الفهرس 
TitleOnly 14 pages are availabe for public view
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Abstract
Breast cancer is one of the most prevalent cancers and the second-leading cause of death in women in developed countries. Although the etiology of breast cancer is not well known, several risk factors for the disease have been identified. Genetic, epigenetic, hormonal and environmental factors are contributing to the development of this disease. The treatment of breast cancer is complicated and includes the combination of surgery, radiotherapy, chemotherapy, hormonal or targeted therapy.
Even though the advances in neoadjuvant and adjuvant strategies for treating breast cancer, its management remains a serious problem. This has increased the urgency for extensive research to find new pathways or new agents for the treatment of breast cancer other than the well-known cytotoxic agents in a trial to get better effects with better tolerated side effects.
Due to the importance of AMPK and mTOR in the pathogenesis of breast cancer, our study was designed to investigate the effect of metformin, aspirin and their combination, through targeting AMPK and mTOR signaling pathways, on the growth and proliferation of mammary carcinoma induced in female mice.
Furthermore, the current work was also meant to compare between the efficacies of these probed drugs and to investigate the possible mechanisms of action of all used drugs to achieve best therapeutic management of breast cancer.
Fifty female Balb/c mice weighing between (20-25 g) were used in the current study. Ten mice were allowed to feed normal diet to serve as a negative control. The other 40 mice were subjected to the induction of mammary carcinoma by ehrlich ascites carcinoma (EAC) cells that were implanted subcutaneously in the mammary fat pad of mice by inoculation of 0.2 ml of 2×105 tumor cells in a physiological solution. When the tumor reached a considerable size, tumor-bearing mice were randomly assigned to four experimental groups (each of 10 mice) as follows: group I: Tumor-bearing control group: Mice were served as positive control for the treated animals and received only 0.3 ml of gum acacia 2% orally. group II: Metformin-treated group: Mice received metformin 250 mg/kg/day orally group III: Aspirin-treated group: Mice received aspirin 100 mg/kg/day orally.
group IV: Combined metformin and aspirin-treated group: Mice received a combination of metformin and aspirin as in previously mentioned groups II,III. All the probed drugs were dissolved or suspended in 0.3 ml of gum acacia 2% so that the total volume of 0.3 ml gum acacia contained the required dose of the drugs per kg and were given for a treatment period of 28 successive days. Tumor volumes were measured at the start of the treatment and at weekly intervals during the treatment period to assess the effect of different drugs on the rate of tumor growth. At the end of the experimentation
Summary, C onclusions & Recommendations
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period and after an overnight fast, blood samples were collected from the retro orbital venous plexus of the mouse. Serum samples were separated and used for estimation of angiopoietin-2 concentration by enzyme linked immunosorbent assay (ELISA) (marker of angiogenesis). Animals were then sacrificed, tumors were excised and tissue homogenates were prepared for determination of AMPK concentration by ELISA, beclin-1 concentration by ELISA (marker of autophagy) and mTOR expression by real time PCR. Tumor tissue sections were also used for determination of Ki67 expression (proliferation marker) and histopathological (H & E) examination. Livers were also isolated, homogenized using the specific homogenizing solution and used for determination of malondialdehyde (MDA) (a marker of oxidative stress) and reduced glutathione (GSH) concentration (antioxidant marker). Results of the present work revealed that the untreated EAC-induced mammary carcinoma bearing mice had a marked, progressive increase in tumor volume along the course of the experiment. Treatment with metformin and combined therapy significantly decreased the rate of mammary tumor growth throughout the period of the experiment as compared to the untreated mammary carcinoma bearing mice. However, aspirin showed a non-significant decrease in the rate of mammary tumor growth. Furthermore, results of the present study demonstrated that metformin produced the most favorable response on the rate of mammary tumor growth among all the studied groups. Its antitumor effect was elicited through inhibition of angiogenesis, activation of AMPK, induction of autophagy, inhibition of mTOR, inhibition of tumor cell proliferation and through an antioxidant effect. Combined therapy were in the second rank following metformin in reducing the rate of mammary tumor growth and inhibition of tumor cell proliferation with no significant difference between both of them. However, combined therapy was associated with more favorable effect than metformin in inhibition of angiogenesis, activation of AMPK, induction of autophagy, inhibition of mTOR and antioxidant effects. Although aspirin treatment didn’t show a significant effect on tumor growth or cell proliferation, it had a significant effect in decreasing angiogenesis, increasing AMPK level, triggering autophagy, decreasing mTOR expression and also had an antioxidant effect. Taken together, this work provided evidence that each of metformin, combined metformin and aspirin therapy and to lesser extent aspirin alone exerted antitumor effect on breast cancer induced in mice via numerous mechanisms of actions.