Silencing of the caspase-1 gene occurs in murine and human renal cancer cells and causes solid tumor growth in vivo

Int J Cancer. 2001 Mar 1;91(5):673-9. doi: 10.1002/1097-0215(200002)9999:9999<::aid-ijc1113>;2-u.


Renal cell cancer is a unique solid tumor that occasionally shows spontaneous regression even at an advanced stage, of which the underlying mechanism is not well understood. To investigate a potential role of the pro-apoptotic molecule caspase-1 in the growth regulation of renal cell cancer, we created transfectants expressing exogenous caspase-1 from a murine renal cancer cell line, Renca. Overexpression of caspase-1 did not affect the growth of Renca cells in vitro at the exponential phase but induced apoptotic cell death at 50% to 75% confluence, whereas control cells underwent apoptosis only after reaching 100% confluence. When implanted into the flank of a syngeneic BALB/c mouse, caspase-1-overexpressing Renca cells did not effectively establish growth as a solid tumor, forming a measurable tumor in only 7 of 11 (64%) animals, whereas control cells formed a tumor in 6 of 6 (100%) animals. The growth of tumors from caspase-1-overexpressing cells slowed down markedly after the tumors reached 5 to 10 mm in diameter, and histological examination of such tumors revealed numerous apoptotic cells positively stained by TUNEL assay. Interestingly, endogenous caspase-1 was not detected in the tumors from control cells, which re-expressed caspase-1 when they were re-cultured and exposed to a demethylation reagent, 5-aza-2'-deoxycytidine. Furthermore, treatment of a human renal cancer cell line, ACHN, with 5-aza-2'-deoxycytidine also caused recovery of caspase-1 expression, which was not detected before treatment. These data suggest that silencing of caspase-1 through DNA methylation may be involved in the oncogenesis of some renal cell cancers growing as a solid tumor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Azacitidine / analogs & derivatives*
  • Azacitidine / pharmacology
  • Caspase 1 / genetics*
  • Cell Division
  • Coloring Agents / pharmacology
  • DNA Methylation
  • DNA, Complementary / metabolism
  • Decitabine
  • Enzyme Inhibitors / pharmacology
  • Gene Silencing*
  • Genetic Vectors
  • Humans
  • Immunohistochemistry
  • In Situ Nick-End Labeling
  • Kidney Neoplasms / enzymology*
  • Kidney Neoplasms / genetics*
  • Mice
  • Mice, Inbred BALB C
  • Neoplasm Transplantation
  • Plasmids / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Tetrazolium Salts / pharmacology
  • Thiazoles / pharmacology
  • Time Factors
  • Transfection
  • Tumor Cells, Cultured
  • fas Receptor / metabolism


  • Coloring Agents
  • DNA, Complementary
  • Enzyme Inhibitors
  • Tetrazolium Salts
  • Thiazoles
  • fas Receptor
  • Decitabine
  • Caspase 1
  • thiazolyl blue
  • Azacitidine