Germline mutations in CDKN2A result in Familial Atypical Multiple Mole Melanoma Syndrome (FAMMM), which is associated with an increased risk for pancreatic ductal adenocarcinoma and melanoma. CDKN2A is somatically inactivated in multiple neoplasms, raising the possibility that, although the data are not conclusive, germline CDKN2A mutation may also impose an increased risk for other neoplasms. We present a patient with a CDKN2A germline mutation (p16-Leiden mutation) and mosaicism for neurofibromatosis type 2, who presented with a small asymptomatic pancreatic lesion, detected during endoscopic ultrasound screening of the pancreas. After resection, the lesion was found to be a well-differentiated pancreatic neuroendocrine tumor (PanNET). Molecular analysis of the tumor showed somatic loss of the second allele, supporting a causal relation of the PanNET to the underlying FAMMM syndrome. Recent data, showing the association between certain single-nucleotide polymorphisms in the CDKN2A gene and an increased incidence for PanNET, further support a role for germline CDKN2A alterations in PanNET risk. We conclude that PanNETs can be a phenotypic expression of FAMMM syndrome. This can have implications for screening and for the diagnosis of pancreatic neoplasms in carriers of germline CDKN2A mutations.
Abstract Cell-free DNA (cfDNA) in the bloodstream is increasingly gaining attention as a diagnostic tool for the early detection of cancer. Nevertheless, the characteristics and sources of cfDNA fragmentation in the blood remain poorly understood. In this study, we sought to unravel the impact of DNA methylation and gene expression on the naturally occurring genome-wide fragmentation of cfDNA. We performed a comprehensive analysis of plasma samples from 969 individuals, including 182 individuals diagnosed with cancer (pancreatic, colorectal, ovarian, lung and breast cancer). In healthy individual cfDNA fragmentation patterns like DNA motifs at cfDNA fraqgments ends, recurrent cfDNA fragment start sites, cfDNA coverage and cfDNA fragment size were compared to publicly available data on cfDNA methylation and gene expression from myeloid cells. We discovered that the ends of cfDNA fragments, particularly those containing CGs or CCGs, displayed a distinct pattern of enrichment or depletion, respectively, at methylated CpG positions throughout the genome. This phenomenon is consistent with structural models suggesting an increased interaction of CG fragment ends with nucleosomes. cfDNA fragments were more prevalent (up to 3.7 fold) and of larger sizes (up to 4-5 base larger) when derived from regions of methylated CpGs or transcriptional start sites of genes that were not actively expressed. Differences in cfDNA fragmentation reflected specific biological pathways associated with their tissue of origin (like E2f transcription factors and blood cell metabolism genes in cfDNA from healthy individuals). Through analyses of cfDNA from patients with cancer, we identified a connection between tumor-related hypomethylation, increased gene expression, and a global reduction in cfDNA fragment size. This connection may offer an explanation for the generally smaller cfDNA fragments found in individuals with cancer. We found that cancer-specific methylation at CpG sites from pancreatic cancers were associated with widespread changes in cfDNA fragment ends, particularly for patients with pancreatic (test statistic = Welch two sample t-test; p<2.2e-16) and other cancers. These findings establish a direct link between epigenetic modifications and cfDNA fragmentation that may have implications for non-invasive detection of cancer. Citation Format: Michaël Noë, Akshaya V. Annapragada, Zachariah H. Foda, Jamie E. Medina, Dimitrios Mathios, Stephen Cristiano, Christopher Cherry, Daniel C. Bruhm, Noushin Niknafs, Vilmos Adleff, Leonardo Ferreira, Hari Easwaran, Stephen Baylin, Jillian Phallen, Robert B. Scharpf, Victor E. Velculescu. DNA methylation and gene expression as determinants of genome-wide cell-free DNA fragmentation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 974.
Human gonadotropins are glycoprotein hormones with a highly complex structure, which demands the application of sophisticated analytical methodologies to assess their quality. The principal objective of this study was a comparative evaluation of gel electrophoretic techniques and mass spectrometry-based methods for the quality study of the two urinary-derived, highly purified, human menopausal gonadotropin preparations, Menopur 75/75 I. U. and Meriofert 75 I. U. Molecular mass (
