ACTIVATION OF NUCLEAR FACTOR KAPPA-B - POTENTIAL ROLE IN METALLOTHIONEIN-MEDIATED MITOGENIC RESPONSE

The antiapoptotic response and enhanced cellular proliferation observe d in neoplastic cells on overexpression of metallothionein (MT) have b een well documented. We have investigated the mechanisms associated wi th this phenomenon by using MT inducers that increased MT transcripts and stimulated growth in MCF-7 cells. A MT antisense phosphorothioate oligonucleotide inhibited growth induction by >50%, suggesting a poten tial role of MT in mediating the mitogenic effects of these agents. Mo bility shift assays using oligonucleotides encompassing the consensus nuclear factor KB (NF kappa B) binding site and anti-MT antibody revea led activation and a specific interaction of NF kappa B with MT. Cotra nsfection experiments using expression and reporter constructs demonst rated that MT caused transactivation of NF kappa B. Gel shift assays u sing purified proteins showed a specific interaction between MT and th e p50 subunit of NF kappa B, These data indicate that MT may be involv ed in the interaction of NF kappa B with the DNA-binding domain and fu rther suggest a potential role for NF kappa B in mediating the antiapo ptotic effects of MT.