IN-SITU CROSS-LINKING BY CISPLATIN OF NUCLEAR MATRIX-BOUND TRANSCRIPTION FACTORS TO NUCLEAR-DNA OF HUMAN BREAST-CANCER CELLS

Cisplatin is an antitumor drug that is used to treat several types of canters. In this study, we analyzed the proteins that were cross-linke d to DNA in situ in MCF-7 human breast cancer cells incubated with cis platin. We show that cisplatin cross-links nuclear matrix proteins to DNA. In immunoblotting experiments, we found that nuclear matrix-assoc iated transcription factors and cofactors (estrogen receptor, HET/SAF- B, hnRNP I;, and histone deacetylase 1) were cross-linked to nuclear D NA. These transcription factors and cofactors hale essential roles in the regulation of genes involved in the proliferation of breast cancer cells and in the organization and structure of chromatin. We applied a novel protocol to demonstrate that the nuclear matrix-bound transcri ption factors/cofactors were cross-linked to DNA fragments attached to the nuclear matrix. These results suggest that the cross-linking of n uclear matrix-associated transcription factors and cofactors to DNA ma y be one of the mechanisms by which cisplatin inhibits transcription a nd replication processes.