Loss of the p53/p63 regulated desmosomal protein Perp promotes tumorigenesis

A Systemic and Integrated Analysis of p63-Driven Regulatory Networks in Mouse Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is the most common malignancy of the oral cavity and is linked to tobacco exposure, alcohol consumption, and human papillomavirus infection. Despite therapeutic advances, a lack of molecular understanding of disease etiology, and delayed diagnoses continue to negatively affect survival. The identification of oncogenic drivers and prognostic biomarkers by leveraging bulk and single-cell RNA-sequencing datasets of OSCC can lead to more targeted therapies and improved patient outcomes. However, the generation, analysis, and continued utilization of additional genetic and genomic tools are warranted. Tobacco-induced OSCC can be modeled in mice via 4-nitroquinoline 1-oxide (4NQO), which generates a spectrum of neoplastic lesions mimicking human OSCC and upregulates the oncogenic master transcription factor p63. Here, we molecularly characterized established mouse 4NQO treatment-derived OSCC cell lines and utilized RNA and chromatin immunoprecipitation-sequencing to uncover the global p63 gene regulatory and signaling network. We integrated our p63 datasets with published bulk and single-cell RNA-sequencing of mouse 4NQO-treated tongue and esophageal tumors, respectively, to generate a p63-driven gene signature that sheds new light on the role of p63 in murine OSCC. Our analyses reveal known and novel players, such as COTL1, that are regulated by p63 and influence various oncogenic processes, including metastasis. The identification of new sets of potential biomarkers and pathways, some of which are functionally conserved in human OSCC and can prognosticate patient survival, offers new avenues for future mechanistic studies.

Expression of vimentin alters cell mechanics, cell-cell adhesion, and gene expression profiles suggesting the induction of a hybrid EMT in human mammary epithelial cells

Vimentin is a Type III intermediate filament (VIF) cytoskeletal protein that regulates the mechanical and migratory behavior of cells. Its expression is considered to be a marker for the epithelial to mesenchymal transition (EMT) that takes place in tumor metastasis. However, the molecular mechanisms regulated by the expression of vimentin in the EMT remain largely unexplored. We created MCF7 epithelial cell lines expressing vimentin from a cumate-inducible promoter to address this question. When vimentin expression was induced in these cells, extensive cytoplasmic VIF networks were assembled accompanied by changes in the organization of the endogenous keratin intermediate filament networks and disruption of desmosomes. Significant reductions in intercellular forces by the cells expressing VIFs were measured by quantitative monolayer traction force and stress microscopy. In contrast, laser trapping micro-rheology revealed that the cytoplasm of MCF7 cells expressing VIFs was stiffer than the uninduced cells. Vimentin expression activated transcription of genes involved in pathways responsible for cell migration and locomotion. Importantly, the EMT related transcription factor TWIST1 was upregulated only in wild type vimentin expressing cells and not in cells expressing a mutant non-polymerized form of vimentin, which only formed unit length filaments (ULF). Taken together, our results suggest that vimentin expression induces a hybrid EMT correlated with the upregulation of genes involved in cell migration.

The Emerging Role of RNA N6-Methyladenosine Modification in Pancreatic Cancer

Pancreatic cancer (PC) is one of the most common malignant cancers, ranking the seventh highest causes of cancer-related deaths globally. Recently, RNA N6-methyladenosine (m6A) is emerging as one of the most abundant RNA modifications in eukaryote cells, involved in multiple RNA processes including RNA translocation, alternative splicing, maturation, stability, and degradation. As reported, m6A was dynamically and reversibly regulated by its “writers”, “erasers”, and “readers”, Increasing evidence has revealed the vital role of m6A modification in the development of multiple types of cancers including PC. Currently, aberrant m6A modification level has been found in both PC tissues and cell lines. Moreover, abnormal expressions of m6A regulators and m6A-modified genes have been reported to contribute to the malignant development of PC. Here in this review, we will focus on the function and molecular mechanism of m6A-modulated RNAs including coding RNAs as well as non-coding RNAs. Then the m6A regulators will be summarized to reveal their potential applications in the clinical diagnosis, prognosis, and therapeutics of PC.

Desmoglein-3 overexpression in oral squamous cell carcinoma is associated with metastasis formation and early recurrence: An immunohistochemical study

The purpose of this study was to determine the expression patterns of specific desmosomal cadherins (desmogleins [DSG] 1/2/3) in oral squamous cell carcinoma (OSCC), and to examine possible associations with clinicopathological parameters and recurrence rates. Changes in desmosomal cadherin assembly may promote tumor metastasis formation. Patients with surgically treated OSCC with 36-60 months of follow-up (median 46 months) qualified for inclusion in this retrospective cohort study. Demographic, clinical and pathohistological data were collected. DSG-1/2/3 expression patterns were determined by an immunohistochemical approach on tissue microarrays. Descriptive and inferential statistics and survival analyses were computed (p ≤ 0.05). The study sample consisted of 88 patients (female: 38; male: 50; average age: 63.02 ± 17.5 years). DSG-3 overexpression was detected in 45 of 88 specimens. The expression rates for DSG-1 (28/88) and DSG-2 (14/88) were low and inconspicuous. DSG-3 overexpression was significantly associated with poor histologic differentiation (G3, p = 0.001), the presence of cervical node metastasis at primary diagnosis (N+ status, p = 0.001) and early recurrence (p = 0.001). Due to its possible relevance for lymph node metastasis formation and early OSCC recurrence, determination of DSG-3 expression in OSCC specimens may be a valuable tool for treatment planning and post-therapeutic risk assessment.

The long non-coding RNA ET-20 mediates EMT by impairing desmosomes in breast cancer cells

The vast majority of breast cancer-associated deaths are due to metastatic spread of cancer cells, a process aided by epithelial-to-mesenchymal transition (EMT). Mounting evidence has indicated that long non-coding RNAs (lncRNAs) also contribute to tumor progression. We report the identification of 114 novel lncRNAs that change their expression during TGFβ-induced EMT in murine breast cancer cells (referred to as EMT-associated transcripts; ETs). Of these, the ET-20 gene localizes in antisense orientation within the tenascin C (Tnc) gene locus. TNC is an extracellular matrix protein that is critical for EMT and metastasis formation. Both ET-20 and Tnc are regulated by the EMT master transcription factor Sox4. Notably, ablation of ET-20 lncRNA effectively blocks Tnc expression and with it EMT. Mechanistically, ET-20 interacts with desmosomal proteins, thereby impairing epithelial desmosomes and promoting EMT. A short transcript variant of ET-20 is shown to be upregulated in invasive human breast cancer cell lines, where it also promotes EMT. Targeting ET-20 appears to be a therapeutically attractive lead to restrain EMT and breast cancer metastasis in addition to its potential utility as a biomarker for invasive breast cancer.

Paradoxical Roles of Desmosomal Components in Head and Neck Cancer

Desmosomes are intercellular adhesion complexes involved in various aspects of epithelial pathophysiology, including tissue homeostasis, morphogenesis, and disease development. Recent studies have reported that the abnormal expression of various desmosomal components correlates with tumor progression and poor survival. In addition, desmosomes have been shown to act as a signaling platform to regulate the proliferation, invasion, migration, morphogenesis, and apoptosis of cancer cells. The occurrence and progression of head and neck cancer (HNC) is accompanied by abnormal expression of desmosomal components and loss of desmosome structure. However, the role of desmosomal components in the progression of HNC remains controversial. This review aims to provide an overview of recent developments showing the paradoxical roles of desmosomal components in tumor suppression and promotion. It offers valuable insights for HNC diagnosis and therapeutics development.

Novel function of PERP-428 variants impacts lung cancer risk through the differential regulation of PTEN/MDM2/p53-mediated antioxidant activity

Lung cancer is the leading cause of cancer-related deaths worldwide. Identifying genetic risk factors and understanding their mechanisms will help reduce lung cancer incidence. The p53 apoptosis effect is related to PMP-22 (PERP), a tetraspan membrane protein, and an apoptotic effector protein downstream of p53. Although historically considered a tumor suppressor, PERP is highly expressed in lung cancers. Stable knockdown of PERP expression induces CL1-5 and A549 lung cancer cell death, but transient knockdown has no effect. Interestingly, relative to the PERP-428GG genotype, PERP-428CC was associated with the highest lung cancer risk (OR = 5.38; 95% CI = 2.12-13.65, p < 0.001), followed by the PERP-428CG genotype (OR = 2.34; 95% CI = 1.55-3.55, p < 0.001). Ectopic expression of PERP-428G, but not PERP-428C, protects lung cancer cells against ROS-induced DNA damage. Mechanistically, PERP-428 SNPs differentially regulate p53 protein stability. p53 negatively regulates the expression of the antioxidant enzymes catalase (CAT) and glutathione reductase (GR), thereby modulating redox status. p53 protein stability is higher in PERP-428C-expressing cells than in PERP-428G-expressing cells because MDM2 expression is decreased and p53 Ser20 phosphorylation is enhanced in PERP-428C-expressing cells. The MDM2 mRNA level is decreased in PERP-428C-expressing cells via PTEN-mediated downregulation of the MDM2 constitutive p1 promoter. This study reveals that in individuals with PERP-428CC, CAT/GR expression is decreased via the PTEN/MDM2/p53 pathway. These individuals have an increased lung cancer risk. Preventive antioxidants and avoidance of ROS stressors are recommended to prevent lung cancer or other ROS-related chronic diseases.

Tumor levels of the mediators of ErbB2-driven anoikis resistance correlate with breast cancer relapse in patients receiving trastuzumab-based therapies

PURPOSE

Patients with ErbB2/Her2 oncoprotein-positive breast cancers often receive neoadjuvant therapies (NATs) containing the anti-ErbB2 antibody trastuzumab. Tumors that are still present after NATs are resected, and patients continue receiving trastuzumab. These cancers are associated with high relapse risk. Whether relapse will occur cannot be presently reliably predicted. The ability to make such predictions could improve disease management. We found previously that ErbB2 blocks breast tumor cell anoikis, apoptosis induced by cell detachment from the extracellular matrix, by downregulating the pro-apoptotic protein Irf6 and upregulating the anti-apoptotic protein Epidermal Growth Factor Receptor (EGFR) in the cells and, thus, promotes their three-dimensional growth. We now tested whether tumor levels of these proteins before and after NATs correlate with patients' relapse-free survival (RFS) and overall survival (OS).

METHODS

We selected archival breast tumor samples collected from 37 women with ErbB2-positive stages II and III breast cancer before and after NATs. We used immunohistochemistry to test whether levels of the indicated proteins in respective tumors correlate with RFS and OS.

RESULTS

We observed that the presence of high Irf6 levels in the tumors following NATs correlated with reduced RFS and OS. Perhaps not by coincidence, we noticed that trastuzumab-sensitive ErbB2-positive breast cancer cells selected for the ability to overproduce exogenous Irf6 in culture acquired trastuzumab resistance. Finally, EGFR presence in patients' tumors before or after NATs was associated with decreased RFS and OS.

CONCLUSIONS

This study could help identify patients with ErbB2-positive tumors that are at increased risk of disease relapse following NATs.

Multi-Omics Analysis of Anlotinib in Pancreatic Cancer and Development of an Anlotinib-Related Prognostic Signature

Aberrant regulation of angiogenesis involves in the growth and metastasis of tumors, but angiogenesis inhibitors fail to improve overall survival of pancreatic cancer patients in previous phase III clinical trials. A comprehensive knowledge of the mechanism of angiogenesis inhibitors against pancreatic cancer is helpful for clinical purpose and for the selection of patients who might benefit from the inhibitors. In this work, multi-omics analyses (transcriptomics, proteomics, and phosphoproteomics profiling) were carried out to delineate the mechanism of anlotinib, a novel angiogenesis inhibitor, against pancreatic cancer cells. The results showed that anlotinib exerted noteworthy cytotoxicity on pancreatic cancer cells. Multi-omics analyses revealed that anlotinib had a profound inhibitory effect on ribosome, and regulated cell cycle, RNA metabolism and lysosome. Based on the multi-omics results and available data deposited in public databases, an anlotinib-related gene signature was further constructed to identify a subgroup of pancreatic cancer patients who had a dismal prognosis and might be responsive to anlotinib.

Transcriptional and signalling regulation of skin epithelial stem cells in homeostasis, wounds and cancer

The epidermis and skin appendages are maintained by their resident epithelial stem cells, which undergo long-term self-renewal and multilineage differentiation. Upon injury, stem cells are activated to mediate re-epithelialization and restore tissue function. During this process, they often mount lineage plasticity and expand their fates in response to damage signals. Stem cell function is tightly controlled by transcription machineries and signalling transductions, many of which derail in degenerative, inflammatory and malignant dermatologic diseases. Here, by describing both well-characterized and newly emerged pathways, we discuss the transcriptional and signalling mechanisms governing skin epithelial homeostasis, wound repair and squamous cancer. Throughout, we highlight common themes underscoring epithelial stem cell plasticity and tissue-level crosstalk in the context of skin physiology and pathology.

Insulin receptor substrate 1 gene expression is strongly up-regulated by HSPB8 silencing in U87 glioma cells

Objective. The aim of the present investigation was to study the expression of genes encoding IRS1 (insulin receptor substrate 1) and some other functionally active proteins in U87 glioma cells under silencing of polyfunctional chaperone HSPB8 for evaluation of the possible significance of this protein in intergenic interactions.Methods. Silencing of HSPB8 mRNA was introduced by HSPB8 specific siRNA. The expression level of HSPB8, IRS1, HK2, GLO1, HOMER3, MYL9, NAMPT, PER2, PERP, GADD45A, and DEK genes was studied in U87 glioma cells by quantitative polymerase chain reaction.Results. It was shown that silencing of HSPB8 mRNA by specific to HSPB8 siRNA led to a strong down-regulation of this mRNA and significant modification of the expression of IRS1 and many other genes in glioma cells: strong up-regulated of HOMER3, GLO1, and PERP and down-regulated of MYL9, NAMPT, PER2, GADD45A, and DEK gene expressions. At the same time, no significant changes were detected in the expression of HK2 gene in glioma cells treated by siRNA, specific to HSPB8. Moreover, the silencing of HSPB8 mRNA enhanced the glioma cells proliferation rate.Conclusions. Results of this investigation demonstrated that silencing of HSPB8 mRNA affected the expression of IRS1 gene as well as many other genes encoding tumor growth related proteins. It is possible that the dysregulation of most of the studied genes in glioma cells after silencing of HSPB8 is reflected by a complex of intergenic interactions and that this polyfunctional chaperone is an important factor for the stability of genome function and regulatory mechanisms contributing to the tumorigenesis control.

TP63 links chromatin remodeling and enhancer reprogramming to epidermal differentiation and squamous cell carcinoma development

Squamous cell carcinoma (SCC) is an aggressive malignancy that can originate from various organs. TP63 is a master regulator that plays an essential role in epidermal differentiation. It is also a lineage-dependent oncogene in SCC. ΔNp63α is the prominent isoform of TP63 expressed in epidermal cells and SCC, and overexpression promotes SCC development through a variety of mechanisms. Recently, ΔNp63α was highlighted to act as an epidermal-specific pioneer factor that binds closed chromatin and enhances chromatin accessibility at epidermal enhancers. ΔNp63α coordinates chromatin-remodeling enzymes to orchestrate the tissue-specific enhancer landscape and three-dimensional high-order architecture of chromatin. Moreover, ΔNp63α establishes squamous-like enhancer landscapes to drive oncogenic target expression during SCC development. Importantly, ΔNp63α acts as an upstream regulator of super enhancers to activate a number of oncogenic transcripts linked to poor prognosis in SCC. Mechanistically, ΔNp63α activates genes transcription through physically interacting with a number of epigenetic modulators to establish enhancers and enhance chromatin accessibility. In contrast, ΔNp63α also represses gene transcription via interacting with repressive epigenetic regulators. ΔNp63α expression is regulated at multiple levels, including transcriptional, post-transcriptional, and post-translational levels. In this review, we summarize recent advances of p63 in epigenomic and transcriptional control, as well as the mechanistic regulation of p63.

Upregulation of METTL14 mediates the elevation of PERP mRNA N6 adenosine methylation promoting the growth and metastasis of pancreatic cancer

Background

Pancreatic cancer is one of the most lethal human cancers. N⁶-methyladenosine (m⁶A), a common eukaryotic mRNA modification, plays critical roles in both physiological and pathological processes. However, its role in pancreatic cancer remains elusive.

Methods

LC/MS was used to profile m⁶A levels in pancreatic cancer and normal tissues. Bioinformatics analysis, real-time PCR, immunohistochemistry, and western blotting were used to identify the role of m⁶A regulators in pancreatic cancer. The biological effects of methyltransferase-like 14 (METTL14), an mRNA methylase, were investigated using in vitro and in vivo models. MeRIP-Seq and RNA-Seq were used to assess the downstream targets of METTL14.

Results

We found that the m⁶A levels were elevated in approximately 70% of the pancreatic cancer samples. Furthermore, we demonstrated that METTL14 is the major enzyme that modulates m⁶A methylation (frequency and site of methylation). METTL14 overexpression markedly promoted pancreatic cancer cell proliferation and migration both in vitro and in vivo, via direct targeting of the downstream PERP mRNA (p53 effector related to PMP-22) in an m⁶A-dependent manner. Methylation of the target adenosine lead to increased PERP mRNA turnover, thus decreasing PERP (mRNA and protein) levels in pancreatic cancer cells.

Conclusions

Our data suggest that the upregulation of METTL14 leads to the decrease of PERP levels via m⁶A modification, promoting the growth and metastasis of pancreatic cancer; therefore METTL14 is a potential therapeutic target for its treatment.

PERP-ing into diverse mechanisms of cancer pathogenesis: Regulation and role of the p53/p63 effector PERP

The tetraspan plasma membrane protein PERP (p53 apoptosis effector related to PMP22) is a lesser-known transcriptional target of p53 and p63. A member of the PMP22/GAS3/EMP membrane protein family, PERP was originally identified as a p53 target specifically trans-activated during apoptosis, but not during cell-cycle arrest. Several studies have since shown downregulation of PERP expression in numerous cancers, suggesting that PERP is a tumour suppressor protein. This review focusses on the important advances made in elucidating the mechanisms regulating PERP expression and its function as a tumour suppressor in diverse human cancers, including breast cancer and squamous cell carcinoma. Investigating PERP's role in clinically-aggressive uveal melanoma has revealed that PERP engages a positive-feedback loop with p53 to regulate its own expression, and that p63 is required beside p53 to achieve pro-apoptotic levels of PERP in this cancer. Furthermore, the recent discovery of the apoptosis-mediating interaction of PERP with SERCA2b at the plasma membrane-endoplasmic reticulum interface demonstrates a novel mechanism of PERP stabilisation, and how PERP can mediate Ca²⁺ signalling to facilitate apoptosis. The multi-faceted role of PERP in cancer, involving well-documented functions in mediating apoptosis and cell-cell adhesion is discussed, alongside PERP's emerging roles in epithelial-mesenchymal transition, and PERP crosstalk with inflammation signalling pathways, and other signalling pathways. The potential for restoring PERP expression as a means of cancer therapy is also considered.

Pilot study of loss of the p53/p63 target gene PERP at the surgical margin as a potential predictor of local relapse in head and neck squamous cell carcinoma

BACKGROUND

PERP (p53 apoptosis effector related to PMP22) localizes to desmosomes and suppresses squamous cell carcinoma development. Loss of PERP leads to worse local control in head and neck squamous cell carcinoma (HNSCC), likely by destabilizing desmosomes. We evaluated PERP loss at HNSCC surgical margins as a predictor of local relapse.

METHODS

Combining discovery (n = 17) and validation (n = 31) cohorts, we examined membranous PERP protein expression by immunohistochemistry in surgical mucosal margins with competing risk analysis of the relationship between local relapse and PERP expression.

RESULTS

Of the 44 analyzable patients, the 2-year cumulative incidence of local relapse was 44.4% for the PERP-negative group and 16.4% for the PERP-positive group (P = .01). A trend toward worse progression-free survival (P = .09) and overall survival (P = .06) was observed with loss of PERP.

CONCLUSIONS

PERP loss at surgical margins is associated with higher risk of local recurrence in HNSCC, warranting further evaluation in a larger prospective study.

Genetic Factors Involved in Cardiomyopathies and in Cancer

Cancer therapy-induced cardiomyopathy (CCM) manifests as left ventricular (LV) dysfunction and heart failure (HF). It is associated withparticular pharmacological agents and it is typically dose dependent, but significant individual variability has been observed. History of prior cardiac disease, abuse of toxics, cardiac overload conditions, age, and genetic predisposing factors modulate the degree of the cardiac reserve and the response to the injury. Genetic/familial cardiomyopathies (CMY) are increasingly recognized in general populations with an estimated prevalence of 1:250. Association between cardiac and oncologic diseases regarding genetics involves not only the toxicity process, but pathogenicity. Genetic variants in germinal cells that cause CMY (LMNA, RAS/MAPK) can increase susceptibility for certain types of cancer. The study of mutations found in cancer cells (somatic) has revealed the implication of genes commonly associated with the development of CMY. In particular, desmosomal mutations have been related to increased undifferentiation and invasiveness of cancer. In this article, the authors review the knowledge on the relevance of environmental and genetic background in CCM and give insights into the shared genetic role in the pathogenicity of the cancer process and development of CMY.

Analysis of gene expression profiles of lung cancer subtypes with machine learning algorithms

Lung cancer is one of the most common cancer types worldwide and causes more than one million deaths annually. Lung adenocarcinoma (AC) and lung squamous cell cancer (SCC) are two major lung cancer subtypes and have different characteristics in several aspects. Identifying their differentially expressed genes and different gene expression patterns can deepen our understanding of these two subtypes at the transcriptomic level. In this work, we used several machine learning algorithms to investigate the gene expression profiles of lung AC and lung SCC samples retrieved from Gene Expression Omnibus. First, the profiles were analyzed by using a powerful feature selection method, namely, Monte Carlo feature selection. A feature list, ranking all features according to their importance, and some informative features were obtained. Then, the feature list was used in the incremental feature selection method to extract optimal features, which can allow the support vector machine (SVM) to yield the best performance for classifying lung AC and lung SCC samples. Some top genes (CSTA, TP63, SERPINB13, CLCA2, BICD2, PERP, FAT2, BNC1, ATP11B, FAM83B, KRT5, PARD6G, PKP1) were extensively analyzed to prove that they can be differentially expressed genes between lung AC and lung SCC. Meanwhile, a rule learning procedure was applied on informative features to construct the classification rules. These rules provide a clear procedure of classification and show some different gene expression patterns between lung AC and lung SCC.

Promoter Hypomethylation and Increased Expression of the Long Non-coding RNA LINC00152 Support Colorectal Carcinogenesis

Up-regulation of the long non-coding RNA LINC00152 can contribute to cancer development, proliferation and invasion, including colorectal cancer, however, its mechanism of action in colorectal carcinogenesis and progression is only insufficiently understood. In this work we correlated LINC00152 expression with promoter DNA methylation changes in colorectal tissues along the normal-adenoma-carcinoma sequence and studied the effects of LINC00152 silencing on the cell cycle regulation and on the whole transcriptome in colon carcinoma cells using cell and molecular biology techniques. LINC00152 was significantly up-regulated in adenoma and colorectal cancer (p < 0.001) compared to normal samples, which was confirmed by real-time PCR and in situ hybridization. LINC00152 promoter hypomethylation detected in colorectal cancer (p < 0.01) was strongly correlated with increased LINC00152 expression (r=-0.90). Silencing of LINC00152 significantly suppressed cell growth, induced apoptosis and decreased cyclin D1 expression (p < 0.05). Whole transcriptome analysis of LINC00152-silenced cells revealed significant down-regulation of oncogenic and metastasis promoting genes (e.g. YES proto-oncogene 1, PORCN porcupine O-acyltransferase), and up-regulation of tumour suppressor genes (e.g. DKK1 dickkopf WNT signalling pathway inhibitor 1, PERP p53 apoptosis effector) (adjusted p < 0.05). Pathway analysis confirmed the LINC00152-related activation of oncogenic molecular pathways including those driven by PI3K/Akt, Ras, WNT, TP53, Notch and ErbB. Our results suggest that promoter hypomethylation related overexpression of LINC00152 can contribute to the pathogenesis of colorectal cancer by facilitating cell progression through the up-regulation of several oncogenic and metastasis promoting pathway elements.

PTPN13 induces cell junction stabilization and inhibits mammary tumor invasiveness

Clinical data suggest that the protein tyrosine phosphatase PTPN13 exerts an anti-oncogenic effect. Its exact role in tumorigenesis remains, however, unclear due to its negative impact on FAS receptor-induced apoptosis.

Methods: We crossed transgenic mice deleted for PTPN13 phosphatase activity with mice that overexpress human HER2 to assess the exact role of PTPN13 in tumor development and aggressiveness. To determine the molecular mechanism underlying the PTPN13 tumor suppressor activity we developed isogenic clones of the aggressive human breast cancer cell line MDA-MB-231 overexpressing either wild type or a catalytically-inactive mutant PTPN13 and subjected these to phosphoproteomic and gene ontology analyses.

We investigated the PTPN13 consequences on cell aggressiveness using wound healing and Boyden chamber assays, on intercellular adhesion using videomicroscopy, cell aggregation assay and immunofluorescence.

Results: The development, growth and invasiveness of breast tumors were strongly increased by deletion of the PTPN13 phosphatase activity in transgenic mice. We observed that PTPN13 phosphatase activity is required to inhibit cell motility and invasion in the MDA-MB-231 cell line overexpressing PTPN13. In vivo, the negative PTPN13 effect on tumor invasiveness was associated with a mesenchymal-to-epithelial transition phenotype in athymic mice xenografted with PTPN13-overexpressing MDA-MB-231 cells, as well as in HER2-overexpressing mice with wild type PTPN13, compared to HER2-overexpressing mice that lack PTPN13 phosphatase activity. Phosphoproteomic and gene ontology analyses indicated a role of PTPN13 in the regulation of intercellular junction-related proteins. Finally, protein localization studies in MDA-MB-231 cells and HER2-overexpressing mice tumors confirmed that PTPN13 stabilizes intercellular adhesion and promotes desmosome formation.

Conclusions: These data provide the first evidence for the negative role of PTPN13 in breast tumor invasiveness and highlight its involvement in cell junction stabilization.

SKA3 Promotes tumor growth by regulating CDK2/P53 phosphorylation in hepatocellular carcinoma

Spindle and kinetochore-related complex subunit 3 (SKA3) is a component of the spindle and kinetochore-related complexes and is essential for accurate timing of late mitosis. However, the relationship between SKA3 and hepatocellular carcinoma (HCC) has not yet been fully elucidated. Gene expression omnibus (GEO) (GSE62232, GSE45436, GSE6764, and GSE36376) and The Cancer Atlas (TCGA) datasets were analyzed to identify differential expression genes. Cell proliferation ability was analyzed using Cell Counting Kit-8 (CCK8) assay and plate clone formation assay, while scratch wound healing assay and transwell assay were used to analyze cell invasion. The role of SKA3 in vivo was explored using subcutaneous xenotransplantation model and lung metastasis model. Bioinformatics analysis found that hepatocellular carcinoma patients with high levels of expression of SKA3 have a poor prognosis. Similarly, immunohistochemical staining of 236 samples of tumors also found higher SKA3 expression in them, than in adjacent normal liver tissues. Significant levels of inhibition of in vivo and in vitro tumor proliferation and invasion result from the downregulation of SKA3. Mechanistically, SKA3 was found to affect tumor progression through the cell cycle and P53 signaling pathway as shown by the gene enrichment analysis (GSEA). G2/M phase arrest and severe apoptosis was also found to result from SKA3 knockdown, as shown by the inhibition of CDK2/p53 phosphorylation together with downregulation of BAX/Bcl-2 expression in HCC cells. Overall, these findings uncover the role of SKA3 in regulating the apoptosis and proliferation of hepatocellular carcinoma cells. This study was able to uncover new information on the tumorigenesis mechanism in hepatocellular carcinoma.

Identification of gene co-expression modules and hub genes associated with lymph node metastasis of papillary thyroid cancer

Papillary thyroid cancer (PTC) is the most prevalent histological type among thyroid cancers, and some patients are at a high risk for recurrent disease or even death. Identification for the potential biomarkers of PTC may contribute to early discovery of recurrence and treatment. In The Cancer Genome Atlas (TCGA) database, we obtained the information of RNA sequence data and clinical characteristics of PTC. Weighted gene co-expression network analysis (WGCNA) was performed to construct gene co-expression networks and investigate the relationship between modules and clinical traits. Finally, we constructed 16 co-expression modules in 10,428 genes, and three key modules (darkturquoise, lightyellow, and red) associated with tumor N grade were identified. The results of functional annotation indicated that the darkturquoise module was primarily enriched in the regulation of the extracellular matrix (ECM), collagen metabolism, and cell adhesion, the lightyellow module was primarily enriched in the mitochondrial function regulation and energy synthesis, and the red module was primarily enriched in the process of cell junction, apoptosis, and inflammatory response, suggesting their significant role in the progression of PTC. In addition, the hub genes in the three modules were identified and screened for differentially expressed genes (DEGs). Relapse-free survival analyses found that 11 genes (KCNQ3, MET, FN1, ITGA3, RUNX1, ITGA2, PERP, GCSH, FAAH, NGFRAP1, and HSPA5) may play a pivotal role in PTC relapse. In general, our research revealed the key co-expression modules and identified several prognostic biomarkers, which provides some new insights into the lymph node metastasis of PTC.

LncRNA MIR4435-2HG targets desmoplakin and promotes growth and metastasis of gastric cancer by activating Wnt/β-catenin signaling

Long non-coding RNAs (lncRNAs) have been implicated in the pathogenesis of gastric cancer; however, their mechanisms of action remain largely unknown. The aim of this study was to identify lncRNAs involved in the tumorigenesis of gastric cancer and to investigate the signaling pathways they affect. Using microarray and RT-qPCR analyses, candidate lncRNAs were screened in paired gastric cancer tissues. The analysis revealed MIR4435-2HG to be markedly up-regulated in gastric cancer samples compared to normal stomach specimens. Increased MIR4435-2HG expression was associated with aggressive clinicopathologic features and unfavorable tumor stage. Functional experiments showed that MIR4435-2HG up-regulation enhanced gastric cancer cell proliferation, clonogenicity, and migration and invasion in vitro, as well as tumorigenicity in mice. Using RNA pull-down and mass-spectrometry analyses we found and verified a direct and novel interaction between MIR4435-2HG and desmoplakin (DSP), the most abundant desmosomal protein. Overexpression and knockdown experiments revealed opposing roles for DSP and MIR4435-2HG, unmasking a cascade through which MIR4435-2HG binds to and inhibits DSP, leading to activation of WNT/β-catenin signaling and epithelial-mesenchymal transition in gastric cancer cells. We propose that the MIR4435-2HG/DSP/WNT axis serves as a critical effector of carcinogenesis and progression of gastric cancer, and could be exploited therapeutically to improve patients' outcomes.

Glucolipotoxicity-Inhibited miR-299-5p Regulates Pancreatic β-Cell Function and Survival

Inhibition of microRNAs (miRNAs) essential for pancreatic β-cell biology (e.g., miR-375) results in β-cell failure and diabetes in rodent models. Whether the downregulation of miRNAs in pancreatic islets is involved in the development of human type 2 diabetes remains unclear. Here, with the use of an miRNA microarray, we identified a set of miRNAs that were differentially expressed in healthy human islets under glucolipotoxic conditions. A downregulated miRNA, miR-299-5p, was preferentially studied because its inhibition causes dramatic β-cell dysfunction and apoptosis. Proteomic profiling and bioinformatics methods identified four target genes, including a Trp53 effector, Perp, that were further confirmed by luciferase reporter assays. We narrowed down the effector of miR-299-5p downregulation to PERP owing to its upregulation in islets from diabetic rodents. Indeed, Perp inhibition prevented the β-cell impairment caused by either miR-299-5p reduction or glucolipotoxicity. Additional investigations confirmed the modulatory effect of PERP on insulin secretion. Collectively, miR-299-5p appears to be an essential regulator of β-cell biology, and its downregulation links PERP enhancement to β-cell dysfunction and apoptosis in glucolipotoxic settings. Our work demonstrates a novel mechanism of glucolipotoxicity-induced β-cell failure mediated through miR-299-5p downregulation.

ZNF185 is a p63 target gene critical for epidermal differentiation and squamous cell carcinoma development

Development and maintenance of healthy stratified epithelia require the coordination of complex transcriptional programmes. The transcription factor p63, a member of the p53 family, plays a crucial role in epithelial development and homeostasis. Analysis of the p63-dependent transcriptome indicated that one important aspect of p63 functions in epithelial development is the regulation of cell–cell and cell–matrix adhesion programmes. However, limited knowledge exists on the relevant cell–cell adhesion molecules involved in physiological epithelial formation. Similarly, limited data are available to understand if deregulation of the cell–cell adhesion programme is important in tumour formation. Here, using the epidermis as an experimental model with the RNA sequencing approach, we identify a novel p63-regulated gene induced during differentiation, ZNF185. ZNF185 is an actin-cytoskeleton-associated Lin-l 1, Isl-1 and Mec-3 (LIM) domain-containing protein, whose function is poorly known. We found that p63 binds to a specific enhancer region, promoting its expression to sustain epithelial differentiation. ZNF185 silencing strongly impaired keratinocyte differentiation according to gene array analysis. ZNF185 is detected at the cell–cell periphery where it physically interacts with E-cadherin, indicating that it is important to maintain epithelial integrity beyond its pro-differentiation role. Interestingly, poorly differentiated, including head and neck, cervical and oesophageal, squamous cell carcinomas display loss of ZNF185 expression. Together, these studies reinforce that p63 is a crucial gene for maintaining epithelial tissue integrity and support the deregulation of the cell-cell adhesion programme,which plays a critical role in carcinoma development.

Mutations in PERP Cause Dominant and Recessive Keratoderma

Investigation of genetic determinants of Mendelian skin disorders has substantially advanced understanding of epidermal biology. Here we show that mutations in PERP, encoding a crucial component of desmosomes, cause both dominant and recessive human keratoderma. Heterozygosity for a C-terminal truncation, which produces a protein that appears to be unstably incorporated into desmosomes, causes Olmsted syndrome with severe periorificial and palmoplantar keratoderma in multiple unrelated kindreds. Homozygosity for an N-terminal truncation ablates expression and causes widespread erythrokeratoderma, with expansion of epidermal differentiation markers. Both exhibit epidermal hyperproliferation, immature desmosomes lacking a dense midline observed via electron microscopy, and impaired intercellular adhesion upon mechanical stress. Localization of other desmosomal components appears normal, which is in contrast to other conditions caused by mutations in genes encoding desmosomal proteins. These discoveries highlight the essential role of PERP in human desmosomes and epidermal homeostasis and further expand the heterogeneous spectrum of inherited keratinization disorders.

Tricho-rhino-phalangeal syndrome 1 protein functions as a scaffold required for ubiquitin-specific protease 4-directed histone deacetylase 2 de-ubiquitination and tumor growth

Background

Although numerous studies have reported that tricho-rhino-phalangeal syndrome type I (TRPS1) protein, the only reported atypical GATA transcription factor, is overexpressed in various carcinomas, the underlying mechanism(s) by which it contributes to cancer remain unknown.

Methods

Both overexpression and knockdown of TRPS1 assays were performed to examine the effect of TRPS1 on histone deacetylase 2 (HDAC2) protein level and luminal breast cancer cell proliferation. Also, RT-qRCR, luciferase reporter assay and RNA-sequencing were used for transcription detection. Chromatin immunoprecipitation (ChIP) using H4K16ac antibody in conjunction with qPCR was used for determining H4K16ac levels in targeted genes. Furthermore, in vitro cell proliferation assay and in vivo tumor xenografts were used to detect the effect of TRPS1 on tumor growth.

Results

We found that TRPS1 scaffolding recruits and enhances interaction between USP4 and HDAC2 leading to HDAC2 de-ubiquitination and H4K16 deacetylation. We detected repression of a set of cellular growth-related genes by the TRPS1-USP4-HDAC2 axis indicating it is essential in tumor growth. In vitro and in vivo experiments confirmed that silencing TRPS1 reduced tumor growth, whereas overexpression of HDAC2 restored tumor growth.

Conclusion

Our study deciphered the TRPS1-USP4-HDAC2 axis as a novel mechanism that contributes to tumor growth. Significantly, our results revealed the scaffolding function of TPRS1 in USP4-directed HDAC2 de-ubiquitination and provided new mechanistic insights into the crosstalk between TRPS1, ubiquitin, and histone modification systems leading to tumor growth.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-1018-7) contains supplementary material, which is available to authorized users.

Deconstructing networks of p53-mediated tumor suppression in vivo

The transcription factor p53 is a vital tumor suppressor. Upon activation by diverse stresses including oncogene activation, DNA damage, hypoxia and nutrient deprivation, p53 activates a panoply of target genes and orchestrates numerous downstream responses that suppress tumorigenesis. Although early studies of p53 suggested that its ability to induce cell cycle arrest, senescence and apoptosis programs accounted for its tumor-suppressor activity, more recent studies have challenged this notion. Moreover, p53 regulates a suite of additional processes, such as metabolism, stem cell function, invasion and metastasis. The processes p53 coordinately regulates to enact tumor suppression, and how such regulation occurs, thus remain elusive. In this review, we will summarize our current knowledge of p53-mediated tumor-suppressive mechanisms gleaned from in vivo studies in mouse models.

Elucidating the Role of the Desmosome Protein p53 Apoptosis Effector Related to PMP-22 in Growth Hormone Tumors

Densely granulated and sparsely granulated (SG) growth hormone (GH) pituitary adenomas differ in biological behavior, which may be correlated with their known differences in cytoplasmic keratin distribution and E-cadherin expression. We wanted to explore candidate genes that might further explain this behavior. Exon expression microarray was performed on 21 GH tumors (10 SG and 11 densely granulated) and 20 normal control pituitaries from autopsy. Bioinformatic analyses confirmed a differential molecular signature between normal pituitary and GH tumors as well as between the GH tumor subtypes. There was a consistent downregulation of transcripts involved in the structure and function of the desmosome, including desmoplakin (eightfold), desmoglein 2 (sixfold), plakophilin 2 (sevenfold), and p53 apoptosis effector related to PMP-22 (PERP; sixfold) in SG tumors compared with normal pituitary. PERP is lost in more aggressive SG human GH pituitary tumors. PERP re-expression in GH3 rat GH tumor cells resulted in decreased colony formation compared with vector transfectants, confirming the role of PERP as a tumor suppressor with no effects on proliferation. Increased PERP expression was associated with loss of a survival advantage in a hypoxic environment, as assessed by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (P < 0.05) and cleaved caspase-3 (P < 0.05). Downregulation of desmosomal formation transcripts including PERP may contribute to the aggressive phenotype seen in SG GH pituitary tumors and their behavior in response to surgery and medical therapy.

Transcriptomic comparison of primary bovine horn core carcinoma culture and parental tissue at early stage

Aim:

Squamous cell carcinoma or SCC of horn in bovines (bovine horn core carcinoma) frequently observed in Bos indicus affecting almost 1% of cattle population. Freshly isolated primary epithelial cells may be closely related to the malignant epithelial cells of the tumor. Comparison of gene expression in between horn’s SCC tissue and its early passage primary culture using next generation sequencing was the aim of this study.

Materials and Methods:

Whole transcriptome sequencing of horn’s SCC tissue and its early passage cells using Ion Torrent PGM were done. Comparative expression and analysis of different genes and pathways related to cancer and biological processes associated with malignancy, proliferating capacity, differentiation, apoptosis, senescence, adhesion, cohesion, migration, invasion, angiogenesis, and metabolic pathways were identified.

Results:

Up-regulated genes in SCC of horn’s early passage cells were involved in transporter activity, catalytic activity, nucleic acid binding transcription factor activity, biogenesis, cellular processes, biological regulation and localization and the down-regulated genes mainly were involved in focal adhesion, extracellular matrix receptor interaction and spliceosome activity.

Conclusion:

The experiment revealed similar transcriptomic nature of horn’s SCC tissue and its early passage cells.

ErbB2-dependent downregulation of a pro-apoptotic protein Perp is required for oncogenic transformation of breast epithelial cells

The ability of breast cancer cells to resist anoikis, apoptosis caused by detachment of the non-malignant epithelial cells from the extracellular matrix (ECM), is thought to be critical for breast tumor growth, invasion and metastasis. ErbB2, an oncoprotein that is often overproduced in breast tumors, can block breast cancer cell anoikis via mechanisms that are understood only in part. In an effort to understand them better we found that detachment of the non-malignant human breast epithelial cells from the ECM upregulates a protein Perp in these cells. Perp is a component of the desmosomes, multiprotein complexes involved in cell-to-cell adhesion. Perp can cause apoptosis via unknown mechanisms. We demonstrated that Perp upregulation by cell detachment is driven by detachment-induced loss of epidermal growth factor receptor (EGFR). We also found that Perp knockdown by RNA interference (RNAi) rescues detached cells from death which indicates that Perp contributes to their anoikis. We observed that ErbB2, when overexpressed in detached breast epithelial cells, causes Perp downregulation. Furthermore, ErbB2-directed RNAi or treatment with lapatinib, an ErbB2/EGFR small-molecule inhibitor used for breast cancer therapy, upregulated Perp in ErbB2-positive human breast and ovarian carcinoma cells. We established that ErbB2 downregulates Perp by activating an ErbB2 effector protein kinase Mek that blocks detachment-induced EGFR loss in a manner that requires the presence of a signaling protein Sprouty-2. Finally, we observed that restoration of the wild-type Perp levels in ErbB2-overproducing breast epithelial cells increases their anoikis susceptibility and blocks their clonogenicity in the absence of adhesion to the ECM. In summary, we have identified a novel mechanism of ErbB2-mediated mechanism of anoikis resistance of ErbB2-overproducing breast epithelial cells. This mechanism allows such cells to grow without adhesion to the ECM and is driven by ErbB2-induced activation of Mek, subsequent EGFR upregulation and further EGFR-dependent Perp loss.

150th Anniversary Series: Desmosomes and the Hallmarks of Cancer

Desmosomes represent adhesive, spot-like intercellular junctions that in association with intermediate filaments mechanically link neighboring cells and stabilize tissue architecture. In addition to this structural function, desmosomes also act as signaling platforms involved in the regulation of cell proliferation, differentiation, migration, morphogenesis, and apoptosis. Thus, deregulation of desmosomal proteins has to be considered to contribute to tumorigenesis. Proteolytic fragmentation and downregulation of desmosomal cadherins and plaque proteins by transcriptional or epigenetic mechanisms were observed in different cancer entities suggesting a tumor-suppressive role. However, discrepant data in the literature indicate that context-dependent differences based on alternative intracellular, signal transduction lead to altered outcome. Here, modulation of Wnt/β-catenin signaling by plakoglobin or desmoplakin and of epidermal growth factor receptor signaling appears to be of special relevance. This review summarizes current evidence on how desmosomal proteins participate in carcinogenesis, and depicts the molecular mechanisms involved.

MMP7 is required to mediate cell invasion and tumor formation upon Plakophilin3 loss

Plakophilin3 (PKP3) loss results in increased transformation in multiple cell lines in vitro and increased tumor formation in vivo. A microarray analysis performed in the PKP3 knockdown clones, identified an inflammation associated gene signature in cell lines derived from stratified epithelia as opposed to cell lines derived from simple epithelia. However, in contrast to the inflammation associated gene signature, the expression of MMP7 was increased upon PKP3 knockdown in all the cell lines tested. Using vector driven RNA interference, it was demonstrated that MMP7 was required for in-vitro cell migration and invasion and tumor formation in vivo. The increase in MMP7 levels was due to the increase in levels of the Phosphatase of Regenerating Liver3 (PRL3), which is observed upon PKP3 loss. The results suggest that MMP7 over-expression may be one of the mechanisms by which PKP3 loss leads to increased cell invasion and tumor formation.

Desmosomes in acquired disease

Desmosomes are cell-cell junctions that mediate adhesion and couple the intermediate filament cytoskeleton to sites of cell-cell contact. This architectural arrangement integrates adhesion and cytoskeletal elements of adjacent cells. The importance of this robust adhesion system is evident in numerous human diseases, both inherited and acquired, which occur when desmosome function is compromised. This review focuses on autoimmune and infectious diseases that impair desmosome function. In addition, we discuss emerging evidence that desmosomal genes are often misregulated in cancer. The emphasis of our discussion is placed on the way in which human diseases can inform our understanding of basic desmosome biology and in turn, the means by which fundamental advances in the cell biology of desmosomes might lead to new treatments for acquired diseases of the desmosome.

PERP, a host tetraspanning membrane protein, is required for Salmonella-induced inflammation

Salmonella enterica  Typhimurium induces intestinal inflammation through the activity of type III secreted effector (T3SE) proteins. Our prior results indicate that the secretion of the T3SE SipA and the ability of SipA to induce epithelial cell responses that lead to induction of polymorphonuclear transepithelial migration are not coupled to its direct delivery into epithelial cells from Salmonella. We therefore tested the hypothesis that SipA interacts with a membrane protein located at the apical surface of intestinal epithelial cells. Employing a split ubiquitin yeast‐two‐hybrid screen, we identified the tetraspanning membrane protein, p53 effector related to PMP‐22 (PERP), as a SipA binding partner. SipA and PERP appear to have intersecting activities as we found PERP to be involved in proinflammatory pathways shown to be regulated by SipA. In sum, our studies reveal a critical role for PERP in the pathogenesis of S. Typhimurium, and for the first time demonstrate that SipA, a T3SE protein, can engage a host protein at the epithelial surface.

Desmosomes: regulators of cellular signaling and adhesion in epidermal health and disease

Desmosomes are intercellular junctions that mediate cell-cell adhesion and anchor the intermediate filament network to the plasma membrane, providing mechanical resilience to tissues such as the epidermis and heart. In addition to their critical roles in adhesion, desmosomal proteins are emerging as mediators of cell signaling important for proper cell and tissue functions. In this review we highlight what is known about desmosomal proteins regulating adhesion and signaling in healthy skin-in morphogenesis, differentiation and homeostasis, wound healing, and protection against environmental damage. We also discuss how human diseases that target desmosome molecules directly or interfere indirectly with these mechanical and signaling functions to contribute to pathogenesis.

Unravelling mechanisms of p53-mediated tumour suppression

p53 is a crucial tumour suppressor that responds to diverse stress signals by orchestrating specific cellular responses, including transient cell cycle arrest, cellular senescence and apoptosis, which are all processes associated with tumour suppression. However, recent studies have challenged the relative importance of these canonical cellular responses for p53-mediated tumour suppression and have highlighted roles for p53 in modulating other cellular processes, including metabolism, stem cell maintenance, invasion and metastasis, as well as communication within the tumour microenvironment. In this Opinion article, we discuss the roles of classical p53 functions, as well as emerging p53-regulated processes, in tumour suppression.

Loss of Grainy head-like 1 is associated with disruption of the epidermal barrier and squamous cell carcinoma of the skin

The Grainyhead-like 1 (GRHL1) transcription factor regulates the expression of desmosomal cadherin desmoglein 1 (Dsg1) in suprabasal layers of the epidermis. As a consequence, the epidermis of Grhl1-null mice displays fewer desmosomes that are abnormal in structure. These mice also exhibit mild chronic skin barrier defects as evidenced by altered keratinocyte terminal differentiation, increased expression of inflammatory markers and infiltration of the skin by immune cells. Exposure of Grhl1^−/− mice to a standard chemical skin carcinogenesis protocol results in development of fewer papillomas than in wild type control animals, but with a rate of conversion to squamous cell carcinoma (SCC) that is strikingly higher than in normal littermates. The underlying molecular mechanism differs from mice with conditional ablation of a closely related Grhl family member, Grhl3, in the skin, which develop SCC due to the loss of expression of phosphatase and tensin homolog (PTEN) and activation of the phosphatidylinositol 3-kinase (PI3K)/AKT/mechanistic target of rapamycin (mTOR) signaling pathway.

Salivary proteomics in bisphosphonate-related osteonecrosis of the jaw

OBJECTIVE

The objective of this study was to identify differentially expressed salivary proteins in bisphosphonate-related osteonecrosis of the jaw (BRONJ) patients that could serve as biomarkers for BRONJ diagnosis.

SUBJECTS AND METHODS

Whole saliva obtained from 20 BRONJ patients and 20 controls were pooled within groups. The samples were analyzed using iTRAQ-labeled two-dimensional liquid chromatography-tandem mass spectrometry.

RESULTS

Overall, 1340 proteins were identified. Of these, biomarker candidates were selected based on P-value (<0.001), changes in protein expression (≥1.5-fold increase or decrease), and unique peptides identified (≥2). Three comparisons made between BRONJ and control patients identified 200 proteins to be differentially expressed in BRONJ patients. A majority of these proteins were predicted to have a role in drug metabolism and immunological and dermatological diseases. Of all the differentially expressed proteins, we selected metalloproteinase-9 and desmoplakin for further validation. Immunoassays confirmed increased expression of metalloproteinase-9 in individual saliva (P = 0.048) and serum samples (P = 0.05) of BRONJ patients. Desmoplakin was undetectable in saliva. However, desmoplakin levels tended to be lower in BRONJ serum than controls (P = 0.157).

CONCLUSIONS

Multiple pathological reactions are involved in BRONJ development. One or more proteins identified by this study may prove to be useful biomarkers for BRONJ diagnosis. The role of metalloproteinase-9 and desmoplakin in BRONJ requires further investigation.

Loss of the p53/p63 target PERP is an early event in oral carcinogenesis and correlates with higher rate of local relapse

BACKGROUND

PERP is a p53/p63-regulated gene encoding a desmosomal protein that plays a critical role in cell-cell adhesion and tumor suppression.

STUDY DESIGN

We evaluated PERP expression in different grades of oral dysplasia (34 cases) and at different stages of invasive squamous cell carcinoma (SCC), and correlated the latter with clinical outcome. A tissue microarray consisting of nondysplastic mucosa, carcinoma in situ, SCC, and nodal metastases from 33 patients with human papilloma virus-negative SCC was stained for PERP and E-cadherin.

RESULTS

Complete loss of PERP expression was associated with worse local control in patients with SCC. The 5-year local control rate was 91% for patients with partial PERP loss versus 31% for those with complete loss (P = .01).

CONCLUSIONS

This is the first study to show that loss of PERP expression correlates with the transition to SCC and with increased local relapse in patients with oral cavity SCC.

Transmembrane protein PERP is a component of tessellate junctions and of other junctional and non-junctional plasma membrane regions in diverse epithelial and epithelium-derived cells

Protein PERP (p53 apoptosis effector related to PMP-22) is a small (21.4 kDa) transmembrane polypeptide with an amino acid sequence indicative of a tetraspanin character. It is enriched in the plasma membrane and apparently contributes to cell-cell contacts. Hitherto, it has been reported to be exclusively a component of desmosomes of some stratified epithelia. However, by using a series of newly generated mono- and polyclonal antibodies, we show that protein PERP is not only present in all kinds of stratified epithelia but also occurs in simple, columnar, complex and transitional epithelia, in various types of squamous metaplasia and epithelium-derived tumors, in diverse epithelium-derived cell cultures and in myocardial tissue. Immunofluorescence and immunoelectron microscopy allow us to localize PERP predominantly in small intradesmosomal locations and in variously sized, junction-like peri- and interdesmosomal regions ("tessellate junctions"), mostly in mosaic or amalgamated combinations with other molecules believed, to date, to be exclusive components of tight and adherens junctions. In the heart, PERP is a major component of the composite junctions of the intercalated disks connecting cardiomyocytes. Finally, protein PERP is a cobblestone-like general component of special plasma membrane regions such as the bile canaliculi of liver and subapical-to-lateral zones of diverse columnar epithelia and upper urothelial cell layers. We discuss possible organizational and architectonic functions of protein PERP and its potential value as an immunohistochemical diagnostic marker.

p63 steps into the limelight: crucial roles in the suppression of tumorigenesis and metastasis

The role of p63 in cancer has been an area of intense debate and controversy. Is TP63 (which encodes p63) a tumour suppressor gene or an oncogene? This debate is partly due to the complexity of the gene. There are several p63 isoforms - some with tumour suppressive functions and others with oncogenic functions. In this Opinion article, we focus on the recent advances in understanding p63 biology and its roles in cancer. In this regard, we discuss the role of p63 in multiple stem cell compartments, ageing, in the response to DNA damage and in DNA repair. Finally, we highlight the importance of understanding the interactions between all three p53 family members and the potential impact of this knowledge on cancer therapy and regenerative medicine.

Structure, function, and regulation of desmosomes

Desmosomes are adhesive intercellular junctions that mechanically integrate adjacent cells by coupling adhesive interactions mediated by desmosomal cadherins to the intermediate filament cytoskeletal network. Desmosomal cadherins are connected to intermediate filaments by densely clustered cytoplasmic plaque proteins comprising members of the armadillo gene family, including plakoglobin and plakophilins, and members of the plakin family of cytolinkers, such as desmoplakin. The importance of desmosomes in tissue integrity is highlighted by human diseases caused by mutations in desmosomal genes, autoantibody attack of desmosomal cadherins, and bacterial toxins that selectively target desmosomal cadherins. In addition to reviewing the well-known roles of desmosomal proteins in tissue integrity, this chapter also highlights the growing appreciation for how desmosomal proteins are integrated with cell signaling pathways to contribute to vertebrate tissue organization and differentiation.

The "Sharp" blade against HIF-mediated metastasis

Hypoxia-inducible factors (HIFs) control cellular adaptation to oxygen deprivation. Cancer cells engage HIFs to sustain their growth in adverse conditions, thus promoting a cellular reprograming that includes metabolism, proliferation, survival and mobility. HIFs overexpression in human cancer biopsies correlates with high metastasis and mortality. A recent report has elucidated a novel mechanism for HIFs regulation in triple-negative breast cancer. Specifically, the basic helix-loop-helix (bHLH), Sharp-1, serves HIF1α to the proteasome and promotes its O₂-indendpendet degradation, counteracting HIF-mediated metastasis. These findings shed light on how HIFs are manipulated during cancer pathogenesis.

Estrogens promote cell-cell adhesion of normal and malignant mammary cells through increased desmosome formation

The association of estrogen receptor alpha (ERα) expression with differentiated breast tumors presenting a lower metastasis risk could be explained by the estrogen modulation of cell adhesion, motility and invasiveness. Since desmosomes play a crucial role in cell-cell adhesion and may interfere in tumor progression, we studied their regulation by estrogens in human breast cancer and normal mammary cells. Estrogens increased the formation of desmosomes in normal and malignant cells. Furthermore, four desmosomal proteins (desmocollin, γ-catenin, plakophilin and desmoplakin) appeared significantly up-regulated by estrogens in three ERα-expressing cancer cell lines and this effect was reversed by a pure antiestrogen. Finally, silencing of ERα or desmoplakin expression by specific siRNA revealed that estrogen-modulated desmosomal proteins are essential for the estrogenic control of intercellular adhesion. This estrogen modulation of desmosome formation could contribute to the lower invasiveness of ERα-positive tumors and to the integrity of epithelial layers in estrogen target tissues.

Unimpaired skin carcinogenesis in Desmoglein 3 knockout mice

The contribution of adherens junction inactivation, typically by downregulation or mutation of the transmembrane core component E-cadherin, to cancer progression is well recognized. In contrast, the role of the desmosomal cadherin components of the related cell-cell adhesion junction, the desmosome, in cancer development has not been well explored. Here, we use mouse models to probe the functional role of desmosomal cadherins in carcinogenesis. Because mice lacking the desmosomal cadherin Desmoglein 3 (Dsg3) have revealed a crucial role for Dsg3 in cell-cell adhesion in stratified epithelia, we investigate the consequence of Dsg3 loss in two models of skin carcinogenesis. First, using Dsg3−/− keratinocytes, we show that these cells display adhesion defects in vitro and compromised tumor growth in allograft assays, suggesting that Dsg3 enables tumor formation in certain settings. In contrast, using an autochthonous model for SCC development in response to chronic UVB treatment, we discover a surprising lack of enhanced tumorigenesis in Dsg3−/− mice relative to controls, unlike mice lacking the desmosomal component Perp. Accordingly, there is no defect in the apoptotic response to UVB or enhanced immune cell infiltration upon Dsg3 loss that could promote tumorigenesis. Thus, Dsg3 does not display a clear function as a tumor suppressor in these mouse skin cancer models. Continued unraveling of the roles of Dsg3 and other desmosomal constituents in carcinogenesis in different contexts will be important for ultimately improving cancer diagnosis, prognostication, and treatment.

Dose-related estrogen effects on gene expression in fetal mouse prostate mesenchymal cells

Developmental exposure of mouse fetuses to estrogens results in dose-dependent permanent effects on prostate morphology and function. Fetal prostatic mesenchyme cells express estrogen receptor alpha (ERα) and androgen receptors and convert stimuli from circulating estrogens and androgens into paracrine signaling to regulate epithelial cell proliferation and differentiation. To obtain mechanistic insight into the role of different doses of estradiol (E2) in regulating mesenchymal cells, we examined E2-induced transcriptomal changes in primary cultures of fetal mouse prostate mesenchymal cells. Urogenital sinus mesenchyme cells were obtained from male mouse fetuses at gestation day 17 and exposed to 10 pM, 100 pM or 100 nM E2 in the presence of a physiological concentration of dihydrotestosterone (0.69 nM) for four days. Gene ontology studies suggested that low doses of E2 (10 pM and 100 pM) induce genes involved in morphological tissue development and sterol biosynthesis but suppress genes involved in growth factor signaling. Genes involved in cell adhesion were enriched among both up-regulated and down-regulated genes. Genes showing inverted-U-shape dose responses (enhanced by E2 at 10 pM E2 but suppressed at 100 pM) were enriched in the glycolytic pathway. At the highest dose (100 nM), E2 induced genes enriched for cell adhesion, steroid hormone signaling and metabolism, cytokines and their receptors, cell-to-cell communication, Wnt signaling, and TGF- β signaling. These results suggest that prostate mesenchymal cells may regulate epithelial cells through direct cell contacts when estrogen level is low whereas secreted growth factors and cytokines might play significant roles when estrogen level is high.

Integrative analysis reveals an outcome-associated and targetable pattern of p53 and cell cycle deregulation in diffuse large B cell lymphoma

Diffuse large B cell lymphoma (DLBCL) is a clinically and biologically heterogeneous disease with a high proliferation rate. By integrating copy number data with transcriptional profiles and performing pathway analysis in primary DLBCLs, we identified a comprehensive set of copy number alterations (CNAs) that decreased p53 activity and perturbed cell cycle regulation. Primary tumors either had multiple complementary alterations of p53 and cell cycle components or largely lacked these lesions. DLBCLs with p53 and cell cycle pathway CNAs had decreased abundance of p53 target transcripts and increased expression of E2F target genes and the Ki67 proliferation marker. CNAs of the CDKN2A-TP53-RB-E2F axis provide a structural basis for increased proliferation in DLBCL, predict outcome with current therapy, and suggest targeted treatment approaches.

Gene expression profiling identifies ESRP1 as a potential regulator of epithelial mesenchymal transition in somatotroph adenomas from a large cohort of patients with acromegaly

CONTEXT

The epithelial marker E-cadherin plays a crucial role in epithelial-mesenchymal transition (EMT). Decreased protein content in somatotroph adenomas has been associated with increased tumor size, invasion, and poor response to somatostatin analog (SA) treatment, but the potential mechanisms of EMT progression in these adenomas are lacking.

OBJECTIVE

We hypothesized that characterization of EMT-related transcripts in somatotroph adenomas could identify novel therapeutic targets in individuals with poor response to SA treatment and provide more knowledge of the mechanism of EMT progression.

PATIENTS

Fifty-three patients with acromegaly participated in the study.

RESEARCH DESIGN AND METHODS

We performed microarray analysis of 16 adenomas, eight with high expression and eight with low expression of E-cadherin, in order to identify EMT-related transcripts. Candidate transcripts were further explored in vivo in 53 adenomas and in vitro in a rat pituitary GH-producing cell (GH3) after exploring three models for reducing E-cadherin and inducing a mesenchymal phenotype.

RESULTS

In vivo E-cadherin mRNA expression in tumor tissue is associated negatively with tumor size and invasiveness and positively with GH and IGF-I levels in serum and response to SA treatment. Microarray and subsequent PCR analysis identify several EMT-related genes associated with E-cadherin expression. In vitro, few of these EMT-related genes were regulated by silencing E-cadherin or by TGF-β1 treatment in GH3 cells. In contrast, silencing Esrp1 in GH3 cells regulated many of the EMT-related transcripts.

CONCLUSION

These results indicate that ESRP1 could be a master regulator of the EMT process in pituitary adenomas causing acromegaly.