Enhanced anti-proliferative and pro-apoptotic effects of metformin encapsulated PLGA-PEG nanoparticles on SKOV3 human ovarian carcinoma cells.

Metformin (MET) has received considerable attention in recent years for its anticancer potential activities. However, short half-life and weak bioavailability of MET limited its use as a chemotherapeutic agent. The present study is intended to evaluate the efficiency of PLGA-PEG as a nano-carrier for MET to increase anticancer effects on SKOV3 ovarian carcinoma cells. MET-loaded PLGA-PEG nanoparticles (NPs) were characterized through Dynamic Light Scattering (DLS), Fourier-transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FE-SEM). Anti-proliferative and apoptotic effects of nanoformulated MET were evaluated using MTT and flow-cytometric assays, respectively. Also, real-time polymerase chain reaction (Real-Time PCR) was used to determine the gene expression levels of apoptotic genes, p53 and hTERT. Evaluation of cytotoxicity showed that MET-NPs had more cytotoxicity than free MET in a time-and dose-dependent manner. The nuclei fragmentation and the percentage of apoptotic cells induced by MET-NPs were significantly higher than free MET. Also, it was found that MET-NPs triggered more cell cycle arrest at sub-G1 checkpoint than free MET. Compared to MET treated cells, the mRNA expression levels of apoptotic genes, as well as p53 and hTERT were significantly altered in MET-NPs treated cells. In conclusion, it is supposed that nano-encapsulation of MET into polymeric PLGA-PEG NPs may be a convenient drug delivery system to enhance its anticancer effects for ovarian cancer therapy.

Synergistic Anti-proliferative Effects of Metformin and Silibinin Combination on T47D Breast Cancer Cells via hTERT and Cyclin D1 Inhibition.

BACKGROUND: There is a growing body of data that chemotherapeutic combination strategies would be more effective in reducing drug toxicity, inhibiting tumor progression in comparison to either drug alone. OBJECTIVE: To explore a chemopreventive strategy for improving breast cancer treatment efficacy, the anticancer effects of a combination of Metformin (MET) and Silibinin (SIL) were investigated in T47D breast cancer cells. MATERIALS AND METHODS: Cytotoxicity of the drugs individually and in combination was evaluated using MTT assay. The precise nature of the interaction between MET and SIL was further analyzed through the median-effect method. In addition, qRT-PCR was applied to determine the expression levels of hTERT and cyclin D1 genes after 48 h drug exposure. RESULTS: MTT assays showed that MET and SIL individually inhibited the cell viability in a dose and time-dependent manner, and the obtained combination indices (CIs) were<1 for all the combination treatments, indicating that the anticancer agents synergistically induced growth inhibition in the breast cancer cells. qPCR findings revealed that the drug combination also synergistically down-regulated the expression levels of hTERT and cyclin D1 at all used concentrations compared with the drugs used alone after 48 h treatment (P≤0.05). CONCLUSION: The results provide evidence that synergistic antiproliferative effects of MET and SIL, linking to the down-regulation of Cyclin D1 and hTERT genes, and propose that MET+SIL may have therapeutic value in breast cancer therapy.

Combination of metformin and phenformin synergistically inhibits proliferation and hTERT expression in human breast cancer cells.

OBJECTIVES: Breast cancer remains a global challenge, and further chemopreventive therapies are still immediately required. Emerging evidence has revealed the potent anti-cancer effects of biguanides, Metformin (MET) and phenformin (PHE). Thus, to explore an efficient chemopreventive strategy for breast cancer, the antiproliferative effects of the combination of MET and PHE against breast cancer cells were assessed. MATERIALS AND METHODS: Cytotoxicity of the drugs individually and in combination against T47D and MDA-MB-231 breast cancer cells were assessed using MTT assay and the median-effect method was used to analyze the precise nature of the interaction between MET and PHE. Besides, the expression levels of hTERT after 48 hr drug exposure were determined using qRT-PCR. RESULTS: Based on the cytotoxicity assay, both MET and PHE further inhibited the growth of MDA-MB-231 cells compared with T47D cells. It was found that MET+PHE reduced the IC50s of MET and PHE in both cells drastically more than the single treatments in a synergistic manner. Importantly, MET+PHE showed higher antiproliferative effect with smaller IC50 values against MDA-MB-231 cells than against T47D cells. Real-time PCR results revealed that hTERT expression was significantly reduced in both breast cancer cell lines treated with MET+PHE than the single treatments. In comparison between two types of breast cancer cells, it was detected that MET+PHE could further decline hTERT expression in MDA-MB-231cells than in T47D cells (P<0.001). CONCLUSION: It is speculated that the combination of MET and PHE may be a promising and convenient approach to improve the efficiency of breast cancer treatment.speculated that the combination of MET and PHE may be a promising and convenient approach to improve the efficiency of breast cancer treatment.