Variations in Cell Surfaces of Estrogen Treated Breast Cancer Cells Detected by A Combined Instrument for Far-Field and Near-Field Microscopy

The response of single breast cancer cells (cell line T‐47D) to 17β‐estradiol (E(2)) under different concentrations was studied by using an instrument that allows to combine far‐field light microscopy with high resolution scanning near‐field (AFM/SNOM) microscopy on the same cell. Different concentrations of E(2) induce clearly different effects as well on cellular shape (in classical bright‐field imaging) as on surface topography (atomic force imaging) and absorbance (near‐field light transmission imaging). The differences range from a polygonal shape at zero via a roughly spherical shape at physiological up to a spindle‐like shape at un‐physiologically high concentrations. The surface topography of untreated control cells was found to be regular and smooth with small overall height modulations. At physiological E(2) concentrations the surfaces became increasingly jagged as detected by an increase in membrane height. After application of the un‐physiological high E(2) concentration the cell surface structures appeared to be smoother again with an irregular fine structure. The general behaviour of dose dependent differences was also found in the near‐field light transmission images. In order to quantify the treatment effects, line scans through the normalised topography images were drawn and a rate of co‐localisation between high topography and high transmission areas was calculated. The cell biological aspects of these observations are, so far, not studied in detail but measurements on single cells offer new perspectives to be empirically used in diagnosis and therapy control of breast cancers.