Dataset Information

The potential of liquid biopsy for detection of the KIAA1549-BRAF fusion in circulating tumor DNA from children with pilocytic astrocytoma.

ABSTRACT:

Background

Low-grade gliomas (LGGs) represent children's most prevalent central nervous system tumor, necessitating molecular profiling to diagnose and determine the most suitable treatment. Developing highly sensitive screening techniques for liquid biopsy samples is particularly beneficial, as it enables the early detection and molecular characterization of tumors with minimally invasive samples.

Methods

We examined CSF and plasma samples from patients with pilocytic astrocytoma (PA) using custom multiplexed droplet digital polymerase chain reaction (ddPCR) assays based on whole genome sequencing data. These assays included a screening test to analyze BRAF duplication and a targeted assay for the detection of patient-specific KIAA1549::BRAF fusion junction sequences or single nucleotide variants.

Results

Our findings revealed that 5 out of 13 individual cerebrospinal fluid (CSF) samples tested positive for circulating tumor DNA (ctDNA). Among these cases, 3 exhibited the KIAA1549::BRAF fusion, which was detected through copy number variation (CNV) analysis (n = 1) or a fusion-specific probe (n = 2), while 1 case each displayed the BRAF V600E mutation and the FGFR1 N577K mutation. Additionally, a quantitative analysis of cell-free DNA (cfDNA) concentrations in PA CSF samples showed that most cases had low cfDNA levels, below the limit of detection of our assay (<1.9 ng).

Conclusions

While CNV analysis of CSF samples from LGGs still has some limitations, it has the potential to serve as a valuable complementary tool. Furthermore, it can also be multiplexed with other aberrations, for example, to the BRAF V600 test, to provide important insights into the molecular characteristics of LGGs.

SUBMITTER: Krynina O

PROVIDER: S-EPMC10874216 | biostudies-literature | 2024 Jan-Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

The potential of liquid biopsy for detection of the KIAA1549-BRAF fusion in circulating tumor DNA from children with pilocytic astrocytoma.

Krynina Olha O de Ståhl Teresita Díaz TD Jylhä Cecilia C Arthur Cecilia C Giraud Geraldine G Nyman Per P Fritzberg Anders A Sandgren Johanna J Tham Emma E Sandvik Ulrika U

Neuro-oncology advances 20240124 1

<h4>Background</h4>Low-grade gliomas (LGGs) represent children's most prevalent central nervous system tumor, necessitating molecular profiling to diagnose and determine the most suitable treatment. Developing highly sensitive screening techniques for liquid biopsy samples is particularly beneficial, as it enables the early detection and molecular characterization of tumors with minimally invasive samples.<h4>Methods</h4>We examined CSF and plasma samples from patients with pilocytic astrocytoma ...[more]

PMID: 38371226

Similar Datasets

Project description:Microvascular proliferation (MVP), an aberrant vascular structure containing multilayered mitotically active endothelial- and smooth-muscle cells/pericytes, is a histopathological hallmark of glioblastoma multiforme (GBM). Although MVP tends to be associated with high-grade glioma, it has also been detected in WHO grade I pilocytic astrocytoma (PA). However, little is known about the mechanism underlying its formation. Using TP53 point mutations as a marker for tumor-derived cells, we earlier reported that MVP was partially converted from tumor cells via mesenchymal transition. In the current study we used the KIAA1549-BRAF fusion gene as a marker to assess whether MVPs in PA contained tumor-derived cells and/or phenotypically distinct tumor cells expressing vascular markers. cDNA synthesized from frozen tissue of six PA patients operated at our institute was analyzed to detect the KIAA1549-BRAF fusion gene by reverse transcription polymerase chain reaction (RT-PCR) assay. The breakpoint in the fusion gene was identified by long and accurate PCR (LA-PCR) and Sanger sequencing of genomic DNA. Distinct tumor cells and cellular components of MVP were obtained by laser microdissection. For the qualitative and quantitative detection of the KIAA1549-BRAF fusion gene we performed genomic and digital PCR assays. Fluorescence in situ hybridization (FISH) was used to assess gene fusion in cellular components of MVP. Samples from three PA patients harbored the KIAA1549 exon 15, BRAF exon 9 fusion gene. In two patient samples with abundant MVP, RT-PCR assay detected strong bands arising from the KIAA1549-BRAF fusion gene in both tumor cells and cellular components of MVP. Digital PCR showed that vis-à-vis tumor tissue, its relative expression in cellular components of MVP was 42% in one- and 76% in another sample. FISH revealed amplified signals in both tumor cells and cellular components of MVP indicative of tandem duplication. Our findings suggest that in patients with PA, some cellular components of MVP contained tumor derived cell and/or phenotypically distinct tumor cells expressing vascular markers.

Project description:Pilocytic astrocytoma (PA) is the most frequent pediatric brain tumor. Activation of the MAPK pathway is well established as the oncogenic driver of the disease. It is most frequently caused by KIAA1549:BRAF fusions, and leads to oncogene induced senescence (OIS). OIS is thought to be a major reason for growth arrest of PA cells in vitro and in vivo, preventing establishment of PA cultures. Hence, valid preclinical models are currently very limited, but preclinical testing of new compounds is urgently needed. We transduced the PA short-term culture DKFZ-BT66 derived from the PA of a 2-year old patient with a doxycycline-inducible system coding for Simian Vacuolating Virus 40 Large T Antigen (SV40-TAg). SV40-TAg inhibits TP53/CDKN1A and CDKN2A/RB1, two pathways critical for OIS induction and maintenance. DNA methylation array and KIAA1549:BRAF fusion analysis confirmed pilocytic astrocytoma identity of DKFZ-BT66 cells after establishment. Readouts were analyzed in proliferating as well as senescent states, including cell counts, viability, cell cycle analysis, expression of SV40-Tag, CDKN2A (p16), CDKN1A (p21), and TP53 (p53) protein, and gene-expression profiling. Selected MAPK inhibitors (MAPKi) including clinically available MEK inhibitors (MEKi) were tested in vitro. Expression of SV40-TAg enabled the cells to bypass OIS and to resume proliferation with a mean doubling time of 45h allowing for propagation and long-term culture. Withdrawal of doxycycline led to an immediate decrease of SV40-TAg expression, appearance of senescent morphology, upregulation of CDKI proteins and a subsequent G1 growth arrest in line with the re-induction of senescence. DKFZ-BT66 cells still underwent replicative senescence that was overcome by TERT expression. Testing of a set of MAPKi revealed differential responses in DKFZ-BT66. MEKi efficiently inhibited MAPK signaling at clinically achievable concentrations, while BRAF V600E- and RAF Type II inhibitors showed paradoxical activation. Taken together, we have established the first patient-derived long term expandable PA cell line expressing the KIAA1549:BRAF-fusion suitable for preclinical drug testing.

Dataset Information

The potential of liquid biopsy for detection of the KIAA1549-BRAF fusion in circulating tumor DNA from children with pilocytic astrocytoma.

Background

Methods

Results

Conclusions

Publications

The potential of liquid biopsy for detection of the KIAA1549-BRAF fusion in circulating tumor DNA from children with pilocytic astrocytoma.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets