Master’s Project
Sofie Gawinski Lindholm, BSc

I am a master’s student in molecular medicine, currently working on my master’s thesis project. The aim of this study is to investigate whether the analysis of methylation patterns in cell-free DNA (cfDNA) can be used as a biomarker for brain metastases in EGFR-positive non-small cell lung cancer (NSCLC) patients. The hypothesis is based on the theory that cfDNA from the central nervous system (CNS) is not released into the bloodstream in healthy individuals with an intact blood-brain barrier. However, in stage IV NSCLC patients with brain metastases, increased inflammation and cell death in healthy brain tissue, along with a compromised blood-brain barrier, allow cfDNA fragments to diffuse into the circulation. While it has been confirmed that cfDNA from the brain can be detected in blood samples from patients with primary CNS tumors, such as glioblastoma, it remains unexplored if the same is detectable in patients with brain metastases.

In my study, I aim to identify CpG sites that are highly methylated exclusively in brain tissue, but not methylated in any other tissue or cell type. I will perform a differential methylation analysis on human samples from various cell types and tissues to identify CpG sites uniquely highly methylated in brain tissue but not in other human tissues. Furthermore, these selected CpG sites must be non-methylated in lung cancer tissue. From this analysis, I will select 3-5 potential biomarkers for further studies. The first aim is to investigate if cfDNA from brain cells is detectable in the bloodstream upon brain metastases. The method will be validated using purified DNA from plasma of healthy donors as negative controls, while purified DNA from a human glioblastoma cell line and human brain cortex tissue samples will serve as positive controls.

Further studies will be conducted following the validation of the presence of brain-derived cfDNA in plasma. However, the detailed planning of the subsequent steps will be determined based on the outcomes of the initial studies.

My master’s thesis will be submitted in early October and defended in late October 2024.