ΔNp63α and microRNAs: leveraging the epithelial-mesenchymal transition

Prognostic Value of P63 Expression in Muscle-Invasive Bladder Cancer and Association with Molecular Subtypes-Preliminary Report

There is an ongoing need for biomarkers that could reliably predict the outcome of BC and that could guide the management of this disease. In this setting, we aimed to explore the prognostic value of the transcription factor P63 in patients with muscle-invasive bladder cancer (MIBC) having undergone radical cystectomy. The correlation between P63 expression and clinicopathological features (tumor stage, nodes involvement, patterns of muscularis propria invasion, papillary architecture, anaplasia, concomitant carcinoma in situ, lymphovascular invasion, perineural invasion, necrosis) and molecular subtyping (basal and luminal type tumors) was tested in 65 radical cystectomy specimens and matched with cancer-specific survival (CSS) and overall survival (OS). P63-negative tumors displayed significantly higher rates of pattern 2 of muscularis propria invasion (50% vs. 14%, p = 0.002) and variant histology (45% vs. 19%, p = 0.022) compared to P63-positive ones. According to the combined expression of CK5/6 and CK20 (Algorithm #1), P63-positive and P63-negative tumors were mostly basal-like and double-negative, respectively (p = 0.004). Using Algorithm #2, based on the combined expression of CK5/6 and GATA3, the vast majority of tumors were luminal overall and in each group (p = 0.003). There was no significant difference in CSS and OS between P63-positive and P63-negative tumors, but the former featured a trend towards longer OS. Though associated with pathological features harboring negative prognostic potential, P63 status as such failed to predict CSS and OS. That said, it may contribute to better molecular subtyping of MIBC.

Dysregulation of delta Np63 alpha in squamous cell carcinoma and its therapeutic targeting

The gene p63 has two isoforms -a full length transactivated isoform (TA) p63 and an amino-terminally truncated isoform, ∆Np63. DeltaNp63 alpha (∆Np63α) is the predominant splice variant of the isoform, ∆Np63 and is expressed in the basal layer of stratified epithelia. ∆Np63α that is normally essential for the epithelial lineage maintenance may be dysregulated in squamous cell carcinomas (SCCs). The pro-tumorigenic or antitumorigenic role of ∆Np63 is a highly contentious arena. ∆Np63α may act as a double-edged sword. It may either promote tumor progression, epithelial-mesenchymal transition, migration, chemoresistance, and immune-inflammatory responses, or inhibit the aforementioned phenomena depending upon cell type and tumor microenvironment. Several signaling pathways, transforming growth factor-β, Wnt and Notch, as well as epigenetic alterations involving microRNAs, and long noncoding RNAs are regulated by ∆Np63α. This review has attempted to provide an in-depth insight into the role of ∆Np63α in the development of SCCs during different stages of tumor formation and how it may be targeted for therapeutic implications.

The p53 Family Members p63 and p73 Roles in the Metastatic Dissemination: Interactions with microRNAs and TGFβ Pathway

TP53 (TP53), p73 (TP73), and p63 (TP63) are members of the p53 transcription factor family, which has many activities spanning from embryonic development through to tumor suppression. The utilization of two promoters and alternative mRNA splicing has been shown to yield numerous isoforms in p53, p63, and p73. TAp73 is thought to mediate apoptosis as a result of nuclear accumulation following chemotherapy-induced DNA damage, according to a number of studies. Overexpression of the nuclear ΔNp63 and ΔNp73 isoforms, on the other hand, suppresses TAp73's pro-apoptotic activity in human malignancies, potentially leading to metastatic spread or inhibition. Another well-known pathway that has been associated to metastatic spread is the TGF pathway. TGFs are a family of structurally related polypeptide growth factors that regulate a variety of cellular functions including cell proliferation, lineage determination, differentiation, motility, adhesion, and cell death, making them significant players in development, homeostasis, and wound repair. Various studies have already identified several interactions between the p53 protein family and the TGFb pathway in the context of tumor growth and metastatic spread, beginning to shed light on this enigmatic intricacy.

The origin of bladder cancer from mucosal field effects

Whole-organ mapping was used to study molecular changes in the evolution of bladder cancer from field effects. We identified more than 100 dysregulated pathways, involving immunity, differentiation, and transformation, as initiators of carcinogenesis. Dysregulation of interleukins signified the involvement of inflammation in the incipient phases of the process. An aberrant methylation/expression of multiple HOX genes signified dysregulation of the differentiation program. We identified three types of mutations based on their geographic distribution. The most common were mutations restricted to individual mucosal samples that targeted uroprogenitor cells. Two types of mutations were associated with clonal expansion and involved large areas of mucosa. The α mutations occurred at low frequencies while the β mutations increased in frequency with disease progression. Modeling revealed that bladder carcinogenesis spans 10-15 years and can be divided into dormant and progressive phases. The progressive phase lasted 1-2 years and was driven by β mutations.

MicroRNA31 and MMP-1 contribute to the differentiated pathway of invasion -with enhanced epithelial-to-mesenchymal transition- in squamous cell carcinoma of the skin

Epithelial to mesenchymal transition (EMT) is an important mechanism of invasion in cutaneous squamous cell carcinomas (cSCCs) and has been found to be enhanced in tumors originated from actinic keratosis with transformation limited to the basal epithelial layer -differentiated pathway-, compared to cases with invasion subsequent to complete epidermal transformation -classical pathway-. Several microRNAs and proteins can contribute to EMT modulation in cSCCs. MicroRNA21 and microRNA31 are involved in posttranscriptional regulation of protein expression and could play a relevant role in EMT and cSCC progression. Throughout the EMT process upregulation of matrix metalloproteinases (MMPs) enhances invasiveness and MMP-1 and MMP-3 contribute to local invasion, angiogenesis and metastasis in cSCCs. Additionally, cSCC development is associated with PTEN loss and NF-κB, NOTCH-1 and p63 activation. The aim of this work is to identify differences in the expression of those molecules between both pathways of cSCCs development. Eight tissue microarrays from 80 consecutive cSCCs were analyzed using LNA-based miRNA in situ hybridization for miRNA21 and miRNA31 evaluation, and immunohistochemistry for MMP-1, MMP-3, PTEN, NOTCH-1, NF-κB, p63 and CD31. Significantly higher expression of miRNA31 (p < 0.0001) and MMP-1 (p = 0.0072) and angiogenesis (p = 0.0199) were found in the differentiated pathway, whereas PTEN loss (p = 0.0430) was more marked in the classical pathway. No significant differences were found for the other markers. Our findings support a contribution of miRNA31 and MMP-1 in the differentiated pathway, associated to EMT and increased microvascularization. The greater PTEN loss in the classical pathway indicate that its relevance in cSCC is not EMT-related.

Regulation of breast cancer metastasis signaling by miRNAs

Despite the decline in death rate from breast cancer and recent advances in targeted therapies and combinations for the treatment of metastatic disease, metastatic breast cancer remains the second leading cause of cancer-associated death in U.S. women. The invasion-metastasis cascade involves a number of steps and multitudes of proteins and signaling molecules. The pathways include invasion, intravasation, circulation, extravasation, infiltration into a distant site to form a metastatic niche, and micrometastasis formation in a new environment. Each of these processes is regulated by changes in gene expression. Noncoding RNAs including microRNAs (miRNAs) are involved in breast cancer tumorigenesis, progression, and metastasis by post-transcriptional regulation of target gene expression. miRNAs can stimulate oncogenesis (oncomiRs), inhibit tumor growth (tumor suppressors or miRsupps), and regulate gene targets in metastasis (metastamiRs). The goal of this review is to summarize some of the key miRNAs that regulate genes and pathways involved in metastatic breast cancer with an emphasis on estrogen receptor α (ERα+) breast cancer. We reviewed the identity, regulation, human breast tumor expression, and reported prognostic significance of miRNAs that have been documented to directly target key genes in pathways, including epithelial-to-mesenchymal transition (EMT) contributing to the metastatic cascade. We critically evaluated the evidence for metastamiRs and their targets and miRNA regulation of metastasis suppressor genes in breast cancer progression and metastasis. It is clear that our understanding of miRNA regulation of targets in metastasis is incomplete.

Independent Validation of Tumor Budding Activity and Cell Nest Size as Determinants of Patient Outcome in Squamous Cell Carcinoma of the Uterine Cervix

A novel 3-tiered grading system that combines tumor budding activity and cell nest size has been found to be highly prognostic in squamous cell carcinomas (SCCs) of various sites, including lung, oral cavity, larynx, hypopharynx, and esophagus. A similar grading system has recently been proposed for SCC of the uterine cervix. In this study, we appraise this grading system in an institutional cohort of cervical SCC to assess its prognostic value in an independent dataset. Our study cohort consisted of 94 consecutive, surgically excised, neoadjuvant therapy-naive cases of SCC of the uterine cervix, stage pT1b or higher. Tumor budding activity and cell nest size were scored on each case, the sum of which formed the basis for assigning a grade in the 3-tiered grading system hereafter referred to as the "tumor budding/nest size" (TBNS) system. As individual variables, both high tumor budding and small nest size were each associated with reduced overall survival (OS), disease-specific survival, and disease-free survival. The full TBNS system was associated with decreased OS, disease-specific survival, and disease-free survival independent of patient age, pathologic stage, and regional lymph node status. TBNS grades 1, 2, and 3 subgroups were clearly distinguishable on multivariate analyses (hazard ratio for OS of 2.06 [95% confidence interval: 0.5-8.42] for grade 2 and 4.58 [95% confidence interval: 1.24-16.87] for grade 3 tumors, relative to their grade 1 counterparts [P=0.035]). Higher grade tumors in the TBNS system were significantly correlated with advanced pathologic stage and lymph node metastasis (P=0.044 and 0.04, respectively). Among the other, potentially prognostic factors, higher pathologic stage, and lymph node metastasis were associated with decreased OS (P<0.001 and 0.004, respectively), whereas keratinization, nuclear size, mitotic count, and World Health Organization (WHO) grade were not. In conclusion, the proposed TBNS grading system is an excellent prognostic indicator that may potentially provide information that is useful in clinical decision-making. Our findings validate the previous study that proposed this system for prognostically stratifying cervical SCC patients. If further confirmed, consideration should be given to routinely adding a TBNS grade to pathologic descriptions of cervical SCC.

Dysregulation of EMT Drives the Progression to Clinically Aggressive Sarcomatoid Bladder Cancer

Sarcomatoid urothelial bladder cancer (SARC) displays a high propensity for distant metastasis and is associated with short survival. We report a comprehensive genomic analysis of 28 cases of SARC and 84 cases of conventional urothelial carcinoma (UC), with the TCGA cohort of 408 muscle-invasive bladder cancers serving as the reference. SARCs show a distinct mutational landscape, with enrichment of TP53, RB1, and PIK3CA mutations. They are related to the basal molecular subtype of conventional UCs and could be divided into epithelial-basal and more clinically aggressive mesenchymal subsets on the basis of TP63 and its target gene expression levels. Other analyses reveal that SARCs are driven by downregulation of homotypic adherence genes and dysregulation of the EMT network, and nearly half exhibit a heavily infiltrated immune phenotype. Our observations have important implications for prognostication and the development of more effective therapies for this highly lethal variant of bladder cancer.

Urothelial-to-Neural Plasticity Drives Progression to Small Cell Bladder Cancer

We report a comprehensive molecular analysis of 34 cases of small cell carcinoma (SCC) and 84 cases of conventional urothelial carcinoma (UC), with The Cancer Genome Atlas cohort of 408 conventional UC bladder cancers used as the reference. SCCs showed mutational landscapes characterized by nearly uniform inactivation of TP53 and were dominated by Sanger mutation signature 3 associated with loss of BRCA1/2 function. SCCs were characterized by downregulation of luminal and basal markers and were referred to as double-negative. Transcriptome analyses indicated that SCCs displayed lineage plasticity driven by a urothelial-to-neural phenotypic switch with a dysregulated epithelial-to-mesenchymal transition network. SCCs were depleted of immune cells, and expressed high levels of the immune checkpoint receptor, adenosine receptor A2A (ADORA2A), which is a potent inhibitor of immune infiltration. Our observations have important implications for the prognostication and development of more effective therapies for this lethal bladder cancer variant.

•

SCCs show TP53/RB1 loss with mutational signature of BRCA1/2 loss of function

•

SCCs are driven by neural phenotypic switch with dysregulated EMT network

•

SCCs show depleted immune phenotype with upregulation of ADORA2A

ΔNp63α suppresses cells invasion by downregulating PKCγ/Rac1 signaling through miR-320a

ΔNp63α, a member of the p53 family of transcription factors, is overexpressed in a number of cancers and plays a role in proliferation, differentiation, migration, and invasion. ΔNp63α has been shown to regulate several microRNAs that are involved in development and cancer. We identified miRNA miR-320a as a positively regulated target of ΔNp63α. Previous studies have shown that miR-320a is downregulated in colorectal cancer and targets the small GTPase Rac1, leading to a reduction in noncanonical WNT signaling and EMT, thereby inhibiting tumor metastasis and invasion. We showed that miR-320a is a direct target of ΔNp63α. Knockdown of ΔNp63α in HaCaT and A431 cells downregulates miR-320a levels and leads to a corresponding elevation in PKCγ transcript and protein levels. Rac1 phosphorylation at Ser71 was increased in the absence of ΔNp63α, whereas overexpression of ΔNp63α reversed S71 phosphorylation of Rac1. Moreover, increased PKCγ levels, Rac1 phosphorylation and cell invasion observed upon knockdown of ΔNp63α was reversed by either overexpressing miR-320a mimic or Rac1 silencing. Finally, silencing PKCγ or treatment with the PKC inhibitor Gö6976 reversed increased Rac1 phosphorylation and cell invasion observed upon silencing ΔNp63α. Taken together, our data suggest that ΔNp63α positively regulates miR-320a, thereby inhibiting PKCγ expression, Rac1 phosphorylation, and cancer invasion.

Plasmacytoid cells in salivary pleomorphic adenoma: an alternative interpretation of their immunohistochemical characteristics highlights function and capability for epithelial-mesenchymal transition

OBJECTIVES

Plasmacytoid cells (PLCs) in salivary pleomorphic adenoma (SPA) are regarded as modified neoplastic myoepithelia and define plasmacytoid myoepithelioma (pMYO). However, histochemically, immunohistochemically and ultrastructurally, PLCs fail to demonstrate frank myogenous properties. Epithelial-mesenchymal transition (EMT) may explain the phenotypes in SPA. Our aim was to evaluate (1) PLCs with accepted or purported myoepithelial and EMT-related markers; and (2) pMYOs for PLAG1 aberrations by using fluorescence in situ hybridization.

STUDY DESIGN

Eight SPAs with or without PLC-predominance and 3 pMYOs were immunohistochemically studied.

RESULTS

PLCs in SPA and pMYO exhibited strong, scattered to diffuse positivity for K7, rare K14 positivity and were mostly negative for α-smooth muscle actin, h-caldesmon, and p63/p40. S100 staining was strong and diffuse, whereas calponin was variable. DOG1 was negative. PLCs in pMYO and PLC-rich SPA exhibited selective or diffuse WT1 and D2-40 immunoreactivity. EMT markers SNAIL/SLUG exhibited strong and variable immunoreactivity in PLCs in contrast to weak or absent E-cadherin expression. SOX10 was diffusely and strongly positive. PLAG1 rearrangement was present in 1 pMYO.

CONCLUSIONS

PLCs mostly fail to express myoepithelial markers; PLCs are neoplastic cells adapting to microenvironmental changes and capable of EMT; and tumors composed solely of PLCs are apparently SPAs depleted of a ductal component.

Molecular Mechanisms of p63-Mediated Squamous Cancer Pathogenesis

The p63 gene is a member of the p53/p63/p73 family of transcription factors and plays a critical role in development and homeostasis of squamous epithelium. p63 is transcribed as multiple isoforms; ΔNp63α, the predominant p63 isoform in stratified squamous epithelium, is localized to the basal cells and is overexpressed in squamous cell cancers of multiple organ sites, including skin, head and neck, and lung. Further, p63 is considered a stem cell marker, and within the epidermis, ΔNp63α directs lineage commitment. ΔNp63α has been implicated in numerous processes of skin biology that impact normal epidermal homeostasis and can contribute to squamous cancer pathogenesis by supporting proliferation and survival with roles in blocking terminal differentiation, apoptosis, and senescence, and influencing adhesion and migration. ΔNp63α overexpression may also influence the tissue microenvironment through remodeling of the extracellular matrix and vasculature, as well as by enhancing cytokine and chemokine secretion to recruit pro-inflammatory infiltrate. This review focuses on the role of ΔNp63α in normal epidermal biology and how dysregulation can contribute to cutaneous squamous cancer development, drawing from knowledge also gained by squamous cancers from other organ sites that share p63 overexpression as a defining feature.

Differential bronchial epithelial response regulated by ΔNp63: a functional understanding of the epithelial shedding found in asthma

Bronchial epithelial cells serve as a physical barrier at the forefront of the immune system. Barrier disruption and an excessive immune response of the bronchial epithelium contribute to the pathophysiology of asthma, a chronic bronchial inflammatory disease. The purpose of this study was to investigate the functional significance of ΔNp63, a p53-like transcription factor expressed by the basal bronchial epithelium. The immunohistochemical expression profile of ΔNp63 was evaluated in human bronchial tissue derived from asthma patients. The role of ΔNp63 in apoptosis inhibition and production of soluble mediators was investigated in vitro with cultured BEAS-2B bronchial epithelial cells using molecular biological analysis. In healthy bronchial tissue, ΔNp63-positive basal epithelial cells were covered with differentiated ΔNp63-negative cells but in the asthmatic airway, ΔNp63-positive cells were directly exposed to the bronchial lumen due to severe epithelial shedding. ΔNp63 regulated bronchial apoptosis in response to Toll-like receptor 3 stimulation. On the other hand, expression of ΔNp63 was modulated by stimulation with trypsin and SLIGKV, protease-activated receptor 2 ligands. Further phenotypic analysis revealed that ΔNp63 controlled the transcriptional expression and protein release of some epithelium-derived proinflammatory cytokines and endogenous protease inhibitors. We conclude that ΔNp63 modulates the bronchial epithelial response to viral infection. At the same time, ΔNp63 expression is influenced by proteases, which are abundant in house dust mites. Therefore, the ΔNp63 axis would be intimately involved in these two major triggers of asthma exacerbations, viral infection and protease overload.

Identification of novel ΔNp63α-regulated miRNAs using an optimized small RNA-Seq analysis pipeline

Advances in high-throughput sequencing have enabled profiling of microRNAs (miRNAs), however, a consensus pipeline for sequencing of small RNAs has not been established. We built and optimized an analysis pipeline using Partek Flow, circumventing the need for analyzing data via scripting languages. Our analysis assessed the effect of alignment reference, normalization method, and statistical model choice on biological data. The pipeline was evaluated using sequencing data from HaCaT cells transfected with either a non-silencing control or siRNA against ΔNp63α, a p53 family member protein which is highly expressed in non-melanoma skin cancer and shown to regulate a number of miRNAs. We posit that 1) alignment and quantification to the miRBase reference provides the most robust quantitation of miRNAs, 2) normalizing sample reads via Trimmed Mean of M-values is the most robust method for accurate downstream analyses, and 3) use of the lognormal with shrinkage statistical model effectively identifies differentially expressed miRNAs. Using our pipeline, we identified previously unrecognized regulation of miRs-149-5p, 18a-5p, 19b-1-5p, 20a-5p, 590-5p, 744-5p and 93-5p by ΔNp63α. Regulation of these miRNAs was validated by RT-qPCR, substantiating our small RNA-Seq pipeline. Further analysis of these miRNAs may provide insight into ΔNp63α's role in cancer progression. By defining the optimal alignment reference, normalization method, and statistical model for analysis of miRNA sequencing data, we have established an analysis pipeline that may be carried out in Partek Flow or at the command line. In this manner, our pipeline circumvents some of the major hurdles encountered during small RNA-Seq analysis.

STAT3, stem cells, cancer stem cells and p63

Signal Transducer and Activator of Transcription 3 (STAT3) is a transcription factor with many important functions in the biology of normal and transformed cells. Its regulation is highly complex as it is involved in signaling pathways in many different cell types and under a wide variety of conditions. Besides other functions, STAT3 is an important regulator of normal stem cells and cancer stem cells. p63 which is a member of the p53 protein family is also involved in these functions and is both physically and functionally connected with STAT3. This review summarizes STAT3 function and regulation, its role in stem cell and cancer stem cell properties and highlights recent reports about its relationship to p63.

miR-373 suppresses gastric cancer metastasis by downregulating vimentin

MicroRNA-373 (miR-373) has been reported to be an oncogene in a number of solid human tumors. However, the role of miR‑373 in gastric cancer has not been completely elucidated and the mechanisms remain unclear. In the present study, we compared miR‑373 expression between clinical gastric cancer tissues and paired non‑tumorous tissues by reverse transcription‑quantitative polymerase chain reaction. The impact of miR‑373 on proliferation, migration and invasion in gastric cancer cells was additionally investigated. Hsa‑miR‑373 mimics were applied to mimic the function of endogenous miR‑373. A colony formation assay and flow cytometry were performed to analyze the proliferation of gastric cancer cells. Wound healing and Transwell invasion assays were employed to detect the migratory and invasive abilities of gastric cancer cells. Western blotting was used to test the expression of epithelial‑mesenchymal transition‑associated proteins. The results demonstrated that the level of miR‑373 in gastric cancer was upregulated compared with paired non‑tumorous tissues. It was confirmed that miR‑373 inhibited the migration and invasion of the gastric cancer cell lines SGC‑7901 and HGC‑27 by downregulating vimentin expression. The results of the present study demonstrated an oncogenic role of miR‑373 in the metastasis of human gastric cancer, and may provide a novel therapeutic strategy for gastric cancer.

MicroRNAs Regulate Thymic Epithelium in Age-Related Thymic Involution via Down- or Upregulation of Transcription Factors

Age-related thymic involution is primarily induced by defects in nonhematopoietic thymic epithelial cells (TECs). It is characterized by dysfunction of multiple transcription factors (TFs), such as p63 and FoxN1, and also involves other TEC-associated regulators, such as Aire. These TFs and regulators are controlled by complicated regulatory networks, in which microRNAs (miRNAs) act as a key player. miRNAs can either directly target the 3'-UTRs (untranslated regions) of the TFs to suppress TF expression or target TF inhibitors to reduce or increase TF inhibitor expression and thereby indirectly enhance or inhibit TF expression. Here, we review the current understanding and recent studies about how miRNAs are involved in age-related thymic involution via regulation of TEC-autonomous TFs. We also discuss potential strategies for targeting miRNAs to rejuvenate age-related declined thymic function.

MicroRNAs regulate the epithelial-mesenchymal transition and influence breast cancer invasion and metastasis

MicroRNAs are small RNA molecules that play a major role in the post-transcriptional regulation of genes and influence the development, differentiation, proliferation, and apoptosis of cells and the development and progression of tumors. The epithelial-mesenchymal transition is a process by which epithelial cells morphologically transform into cells with a mesenchymal phenotype. The epithelial-mesenchymal transition plays a highly important role in tumor invasion and metastasis. Increasing evidence indicates that microRNAs are tightly associated with epithelial-mesenchymal transition regulation in tumor cells. In breast cancer, various microRNA molecules have been identified as epithelial-mesenchymal transition inducers or inhibitors, which, through different mechanisms and signaling pathways, participate in the regulation of breast cancer invasion and metastasis among various biological behaviors. The epithelial-mesenchymal transition-related microRNAs in breast cancer provide valuable molecules for researching cell invasion and metastasis, and they also provide candidate targets that may be significant for the targeted therapy of breast cancer.