Monitoring of UVA induced apoptosis in MCF-7 cells by light scattering measurements

Abstract

We report the use of light scattering to monitor the morphological changes in mammalian breast cancer cells (MCF-7) undergoing UVA irradiation induced apoptosis. The values for the scattering anisotropy parameter (g) and reduced scattering coefficient [µs/ = µs (1-g), where µs is the scattering coefficient] of the control cell suspensions and cell suspensions irradiated to varying dosage of UVA (80 - 160 kJ / m²) were estimated for the wavelength range 450nm - 750 nm using integrating sphere measurements of diffuse reflectance and transmittance. These estimates were used to determine the Mie equivalent scatterer radius (r Mie) and thus quantify the morphological alterations of the cells. The value for r Mie was observed to decrease monotonically with increase in the UVA dose to up to a dose of 140 KJ/m² and showed an increasing behavior beyond this dose. Since it is known that while apoptosis leads to shrinkage in volume of the cells and fragmentation of nuclei, necrosis of the cells is associated with a swelling of cells, the results suggest that at doses below 140 kJ/m² cells undergo apoptosis and beyond this dose necrosis takes place. We also used the light scattering approach to monitor effect of He-Ne pre-irradiation on UVA induced damage in cells. Results were consistent with previous reports that suggest that He- Ne pre-irradiation can induce protection against the UVA damage to the cells.