KIF1A and EDNRB are differentially methylated in primary HNSCC and salivary rinses

Silencing of tumor suppressor genes plays a vital role in head and neck carcinogenesis. In this study, we aimed to evaluate to the utility of aberrant promoter hypermethylation for detection in a panel of 10 genes (KIF1A, EDNRB, CDH4, TERT, CD44, NISCH, PAK3, VGF, MAL and FKBP4) in head and neck squamous cell carcinoma (HNSCC) via a candidate gene approach. We investigated methylation of the gene promoters by bisulfite modification and quantitative methylation‐specific PCR (Q‐MSP) in a preliminary study of a limited cohort of salivary rinses from healthy subjects (n = 61) and patients with HNSCC (n = 33). The methylation status of 2 selected genes (EDNRB and KIF1A) were then analyzed in 15 normal mucosa samples from a healthy population, 101 HNSCC tumors and the corresponding salivary rinses from 71 out of the 101 HNSCC patients were collected before treatment. The promoter regions of CDH4, TERT, VGF, MAL, FKBP4, NISCH and PAK3 were methylated in normal salivary rinses while no methylation of CD44 was observed in either normal salivary rinses or tumor samples. However, KIF1A and EDNRB were methylated in 98 and 97% of primary HNSCC tissues respectively and were only methylated in 2 and 6.6% of normal salivary rinses. In addition, KIF1A and EDNRB were methylated in 38 and 67.6% of salivary rinses from HNSCC patients, respectively. Promoter hypermethylation of KIF1A and EDNRB is a frequent event in primary HNSCC, and these genes are preferentially methylated in salivary rinses from HNSCC patients. KIF1A and EDNRB are potential biomarkers for HNSCC detection.     

Promoter hypermethylation profile of cell cycle regulator genes in pituitary adenomas

Aberrant hypermethylation of CpG islands in the promoter region plays a causal role in the inactivation of various key genes involved in the cell cycle regulatory cascade, which could result in a loss of cell cycle control. The aim of the present study was to examine in more detail the prevalence and role of the promoter methylation of genes with a proven involvement in the cell cycle regulation of pituitary adenomas, since their tumorigenesis has not yet been clearly defined. We profiled the CpG island methylation status of a series of well-characterized cell cycle regulation genes: the RB1, p14 ^ARF , p15 ^INK4b , p16 ^INK4a , p21 ^Waf1/Cip1 , p27 ^Kip1 , and p73 genes, in 34 pituitary adenomas as determined by a methylation-specific polymerase chain reaction assay. Promoter hypermethylation of the RB1, p14 ^ARF , p15 ^INK4b , p16 ^INK4a , p21 ^Waf1/Cip1 , p27 ^Kip1 , and p73 genes was detected in 12 (35%), 2 (6%), 11 (32%), 20 (59%), 1 (3%), 0 (0%), and 4 (12%) of the adenomas, respectively. In total, 88% (30 of 34) of the adenomas displayed methylation of at least one of such cell cycle regulatory genes, especially methylation of the member genes of the RB1 pathway (29 of 34; 85%). Promoter hypermethylation of p15 ^INK4b coincided with RB1 and/or p16 ^INK4a methylation, whereas RB1 and p16 ^INK4a methylations tended to be mutually exclusive (p = 0.0048). Furthermore, promoter hypermethylations of p14 ^ARF , p21 ^Waf1/Cip1 , and p73 (not belonging to the member genes of the RB1 pathway) were also coincident with RB1 and/or p16 ^INK4a methylation except in one p73 methylated case. In contrast, none of the clinicopathological features, including the cell proliferation index, was significantly correlated with any particular methylation status. Our results suggested that aberrant hypermethylation of the key cell cycle regulatory genes occurs at a relatively high frequency in pituitary adenomas, especially in RB1 pathway genes with promoter hypermethylation of the p16 ^INK4a gene being the most common deregulation. We further obtained evidence to indicate that RB1 and p16 ^INK4a methylations tended to be mutually exclusive, but did occasionally coincide with other cell cycle regulation gene methylations.     

Up-regulation of expression and lack of 5' CpG island hypermethylation of <Emphasis Type="Italic">p16 INK4a</Emphasis>in HPV-positive cervical carcinomas

Background  

High risk type human papilloma viruses (HR-HPV) induce carcinomas of the uterine cervix by expressing viral oncogenes E6 and E7. Oncogene E7 of HR-HPV disrupts the pRb/E2F interaction, which negatively regulates the S phase entry. Expression of tumor suppressor p16^ink4a drastically increases in majority of HR-HPV associated carcinomas due to removal of pRb repression. The p16^ink4a overexpression is an indicator of an aberrant expression of viral oncogenes and may serve as a marker for early diagnostic of cervical cancer. On the other hand, in 25–57% of cervical carcinomas hypermethylation of the p16 INK4a promoter has been demonstrated using a methylation-specific PCR, MSP. To evaluate a potential usage of the p16 INK4a 5' CpG island hypermethylation as an indicator of tumor cell along with p16^ink4a overexpression, we analyzed the methylation status of p16 INK4a in cervical carcinomas     

Quantitative evaluation of p16(INK4a) promoter methylation using pyrosequencing in de novo diffuse large B-cell lymphoma

The p16^INK4a tumor suppressor gene can be inactivated by a variety of events including promoter hypermethylation. In diffuse large B-cell lymphoma (DLBCL), p16^INK4a methylation has been associated with advanced disease stage and higher IPI. The prognostic impact of p16^INK4a methylation in DLBCL remains unclear; however, it has been suggested to correlate with inferior outcome. To further investigate the clinical impact of p16^INK4a methylation in DLBCL, promoter methylation of this gene was assessed quantitatively by pyrosequencing. Forty-two of 113 (37%) DLBCL patients with methylation level above 5% were categorized as methylated and subsequently divided into low, intermediate and high methylation categories. Overall, no association was shown between the extent of p16^INK4a methylation and patients’ clinical characteristics, except disease stage (P = 0.049). Moreover, we could not reveal any impact of p16^INK4a methylation on lymphoma-specific survival. Although >25% of p16^INK4a methylation correlated with a better progression-free survival (P = 0.048) in patients <65 years old, the significance of this finding, if any, needs to be further investigated. In conclusion, our finding questions the role of p16^INK4a promoter methylation as a negative prognostic factor in DLBCL.     

Analysis of the methylation patterns of the p16 INK4A , p15 INK4B , and APC genes in gastric adenocarcinoma patients from a Brazilian population

Gastric cancer is a major public health problem in Pará state, where studies suggest complex genetic and epigenetic profiles of the population, indicating the need for the identification of molecular markers for this tumor type. In the present study, the methylation patterns of three genes [p16 ^INK4A , p15 ^INK4B , and adenomatous polyposis coli (APC)] were assessed in patients with gastric adenocarcinoma from Pará state in order to identify possible molecular markers of gastric carcinogenesis. DNA samples from tumoral and non-tumoral gastric tissues were modified with sodium bisulfite. A fragment of the promoter region of each gene was amplified and sequenced, and samples with more than 20 % of methylated CpG sites were considered hypermethylated. The correlation between the methylation pattern of the selected genes and the MTHFR C677T polymorphism, as well as the relationship between APC and CDH1 methylation, were evaluated. The results suggest that APC hypermethylation is an age-specific marker of gastric carcinogenesis, and the concordance of this event with CDH1 hypermethylation suggests that the Wnt pathway has an important role in gastric carcinogenesis. While the hypermethylation pattern of p15 ^INK4B seems to be an earlier event in this type of tumor, the hypomethylated status of this gene seems to be correlated to the C677T MTHFR TT genotype. On the other hand, the observed pattern of p16 ^INK4A hypermethylation suggests that this event is a good marker for the gastric cancer pathway in the Pará state population.     

DNA methylation in small lung adenocarcinoma with bronchioloalveolar carcinoma components

We examined the methylation status in 100 specimens of lung adenocarcinomas measuring 2 cm or less and with bronchioloalveolar carcinoma (BAC) components (Noguchi types A–C) and then compared the methylation status between noninvasive tumors (Noguchi type A or B) and invasive tumors (Noguchi type C). Methylation-specific PCR was used to determine the methylation statuses of p16^INK4a, RASSF1A, CDH13, RARβ, and Cyclin D2. The methylation index that was regarded as representing the degree of methylation was calculated. We also determined the mutational statuses of EGFR exons 19 and 21 using a PCR-based method. A multivariate analysis showed that the aberrant methylation of p16^INK4a, RASSF1A, and CDH13 was significantly more frequent in invasive tumors than in noninvasive tumors [p16^INK4a, 36.5% versus (vs.) 8.3%, P = 0.0023; RASSF1A, 46.2% vs. 14.6%, P = 0.0012; CDH13, 42.3% vs. 10.4%, P = 0.0006]. The methylation index was significantly higher in invasive tumors than in noninvasive tumors (P = 0.004). The methylation of p16^INK4a was significantly more frequent in EGFR wild-type tumors than in EGFR mutant tumors (P = 0.021). Our results indicate the involvement of epigenetic alterations in the progression of adenocarcinoma with BAC components.     

Promoter hypermethylation of p14 ARF,RB, and INK4 gene family in hepatocellular carcinoma with hepatitis B virus infection

Both hepatitis B virus (HBV) and gene methylation play important roles in hepatocarcinogenesis. However, their association between HBV infection and gene methylation is not fully understood. Cell cycle control involving RB1 gene-related cell inhibitors is one of the main regulatory pathways were reported to be altered in hepatocellular carcinoma (HCC). The purpose of this research is to assess the methylation status of p14 ^ARF and INK4 gene family (p14 ^ARF , p15 ^INK4B , p16 ^INK4A , and p18 ^INK4C ) in HCC with HBV infection and HCC without it, and discuss possible role of HBV-induced hypermethylation in the mechanism of hepatocarcinogenesis. Methylation status of RB, p14 ^ARF , and INK4 gene family in 64 case of HCC with HBV infection and 24 cases without it were detected by methylation-specific polymerase chain reaction, and HBV-DNA of the plasma were detected by quantitative real-time polymerase chain reaction. p14 ^ARF , p15 ^INK4B , p16 ^INK4A , and RB hypermethylation were observed in 30 (34.1 %), 50 (56.8 %), 62 (70.5 %), and 24(27.3 %) of 88 hepatocellular carcinomas, respectively. Methylation frequencies of them between HCC with HBV infection and HCC without it were 43.8 % versus 8.3 % (p14 ^ARF ), 68.9 % versus 25 % (p15 ^INK4B ), 90.6 % versus 16.7 % ( p16 ^INK4A ), and 28.1 % versus 25 % (RB), respectively. In HBV-associated HCC, the numbers of methylated genes were also more than HCC without virus infection, more than two methylated genes were seen in 48 of 64 (75 %) cases; more than three methylated genes were found in 32 of 64 (50 %); correspondently, no one case has more than two genes methylated. p18 ^INK4C methylation product was not found in cancerous or non-cancerous tissues of 88 HCC. HBV infection is associated with p14 ^ARF , p15 ^INK4B , p16 ^INK4A , and RB gene methylation (P?=?0.048, 0.035, 0.02); HBV-DNA replication is associated with p14 ^ARF , p15 ^INK4B , p16 ^INK4A , and RB gene methylation (P?=?0.048, 0.035, 0.02); high rate of p14 ^ARF , p15 ^INK4B , and p16 ^INK4A in HCC with HBV infection suggests that HBV-induced hypermethylation may be one of the mechanisms of HBV involved in hepatocellular carcinogenesis.     

Validation of methylation markers for diagnosis of oral cavity cancer

PurposeActivation of proto-oncogenes and inactivation of tumour suppressor genes are the major genetic alterations involved in carcinogenesis. The increase in methylation at the promoter region of a tumour suppressor gene can lead to gene inactivation, selecting cells with proliferative advantage. Thus, promoter hypermethylation is considered a marker in a variety of malignant tumours, including oral cavity.Experimental designThe methylation pattern of eight genes was evaluated in 40 oral cavity squamous cell carcinomas (OSCCs) and 40 saliva samples from healthy individuals by Q-MSP. Different combinations of genes were also assessed in order to identify gene panels that could better distinguish between OSCC and saliva samples.ResultsCCNA1, DAPK, DCC and TIMP3 methylation were highly specific for being found in the OSCC samples. Moreover, the combination of these genes improved detection when compared with single markers, reaching values of 92.5% for sensitivity and specificity (when using the panel CCNA1, DCC, TIMP3). Moreover, DAPK, DCC and TIMP3 were hypermethylated in nearly 90% of clinically T1 and T2 cases.ConclusionThe pursuing of this panel of hypermethylated genes is an important tool for the detection of individuals with OSCC. Moreover, the identification of these markers in early stages of OSCC shows the feasibility of using the panel on saliva as possible biomarkers for early diagnosis. The lack of association between the methylation status of these genes and clinical characteristics shows that they are able to distinguish OSCC cases irrespective of social and clinical factors (gender, age, human papillomavirus (HPV) status, clinical stage, vascular embolisation and perineural invasion).     

p16(INK4a) promoter hypermethylation in oral scrapings of oral squamous cell carcinoma risk patients

Aberrant promoter hypermethylation is common in oral squamous cell carcinoma (OSCC) and may be useful as a marker for cancer cells. The aim of our study was to assess whether the detection of hypermethylation of the promoter region of p16(INK4a) in oral cytological samples could be a marker in patients with risk of developing an OSCC. Hypermethylation was detected in 20% (29/145) of the cases analyzed. These findings provide further evidence that the inactivation of p16(INK4a), due to methylation, is an early event in the carcinogenic pathway of OSCC.     

Geographic variation and environmental conditions as cofactors in Chlamydia psittaci association with ocular adnexal lymphomas: a comparison between Italian and African samples

A particular extra‐nodal lymphoma type arises from B cells of the marginal zone (MZ) of mucosa‐associated lymphoid tissue (MALT). The aetiology of MZ lymphomas suggests that they are associated with chronic antigenic stimulation by microbial pathogens, among which Helicobacter pylori‐associated gastric MALT lymphoma is the best studied. Recently, MALT lymphomas have been described in the context of chronic conjunctivitis, which can be associated with Chlamydia spp. infection. Studies from Italy showed the presence of Chlamydia psittaci in 87% of ocular adnexal lymphomas (OAL), and C. psittaci has been described in a large part of samples from Austria and Korea as well. However, this finding was not always confirmed by other studies, suggesting that the association with C. psittaci may depend on geographic heterogeneity. Interestingly, none of the studies up to now has been carried out in the African population, where a strong association between infectious agents and the occurrence of human neoplasms has been reported. This study was designed to investigate the possible association of Chlamydia psittaci in cases retrieved from Kenya, compared to cases from Italy. Our results showed that there was a marked variation between the two geographical areas in terms of association with C. psittaci, as 17% (5/30) of the samples from Italy were positive for C. psittaci, whereas no association with this pathogen was observed in any of the African samples (0/9), suggesting that other cofactors may determine the OAL occurrence in those areas. OAL cases are often characterized by down‐regulation of p16/INK4a expression and promoter hypermethylation of the p16/INK4a gene. Our results showed a partial methylation of p16/INK4a promoter in C. psittaci‐negative cases, whereas no hypermethylation of this gene was found in C. psittaci‐positive cases, suggesting that mechanisms other than promoter hypermethylation lead to p16/INK4a silencing in C. psittaci‐positive cases. We may conclude that the role of epidemiologic, environmental and genetic factors, must be considered in the aetiology of this disease. Copyright © 2009 John Wiley & Sons, Ltd.     

Promotor hypermethylation of p14ARF is a key alteration for progression of oral squamous cell carcinoma

We investigated the promotor hypermethylation status of multiple genes in 49 oral squamous cell carcinomas (OSCC), using the methylation-specific PCR (MSP) assay. The genes examined included p16INK4a, p14ARF, RB1, p21Waf1, p27Kip1, PTEN, p73, 0(6)-MGMT, and GST-P. Detailed clinicopathological data, such as patient age, sex, tobacco use, alcohol consumption, lesion site, degree of tumor differentiation, tumor size, presence of lymph node metastasis, and clinical stage, were collected for all 49 samples. Overall, gene methylation was detected in 46.9% (23/49) of samples and was closely correlated with tobacco use or/and alcohol consumption. Of the genes investigated, p16INK4a, p14ARF, 0(6)-MGMT, RB1, PTEN, and p27Kip1 were found to be methylated in 34.7%, 20.4%, 12.2%, 10.2%, 6.1%, and 4.1% of these 49 tumors, respectively, but methylation of p21Waf1, p73, and GST-P was not detected at all. Methylation frequencies were much higher for each gene when computed among informative cases only. Concurrent promotor hypermethylation of p16INK4a and p14ARF correlated significantly with tumor size, lymph node metastasis, and stage III/IV advanced OSCC; p14ARF hypermethylation, in particular, was significantly associated with both lymph node metastasis and late clinical stage. Our results suggest that DNA methylation of multiple genes, especially hypermethylation of the p14ARF promoter, is common in OSCC and is associated with the use of tobacco and/or alcohol consumption. For this type of cancer, the data further implicates gene methylation as playing an important role in tumor progression.     

p16INK4, pRB,p53 and cyclin D1 expression and hypermethylation of CDKN2 gene in thymoma and thymic carcinoma

There have been few reports on genetic alterations in thymomas. To investigate the expression of p16^INK4A, RB, p53 and cyclin D1 in thymomas, we first examined 36 thymomas (non-invasive type, 16 cases; invasive type, 20 cases) and 3 thymic carcinomas, using immunohistochemistry. Abnormal expression of p16^INK4A, RB, p53 and cyclin D1 was observed in 18, 8, 10 and 7 cases, respectively. Only a subgroup of invasive thymomas and thymic carcinomas showed an inverse correlation between p16^INK4A and RB expression. Subsequently, we examined the 36 thymomas and 4 thymic carcinomas for mutations in p53 and CDKN2 genes, using PCR-SSCP and direct-sequencing analyses. No mutation of these genes was detected in the thymomas and thymic carcinomas examined. A polymorphism in the 3′ untranslated region of exon 3 of CDKN2 was detected in 5 cases of thymoma. We searched for hypermethylation in the promoter region of CDKN2, observing it in 4 thymomas and 1 thymic carcinoma. Our data suggest that, unlike other more common cancers, alteration of the p53 gene may not play a significant role in the tumorigenesis of thymoma. However, inactivation of p16^INK4A and RB may play a role in the progression of thymoma and thymic carcinoma. Int. J. Cancer 73:639–644, 1997. © 1997 Wiley-Liss, Inc.     

A survey of methylated candidate tumor suppressor genes in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a rare malignancy with unique genetic, viral and environmental characteristic that distinguishes it from other head and neck carcinomas. The clinical management of NPC remains challenging largely due to the lack of early detection strategies for this tumor. In our study, we have sought to identify novel genes involved in the pathogenesis of NPC that might provide insight into this tumor's biology and could potentially be used as biomarkers. To identify these genes, we studied the epigenetics of NPC by characterizing a panel of methylation markers. Eighteen genes were evaluated by quantitative methylation‐specific polymerase chain reaction (PCR) in cell lines as well as in tissue samples including 50 NPC tumors and 28 benign nasopharyngeal biopsies. Significance was evaluated using Fisher's exact test and quantitative values were optimized using cut off values derived from receiver–operator characteristic curves. The methylation status of AIM1, APC, CALCA, deleted in colorectal carcinomas (DCC), DLEC, deleted in liver cancer 1 (DLC1), estrogen receptor alpha (ESR), FHIT, KIF1A and PGP9.5 was significantly associated with NPC compared to controls. The sensitivity of the individual genes ranged from 26 to 66% and the specificity was above 92% for all genes except FHIT. The combination of PGP9.5, KIF1A and DLEC had a sensitivity of 84% and a specificity of 92%. Ectopic expression of DCC and DLC1 lead to decrease in colony formation and invasion properties. Our results indicate that methylation of novel biomarkers in NPC could be used to enhance early detection approaches. Additionally, our functional studies reveal previously unknown tumor suppressor roles in NPC.     

Cohypermethylation of p14 in combination with CADM1 or DCC as a recurrence‐related prognostic indicator in stage I esophageal squamous cell carcinoma

BACKGROUND:

The objective of this study was to discover molecular biomarkers associated with the recurrence of esophageal squamous cell carcinoma (ESCC).

METHODS:

The authors retrospectively analyzed the hypermethylation status of 11 genes using methylation‐specific polymerase chain reaction (PCR) and the expression of epidermal growth factor receptor (EGFR), O‐6 methylguanine‐DNA methyltransferase (MGMT), tumor protein 53 (p53), and transforming growth factor β (TGFβ) using immunohistochemistry in 329 formalin‐fixed, paraffin‐embedded ESCCs.

RESULTS:

Recurrence was identified in 151 of 329 ESCCs (46%) at a median follow‐up of 4.5 years. The recurrence was associated with hypermethylation of the genes cell adhesion molecule 1 (CADM1) (P = .003), deleted in colon carcinoma (DCC) (P = .04), or cyclin‐dependent kinase inhibitor 2A (p14) (P = .02) in patients with stage I ESCC. Thirty‐six of 37 Stage I ESCCs (97%) that had cohypermethylation of at least 2 of the 3 genes had hypermethylation of p14 plus either CADM1 or DCC or both CADM1 and DCC. The 5‐year recurrence‐free survival (RFS) rates were 93% in patients who had stage I disease without hypermethylation of the 3 genes and 56% in those who had cohypermethylation of p14 in combination with CADM1 and/or DCC. Patients who had stage I ESCC with cohypermethylation of p14 in combination with DCC and/or CADM1 had 7.13 times (95% confidence interval, 1.61‐31.64 times; P = .009) poorer RFS compared with those who had no hypermethylation of the 3 genes after adjusting confounding factors. Hypermethylation of the other 8 genes and altered expression of 4 proteins were not associated with recurrence across pathologic stages.

CONCLUSIONS:

The current results suggested that cohypermethylation of p14 in combination with DCC and/or CADM1 may be an independent prognostic factor for recurrence in patients with stage I ESCC. Cancer 2013. © 2013 American Cancer Society.     

Promoter hypermethylation profile of tumor-associated genes p16, p15, hMLH1, MGMT and E-cadherin in oral squamous cell carcinoma

Aberrant promoter hypermethylation of tumor-associated genes leading to their inactivation is a common event in many cancer types. Using a sensitive restriction-multiplex PCR method, we studied the promoter hypermethylation profile of the p16, p15, hMLH1, MGMT and E-cad genes in oral squamous cell carcinoma (OSCC) of Indians. We analyzed a total of 51 samples for the p15 tumor-suppressor gene and 99 samples for each of the remaining genes. Our studies indicate an incidence of promoter hypermethylation of 23% each for p16 and p15, 8% for hMLH1, 41% for MGMT and 35% for E-cad. We observed aberrant hypermethylation of the promoter region of at least 1 of these genes in 74.5% of cases (n = 51) for which all the 5 genes were studied. Abnormal methylation was detected in tumors irrespective of stage and location in the oral cavity, whereas no abnormal methylation was detectable in normal oral squamous tissues obtained from 25 OSCC patients. Detection of aberrant hypermethylation patterns of cancer-associated genes listed above is therefore suitable for diagnosis of OSCC in individuals at high risk for this disease.     

Frequent but borderline methylation of<Emphasis Type="Italic"> p16</Emphasis><Superscript>INK4a</Superscript> and<Emphasis Type="Italic"> TIMP3</Emphasis> in medulloblastoma and sPNET revealed by quantitative analyses

Certain risk groups among tumors of the central nervous system (CNS) in children take an almost inevitably fatal course. The elucidation of molecular mechanisms offers hope for improved therapy. Aberrant methylation is common in malignant brain tumors of childhood and may have implications for stratification and therapy. Methylation of p16 ^INK4A, p14 ^ARF, TIMP3, CDH1, p15 ^INK4B and DAPK1 in medulloblastoma (MB) and ependymoma has been discussed controversially in the literature. DUTT1 and SOCS1 have not previously been analyzed. We examined methylation in MB, sPNET and ependymoma using methylation-specific PCR (MSP), quantitative Combined Bisulfite Restriction Analysis (COBRA) and direct and clone sequencing of bisulfite PCR products. We detected methylation of p16 ^INK4A (17/43), p14 ^ARF (11/42) and TIMP3 (9/44) in MB and others by MSP. CDH1 was not only methylated in MB (31/41), but also in normal controls. Evaluation of MSP results by quantitative COBRA and sequencing yielded methylation between the detection limits of COBRA (1%) and MSP (0.1%). Only p16 ^INK4A and TIMP3 were methylated consistently in medulloblastomas (p16 ^INK4A 14%, TIMP3 11%) and p16 ^INK4A also in anaplastic ependymomas (1/4 tumors). Methylation ranged from 1–5%. Evaluation of methylation using MSP has thus to be supplemented by quantitative methods. Our analyses raise the issue of the functional significance of low level methylation, which may disturb the delicate growth factor equilibrium within the cell. Therapeutic and diagnostic implications urge into depth analyses of methylation as a mechanism, which might fill some of the gaps of our understanding of brain tumor origin.     

Promoter methylation pattern of caspase-8, P16INK4A,MGMT, TIMP-3, and E-cadherin in medulloblastoma

Methylation of promoter regions of CpG-rich sites is an important mechanism for silencing of tumor suppressor genes (TSG). To evaluate the role of tumor suppressor genes caspase-8 (CASP8), TIMP-3, E-cadherin (CDH1), p16^INK4A, and MGMT in medulloblastoma tumorigenesis, 51 medulloblastomas (46 primary tumor specimens, 5 cell lines) were screened for methylation of promoter linked CpG-islands. For CASP8, we examined the 5′ UTR region that has been shown to be associated with expression of CASP8. As detected by methylation specific PCR, methylation rate was low for TIMP-3 (3% of tumor samples; 1/5 cell lines), for MGMT (0% of tumor samples; 1/5 cell lines), for p16^INK4A (2% of tumor samples; 2/5 cell lines) and for CDH1 (8% of tumor samples; 1/4 cell lines). CASP8, however, was methylated in 90% of tumor samples and 4/5 cell lines examined. Screening other tumor entities for CASP8 methylation, we found a similarly high level in 6 neuroblastoma cell lines in contrast to 5 osteosarcoma-, 4 Ewing’s sarcoma-and 6 non-embryonic tumor cell lines without any increased promoter methylation. From our results we conclude that methylation of the CASP8 5′ UTR region may play a role in inactivation of CASP8 in neural crest tumors.     

p16INK4A immunohistochemical staining and predictive value for progression of cervical intraepithelial neoplasia grade 1: A prospective study in China

p16^INK4A is strongly expressed in tissues diagnosed as cervical intraepithelial neoplasia (CIN) and cancer in women infected with human papillomavirus (HPV), but few prospective studies have evaluated p16^INK4A as a marker for the risk of low‐grade CIN (CIN1) progression. We investigated the prevalence of p16^INK4A immunostaining by CIN grade and whether overexpression of p16^INK4A in CIN1 predicts future risk for high‐grade CIN in Chinese women. 6,557 Chinese women aged 30–49 years were screened from 2003 to 2005 using cytology and carcinogenic HPV test. Colposcopy was performed on women with any abnormal result. p16^INK4A Immunostaining was performed on biopsies from all women with CIN1, as well as randomly selected women with normal or CIN grade 2 and worse (CIN2+) biopsies. Women with CIN1 were followed up without treatment. Colposcopy was performed on all untreated women at a 2‐year interval. The prevalence of p16^INK4A staining was 2.7%, 42.7%, 75.5%, 79.6% and 100% among women with normal, CIN1, 2, 3 and cancer biopsies, respectively (p < 0.001). HPV positivity was strongly associated with p16^INK4A staining [odds ratios (OR) = 12.8; 95% confidence intervals (CI): 5.2–31.6]. p16^INK4A staining of CIN1 biopsies at baseline was associated with an increased risk of finding high‐grade CIN over 2 years of follow‐up (OR = 1.43; 95% CI: 0.52–3.91). The two‐year cumulative incidence of CIN2+ for p16^INK4A positive women was higher at 10.71% than for p16^INK4A negative women at 1.30% (crude RR = 8.25, 95% CI: 1.02–66.62). p16^INK4A overexpression is strongly associated with grade of CIN and risk of progression to high‐grade CIN in women with low‐grade lesions.     

Role of mucosal high‐risk human papillomavirus types in head and neck cancers in central India

Mucosal high‐risk (HR) human papillomaviruses (HPV) cause a subset of head and neck cancers (HNC). The HPV‐attributable fraction of HNC varies substantially between countries. Although HNC has a very high incidence in the Indian subcontinent, information on the contribution of HPV infection is limited. Here, we evaluated the HPV‐attributable fraction in HNC (N = 364) collected in a central region of India. HNC from three different anatomical subsites were included, namely, oral cavity (n = 252), oropharynx (n = 53) and hypopharynx/larynx (n = 59). In this retrospective study, HPV‐driven HNC were defined by presence of both viral DNA and RNA. Overexpression of p16^INK4a was also evaluated. HR‐HPV DNA was detected in 13.7% of the cases; however, only 2.7% were positive for both HPV DNA and RNA. The highest percentage of HPV DNA/RNA double positivity was found in oropharynx (9.4%), followed by larynx (1.7%) and oral cavity (1.6%) (p = 0.02). More than half of HPV DNA/RNA‐positive cases were p16^INK4a‐negative, while a considerable number of HPV RNA‐negative cases were p16^INK4a‐positive (17.9%). HPV16 was the major type associated with HNC (60.0%), although cases positive for HPV18, 35 and 56 were also detected. Our data indicate that the proportion and types of mucosal HR‐HPV associated with HNC in this central Indian region differ from those in other (developed) parts of the world. This may be explained by differences in smoking and/or sexual behaviour compared with North America and northern Europe. Moreover, we show that p16^INK4a staining appeared not to be a good surrogate marker of HPV transformation in the Indian HNC cases.