Browsing by Author "Surichan, Somchaiya"

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    Antiproliferative and cytostatic effects of the natural product eupatorin on MDA-MB-468 human breast cancer cells due to CYP1-mediated metabolism
    (BioMed Central, 2008) Androutsopoulos, Vasilis; Arroo, R. R. J.; Hall, J. F.; Surichan, Somchaiya; Potter, Gerard A.
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    Bioactivation of the citrus flavonoid nobiletin by CYP1 enzymes in MCF7 breast adenocarcinoma cells
    (Elsevier, 2012) Surichan, Somchaiya; Androutsopoulos, Vasilis; Sifakis, S.; Koutala, E.; Tsatsakis, A.; Arroo, R. R. J.; Boarder, M. R.
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    Nobiletin bioactivation in MDA-MB-468 breast cancer cells by cytochrome P450 CYP1 enzymes.
    (Elsevier, 2018-01-31) Surichan, Somchaiya; Arroo, R. R. J.; Ruparelia, K. C.; Tsatsakis, A. M.; Androutsopoulos, V.P.
    Nobiletin is a fully methoxylated flavone that has demonstrated anticancer activity via multiple modes of action. In the present study, the metabolism and further antiproliferative activity of nobiletin was evaluated in the CYP1 expressing human breast cancer cell line MDA–MB–468 and the normal breast cell line MCF10A. Nobiletin was metabolized in MDA–MB–468 cells to a single-demethylated derivative assigned NP1. This metabolite was absent in MCF10A cells that did not express CYP1 enzymes. Nobiletin exhibited submicromolar IC50 (0.1±0.04 μM) in MDA–MB–468 cells, whereas it was considerably less active in MCF10A cells (40 μM). In the presence of the CYP1 inhibitor acacetin, the conversion of nobiletin to NP1 was significantly reduced in MDA–MB–468 cells. Furthermore, a significant increase was noted in the population of the cells at the G1 phase, following treatment with nobiletin (10 μM) for 24 h compared with the control cells treated with DMSO (0.1%) alone (55.9±0.14 vs. 45.6±1.96), whereas the cell cycle of MCF10A cells was not significantly altered under the same treatment conditions. Taken collectively, the results suggest that nobiletin is selectively bioactivated in MDA–MB–468 breast cancer cells via metabolism by the CYP1 family of enzymes.
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    Phytoestrogens as natural prodrugs in cancer prevention - a novel concept
    (Springer, 2008) Arroo, R. R. J.; Androutsopoulos, Vasilis; Patel, A.; Surichan, Somchaiya; Wilsher, N.; Potter, Gerard A.
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    Phytoestrogens as natural prodrugs in cancer prevention: Dietary flavonoids
    (Springer, 2009) Arroo, R. R. J.; Androutsopoulos, Vasilis; Beresford, Kenneth J. M.; Ruparelia, K. C.; Surichan, Somchaiya; Wilsher, N.; Potter, Gerard A.
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    Phytoestrogens as natural prodrugs in cancer prevention: towards a mechanistic model
    (Springer, 2014-06-14) Arroo, R. R. J.; Beresford, Kenneth J. M.; Bhambra, Avninder S.; Boarder, M. R.; Budriesi, Roberta; Cheng, Zhong; Micucci, Matteo; Ruparelia, K. C.; Surichan, Somchaiya; Androutsopoulos, Vasilis
    It has been widely acknowledged that regular consumption of fresh fruits and vegetables is linked with a relatively low incidence of cancers (e.g. breast, cervix, and colon). Notably, dietary polyphenolic compounds that show some structural similarity to human estrogen, e.g. isoflavones, coumestans, lignans, flavones, have been proposed to play a role in cancer prevention. However, at present there is no satisfactory explanation for the cancer preventative properties of this group of compounds. Whereas polyphenolic compounds have been shown to inhibit proliferation of tumour cells in vitro, the results of in vivo tests have mostly been disappointing in this respect. It seems that mammalian phase II detoxification mechanisms make that dietary polyphenols are rapidly and effectively removed from the body, i.e. their concentration in the blood plasma hardly ever reaches levels high enough to have a possible effect on tumour growth. The polymethoxyflavones nobiletin and tangeretin, common constituents of Citrus peel, are better absorbed than polyhydroxy flavonoids, and maintain their biological activity for a longer period of time. The compounds are known to be substrates for the estrogen-converting cytochrome P450 enzymes CYP1A1 and CYP1B1, which are typically overexpressed in a range of tumour tissues. The enzymes catalyse regioselective hydroxylation and dealkylation of the polymethoxyflavones, resulting in reaction products that appear to inhibit cell proliferation via interference with the MAPK/ERK cell signalling pathway.
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    Tangeretin and its metabolite 4'-hydroxytetramethoxyflavone attenuate EGF-stimulated cell cycle progression in hepatocytes; role of inhibition at the level of mTOR/p70S6K
    (Wiley, 2011) Cheng, Z.; Surichan, Somchaiya; Ruparelia, K. C.; Arroo, R. R. J.; Boarder, M. R.
    The mechanisms by which the dietary compound tangeretin has anticancer effects may include acting as a prodrug, forming an antiproliferative product in cancer cells. Here we show that tangeretin also inhibits cell cycle progression in hepatocytes and investigate the role of its primary metabolite 4'-hydroxy-5,6,7,8-tetramethoxyflavone (4'-OH-TMF) in this effect. EXPERIMENTAL APPROACH We used epidermal growth factor (EGF)-stimulated rat hepatocytes, with [(3)H]-thymidine incorporation into DNA as an index of progression to S-phase of the cell cycle, and Western blots for phospho-proteins involved in the cell signalling cascade. KEY RESULTS Incubation of tangeretin with microsomes expressing CYP1A, or with hepatocytes, generated a primary product we identified as 4'-OH-TMF. Low micromolar concentrations of tangeretin or 4'-OH-TMF gave a concentration-dependent inhibition of EGF-stimulated progression to S-phase while having little effect on cell viability. To determine whether time for conversion of tangeretin to an active metabolite would enhance the inhibitory effect we used long pre-incubations; this reduced the inhibitory effect, in parallel with a reduction in the concentration of tangeretin. The EGF-stimulation of hepatocyte cell cycle progression requires signalling through Akt/mTOR/p70S6K kinase cascades. The tangeretin metabolite 4'-OH-TMF selectively inhibited S6K phosphorylation in the absence of significant inhibition of upstream Akt activity, suggesting an effect at the level of mTOR. CONCLUSIONS AND IMPLICATIONS Tangeretin and 4'-OH-TMF both inhibit cell cycle progression in primary hepatocytes. The inhibition of p70S6K phosphorylation by 4'-OH-TMF raises the possibility that inhibition of the mTOR pathway may contribute to the anticancer influence of a flavonoid-rich diet.
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    Tangeretin inhibits the proliferation of human breast cancer cells via CYP1A1/CYP1B1 enzyme induction and CYP1A1/CYP1B1–mediated metabolism to the product 4′ hydroxy tangeretin
    (Elsevier, 2018-04-04) Surichan, Somchaiya; Arroo, R. R. J.; Tsatsakis, A. M.; Androutsopoulos, V. P.
    Tangeretin is a polymethoxylated flavone with multifaceted anticancer activity. In the present study, the metabolism and further antiproliferative activity of tangeretin was evaluated in the CYP1 expressing human breast cancer cell lines MCF7 and MDA–MB–468 and the normal breast cell line MCF10A. Tangeretin was converted to 4ʹ OH tangeretin by recombinant CYP1 enzymes and in MCF7 and MDA–MB–468 cells. This metabolite was absent in MCF10A cells that did not express CYP1 enzymes. Tangeretin exhibited submicromolar IC50 (0.25±0.15 μM) in MDA–MB–468 cells, whereas it was less active in MCF7 cells (13.5±0.8 μM) and completely inactive in MCF10A cells (>100 μM). In MDA–MB–468 cells that were coincubated with the CYP1 inhibitor acacetin, an approximately 70–fold increase was noted in the IC50 (18±1.6 μM) of tangeretin. In the presence of the CYP1 inhibitor acacetin, the conversion of tangeretin to 4ʹ OH tangeretin was significantly reduced in MDA–MB–468 cells (2.55±0.19 μM vs. 6.33±0.12 μM). The mechanism of antiproliferative action involved cell cycle arrest at the G1 phase for MCF7 and MDA–MB–468 cells, whereas the cell cycle of MCF10A cells was unaffected by 10 μM of tangeretin treatment for 24 and/or 48 h. Tangeretin was further shown to induce CYP1 enzyme activity and CYP1A1/CYP1B1 protein expression in MCF7 and MDA–MB–468 cells. Taken collectively, the results suggest that tangeretin inhibits the proliferation of human breast cancer cells via CYP1A1/CYP1B1 enzyme induction and CYP1A1/CYP1B1–mediated metabolism to the product 4ʹ hydroxy tangeretin.