Metformin is the most widely used anti-diabetic drug in the world. It reduces advanced glycation end product (AGEs)-induced ROS generation in high glucose condition. Protein glycation contributes to skin aging as it deteriorates the existing collagen by crosslinking. The progressive increase of AGE during aging not only causes oxidative damage to cellular macromolecules but also modulates the activation of transcription factors nuclear factor kappa-B(NF-kB). However, it is still unclear whether metformin can change collagen production and NF-kB activity induced by high glucose conditions in 3T3 fibroblast. The effects of metformin on proliferation, apoptosis, and collagen levels and NF-kB activity of in vitro cell aging model of 3T3 fibroblast cells in high glucose conditions. At first, we investigated the effects of 50 mM high glucose concentration, with or without metformin, on 3T3 fibroblast proliferation, by BrdU immunostaining for cell proliferation. Apoptotic levels were analyzed by flow cytometric assay. NF-kB(p65) activity was measured by transcription factor assay kit and collagen I and III levels by Collagen Estimation Assay through ELISA. We observed that metformin exposure leads to decreased apoptosis levels and increased proliferation of 3T3 fibroblast in high glucose media. We also determined that metformin exposure leads to increased production of collagen I-III and decreased activation of NF-kB(p65) activity. The data are consistent with the observation that metformin has a protective effect in this in vitro model of aging 3T3 fibroblasts under high glucose conditions inducing cell proliferation, collagen I and III production, protection from apoptosis, and reducing NF-kB(p65) activity.

Cyclooxygenase (COX) inhibitors, already widely used for the treatment of pain and inflammation, are considered as promising compounds for the prevention and treatment of neoplasia. The aim of our study was to determine the direct antiproliferative effects of nonsteroidal anti-inflammatory drugs (NSAIDs), piroxicam and deracoxib, at a variety of concentrations as both single and combined treatments on canine mammary carcinoma cell line CMT-U27 and to understand the mechanisms of cell death. MTT assay was performed to determine cell viability, and flow cytometric analyses were performed to evaluate apoptosis and cell cycle alterations. Significant decrease in cell viability was observed at high concentrations of piroxicam and deracoxib in both single and combined treatments after 72 h incubation. Combined treatment produced a significantly greater inhibition than that caused by either agent alone. Also apoptotic cell number was increased by both drugs at the cytotoxic concentrations. However, concomitant treatment of cells with piroxicam and deracoxib resulted in significant induction of apoptosis at lower concentrations and accumulation of cells in the G0/G1 phase. Significant cytotoxic effects exhibited by the combination of piroxicam and deracoxib against canine mammary carcinoma cells in vitro suggest an attractive approach for the treatment of canine mammary carcinoma.

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Cyclooxygenase (COX) inhibitors have been shown to exert anti-angiogenic and anti-tumor activities on many types of malignant tumors. These anticancer properties make it worthwhile to examine the possible benefit of combining COX inhibitors with other anti-cancer agents. In the present study, we evaluated the potential of deracoxib (DER) in potentiating antitumor activity of doxorubicin (DOX) in canine mammary carcinoma cells (CMT-U27). DER (50–250 µM) enhanced the antiproliferative activity of DOX by reducing the IC50 (approximately 3- to 3.5 fold). Interaction analysis of the data showed that combinations of DOX at 0.9 µM with DER (100–250 µM) produced synergism in the CMT-U27 cell line, with a ratio index ranging from 1.98 to 2.33. In additional studies identifying the mechanism of observed synergistic effect, we found that DER strongly potentiated DOX-caused G0/G1 arrest in cell cycle progression. Also, DER (100–250 µM) augmented apoptosis induction with approximately 1.35- and 1.37- fold increases in apoptotic response caused by DOX in the cells. DER enhanced the antiproliferative effect of DOX in conjunction with induction of apoptosis by modulation of Bcl-2 expression and changes in the cell cycle of the CMT-U27 cell line. Although the exact molecular mechanism of the alterations in the cell cycle and apoptosis observed with DER and DOX combinations require further investigations, the results suggest that the synergistic effect of DOX and DER combinations in CMT therapy may be achieved at relatively lower doses of DOX with lesser side effects. Therefore, combining DER with DOX may prove beneficial in the clinical treatment of canine mammary cancer.