The influence of cathepsin B and leupeptin on potentially lethal damage repair in mammalian cells

• Published in: International journal of radiation oncology, biology, physics Vol. 16; no. 3; pp. 707 - 714
• Main Authors: Osmak, M., Korbelik, M., Suhar, A., Skrk, J., Turk, V.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY Elsevier Inc 01.03.1989; Elsevier
• Subjects: Animals; Aspartic Acid Endopeptidases; Biological and medical sciences; Biological effects of radiation; Cathepsin B; Cathepsin B - pharmacology; Cell Line; Cell Survival - drug effects; Cell Survival - radiation effects; Cell-culture; Cysteine Endopeptidases - metabolism; DNA - radiation effects; DNA Repair - drug effects; Endopeptidases - metabolism; Fundamental and applied biological sciences. Psychology; Leupeptin; Leupeptins - pharmacology; Mutation; Oligopeptides - pharmacology; PLDR; Radiosensitizing agents. Photosensitizing agents. Thermosensitizing agents; Serine Endopeptidases - metabolism; Tissues, organs and organisms biophysics; Cathepsin B; Leupeptin; Cell-culture; PLDR; Cell culture; Radiobiology; Proteinase; Potentially lethal radiodamage
• ISSN: 0360-3016; 1879-355X
• DOI: 10.1016/0360-3016(89)90489-6

Cell response to irradiation depends on many micro-environmental and intracellular factors. It is known that proteinases control many physiological functions and are also involved in progression of the cell cycle. They also could be involved in cell response to irradiation. In this work the influence of cathepsin B, which is one of the important lysosomal proteinases, and one of its inhibitors, leupeptin, on the potentially lethal damage repair (PLDR) was studied. Chinese hamster V79 cells were irradiated with gamma rays in the plateau-phase of growth. Immediately after irradiation cathepsin B or leupeptin were added to the growth medium. Four hours later, a determined sufficient period of time for maximal PLDR, the cells were replated to assess survival and mutation induction. Mutation frequency was determined at the hypoxanthine-guanine phosphoribosyltransferase (HGPRT) locus using resistance to 6-thioguanine (6-TG). Simultaneously, the activity of cysteine, aspartic and serine proteinases were determined at different postirradiation intervals. The results show that when plateau phase cells were incubated with cathepsin B during the postirradiation interval strong inhibition of PLDR was observed, accompanied with a reduced number of 6-TG resistant mutants. If leupeptin was added, more modest inhibition of PLDR was observed, accompanied with only slight reduction in the mutation frequency. The addition of cathepsin B or leupeptin to irradiated cells modified the activities of intracellular proteinases. As the highest alterations in proteinase activities were observed at the time when maximum repair of DNA lesions occurred, the biological consequences could involve a series of sequential steps in intracellular proteinase activities.