Promoter hypermethylation in tumour suppressor genes and response to interleukin-2 treatment in bladder cancer: a pilot study

Targeting epigenetic regulatory machinery to overcome cancer therapy resistance

Drug resistance, either intrinsic or acquired, represents a major hurdle to achieving optimal therapeutic outcomes during cancer treatment. In addition to acquisition of resistance-conferring genetic mutations, accumulating evidence suggests an intimate involvement of the epigenetic machinery in this process as well. Recent studies have revealed that epigenetic reprogramming, such as altered expression or relocation of DNA/histone modulators accompanied with chromatin structure remodeling, can lead to transcriptional plasticity in tumor cells, thereby driving their transformation towards a persistent state. These "persisters" represent a pool of slow-growing cells that can either re-expand when treatment is discontinued or acquire permanent resistance. Targeting epigenetic reprogramming or plasticity represents a new strategy to prevent the emergence of drug-refractory populations and to enable more consistent clinical responses. With the growing numbers of drugs or drug candidates developed to target epigenetic regulators, more and more epigenetic therapies are under preclinical evaluation, early clinical trials or approved by FDA as single agent or in combination with existing antitumor drugs. In this review, we highlight latest discoveries in the mechanistic understanding of epigenetically-induced drug resistance. In parallel, we discuss the potential of combining epigenetic drugs with existing anticancer regimens as a promising strategy for overcoming cancer drug resistance.

Occurrence of Interleukin-2 (330 G/T) Promoter Polymorphism in ARV associated hepatotoxicity

BACKGROUND

IL-2 cytokine is involved in HIV replication and is also known to cause hepatic injury. Polymorphisms in the IL-2 gene are associated with altered interleukin-2 production.

METHODS

Hence, we assessed the prevalence of IL-2-303G/T polymorphism in 165 HIV patients (34 with and 131without hepatotoxicity) and 155 healthy controls using the PCR-RFLP method.

RESULTS

In patients with hepatotoxicity, IL-2-303GT, -303GT+TT genotypes were less prevalent as compared to without hepatotoxicity and healthy controls (29.4% vs. 42.7%, 58.8% vs. 69.5%; 29.4% vs. 40.6%, 58.8% vs. 66.5%, respectively). In patients with hepatotoxicity using tobacco and alcohol, IL-2-303GT,-303TT genotypes were distributed higher as compared to non-users (42.9% vs. 25.9%, OR=8.52, 42.9% vs. 25.9%, OR=9.09, and 28.6% vs. 29.6%, OR=1.63, 42.9% vs. 25.9%, OR=2.93), while IL-2-303TT genotype occurred more often in HIV patients consuming alcohol (34.1% vs. 23.0%). Nevirapine users with hepatotoxicity overrepresented the IL-2-303GT,-303TT genotypes as compared to efavirenz (34.8% vs. 18.2%, OR=4.64, 34.8% vs. 18.2%, OR=3.88). Among nevirapine users, IL-2-303GT genotype was associated with susceptibility to the acquisition of hepatotoxicity with borderline significance (OR=4.24, P=0.06). HIV patients using nevirapine majorly represented the IL-2-303TT genotype (26.9% vs. 25.0%, OR=2.35) while HIV patients with nevirapine + alcohol usage presented the IL-2 -330TT genotype at a higher frequency (34.2%% vs. 23.5%, OR=1.51). In patients with hepatotoxicity using nevirapine + alcohol, the genotype IL-2 - 330TT was predominant (60.0% vs. 27.8%, OR=3.16).

CONCLUSION

Thus, IL-2-303G/T polymorphism did not confer the susceptibility to ARV associated hepatotoxicity. However, IL-2-303G/T polymorphism with nevirapine usage may facilitate the risk for acquisition of ARV associated hepatotoxicity.

Epigenetic mechanisms as a new approach in cancer treatment: An updated review

Epigenetic, along with genetic mechanisms, is essential for natural evolution and maintenance of specific patterns of gene expression in mammalians. Global epigenetic variation is inherited somatically and unlike genetic variation, it is dynamic and reversible. They are somatically associated with known genetic variations. Recent studies indicate the broad role of epigenetic mechanisms in the initiation and development of cancers, that they are including DNA methylation, histone modifications, nucleosomes changes, non-coding RNAs. The reversible nature of epigenetic changes has led to the emergence of novel epigenetic therapeutic approaches, so that several types of these medications have been approved by the FDA so far. In this review, we discuss the concept of epigenetic changes in diseases, especially cancers, the role of these changes in the onset and progression of cancers and the potential of using this knowledge in designing novel therapeutic strategies.

The prognostic role of epigenetic dysregulation in bladder cancer: A systematic review

BACKGROUND

Despite adequate treatment and follow-up, around one fifth of patients with localized bladder cancer will present with disease progression. Adequate prognostic biomarkers are lacking to define patients who are at risk. Mutations in chromatin remodeling genes are more frequently found in bladder cancer than in any other solid tumor. However, the prognostic relevance of epigenetic dysregulation has not been established and may offer an opportunity for biomarker discovery.

METHODS

Looking for prognostic epigenetic factors, we performed a comprehensive PubMed search using keywords such as "bladder cancer", "chromatin remodeling", "gene methylation" and "epigenetics". We only included studies reporting on the association of epigenetic markers with prognostic outcomes such as recurrence, progression or survival.

RESULTS

Of 1113 results, 87 studies met the inclusion criteria, which represented a total of 85 epigenetic markers with potential prognostic relevance. No prospective studies were identified. Seventy-three percent (64/87) of the studies involved mixed cohorts of muscle invasive and non-muscle invasive bladder cancer. Promoter methylation of genes with putative prognostic value affected cellular processes such as cell cycle, apoptosis, cell-adhesion or migration, as well as critical pathways such as MAP-kinase or Wnt. Alteration of chromatin regulatory elements suggest a prognostic relevance alterations leading to a predominantly silenced chromatin state.

CONCLUSIONS

The prognostic impact of epigenetic alterations in bladder cancer is still unclear. Prospective evaluation of methylation marks and chromatin remodeling gene alterations using consistent methods and criteria is warranted.

DAPK Promoter Methylation and Bladder Cancer Risk: A Systematic Review and Meta-Analysis

BACKGROUND

Methylation of tumor suppressor gene promoter leads to transcription inactivation and is involved in tumorigenesis. Several studies demonstrate a potential association between the Death-Associated Protein Kinase (DAPK) gene promoter methylation and bladder cancer risk, tumor stage and histological grade. Due to inconsistent results of these studies, we performed this meta-analysis to ascertain the association.

METHODS

Studies were retrieved from the PubMed, Embase, Web of Science and the Cochrane Library databases. Study selection and data extraction were executed by two reviewers independently. Meta-analysis was performed using Stata 13.0 and Review Manager 5.3 software.

RESULTS

A total of 21 articles involving 15 case control and 8 case series studies were included in this meta-analysis. DAPK promoter methylation was associated with bladder cancer risk (OR: 5.81; 95%CI = 3.83-8.82, P<0.00001). The frequency of DAPK promoter methylation was equal in bladder cancer tissue and paired adjacent normal tissue (OR: 0.87; 95%CI = 0.31-2.48, P = 0.794). Furthermore, DAPK promoter methylation was associated with higher histological grade (OR: 1.52; 95%CI = 1.10-2.09, P = 0.011) but not associated with tumor stage (OR: 1.12; 95%CI = 0.67-1.87, P = 0.668).

CONCLUSIONS

The result suggests that DAPK promoter methylation is significantly increased in bladder cancer patients compared to normal controls. DAPK promoter methylation could serve as a biomarker for bladder cancer detection and management.

Association between two interleukin-2 gene polymorphisms and cancer susceptibility: a meta-analysis

Background

Several epidemiological studies have illustrated that polymorphisms in interleukin-2 (IL-2) were associated with diverse cancer types. However, recently published statistics were inconsistent and inconclusive. Therefore, the current meta-analysis was performed to elaborate the effects of IL-2 polymorphisms (rs2069762 and rs2069763) on cancer susceptibility.

Material and methods

A total of 5,601 cancer cases and 7,809 controls from 21 published case–control studies were enrolled in our meta-analysis. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the association between IL-2 polymorphisms and cancer susceptibility.

Results

Our study demonstrated an increased susceptibility to cancer in rs2069762 (G vs T: OR =1.268, 95% CI =1.113–1.445; GG vs TT: OR =1.801, 95% CI =1.289–2.516; GT vs TT: OR =1.250, 95% CI =1.061–1.473; GG + GT vs TT: OR =1.329, 95% CI =1.118–1.579; GG vs GT + TT: OR =1.536, 95% CI =1.162–2.030). In the subgroup analysis, increased susceptibility to cancer was identified in the hospital-based group and P_HWE<0.05 (P-value of the Hardy–Weinberg equilibrium [HWE]) group. In addition, a positive association with cancer susceptibility was observed among both Chinese and non-Chinese. However, no relationship was detected between the rs2069763 polymorphism of IL-2 and cancer susceptibility.

Conclusion

To conclude, rs2069762 polymorphism of IL-2 contributed to an increased susceptibility to cancer, whereas no association was identified between rs2069763 polymorphism and cancer susceptibility. Further detailed studies are warranted to confirm our findings.

Epigenetic modifications as therapeutic targets

Epigenetic modifications work in concert with genetic mechanisms to regulate transcriptional activity in normal tissues and are often dysregulated in disease. Although they are somatically heritable, modifications of DNA and histones are also reversible, making them good targets for therapeutic intervention. Epigenetic changes often precede disease pathology, making them valuable diagnostic indicators for disease risk or prognostic indicators for disease progression. Several inhibitors of histone deacetylation or DNA methylation are approved for hematological malignancies by the US Food and Drug Administration and have been in clinical use for several years. More recently, histone methylation and microRNA expression have gained attention as potential therapeutic targets. The presence of multiple epigenetic aberrations within malignant tissue and the abilities of cells to develop resistance suggest that epigenetic therapies are most beneficial when combined with other anticancer strategies, such as signal transduction inhibitors or cytotoxic treatments. A key challenge for future epigenetic therapies will be to develop inhibitors with specificity to particular regions of chromosomes, thereby potentially reducing side effects.

Association of IL-2 polymorphisms and IL-2 serum levels with susceptibility to HBV-related hepatocellular carcinoma in a Chinese Zhuang population

BACKGROUND AND OBJECTIVE

Interleukin-2 (IL-2) is an immunoregulatory cytokine produced by T cells and plays an important role in antitumor immunity. Variations in the DNA sequence of the IL-2 gene may lead to altered cytokine production and/or activity, and thus modulate an individual's susceptibility to hepatitis B virus-related hepatocellular carcinoma (HBV-related HCC). To test this hypothesis, we investigated whether IL-2 gene polymorphisms and its serum levels are associated with HBV-related HCC in a Chinese population.

METHODS

The +114T/G and -384T/G polymorphisms in the IL-2 gene were examined in 115 cases of chronic hepatitis B (CHB), 67 cases of HBV-related liver cirrhosis (LC), 107 cases of HBV-related HCC, and 105 healthy controls by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing. The serum IL-2 levels were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

We found that there were significant differences in the genotype and allele frequencies of the IL-2 gene +114T/G polymorphism between the HBV-related HCC patients and the healthy controls. The +114 TG and GG genotypes were associated with a significant increased HCC risk as compared with the TT genotype (OR=1.988, 95% CI, 1.034-3.480, P=0.009 for TG genotype, and OR=1.975, 95% CI, 1.012-3.341, P=0.013 for GG genotype, respectively). The +114 G allele was correlated with a significant increased HCC risk as compared with the T allele (OR=1.423, 95% CI, 1.023-1.975, P=0.031). In addition, we found significant decreased serum IL-2 in HBV-related HCC patients (288.6±177.1ng/L) compared with healthy controls (238.2±136.7ng/L) (t=2.32, P=0.021). Genotypes carrying the +114 G variant allele were associated with decreased serum IL-2 levels compared with the homozygous wild-type genotype in HBV-related HCC patients.

CONCLUSION

The results suggested that the IL-2 +114T/G polymorphism may contribute to increased HBV-related HCC risk through regulating the serum IL-2 levels. Further large and well-designed studies in diverse ethnic populations are needed to confirm our results.

Serum secreted frizzled-related protein 5 levels differentially decrease in patients with hepatitis B virus-associated chronic infection and hepatocellular carcinoma

The aim of this study was to investigate the characteristics of serum secreted frizzled-related protein 5 (SFRP5), an inhibitor of Wnt signaling, in hepatitis B virus (HBV)-associated infections and hepatocellular carcinoma (HCC) patients. Serum SFRP5 levels were detected in 147 patients with HBV-associated chronic infection or HCC. Compared with the non-HBV-infected and non-HCC group, the HBV-associated chronic infection and HCC groups exhibited decreased serum SFRP5 levels. A significant inverse correlation between serum SFRP5 levels and HBV DNA levels was identified in the HBV-associated chronic infection and HCC groups. Furthermore, SFRP5 levels differentially decreased in patients with HBV-associated diseases, in a manner which was dependent on liver disease status. Compared with patients exhibiting HBV-associated chronic infection, patients with HCC were found to exhibit lower serum SFRP5 levels. The results of the present study indicated that patients with HBV-associated liver infection and HCC exhibited significantly deceased serum SFRP5 levels, which were found to negatively correlate with HBV DNA levels. Serum SFRP5 levels may present a biomarker for the severity of HBV-associated liver infection, and the risk of HCC initiation and progression.

Comparative study and meta-analysis of meta-analysis studies for the correlation of genomic markers with early cancer detection

A large number of common disorders, including cancer, have complex genetic traits, with multiple genetic and environmental components contributing to susceptibility. A literature search revealed that even among several meta-analyses, there were ambiguous results and conclusions. In the current study, we conducted a thorough meta-analysis gathering the published meta-analysis studies previously reported to correlate any random effect or predictive value of genome variations in certain genes for various types of cancer. The overall analysis was initially aimed to result in associations (1) among genes which when mutated lead to different types of cancer (e.g. common metabolic pathways) and (2) between groups of genes and types of cancer. We have meta-analysed 150 meta-analysis articles which included 4,474 studies, 2,452,510 cases and 3,091,626 controls (5,544,136 individuals in total) including various racial groups and other population groups (native Americans, Latinos, Aborigines, etc.). Our results were not only consistent with previously published literature but also depicted novel correlations of genes with new cancer types. Our analysis revealed a total of 17 gene-disease pairs that are affected and generated gene/disease clusters, many of which proved to be independent of the criteria used, which suggests that these clusters are biologically meaningful.

Oncolytic viruses in the treatment of bladder cancer

Bladder carcinoma is the second most common malignancy of the urinary tract. Up to 85% of patients with bladder cancer are diagnosed with a tumor that is limited to the bladder mucosa (Ta, T1, and CIS). These stages are commonly termed as non-muscle-invasive bladder cancer (NMIBC). Although the treatment of NMIBC has greatly improved in recent years, there is a need for additional therapies when patients fail bacillus Calmette-Guérin (BCG) and chemotherapeutic agents. We propose that bladder cancer may be an ideal target for oncolytic viruses engineered to selectively replicate in and lyse tumor cells leaving normal cells unharmed. In support of this hypothesis, here we review current treatment strategies for bladder cancer and their shortcomings, as well as recent advancements in oncolytic viral therapy demonstrating encouraging safety profiles and antitumor activity.

Hypermethylation in bladder cancer: biological pathways and translational applications

A compelling body of evidences sustains the importance of epigenetic mechanisms in the development and progression of cancer. Assessing the epigenetic component of bladder tumors is strongly improving our understanding of their biology and clinical behavior. In terms of DNA methylation, cancer cells show genome-wide hypomethylation and site-specific CpG island promoter hypermethylation. In the context of other epigenetic alterations, this review will focus on the hypermethylation of CpG islands in promoter regions, as the most widely described epigenetic modification in bladder cancer. CpG islands hypermethylation is believed to be critical in the transcriptional silencing and regulation of tumor suppressor and crucial cancer genes involved in the major molecular pathways controlling bladder cancer development and progression. In particular, several biological pathways of frequently methylated genes include cell cycle, DNA repair, apoptosis, and invasion, among others. Furthermore, translational aspects of bladder cancer methylomes described to date will be discussed towards their potential application as bladder cancer biomarkers. Several tissue methylation signatures and individual candidates have been evidenced, that could potentially stratify tumors histopathologically, and discriminate patients in terms of their clinical outcome. Tumor methylation profiles could also be detected in urinary specimens showing a promising role as non-invasive markers for cancer diagnosis towards an early detection and potentially for the surveillance of bladder cancer patients in a near future. However, the epigenomic exploration of bladder cancer has only just begun. Genome-scale DNA methylation profiling studies will further highlight the relevance of the epigenetic component to gain knowledge of bladder cancer biology and identify those profiles and candidates better correlating with clinical behavior.

Evaluation of innate immune signaling pathways in transformed cells

Oncolytic viruses, the use of viruses to treat cancer, is emerging as a new option for cancer therapy. Oncolytic viruses, of both DNA and RNA origin, exhibit the ability to preferentially replicate in and kill cancer cells plausibly due to defects in innate immune signaling or translation regulation that are acquired during cellular transformation. Here, we review concepts and assays that describe how to analyze signaling pathways that govern the regulation of Type I IFN production as well as the induction of interferon-stimulated antiviral genes, events that are critical for mounting an effective antiviral response. The following procedures can be used to assess whether innate immune pathways that control antiviral host defense are defective in tumor cells - mechanisms that may help to explain viral oncolysis.

DNA methylation as a universal biomarker

Cell-free circulating DNA carries not only tumor-specific changes in its sequence but also distinctive epigenetic marks, namely DNA methylation, in certain GC-rich fragments. These fragments are usually located within the promoters and first exons of many genes, comprising CpG islands. Analysis of DNA methylation using cell-free circulating DNA can facilitate development of very accurate biomarkers for detection, diagnosis, prediction of response to therapy and prognosis of outcomes. Recent data suggest that benign and inflammatory diseases have very specific methylation patterns within cell-free circulating DNA, which are different from the pattern of a malignant tumor of the same organ. In addition, specific methylation patterns have been detected for cancers of different organs, so a differential diagnosis of site-specific cancer appears feasible. Currently, cancer-related applications dominate the field, although methylation-based biomarkers may also be possible for other diseases, including neurodegenerative and psychiatric disorders.

Analysis of external and internal interlibrary loan requests: aid in collection management

The analysis of 60,779 external interlibrary loan requests for copies of periodical articles from the collection of Erasmus University Medical Library in 1988 is described. The study was used for planning the length of backruns to be retained due to space limitations that forced the disposal of older volumes. More than 50% of requests were for the most recent two-year period, and 90% of requests could be filled with a twenty-year run of periodicals. In 1989, 4,157 internal requests were received for periodicals not owned; these were analyzed to determine those most commonly requested. Prior to subscribing, new titles were reviewed as to price, bibliometric indicators, number of requests, length of backfile, and the number of requesting departments. The Library Advisory Board decides on cancellation or purchase of periodicals; the elements considered are described.