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Mechanisms of cadmium (Cd 2+ ) induced G2 phase cell cycle arrest in renal proximal tubule (PT) cells
Author(s) -
Bork Ulrich,
Lee WingKee,
Dittmar Thomas,
Thévenod Frank
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a506-a
Subject(s) - nocodazole , mitotic catastrophe , mitosis , cyclin dependent kinase 1 , cell cycle , programmed cell death , microbiology and biotechnology , checkpoint kinase 2 , cell cycle checkpoint , apoptosis , cyclin b1 , chek1 , chemistry , cell culture , cyclin b , biology , cyclin , cell , biochemistry , cytoskeleton , genetics
Cd 2+ induces apoptosis of PT cells. Cd 2+ also induces cell cycle arrest, but the underlying mechanisms remain unclear. We hypothesized that Cd 2+ induced stress causes G2 phase arrest by activating the ATM/ATR pathway. This results in activation of two downstream kinases, chk1 and chk2, which turn off the phosphatase cdc25c, thus preventing activation of the cdc2/cyclin B complex that enables cells to enter mitosis. The effects of Cd 2+ were investigated in an SV‐40 immortalized (p53‐inactivated) rat kidney PT cell line. FACS analysis was used for cell cycle analysis, MTT test for cell death quantification and immunoblotting for detection of cdc25c and cdc2. 50μM Cd 2+ for 6 h significantly increased PT cells in the G2/M phase by ~20%. This was increased ~two‐fold in nocodazole synchronized cells. Cd 2+ also induced ~20% cell death, which was further enhanced in synchronized cells. Inhibition of chk1 and chk2 with 300nM UCN‐01 significantly increased Cd 2+ toxicity by 30%. Immunoblots with antibodies to cdc25c and phospho‐cdc2 supported Cd 2+ induced activation of the ATM/ATR pathway in the G2 phase. We speculate that the increase in cell death induced by Cd 2+ after inhibition of chk1/chk2 with UCN‐01 results from damaged PT cells, which progress from the G2 phase to mitosis and then undergo cell death by mitotic catastrophe.