Thapsigargin resistance in human prostate cancer cells

Cancer. 2006 Aug 1;107(3):649-59. doi: 10.1002/cncr.22027.


Background: Thapsigargin (TG) is a potent inhibitor of sarcoplasmic/endoplasmic reticulum Ca2+ ATPases (SERCAs). TG-based prodrugs are being developed for the treatment of prostate cancer (PC). To develop optimal TG-based therapeutics it is important to understand the mechanisms of resistance to TG that may potentially occur in cancer cells.

Methods: DU145/TG and PC3/TG cells were derived from human PC DU145 and PC3 cells, respectively, by incremental exposure to TG. Growth assays, Western blot analyses, cDNA microarrays, semiquantitative and real-time polymerase chain reaction (PCR), Northern blot analyses, and immunohistochemistry were used to study these cells.

Results: DU145/TG cells are 1100-fold and PC3/TG cells are 1350-fold resistant to TG. Although expression of both SERCA and p-glycoprotein can mediate TG resistance in hamster cells, neither is modulated in DU145/TG cells. In contrast, in PC3/TG cells, SERCA, and not p-glycoprotein, is significantly overexpressed but cannot by itself account for the 1350-fold resistance to TG in these cells. Several genes not previously identified to be altered by TG selection are modulated in DU145/TG and PC3/TG cells. Furthermore, the spectrum of genes modulated in DU145/TG cells are distinct from that in PC3/TG cells, even though both cells are of prostate origin and share the same TG-resistant phenotype.

Conclusions: PC cells can adapt to SERCA inhibition by TG. However, they demonstrate cell type-specific plasticity with respect to gene expression upon TG selection. Further, previously not described mechanisms of resistance appear to be recruited in the TG-resistant PC cells, which provide a novel model to study mechanisms of resistance and adaptation in PC on TG-mediated dysregulation of Ca2+ homeostasis.

Publication types

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

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / analysis*
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / genetics
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism
  • Animals
  • Cell Line, Tumor
  • Cricetinae
  • Drug Resistance, Neoplasm*
  • Enzyme Inhibitors / pharmacology
  • Fibroblasts / metabolism
  • Gene Expression Profiling
  • Humans
  • Immunohistochemistry
  • Male
  • Oligonucleotide Array Sequence Analysis
  • Prostatic Neoplasms / drug therapy
  • Prostatic Neoplasms / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Thapsigargin / pharmacology*
  • Up-Regulation


  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Enzyme Inhibitors
  • Thapsigargin