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  • SB 203580 br In the present cell viability assay most of


    In the present cell viability assay, most of the tested doses were 
    found to reduce cell viability in comparison with control samples. Despite differences between the cell lines, similar patterns were ob-served in both. EGCG showed the most effective action in combination with radiation doses of 0 and 2.5 Gy, with notable differences between 5-FU and 5-FU + ECGC, so that in some cases the combination of EGCG and 5-FU produced a larger decrease in cell viability than double the dose of 5-FU without EGCG. These findings imply that reducing 5-FU doses and adding EGCG will produce a greater effect on viability than increasing 5-FU doses alone. A previous study by Yang et al (Yang et al., 2012). concluded that EGCG sensitized hepatocellular carcinoma SB 203580 to 5-FU’s antitumoral activity, as well as on squamous cell carcinoma of the head and neck (Masuda et al., 2001). With the 5 Gy dose, EGCG would appear to lose its effect, as seen in other parts of the experiment. The reduced efficacy of EGCG could be due to its radioprotective effect. Kondo et al (Kondo, Park, Watanabe, Yamamoto, & Akashi, 2004) ob-served how EGCG inhibited apoptosis induced by radiation of human HaCaT keratinocytes via inhibition of the caspase cascade. However, our results differ to other studies, where this radioprotective effect only occurs on non-cancerous cells (Richi, Kale, & Tiku, 2012). This contrast in the results could be due to differences in the conditions of the ex-periments, variability of the cell lines used and the particular doses of radiation and concentrations of drugs used.
    Cancer cell migration is a part of the process whereby the primary tumor spreads to other organs. In previous research, both 5-FU and EGCG have been seen to reduce cell migration (Ho et al., 2007; Seo, Ki, Park, & Shin, 2017). In the present study, 5-FU produced a decrease in migration dose-dependently, while the addition of EGCG produced an even greater decrease. As with the cell viability assay, 5-FU + EGCG had the greatest action when combined with radiation doses of 0 and 2.5 Gy. This reduction of the cell migration could be caused by the decrease of the viability and the modification of the cell cycle, which is produced by the drugs used, avoiding the cells to develop their proper migration ability, as seen on the control values.
    The combination of 5-FU and 5-FU + EGCG with radiation altered the distribution of the cell cycle in comparison with control samples. In spite of differences between cell lines, two clear tendencies were ob-served. Firstly, the addition of EGCG to 5-FU increased the number of
    E. Pons-Fuster López, et al.
    cells in the G2/M phase. Secondly, 5-FU (and 5-FU + EGCG in the PE/ CA cell line) arrested the cell cycle in phase S, so that most cells were seen in this phase. In a previous study, 5-FU sequestered the breast cancer cell cycle in phase S (Grem, Nguyen, Monahan, Kao, & Geoffroy, 1999). Toden et al (Toden et al., 2016) observed that EGCG induced sequestration in phase G2 of colorectal cancer cells but in combination with 5-FU, the effects of 5-FU predominated, which modified the cell cycle arresting phase G0/G1. However, in the present experiment the effects of EGCG on the cell cycle predominated. Again, the contrasts between 5-FU and 5-FU + ECGC were greater in unirradiated cells and cells radiated at 2.5 Gy than at 5 Gy.
    In spite of the obtained data, the present experiment encountered two main limitations: the variability between cell lines and the scarcity of previous studies that have combined ECGC and 5-FU with radiation, hindering the comparison of the present results with other research findings. Nevertheless, it was observed that the addition of EGCG re-duced cell viability and migration and altered cell cycles to a greater extent than 5-FU alone, particularly without radiation or radiation at 2.5 Gy, given that when the radiation dose was increased to 5 Gy the effect of EGCG disappeared. The present findings would appear pro-mising but further research involving other clinical phases is necessary to improve therapeutic strategies while minimizing the adverse effects of chemoradiation therapy.