Abstract

Viscoelastic and other physical properties of cancerous cells are particularly important since cells interact with the extracellular matrix and other cells constantly during malignant proliferation, adhesion, invasion and metastasis process. Atomic force microscope (AFM) has an unparalleled advantage in the measurement of viscoelastic properties of living cells. In this paper, a stress relaxation test using atomic force microscopy was conducted to obtain viscoelastic characteristics of lung cancer cells. The experimental data obtained were well fitted with a special theoretical model which is appropriate to samples with infinite thickness, such as cells. This theoretical model takes into account the thin thickness of the measured sample and the substrate effect generated by a relatively larger indention of AFM probe can be avoided. Two different non-small cell lung cancer cell lines with varying metastatic potential show distinct stress relaxation characteristics. The metastatic NCI-H1299 cells, which are originally isolated from a patient’s lymph node metastases, appeared a lower viscoelastic response compared to the non-metastatic A549 tumorous cells. When cancerous cells release from the primary tumor site, intravasate into lymphatic or blood circulation, and squeeze through a variety of cell gaps to transfer other where, they become easily deformed and thus show lower viscoelastic properties. The emerging insight into these viscoelastic properties may promote the understanding of the underlying mechanism for cancer metastatic and invasive progress.

Keywords: Atomic force microscopy, viscoelastic properties, stress relaxation, thin-layer model, non-small lung cancer cell, metastatic potential.