A biochemical and infrared study of the effect of radiation on TGase activity in normal and cancer cells

Abstract

Radiotherapy is widely used in cancer treatment, with a growing interest in knowing the effect of irradiation at cellular and molecular level. Keratinocyte cells from normal (HOK) or cancer (SCC25) cell lines have been subjected to different doses of radiation. Transglutaminase, is an enzyme involved in many cellular processes including apoptosis, sensitive to irradiation with the activity modified in cancer cells. The activity has been measured in both cell lines obtaining a 75% difference in activity, non-attributable to calcium. After subjecting the cells to different doses the activity at different times after irradiation shows that the response of normal and cancer cells is not alike, being the TGase activity in cancer cells less affected by irradiation. In both cases the activity is recovered after 24 h. The effect of irradiation on TGase activity on a purified protein has also been studied not only measuring the activity, but also to the changes of structure using IR spectroscopy. There is less effect of irradiation in the activity and small changes in the components of the amide I band associated with protein structure. The results would suggest that the effect of radiation is also dependent on the cellular structure.