Senescence markers in focal nodular hyperplasia of the liver: pathogenic considerations on the basis of immunohistochemical results.

Focal nodular hyperplasia (FNH) is a polyclonal tumour-like hepatic lesion characterised by parenchymal nodules, connective tissue septa without interlobular bile ducts, pronounced ductular reaction and inflammation. It may represent a response to local arterial hyperperfusion and hyperoxygenation resulting in oxidative stress. We aimed at obtaining closer insight into the pathogenesis of FNH with its characteristic morphologic features. Immunohistochemistry and immunofluorescence microscopy was performed on FNH specimens using antibodies against keratins (K) 7 and 19, neural cell adhesion molecule (NCAM), lamin B1, senescence markers (CDK inhibitor 1/p21Cip1, CDK inhibitor /p16Ink4a, senescence-associated (SA) ß- galactosidase activity), proliferation markers (Ki-67, proliferating-cell nuclear antigen (PCNA)), and the abnormally phosphorylated histone γ-H2AX, indicating DNA double strand breaks; moreover SA ß- galactosidase activity was determined histochemically. Ductular metaplasia of hepatocytes indicated by K7 expression in the absence of K19 plays a major role in the development of ductular reaction in FNH. Moreover, the expression of senescence markers (p21Cip1, p16Ink4a, γ-H2AX, SA ß-galactosidase activity) in hepatocytes and cholangiocytes suggests that stress-induced cellular senescence contributes to fibrosis and inflammation via production of components of the senescence-associated secretory phenotype. Expression of proliferation markers (Ki-67, PCNA) was not enhanced in hepatocytes and biliary cells. Senescence and ductular metaplasia of hepatocytes may thus be involved in inflammation, fibrosis and apoptosis resistance. Hence, fibrosis, inflammation and reduced apoptotic cell death, rather than proliferation (hyperplasia) may be responsible for increased tissue mass and tumour-like appearance of FNH.

Tumor Suppressors RB1 and CDKN2a Cooperatively Regulate Cell-Cycle Progression and Differentiation During Cardiomyocyte Development and Repair.

RATIONALE: Although rare cardiomyogenesis is reported in the adult mammalian heart, whether this results from differentiation or proliferation of cardiomyogenic cells remains controversial. The tumor suppressor genes RB1 (retinoblastoma) and CDKN2a (cyclin-dependent kinase inhibitor 2a) are critical cell-cycle regulators, but their roles in human cardiomyogenesis remains unclear. OBJECTIVE: We hypothesized that developmental activation of RB1 and CDKN2a cooperatively cause permanent cell-cycle withdrawal of human cardiac precursors (CPCs) driving terminal differentiation into mature cardiomyocytes, and that dual inactivation of these tumor suppressor genes promotes myocyte cell-cycle reentry. METHODS AND RESULTS: Directed differentiation of human pluripotent stem cells (hPSCs) into cardiomyocytes revealed that RB1 and CDKN2a are upregulated at the onset of cardiac precursor specification, simultaneously with GATA4 (GATA-binding protein 4) homeobox genes PBX1 (pre-B-cell leukemia transcription factor 1) and MEIS1 (myeloid ecotropic viral integration site 1 homolog), and remain so until terminal cardiomyocyte differentiation. In both GATA4+ hPSC cardiac precursors and postmitotic hPSC-cardiomyocytes, RB1 is hyperphosphorylated and inactivated. Transient, stage-specific, depletion of RB1 during hPSC differentiation enhances cardiomyogenesis at the cardiac precursors stage, but not in terminally differentiated hPSC-cardiomyocytes, by transiently upregulating GATA4 expression through a cell-cycle regulatory pathway involving CDKN2a. Importantly, cytokinesis in postmitotic hPSC-cardiomyocytes can be induced with transient, dual RB1, and CDKN2a silencing. The relevance of this pathway in vivo was suggested by findings in a porcine model of cardiac cell therapy post-MI, whereby dual RB1 and CDKN2a inactivation in adult GATA4+ cells correlates with the degree of scar size reduction and endogenous cardiomyocyte mitosis, particularly in response to combined transendocardial injection of adult human hMSCs (bone marrow-derived mesenchymal stromal cells) and cKit+ cardiac cells. CONCLUSIONS: Together these findings reveal an important and coordinated role for RB1 and CDKN2a in regulating cell-cycle progression and differentiation during human cardiomyogenesis. Moreover, transient, dual inactivation of RB1 and CDKN2a in endogenous adult GATA4+ cells and cardiomyocytes mediates, at least in part, the beneficial effects of cell-based therapy in a post-MI large mammalian model, a finding with potential clinical implications.

Association between rs3088440 (G > A) polymorphism at 9p21.3 locus with the occurrence and severity of coronary artery disease in an Iranian population.

BACKGROUND: Several genome-wide association studies showed that a series of genetic variants located at the chromosome 9p21 locus are strongly associated with coronary artery disease (CAD). RATIONALE AND PURPOSE OF THE STUDY: In the present study, the relationship of rs3088440 (G > A) in cyclin-dependent kinase inhibitor 2A (CDKN2A) gene site with the presence of coronary artery disease (CAD) and its severity was evaluated in an Iranian population. METHODS AND RESULTS: The presence of rs3088440 (G > A) genotypes was assessed by polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) technique in 324 CAD patients and 148 normal controls. rs3088440 (G > A) polymorphism was associated with increased risk of CAD in the total population (adjusted OR = 1.76, 95% CI = 1.10-2.82; p-value = 0.017) or in women (adjusted OR = 2.96, 95% CI = 1.34-6.55; p-value = 0.007), but not in the men (adjusted OR = 1.35, 95% CI = 0.70-2.6; p-value = 0.368). CONCLUSIONS: Our findings suggest that the presence of rs3088440 (G > A) is potentially linked with the risk of CAD and its severity in whole study subjects or in women only, independent of CAD risk factors.

Mutations in CDKN2A and the FGFR3 genes on bladder cancer diagnosis: a systematic review and meta-analysis.

PURPOSE: To determine the association between mutations in CDKN2A and FGFR3 genes and the diagnosis of bladder carcinoma (BCa). METHODS: A systematic search strategy was carried out through MEDLINE, EMBASE, LILACS, CENTRAL and unpublished literature. We included RCTs, cohort, case-control and cross-sectional studies that involved patients > 18-year-old assessing the association between CDKN2A and FGFR3 mutated genes and BCa. The primary outcome was bladder cancer defined by histology of the sample. We assessed the risk of bias with QUADAS2 and performed a meta-analysis with Review Manager v5.3. RESULTS: We found 97 records with the search strategies. After duplicates were removed, six studies were included in meta-analysis. Regarding the association between mutated FGFR3 and bladder cancer, we found an OR 31 95% CI (15-64). However, there was no association for CDKN2A and BCa. CONCLUSION: There is a strong association between FGFR3 mutated gene and the diagnosis of bladder cancer, which has not been observed with CDKN2A. Such a result supports FGFR3 mutated gene as a promissory bladder cancer screening and monitoring biomarker.

Functional Genetic Single-Nucleotide Polymorphisms (SNPs) in Cyclin-Dependent Kinase Inhibitor 2A/B (CDKN2A/B) Locus Are Associated with Risk and Prognosis of Osteosarcoma in Chinese Populations.

BACKGROUND Cyclin-dependent kinase inhibitor 2A/B (CDKN2A/B) encodes several tumor suppressor proteins. Aberrant genetic alterations in CDKN2A/B were found in some malignancies, which were believed to be associated with tumor originating and progression. We hypothesized that CDKN2A/B genetic polymorphisms might be associated with the risk of poorer prognosis of osteosarcoma in Chinese populations. MATERIAL AND METHODS We included 184 validated osteosarcoma cases and 185 cancer-free healthy controls in the study. Five single-nucleotide polymorphisms of CDKN2A/B (rs1063192, rs3218009, rs3217986, rs3217992, and rs3731257) were genotyped and underwent bioinformatic analysis. DNA from osteosarcoma individuals was isolated from frozen peripheral blood and DNA from healthy controls was extracted from fresh prepared peripheral blood. RESULTS An allele of the SNP rs3217992 is predictive for susceptibility to osteosarcoma, and it is associated with poorer prognosis of osteosarcoma. The GA and AA genotypes of rs3217992 are related to elevated risk of osteosarcoma. In addition, the GA and AA genotypes of rs3217992 in CDKN2A might indicate higher stage and increased risk of lung metastasis of osteosarcoma, resulting in worse prognosis. CONCLUSIONS Functional genetic polymorphisms in CDKN2A/B predict the susceptibility and outcome of osteosarcoma in Chinese individuals.

Sec62/Ki67 and p16/Ki67 dual-staining immunocytochemistry in vulvar cytology for the identification of vulvar intraepithelial neoplasia and vulvar cancer: a pilot study.

PURPOSE: The aim of this study was to analyze the diagnostic performance of a newly established immunocytochemical dual-staining protocol for the simultaneous expression of SEC62 and Ki67 in vulvar liquid-based cytology specimens for the identification of vulvar intraepithelial neoplasia (VIN) and vulvar cancer. In addition, we investigated the p16/Ki67 dual stain, which has already been established in cervical cytology. MATERIALS AND METHODS: For this pilot study, residual material from liquid-based cytology was collected retrospectively from 45 women. The presence of one or more double-immunoreactive cells was considered as a positive test result for Sec62/Ki67 and p16/Ki67 dual staining. The test results were correlated with the course of histology. RESULTS: All cases of VIN and vulvar cancer were Sec62/Ki67 and p16/Ki67 dual-stain positive, and normal and low-grade squamous intraepithelial lesions were all negative. The sensitivity of cytology for VIN + cases was 100% (22/22), whereas punch biopsy classified one case of vulvar carcinoma as inflammation. All cases with high-intensity (grades 3 and 4) Sec62 staining in Sec62/Ki67-positive cases were carcinomas. CONCLUSIONS: The results of this study demonstrate that Sec62/Ki67 and p16 Ki67 dual-staining cytology could be a promising adjunctive diagnostic tool for VIN and squamous cell carcinoma, in addition to standard histology.

H2A.Z maintenance during mitosis reveals nucleosome shifting on mitotically silenced genes.

Profound chromatin changes occur during mitosis to allow for gene silencing and chromosome segregation followed by reactivation of memorized transcription states in daughter cells. Using genome-wide sequencing, we found H2A.Z-containing +1 nucleosomes of active genes shift upstream to occupy TSSs during mitosis, significantly reducing nucleosome-depleted regions. Single-molecule analysis confirmed nucleosome shifting and demonstrated that mitotic shifting is specific to active genes that are silenced during mitosis and, thus, is not seen on promoters, which are silenced by methylation or mitotically expressed genes. Using the GRP78 promoter as a model, we found H3K4 trimethylation is also maintained while other indicators of active chromatin are lost and expression is decreased. These key changes provide a potential mechanism for rapid silencing and reactivation of genes during the cell cycle.

P16 is a useful supplemental diagnostic marker of pulmonary small cell carcinoma in small biopsies and cytology specimens.

Pulmonary small cell carcinoma (SCLC) is usually diagnosed in small biopsy or cytological specimens based on cytomorphology; however in ambiguous cases diagnosis requires additional support by immunohistochemistry. While TP53 and RB1 alterations with secondary overexpression of p16 are mainstay events in SCLC pathogenesis, diagnostic value of p16-positivity in the diagnosis of SCLC has not yet been fully investigated. We examined the expression of p16, CD56, synaptophysin (SYP), chromogranin A and thyroid transcription factor-1 (TTF1) in a series of pulmonary and extrapulmonary small cell carcinomas, pulmonary carcinoids and non-small cell lung carcinomas, and compared diagnostic performance of these markers in the diagnosis of SCLC. P16 was positive in 95 of 101 SCLCs, and displayed highest diagnostic sensitivity of ~94%. Composite biomarkers CD56+p16+TTF1 and CD56+p16+SYP were both able to detect correctly all SCLC cases. Importantly, three (~3%) SCLC cases completely negative for all conventional markers displayed diffuse positivity for p16. CD56 and p16 demonstrated highest concordance between paired small biopsy and cytology specimens. 50% of squamous cell carcinomas, ~41% of adenocarcinoma/NSCLC-favour adenocarcinoma cases, and ~93% of extrapulmonary small cell carcinomas also showed p16-positivity. Combination of CD56, p16 and TTF1 produced diagnostic classifier that outperformed best single marker CD56 in differential diagnosis between SCLC and NSCLC. In conclusion, in the appropriate morphological context p16 represents a useful supplementary marker for diagnosis of SCLC, even in cases where only cytological material is available.

The H3K27me3 demethylase JMJD3 contributes to the activation of the INK4A-ARF locus in response to oncogene- and stress-induced senescence.

The tumor suppressor proteins p16INK4A and p14ARF, encoded by the INK4A-ARF locus, are key regulators of cellular senescence. The locus is epigenetically silenced by the repressive H3K27me3 mark in normally growing cells, but becomes activated in response to oncogenic stress. Here, we show that expression of the histone H3 Lys 27 (H3K27) demethylase JMJD3 is induced upon activation of the RAS-RAF signaling pathway. JMJD3 is recruited to the INK4A-ARF locus and contributes to the transcriptional activation of p16INK4A in human diploid fibroblasts. Additionally, inhibition of Jmjd3 expression in mouse embryonic fibroblasts results in suppression of p16Ink4a and p19Arf expression and in their immortalization.

Immunohistochemical study of cyclin A and p16 expression in patients with renal cell carcinoma.

PURPOSE: Renal cell carcinoma (RCC) is the most common malignant kidney tumor in adults. Dysregulation of the cell cycle can lead to cancer development. In this study, the mitosis-associated cyclin A and p16, a negative controller, were investigated as potential key points in the RCC development. METHODS: This retrospective study included 74 patients with RCC. The expression of cyclin A and p16 and their correlation to histopathological parameters (TNM stage, histological subtype, nuclear grade, tumor size), gender, age, and clinical outcome were studied and analyzed. RESULTS: The highest median value for cyclin A (40%; range 0-70)) and for p16 (57.5%); range 35-80) were found in the papillary histological subtype. Survival analysis showed that in the group of patients that had died before September 2015, the median value for cyclin A was 20% (range 0-60), which was significantly higher than 5% (range 0-70), found in the group of patients that survived (p=0.019). CONCLUSIONS: In relation to the histological subtype, the papillary type of RCC was associated with a significantly higher expression of cyclin A and p16 compared to other subtypes of RCC. High expression of cyclin A indicated worse prognosis, therefore cyclin A could be considered to be a significant prognostic marker.

Two main genetic pathways lead to the transformation of chronic lymphocytic leukemia to Richter syndrome.

Richter syndrome (RS) occurs in up to 15% of patients with chronic lymphocytic leukemia (CLL). Although RS, usually represented by the histologic transformation to a diffuse large B-cell lymphoma (DLBCL), is associated with a very poor outcome, especially when clonally related to the preexisting CLL, the mechanisms leading to RS have not been clarified. To better understand the pathogenesis of RS, we analyzed a series of cases including 59 RS, 28 CLL phase of RS, 315 CLL, and 127 de novo DLBCL. RS demonstrated a genomic complexity intermediate between CLL and DLBCL. Cell-cycle deregulation via inactivation of TP53 and of CDKN2A was a main mechanism in the histologic transformation from CLL phase, being present in approximately one half of the cases, and affected the outcome of the RS patients. A second major subgroup was characterized by the presence of trisomy 12 and comprised one third of the cases. Although RS shared some of the lesions seen in de novo DLBCL, its genomic profile was clearly separate. The CLL phase preceding RS had not a generalized increase in genomic complexity compared with untransformed CLL, but it presented clear differences in the frequency of specific genetic lesions.

Asynchronous glands in secretory pattern endometrium: clinical associations and immunohistological changes.

AIMS: The significance and pathogenesis of irregular or asynchronous maturation within endometrial glands remains uncertain. The aim of this study was to investigate differences in epithelial hormone receptor immunoreactivity and stromal cell calretinin, CD34 and p16 expression in morphologically normal secretory endometrium and in asynchronous (non-secretory) endometrial glands (AEGs). METHODS AND RESULTS: Nineteen consecutive endometrial specimens showing AEGs were examined. The mean age of the patients was 42.8 years, and the most common presenting symptom was menorrhagia. Immunohistological expression of oestrogen receptor (ER) α, of ERß and of progesterone receptor (PR) were compared in normal secretory glands and in AEGs. Stromal cell expression of calretinin, CD34 and p16 was also investigated. In contrast to normal secretory glands, the epithelial cells lining AEGs were usually ERα/PR-positive and showed significantly increased ERß expression. Altered calretinin and CD34 expression within functional layer stromal cells was seen in five and two cases, respectively, but there were no differences in stromal cell immunoreactivity around AEGs. CONCLUSIONS: The most common clinical symptom associated with AEGs in this study was menorrhagia. Aberrant hormone receptor expression in AEGs suggests a localized, possibly clonal, defect in epithelial maturation. There were no immunophenotypic changes to suggest that AEGs are related to a primary endometrial stromal deficiency.

p16INK4a Status and Response to Induction Low-Dose Fractionated Radiation in Advanced Head and Neck Cancer.

OBJECTIVE: To evaluate the impact of p16INK4a (p16) expression on clinical efficacy of induction low-dose fractionated radiation therapy (LDFRT) with concurrent chemotherapy in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN). STUDY DESIGN: Historical cohort study. SETTING: Tertiary medical center. METHODS: A total of 66 Patients with locally advanced SCCHN were enrolled in 2 clinical trials using paclitaxel, carboplatin, and concurrent LDFRT induction therapy. Patients were evaluated for response to induction by a multidisciplinary team and then were given definitive treatment. Adequate tissue samples from the pretreatment biopsies of 42 individuals were identified and analyzed for p16 expression. Expression was correlated with clinical outcomes. RESULTS: Of 42 tumors, 15 (35.7%) were positive for p16. Patients with p16-positive tumors had improved response to induction, but this was not statistically significant (P = .06). Five-year overall survival was 80% in p16-positive patients and 58% in p16-negative patients (P = .025). CONCLUSIONS: p16 Expression affects treatment response in patients treated with induction LDFRT with concurrent chemotherapy. This is similar to results reported for standard induction chemotherapy.

Comparison of cancer-associated genetic abnormalities in columnar-lined esophagus tissues with and without goblet cells.

OBJECTIVE: To determine and compare the frequency of cancer-associated genetic abnormalities in esophageal metaplasia biopsies with and without goblet cells. BACKGROUND: Barrett's esophagus is associated with increased risk of esophageal adenocarcinoma (EAC), but the appropriate histologic definition of Barrett's esophagus is debated. Intestinal metaplasia (IM) is defined by the presence of goblet cells whereas nongoblet cell metaplasia (NGM) lacks goblet cells. Both have been implicated in EAC risk but this is controversial. Although IM is known to harbor genetic changes associated with EAC, little is known about NGM. We hypothesized that if NGM and IM infer similar EAC risk, then they would harbor similar genetic aberrations in genes associated with EAC. METHODS: Ninety frozen NGM, IM, and normal tissues from 45 subjects were studied. DNA copy number abnormalities were identified using microarrays and fluorescence in situ hybridization. Targeted sequencing of all exons from 20 EAC-associated genes was performed on metaplasia biopsies using Ion AmpliSeq DNA sequencing. RESULTS: Frequent copy number abnormalities targeting cancer-associated genes were found in IM whereas no such changes were observed in NGM. In 1 subject, fluorescence in situ hybridization confirmed loss of CDKN2A and amplification of chromosome 8 in IM but not in a nearby NGM biopsy. Targeted sequencing revealed 11 nonsynonymous mutations in 16 IM samples and 2 mutations in 19 NGM samples. CONCLUSIONS: This study reports the largest and most comprehensive comparison of DNA aberrations in IM and NGM genomes. Our results show that IM has a much higher frequency of cancer-associated mutations than NGM.

The prognostic value of CDKN2A hypermethylation in colorectal cancer: a meta-analysis.

BACKGROUND: The prognostic value of CDKN2A promoter hypermethylation in colorectal cancer remains controversial. We systematically reviewed the evidence for assessment of CDKN2A methylation in colorectal cancer to elucidate this issue. METHODS: Pubmed, Embase and ISI web of knowledge were searched to identify eligible studies to evaluate the association of CDKN2A hypermethylation and overall survival and clinicopathological features of colorectal cancer patients. Combined hazard ratios (HRs) or odds ratios (ORs) with 95% confidence interval (95% CI) were pooled using a random-effects model. RESULTS: A total of 11 studies encompassing 3440 patients were included in the meta-analysis. CDKN2A hypermethylation had an unfavourable impact on OS of patients with colorectal cancer (HR 1.65, 95% CI 1.29-2.11). Subgroup analysis indicated that CDKN2A hypermethylation was significantly correlated with OS in Europe (HR 1.49; 95% CI 1.28-1.74) and Asia (HR 3.30; 95% CI 1.68-6.46). Furthermore, there was a significant association between CDKN2A hypermethylation and lymphovascular invasion (OR 1.68, 95% CI 1.15-2.47), lymph node metastasis (OR 1.68, 95% CI 1.09-2.59) and proximal tumour location (OR 2.09, 95% CI 1.34-3.26) of colorectal cancer. CONCLUSION: This meta-analysis indicated that CDKN2A hypermethylation might be a predictive factor for unfavourable prognosis of colorectal cancer patients.

Detection of a rare CDKN2A intronic mutation in a Hungarian melanoma-prone family and its role in splicing regulation.

BACKGROUND: The major locus for melanoma predisposition is the cell cycle regulatory CDKN2A gene on chromosome 9p21. However, the frequency of germline coding mutations of the CDKN2A gene is lower than expected in melanoma-prone families linked to chromosome 9p21. OBJECTIVES: To investigate whether the rare IVS1+37 G/C intronic mutation of the CDKN2A gene, recently identified in a Hungarian melanoma-prone family, influences mRNA splicing regulation. METHODS: CDKN2A minigenes containing the wild-type and the mutant intronic sequence were created and transfected into HeLa cells with the aim of studying the mRNA transcripts. RESULTS: The results revealed the emergence of a differential splicing pattern from the wild-type and the mutant minigene, suggesting that this mutation may alter the splicing of CDKN2A primary mRNA and therefore might have a pathogenetic role in familial melanoma. CONCLUSIONS: We believe that these results confirm the importance of the identification and characterization of CDKN2A intronic mutations with a view to improving our understanding of the pathogenesis, and explain why the frequency of germline coding mutations of the CDKN2A gene is lower than expected in melanoma-prone families linked to chromosome 9p21.

Analysis of p16(CDKN2A) methylation and HPV-16 infection in oral mucosal dysplasia.

OBJECTIVE: The purpose of this study was to investigate the relationship between p16(CDKN2A) methylation and epithelial dysplasia (ED). We also evaluated the expressions of proteins related to methylation (DNMT3B and DNMT1). Finally, we tested whether HPV-16/18 or the dmt3b (C46359T) polymorphism is associated with p16(CDKN2A) methylation status. METHODS: To test the hypothesis, a case-control study with 72 (control, n = 24; ED, n = 48) tissue samples from subjects was performed. Methylation-specific PCR, RFLP, and immunohistochemical analyses were performed to evaluate p16(CDKN2A) methylation status, dmt3b (C46359T) genotyping, and protein levels, respectively. RESULTS: The methylation of p16(CDKN2A) and HPV-16 was associated with ED gradation (p = 0.001 and 0.002, respectively). In addition, most HPV-16-positive samples (77.8%) exhibited p16(CDKN2A) methylation; however, changes in DNMT3B and DNMT1 protein levels were not observed in HPV-positive samples. Neither HPV-18 nor the dmt3b polymorphism was associated with p16(CDKN2A) methylation. CONCLUSIONS: There is an association between the presence of HPV-16 in ED and the occurrence of p16(CDKN2A) methylation. Both variables are also associated with ED development, but further studies are necessary to clarify if they operate independently and if they have any impact on OD malignization.

Germline melanoma susceptibility and prognostic genes: a review of the literature.

In recent years, there have been increasing efforts to identify germline genetic variants that may alter melanoma susceptibility and prognosis. The findings of these studies have indicated the presence of rare, high-penetrance alleles with large effects, such as CDKN2A and CDK4, more common, moderately penetrant genes like MC1R, and very common, low-penetrance polymorphisms with small effects that are related to pigmentation, nevus count, immune responses, DNA repair, metabolism, and the vitamin D receptor. The study of these low-penetrance single nucleotide polymorphisms is relatively new; thus many of them are termed 'candidate melanoma susceptibility or prognostic genes.' This review summarizes the research on germline polymorphisms that have been implicated in melanoma susceptibility and prognosis in order to provide a framework for additional studies to meet the ultimate goal of predicting a patient's risk of, and prognosis in, cutaneous malignant melanoma.

Comprehensive epigenetic analysis using oral rinse samples: a pilot study.

PURPOSE: To prove that chromatin immunoprecipitation assay can be performed with oral rinse samples and to develop a protocol for comprehensive analysis of functional interactions among DNA methylation, histone modification, and gene expression using such samples. MATERIALS AND METHODS: Eleven cancer cell lines and oral rinse samples from 10 patients with oral squamous cell carcinoma and 3 healthy subjects were examined. The expression of CDKN2A, a tumor suppressor gene, was determined by reverse transcription/polymerase chain reaction and immunohistochemistry. Promoter DNA methylation was assessed by methylation-specific polymerase chain reaction. Chromatin modifications were analyzed by a chromatin immunoprecipitation assay using antibodies for dimethylation and acetylation of lysine 9 of histone H3. RESULTS: Epigenetic control of CDK2NA was observed in vitro in 11 cancer cell lines. Using the present protocol, comprehensive epigenetic analysis could be successfully performed with oral rinse samples. All patients were comfortable using the prescribed amount (16 mL) of normal saline to rinse their mouths. Nine patients (90%) and 1 healthy subject (33%) showed dimethylation of lysine 9 of histone H3. Moreover, 8 patients (80%) showed hypoacetylation of lysine 9 of histone H3, which was not observed in healthy subjects. CONCLUSIONS: The present study showed for the first time that chromatin modifications can be analyzed using oral rinse samples by chromatin immunoprecipitation analysis. To evaluate the contribution of histone modifications for carcinogenesis of oral squamous cell carcinoma, studies including a larger number of subjects should be conducted in the future.