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Ciprofloxacin-mediated cell proliferation inhibition and G2/M cell cycle arrest in rat tendon cells
Wen-Chung Tsai1, Chih-Chin Hsu, Fuk-Tan Tang
1Chang Gung Memorial Hospital Department of Physical Medicine and Rehabilitation, Chang Gung University College of Medicine, Taoyuan, Taiwan.
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.
Conclusion:
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.
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