A Potential Role of Doxycycline in Cancer Chemotherapy

Category: Colorectal

Aims: Doxycycline, long-acting tetracycline, is well-known antibiotic used widely. Its works by inhibition of mitochondrial protein-synthesis, thus restricting oxidative-phosphorylation and reducing ATP synthesis. Recently, doxycycline has been shown to prevent metastatic invasion in cancer-cells by inhibiting matrix-metalloproteinase. We aimed to establish whether doxycycline affects vitality of cultured HT29 colorectal cancer-cells.

Methods: 2×10 4 HT29 cells were cultured in 24 well plates for 24 hours for cellular attachment and subsequently treated with 10µeg/ml of doxycycline for upto 4-days. The cells were stained for cytochrome-c-oxidase activity at different time points. In addition, 2×10 4 HT29 cells were treated with different concentrations of doxycycline for 3 days and then cell-proliferation (Picogreen) and cytotoxicity (Alamar-Blue) assays were performed in triplicates.

Results: Cytochrome-c-oxidase staining revealed a clear reduction in enzyme activity following 3 days of doxycycline treatment. After 3 days of treatment, a dose dependent decrease of cellular proliferation and dose dependent increase of cytotoxicity was observed.

Conclusion: After 3 days of treatment, doxycycline decreases cellular proliferation and increases cytotoxicity. This action of doxycycline may have a role in chemotherapy in future although the mechanism(s) by which doxycycline triggers cell death is subject to further study.