Breast cancer is the most common cancer in the Arab world and it ranked first among Saudi females. Doxorubicin (DOX), an anthracycline antibiotic is one of the most effective anticancer agents used to treat breast cancer. chronic cardiotoxicity is a major limiting factor of the use of doxorubicin. Therefore, our study was designed to assess the role of a natural product resveratrol (RSVL) on sensitization of human breast cancer cells (MCF-7) to the action of DOX in an attempt to minimize doxorubicin effective dose and thereby its side effects.

Doxorubicin (DOX), an anthracycline antibiotic is one of the most effective anticancer drug used in the treatment of variety of cancers .Its use is limited by its cardiotoxicity. The present study was designed to assess the role of a natural product resveratrol (RSVL) on sensitization of mammary carcinoma (Ehrlich ascites carcinoma) to the action of DOX and at the same time its protective effect against DOX-induced cardiotoxicity in rats.

Cisplatin (CIS) is one of the most effective anticancer drug used in the treatment of several solid tumors .Its use is limited by its nephrotoxicity. The present study was designed to assess the role of a natural product resveratrol (RSVL) on sensitization of mammary carcinoma (Ehrlich ascites carcinoma) to the action of CIS and the possible protective effect against CIS-induced nephrotoxicity in rats. The percent survival of female tumor bearing mice was used for determination the cytotoxic activity of CIS in the presence or the absence of RSVL. Uptake and cell cycle effect, serum creatinine (CREA), blood urea nitrogen (BUN), Reduced Glutathione (GSH) and histopatholgical examination of kidney tissues after CIS and/or RSVL therapy were also investigated. RSVL increased the intracellular level of CIS in EAC cells and there was a strong correlation between the high cellular level of CIS and its cytotoxicity. CIS at a dose level of 5 mg/kg increased the mean survival time of female tumor bearing mice to 25 days compared with 17 days for tumor-bearing control mice. Administration of RSVL at a dose level of 25 mg/kg simultaneously with CIS increased the mean survival time to 48 days with 60% survival of the tumor-bearing animals. Cell cycle analysis of tumor cells showed that CIS treatment decreases the proliferation index of tumor cells while in presence of RSVL there was more significant inhibitions. Also, CIS treatment caused increase in level of creatinine and blood urea with significant decrease in the GSH level. While, in the presence of RSVL, level of creatinine and blood urea restored to control level. This study suggests that RSVL could increase the cytotoxic activity of CIS and protect against its nephrotoxicity.

Background: Hormonal receptor positive (HR+) breast cancer is the most commonly diagnosed molecular subtype of breast cancer; which showed good response to doxorubicin (DOX)-based chemotherapy. Eugenol (EUG) and astaxanthin (AST) are natural compounds with proved epigenetic and immunomodulatory effects in several cancer cell lines. This study has been initiated to investigate the molecular mechanism (s) whereby EUG and AST could enhance DOX cytotoxicity in MCF7 cells. Methods: Cytotoxic activity of DOX alone and combined with either 1 mM EUG or 40 μM AST was performed using sulphorhodamine-B assay in MCF7 cells. Global histones acetylation and some immunological markers were investigated using ELISA, western blotting and quantitative RT-PCR techniques. Functional assay of multidrug resistance was performed using rhodamine 123 and Hoechst 3342 dyes. Flow cytometry with annexin V and propidium iodide were used to assess the change in cell cycle and apoptosis along with the expression of some differentiation, apoptosis and autophagy proteins. Results: DOX alone resulted in concentration-dependent cytotoxicity with IC₅₀ of 0.5 μM. Both EUG and AST significantly increased DOX cytotoxicity which is manifested as a significant decrease in DOX IC₅₀ from 0.5 μM to 0.088 μM with EUG and to 0.06 μM with AST. Combinations of DOX with 1 mM EUG or 40 μM AST significantly increased the level of histones acetylation and histone acetyl transferase expression, while reduced the expression of aromatase and epidermal growth factor receptor (EGFR) when compared with 0.25 μM DOX alone. Also both combinations showed higher uptake of rhodamine but lower of Hoechst stains, along with increased the percentage of caspase 3, and decreased the expression of CK7 and LC3BI/II ratio. EUG combination induced IFγ but reduced TNFα causing shifting of cells from G2/M to S and G0/ G1 phases. Combination of DOX with EUG induced apoptosis through the higher BAX/ BCl2 ratio, while with AST was through the increase in caspase 8 expressions. Conclusion: EUG and AST potentiated the anticancer activity of DOX through epigenetic histones acetylation along with the immunonomodulation of different apoptotic approaches in MCF7 cells.

Doxorubicin (DOX) is one of the most important anticancer agents used in treating breast cancer. However, chronic cardiotoxicity and multidrug resistance limit the chemotherapeutic use of DOX. This study aimed to evaluate the capability of calcium channel blocker diltiazem (DIL) to reverse DOX resistance in breast cancer MCF-7 cells and to confer protection against DOX-induced cardiotoxicity in Wistar rats. For this purpose, we explored the effects of DOX on cell cycle phase distribution and expression of ABCB1, FOXO3a, and p53 genes in the presence and absence of DIL (20 μg/ml) and studied the ability of DIL to prevent DOX-induced cardiotoxicity after a single injection of DOX (15 mg/kg) in male Wister rats. We found that compared with DOX alone treatment, DIL + DOX treatment down regulated the ABCB1 gene expression by > fourfold but up regulated the FOXO3a and p53 genes expression by 1.5 fold. DIL treatment conferred protection against DOX-induced cardiotoxicity, as indicated by a decrease in the levels of the cardiac enzyme creatine kinase MB and malondialdehyde and an increase in the total antioxidant capacity and glutathione peroxidase levels. These biochemical results were further confirmed by the histopathological investigation of cardiac cells, which showed normal cardiac cells with central vesicular nuclei and prevention of DOX-induced disruption of normal cardiac architecture in the DIL to DOX group. Taken together, our results indicate that DIL treatment can reverse the resistance of breast cancer cells to the therapeutic effects of DOX and can protect against DOX-induced cardiotoxicity in rats.