Does Wnt/β-catenin pathway contribute to the stability of DNMT1 expression in urological cancer cell lines?

The role of E3 ubiquitin ligases and deubiquitinases in bladder cancer development and immunotherapy

Bladder cancer is one of the common malignant urothelial tumors. Post-translational modification (PTMs), including ubiquitination, acetylation, methylation, and phosphorylation, have been revealed to participate in bladder cancer initiation and progression. Ubiquitination is the common PTM, which is conducted by E1 ubiquitin-activating enzyme, E2 ubiquitin-conjugating enzyme and E3 ubiquitin-protein ligase. E3 ubiquitin ligases play a key role in bladder oncogenesis and progression and drug resistance in bladder cancer. Therefore, in this review, we summarize current knowledge regarding the functions of E3 ubiquitin ligases in bladder cancer development. Moreover, we provide the evidence of E3 ubiquitin ligases in regulation of immunotherapy in bladder cancer. Furthermore, we mention the multiple compounds that target E3 ubiquitin ligases to improve the therapy efficacy of bladder cancer. We hope our review can stimulate researchers and clinicians to investigate whether and how targeting E3 ubiquitin ligases acts a novel strategy for bladder cancer therapy.

The USP7 protein interaction network and its roles in tumorigenesis

Ubiquitin-specific protease (USP7), also known as Herpesvirus-associated ubiquitin-specific protease (HAUSP), is a deubiquitinase. There has been significant recent attention on USP7 following the discovery that USP7 is a key regulator of the p53-MDM2 pathway. The USP7 protein is 130 kDa in size and has multiple domains which bind to a diverse set of proteins. These interactions mediate key developmental and homeostatic processes including the cell cycle, immune response, and modulation of transcription factor and epigenetic regulator activity and localization. USP7 also promotes carcinogenesis through aberrant activation of the Wnt signalling pathway and stabilization of HIF-1α. These findings have shown that USP7 may induce tumour progression and be a therapeutic target. Together with interest in developing USP7 as a target, several studies have defined new protein interactions and the regulatory networks within which USP7 functions. In this review, we focus on the protein interactions of USP7 that are most important for its cancer-associated roles.

Proteome Analysis of USP7 Substrates Revealed Its Role in Melanoma Through PI3K/Akt/FOXO and AMPK Pathways

The ubiquitin-specific protease 7 (USP7), as a deubiquitinating enzyme, plays an important role in tumor progression by various mechanisms and serves as a potential therapeutic target. However, the functional role of USP7 in melanoma remains elusive. Here, we found that USP7 is overexpressed in human melanoma by tissue microarray. We performed TMT-based quantitative proteomic analysis to evaluate the A375 human melanoma cells treated with siRNA of USP7. Our data revealed specific proteins as well as multiple pathways and processes that are impacted by USP7. We found that the phosphatidylinositol-3-kinases/Akt (PI3K-Akt), forkhead box O (FOXO), and AMP-activated protein kinase (AMPK) signaling pathways may be closely related to USP7 expression in melanoma. Moreover, knockdown of USP7 in A375 cells, particularly USP7 knockout using CRISPR-Cas9, verified that USP7 regulates cell proliferation in vivo and in vitro. The results showed that inhibition of USP7 increases expression of the AMPK beta (PRKAB1), caspase 7(CASP7), and protein phosphatase 2 subunit B R3 isoform (PPP2R3A), while attenuating expression of C subunit of vacuolar ATPase (ATP6V0C), and peroxisomal biogenesis factor 11 beta (PEX11B). In summary, these findings reveal an important role of USP7 in regulating melanoma progression via PI3K/Akt/FOXO and AMPK signaling pathways and implicate USP7 as an attractive anticancer target for melanoma.

Contrast effects of autophagy in the treatment of bladder cancer

Bladder cancer is a disease that negatively affects patients' quality of life, but treatment options have remained unchanged for a long time. Although promising results have been achieved with current bladder cancer treatments, cancer recurrence, progression, and therapy resistance are the most severe problems preventing the efficiency of bladder cancer treatments. Autophagy refers to an evolutionarily conserved catabolic process in which proteins, damaged organelles, and cytoplasmic components are degraded by lysosomal enzymes. Autophagy regulates the therapeutic response to the chemotherapy drugs, thus determining the effect of therapy on cancer cells. Autophagy is a stress-induced cell survival mechanism and its excessive stimulation can cause resistance of tumor cells to therapeutic agents. Depending on the conditions, an increase in autophagy may cause treatment resistance or autophagic cell death, and it is related to important anti-cancer mechanisms, such as apoptosis. Therefore, understanding the roles of autophagy under different conditions is important for designing effective anti-cancer agents. The dual role of autophagy in cancer has attracted considerable attention in respect of bladder cancer treatment. In this review, we summarize the basic characteristics of autophagy, including its mechanisms, regulation, and functions, and we present examples from current studies concerning the dual role of autophagy in bladder cancer progression and therapy.

Oncogenic roles of the cholesterol metabolite 25-hydroxycholesterol in bladder cancer

Oxysterols, such as 24S-hydroxycholesterol and 25-hydroxycholesterol are oxidation products of cholesterol generated by enzymatic reactions. The pathological effects of oxysterols have been described in multiple types of cancer, including cancers of the skin, lung, colon, breast and bile ducts. The molecular mechanisms underlying oxysterol-induced cancer initiation and progression have yet to be completely elucidated, and to the best of our knowledge, no prior data on the role of 24S-hydroxycholesterol and 25-hydroxycholesterol in bladder cancer exists. The results of the present study demonstrated that 25-hydroxycholesterol is increased in bladder cancer tissues, and that it promotes proliferation and the epithelial-to-mesenchymal transition in human T24 and RT4 bladder cancer cells. It was also observed that 25-hydroxycholesterol promotes Adriamycin resistance in T24 and RT4 cells, and that high levels of 25-hydroxycholesterol in bladder cancer are associated with a poor outcome. Therefore, 25-hydroxycholesterol, a primary metabolite of cholesterol, may serve an important role in the progression of bladder cancer.

The effect of heat shock protein 90 inhibitors on histone 4 lysine 20 methylation in bladder cancer

Heat shock protein 90 (HSP90), an ATP-dependent molecular chaperone required for the stability and function of numerous oncogenic signaling, is one of the hallmarks of cancer. Recent years, the studies showed that HSP90 plays a pivotal role in epigenetic pathways. Epigenetic regulation plays an important role in the etiology of bladder cancer. The aim of the present study was to investigate the effect of HSP90 proteins on DNA methylation and the levels of inactivated histone methylation markers in bladder cancers. The cytotoxic effect of geldanamycin (GA), a HSP90-specific inhibitor, in human bladder cancer cell line, T24, was studied by using WST1 (both time and dose-dependent), qPCR for the expression aberration of target genes DNMT1 and WIF-1 and western blot for the protein levels of DNMT1, Histone H4, Histone 4 lysine monomethylation (H4K20me1), Histone 4 lysine trimethylation (H4K20me3), Akt1, pAkt1 (S473) and Lysine methyltransferase 5C (KMT5C). High-dose GA treatment decreased cell proliferation. After the GA treatment, DNMT1 decreased at both transcriptional and translational levels due to Akt1 and pAkt1 (S473) inhibition. Following the GA-induced decrease in DNMT1, re-expression of WIF-1 gene was found at mRNA. In addition, the GA treatment resulted in dose- and time-dependent upregulation/downregulation of histone post-translational modifications (H4K20me1 and H4K20me3) and the KMT5C enzyme responsible for these modifications. There was no significant change in the H4 protein level. These findings may offer a new approach for the determination of the molecular effect of HSP90 on epigenetic regulation and the identification of new molecular targets (HSP90 client proteins) for bladder cancer treatment.

Emerging insights into HAUSP (USP7) in physiology, cancer and other diseases

Herpesvirus-associated ubiquitin-specific protease (HAUSP) is a USP family deubiquitinase. HAUSP is a protein of immense biological importance as it is involved in several cellular processes, including host-virus interactions, oncogenesis and tumor suppression, DNA damage and repair processes, DNA dynamics and epigenetic modulations, regulation of gene expression and protein function, spatio-temporal distribution, and immune functions. Since its discovery in the late 1990s as a protein interacting with a herpes virus regulatory protein, extensive studies have assessed its complex roles in p53-MDM2-related networks, identified numerous additional interacting partners, and elucidated the different roles of HAUSP in the context of cancer, development, and metabolic and neurological pathologies. Recent analyses have provided new insights into its biochemical and functional dynamics. In this review, we provide a comprehensive account of our current knowledge about emerging insights into HAUSP in physiology and diseases, which shed light on fundamental biological questions and promise to provide a potential target for therapeutic intervention.

Improved understandings of a molecular-tag-removing enzyme could lead to the development of therapies for many diseases. Dr. Mrinal K Ghosh of the Council of Scientific and Industrial Research-Indian Institute of Chemical Biology (CSIR-IICB) and colleagues reviewed 20 years of research on herpesvirus-associated ubiquitin-specific protease (HAUSP), involved in a wide range of cellular processes through its role in removing the ubiquitin from molecules, thus signaling their fate. It was first discovered in/as a herpes virus infected cells, ultimately enhancing infection. It was later found to have a wide range of functions depending on the molecules it interacts with under normal physiological and disease conditions. Targeting HAUSP with drugs shows promise for suppressing prostate, lung, colon, breast, blood, and other cancers. It could also impact treatment of neurological conditions such as Huntington’s disease, and metabolic disorders, such as diabetes.

Microrna-217 modulates human skin fibroblast senescence by directly targeting DNA methyltransferase 1

DNA methyltransferase 1 (DNMT1) is a major epigenetic regulator associated with many biological processes. However, the roles and mechanisms of DNMT1 in skin aging are incompletely understood. Here we explored the role of DNMT1 in human skin fibroblasts senescence and its related regulatory mechanisms. DNMT1 expression decreased in passage-aged fibroblasts and DNMT1 silencing in young fibroblasts induced the senescence phenotype. MiR-217 is predicted to target DNMT1 mRNA and miR-217 expression increased in passage-aged fibroblasts. MiR-217 directly targeted the 3′-untranslated region (3′-UTR) of DNMT1 in HEK 293T cells and inhibited DNMT1 expression in fibroblasts. MiR-217 overexpression induced a senescence phenotype in young fibroblasts, and miR-217 downregulation in old HSFs partially reversed the senescence phenotype. However, these effects could be significantly rescued by regulating DNMT1 expression in fibroblasts. After regulating miR-217 levels, we analyzed changes in the promoter methylation levels of 24 senescent-associated genes, finding that 6 genes were significantly altered, and verified p16 and phosphorylated retinoblastoma (pRb) protein levels. Finally, an inverse correlation between DNMT1 and miR-217 expression was observed in skin tissues and different-aged fibroblasts. Together, these findings revealed that miR-217 promotes fibroblasts senescence by suppressing DNMT1-mediated methylation of p16 and pRb by targeting the DNMT1 3′-UTR.

Expression profiles of CD11b, galectin-1, beclin-1, and caspase-3 in nasal polyposis

Background/aim: Nasal polyposis is a chronic inflammatory disease affecting the paranasal sinuses and nasal mucosae. It is thought that genetic and molecular mechanisms in inflammatory and apoptotic pathways are the main factors in the etiopathogenesis of nasal polyposis. The aim of this study was to investigate the expression patterns of CD11b, galectin-1, beclin-1, and caspase-3 in nasal polyps.Materials and methods: The mRNA expression levels of CD11b, galectin-1, beclin-1, and caspase-3 protein and western blot analysis of caspase-3 protein were evaluated in inferior turbinate mucosae and nasal polyp tissues.Results: CD11b expression was markedly higher in nasal polyp tissues when compared to turbinate mucosae (5.5 times higher, P < 0.05). Expression of galectin-1 was not statistically higher in nasal polyp tissues when compared to the controls. Beclin-1 expression in nasal polyp tissues was lower than in controls (17 times lower, P < 0.05). Caspase-3 expression was significantly lower in nasal polyp tissues than in controls (5.5 times lower, P < 0.05).Conclusion: Inflammation, apoptosis, and hyperproliferation are the major cellular processes in nasal polyposis and these proteins may take part and play some important roles in formation of this disease and the targeting of new treatment protocols.

Concerted changes in transcriptional regulation of genes involved in DNA methylation, demethylation, and folate-mediated one-carbon metabolism pathways in the NCI-60 cancer cell line panel in response to cancer drug treatment

BACKGROUND

Aberrant patterns of DNA methylation are abundant in cancer, and epigenetic pathways are increasingly being targeted in cancer drug treatment. Genetic components of the folate-mediated one-carbon metabolism pathway can affect DNA methylation and other vital cell functions, including DNA synthesis, amino acid biosynthesis, and cell growth.

RESULTS

We used a bioinformatics tool, the Transcriptional Pharmacology Workbench, to analyze temporal changes in gene expression among epigenetic regulators of DNA methylation and demethylation, and one-carbon metabolism genes in response to cancer drug treatment. We analyzed gene expression information from the NCI-60 cancer cell line panel after treatment with five antitumor agents, 5-azacytidine, doxorubicin, vorinostat, paclitaxel, and cisplatin. Each antitumor agent elicited concerted changes in gene expression of multiple pathway components across the cell lines. Expression changes of FOLR2, SMUG1, GART, GADD45A, MBD1, MTR, MTHFD1, and CTH were significantly correlated with chemosensitivity to some of the agents. Among many genes with concerted expression response to individual antitumor agents were genes encoding DNA methyltransferases DNMT1, DNMT3A, and DNMT3B, epigenetic and DNA repair factors MGMT, GADD45A, and MBD1, and one-carbon metabolism pathway members MTHFD1, TYMS, DHFR, MTR, MAT2A, SLC19A1, ATIC, and GART.

CONCLUSIONS

These transcriptional changes are likely to influence vital cellular functions of DNA methylation and demethylation, cellular growth, DNA biosynthesis, and DNA repair, and some of them may contribute to cytotoxic and apoptotic action of the drugs. This concerted molecular response was observed in a time-dependent manner, which may provide future guidelines for temporal selection of genetic drug targets for combination drug therapy treatment regimens.