in bladder cancer-derived cell lines. CRISPR/Cas9-mediated deletion of the enhancer region reduced the viability of bladder cancer cells by decreasing the expression of ΔNTP63 and p63 target genes.

Conclusions

Taken together, our data show that bladder cancer risk-associated variants on chromosome 3q28 are located in an active enhancer region. Further characterization of the allele-specific activity of the identified enhancer and its target genes may lead to the identification of novel signaling pathways involved in bladder carcinogenesis.

Electronic supplementary material

The online version of this article (10.1007/s13402-018-0393-5) contains supplementary material, which is available to authorized users.

MiR-223-5p works as an oncomiR in vulvar carcinoma by TP63 suppression

MiR-223-5p has been previously mentioned to be associated with tumor metastasis in HPV negative vulvar carcinomas, such as in several other tumor types. In the present study, we hypothesized that this microRNA would be important in vulvar cancer carcinogenesis and progression. To investigate this, we artificially mimicked miR-223-5p expression in a cell line derived from lymph node metastasis of vulvar carcinoma (SW962) and performed in vitro assays. As results, lower cell proliferation (p < 0.01) and migration (p < 0.001) were observed when miR-223-5p was overexpressed. In contrast, increased invasive potential of these cells was verified (p < 0.004). In silico search indicated that miR-223-5p targets TP63, member of the TP53 family of proteins, largely described with importance in vulvar cancer. We experimentally demonstrated that this microRNA is capable to decrease levels of p63 at both mRNA and protein levels (p < 0.001, and p < 0.0001; respectively). Also, a significant inverse correlation was observed between miR-223-5p and p63 expressions in tumors from patients (p = 0.0365). Furthermore, low p63 protein expression was correlated with deeper tumor invasion (p = 0.0491) and lower patient overall survival (p = 0.0494). Our study points out miR-223-5p overexpression as a putative pathological mechanism of tumor invasion and a promising therapeutic target and highlights the importance of both miR-223-5p and p63 as prognostic factors in vulvar cancer. Also, it is plausible that the evaluation of p63 expression in vulvar cancer at the biopsy level may bring important contribution on prognostic establishment and in elaborating better surgical approaches for vulvar cancer patients.

p63 expression is a prognostic factor in colorectal cancer

p63 is highly expressed in some malignant tumors and is associated with tumorigenesis, invasion and metastasis. The aim of our study was to evaluate the clinical significance of p63 in colorectal cancer (CRC). p63 expression was detected by immunohistochemistry in 66 CRC patients. Correlations between p63 expression and clinicopathological factors, progression-free survival (PFS) and overall survival (OS) were analyzed. Among the 66 CRC cases, 31 cases (47%) exhibited a high score of p63 expression, while 35 cases (53%) were marked with a low score. The p63 level correlated with peritumoral deposits (p=0.021). The 5-year OS rates in the low p63 score and high p63 score groups were, respectively, 49% and 74% (p<0.001). The 5-year PFS rates in the low p63 score and high p63 score groups were, respectively, 44% and 71% (p<0.001). Univariate analysis revealed that p63 expression was correlated with OS and PFS. Multivariate analysis suggested that p63 expression was an independent prognostic factor for OS (p=0.035). In conclusion, p63 was negatively correlated with peritumoral deposits and positively associated with OS and PFS in CRC. The data suggest that p63 is a potential prognostic factor for CRC.

Chemomechanically engineered 3D organotypic platforms of bladder cancer dormancy and reactivation

Tumors undergo periods of dormancy followed by reactivation leading to metastatic disease. Arrest in the G0/G1 phase of the cell cycle and resistance to chemotherapeutic drugs are key hallmarks of dormant tumor cells. Here, we describe a 3D platform of bladder cancer cell dormancy and reactivation facilitated by a novel aminoglycoside-derived hydrogel, Amikagel. These 3D dormant tumor microenvironments (3D-DTMs) were arrested in the G0/G1 phase and were highly resistant to anti-proliferative drugs. Inhibition of targets in the cellular protein production machinery led to induction of endoplasmic reticulum (ER) stress and complete ablation of 3D-DTMs. Nanoparticle-mediated calcium delivery significantly accelerated ER stress-mediated 3D-DTM death. Transfer of 3D-DTMs onto weaker and adhesive Amikagels resulted in selective reactivation of a sub-population of N-cadherin deficient cells from dormancy. Whole-transcriptome analyses further indicated key biochemical differences between dormant and proliferative cancer cells. Taken together, our results indicate that 3D bladder cancer microenvironments of dormancy and reactivation can facilitate fundamental advances and novel drug discovery in cancer.

ΔNp63α is a common inhibitory target in oncogenic PI3K/Ras/Her2-induced cell motility and tumor metastasis

Activation of phosphatidylinositol 3 kinase (PI3K), Ras, and Her2 signaling plays a critical role in cancer development. Hotspot constitutive activating mutations in oncogenes, such as PIK3CA encoding the p110α catalytic subunit or RAS, as well as overexpression of Her2, are frequently found in human tumors and cancers. It has been well established that activation of these oncogenes profoundly promotes tumor metastasis, whereas decreased expression of ΔNp63α, the major protein isoform of the p53-related p63 expressed in epithelial cells, has been associated with cancer metastasis. In this study, we demonstrate that hotspot oncogenic mutations on PIK3CA and RAS, including p110α^H1047R, K-Ras^G12V, and H-Ras^G12V, as well as activation of Her2, all led to suppression of ΔNp63α expression via Akt-fork-head transcription factor 3a (Akt-FOXO3a) signaling, resulting in increased cell motility and tumor metastasis. Expression of ΔNp63α effectively reversed p110α^H1047R-, K-Ras^G12V-, H-Ras^G12V-, or Her2-induced cell motility in vitro and tumor metastasis in mouse models. We show that ΔNp63α was a direct FOXO3a transcriptional target and that expression of FOXO3a and ΔNp63α was correlated in human cancer biopsy samples. Together, these results demonstrate that ΔNp63α is a common inhibitory target of oncogenic PI3K, Ras, and Her2, and that ΔNp63α may function as a critical integrator of oncogenic signaling in cancer metastasis.

Epithelial-mesenchymal transition promotes SOX2 and NANOG expression in bladder cancer

Bladder cancer is the most common malignant tumor of the urothelium and is classified into non-muscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC). Stemness markers such as SOX2 and NANOG are frequently overexpressed in various aggressive cancers, including MIBC; epithelial-mesenchymal transition (EMT) has been proposed as a potential trigger of stemness in cancers. To determine whether cancer stemness is acquired via EMT in bladder cancer, we studied the effect of EMT on the expression of SOX2 and NANOG in bladder cancer cell lines. We also analyzed their expression in clinical tissue samples. Our results revealed that a potent EMT inducer (transforming growth factor β1) reduced the expression of the epithelial marker E-cadherin and increased expression of both SOX2 and NANOG in epithelial-type bladder cancer cells. As for clinical bladder cancer samples, in NMIBC, E-cadherin expression was slightly diminished, and the expression of both SOX2 and NANOG was negligible. In contrast, in MIBC, E-cadherin expression was highly and heterogeneously diminished, while the expression of both SOX2 and NANOG was increased. We also noticed that either E-cadherin or SOX2 (or NANOG) was expressed (ie, in a manner exclusive of each other). In addition, the concentration of E-cadherin showed a significant negative correlation with tumor grade and stage, while expression of SOX2 and NANOG positively correlated with those clinicopathological parameters. These findings suggest that EMT promotes stemness of bladder cancer cells, contributing to tumor aggressiveness. This EMT-cancer stemness axis may also play an important role in the pathogenesis of NMIBC and MIBC.Laboratory Investigation advance online publication, 27 February 2017; doi:10.1038/labinvest.2017.17.

ΔNp63α expression induces loss of cell adhesion in triple-negative breast cancer cells

Background

p63, a member of the p53 protein family, plays key roles in epithelial development and carcinogenesis. In breast cancer, p63 expression has been found predominantly in basal-A (epithelial-type) triple-negative breast carcinomas (TNBC). To investigate the functional role of p63 in basal-A TNBC, we created MDA-MB-468 cell lines with inducible expression of the two major N-terminal p63 isoforms, TAp63α and ∆Np63α.

Results

TAp63α did not have significant effect on gene expression profile and cell phenotype, whilst the main effect of ΔNp63α was reduction of cell adhesion. Gene expression profiling revealed genes involved in cell adhesion and migration whose expression relies on overexpression of ΔNp63α. Reduced cell adhesion also led to decreased cell proliferation in vitro and in vivo. Similar data were obtained in another basal-A cell line, BT-20, but not in BT-549 basal-B (mesenchymal-like) TNBC cells.

Conclusions

In basal-A TNBC cells, ∆Np63α has much stronger effects on gene expression than TAp63α. Although p63 is mentioned mostly in connection with breast cell differentiation and stem cell regulation, we showed that a major effect of p63 is regulation of cell adhesion, a process important in metastasis and invasion of tumour cells. That this effect is not seen in mesenchymal-type TNBC cells suggests lineage-dependent functions, mirroring the expression of ∆Np63α in primary human breast cancers.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2808-x) contains supplementary material, which is available to authorized users.

Dynamic Change in p63 Protein Expression during Implantation of Urothelial Cancer Clusters

Although the dissemination of urothelial cancer cells is supposed to be a major cause of the multicentricity of urothelial tumors, the mechanism of implantation has not been well investigated. Here, we found that cancer cell clusters from the urine of patients with urothelial cancer retain the ability to survive, grow, and adhere. By using cell lines and primary cells collected from multiple patients, we demonstrate that △ Np63α protein in cancer cell clusters was rapidly decreased through proteasomal degradation when clusters were attached to the matrix, leading to downregulation of E-cadherin and upregulation of N-cadherin. Decreased △ Np63α protein level in urothelial cancer cell clusters was involved in the clearance of the urothelium. Our data provide the first evidence that clusters of urothelial cancer cells exhibit dynamic changes in △ Np63α expression during attachment to the matrix, and decreased △ Np63α protein plays a critical role in the interaction between cancer cell clusters and the urothelium. Thus, because △ Np63α might be involved in the process of intraluminal dissemination of urothelial cancer cells, blocking the degradation of △ Np63α could be a target of therapy to prevent the dissemination of urothelial cancer.

p63 controls cell migration and invasion by transcriptional regulation of MTSS1

Metastasis is a multistep cell-biological process, which is orchestrated by many factors, including metastasis activators and suppressors. Metastasis Suppressor 1 (MTSS1) was originally identified as a metastasis suppressor protein whose expression is lost in metastatic bladder and prostate carcinomas. However, recent findings indicate that MTSS1 acts as oncogene and pro-migratory factor in melanoma tumors. Here, we identify and characterized a molecular mechanism controlling MTSS1 expression, which impinges on a pro-tumorigenic role of MTSS1 in breast tumors. We found that in normal and in cancer cell lines ΔNp63 is able to drive the expression of MTSS1 by binding to a p63-binding responsive element localized in the MTSS1 locus. We reported that ΔNp63 is able to drive the migration of breast tumor cells by inducing the expression of MTSS1. Notably, in three human breast tumors data sets the MTSS1/p63 co-expression is a negative prognostic factor on patient survival, suggesting that the MTSS1/p63 axis might be functionally important to regulate breast tumor progression.

ΔNp63 expression is a protective factor of progression in clinical high grade T1 bladder cancer

PURPOSE

Several risk factors have been claimed to predict the progression of clinically high grade T1 bladder tumors. However, these factors are not specific enough to define which patients should be treated immediately with radical cystectomy. Therefore, it is critical to identify molecular markers that can help provide individualized, risk stratified decision making. Our main goal was to evaluate the role of total p63, p53 and ΔNp63 expression in cases of clinically high grade T1 bladder cancer progression.

MATERIALS AND METHODS

Total p63, p53 and ΔNp63 expression was analyzed by immunohistochemistry in 134 clinically high grade T1 tumors. We assessed clinical progression to muscle invasive disease or radical cystectomy as a patient outcome end point. Survival analysis was done for recurrence-free, progression-free, disease specific and overall survival.

RESULTS

A total of 132 patients (98.5%) underwent repeat transurethral resection. Cases of early progression (less than 3 months) were excluded from study to avoid under staging. Of the tumors 90 (67.2%) showed ΔNp63 expression loss. During a median followup of 62.1 months 19 patients (14.2%) progressed to muscle invasive disease. The progression rate was 21.1% in patients with tumors characterized by ΔNp63 loss but no progression was observed in those with tumors with ΔNp63 expression (p <0.001). There was no difference in the number of patients who underwent repeat transurethral resection, had associated carcinoma in situ, showed lymphovascular invasion or received followup intravesical bacillus Calmette-Guérin courses.

CONCLUSIONS

ΔNp63 expression is a favorable prognostic factor in clinically high grade T1 bladder cancer. This marker identifies patients at low risk for progression who could benefit from conservative therapy with transurethral bladder tumor resection and bacillus Calmette-Guérin, avoiding over treatment with immediate radical cystectomy.

Role of vitamin D3 in modulation of ΔNp63α expression during UVB induced tumor formation in SKH-1 mice

ΔNp63α, a proto-oncogene, is up-regulated in non-melanoma skin cancers and directly regulates the expression of both Vitamin D receptor (VDR) and phosphatase and tensin homologue deleted on chromosome ten (PTEN). Since ΔNp63α has been shown to inhibit cell invasion via regulation of VDR, we wanted to determine whether dietary Vitamin D₃ protected against UVB induced tumor formation in SKH-1 mice, a model for squamous cell carcinoma development. We examined whether there was a correlation between dietary Vitamin D₃ and ΔNp63α, VDR or PTEN expression in vivo in SKH-1 mice chronically exposed to UVB radiation and fed chow containing increasing concentrations of dietary Vitamin D₃. Although we observed differential effects of the Vitamin D₃ diet on ΔNp63α and VDR expression in chronically irradiated normal mouse skin as well as UVB induced tumors, Vitamin D₃ had little effect on PTEN expression in vivo. While low-grade papillomas in mice exposed to UV and fed normal chow displayed increased levels of ΔNp63α, expression of both ΔNp63α and VDR was reduced in invasive tumors. Interestingly, in mice fed high Vitamin D₃ chow, elevated levels of ΔNp63α were observed in both local and invasive tumors but not in normal skin suggesting that oral supplementation with Vitamin D₃ may increase the proliferative potential of skin tumors by increasing ΔNp63α levels.

ΔNp63α activates CD82 metastasis suppressor to inhibit cancer cell invasion

P63 is a p53 family member involved in multiple facets of biology, including embryonic development, cell proliferation, differentiation, survival, apoptosis, senescence and aging. The p63 gene encodes multiple protein isoforms either with (TAp63) or without (ΔNp63) the N-terminal transactivation domain. Amounting evidence suggests that p63 can function as a tumor suppressor, yet the precise molecular mechanisms, and particularly the specific roles of TAp63 and ΔNp63 in cancer progression, are still largely unclear. Here, we demonstrated that ΔNp63α, the predominant isoform expressed in epithelial cells and squamous cell carcinomas, inhibits cell invasion. Affymetrix gene expression profiling, combined with gain- and loss-of-function analyses and chromatin immunoprecipitation, indicated that cluster of differentiation 82 (CD82), a documented metastasis suppressor, is a direct transcriptional target of ΔNp63α. Expression of ΔNp63α inhibited outgrowth in Matrigel and cancer cell invasion, which was largely reversed by specific ablation of CD82. Conversely, ΔNp63α knockdown led to increased cell invasion, which was reversed by ectopic expression of CD82. Moreover, inhibition of glycogen synthase kinase-3β (GSK3β) by either pharmacological inhibitors or by RNA interference resulted in the downregulation of ΔNp63α and CD82 expression, concomitant with increased cell invasion, independently of β-catenin. Furthermore, decreased expression of p63 and CD82 is correlated with cancer progression. Taken together, this study reveals that ΔNp63α upregulates CD82 to inhibit cell invasion, and suggests that GSK3β can regulate cell invasion by modulating the ΔNp63α–CD82 axis.

The utility of p63, p40, and GATA-binding protein 3 immunohistochemistry in diagnosing micropapillary urothelial carcinoma

Micropapillary urothelial carcinoma (MPUC) is an uncommon variant of urothelial carcinoma (UC) with an aggressive clinical course. There have been limited studies on the UC markers GATA-binding protein 3 (GATA3), p63, and p40 in MPUC. Our study investigated the immunoreactivity of these 3 markers in MPUC compared with conventional UC of different grades and stages. Immunohistochemistry was performed on 62 cases of high-grade urothelial carcinoma (HGUC), 16 low-grade urothelial carcinoma (LGUC), and 20 MPUC. p63 expression was strong and diffuse in all LGUC, significantly decreased in high stage and HGUC, and virtually absent in MPUC. p40 expression was decreased in HGUC and markedly decreased in MPUC relative to LGUC. These results suggest that loss of p63 expression in a UC appears to be associated with adverse features--including cases with micropapillary differentiation. Decreased GATA3 expression was seen frequently in high-grade and high-pathologic stage (≥pT2) tumors but was retained in MPUC cases. The findings of retained GATA3 expression in MPUC, which often shows a loss of expression of other urothelial markers such as p63, may be helpful for determining the origin of micropapillary carcinoma of unknown primary. Compared with the traditional markers p63 and p40, GATA3 is the most sensitive marker of conventional UC and MPUC.

ΔNp63α regulates Erk signaling via MKP3 to inhibit cancer metastasis

Reduced expression of the p53 family member p63 has been suggested to play a causative role in cancer metastasis. Here, we show that ΔNp63α, the predominant p63 isoform, plays a major role in regulation of cell migration, invasion and cancer metastasis. We identified mitogen-activated protein (MAP) kinase phosphatase 3 (MKP3) as a downstream target of ΔNp63α that is required for mediating these effects. We show that ΔNp63α regulates extracellular signal-regulated protein kinases 1 and 2 (Erk1/2) activity via MKP3 in both cancer and non-transformed cells. We further show that exogenous ΔNp63α inhibits cell invasion and is dependent on MKP3 upregulation for repression. Conversely, endogenous pan-p63 ablation results in increased cell migration and invasion, which can be reverted by reintroducing the ΔNp63α isoform alone, but not by other isoforms. Interestingly, these effects require Erk2, but not Erk1 expression, and can be rescued by enforced MKP3 expression. Moreover, MKP3 expression is reduced in invasive cancers, and reduced p63 expression increases metastatic frequency in vivo. Taken together, these results suggest an important role for ΔNp63α in preventing cancer metastasis by inhibition of Erk2 signaling via MKP3.

Characterization of specific p63 and p63-N-terminal isoform antibodies and their application for immunohistochemistry

The TP63 gene gives rise to protein isoforms with different properties and functions due to the presence (TAp63) or absence (ΔNp63) of an N-terminal p53-like transactivation domain. Immunohistochemistry for p63 has clinical value for certain tumour types, but investigations have been hampered by a lack of well characterized antibodies and the inability to discriminate between these N-terminal isoforms with opposite functional properties. We have extensively characterized a series of monoclonal antibodies to recombinant human TAp63 and two commercial p63 monoclonals by Western blot, immunostaining and phage display epitope mapping. Twenty-eight of 29 (96.6 %) novel monoclonals that recognized all p63 isoforms showed substantial cross-reactivity with p73, as did the commercial antibody, 4A4. One novel clone, PANp63-6.1, showed slight cross-reaction with p73 by Western blotting but not immunohistochemistry and the SFI-6 monoclonal did not cross-react with p73 or p53. Phage display revealed that the PANp63-6.1 epitope has one amino acid difference between p63 and p73, the 4A4 epitope is identical in both, whereas the SFI-6 epitope is unique to p63, accounting for these findings. We also produced and characterized a TAp63-specific clone that does not recognize p53 or p73, and we prepared polyclonal sera specific for ΔNp63 isoforms. Immunohistochemistry demonstrated that TAp63 is expressed in a variety of epithelial and other cell types during development, often in a converse pattern to ΔNp63, but has a very limited expression in normal adult tissues and is independent of ΔNp63. TAp63 was expressed in 17.6 % of squamous cancers of cervix that expressed p63, unlike normal cervix where TAp63 was not expressed. TAp63 did not associate with proliferative index, but cervical carcinomas with TAp63 expression showed improved survival. These data highlight the need for rigorous antibody characterization and indicate that p63-isoform identification may improve the clinical value of p63 expression analyses.

Role of p63 in Development, Tumorigenesis and Cancer Progression

The p53-related protein p63 has pleiotropic functions, including cell proliferation, survival, apoptosis, differentiation, senescence, and aging. The p63 gene is expressed as multiple isoforms that either contain an N-terminal p53-homologous transactivation domain (TAp63) or that lack this domain (ΔNp63). Multiple studies have demonstrated that p63 plays a crucial role in stratified epithelial development, and have shown the importance of p63 for maintaining proliferation potential, inducing differentiation, and preventing senescence. Additionally, much research focuses on the role of p63 in cancer progression. Clinical evidence suggests that p63 may play a role in inhibiting metastasis. Similarly, genetic mice models together with cell culture data strongly indicate that p63 deficiency may be a causative factor for metastatic spread. Moreover, the role of p63 in cancer metastasis has been shown to be greatly related to the ability of mutant p53 to promote cancer malignancy. However, there is still much confusion as to what the role of each specific isoform is. In this review, we highlight some of the major findings in the current literature regarding the role of specific p63 isoforms in development, tumorigenesis, and particularly in cancer metastasis.

Potential role of Hsp90 inhibitors in overcoming cisplatin resistance of bladder cancer-initiating cells

For metastatic bladder cancer patients, systemic cisplatin (CDDP)-based combination chemotherapy is the first-line choice of treatment. Although up to 70% of advanced bladder cancer patients initially show good tumor response to this form of combination chemotherapy, over 90% of good responders relapse and eventually die of the disease. According to the cancer stem cell theory, this phenomenon is attributable to the re-growth of bladder cancer-initiating cells (BCICs) that have survived chemotherapy. In this study, the authors have isolated BCICs from cultured human bladder cancer cells to analyze their sensitivity to CDDP and to investigate whether heat-shock protein 90 (Hsp90) inhibitors potentiate the cytotoxicity of CDDP on BCICs. First, the authors have confirmed that a CD44+ subpopulation of 5637 cells met the requirements to be considered tumor-initiating cells. These BCICs were more resistant to CDDP and exhibited more activity in the Akt and ERK oncogenic signaling pathways when compared with their CD44- counterparts. The Hsp90 inhibitor 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin (17-DMAG), which simultaneously inactivated both Akt and ERK signaling at noncytocidal concentrations, synergistically potentiated the cytotoxicity of CDDP against BCICs by enhancing CDDP-induced apoptosis in vitro. The potentiating effect of 17-DMAG was more effective than a combination of the two inhibitors specific for the Akt and ERK pathways. Finally, the authors have confirmed that, though human BCIC xenografts exhibited resistance to a single administration of CDDP and the Hsp90 inhibitor 17-(allylamino)-17-demethoxygeldanamycin (17-AAG), 17-AAG sensitized them to CDDP in a mouse model. These data encourage clinical trials of Hsp90 inhibitors as they may improve therapeutic outcomes of CDDP-based combination chemotherapy against advanced bladder cancer.

DeltaNp63alpha-mediated induction of epidermal growth factor receptor promotes pancreatic cancer cell growth and chemoresistance

Pancreatic ductal adenocarcinoma (PDAC) is highly resistant to current chemotherapy regimens, in part due to alterations in the p53 tumor suppressor pathway. p53 homolog p63 is a transcription factor essential for the development and differentiation of epithelial surfaces. However its function in cancer is controversial and its role in PDAC is not known. We discovered that ΔNp63α was the predominantly expressed p63 variant in pancreatic cancer cell lines. ΔNp63α protein and mRNA levels were high in T3M4, BxPC3 and COLO-357 pancreatic cancer cells and low in ASPC-1 and PANC-1 cells. Overexpression of ΔNp63α in PANC-1 cells and shRNA-mediated knockdown in T3M4 cells indicated that ΔNp63α promoted anchorage-dependent and -independent growth, motility and invasion, and enhanced resistance to cisplatin-induced apoptosis. Epidermal growth factor receptor (EGFR) signaling pathways contribute to the biological aggressiveness of PDAC, and we found that the motogenic effects of ΔNp63α were augmented in presence of EGF. Ectopic expression of ΔNp63α resulted in upregulation of EGFR and β1-integrin in PANC-1 cells. Conversely, ΔNp63α knockdown had an opposite effect in T3M4 cells. ΔNp63α potentiated EGF-mediated activation of ERK, Akt and JNK signaling. Chromatin immunoprecipitation and functional reporter assays demonstrated that ΔNp63α activated EGFR transcription. 14-3-3σ transcription was also positively regulated by ΔNp63α and we have previously shown that 14-3-3σ contributes to chemoresistance in pancreatic cancer cell lines. Conversely, shRNA-mediated knockdown of 14-3-3σ led to abrogation of the ΔNp63α effects on cell proliferation and invasion. Thus, p53 homolog ΔNp63α enhances the oncogenic potential of pancreatic cancer cells through trans-activation of EGFR and 14-3-3σ.

p63 is a suppressor of tumorigenesis and metastasis interacting with mutant p53

p53 mutations, occurring in two-thirds of all human cancers, confer a gain of function phenotype, including the ability to form metastasis, the determining feature in the prognosis of most human cancer. This effect seems mediated at least partially by its ability to physically interact with p63, thus affecting a cell invasion pathway, and accordingly, p63 is deregulated in human cancers. In addition, p63, as an 'epithelial organizer', directly impinges on epidermal mesenchimal transition, stemness, senescence, cell death and cell cycle arrest, all determinant in cancer, and thus p63 affects chemosensitivity and chemoresistance. This demonstrates an important role for p63 in cancer development and its progression, and the aim of this review is to set this new evidence that links p63 to metastasis within the context of the long conserved other functions of p63.

Distinct expression profiles of p63 variants during urothelial development and bladder cancer progression

The TP63 gene, a member of the TP53 tumor suppressor gene family, can be expressed as at least six isoforms due to alternative promoter use and alternative splicing. The lack of p63 isoform-specific antibodies has limited the analysis of the biological significance of p63. We report a novel set of well-defined antibodies to examine p63 isoforms in mouse and human urothelium during embryogenesis and tumor progression, respectively. We provide evidence that basal and intermediate urothelial cells express p63 isoforms, with the TAp63 variant the first to be detected during development, whereas umbrella cells are characterized by a p63-negative phenotype. Notably, we report that p63-null mice develop a bladder with an abnormal urothelium, constituted by a single layer of cells that express uroplakin II and low molecular weight cytokeratins, consistent with an umbrella cell phenotype. Finally, analysis of 202 human bladder carcinomas revealed a new categorization of invasive tumors into basal-like (positive for ΔNp63 and high molecular weight cytokeratins and negative for low molecular weight cytokeratins) versus luminal-like (negative for ΔNp63 and high molecular weight cytokeratins and positive for low molecular weight cytokeratins) phenotypes, with ΔNp63 expression associated with an aggressive clinical course and poor prognosis. This study highlights the relevance of p63 isoforms in both urothelial development and bladder carcinoma progression, with ΔNp63 acting as an oncogene in certain invasive bladder tumors.

Role of p63 in cancer development

Since their initial identification p53 homologues p63 and p73 have been expected to play a role in cancer development due to their close homology to p53, notoriously one of the most mutated genes in cancer. However soon after their discovery the awareness that these genes were rarely mutated in cancer seemed to indicate that they did not play a role in its development. However a large number of data collected in the following years indicated that altered expression rather than mutation could be found in different neoplasia and play a role in its biology. In particular p63 due to its fundamental role in epithelial development seems to play a role in a number of tumors of epithelial origin. In this review we summarize some of the evidence linking p63 to carcinogenesis.

Induction of ΔNp63 by the newly identified keratinocyte-specific transforming growth factor β Signaling Pathway with Smad2 and IκB Kinase α in squamous cell carcinoma

The expression of p63 (TP63/p51) occurs in the basal cells of stratified epithelia and is strongly enhanced at the early stages of squamous cell carcinomas (SCCs) of the head and neck, skin, cervix, and others. We analyzed a promoter/enhancer region (2kΔN) that drives the predominant expression of ΔNp63 for sensitivity to Smad signaling pathways. Reporter assays in HepG2 cells showed a moderate activation of 2kΔN by Smad2 and IκB kinase α (IKKα), partners of the newly identified keratinocyte-specific transforming growth factor β (TGF-β) signaling, but not by other Smad molecules. In A431 cells, 2kΔN was activated by Smad2 and IKKα, for which a Smad binding element (SMD2) at -204 was essential. Binding of Smad2 to the chromosomal SMD2 site was detectable. The association of Smad2 with IKKα was evident in the nucleus of A431, accounting for the enhancement of ΔNp63 expression by TGF-β. Moreover, both ΔNp63 and IKKα were necessary to maintain the noninvasive phenotype of this cell line. FaDu, an invasive, Smad4-deficient SCC, also allowed 2kΔN transactivation by transfected Smad2 in the presence of endogenous IKKα. Reflecting the lack of chromosomal SMD2-Smad2 association and the absence of nuclear IKKα, however, endogenous ΔNp63 was not controlled by TGF-β or IKKα in FaDu. SCC tissue arrays showed nuclear accumulation of IKKα and p63 intensification in well-differentiated noninvasive lesions. This study indicates that p63 is a target gene of the proposed keratinocyte-specific TGF-β signal pathway for suppression of the malignant conversion of SCC.

A comparison of primary oesophageal squamous epithelial cells with HET-1A in organotypic culture

BACKGROUND INFORMATION

Carcinoma of the oesophagus is the sixth leading cause of cancer death in the western world and is associated with a 5-year survival of less than 15%. Recent evidence suggests that stromal-epithelial interactions are fundamental in carcinogenesis. The advent of co-culture techniques permits the investigation of cross-talk between the stroma and epithelium in a physiological setting. We have characterized a histologically representative oesophageal organotypic model and have used it to compare the most commonly used squamous oesophageal cell line, HET-1A, with primary oesophageal squamous cells for use in studies of the oesophageal epithelium in vitro.

RESULTS

When grown in an organotypic culture with normal fibroblasts, the oesophageal carcinoma cell lines OE21 (squamous) and OE19 (adenocarcinoma) morphologically resembled the tumour of origin with evidence of stromal invasion and mucus production, respectively. However, HET-1A cells, which were derived from normal squamous oesophageal cells, appeared dysplastic and failed to display evidence of squamous differentiation. By comparison with primary oesophageal epithelial cells, the HET-1A cells were highly proliferative and did not express the epithelial markers E-cadherin or CK5/6 (casein kinase 5/6), or the stratified epithelial marker ΔNp63, but did express the mesenchymal markers vimentin and N-cadherin.

CONCLUSION

Studies of epithelial carcinogenesis will benefit from culture systems which allow manipulation of the stromal and epithelial layers independently. We have developed an organotypic culture using primary oesophageal squamous cells and fibroblasts in which a stratified epithelium with a proliferative basal layer that stains strongly for ΔNp63 develops. This model will be suitable for the study of the molecular events in the development of Barrett's oesophagus. The most commonly used normal oesophageal squamous cell line, HET-1A, does not have the characteristics of normal oesophageal squamous cells and should not be used in models of the normal oesophageal epithelium. Until more representative cell lines are available, future studies in oesophageal cancer will be reliant on the availability and manipulation of primary tissue.

The guardians of the genome (p53, TA-p73, and TA-p63) are regulators of tumor suppressor miRNAs network

The tumor suppressor p53 homologues, TA-p73, and p63 have been shown to function as tumor suppressors. However, how they function as tumor suppressors remains elusive. Here, I propose a number of tumor suppressor pathways that illustrate how the TA-p73 and p63 could function as negative regulators of invasion, metastasis, and cancer stem cells (CSCs) proliferation. Furthermore, I provide molecular insights into how TA-p73 and p63 could function as tumor suppressors. Remarkably, the guardians--p53, p73, and p63--of the genome are in control of most of the known tumor suppressor miRNAs, tumor suppressor genes, and metastasis suppressors by suppressing c-myc through miR-145/let-7/miR-34/TRIM32/PTEN/FBXW7. In particular, p53 and TA-p73/p63 appear to upregulate the expression of (1) tumor suppressor miRNAs, such as let-7, miR-34, miR-15/16a, miR-145, miR-29, miR-26, miR-30, and miR-146a; (2) tumor suppressor genes, such as PTEN, RBs, CDKN1a/b/c, and CDKN2a/b/c/d; (3) metastasis suppressors, such as Raf kinase inhibitory protein, CycG2, and DEC2, and thereby they enlarge their tumor suppressor network to inhibit tumorigenesis, invasion, angiogenesis, migration, metastasis, and CSCs proliferation.