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Escherichia coli verotoxin 1 mediates apoptosis in human HCT116 colon cancer cells by inducing overexpression of the GADD family of genes and S phase arrest
Author(s) -
Bhattacharjee Rabindra N.,
Park Kwon-Sam,
Uematsu Satoshi,
Okada Kazuhisa,
Hoshino Katsuaki,
Takeda Kiyoshi,
Takeuchi Osamu,
Akira Shizuo,
Iida Tetsuya,
Honda Takeshi
Publication year - 2005
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2005.10.053
Subject(s) - dna laddering , apoptosis , biology , cell cycle checkpoint , microbiology and biotechnology , dna fragmentation , cell cycle , programmed cell death , annexin , dna damage , cell culture , flow cytometry , dna , biochemistry , genetics
The Escherichia coli verotoxin 1 (VT1) inhibits protein synthesis, cell proliferation, and damages endothelial cell in the hemolytic uremic syndrome. VT1 can specifically bind and act on endothelial cells as well as on many tumor cells because these cells express its high affinity receptor, globotriaosylceramide. This indicates that VT1 may have both antiangiogenic and antineoplastic activities. We investigated this potential of VT1 by incubating several colon cancer cell lines with VT1 for different time periods and found that HCT116 cells were especially sensitive to VT1. A combination of morphological studies, flow cytometry, DNA laddering and annexin V staining confirmed that VT1 irreversibly arrests these cells in S phase within 24 h and prolonged incubation triggers DNA fragmentation. Concomitant to the activation of the S phase checkpoint, increased levels of mRNA and proteins of growth arrest and DNA damage‐inducible gene family that include GADD34, GADD45α, and GADD45β was observed. Interestingly, no significant changes in expression of key cell cycle related proteins such as cdk2, cdk4, p21, p27, and p53 was found during the S phase arrest and apoptosis. We therefore suggest that GADD proteins might play an important role in VT1 induced S phase arrest and programmed cell death in HCT116 cells.