Metallothionein isoform 1 and 2 gene expression in a human urothelial cell line (UROtsa) exposed to CdCl2 and NaAsO2.
Studies have shown that metallothionein (MT) is overexpressed in some human bladder cancers and that overexpression can predict treatment response to neoadjuvant cisplatin, methotrexate, and vinblastine chemotherapy. In the present study the UROtsa cell line, a model of normal human urothelium, was used to determine the expression of the human MT-1 and MT-2 genes and MT protein following exposure to CdCl(2) or NaAsO(2) at lethal and sublethal levels. Acute exposure was modeled by treating confluent cultures with 100 microM NaAsO(2) or 53.4 microM CdCl(2) for 4 h followed by a 48-h recovery period. Extended exposure was modeled by treating confluent cells with 1, 4, and 8 microM As(3+) or 1, 5, and 9 microM Cd(2+) for 16 d, with the highest concentrations producing cell lethality. The expression of MT mRNAs and protein were determined by reverse-transcription polymerase chain reaction (RT-PCR) and immunoblot analysis. Cell viability was determined by the MTT assay. It was shown that acute exposure to either As(3+) or Cd(2+) increased the levels of mRNAs for the MT-1E, MT-1X, and MT-2A genes, whereas extended exposure only increased these mRNAs following exposure to Cd(2+). It was shown that both acute and extended exposure to either As(3+) or Cd(2+) increased the levels of MT protein, reaching a maximal value of 8 ng MT protein/microg total protein for acute exposure to Cd(2+). This is in contrast to previous studies using cultured human proximal tubule cells, where similar extended treatment with Cd(2+) resulted in over 20-fold higher MT protein levels. These studies demonstrate that human urothelial cells accumulate only modest amounts of MT protein when exposed to either Cd(2+) or As(2+) for a 16-d time period.
Sens
Donald
D
Department of Surgery, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota 58202-9037, USA. dsens@medicine.nodak.edu
Rossi
Michael
M
Park
Seongmi
S
Gurel
Volkan
V
Nath
Joginder
J
Garrett
Scott
S
Sens
Mary Ann
MA
Somji
Seema
S
D018053:Arsenites / Q000633:toxicity*; D019256:Cadmium Chloride / Q000633:toxicity*; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000633:toxicity*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D008668:Metallothionein / Q000096:biosynthesis*; D017670:Sodium Compounds / Q000633:toxicity*; D019459:Urothelium / Q000166:cytology*
D018053:Arsenites; D004791:Enzyme Inhibitors; D017670:Sodium Compounds; C017947:sodium arsenite; D008668:Metallothionein; D019256:Cadmium Chloride