Hypermethylation of RASSF1A in human and rhesus placentas.

The pseudomalignant nature of the placenta prompted us to search for tumor suppressor gene hypermethylation, a phenomenon widely reported in cancer, in the human placenta. Nine tumor suppressor genes were studied. Hypermethylation of the Ras association domain family 1 A (RASSF1A) gene was found in human placentas from all three trimesters of pregnancy but was absent in other fetal tissues.

Qualitative and quantitative polymerase chain reaction-based methods for DNA methylation analyses.

DNA methylation can be analyzed easily by qualitative or quantitative polymerase chain reaction (PCR)-based methods, including methylation-specific PCR (MSP), bisulfite sequencing, methylation-sensitive restriction enzyme PCR, combined bisulfite restriction analysis (COBRA), methylation-sensitive single nucleotide primer extension (Ms-SNuPE), and quantitative real-time MSP. MSP, which couples the bisulfite modification of DNA and PCR, is fast, highly sensitive, specific, and widely applied for DNA methylation analyses. Bisulfite modification converts unmethylated cytosine to uracil, whereas methylcytosine remains unmodified.

Ubiquitous aberrant RASSF1A promoter methylation in childhood neoplasia.

Purpose And Experimental Design: The role of RASSF1A has been elucidated recently in regulating apoptosis and cell cycle progression by inhibiting cyclin D1 accumulation. Aberrant RASSF1A promoter methylation has been found frequently in multiple adult cancer types. Using methylation-specific PCR and reverse transcription-PCR, we investigated epigenetic deregulation of RASSF1A in primary tumors, adjacent nontumor tissues, secondary metastases, peripheral blood cells, and plasma samples from children with 18 different cancer types, in association with their clinicopathologic features.

Tumor-derived aberrant methylation in plasma of invasive ductal breast cancer patients: clinical implications.

Progressive p16 methylation has been associated with metastasis and invasive phenotypes in many cancers. Loss of E-cadherin (CDH1) function contributes to breast cancer progression by promoting cell proliferation, invasion and metastasis. Using methylation-specific PCR, aberrant hypermethylation of p16 and CDH1 in tumor and plasma was analyzed and correlated with levels of serum protein markers, carcinoembryonic antigen (CEA) and carcinoma antigen 15-3 (CA15.

Quantitative analysis of tumor-derived methylated p16INK4a sequences in plasma, serum, and blood cells of hepatocellular carcinoma patients.

Purpose And Experimental Design: Using real-time quantitative methylation-specific PCR (RTQ-MSP), we quantified methylated p16INK4a sequences and determined the fractional concentrations of circulating tumor DNA in plasma, serum, and peripheral blood cells collected preoperatively, intraoperatively, and postoperatively from 49 patients with hepatocellular carcinoma (HCC).

Results: RTQ-MSP was sufficiently sensitive to detect down to 10 genome-equivalents of methylated p16INK4a sequences. Quantitative MSP data were expressed in terms of the methylation index, which was the percentage of bisulfite converted unmethylated and methylated p16INK4a sequences that consisted of methylated p16INK4a sequences.

Transcriptional profiling of circulating tumor cells: quantification and cancer progression (Review).

Circulating tumor cells in peripheral blood have been demonstrated to reflect the biological characteristics of tumors including the potential for metastasis development and tumor recurrence. A number of mRNA markers may feasibly enable the detection of circulating tumor cells from virtually all patients with different cancer types. Of clinical relevance, quantification of circulating tumor cell mRNAs in cancer patients may prove valuable for monitoring disease progression and patients' response to treatment, and assessing the risk for metastasis or recurrence.

New markers for cancer detection.

Circulating tumor nucleic acids in blood have been demonstrated to reflect the biologic characteristics of tumors. During tumor progression, aberrant DNA methylation can lead to transcriptional silencing of tumor suppressor genes, DNA repair genes, and metastasis-inhibitor genes. Hypermethylation of multiple genes, detectable in the blood of cancer patients, has demonstrated increasing promise as a specific and sensitive molecular marker for detecting and monitoring cancer.