Tamoxifen and the PI3K Inhibitor: LY294002 Synergistically Induce Apoptosis and Cell Cycle Arrest in Breast Cancer MCF-7 Cells.

Breast cancer is considered as one of the most aggressive types of cancer. Acquired therapeutic resistance is the major cause of chemotherapy failure in breast cancer patients. To overcome this resistance and to improve the efficacy of treatment, drug combination is employed as a promising approach for this purpose. The synergistic cytotoxic, apoptosis inducing, and cell cycle effects of the combination of LY294002 (LY), a phosphatidylinositide-3-kinase (PI3K) inhibitor, with the traditional cytotoxic anti-estrogen drug tamoxifen (TAM) in breast cancer cells (MCF-7) were investigated. LY and TAM exhibited potent cytotoxic effect on MCF-7 cells with IC50 values 0.87 µM and 1.02 µM. The combination of non-toxic concentration of LY and TAM showed highly significant synergistic interaction as observed from isobologram (IC50: 0.17 µM, combination index: 0.18, colony formation: 9.01%) compared to untreated control. The percentage of early/late apoptosis significantly increased after treatment of MCF-7 cells with LY and TAM combination: 40.3%/28.3% (p < 0.001), compared to LY single treatment (19.8%/11.4%) and TAM single treatment (32.4%/5.9%). In addition, LY and TAM combination induced the apoptotic genes Caspase-3, Caspase-7, and p53, as well as p21 as cell cycle promotor, and significantly downregulated the anti-apoptotic genes Bcl-2 and survivin. The cell cycle assay revealed that the combination induced apoptosis by increasing the pre-G1: 28.3% compared to 1.6% of control. pAKT and Cyclin D1 protein expressions were significantly more downregulated by the combination treatment compared to the single drug treatment. The results suggested that the synergistic cytotoxic effect of LY and TAM is achieved by the induction of apoptosis and cell cycle arrest through cyclin D1, pAKT, caspases, and Bcl-2 signaling pathways.

The carotenoid fucoxanthin can sensitize multidrug resistant cancer cells to doxorubicin via induction of apoptosis, inhibition of multidrug resistance proteins and metabolic enzymes.

BACKGROUND: Multidrug resistance (MDR) causes failure of doxorubicin therapy of cancer cells, which develops after or during doxorubicin treatment resulting in cross-resistance to structurally and functionally-unrelated other anticancer drugs. MDR is multifactorial phenomenon associated with overexpression of ATP-binding cassette (ABC) transporters, metabolic enzymes, impairment of apoptosis, and alteration of cell cycle checkpoints. The cancer-prevention of the dietary carotenoid; fucoxanthin (FUC) has been extensively explored. Nevertheless, the underlying mechanism of its action is not full elucidated. HYPOTHESIS/PURPOSE: Investigation of the underlying mechanism of MDR reversal by the dietary carotenoid fucoxanthin (FUC) and its ability to enhance the doxorubicin (DOX) cytotoxicity in resistant breast (MCF-7/ADR), hepatic (HepG-2/ADR), and ovarian (SKOV-3/ADR) cell lines. METHODS: The synergistic interaction of FUC and DOX was evaluated using several techniques, viz.; MTT assay, ABC transporter function assays using FACS and fluorimetry, enzyme activity via spectroscopy and luminescence assays, and apoptosis assay using FACS, and gene expression using RTPCR. RESULTS: FUC (20 µM) synergistically enhanced the cytotoxicity of DOX and significantly reduced the dose of DOX (FR) in DOX resistant cells (MCF-7/ADR), hepatic (HepG-2/ADR), and ovarian (SKOV-3/ADR) to 8.42-(CI= 0.25), 6.28-(CI= 0.32), and 4.56-fold (CI=0.37) (P<0.001). FUC significantly increased the accumulation of DOX more than verapamil in resistant cells by 2.70, 2.67, and 3.95-fold of untreated cells (p<0.001), respectively. A FUC and DOX combination significantly increased the Rho123 accumulation higher than individual drugs by 2.36-, 2.38-, 1.89-fold verapamil effects in tested cells (p<0.001), respectively. The combination of the FUC and DOX decreased ABCC1, ABCG2, and ABCB1 expression. The FUC and DOX combination increased the levels and activity of caspases (CASP3, CASP8) and p53, while decreased the levels and activity of CYP3A4, GST, and PXR in resistant cancer cells. The combination induced early/late apoptosis to 91.9/5.4% compared with 0.0/0.7% of untreated control. CONCLUSION: Our data suggests a new dietary and therapeutic approach of combining the FUC with DOX to overcome multidrug resistance in cancer cells. However, animal experiments should be conducted to confirm the findings before applying the results into clinical trials.

Evaluation of the Diagnostic and Predicative Values of 8-Iso-Prostaglandin F2α as a Biomarker of Breast Cancer.

BACKGROUND: Breast cancer (BC) is a commonly reported cancer that is widely prevalent among women. Its early detection improves patient survival and results in better outcomes. For diagnosis and follow-up care, tumor markers are one of the feasible investigations to be ordered. 8-Iso-prostaglandin F2α (8-iso-PGF2α) serves as a serum marker reflecting oxidative stress and subsequent damaging of DNA. In the present study, we aimed to evaluate both diagnostic and predictive values of 8-iso-PGF2α in BC patients. MATERIALS AND METHODS: Serum levels of 8-iso-PGF2α were assessed for 66 women with benign breast tumors and 65 women who had malignant BC. To compare the patients who had breast tumors with healthy individuals, 63 women free of breast diseases were selected as controls. RESULTS: The serum level of 8-iso-PGF2α in the BC patients (57.92 pg/mL) was significantly higher compared to those with benign tumors (18.89 pg/mL) (p < 0.001). In addition, individuals with no breast diseases had less 8-iso-PGF2α (4.02 pg/mL) compared to those who had developed a tumor (p < 0.001). Serum 8-iso-PGF2α was found to be positively correlated with both carcinoembryonic antigen (r = 0.74, p < 0.001) and cancer antigen 15-3 (r = 0.80, p < 0.001). Furthermore, serum 8-iso-PGF2α showed high diagnostic performance in BC (AUC = 0.999, sensitivity = 100%, specificity = 99.2% at a cutoff value of 36.18 pg/mL). CONCLUSIONS: Our study found that the high level of serum 8-iso-PGF2α helps to provide a non-invasive indicator to detect BC. Future work with a larger sample size and various phases of BC can confirm the current results which provide insights into the early detection of cancer.

8-Hydroxy-2'-deoxyguanosine as a Discriminatory Biomarker for Early Detection of Breast Cancer.

BACKGROUND: Breast cancer (BC) is one of the most prevalent and reported cancers among Saudi women. Detection of BC in the early invasive stage (stages I, II) has an advantage in treating patients over detection in the late invasive stage (stages III, IV). Tumor markers are used to aid in diagnosis, treatment monitoring, and recurrence detection of malignant tumors. 8-hydroxy-2'-deoxyguanosine (8-OHdG) is a marker of nucleic damage owing to oxidative stress. PATIENTS AND METHODS: We studied the blood levels of 8-OHdG in 50 women with benign breast tumors, 50 women with BC, and 50 healthy women as a control group. RESULTS: The concentrations of 8-OHdG were significantly increased in the BC group (55.2 ng/dL) compared with the benign tumor group (30.2 ng/dL) and with the healthy control group (9.08 ng/dL). The same pattern was observed with other diagnostic markers, including carcinoembryonic antigen and cancer antigen 15-3. Significant positive correlations between 8-OHdG and both carcinoembryonic antigen (r = 0.63; P < .001) and cancer antigen 15-3 (r = 0.51; P < .001) were noticed. The levels of 8-OHdG were significantly higher in stage I (81 ng/dL) compared with stage II (51 ng/dL; P < .05), stage III (38 ng/dL; P < .01), and stage IV (19 ng/dL; P < .001). In addition, serum 8-OHdG had a high diagnostic performance in BC (area under the curve, 0.86; sensitivity = 82%; specificity = 80% at cutoff value 21.4 ng/mL). 8-OHdG is associated with BC risk according to logistic regression analysis. CONCLUSION: We concluded that the significant increase of serum levels of 8-OHdG in patients with BC can be used as a potential noninvasive biomarker for early detection of BC. However, large sample sizes from different stages and types of BC should be included in any future study to confirm the present findings before translating the findings into routine clinical application.