Differential transactivation of human metallothionein-IIa in cisplatin-resistant and -sensitive cells

Oncol Res. 1998;10(2):85-98.


Cells with acquired anticancer drug resistance frequently exhibited broad cross-resistance to other anticancer agents. Increased human metallothionein (hMT) IIa transcription has been found in some cells with acquired resistance to cisplatin (CP). A panel of 5'hMT-IIa promoter deletions linked to the chloramphenicol acetyl transferase ((5'-hMT-IIaCAT) were used to demonstrate that certain cis-elements are important for the increased hMT-IIa transcription in CP-resistant cells (SCC25/CP) compared to CP-sensitive cells (SCC25). We further identified trans-acting factor differences between SCC25 and SCC25/CP cells using gel mobility shift assays. Significant increases in binding of specific factors to the -286 to -160 and -96 to -51 region were seen in CP-resistant SCC25/CP cells compared to sensitive SCC25 cells. Using cross-competition and super gel shift analyses, we identified enhanced Spl and AP-2 binding activity in SCC25/CP cells. By Western blot analysis and immunoprecipitation, we demonstrated that the level of Spl was unchanged between the two cells types whereas AP-2 was elevated twofold in SCC25/CP cells. Our results indicated that the selection of CP-resistant phenotype in SCC25/CP was accompanied by increased Spl and AP-2 DNA binding activities, which are likely not only to enhance hMT-IIa transcription but could also alter expression of other genes responsible for a broader anticancer drug cross-resistance. Thus, altered trans-acting factors could account for the complex cross-resistant phenotype found in some anticancer drug-resistant cells.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antineoplastic Agents / metabolism
  • Antineoplastic Agents / pharmacology
  • Carcinoma, Squamous Cell / genetics
  • Carcinoma, Squamous Cell / metabolism
  • Cell Nucleus / metabolism
  • Chloramphenicol O-Acetyltransferase / genetics
  • Chloramphenicol O-Acetyltransferase / metabolism
  • Cisplatin / pharmacology
  • Drug Resistance, Neoplasm / genetics
  • Electrophoresis, Agar Gel
  • Genes, Reporter
  • Genetic Vectors
  • Head and Neck Neoplasms / genetics
  • Head and Neck Neoplasms / metabolism
  • Humans
  • Metallothionein / genetics
  • Metallothionein / metabolism*
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / metabolism*
  • Promoter Regions, Genetic
  • Transcription, Genetic*
  • Transcriptional Activation*
  • Transfection
  • Tumor Cells, Cultured


  • Antineoplastic Agents
  • Neoplasm Proteins
  • Metallothionein
  • Chloramphenicol O-Acetyltransferase
  • Cisplatin