Integrin profile of circulating tumour cells in breast cancer patients

Abstract

Background. Integrins, as adhesion molecules, play a key role in the interaction of cells with the basal membrane and intercellular matrix. Numerous studies demonstrate evidence of increased expression of integrins on tumor cells in different types of cancer. Thus, β3 and αV integrins are associated with stem-like features of tumor cells, and β4 integrin as α6β4 heterodimer provides anchorage-independent survival of malignant mammary epithelial cells. However, all the described functions of integrins have been investigated exclusively on primary tumor cells. The functional significance and expression pattern of integrins on circulating tumor cells (CTCs) remains unclear. The aim of the study was to evaluate the β3, β4 and αvβ5 integrin expression on CTCs and its association with molecular subtype, stage and lymph node metastasis in breast cancer patients Material and Methods. The study included 22 patients with T1–4N0–3M0 invasive ductal breast carcinoma. Venous blood was taken from patients without neoadjuvant chemotherapy (group 1) and after neoadjuvant chemotherapy (group 2) in the volume of 12 ml into vacuum tubes with EDTA. The expression of CTC integrins including stemness features CD44/CD24, CD133 and ALDH1, and epithelial-mesenchymal transition (EMT) (N-cadherin) was evaluated by flow cytometry. Results. CTCs with β3+β4-αvβ5- and β3-β4+αvβ5+ phenotypes and stemness properties were associated with larger tumor size (T4) in breast cancer patients. The β3 integrin expression was associated with more aggressive molecular subtypes of breast cancer. Administration of neoadjuvant chemotherapy did not affect the expression pattern of β3, β4 and αvβ5 integrins in CTCs. Conclusion. In breast cancer, most CTCs expressed β3, β4 and αvβ5 integrins despite the lack of attachment to the basal membrane and intercellular matrix. The expression of the above integrins on CTCs was associated with breast cancer molecular subtype, stage and lymph node metastasis, and therefore its evaluation can be considered as one of the objectives of liquid biopsy study.

Keywords

• breast cancer
• circulating tumor cells
• integrins
• neoadjuvant chemotherapy