Metformin in combination with JS-K inhibits growth of renal cell carcinoma cells via reactive oxygen species activation and inducing DNA breaks

Abstract

Metformin (MET) is taken as a principal medication for remedying Type 2 diabetes mellitus. Its anti-tumor effect has been reported increasingly, but the precise mechanism of it remains unclear. This study aims to explore the efficacy of MET and MET combined with nitric oxide donor prodrug JS-K on the proliferation, apoptosis, and DNA damage in human renal cell carcinoma (RCC) cells, and investigate the possible molecular mechanism involved. The cell proliferation was tested through methyl-tetrazolium assay and cell apoptosis was ascertained by flow cytometry. The dihydroethidium and JC-1 fluorescent methods were used to detect Reactive oxygen species (ROS) and mitochondrial transmembrane potential (Δψm), respectively. Proteins associated with apoptosis and DNA damage were evaluated by Western blotting. Results showed that MET and JS-K could suppress cell growth, and the inhibition concentration 50 of treatment with MET combined with JS-K (MET + JS-K) showed more toxicity than individual agents on RCC cells. This augmented toxicity was associated with intracellular reactive oxygen species (ROS) level, mitochondrial membrane potential alteration, and induced DNA breaks. The results of Western blotting showed that the expression level of pro-apoptotic proteins, such as Bax, Bak, caspase-3, and caspase-9, was up-regulated, and the anti-apoptotic protein Bcl-2 was down-regulated after treatment using MET alone and MET + JS-K, correspondingly. Moreover, MET + JS-K inhibited the expression of cellular PCNA and Rad51, and immunofluorescence analysis of γH2AX proved that MET + JS-K enhanced DNA damage. In summary, the results of this research indicated that MET and JS-K inhibited RCC cell growth by activating ROS, targeting mitochondria-dependent apoptotic pathways, and inducing DNA breaks.

Combination of metformin and cold atmospheric plasma induces glioma cell death to associate with c-Fos

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The multifaceted roles of mitochondria at the crossroads of cell life and death in cancer

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Metformin Protects against Radiation-Induced Acute Effects by Limiting Senescence of Bronchial-Epithelial Cells

“…Metformin was already shown to successfully prevent cancer cell viability and cell proliferation by inducing G 2 /M cell cycle arrest in a dose and time-dependent fashion followed by programmed cell death induction, effects that were attributed to increased ROS levels [68]. Likewise metformin targeted mitochondria-dependent apoptosis, and inducing DNA breaks by activating ROS [71]. Moreover, ROS levels vary during cell cycle progression and peak in mitosis.…”