Distinctive Features of Advancing Breast Cancer Cells and Interactions with Surrounding Stroma Observed Under the Scanning Electron Microscope

Breast cancer cells undergo transformation when they spread into surrounding tissues. Studies have shownthat cancer cells undergo surface alterations and interact with the surrounding microenvironment during theinvasion process. The aim of the present study was to analyse these cancer cell surface alterations and interactionsof cancer cells and stroma. Twenty 1-methyl-1-nitrosourea-induced breast cancer samples taken from five ratswere fixed in McDowell-Trump fixative and then washed in 0.1 M phosphate buffer. The samples were thentreated with osmium tetroxide before being washed in distilled water and subsequently dehydrated throughgraded ethanols. The dehydrated samples were immersed in hexamethyldisilazane (HMDS), then followingremoval of excess HMDS, the samples were air dried at room temperature in a dessicator. The dried sampleswere mounted onto specimen stubs and coated with gold coater before being viewed under a scanning electronmicroscope. We detected the presence of membrane ruffles on the surface of cancer cells and the formation ofunique surface membrane protrusions to enhance movement and adhesion to the surrounding stroma duringthe process of invasion. Advancing cancer cells demonstrated formation of lamellipodia and invadopodia. Thestroma at the advancing edge was desmoplastic with many collagen fibres laid down near the cancer cells. Ourdata suggest that all of these abnormalities could act as hallmarks of invasiveness for breast cancer.