Identification of intravasation sites for metastatic biomarker development

Metastatic breast cancer is a leading cause of mortality in women worldwide. The key to metastatic progression is the ability of cancer cells to breach the endothelial basement membrane and enter the vasculature. It has long been believed that the process of intravasation is preceded by local invasion, and yet, several studies have detected circulating tumour cells at earlier disease stages. This suggests that intravasation may occur without detectable invasion into the surrounding microenvironment. To investigate this, we developed a vascular labelling strategy that incorporates three components to collectively mark sites of intravasation, allowing for detailed analysis of their molecular and structural characteristics. In this thesis, we validate first the surface expression of two fluorophores, EGFP and mT2. Following surface expression, we show that a recombinant protein moiety binds specifically to EGFP expressed on the surface. Building on this specific cell-surface interaction, we bound the targeting moiety to a large molecular weight dextran that is retained in the vasculature, coupled with fluorescent streptavidin for intravital imaging. Combining these components, we were successful in performing intravital imaging to identify differentially labelled blood vessels, indicating possible intravasation sites. Future work will involve confirmation of the specificity of the labelling approach for sites of intravasation, followed by laser capture microdissection coupled to proteomics for molecular assessment of the changes at these sites of breached vasculature. Importantly, by working with biobanks and clinical collaborators, identified markers of intravasation will be validated against large clinical cohorts to provide actionable therapeutic targets and novel biomarkers for disease stratification, with the central goal of improving patient outcomes from this work.

Grantor dc:publisher

Helsingin yliopisto

Year dc:date.issued

2026

Author dc:creator

• Yassine, Hassan

• breast cancer
• metastasis
• intravasation
• vasculature
• FLIM

Statement dc:rights

• In Copyright 1.0

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/10138/633161

OAI identifier oai:identifier

oai:helda.helsinki.fi:10138/633161