Revisiting Histone Deacetylases in Human Tumorigenesis: The Paradigm of Urothelial Bladder Cancer

Transcriptome-Based Network Analysis Related to Histone Deacetylase Genes and Identified EMP1 as a Potential Biomarker for Prognosis in Bladder Cancer

BACKGROUND

Abnormal expression and function of histone deacetylases (HDACs) are closely associated with the development of bladder cancer (BCa). Systematic elucidation of the role of HDACs in BCa is expected to improve BCa prognosis and treatment strategies.

METHODS

We explored the correlation and expression patterns of HDAC family genes in BCa. Consensus clustering was employed to categorize BCa into subtypes based on HDAC expression profiles. Differential analysis, pathway enrichment analysis, and drug responsiveness evaluation were conducted to characterize HDAC subtypes. Then, a prognostic model based on HDAC cluster related genes was constructed and validated across multiple cohorts.

RESULTS

We identified distinct HDAC expression patterns and correlations with immune cell infiltration and enrichment of pathways in cancer, highlighting their role in BCa. Consensus clustering revealed 2 HDAC gene subtypes. Gene cluster 1 showed worse survival, higher clinical stage, and lower immune cell infiltration compared to gene cluster 2. Additionally, pathway enrichment analysis revealed differences in tumor-promoting pathways between the clusters. Moreover, gene cluster 1 exhibited higher resistance to Rho kinase inhibitor drugs. Multi-omic analysis unveiled unique mutation and CNV profiles between the clusters, indicating distinct molecular features. Furthermore, a HDAC gene-related prognostic model demonstrated robust predictive accuracy and identified EMP1 as a key prognostic gene associated with poor survival and enriched metastatic pathways.

CONCLUSION

Our study provides comprehensive insights into the landscape of HDACs in BCa, elucidating their roles in tumor heterogeneity, immune modulation, drug responsiveness, and molecular features. EMP1 is a potential therapeutic target and prognostic marker for BCa.

Potential clinical application of microRNAs in bladder cancer

Bladder cancer (BC) is the tenth most prevalent malignancy globally, presenting significant clinical and societal challenges because of its high incidence, rapid progression, and frequent recurrence. Presently, cystoscopy and urine cytology serve as the established diagnostic methods for BC. However, their efficacy is limited by their invasive nature and low sensitivity. Therefore, the development of highly specific biomarkers and effective non-invasive detection strategies is imperative for achieving a precise and timely diagnosis of BC, as well as for facilitating an optimal tumor treatment and an improved prognosis. microRNAs (miRNAs), short noncoding RNA molecules spanning around 20-25 nucleotides, are implicated in the regulation of diverse carcinogenic pathways. Substantially altered miRNAs form robust functional regulatory networks that exert a notable influence on the tumorigenesis and progression of BC. Investigations into aberrant miRNAs derived from blood, urine, or extracellular vesicles indicate their potential roles as diagnostic biomarkers and prognostic indicators in BC, enabling miRNAs to monitor the progression and predict the recurrence of the disease. Simultaneously, the investigation centered on miRNA as a potential therapeutic agent presents a novel approach for the treatment of BC. This review comprehensively analyzes biological roles of miRNAs in tumorigenesis and progression, and systematically summarizes their potential as diagnostic and prognostic biomarkers, as well as therapeutic targets for BC. Additionally, we evaluate the progress made in laboratory techniques within this field and discuss the prospects.

Epigenetic and Genetic Keys to Fight HPV-Related Cancers

Cervical cancer ranks as the fourth most prevalent cancer among women globally, with approximately 600,000 new cases being diagnosed each year. The principal driver of cervical cancer is the human papillomavirus (HPV), where viral oncoproteins E6 and E7 undertake the role of driving its carcinogenic potential. Despite extensive investigative efforts, numerous facets concerning HPV infection, replication, and pathogenesis remain shrouded in uncertainty. The virus operates through a variety of epigenetic mechanisms, and the epigenetic signature of HPV-related tumors is a major bottleneck in our understanding of the disease. Recent investigations have unveiled the capacity of viral oncoproteins to influence epigenetic changes within HPV-related tumors, and conversely, these tumors exert an influence on the surrounding epigenetic landscape. Given the escalating occurrence of HPV-triggered tumors and the deficiency of efficacious treatments, substantial challenges emerge. A promising avenue to address this challenge lies in epigenetic modulators. This review aggregates and dissects potential epigenetic modulators capable of combatting HPV-associated infections and diseases. By delving into these modulators, novel avenues for therapeutic interventions against HPV-linked cancers have come to the fore.

Tackling FGFR3-driven bladder cancer with a promising synergistic FGFR/HDAC targeted therapy

Bladder cancer (BC) is one of the most prevalent malignancies worldwide and FGFR3 alterations are particularly common in BC. Despite approval of erdafitinib, durable responses for FGFR inhibitors are still uncommon and most patients relapse to metastatic disease. Given the necessity to discover more efficient therapies for BC, herein, we sought to explore promising synergistic combinations for BC with FGFR3 fusions. Our studies confirmed the synergy between FGFR and HDAC inhibitors in vitro and demonstrated its benefits in vivo. Mechanistic studies revealed that quisinostat can downregulate FGFR3 expression by suppressing FGFR3 translation. Additionally, quisinostat can also sensitize BC cells to erdafitinib by downregulating HDGF. Furthermore, the synergy was also confirmed in BC cells with FGFR3 S249C. This study discovers a new avenue for treatment of FGFR3-driven BC and uncovers new mechanistic insights. These preclinical studies pave the way for a direct translation of this combination to early phase clinical trials.

Are inhibitors of histone deacetylase 8 (HDAC8) effective in hematological cancers especially acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL)?

Histone deacetylase 8 (HDAC8) aberrantly deacetylates histone and non-histone proteins. These include structural maintenance of chromosome 3 (SMC3) cohesin protein, retinoic acid induced 1 (RAI1), p53, etc and thus, regulating diverse processes such as leukemic stem cell (LSC) transformation and maintenance. HDAC8, one of the crucial HDACs, affects the gene silencing process in solid and hematological cancer progressions especially on acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). A specific HDAC8 inhibitor PCI-34051 showed promising results against both T-cell lymphoma and AML. Here, we summarize the role of HDAC8 in hematological malignancies, especially in AML and ALL. This article also introduces the structure/function of HDAC8 and a special attention has been paid to address the HDAC8 enzyme selectivity issue in hematological cancer especially against AML and ALL.

Implication of KDM6A in bladder cancer

Background: Bladder cancer is a common urogenital malignancy characterized by frequent genetic alterations. Histone demethylase gene KDM6A is commonly mutated in bladder cancer. Aim: To review the characteristics of KDM6A and its mutation consequences, and to introduce a potential KDM6A-targeted treatment. Methods: We conducted a comprehensive literature search using two electronic databases, MEDLINE and Cochrane Library, to retrieve topic-related articles from July 2013 to July 2022 using keywords 'KDM6A', 'bladder cancer', 'UTX', 'treatment' and 'mutation'. Five reviewers independently screened literature search results and abstracted data from included studies. Descriptive analysis was conducted and 30 articles were retained. Main Results: A total of 30 articles were retrieved. Experimental and clinical data were collected and grouped by theme. Therapeutic strategies are depicted and organized by tables for a better understanding. Conclusion: This review demonstrates that KDM6A has crucial implications in bladder cancer pathogenesis and treatment.

Recent development of urinary biomarkers for bladder cancer diagnosis and monitoring

Urine‐based liquid biopsy has emerged as a non‐invasive and effective tool for early screening and diagnosis of bladder cancer. This review provides a comprehensive overview of the current urine‐based biomarkers and methods for the detection and monitoring of bladder cancer. We focus on biomarkers including tumour DNAs, proteins, microbiome, tumour RNAs, long non‐coding RNAs, transfer RNA‐derived fragments, messenger RNAs, microRNAs, circular RNAs, exosomes and extrachromosomal circular DNA.

New Approaches to Targeting Epigenetic Regulation in Bladder Cancer

Epigenetics is a growing field and in bladder cancer, it is of particular interest in advanced or metastatic disease. As opposed to genetic mutations in which the nucleotide sequence itself is altered, epigenetic alterations refer to changes to the genome that do not involve nucleotides. This is of great interest in cancer research because epigenetic alterations are reversible, making them a promising target for pharmacological agents. While chemoimmunotherapy is the mainstay for metastatic disease, there are few alternatives for patients who have progressed on first- or second-line treatment. By targeting reversible epigenetic alterations, novel epigenetic therapies are important potential treatment options for these patients. A search of clinical registries was performed in order to identify and collate epigenetic therapies currently in human trials. A literature search was also performed to identify therapies that are currently in preclinical stages, whether this be in vivo or in vitro models. Twenty-five clinical trials were identified that investigated the use of epigenetic inhibitors in patients with bladder cancer, often in combination with another agent, such as platinum-based chemotherapy or pembrolizumab. The main classes of epigenetic inhibitors studied include DNA-methyltransferase (DNMT) inhibitors, histone deacetylase (HDAC) inhibitors, and histone methyltransferase (HMT) inhibitors. At present, no phase 3 clinical trials have been registered. Few trials have published results, though DNMT inhibitors have shown the most promise thus far. Many patients with advanced or metastatic bladder cancer have limited treatment options, particularly when first- or second-line chemoimmunotherapy fails. Epigenetic alterations, which are common in bladder cancer, are potential targets for drug therapies, and these epigenetic agents are already in use for many cancers. While they have shown promise in pre-clinical trials for bladder cancer, more research is needed to assess their benefit in clinical settings.

The expression of HDAC9 and P300 in papillary thyroid carcinoma cell line

PURPOSE

Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer and accounts for 85-90% of all thyroid cancers. Metastatic differentiated thyroid cancer, radioiodine-refractory thyroid cancer, and anaplastic thyroid cancer still lack effective therapeutic options. Here, we aimed to assess HDAC9 and P300 expression in the papillary thyroid carcinoma cell line and compare them with normal thyroid cells.

METHODS

Nthy-ori-3-1, a normal thyroid cell line, and BCPAP, a PTC cell line, were cultured for 24 and 48 h and immunofluorescence staining was used to determine the levels of HDAC9 and P300 protein expression. HDAC9 paracrine release was assessed using an ELISA assay.

RESULTS

HDAC9 protein expression was higher in both cell groups at the 48th hour than at the 24th hour; however, P300 protein expression was lower in BCPAP cells at the 48th hour than at the 24th hour. In comparison to Nthy-ori-3-1, BCPAP expressed more HDAC9 and P300 proteins. HDAC9 secretion slightly increased in Nthy-ori-3-1 cells from 24 to 48 h. Furthermore, HDAC9 secretion in BCPAP cells dramatically decreased from 24 to 48 h.

CONCLUSION

Our findings revealed that the expression of HDAC9 and P300 was higher in the PTC cell line than in normal thyroid cells. This indicates that the acetylation mechanism in thyroid cancer cells is not the same as it is in healthy cells. Epigenetic studies may reveal the mechanisms underlying PTC with further analysis.

Regulation of cisplatin resistance in bladder cancer by epigenetic mechanisms

Bladder cancer is one of the most common malignancies in the world. Cisplatin is one of the most potent and widely used anticancer drugs and has been employed in several malignancies. Cisplatin-based combination chemotherapies have become important adjuvant therapies for bladder cancer patients. Cisplatin-based treatment often results in the development of chemoresistance, leading to therapeutic failure and limiting its application and effectiveness in bladder cancer. To develop improved and more effective cancer therapy, research has been conducted to elucidate the underlying mechanism of cisplatin resistance. Epigenetic modifications have been demonstrated involved in drug resistance to chemotherapy, and epigenetic biomarkers, such as urine tumor DNA methylation assay, have been applied in patients screening or monitoring. Here, we provide a systematic description of epigenetic mechanisms, including DNA methylation, noncoding RNA regulation, m6A modification and posttranslational modifications, related to cisplatin resistance in bladder cancer.

Epigenetic Priming and Development of New Combination Therapy Approaches

Muscle-invasive urothelial carcinoma of the bladder (MIBC) has been treated with cisplatin-based chemotherapy for over 30 years. With the advent of immune checkpoint inhibitors, antibody drug conjugates and FGFR3 inhibitors new therapeutic options have been approved for patients with urothelial carcinoma (UC) and are still under investigation regarding association between patients' response and recently defined molecular subtypes. Unfortunately, similar to chemotherapy, only a fraction of UC patients responds to these new treatment approaches. Thus, either further new efficacious therapeutic options for treatment of individual subtypes or new approaches to overcome treatment resistance and to increase patients' response to standard of care treatment are needed.Epigenetic modifications of DNA and chromatin are known to mediate cellular plasticity or treatment resistance, and the responsible epigenetic regulators are frequently mutated or aberrantly expressed in UC. Thus, these enzymes provide targets for novel drug combination therapies to "episensitize" toward approved standard therapies by epigenetic priming. In general, these epigenetic regulators comprise writers and erasers like DNA methyltransferases and DNA demethylases (for DNA methylation), histone methyltransferases and histone demethylases (for histone methylation), as well as acetyl transferases and histone deacetylases (for histone and nonhistone acetylation). Such modifications, e.g., acetyl groups, are recognized by further epigenetic reader proteins, e.g., like the bromodomain and extra-terminal domain (BET) family proteins that often interact in multi-protein complexes and finally regulate chromatin conformation and transcriptional activity.Concurringly, epigenetic regulators target a plethora of cellular functions. Their pharmaceutical inhibitors often inhibit enzymatic activity of more than one isoenzyme or may have further noncanonical cytotoxic effects. Thus, analysis of their functions in UC pathogenesis as well as of the antineoplastic capacity of corresponding inhibitors alone or in combination with other approved drugs should follow a multidimensional approach. Here, we present our standard approach to analyze cellular effects of new epigenetic inhibitors on UC cells alone to define their potency and to conclude on putative reasonable combination therapy partners. We further describe our approach to identify efficacious synergistic combination therapies (e.g., with cisplatin or PARP inhibitors) that may have reduced normal toxicity through dose reduction, which can then be further analyzed in animal experiments. This approach may also serve as prototype for the preclinical evaluation of other epigenetic treatment approaches.

Valproic acid and bladder healing: an experimental study in rats

PURPOSE

to recognize the effects of valproic acid (VPA), an epigenetic drug, on the bladder healing process, in rats.

METHOD

twenty male Wistar rats were divided in two groups: experimental (A), treated with VPA (150mg/Kg/day), and control (B) with 0.9% sodium chloridrate. Healing was analyzed on the third and seventh days, evaluating the inflammatory reaction, collagen synthesis and angiogenesis.

RESULTS

inflammatory reaction on the third day was minimal and acute in both groups. On the seventh day, it was subacute in both groups, moderate intensity in group A and minimal in group B (p=0.0476). Collagen III intensity, marked by immunohistochemistry, was similar in both groups. Collagen I intensity on the third day was similar in both groups, but on the seventh day it was higher in experimental than control (p=0.0476). Collagen evaluation by picrosiriusred allowed to verify that the presence of collagen III was similar in both groups (p=0.3312) on the third day, and it was higher in control on the seventh day (p=0.0015). Collagen I showed similarity on the third day (p=0.3100), and it was higher in control on the seventh day (p=0.0015). Vessel marked with anti-SMA counting showed fewer vessels on the third (p=0.0034) and seventh day (p=0.0087) in experimental group. The lower intensity of angiogenesis was confirmed with anti-CD34, on the third day (p=0,0006) and on the seventh day (p=0,0072).

CONCLUSION

VPA determined alterations in the bladder healing process, in rats, with lower collagen density and less angiogenic activity, but without compromising the integrity of the organ.

Repression of the PRELP gene is relieved by histone deacetylase inhibitors through acetylation of histone H2B lysine 5 in bladder cancer

BACKGROUND

Proline/arginine-rich end leucine-rich repeat protein (PRELP) is a member of the small leucine-rich proteoglycan family of extracellular matrix proteins, which is markedly suppressed in the majority of early-stage epithelial cancers and plays a role in regulating the epithelial-mesenchymal transition by altering cell-cell adhesion. Although PRELP is an important factor in the development and progression of bladder cancer, the mechanism of PRELP gene repression remains unclear.

RESULTS

Here, we show that repression of PRELP mRNA expression in bladder cancer cells is alleviated by HDAC inhibitors (HDACi) through histone acetylation. Using ChIP-qPCR analysis, we found that acetylation of lysine residue 5 of histone H2B in the PRELP gene promoter region is a marker for the de-repression of PRELP expression.

CONCLUSIONS

These results suggest a mechanism through which HDACi may partially regulate the function of PRELP to suppress the development and progression of bladder cancer. Some HDACi are already in clinical use, and the findings of this study provide a mechanistic basis for further investigation of HDACi-based therapeutic strategies.

Identification of Epigenetic Interactions between miRNA and Gene Expression as Potential Prognostic Markers in Bladder Cancer

Purpose: To identify the role of a set of microRNAs and their target genes and protein expression levels in the pathogenesis of bladder cancer with a muscular invasion (T2−T4) and non-muscular invasion (T1). Methods: In 157 patients, bladder specimen was examined for the expression of a set of miRNAs including let-7a-5p, miRNA-449a-5p, miRNA-145-3P, miRNA-124-3P, miRNA-138-5p, and miRNA-23a-5p and their targeted genes; β-catenin, WNT7A, IRS2, FZD4, SOS1, HDAC1, HDAC2, HIF1α, and PTEN using the qRT-PCR technique. The prognostic effect of miRNAs and their targeted genes on cancer-specific survival (CSS) was evaluated in pT2−pT4 stages. Results: pT1 was found in 40 patients while pT2−4 was found in 117 patients. The expression of let-7a-5P, miR-124-3P, miR-449a-5P, and miR-138-5P significantly decreased in pT2−4 compared with pT1 (p < 0.001), in contrast, miR-23a-5P increased significantly in pT2−pT4 compared with pT1 (p < 0.001). Moreover, the expression of miR-145 did not show a significant change (p = 0.31). Higher expression levels of WNT7A, β-catenin, IRS2, FZD4, and SOS1 genes were observed in pT2−pT4 compared with pT1, whereas HDAC1, HDAC2, HIF1α, and PTEN genes were downregulated in pT2−pT4 compared with pT1. Lower CSS was significantly associated with lower expression of let-7a-5P, miR-124-3P, miR-449a-5P, and miR-138-5P. Higher expression of β-catenin, FZD4, IRS2, WNT7a, and SOS1 was significantly associated with worse CSS. In contrast, lower levels of HDAC1, HDAC2, HIF1α, and PTEN were associated with lower CSS. Conclusion: Our results support let-7a-5P, miR-124-3P, miR-138-5P, and their target genes can be developed as accurate biomarkers for prognosis in bladder cancer with a muscular invasion.

Role of Chromatin Modifying Complexes and Therapeutic Opportunities in Bladder Cancer

BACKGROUND

Chromatin modifying enzymes, mainly through post translational modifications, regulate chromatin architecture and by extension the underlying transcriptional kinetics in normal and malignant cells. Muscle invasive bladder cancer (MIBC) has a high frequency of alterations in chromatin modifiers, with 76% of tumors exhibiting mutation in at least one chromatin modifying enzyme [1]. Additionally, clonal expansion of cells with inactivating mutations in chromatin modifiers has been identified in the normal urothelium, pointing to a currently unknown role of these proteins in normal bladder homeostasis.

OBJECTIVE

To review current knowledge of chromatin modifications and enzymes regulating these processes in Bladder cancer (BCa).

METHODS

By reviewing current literature, we summarize our present knowledge of external stimuli that trigger loss of equilibrium in the chromatin accessibility landscape and emerging therapeutic interventions for targeting these processes.

RESULTS

Genetic lesions in BCa lead to altered function of chromatin modifying enzymes, resulting in coordinated dysregulation of epigenetic processes with disease progression.

CONCLUSION

Mutations in chromatin modifying enzymes are wide-spread in BCa and several promising therapeutic targets for modulating activity of these genes are currently in clinical trials. Further research into understanding how the epigenetic landscape evolves as the disease progresses, could help identify patients who might benefit the most from these targeted therapies.

LncRNA PVT1 contributes to invasion and doxorubicin resistance of bladder cancer cells through promoting MDM2 expression and AURKB-mediated p53 ubiquitination

In most bladder cancer (BC) patients, cancer cells will eventually develop chemical resistance causing increased mortality. This study aimed to explore the mechanism of lncRNA plasmacytoma variant translocation 1 (PVT1) in regulating doxorubicin (ADM) resistance of BC cells. We observed that PVT1 expression was upregulated in ADM-resistant BC cells compared with ADM-sensitive BC cells. Downregulation of PVT1 suppressed ADM-resistant BC cell proliferation and invasion, promoted apoptosis, and increased sensitivity to ADM, while PVT1 overexpression promoted ADM-sensitive BC cell growth and their resistance to ADM. Further study uncovered that PVT1 could interact with and promote mouse double minute 2 (MDM2) expression, and upregulated MDM2-mediated Aurora kinase B (AURKB). Furthermore, Nutlin-3, an inhibitor of MDM2, could counteract the promotive effects of PVT1 overexpression on ADM resistance of ADM-sensitive BC cell, the expression of multidrug-resistance-related proteins, and the inhibition of p53-mediated tumor suppressor genes. And, overexpression of MDM2 or AURKB reversed the promotive effects of PVT1 silence on the ADM sensitivity of ADM-resistant BC cell, and the inhibitory effect on expression multidrug resistance proteins. Mechanically, AURKB increased MDM2-mediated p53 ubiquitination. Taken together, PVT1 promoted BC cell proliferation and drug resistance via elevating MDM2 expression and AURKB-mediated p53 ubiquitination.

Proteomic and transcriptomic profiles of human urothelial cancer cells with histone deacetylase 5 overexpression

Urothelial carcinoma (UC) of the urinary bladder is a prevalent cancer worldwide. Because histone deacetylases (HDACs) are important factors in cancer, targeting these epigenetic regulators is considered an attractive strategy to develop novel anticancer drugs. Whereas HDAC1 and HDAC2 promote UC, HDAC5 is often downregulated and only weakly expressed in UC cell lines, suggesting a tumor-suppressive function. We studied the effect of stable lentiviral-mediated HDAC5 overexpression in four UC cell lines with different phenotypes (RT112, VM-Cub-1, SW1710, and UM-UC-3, each with vector controls). In particular, comprehensive proteomics and RNA-seq transcriptomics analyses were performed on the four cell line pairs, which are described here. For comparison, the immortalized benign urothelial cell line HBLAK was included. These datasets will be a useful resource for researchers studying UC, and especially the influence of HDAC5 on epithelial-mesenchymal transition (EMT). Moreover, these data will inform studies on HDAC5 as a less studied member of the HDAC family in other cell types and diseases, especially fibrosis.

Gene network profiling in muscle-invasive bladder cancer: A systematic review and meta-analysis

BACKGROUND

Determining meta-analysis of transcriptional profiling of muscle-invasive bladder cancer (MIBC) through Gene Expression Omnibus (GEO) datasets has not been investigated. This study aims to define gene expression profiles in MIBC and to identify potential candidate genes and pathways.

OBJECTIVES

To review and evaluate gene expression studies in MIBC through publicly available RNA sequencing (RNA-Seq) and microarray data in order to identify potential prognostic and therapeutic targets for MIBC.

METHODS

A systematic literature search of the Ovid MEDLINE, PubMed, and Wiley Cochrane Central Register of Controlled Trials databases was performed using the terms "gene," "gene expression," and "bladder cancer" January 1, 1990 through March 2021 focused on populations with MIBC.

RESULTS

In the final analysis, GEO datasets were included. Fixed effect model was employed in the meta-analysis. Gene networking connections and gene-set functional analyses of the identified genes as differentially expressed in MIBC were performed using ImaGEO and GeneMANIA software. A heatmap for the upregulated and downregulated genes was generated along with the correlated pathways.

CONCLUSION

A total of 9 genes were reported in this analysis. Six genes were reported as upregulated (ProTα, SPINT1, UBE2E1, RAB25, KPNB1, HDAC1) and 3 genes as downregulated (NUP188, IPO13, NUP124). Genes were found to be involved in "ubiquitin mediated proteolysis," "protein processing in endoplasmic reticulum," "transcriptional misregulation in cancer," and "RNA transport" pathways.

The Potential Role of Mitochondrial Acetaldehyde Dehydrogenase 2 in Urological Cancers From the Perspective of Ferroptosis and Cellular Senescence

Overproduction of reactive oxygen species (ROS) and superlative lipid peroxidation promote tumorigenesis, and mitochondrial aldehyde dehydrogenase 2 (ALDH2) is associated with the detoxification of ROS-mediated lipid peroxidation-generated reactive aldehydes such as 4-hydroxy-2-nonenal (4-HNE), malondialdehyde, and acrolein due to tobacco smoking. ALDH2 has been demonstrated to be highly associated with the prognosis and chemoradiotherapy sensitivity of many types of cancer, including leukemia, lung cancer, head and neck cancer, esophageal cancer, hepatocellular cancer, pancreatic cancer, and ovarian cancer. In this study, we explored the possible relationship between ALDH2 and urological cancers from the aspects of ferroptosis, epigenetic alterations, proteostasis, mitochondrial dysfunction, and cellular senescence.

Gemcitabine-Resistant Biomarkers in Bladder Cancer are Associated with Tumor-Immune Microenvironment

To identify key biomarkers in gemcitabine (GEM)-resistant bladder cancer (BCa) and investigate their associations with tumor-infiltrating immune cells in a tumor immune microenvironment, we performed the present study on the basis of large-scale sequencing data. Expression profiles from the Gene Expression Omnibus GSE77883 dataset and The Cancer Genome Atlas BLCA dataset were analyzed. Both BCa development and GEM-resistance were identified to be immune-related through evaluating tumor-infiltrating immune cells. Eighty-two DEGs were obtained to be related to GEM-resistance. Functional enrichment analysis demonstrated they were related to regulation of immune cells proliferation. Protein-protein interaction network selected six key genes (CAV1, COL6A2, FABP4, FBLN1, PCOLCE, and CSPG4). Immunohistochemistry confirmed the down-regulation of the six key genes in BCa. Survival analyses revealed the six key genes were significantly associated with BCa overall survival. Correlation analyses revealed the six key genes had high infiltration of most immune cells. Gene set enrichment analysis further detected the key genes might regulate GEM-resistance through immune response and drug metabolism of cytochrome P450. Next, microRNA-gene regulatory network identified three key microRNAs (hsa-miR-124-3p, hsa-miR-26b-5p, and hsa-miR-192-5p) involved in GEM-resistant BCa. Connectivity Map analysis identified histone deacetylase inhibitors might circumvent GEM-resistance. In conclusion, CAV1, COL6A2, FABP4, FBLN1, PCOLCE, and CSPG4 were identified to be critical biomarkers through regulating the immune cell infiltration in an immune microenvironment of GEM-resistance and could act as promising treatment targets for GEM-resistant muscle-invasive BCa.

Ácido valpróico e cicatrização em bexiga: estudo experimental em ratos

RESUMO Objetivo: reconhecer os efeitos do ácido valpróico (VPA), uma droga epigenética, no processo de cicatrização da bexiga, em ratos. Método: vinte ratos Wistar machos foram divididos em dois grupos: experimental (A), utilizando VPA (150mg/Kg/dia), e controle (B), tratados com cloreto de sódio 0,9% por gavagem. A cicatrização da bexiga foi analisada no terceiro e sétimo dia, estudando-se a reação inflamatória, síntese de colágeno, reepitelização e angiogênese. Resultados: a reação inflamatória no terceiro dia foi mínima e aguda em ambos os grupos. No sétimo dia, foi subaguda em ambos os grupos com intensidade moderada no grupo A e mínima no grupo B (p=0,0476). A intensidade do colágeno III, marcada pela imuno-histoquímica, foi semelhante nos dois grupos, nos dois tempos estudados. A intensidade de colágeno I no terceiro dia foi semelhante nos dois grupos, e maior no sétimo dia no grupo experimental (p=0,0476). A avaliação do colágeno pelo picrosiriusred mostrou que a presença de colágeno III foi semelhante em ambos os grupos (p=0,3312) no terceiro dia, e maior no controle no sétimo dia (p=0,0015). O colágeno I foi semelhante no terceiro dia (p=0,3100), e maior no controle no sétimo dia (p=0,0015). A contagem de vasos marcados pelo anti-SMA mostrou menos vasos no terceiro (p=0,0034) e sétimo dia (p=0,0087) no grupo experimental, confirmado pelo anti-CD34, no terceiro (p=00006) e no sétimo dia (p=0,0072). Conclusão: o VPA determinou alterações no processo de cicatrização da bexiga, em ratos, com menor densidade de colágeno e menor atividade angiogênica, mas sem comprometer a integridade do órgão.

Unraveling the Epigenetic Role and Clinical Impact of Histone Deacetylases in Neoplasia

Histone deacetylases (HDACs) have long been implicated in tumorigenesis and tumor progression demonstrating their important participation in neoplasia. Therefore, numerous studies have been performed, highlighting the mechanism of HDACs action in tumor cells and demonstrating the potential role of HDAC inhibitors in the treatment of different cancer types. The outcome of these studies further delineated and strengthened the solid role that HDACs and epigenetic modifications exert in neoplasia. These results have spread promise regarding the potential use of HDACs as prospective therapeutic targets. Nevertheless, the clinical significance of HDAC expression and their use as biomarkers in cancer has not been extensively elucidated. The aim of our study is to emphasize the clinical significance of HDAC isoforms expression in different tumor types and the correlations noted between the clinicopathological parameters of tumors and patient outcomes. We further discuss the obstacles that the next generation HDAC inhibitors need to overcome, for them to become more potent.

Epigenomic and Metabolomic Integration Reveals Dynamic Metabolic Regulation in Bladder Cancer

Bladder cancer (BC) represents a clinical, social, and economic challenge due to tumor-intrinsic characteristics, limitations of diagnostic techniques and a lack of personalized treatments. In the last decade, the use of liquid biopsy has grown as a non-invasive approach to characterize tumors. Moreover, the emergence of omics has increased our knowledge of cancer biology and identified critical BC biomarkers. The rewiring between epigenetics and metabolism has been closely linked to tumor phenotype. Chromatin remodelers interact with each other to control gene silencing in BC, but also with stress-inducible factors or oncogenic signaling cascades to regulate metabolic reprogramming towards glycolysis, the pentose phosphate pathway, and lipogenesis. Concurrently, one-carbon metabolism supplies methyl groups to histone and DNA methyltransferases, leading to the hypermethylation and silencing of suppressor genes in BC. Conversely, α-KG and acetyl-CoA enhance the activity of histone demethylases and acetyl transferases, increasing gene expression, while succinate and fumarate have an inhibitory role. This review is the first to analyze the interplay between epigenome, metabolome and cell signaling pathways in BC, and shows how their regulation contributes to tumor development and progression. Moreover, it summarizes non-invasive biomarkers that could be applied in clinical practice to improve diagnosis, monitoring, prognosis and the therapeutic options in BC.

Selective Targeting of Epigenetic Readers and Histone Deacetylases in Autoimmune and Inflammatory Diseases: Recent Advances and Future Perspectives

Histone deacetylases (HDACs) and bromodomain-containing proteins (BCPs) play a key role in chromatin remodeling. Based on their ability to regulate inducible gene expression in the context of inflammation and cancer, HDACs and BCPs have been the focus of drug discovery efforts, and numerous small-molecule inhibitors have been developed. However, dose-limiting toxicities of the first generation of inhibitors, which typically target multiple HDACs or BCPs, have limited translation to the clinic. Over the last decade, an increasing effort has been dedicated to designing class-, isoform-, or domain-specific HDAC or BCP inhibitors, as well as developing strategies for cell-specific targeted drug delivery. Selective inhibition of the epigenetic modulators is helping to elucidate the functions of individual epigenetic proteins and has the potential to yield better and safer therapeutic strategies. In accordance with this idea, several in vitro and in vivo studies have reported the ability of more selective HDAC/BCP inhibitors to recapitulate the beneficial effects of pan-inhibitors with less unwanted adverse events. In this review, we summarize the most recent advances with these strategies, discussing advantages and limitations of these approaches as well as some therapeutic perspectives, focusing on autoimmune and inflammatory diseases.

Epigenetic modulation and understanding of HDAC inhibitors in cancer therapy

The role of genetic and epigenetic factors in tumor initiation and progression is well documented. Histone deacetylases (HDACs), histone methyl transferases (HMTs), and DNA methyl transferases. (DNMTs) are the main proteins that are involved in regulating the chromatin conformation. Among these, histone deacetylases (HDAC) deacetylate the histone and induce gene repression thereby leading to cancer. In contrast, histone acetyl transferases (HATs) that include GCN5, p300/CBP, PCAF, Tip 60 acetylate the histones. HDAC inhibitors are potent drug molecules that can induce acetylation of histones at lysine residues and induce open chromatin conformation at tumor suppressor gene loci and thus resulting in tumor suppression. The key processes regulated by HDAC inhibitors include cell-cycle arrest, chemo-sensitization, apoptosis induction, upregulation of tumor suppressors. Even though FDA approved drugs are confined mainly to haematological malignancies, the research on HDAC inhibitors in glioblastoma multiforme and triple negative breast cancer (TNBC) are providing positive results. Thus, several combinations of HDAC inhibitors along with DNA methyl transferase inhibitors and histone methyl transferase inhibitors are in clinical trials. This review focuses on how HDAC inhibitors regulate the expression of coding and non-coding genes with specific emphasis on their anti-cancer potential.

Tackling tumor microenvironment through epigenetic tools to improve cancer immunotherapy

BACKGROUND

Epigenetic alterations are known contributors to cancer development and aggressiveness. Additional to alterations in cancer cells, aberrant epigenetic marks are present in cells of the tumor microenvironment, including lymphocytes and tumor-associated macrophages, which are often overlooked but known to be a contributing factor to a favorable environment for tumor growth. Therefore, the main aim of this review is to give an overview of the epigenetic alterations affecting immune cells in the tumor microenvironment to provoke an immunosuppressive function and contribute to cancer development. Moreover, immunotherapy is briefly discussed in the context of epigenetics, describing both its combination with epigenetic drugs and the need for epigenetic biomarkers to predict response to immune checkpoint blockage.

MAIN BODY

Combining both topics, epigenetic machinery plays a central role in generating an immunosuppressive environment for cancer growth, which creates a barrier for immunotherapy to be successful. Furthermore, epigenetic-directed compounds may not only affect cancer cells but also immune cells in the tumor microenvironment, which could be beneficial for the clinical response to immunotherapy.

CONCLUSION

Thus, modulating epigenetics in combination with immunotherapy might be a promising therapeutic option to improve the success of this therapy. Further studies are necessary to (1) understand in depth the impact of the epigenetic machinery in the tumor microenvironment; (2) how the epigenetic machinery can be modulated according to tumor type to increase response to immunotherapy and (3) find reliable biomarkers for a better selection of patients eligible to immunotherapy.

Epigenetic Regulatory Enzymes: mutation Prevalence and Coexistence in Cancers

Epigenetic regulation is an important layer of transcriptional control with the particularity to affect the broad spectrum of genome. Over the years, largely due to the substantial number of recurrent mutations, there have been hundreds of novel driver genes characterized in various cancers. Additionally, the relative contribution of two dysregulated epigenomic entities (DNA methylation and histone modifications) that gradually drive the cancer phenotype remains in the research focus. However, a complex scenario arises when the disease phenotype does not harbor any relevant mutation or an abnormal transcription level. Although the cancer landscape involves the contribution of multiple genetic and non-genetic factors, herein, we discuss specifically the mutation spectrum of epigenetically-related enzymes in cancer. In addition, we address the coexistence of these two epigenetic entities in malignant human diseases, especially cancer. We suggest that the study of epigenetically-related somatic mutations in the early cellular differentiation stage of embryonic development might help to understand their later-staged footprints in the cancer genome. Furthermore, understanding the co-occurrence and/or inverse association of different disease types and redefining the general definition of "healthy" controls could provide insights into the genome reorganization.

Review of Experimental Studies to Improve Radiotherapy Response in Bladder Cancer: Comments and Perspectives

Bladder cancer is among the top ten most common cancer types in the world. Around 25% of all cases are muscle-invasive bladder cancer, for which the gold standard treatment in the absence of metastasis is the cystectomy. In recent years, trimodality treatment associating maximal transurethral resection and radiotherapy combined with concurrent chemotherapy is increasingly used as an organ-preserving alternative. However, the use of this treatment is still limited by the lack of biomarkers predicting tumour response and by a lack of targeted radiosensitising drugs that can improve the therapeutic index, especially by limiting side effects such as bladder fibrosis. In order to improve the bladder-preserving treatment, experimental studies addressing these main issues ought to be considered (both in vitro and in vivo studies). Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for systematic reviews, we conducted a literature search in PubMed on experimental studies investigating how to improve bladder cancer radiotherapy with different radiosensitising agents using a comprehensive search string. We made comments on experimental model selection, experimental design and results, formulating the gaps of knowledge still existing: such as the lack of reliable predictive biomarkers of tumour response to chemoradiation according to the molecular tumour subtype and lack of efficient radiosensitising agents specifically targeting bladder tumour cells. We provided guidance to improve forthcoming studies, such as taking into account molecular characteristics of the preclinical models and highlighted the value of using patient-derived xenografts as well as syngeneic models. Finally, this review could be a useful tool to set up new radiation-based combined treatments with an improved therapeutic index that is needed for bladder preservation.

Histone Deacetylase Inhibitors from Marine Invertebrates

Histone deacetylases (HDACs) are key components of the epigenetic machinery controlling gene expression. They are involved in chromatin remodeling events via post-translational histone modifications but may also act on nonhistone proteins, influencing many fundamental cellular processes. Due to the key involvement of HDACs in serious human pathologies, including cancer, HDAC inhibitors (HDACis) have received increased attention in recent years. It is known that marine invertebrates produce significant amounts of secondary metabolites showing active pharmacological properties and an extensive spectrum of biomedical applications. The aim of this review is to gather selected studies that report the extraction and identification of marine invertebrate-derived compounds that possess HDACi properties, grouping the producing species according to their taxonomic hierarchy. The molecular, biochemical, and/or physiological aspects, where available, and modes of action of these naturally occurring HDACis will be recapitulated, taking into consideration their possible utilization for the future design of analogs with increased bioavailability and efficacy, less toxicity, and, also, higher isoform selectivity.

Bladder Cancer Metastasis Induced by Chronic Everolimus Application Can Be Counteracted by Sulforaphane In Vitro

Chronic treatment with the mTOR inhibitor, everolimus, fails long-term in preventing tumor growth and dissemination in cancer patients. Thus, patients experiencing treatment resistance seek complementary measures, hoping to improve therapeutic efficacy. This study investigated metastatic characteristics of bladder carcinoma cells exposed to everolimus combined with the isothiocyanate sulforaphane (SFN), which has been shown to exert cancer inhibiting properties. RT112, UMUC3, or TCCSUP bladder carcinoma cells were exposed short- (24 h) or long-term (8 weeks) to everolimus (0.5 nM) or SFN (2.5 µM), alone or in combination. Adhesion and chemotaxis along with profiling details of CD44 receptor variants (v) and integrin α and β subtypes were evaluated. The functional impact of CD44 and integrins was explored by blocking studies and siRNA knock-down. Long-term exposure to everolimus enhanced chemotactic activity, whereas long-term exposure to SFN or the SFN-everolimus combination diminished chemotaxis. CD44v4 and v7 increased on RT112 cells following exposure to SFN or SFN-everolimus. Up-regulation of the integrins α6, αV, and β1 and down-regulation of β4 that was present with everolimus alone could be prevented by combining SFN and everolimus. Down-regulation of αV, β1, and β4 reduced chemotactic activity, whereas knock-down of CD44 correlated with enhanced chemotaxis. SFN could, therefore, inhibit resistance-related tumor dissemination during everolimus-based bladder cancer treatment.

Chronic Sulforaphane Administration Inhibits Resistance to the mTOR-Inhibitor Everolimus in Bladder Cancer Cells

Progressive bladder cancer growth is associated with abnormal activation of the mammalian target of the rapamycin (mTOR) pathway, but treatment with an mTOR inhibitor has not been as effective as expected. Rather, resistance develops under chronic drug use, prompting many patients to lower their relapse risk by turning to natural, plant-derived products. The present study was designed to evaluate whether the natural compound, sulforaphane (SFN), combined with the mTOR inhibitor everolimus, could block the growth and proliferation of bladder cancer cells in the short- and long-term. The bladder cancer cell lines RT112, UMUC3, and TCCSUP were exposed short- (24 h) or long-term (8 weeks) to everolimus (0.5 nM) or SFN (2.5 µM) alone or in combination. Cell growth, proliferation, apoptosis, cell cycle progression, and cell cycle regulating proteins were evaluated. siRNA blockade was used to investigate the functional impact of the proteins. Short-term application of SFN and/or everolimus resulted in significant tumor growth suppression, with additive inhibition on clonogenic tumor growth. Long-term everolimus treatment resulted in resistance development characterized by continued growth, and was associated with elevated Akt-mTOR signaling and cyclin-dependent kinase (CDK)1 phosphorylation and down-regulation of p19 and p27. In contrast, SFN alone or SFN+everolimus reduced cell growth and proliferation. Akt and Rictor signaling remained low, and p19 and p27 expressions were high under combined drug treatment. Long-term exposure to SFN+everolimus also induced acetylation of the H3 and H4 histones. Phosphorylation of CDK1 was diminished, whereby down-regulation of CDK1 and its binding partner, Cyclin B, inhibited tumor growth. In conclusion, the addition of SFN to the long-term everolimus application inhibits resistance development in bladder cancer cells in vitro. Therefore, sulforaphane may hold potential for treating bladder carcinoma in patients with resistance to an mTOR inhibitor.

The Histone Deacetylase Inhibitor Romidepsin Spares Normal Tissues While Acting as an Effective Radiosensitizer in Bladder Tumors in Vivo

PURPOSE

Muscle-invasive bladder cancer has a 40% to 60% 5-year survival rate with radical treatment by surgical removal of the bladder or radiation therapy-based bladder preservation techniques, including concurrent chemoradiation. Elderly patients cannot tolerate current chemoradiation therapy regimens and often receive only radiation therapy, which is less effective. We urgently need effective chemotherapy agents for use with radiation therapy combinations that are nontoxic to normal tissues and tolerated by elderly patients.

METHODS AND MATERIALS

We have identified histone deacetylase (HDAC) inhibitors as promising agents to study. Pan-HDAC inhibition, using panobinostat, is a good strategy for radiosensitization, but more selective agents may be more useful radiosensitizers in a clinical setting, resulting in fewer systemic side effects. Herein, we study the HDAC class I-selective agent romidepsin, which we predict to have fewer off-target effects than panobinostat while maintaining an effective level of tumor radiosensitization.

RESULTS

In vitro effects of romidepsin were assessed by clonogenic assay and showed that romidepsin was effective in the nanomolar range in different bladder cancer cells and radiosensitized these cells. The radiosensitizing effect of romidepsin was confirmed in vivo using superficial xenografts. The drug/irradiation combination treatment resulted in significant tumor growth delay but did not increase the severity of acute (3.75 days) intestinal normal tissue toxicity or late toxicity at 29 weeks. Moreover, we showed that romidepsin treatment impaired both homologous recombination and nonhomologous end joining DNA repair pathways, suggesting that the disruption of DNA repair pathways caused by romidepsin is a key mechanism for its radiosensitizing effect in bladder cancer cells.

CONCLUSIONS

This study demonstrates that romidepsin is an effective radiosensitizer in vitro and in vivo and does not increase the acute and late toxicity after ionizing radiation. Romidepsin is already in clinical use for the cutaneous T-cell lymphoma, but a phase 1 clinical trial of romidepsin as a radiosensitizer could be considered in muscle-invasive bladder cancer.

Malignancy Grade-Dependent Mapping of Metabolic Landscapes in Human Urothelial Bladder Cancer: Identification of Novel, Diagnostic, and Druggable Biomarkers

Background: Urothelial bladder cancer (UBC) is one of the cancers with the highest mortality rate and prevalence worldwide; however, the clinical management of the disease remains challenging. Metabolomics has emerged as a powerful tool with beneficial applications in cancer biology and thus can provide new insights on the underlying mechanisms of UBC progression and/or reveal novel diagnostic and therapeutic schemes. Methods: A collection of four human UBC cell lines that critically reflect the different malignancy grades of UBC was employed; RT4 (grade I), RT112 (grade II), T24 (grade III), and TCCSUP (grade IV). They were examined using Nuclear Magnetic Resonance, Mass Spectrometry, and advanced statistical approaches, with the goal of creating new metabolic profiles that are mechanistically associated with UBC progression toward metastasis. Results: Distinct metabolic profiles were observed for each cell line group, with T24 (grade III) cells exhibiting the most abundant metabolite contents. AMP and creatine phosphate were highly increased in the T24 cell line compared to the RT4 (grade I) cell line, indicating the major energetic transformation to which UBC cells are being subjected during metastasis. Thymosin β4 and β10 were also profiled with grade-specific patterns of expression, strongly suggesting the importance of actin-cytoskeleton dynamics for UBC advancement to metastatic and drug-tolerant forms. Conclusions: The present study unveils a novel and putatively druggable metabolic signature that holds strong promise for early diagnosis and the successful chemotherapy of UBC disease.

Associations of sirtuins with clinicopathological variables and prognosis in human ovarian cancer

Ovarian cancer (OC) is the fifth most frequent cause of cancer-associated mortality worldwide, and is accompanied by asymptomatic progression. Sirtuins (SIRTs) are a family of nicotinamide adenine dinucleotide-dependent protein deacetylases, comprising seven members (SIRT1, SIRT2, SIRT3, SIRT4, SIRT5, SIRT6 and SIRT7). Accumulating evidence has demonstrated that SIRTs act as prognostic estimators in certain types of cancer such as lung cancer, prostate cancer, gastric cancer, breast cancer and colorectal cancer. However, it remains unknown whether individual SIRTs can serve as independent prognostic factors in OC. In the present study, the Kaplan-Meier plotter online database was utilized to examine the prognostic values of SIRT mRNA expression in patients with OC. The results demonstrated that the overexpression of SIRT3, SIRT5, SIRT6 and SIRT7 mRNAs was associated with a good prognosis in patients, whereas elevated mRNA levels of SIRT1 and SIRT4 indicated poor survival in patients with OC. In addition, among the favorable predictors, SIRT3, SIRT5, SIRT6 and SIRT7 overexpression were associated with overall survival (OS), according to clinical characteristics, such as histological classification, clinical stage, pathology grade, drug therapy and tumor protein p53 mutation status in patients with OC. Similarly, SIRT4 mRNA overexpression was associated with poor OS in pathological grade III cancer. High SIRT1 and SIRT4 expression were associated with unfavorable OS at all clinical stages. Furthermore, SIRT1 and SIRT4 were negatively associated with OS in drug-treated patients. In summary, the present study demonstrated that the SIRT family is associated with the prognosis of human OC, suggesting that individual SIRTs may also act as prognostic predictors in patients.

Characterization of Histone Deacetylase Expression Within In Vitro and In Vivo Bladder Cancer Model Systems

Epigenetic aberrations are prominent in bladder cancer (BC) and contribute to disease pathogenesis. We characterized histone deacetylase (HDAC) expression, a family of deacetylation enzymes, in both in vitro and in vivo BC model systems and analyzed expression data from The Cancer Genome Atlas (TCGA). Quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting analysis was used to determine the expression status of Class I and II HDACs in ten human BC cell lines, while qRT-PCR was used to determine HDAC expression in 24 human tumor specimens. The TCGA cohort consists of 408 muscle invasive BC (MIBC) clinical samples and analysis of this data set identified expression of HDAC4 and -9 as being associated with basal-squamous disease. These findings agree with qRT-PCR results identifying increased expression of HDAC4, -7, and -9 in basal BC cell lines (p < 0.05; Kruskal-Wallis test) and in clinical specimens with invasive bladder cancer (not statistically significant). We also observed increased expression in Hdac4, -7, and -9 in commonly used BC mouse models. Here, we identify suitable preclinical model systems for the study of HDACs, and show increased expression of Class IIa HDACs, specifically HDAC4 and HDAC9, in basal BC cell lines and in invasive clinical specimens. These results suggest this class of HDACs may be best suited for targeted inhibition in patients with basal BC.

HDAC5 Expression in Urothelial Carcinoma Cell Lines Inhibits Long-Term Proliferation but Can Promote Epithelial-to-Mesenchymal Transition

Class I histone deacetylases (HDACs) generally promote cell proliferation and tumorigenesis, whereas class IIA HDACs like HDAC4 and HDAC5 may promote or impede cancer development in a tissue-dependent manner. In urothelial carcinoma (UC), HDAC5 is often downregulated. Accordingly, HDAC5 was weakly expressed in UC cell lines suggesting a possible tumor-suppressive function. We therefore characterized the effects of stable HDAC5 expression in four UC cell lines (RT112, VM-Cub-1, SW1710 and UM-UC-3) with different phenotypes reflecting the heterogeneity of UC, by assessing proliferation, clonogenicity and migration ability. Further, we detailed changes in the proteome and transcriptome by immunoblotting, mass spectrometry and RNA sequencing analysis. We observed that HDAC5 overexpression in general decreased cell proliferation, but in one cell line (VM-Cub-1) induced a dramatic change from an epitheloid to a mesenchymal phenotype, i.e., epithelial-mesenchymal transition (EMT). These phenotypical changes were confirmed by comprehensive proteomics and transcriptomics analyses. In contrast to HDAC5, overexpression of HDAC4 exerted only weak effects on cell proliferation and phenotypes. We conclude that overexpression of HDAC5 may generally decrease proliferation in UC, but, intriguingly, may induce EMT on its own in certain circumstances.