P16 Promoter Research Articles

Differential responses of healthy and chronic obstructive pulmonary diseased human bronchial epithelial cells repeatedly exposed to air pollution-derived PM4

While the knowledge of the underlying mechanisms by which air pollution-derived particulate matter (PM) exerts its harmful health effects is still incomplete, detailed in vitro studies are highly needed. With the aim of getting closer to the human in vivo conditions and better integrating a number of factors related to pre-existing chronic pulmonary inflammatory, we sought to develop primary cultures of normal human bronchial epithelial (NHBE) cells and chronic obstructive pulmonary disease (COPD)-diseased human bronchial epithelial (DHBE) cells, grown at the air-liquid interface. Pan-cytokeratin and MUC5AC immunostaining confirmed the specific cell-types of both these healthy and diseased cell models and showed they are closed to human bronchial epithelia. Thereafter, healthy and diseased cells were repeatedly exposed to air pollution-derived PM4 at the non-cytotoxic concentration of 5 μg/cm2. The differences between the oxidative and inflammatory states in non-exposed NHBE and COPD-DHBE cells indicated that diseased cells conserved their specific physiopathological characteristics. Increases in both oxidative damage and cytokine secretion were reported in repeatedly exposed NHBE cells and particularly in COPD-DHBE cells. Diseased cells repeatedly exposed had lower capacities to metabolize the organic chemicals-coated onto the air-pollution-derived PM4, such as benzo[a]pyrene (B[a]P), but showed higher sensibility to the formation of OH-B[a]P DNA adducts, because their diseased state possibly affected their defenses. Differential profiles of epigenetic hallmarks (i.e., global DNA hypomethylation, P16 promoter hypermethylation, telomere length shortening, telomerase activation, and histone H3 modifications) occurred in repeatedly exposed NHBE and particularly in COPD-DHBE cells. Taken together, these results closely supported the highest responsiveness of COPD-DHBE cells to a repeated exposure to air pollution-derived PM4. The use of these innovative in vitro exposure systems such as NHBE and COPD-DHBE cells could therefore be consider as a very useful and powerful promising tool in the field of the respiratory toxicology, taking into account sensitive individuals.

Abstract 999: P16 DNA methylation inactivates transcription of IncRNA ANRIL

Abstract The exonic ANRIL (P15AS) is a 3.8-kb lncRNA transcribed from the antisense strand of the P14 promoter and flanking regions. Recently, we have constructed a P16 promoter DNA methyltransferase (P16-Dnmt) using the pTRIPZ vector that can specifically methylate human P16 CpG islands and found that P16 methylation directly leads to gene transcription silence [Cui et al. Genome Biology 2015, 16:252]. However, whether ANRIL transcription is affected by P16 DNA methylation has not previously been reported. In the present study, correlation between endogenous P16, P15, P14 mRNA and ANRIL levels in a panel of cell lines were determined using quantitative RT-PCR. Unexpectedly, the results showed that ANRIL transcriptional level was positively and significantly correlated with the P16 mRNA level (r = 0.774, P = 0.003), but not correlated with the P15 or P14 mRNA levels (r = 0.09 or 0.30, P = 0.78 or 0.35). These phenomena were confirmed using the public available transcriptome data in the Broad-Novartis Cancer Cell Line Encyclopedia (CCLE). Furthermore, transcription of both ANRIL and P16 mRNA were observed only in cancer cell lines in which the P16 alleles are unmethylated (Caski, SGC7901, BGC823, GES1, Siha and HeLa), but not in these cell lines in which the P16 alleles are fully methylated (Colo205, PC3, MHCC97H, RKO, SW480 and AGS). These suggest the possibility that methylation of the P16 promoter may inactivate transcription of ANRIL as well as P16. To study the possible causality between P16 DNA methylation and transcriptional silence of ANRIL, we employed P16-Dnmt to induce P16-specific DNA methylation in gastric cancer BGC823 cells, and found that transcription levels of both P16 and ANRIL were significantly decreased by the induced P16 DNA methylation (P<0.001 and 0.024, respectively). Besides, transcription level of P14 was also reduced (P = 0.043) while the P14 promoter CpG islands remained to be unmethylated. In contrast, P16 DNA demethylation induced by an artificial P16-specific transcription factor [Zhang et al. Human Gene Therapy 2012, 23:1071-81] re-activated transcription of both ANRIL and P16 in H1299 cells (P<0.001). The mechanism of inactivation of ANRIL expression by P16 DNA methylation is under investigation. In conclusion, transcription of ANRIL is regulated by P16 DNA methylation. Citation Format: Ying Gan, Baozhen Zhang, Chenghua Cui, Dajun Deng. P16 DNA methylation inactivates transcription of IncRNA ANRIL. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 999.

Lack of Correlation between Aberrant p16, RAR-β2, TIMP3, ERCC1, and BRCA1 Protein Expression and Promoter Methylation in Squamous Cell Carcinoma Accompanying Candida albicans-Induced Inflammation

Hyperplastic candidiasis is characterized by thickening of the mucosal epithelia with Candida albicans infection with occasional progression to squamous cell carcinoma (SCC). C. albicans is a critical factor in tumor development; however, the oncogenic mechanism is unclear. We have previously produced an animal model for hyperplastic candidiasis in the rat forestomach. In the present study, we investigate whether impaired DNA methylation and associated protein expression of tumor suppressor and DNA repair genes are involved in the SCC carcinogenesis process using this hyperplastic candidiasis model. Promoter methylation and protein expression were analyzed by methylation specific PCR and immunohistochemical staining, respectively, of 5 areas in the forestomachs of alloxan-induced diabetic rats with hyperplastic candidiasis: normal squamous epithelia, squamous hyperplasia, squamous hyperplasia adjacent to SCC, squamous hyperplasia transitioning to SCC, and SCC. We observed nuclear p16 overexpression despite increases in p16 gene promoter methylation during the carcinogenic process. TIMP3 and RAR-β2 promoter methylation progressed until the precancerous stage but disappeared upon malignant transformation. In comparison, TIMP3 protein expression was suppressed during carcinogenesis and RAR-β2 expression was attenuated in the cytoplasm but enhanced in nuclei. ERCC1 and BRCA1 promoters were not methylated at any stage; however, their protein expression disappeared beginning at hyperplasia and nuclear protein re-expression in SCC was observed only for ERCC1. These results suggest that aberrant p16, RAR-β2, TIMP3, ERCC1, and BRCA1 expression might occur that is inconsistent with the respective gene promoter methylation status, and that this overexpression might serve to promote the inflammatory carcinogenesis caused by C. albicans infection.

Methylation and mRNA expression levels of P15, death-associated protein kinase, and suppressor of cytokine signaling-1 genes in multiple myeloma.

The aim of this study was to investigate the methylation status and mRNA expression levels of P15, death-associated protein kinase (DAPK), and suppressor of cytokine signaling-1 (SOCS1) genes in multiple myeloma (MM). The bone marrow samples of 54 MM patients were collected and the methylation status of the P15, DAPK, and SOCS1 gene promoter regions was determined by methylation-specific polymerase chain reaction. Automated sequencing technology was used to sequence the amplified products in order to analyze the base methylation sites. mRNA expression levels were determined using real-time fluorescent quantitative polymerase chain reaction. Among the 54 MM patients, the positive methylation rates of the P15, DAPK, and SOCS1 genes were 27.78%, 18.52%, and 16.67%, respectively. The methylation results were confirmed by sequencing. The positive methylation rates of the P15, DAPK, and SOCS1 genes showed no correlation with patient gender, age, typing, staging, and grouping (P>0.05). There was no significant difference in the mRNA expression levels of the P15, DAPK, and SOCS1 genes between the MM patient group and the control group (P>0.05). Aberrant methylation of the P15, DAPK, and SOCS1 genes exists in MM, and these genes may play certain roles in pathogenesis of MM. There was no significant difference in mRNA expression levels between the methylated group and the non-methylated group, suggesting that these genes are regulated by other mechanisms during their transcription.

Clinicopathological significance of p15 promoter hypermethylation in multiple myeloma: a meta-analysis.

Published studies reported that loss of function of the p15INK4B gene is caused by hypermethylation; however, whether or not the inactivation is associated with the incidence and clinical significance of multiple myeloma (MM) remains unclear. In this study, we performed a meta-analysis to quantitatively determine the effects of p15 hypermethylation on the incidence of MM. The related research articles in English and Chinese languages were evaluated. The data were extracted and assessed independently. The pooled data were analyzed and odds ratios were calculated and summarized. Sixteen eligible studies were selected for final analysis. We demonstrated that p15 hypermethylation is significantly higher in MM than that in normal bone marrow, as well as monoclonal gammopathy of undetermined significance. However, aberrant p15 hypermethylation was not significantly higher in advanced MM than that in early-stage MM. The results of this study reveal that p15 hypermethylation is correlated with an increased risk in the progression of monoclonal gammopathy of undetermined significance to MM. p15 hypermethylation, which induces the loss of function of the p15 gene, plays a critical role in the early tumorigenesis of MM and serves as a reputable diagnostic marker and potential drug target.

P-006 Hypermethylation of APC, CDH13, MLH1, MGMT, P16 and RASSF1A promoter regions in patients with colorectal cancer

P-006 Hypermethylation of APC, CDH13, MLH1, MGMT, P16 and RASSF1A promoter regions in patients with colorectal cancer

Cigarette Smoking, BPDE-DNA Adducts, and Aberrant Promoter Methylations of Tumor Suppressor Genes (TSGs) in NSCLC from Chinese Population

ABSTRACTNon–small cell lung cancer (NSCLC) is related to the genetic and epigenetic factors. The goal of this study was to determine association of cigarette smoking and BPDE-DNA adducts with promoter methylations of several genes in NSCLC. Methylation of the promoters of p16, RARβ, DAPK, MGMT, and TIMP-3 genes of tumor tissues from 199 lung cancer patients was analyzed with methylation-specific PCR (MSP), and BPDE-DNA adduct level in lung cancer tissue was obtained by ELISA. Level of BPDE-DNA adduct increased significantly in males, aged people (over 60 years), and smokers; however, no significant difference was found while comparing the BPDE-DNA adduct levels among different tumor types, locations, and stages. Cigarette smoking was also associated with increased BPDE-DNA adducts level (OR = 2.43, p > .05) and increased methylation level in at least 1 gene (OR = 5.22, p < .01), both in dose–response manner. Similarly, cigarette smoking also significantly increase the risk of p16 or DAPK methylation (OR = 3.02, p < .05 for p16, and 3.66, p < .05 for DAPK). The highest risk of BPDE-DNA adducts was detected among individuals with cigarette smoking for more than 40 pack-years (OR = 4.21, p < .01). Furthermore, the present study did not show that BPDE-DNA adducts are significantly associated with abnormal TSGs methylations in NSCLC, including SCC and AdO, respectively. Conclusively, cigarette smoking is significantly associated with the increase of BPDE-DNA adduct level, promoter hypermethylation of p16 and DAPK genes, while BPDE-DNA adduct was not significantly related to abnormal promoter hypermethylation in TSGs, suggesting that BPDE-DNA adducts and TSGs methylations play independent roles in NSCLC.

Breast primary epithelial cells that escape p16-dependent stasis enter a telomere-driven crisis state.

Breast cancer is the most common malignant disease in women, but some basic questions remain in breast cancer biology. To answer these, several cell models were developed. Recently, the use of improved cell-culture conditions has enabled the development of a new primary cell model with certain luminal characteristics. This model is relevant because, after the introduction of a specific set of genetic elements, the transformed cells yielded tumors resembling human adenocarcinomas in mice. The use of improved cell-culture conditions supporting the growth of these breast primary epithelial cells was expected to delay or eliminate stress-induced senescence and lead to the propagation of normal cells. However, no studies have been carried out to investigate these points. Propagation of breast primary epithelial cells was performed in WIT medium on Primaria plates. Immunofluorescence, western blot and qRT-PCR were used to detect molecular markers, and to determine the integrity of DNA damage-response pathways. Promoter methylation of p16 INK4a was assessed by pyrosequencing. In order to obtain a dynamic picture of chromosome instability over time in culture, we applied FISH methodologies. To better link chromosome instability with excessive telomere attrition, we introduced the telomerase reverse transcriptase human gene using a lentiviral vector. We report here that breast primary epithelial cells propagated in vitro with WIT medium on Primaria plates express some luminal characteristics, but not a complete luminal lineage phenotype. They undergo a p16-dependent stress-induced senescence (stasis), and the cells that escape stasis finally enter a crisis state with rampant chromosome instability. Chromosome instability in these cells is driven by excessive telomere attrition, as distributions of chromosomes involved in aberrations correlate with the profiles of telomere signal-free ends. Importantly, ectopic expression of the human TERT gene rescued their chromosomal instability phenotype. Essentially, our data show that contrary to what was previously suggested, improved culture conditions to propagate in vitro mammary epithelial cells with some luminal characteristics do not prevent stress-induced senescence. This barrier is overcome by spontaneous methylation of the p16 INK4a promoter, allowing the proliferation of cells with telomere dysfunction and ensuing chromosome instability.Electronic supplementary materialThe online version of this article (doi:10.1186/s13058-015-0667-z) contains supplementary material, which is available to authorized users.

Antiproliferative Effect of Androgen Receptor Inhibition in Mesenchymal Stem-Like Triple-Negative Breast Cancer

Background/Aims: Androgen receptor (AR), a steroid hormone receptor, has recently emerged as prognostic and treatment-predictive marker in breast cancer. Previous studies have shown that AR is widely expressed in up to one-third of triple-negative breast cancer (TNBC). However, the role of AR in TNBC is still not fully understood, especially in mesenchymal stem-like (MSL) TNBC cells. Methods: MSL TNBC MDA-MB-231 and Hs578T breast cancer cells were exposed to various concentration of agonist 5-α-dihydrotestosterone (DHT) or nonsteroidal antagonist bicalutamide or untreated. The effects of AR on cell viability and apoptosis were determined by MTT assay, cell counting, flow cytometry analysis and protein expression of p53, p73, p21 and Cyclin D1 were analyzed by western blotting. The bindings of AR to p73 and p21 promoter were detected by ChIP assay. MDA-MB-231 cells were transplanted into nude mice and the tumor growth curves were determined and expression of AR, p73 and p21 were detected by Immunohistochemistry (IHC) staining after treatment of DHT or bicalutamide. Results: We demonstrate that AR agonist DHT induces MSL TNBC breast cancer cells proliferation and inhibits apoptosis in vitro. Similarly, activated AR significantly increases viability of MDA-MB-231 xenografts in vivo. On the contrary, AR antagonist, bicalutamide, causes apoptosis and exerts inhibitory effects on the growth of breast cancer. Moreover, DHT-dependent activation of AR involves regulation in the cell cycle related genes, including p73, p21 and Cyclin D1. Further investigations indicate the modulation of AR on p73 and p21 mediated by direct binding of AR to their promoters, and DHT could make these binding more effectively. Conclusions: Our study demonstrates the tumorigenesis role of AR and the inhibitory effect of bicalutamide in AR-positive MSL TNBC both in vitro and in vivo, suggesting that AR inhibition could be a potential therapeutic approach for AR-positive TNBC patients.

DAPK and P16 Methylation and HPV and EBV Infection in Small Cell Carcinoma of Cervix: A Case Report

Purpose: Small cell carcinoma (SMCC) of the cervix is rare and aggressive tumor, often diagnosed in an advanced stage and their prognosis is generally poor. A case of SMCC showing Human Papillomavirus (HPV) and Epstein barr virus (EBV) infection and Death-associated protein kinase (DAPK) and p16 genes methylation is presented. A 74-year-old woman was diagnosed as having stage IB2 of SMCC. Methods: HPV and EBV infection and DAPK and p16 gene methylation were found using molecular approaches. Results: The sample was positive for HPV and EBV infection and showed DAPK and p16 promoter regions methylated Conclusion: Methylation of DAPK and p16 gene could be used as a molecular marker in cervical cancer.

PTEN and p16 genes as epigenetic biomarkers in oral squamous cell carcinoma (OSCC): a study on south Indian population.

Phosphatase and tensin homolog (PTEN) and p16INK4a (p16) genes are tumor suppressor genes, associated with epigenetic alterations. PTEN and p16 promoter hypermethylation is a major epigenetic silencing mechanism leading to cancer. The cooperation between PTEN and p16 in pathogenesis of cancers suggest that their combination might be considered as potential molecular marker for specific subgroups of patients. Hence, the present study aimed to investigate whether PTEN and p16 promoter methylations were involved in oral squamous cell carcinoma (OSCC) in south Indian subjects. DNA methylation quantitative analyses of the two candidate tumor suppressor genes PTEN and p16 were performed by methylation-specific polymerase chain reaction (MSP). Fifty OSCC biopsy samples and their corresponding non-malignant portions as controls were studied comparatively. The methylation status was correlated with the clinical manifestations. Twelve out of 50 patients (24%) were found to be methylated for PTEN gene, whereas methylation of the p16 gene occurred in 19 out of 50 cases (38%). A statistically significant result was obtained (P = <0.0001 and 0.017) for both PTEN and p16 genes. PTEN and p16 promoter methylation may be the main mechanism leading to the low expression of PTEN and p16 genes indicating the progress of tumor development. Our data suggest that a low PTEN and p16 expression due to methylation may contribute to the cancer progression and could be useful for prognosis of OSCC. Therefore, analysis of promoter methylation in such genes may provide a biomarker valuable for early detection of oral cancer.

Human papillomavirus types 16 E1 mRNA is transcribed from P14 early promoter in cervical neoplasms

High-risk human papillomavirus (HR-HPV) persistent infection is responsible for the development of the majority of cervical cancers. The therapy against HPV-associated cancer requires knowledge of the viral gene expression mechanisms. In this study, the polyadenylated polycistronic transcripts containing full-size E1ORF and produced from the early P14 promoter were detected for the first time in cervical tumors with episomal forms of the HPV16 genome. P14-initiated mRNAs were revealed also in precancerous lesions. The amount of P14-initiated transcripts was significantly less compared to transcripts initiated from the major P97 HPV16 promoter in cervical intraepithelial neoplasms and squamous cell carcinomas. The ratios of P97/P14-transcripts determined by qRT-PCR were unique for each clinical sample and varied in quite wide ranges independent of disease progression stages or tumor grade. These data suggest that the levels of P14- and P97-transcripts are regulated independently from each other in cervical neoplasms.

P16-specific DNA methylation by engineered zinc finger methyltransferase inactivates gene transcription and promotes cancer metastasis

BackgroundP16 DNA methylation is well known to be the most frequent event in cancer development. It has been reported that genetic inactivation of P16 drives cancer growth and metastasis, however, whether P16 DNA methylation is truly a driver in cancer metastasis remains unknown.ResultsA P16-specific DNA methyltransferase (P16-dnmt) expression vector is designed using a P16 promoter-specific engineered zinc finger protein fused with the catalytic domain of dnmt3a. P16-dnmt transfection significantly decreases P16 promoter activity, induces complete methylation of P16 CpG islands, and inactivates P16 transcription in the HEK293T cell line. The P16-Dnmt coding fragment is integrated into an expression controllable vector and used to induce P16-specific DNA methylation in GES-1 and BGC823 cell lines. Transwell assays show enhanced migration and invasion of these cancer cells following P16-specific DNA methylation. Such effects are not observed in the P16 mutant A549 cell line. These results are confirmed using an experimental mouse pneumonic metastasis model. Moreover, enforced overexpression of P16 in these cells reverses the migration phenotype. Increased levels of RB phosphorylation and NFκB subunit P65 expression are also seen following P16-specific methylation and might further contribute to cancer metastasis.ConclusionP16 methylation could directly inactivate gene transcription and drive cancer metastasis.Electronic supplementary materialThe online version of this article (doi:10.1186/s13059-015-0819-6) contains supplementary material, which is available to authorized users.

Association between p16 Promoter Methylation and Thyroid Cancer Risk: A Meta-analysis.

The aim of the meta-analysis was to derive a more precise assessment of the association between p16 promoter methylation and thyroid cancer risk. The PubMed, Web of Science databases and Chinese CNKI were searched for relevant articles. Ultimately, seventeen case-control studies were included with a total of 804 thyroid cancer cases and 487 controls analysis by R Software (R version 3.1.2) including meta. Crude odds ratios with 95% confidence intervals were calculated using the random-effects model which were used to assess the strength of relationship between p16 methylation and lung carcinogenesis. Funnel plots were carried out to evaluate publication bias. The meta-analysis results showed that the frequency of p16 promoter methylation in cancer tissue/blood was significantly higher than that normal tissue/ blood (OR=5.46, 95%CI 3.12-9.55, P<0.0001) by random effects model with small heterogeneity. Thus, p16 promoter methylation may be associated with thyroid cancer risk.

Hepatitis B virus X protein induces the histone H3 lysine 9 trimethylation on the promoter of p16 gene in hepatocarcinogenesis

Our previous study showed hepatitis B virus X protein (HBx) suppresses the p16 expression in hepatocarcinogenesis. In this study we explored the relationship between HBx and trimethylation of H3K9 (H3K9me3), and elucidated the underlying mechanisms in HBx inducing the tumor suppressor p16 gene silence. SMMC-7721 and HepG2 hepatoma cell lines were transfected with HBx-expressing plasmid. Immunohistochemistry, Western blotting and real-time polymerase chain reaction, were performed to detect the expressions of HBx, H3K9me3, and jumonji domain-containing protein 2B (JMJd2B). H3K9me3 enrichment on the p16 promoter was measured by immunoprecipitation-PCR (ChIP-PCR) analyses, and 39 cases of hepatitis B virus (HBV) associated-hepatocellular carcinoma (HCC) and corresponding noncancerous liver tissues were also examined. We demonstrated that HBx was able to upregulate H3K9me3 and suppress JMJd2B mRNA and protein levels in SMMC-7721 and HepG2 hepatoma cell lines. JMJd2B, as a specific target of H3K9me3 for demethylation, was inversely correlated with the levels of H3K9me3 in SMMC-7721 (r=−0.666, P<0.05) and HepG2 cells (r=−0.625, P<0.05). The ChIP-PCR data indicated that HBx remarkably increased H3K9me3 on the p16 promoter region. Immunohistochemistry analysis showed that H3K9me3 expression in HBx positive HCC samples were significantly higher than that in HBx negative HCC tissues and were associated with decreased levels of JMJd2B expression. JMJd2B immunoreactivity was also remarkably inversed to that of HBx in HCC tissues (r=−0.630, P<0.05). Our results provide evidence that HBx is able to induce H3K9me3 on the p16 promoter via the decrease of demethylase JMJd2B expression and thus promote the repression of p16 gene expression to enhance hepatocarcinogenesis.

Th22 cells control colon tumorigenesis through STAT3 and Polycomb Repression complex 2 signaling

ABSTRACTTh22 cells traffic to and retain in the colon cancer microenvironment, and target core stem cell genes and promote colon cancer stemness via STAT3 and H3K79me2 signaling pathway and contribute to colon carcinogenesis. However, whether Th22 cells affect colon cancer cell proliferation and apoptosis remains unknown. We studied the interaction between Th22 cells and colon cancer cells in the colon cancer microenvironment. Colon cancer proliferation was examined by flow cytometry analysis and H3 thymidine incorporation. Cell cycle related genes were quantified by real-time PCR and Western blotting. We transfected colon cancer cells with lentiviral vector encoding specific gene shRNAs and used chromatin immunoprecipitation (ChIP) assay to determine the genetic signaling involved in interleukin (IL)-22-mediated colon cancer cell proliferation. We showed that Th22 cells released IL-22 and stimulated colon cancer proliferation. Mechanistically, IL-22 activated STAT3, and subsequently STAT3 bound to the promoter areas of the Polycomb Repression complex 2 (PRC2) components SUZ12 and EED, and stimulated the expression of PRC2. Consequently, the activated PRC2 catalyzed the promoters of the cell cycle check-point genes p16 and p21, and inhibited their expression through H3K27me3-mediated histone methylation, and ultimately caused colon cancer cell proliferation. Bioinformatics analysis revealed that the levels of IL-22 expression positively correlated with the levels of genes controlling cancer proliferation and cell cycling in colon cancer. In addition to controlling colon cancer stemness, Th22 cells support colon carcinogenesis via affecting colon cancer cell proliferation through a distinct histone modification.

Investigating the effects of in utero benzene exposure on epigenetic modifications in maternal and fetal CD-1 mice

Exposure to the ubiquitous environmental pollutant benzene is positively correlated with leukemia in adults and may be associated with childhood leukemia following in utero exposure. While numerous studies implicate oxidative stress and DNA damage as playing a role in benzene-mediated carcinogenicity, emerging evidence suggests that alterations in epigenetic regulations may be involved. The present study aimed to determine whether DNA methylation and/or various histone modifications were altered following in utero benzene exposure in CD-1 mice. Global DNA methylation and promoter-specific methylation of the tumor suppressor gene, p15, were assessed. Additionally, levels of acetylated histones H3, H4, and H3K56, as well as methylated histones H3K9 and H3K27 were assessed by Western blotting. A significant decrease in global DNA methylation of maternal bone marrow was observed following benzene exposure; however no effect on global DNA methylation was detected in fetal livers. Additionally, no effect of benzene exposure was observed on p15 promoter methylation or any measured histone modifications in both maternal bone marrow and fetal livers. These results suggest that the methodology used in the present study did not reveal alterations in DNA methylation and histone modifications following in utero exposure to benzene; however further experimentation investigating these modifications at the whole genome/epigenome level, as well as at later stages of benzene-induced carcinogenesis, are warranted.

High frequency of p16 and p14 promoter hypermethylation and marked telomere instability in salivary gland tumors

Objectivesto investigate p16INK4a and p14ARF tumor suppressor gene methylation status, determine telomere length and assess the importance of these epigenetic and genetic parameters in the development of pleomorphic adenoma and carcinoma ex pleomorphic adenoma of the parotid salivary glands. Materials and MethodsGenomic DNA from paraffin-embedded samples of 50 pleomorphic adenomas and 10 carcinomas ex pleomorphic adenoma was subjected to methylation specific polymerase chain reaction for hypermethylation analyses and real time polymerase chain reaction for the relative telomere length calculations. ResultsPromoter hypermethylation of the two genes was a very frequent event in both neoplasms – between 60% and 90% of samples were hypermethylated – but without significant difference between the groups. The mean relative telomere length in the pleomorphic adenoma group was significantly increased in comparison to the control group (P=0.00), and significantly decreased in comparison to the carcinoma group (P=0.05). Telomeres were also longer in myxoid and cellular histological subtypes of adenomas than in the classic type (P=0.044 and P=0.018, respectively). Longer telomeres were more frequent in tumors with hypermethylated p14ARF alleles (P=0.013). ConclusionPromoter hypermethylations seems to be an important mechanism of p16INK4a and p14ARF inactivation in parotid gland tumors. Telomeric lengthening appears to be involved in the pathogenesis of both benign and malignant tumors of the parotid glands.

Retraction Note to: Role of p16 gene promoter methylation in gastric carcinogenesis: a meta-analysis

This meta-analysis was performed to evaluate the relationships between promoter DNA methylation in tumor suppressor gene p16 and gastric carcinogenesis. The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library and CBM databases were searched for relevant articles published before November 1st, 2013 without any language restrictions. Meta-analysis was conducted using the STATA 12.0 software. Crude odds ratios (ORs) with 95 % confidence intervals (95 % CI) were calculated. Forty-seven clinical cohort studies that met all inclusion criteria were included in this meta-analysis. A total of 2,813 gastric cancer (GC) patients were assessed. Our meta-analysis results revealed that the frequencies of p16 promoter methylation in the GC tissues were higher than those of normal and adjacent tissues (Normal: OR = 23.04, 95 % CI = 13.55–39.15, P < 0.001; Adjacent: OR = 4.42, 95 % CI = 1.66–11.76, P = 0.003; respectively). Furthermore, we observed significant associations of p16 promoter methylation with TNM stage, histologic grade, invasive grade, lymph node metastasis of GC (TNM stage: OR = 3.60, 95 % CI: 2.17–5.98, P < 0.001; Histologic grade: OR = 2.63, 95 % CI: 1.55–4.45, P < 0.001; Invasive grade: OR = 3.44, 95 % CI: 1.68–7.06, P = 0.001; Lymph node metastasis: OR = 2.68, 95 % CI: 1.66–4.32, P < 0.001; respectively). However, there were no correlations of p16 promoter methylation with the TNM stage and Helicobacter pylori (HP) infection of GC (Tumor size: OR = 0.76, 95 % CI: 0.14–4.07, P = 0.746; HP infection: OR = 1.31, 95 % CI: 0.75–2.27, P = 0.342; respectively). Our findings provide empirical evidence that p16 promoter methylation may play an important role in gastric carcinogenesis. Thus, p16 promoter methylation may be a promising potential biomarker for the early diagnosis of GC.

Abstract 5569: p73 dinucleotide polymorphism genotyping of human cancer cell lines

Abstract The p73 gene is a member of the p53 tumor suppressor family. The p73 dinucleotide polymorphism (DNP) (rs1801173) is a G4C14-to-A4T14 linked pair of transitions located in exon 2 between the P1 and P2 gene promoters. The P1 and P2 p73 gene promoters are the transcription initiation sites for mRNAs encoding TAp73 and ΔNp73 isoforms, respectively. Recently, we reported the p73 DNP allele was associated with (1) decreased risk [OR = 0.55, 95%CI = 0.31-0.99] for aggressive prostate cancer (PCa) and (2) increased TAp73/ΔNp73 protein isoform ratios in ten human cancer cell lines. We hypothesize the presence of the p73 DNP allele causes altered p73 promoter usage resulting in increased TAp73/ΔNp73 protein isoform ratios, which could explain the observed decreased risk for PCa aggressiveness. Our ultimate goal is to assess the potential of p73 DNP as a biomarker for lower aggressive PCa risk. Therefore, our initial aim in this study was to determine the p73 DNP genotype in ten additional human cancer cell lines (DU 145, JEG-3, K-562, LNCaP, MDA-MB-231, MDA-MB-468, MRC-5, PC-3, SW48 and U-2OS) not yet characterized for p73 DNP status. We previously reported the p73 DNP genotype of three human cancer cell lines that we used as genotyping controls: Caco-2 (homozygous polymorphic), NCI-H1299 (homozygous wild type), and HepG2 (heterozygous). Cell lines were cultured and genomic DNA was isolated and quantitated. Cell line genomic DNA samples were used in TaqMan Real Time-PCR allelic discrimination assays to determine the p73 DNP genotypes. Our data conclusively determined that DU 145, JEG-3, K-562, LNCaP, MDA-MB-468, MRC-5, SW48 and U-2OS were p73 DNP homozygous wild type, while PC-3 and MDA-MB-231 werw p73 DNP heterozygous. Cell Line p73 DNP GenotypesCELL LINE NAMEP73 DNP GENOTYPEDU145CCJEG-3CCK-562CCLNCaPCCMDA-MB-231CTMDA-MB-468CCMRC-5CCPC-3CTSW48CCU-2OSCC Citation Format: L. Michael Carastro, Kaia K. Hampton, Ricardo A. Cordova Estupinan, Hyun Y. Park, Dongwha Kim, Jong Y. Park. p73 dinucleotide polymorphism genotyping of human cancer cell lines. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5569. doi:10.1158/1538-7445.AM2015-5569