Spontaneous and 4-nitroquinoline 1-oxide-induced G2 chromosome aberrations in lymphoblasts from familial melanoma...

Lymphoblastoid cell lines established from three unrelated kindreds with familial melanoma (FM) were cytogenetically analyzed for spontaneous and 4-nitroquinoline-1-oxide (4NQO)-induced chromosome aberrations. There were no significant differences between control, FM, or xeroderma pigmentosum (XP) cell lines for spontaneous aberrations. As a group, FM patients, as well as XP patients, had significantly higher 4NQO-induced aberrations than controls when metaphase cells were analyzed 2.5 hours after treatment during the G2 phase of the cell cycle. When selected cell lines were analyzed 18 hours after 4NQO treatment, the frequency of chromosome aberrations in FM cells returned to spontaneous levels, but XP cells retained significantly elevated aberration frequencies. The wide variability for chromosome aberrations within the control. FM relative, and FM patient groups during G2, however, indicated that analysis of total breakage rates alone would not be predictive of susceptibility to FM. Heterogeneity for carcinogen-induced chromosome breakage between some cancer-prone individuals and the possible significance of site-specific chromosome aberrations are discussed.