Accuracy of self-collected vaginal dry swabs using the Xpert human papillomavirus assay.

BACKGROUND: Polymerase chain reaction-based Xpert human papillomavirus (HPV) assay is a rapid test that detects high-risk HPV (hrHPV) infection. This point-of-care test is usually performed by collecting a cervical specimen in a vial of PreservCyt® transport medium. We compared HPV test positivity and accuracy between self-collected sample with a dry swab (s-DRY) versus physician-collected cervical sampling using a broom like brush and immediate immersion in PreservCyt (dr-WET). METHODS: In this cross-sectional study, we recruited 150 women ≥ 18 years old attending the colposcopy clinic in the University Hospital of Geneva. Each participant first self-collected a vaginal sample using a dry swab and then the physician collected a cervical specimen in PreservCyt. HPV analysis was performed with Xpert. Part of the PreservCyt-collected sample was used for hrHPV detection with the cobas® HPV test. HPV test positivity and performance of the two collection methods was compared. RESULTS: HPV positivity was 49.1% for s-DRY, 41.8% for dr-WET and 46.2% for cobas. Good agreement was found between s-DRY and dr-WET samples (kappa±Standard error (SE) = 0.64±0.09,), particularly for low-grade squamous intraepithelial lesions (LSIL+) (kappa±SE = 0.80±0.17). Excellent agreement was found between the two samples for HPV16 detection in general (kappa±SE = 0.91±0.09) and among LSIL+ lesions (kappa±SE = 1.00±0.17). Sensitivities and specificities were, respectively, 84.2% and 47.1%(s-DRY), 73.1% and 58.7%. (dr-WET) and 77.8% and 45.7% (cobas) for CIN2+ detection. The median delay between sampling and HPV analysis was 7 days for the Xpert HPV assay and 19 days for cobas. There were 36 (24.0%) invalid results among s-DRY samples and 4 (2.7%) among dr-WET (p = 0.001). Invalid results happened due to the long interval between collection and analysis. CONCLUSION: Self-collected vaginal dry swabs are a valid alternative to collecting cervical samples in PreservCyt solution for HPV testing with the Xpert HPV assay. IMPACT: HPV self-collection with dry cotton swabs might assist in the implementation of an effective screening strategy in developing countries. TRIAL REGISTRATION: International Standard Randomized Controlled Trial Number Registry ISRCTN83050913.

DNA methylation profiling of esophageal adenocarcinoma using Methylation Ligation-dependent Macroarray (MLM).

Most types of cancer cells are characterized by aberrant methylation of promoter genes. In this study, we described a rapid, reproducible, and relatively inexpensive approach allowing the detection of multiple human methylated promoter genes from many tissue samples, without the need of bisulfite conversion. The Methylation Ligation-dependent Macroarray (MLM), an array-based analysis, was designed in order to measure methylation levels of 58 genes previously described as putative biomarkers of cancer. The performance of the design was proven by screening the methylation profile of DNA from esophageal cell lines, as well as microdissected formalin-fixed and paraffin-embedded (FFPE) tissues from esophageal adenocarcinoma (EAC). Using the MLM approach, we identified 32 (55%) hypermethylated promoters in EAC, and not or rarely methylated in normal tissues. Among them, 21promoters were found aberrantly methylated in more than half of tumors. Moreover, seven of them (ADAMTS18, APC, DKK2, FOXL2, GPX3, TIMP3 and WIF1) were found aberrantly methylated in all or almost all the tumor samples, suggesting an important role for these genes in EAC. In addition, dysregulation of the Wnt pathway with hypermethylation of several Wnt antagonist genes was frequently observed. MLM revealed a homogeneous pattern of methylation for a majority of tumors which were associated with an advanced stage at presentation and a poor prognosis. Interestingly, the few tumors presenting less methylation changes had a lower pathological stage. In conclusion, this study demonstrated the feasibility and accuracy of MLM for DNA methylation profiling of FFPE tissue samples.

Use of swabs for dry collection of self-samples to detect human papillomavirus among Malagasy women.

BACKGROUND: Most women in developing countries have never attended cervical screening programmes and often little information exists on type-specific human papillomavirus (HPV) prevalence among these populations. Self-sampling for HPV testing (self-HPV) using a dry swab may be useful for establishing a screening program and evaluating HPV prevalence. Our aim was to evaluate self-HPV using a dry swab stored at room temperature. METHODS: This community-based study in Madagascar consisted of 449 women aged 30-65. Eligible women were provided a dry swab to perform self-HPV. HPV analysis was accomplished by two different real-time PCR tests using the same extracted DNA from the samples. RESULTS: Overall, 52 (11.6 %) specimens were invalid for HPV detection. The delay between sampling and laboratory processing of DNA extraction considerably increased invalid results. Overall HPV prevalence of 14 hrHPV types detected by the two PCR tests was found to be 38.2 % (n = 152). Distribution of 19 hrHPV and 9 low-risk HPV (lrHPV) types revealed most frequently 53 and 68 among hrHPV and HPV 54, HPV 70 and HPV 42 among lrHPV. Agreement between the two PCR methods for any of the 14 high-risk HPV (hrHPV) strains detected was 89.9 % (kappa = 0.77, 95 % CI: 0.71-0.84). In 385 (85.7 %) samples the DNA load of ß-globin demonstrated a signal with medium or high level copies. Conversely, in 28 (60.9 %) invalid samples the signal was undetectable. The HPV-DNA load signal was predominantly of intermediate level (58.5 %, n = 218). CONCLUSIONS: Self-HPV using a dry swab stored at room temperature could be a useful method for HPV screening and for conducting population-based surveys on HPV prevalence in resource-poor settings.

Cervical cancer screening in sub-Saharan Africa: a randomized trial of VIA versus cytology for triage of HPV-positive women.

Developing countries are interested in using human papillomavirus (HPV) testing as a primary screening test for cervical cancer prevention programs. The low specificity of the HPV assay requires triage testing of HPV-positive women. The aim of the study is to compare visual inspection with acetic acid (VIA) and cytology as triage testing methods in HPV-positive women to detect cervical intraepithelial neoplasia or Grade 2 or higher (CIN2+). The study was conducted in two Cameroonian towns (Yaoundé and Edea) and included 846 eligible women aged 25 to 65 years. All participants performed self-HPV testing. HPV-positive women (n = 259) were randomly assigned to be tested either by VIA (VIA group) or cytology (cytology group). HPV-positive women had both cervical biopsy and endocervical curettage to detect biopsy-confirmed CIN2+. All statistical tests were two-sided. The prevalence of HPV was 38.5%, and the mean age of HPV-positive women was 41.5 ± 10.1 years. One hundred ninety-eight women (97 in the VIA group and 99 in the cytology) were randomly assigned to one of the two testing arms. The sensitivity of VIA was 25.0% (95% CI, 7.1-59.1%), and the sensitivity of cytology was 90.0% (59.6-98.2%). The specificity was 74.2% (95% CI, 64.2-82.1%) for VIA and 85.2% (76.3-91.2%) for cytology. ROC area for cytology was 0.910 against the 0.496 area for VIA. In this trial, VIA was inferior to cytology as a triage test among HPV-positive women. Further investigations are needed to determine the optimal triage method for HPV-positive women.

Methylation of the hTERT promoter: a novel cancer biomarker for leptomeningeal metastasis detection in cerebrospinal fluids.

PURPOSE: The diagnosis of leptomeningeal metastases is usually confirmed by the finding of malignant cells by cytologic examination in the cerebrospinal fluid (CSF). More sensitive and specific cancer biomarkers may improve the detection of tumor cells in the CSF. Promoter methylation of the human telomerase reverse transcriptase (hTERT) gene characterizes most cancer cells. The aim of this study was to develop a sensitive method to detect hTERT methylation and to explore its use as a cancer biomarker in CSF. EXPERIMENTAL DESIGN: In 77 CSF specimens from 67 patients, hTERT promoter methylation was evaluated using real-time methylation-sensitive high-resolution melting (MS-HRM) and real-time TaqMan PCR and MS-HRM in a single-tube assay. RESULTS: Real-time MS-HRM assay was able to detect down to 1% hTERT-methylated DNA in a background of unmethylated DNA. PCR products were obtained from 90% (69/77) of CSF samples. No false positive hTERT was detected in the 21 non-neoplastic control cases, given to the method a specificity of 100%. The sensitivity of the real-time MS-HRM compared with the cytologic gold standard analysis was of 92% (11/12). Twenty-six CSFs from 22 patients with an hTERT-methylated primary tumor showed cytologic results suspicious for malignancy; in 17 (65%) of them, a diagnosis of leptomeningeal metastases could be confirmed by the hTERT methylation test. CONCLUSION: The hTERT real-time MS-HRM approach is fast, specific, sensitive, and could therefore become a valuable tool for diagnosis of leptomeningeal metastases as an adjunct to the traditional examination of CSF.

A comprehensive characterization of genome-wide copy number aberrations in colorectal cancer reveals novel oncogenes and patterns of alterations.

To develop a comprehensive overview of copy number aberrations (CNAs) in stage-II/III colorectal cancer (CRC), we characterized 302 tumors from the PETACC-3 clinical trial. Microsatellite-stable (MSS) samples (n = 269) had 66 minimal common CNA regions, with frequent gains on 20 q (72.5%), 7 (41.8%), 8 q (33.1%) and 13 q (51.0%) and losses on 18 (58.6%), 4 q (26%) and 21 q (21.6%). MSS tumors have significantly more CNAs than microsatellite-instable (MSI) tumors: within the MSI tumors a novel deletion of the tumor suppressor WWOX at 16 q23.1 was identified (p<0.01). Focal aberrations identified by the GISTIC method confirmed amplifications of oncogenes including EGFR, ERBB2, CCND1, MET, and MYC, and deletions of tumor suppressors including TP53, APC, and SMAD4, and gene expression was highly concordant with copy number aberration for these genes. Novel amplicons included putative oncogenes such as WNK1 and HNF4A, which also showed high concordance between copy number and expression. Survival analysis associated a specific patient segment featured by chromosome 20 q gains to an improved overall survival, which might be due to higher expression of genes such as EEF1B2 and PTK6. The CNA clustering also grouped tumors characterized by a poor prognosis BRAF-mutant-like signature derived from mRNA data from this cohort. We further revealed non-random correlation between CNAs among unlinked loci, including positive correlation between 20 q gain and 8 q gain, and 20 q gain and chromosome 18 loss, consistent with co-selection of these CNAs. These results reinforce the non-random nature of somatic CNAs in stage-II/III CRC and highlight loci and genes that may play an important role in driving the development and outcome of this disease.

hTERT methylation is necessary but not sufficient for telomerase activity in colorectal cells.

Colorectal cancers exhibit a high telomerase activity, usually correlated with the hypermethylation of the promoter of its hTERT catalytic subunit. Although telomerase is not expressed in normal tissue, certain proliferative somatic cells such as intestinal crypt cells have demonstrated telomerase activity. The aim of this study was to determine whether a correlation exists between telomerase activity, levels of hTERT methylation and telomere length in tumoral and normal colorectal tissues. Tumor, transitional and normal tissues were obtained from 11 patients with a colorectal cancer. After bisulfite modification of genomic DNA, hTERT promoter methylation was analyzed by methylation-sensitive single-strand conformation analysis (MS-SSCA). Telomerase activity and telomere length were measured by a fluorescent-telomeric repeat amplification protocol assay and by Southern blotting, respectively. A significant increase of hTERT methylation and telomerase activity, and a reduction of the mean telomere length were observed in the tumor tissues compared to the transitional and normal mucosa. In the transitional and normal mucosa, telomerase activity was significantly lower than that in tumor tissues, even with high levels of hTERT methylation. Nevertheless, hTERT promoter methylation was not linearly correlated to telomerase activity. These data indicate that hTERT promoter methylation is a necessary event for hTERT expression, as is telomerase activity. However, methylation is not sufficient for hTERT activation, particularly in normal colorectal cells.

PAX5 activates the transcription of the human telomerase reverse transcriptase gene in B cells.

Telomerase is an RNA-dependent DNA polymerase that synthesizes telomeric DNA. Its activity is not detectable in most somatic cells but it is reactivated during tumorigenesis. In most cancers, the combination of hTERT hypermethylation and hypomethylation of a short promoter region is permissive for low-level hTERT transcription. Activated and malignant lymphocytes express high telomerase activity, through a mechanism that seems methylation-independent. The aim of this study was to determine which mechanism is involved in the enhanced expression of hTERT in lymphoid cells. Our data confirm that in B cells, some T cell lymphomas and non-neoplastic lymph nodes, the hTERT promoter is unmethylated. Binding sites for the B cell-specific transcription factor PAX5 were identified downstream of the ATG translational start site through EMSA and ChIP experiments. ChIP assays indicated that the transcriptional activation of hTERT by PAX5 does not involve repression of CTCF binding. In a B cell lymphoma cell line, siRNA-induced knockdown of PAX5 expression repressed hTERT transcription. Moreover, ectopic expression of PAX5 in a telomerase-negative normal fibroblast cell line was found to be sufficient to activate hTERT expression. These data show that activation of hTERT in telomerase-positive B cells is due to a methylation-independent mechanism in which PAX5 plays an important role.

Specific association between the methyl-CpG-binding domain protein 2 and the hypermethylated region of the human telomerase reverse transcriptase promoter in cancer cells.

Human telomerase reverse transcriptase (hTERT) is expressed in most cancer cells. Paradoxically, its promoter is embedded in a hypermethylated CpG island. A short region escapes to this alteration, allowing a basal level of transcription. However, the methylation of adjacent regions may play a role in the maintenance of low hTERT expression. It is now well established that methyl-CpG binding domain proteins mediate the transcriptional silencing of hypermethylated genes. The potential involvement of these proteins in the control of hTERT expression was firstly investigated in HeLa cells. Chromatin immunoprecipitation assays showed that only methyl-CpG-binding domain protein 2 (MBD2) associated the hypermethylated hTERT promoter. In MBD2 knockdown HeLa cells, constitutively depleted in MBD2, neither methyl CpG binding protein 2 (MeCP2) nor MBD1 acted as substitutes for MBD2. MBD2 depletion by transient or constitutive RNA interference led to an upregulation of hTERT transcription that can be downregulated by expressing mouse Mbd2 protein. Our results indicate that MBD2 is specifically and directly involved in the transcriptional repression of hTERT in HeLa cells. This specific transcriptional repression was also observed in breast, liver and neuroblastoma cancer cell lines. Thus, MBD2 seems to be a general repressor of hTERT in hTERT-methylated telomerase-positive cells.