الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Recent studies demonstrated the significant inhibitory effect of phytochemicals on cancer cells progression and development. Other studies illustrated the great ability of phytochemicals to treat several diseases such as stroke, Alzheimer’s and autoimmune diseases, as well as their anti-bacterial and anti-viral effects. Quercetin (Q) is one of the most important flavonoids ; due to its ability to interfere with vital biological pathways, such as those leading to programmed cell death, drug resistance, and targeting of oncogenes leading to cancerous tumors development and progression. The current study was aimed to elevate the bioavailability of Quercetin by loading it into a formulated pluronic-chitosan nanoparticle to enhance its effectiveness in targeting proliferation, survival and motility of HepG2 cell line. The study groups were divided into: group I: Cancer cells with no treatment (control group). group II: Cancer cells treated with the effective dose of quercetin that kills 50% of cells Q50 (23.46) µg/ml.
group III: Cancer cells treated with the effective dose of quercetin loaded on pluronic-chitosan nanoparticles that kill 50% of cells QN50 (18.21) µg/ml. group IV: Cancer cells treated with half of EC50 of quercetin that kills 25% number of cells Q50/2 (11.73) µg/ml. group V: Cancer cells treated with half of EC50 of quercetin loaded on pluronic-chitosan nanoparticles that kill 25% of the number of cells QN50/2 (105.9) µg/ml. The effect of QN on gene expression, cell division and progression of hepatic cancer cells was assessed in each group and compared to control cells and to free Q. Data assessment among treated groups revealed significant increase at the effect of quercetin after loading on pluronic-chitosan nanoparticles QN compared to free quercetin Q. The significance of QN loading in nanoparticles compared to free Q in ceasing cell proliferation was confirmed by flowcytometric analysis of cell cycle phases which indicated the significant time dependent effect of QN in induction of cell cycle arrest at G1/S phase. The ability of QN to cease cell cycle at day four of treatment compared to day 1 support our hypothesis of the role of nano-loaded phytochemicals sustained release in enhancing their anticancer characteristics. These results were in correspondence with the statistical analyses of cell proliferation assay (MTT assay) that indicated a significant increase at QN inhibitory effect on cell proliferation which was proportional to the length of exposure to QN. The proapoptotic effect of Q and QN was indicated by flowcytomtric analyses which indicated a significant increase at the percentage of annexin V labelled cells in QN treated groups compared to free Q. The molecular validation of QN proapoptotic effect via testing two different pathways using immunocytochemical analyses. The marked upregulation of P53 expression upon treatment with QN in comparison with Q and control cells indicated its targeting of P53 dependent apoptosis pathway. The marked downregulation at the expression of antiapoptotic protein surviving and its transcriptional factor E2F1 as well indicated the ability of QN in targeting different pathways in order to induce cell apoptosis. Moreover, the enhancement at induction of cell apoptosis that been shown by application of QN was corelated to the downregulation at expression of MDR1 gene which resulted in an increase at cell sensitivity to drugs. A significant responsiveness was shown by cells treated with QN compared to Q treated cells. Finally, the resulting data for gene expression (CD44) ,which is one of the main factors implicated in promoting cancer cell motility, showed a regression in gene expression in groups treated with QN compared to groups treated with Q that supported what been observed previously in cell migration assay reflecting the significant effect of QN to inhibit HepG2 cell migration. Conclusion: Our results indicated that loading of quercetin on pluronic-chitosan nanoparticles improved the efficiency of Q as an alternative therapeutic approach for liver cancer. The significant effect of QN in inhibiting HepG2 cell proliferation, survival, motility and drug resistance was molecularly validated via cell proliferation assays, the downregulation of surviving, E2F2, upregulation of P53 and downregulation of CD44 and MDR1, respectively. Relying on these results, we may recommend a further studies of application of QN in upcoming clinical trials either solitary or in combination with other conventional therapies.