الفهرس 
TitleOnly 14 pages are availabe for public view
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Abstract
Breast cancer is the most frequent diagnosed disease and the leading cause of cancer death in women all over the world. The incidence and mortality rates of breast cancer represented 24% and 15% respectively of all cancer types among females in 2018. BC may be attributed to many risk factors, that have a great influence on the development of the malignant tumor, including modifiable risk factors such as (obesity, smoking, alcohol consumption as a life style risk factors in addition to exposure to radiation, hormonal factors, and socioeconomic factors) and many other non-modifiable risk factors such as (gender, age, race, family history, benign diseases and genetic factors).
Treatment strategies of BC include surgical removal of the tumor, radiation therapy and adjuvant systemic therapy, the later includes adjuvant chemotherapy, neo-adjuvant chemotherapy, hormonal and palliative therapy. Doxorubicin is cytotoxic anthracycline antimetabolite and is probably the most chemotherapeutic drug used in the treatment of breast cancer, but the different side effects specially at high doses treatments as well as the fact that cancer cells become resistant after repeated and prolonged treatments remains a major obstacle towards a complete patient recovery using this drug. Therefore, many researchers are now examining the potential anti-cancer effect of various natural products found in food and plants to minimize the chemotherapy side effects mainly through their synergistic or additive effect therefore lowering the required doses of chemotherapeutic drugs.
Phytochemicals are a major class of natural products that are used as chemo preventive agents for all types of cancers in general and breast cancer specifically because of their high content of antioxidants. Epidemiological studies have indicated that high intake of fruits and vegetables are associated with a significant decrease in the risk of cancer incidence and development.
Many studies evaluated the potential effect of pomegranate extract on breast cancer in-vitro and in-vivo and it was found that pomegranate fruit especially its peel contains many polyphenols and tannins that found to have antitumor effect. Normal breast development is controlled by a balance between cell proliferation and apoptosis, and there is strong evidence that tumour growth is not just a result of uncontrolled proliferation but also of reduced apoptosis. The balance between proliferation and apoptosis is crucial in determining the overall growth or regression of the tumour in response to chemotherapy. Autophagy is the catabolic process of recycling cellular components to maintain cell viability against any stress; in addition it has a vital role in cancer progression and treatment. Current chemotherapeutic agents, which target autophagy, result in growth inhibition in many cancer types including breast cancer. Apoptosis and autophagy are now considered as key regulators of the possible chemotherapy resistance mechanisms. At present, the main strategy for overcoming drug
Summary, Conclusions & Recommendations
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resistance is the use of sensitizing agent combined with chemotherapeutic drugs and numerous studies have identified resistance reversal agents from natural products.
Therefore, reversing doxorubicin resistance through activation of apoptosis and autophagy down-regulation in cancer cells by using natural compounds could be an effective way in treating breast cancer.
The present study aimed to investigate the effect of single and combined treatments with doxorubicin and/or pomegranate peel extract on doxorubicin-sensitive (S-T-47D) and resistant (R-T-47D) breast cancer cells. Furthermore, the study investigated the mechanism of the potential anti-cancer effect of PE and DOX on both cells through the modulation of apoptosis and autophagy.
Initially, a DOX resistant T-47D cell line was developed by subculturing the T-47D parental cell line in gradually increasing concentrations of DOX. The IC50 for DOX in both sensitive and resistant cells was measured to select the treatment doses that will be used during the rest of the study. Morphological changes in S-T-47D and R-T-47D cells after DOX and/or PE and combined treatment was examined by inverted microscope. The expression levels of BAX, p53 and p21 proteins as biomarkers and modulators of apoptosis as well as LC3-II and Beclin-1as autophagy biomarkers were investigated by western blotting. Finally, the effect of different treatments on apoptosis induction through histone release and caspase-3 activity was detected by ELISA.
The results of the present study revealed that:
The IC50 of DOX in resistant cells was almost double that for sensitive cells (3800 ± 0.022 nM) compared to (2000 ± 0.02 nM).
Confirming the IC50 results, morphological changes after DOX treatment showed Cytotoxicity in R-T-47D cells at higher concentrations compared to S-T-47D cells.
Western blotting analysis of treated cell lysates showed that PE and combined treatment with DOX reduced the autophagy biomarker proteins LC3-II and Beclin- 1 in both cells.
Western blotting analysis also showed that PE and combined treatment with DOX up-regulated the apoptosis modulating and biomarker proteins BAX, p53 and p21 in both cells.
Histone release and caspase-3 activity were also induced by combined treatment more than DOX or PE alone in both cells.
In general, from the present study we can conclude that:
The response to treatment was less in resistant cells compared to sensitive cells with PE and combined treatment having the best effect.
In addition, the results indicated that PE treatment could re-sensitize resistant cancer cells towards chemotherapy effect through modulating autophagy and apoptosis process.
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Recommendations:
Further in vivo studies on PE anticancer effect, so PE can be used in combination with chemotherapy to maximize the anticancer effect of chemotherapy and to reduce its side effects as well as to reduce chemotherapy resistance.
Moreover, regularly PE intake in case of patients developing chemotherapy resistance may be an effective way in reducing resistance.