Ultraviolet light and mitomycin C induced sister-chromatid exchanges in fibroblasts from patients with retinoblastoma

Photosensitization of MCF-7 cells with diaziquone using visible light: correlation with DNA strand breaks and free radical production

The ability of visible light to enhance the activity of diaziquone (AZQ) was evaluated in MCF-7 human breast cancer cells. MCF-7 cells were sensitive to AZQ, while visible light illumination had no appreciable effect on cell survival. In the presence of AZQ, visible light potentiated AZQ's cytotoxicity. This potentiation of AZQ activity correlated with a 2-2.5-fold increase in the formation of free radicals (hydroxyl radicals and AZQ semiquinone) and with the production of DNA strand breaks as measured by electron paramagnetic resonance and gel electrophoresis respectively. These results support the hypothesis that free radical formation is part of the mechanism of action of AZQ.

Sister chromatid exchange frequency in a retinoblastoma mosaic patient with del(13)

The frequencies of sister chromatid exchange (SCE) were investigated in different cell populations derived from a patient with retinoblastoma and 46,XY/46,XY,del(13) (q12.3q21.2) mosaicism. No differences in spontaneous or mitomycin C-induced SCE were detected between cell populations.

Chromosome abnormalities involving band 13q14 in hematologic malignancies

Fifteen patients with hematologic disorders showed abnormalities involving chromosome band 13q14. Nine patients had an interstitial deletion of this band, similar to that reported in some retinoblastoma tumors and as a constitutional abnormality in a small proportion of cases of familial retinoblastoma. In five patients, band 13q14 was involved in translocations and in one case there was a deletion of one chromosome #13 and a translocation involving the homologous #13. The diagnosis in the majority of our patients (11 of 15) was chronic lymphocytic leukemia. In these patients the abnormalities were detected in cultures stimulated with 4-phorbol 12-myristate 13-acetate (PMA). It is possible that the utilization of this agent is a fundamental requirement for the reliable demonstration of abnormalities involving 13q14 in patients with B-cell malignancies. The incidence of abnormalities involving 13q14 and their significance in the development of neoplasias, other than retino-blastoma, is discussed.