DNA repair following exposure of human lymphocytes to 4-nitroquinoline-1-oxide

✍ Scribed by Allan J. Jacobs; Richard L. O'Brien; John W. Parker; Patricia Paolilli

• Book ID: 102864665
• Publisher: John Wiley and Sons
• Year: 1972
• Tongue: French
• Weight: 658 KB
• Volume: 10
• Category: Article
• ISSN: 0020-7136
• DOI: 10.1002/ijc.2910100116

✦ Synopsis

Abstract

The carcinogen 4‐nitroquinoline‐1‐oxide (4NQO) is known to induce unscheduled DNA synthesis when administered to a number of mammalian cells. This effect was demonstrated in human lymphocytes. The degree of unscheduled DNA synthesis was found to be correlated with time and with 4NQO concentration. 4NQO was demonstrated to inhibit DNA replication in actively dividing lymphocytes.

In addition, human lymphocytes treated with the mitogen phytohemagglutinin‐M (PHA‐M) were allowed to incorporate bromodeoxyuridine (BUdR) into one chain of DNA in replicative synthesis. Following this, the BUdR was removed and the cells were incubated with 4NQO and tritiated thymidine. DNA isolated from these cells was fractionated by cesium chloride gradient centrifugation into a BUdR‐containing fraction of replicated DNA and a light fraction of DNA which had not yet replicated when incubated with BUdR. ^3^H‐thymidine was found in the heavy fraction of DNA from 4NQO‐treated cells which contained no newly replicated DNA. It was concluded that this represented repair synthesis.