Ciprofloxacin-mediated cell proliferation inhibition and G2/M cell cycle arrest in rat tendon cells.
OBJECTIVE
To investigate the effect of ciprofloxacin on the proliferation and cell cycle progression of tendon cells, and to explore the potential molecular mechanism of ciprofloxacin-associated tendinopathy by analyzing the expression of cell cycle-related cyclin and cyclin-dependent kinase (CDK).


METHODS
Rat Achilles tendon cells were treated with ciprofloxacin and then assessed by MTT assay, flow cytometric analysis, and fluorescence confocal microscopy. Levels of messenger RNA (mRNA) for CDK-1 and cyclin B were determined by reverse transcriptase-polymerase chain reaction. Protein expression of CDK-1, cyclin B, checkpoint kinase 1 (CHK-1), and polo-like kinase 1 (PLK-1) was determined by Western blot analysis.


RESULTS
Ciprofloxacin inhibited tendon cell proliferation and caused cell cycle arrest at the G2/M phase. Confocal microscopy revealed that chromosomes in ciprofloxacin-treated cells neither properly aligned along the equatorial planes nor segregated successfully during metaphase. Mitotic arrest, misaligned chromosomes, and poor bipolar spindle formation were observed in ciprofloxacin-treated cells. CDK-1 and cyclin B protein and mRNA were both down-regulated. CHK-1 protein expression was also suppressed, but PLK-1 protein expression was up-regulated by ciprofloxacin.


CONCLUSIONS
Our findings suggest a possible mechanism of ciprofloxacin-associated tendinopathy. Down-regulation of CHK-1 and up-regulation of PLK-1 may account for mitotic arrest observed in ciprofloxacin-treated cells.
Chang Gung Memorial Hospital Department of Physical Medicine and Rehabilitation, Chang Gung University College of Medicine, Taoyuan, Taiwan.
Wen-Chung
WC
Tsai
Chih-Chin
CC
Hsu
Fuk-Tan
FT
Tang
Alice M K
AM
Wong
Yen-Ching
YC
Chen
Jong-Hwei S
JH
Pang
D000125:Achilles Tendon / Q000166:cytology* / Q000254:growth & development; D000818:Animals; D002453:Cell Cycle / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D002939:Ciprofloxacin / Q000494:pharmacology*; D018844:Cyclin-Dependent Kinases / Q000187:drug effects; D016213:Cyclins / Q000187:drug effects; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D052256:Tendinopathy / Q000139:chemically induced / Q000473:pathology
D016213:Cyclins; D019384:Nucleic Acid Synthesis Inhibitors; D002939:Ciprofloxacin; D018844:Cyclin-Dependent Kinases