Abstract 40: Methylated resveratrol analogue DMU-212 undergoes metabolic activation to DMU-214 in ovarian A-2780 and SKOV-3 cancer cells

Abstract

Abstract Resveratrol (3,4',5-trans-trihydroxystilbene) is a naturally occurring phytoalexin which shows a wide spectrum of biological activity. Although the anticancer effects of resveratrol have been revealed, its clinical application is limited because of a low bioavailability and a rapid clearance from the circulation. The structural alteration of the stilbene motif of resveratrol has been found to be a promising strategy for generation of several synthetic analogues with improved pharmacokinetic parameters. The substitution of hydroxyl groups of resveratrol for methoxy groups may increase the molecule stability, making it less susceptible to phase II conjugation reactions in vivo. The structure-activity studies have revealed that introduction of additional methoxy groups resulted in an increased cytotoxic properties of resveratrol analogues. Furthermore, the methoxy groups at positions 3,5- and 3,4,5- of the trihydroxystilbene scaffold have been identified as crucial for pro-apoptotic activity of the compound. To date few reports have demonstrated the antiproliferative effect of DMU-212 (3,4,4',5-tetramethoxystilbene) in transformed fibroblasts, prostate, liver, colon, cervical, breast and ovarian cancer cells. It has been shown that DMU-212 is biotransformed to four metabolites: 3'-hydroxy-3,4,5,4'-tetramethoxystilbene (DMU-214), 4'-hydroxy-3,4,5-trimethoxystilbene (DMU-281), 4-hydroxy-3,5,4'-trimethoxystilbene (DMU-291), and 3-hydroxy-4,5,4'-trimethoxystilbene (DMU-807). However, if these metabolites retain the biological activity of DMU-212 remains unknown. Therefore, we evalueted the cytotoxic activity of these four metabolites of DMU-212 and the induction of apoptosis in ovarian A-2780 and SKOV-3 cancer cell lines. CYP1A1 and CYP1B1 are known to catalyze the conversion of estradiol to 4-hydroxyestradiol. Hence, the compounds such as resveratrol or DMU-212, which are structurally similar to the endogenous oestrogen estradiol, have been suggested to undergo metabolism by these enzymes. Surprisingly, DMU-212 has been shown to entirely inhibit CYP1B1 in ovarian A-2780 cancer cell line. Since CYP1B1 has been suggested to be involved in DMU-212 biotransformation, it can be hypothesised that one or more metabolites of DMU-212 regulate the expression of CYP1B1 by the feedback inhibition. To have an insight into DMU-212 metabolites' role in the expression of isoenzymes of CYP1 family we assessed CYP1A1 and CYP1B1 mRNA and protein levels in metabolites-treated A-2780 and SKOV-3 cancer cells. The inhibitory effect of four metabolites of DMU-212 was investigated in ovarian A-2780 and SKOV-3 cancer cell lines by MTT assays. The induction of apoptosis was assayed by Cell Death Detection ELISAPLUS test, Caspase-Glo® 3/7 luminescent test and flow cytometry analysis. The expression of CYP1A1 and CYP1B1 mRNA and protein levels was investigated by RT-qPCR and Western blott, respectively. From among four metabolites of DMU-212, DMU-214 exhibited the highest cytotoxic activity (IC50 A-2780=13.26±2.11 nM; IC50 SKOV-3=29.21±3.17nM). Furthermore, DMU-214 has been revealed to exert more pronounced inhibitory effects than the prototype compound, DMU-212. In addition, we observed that the stronger cytotoxic activity of DMU-214 evoked its greater pro-apoptotic effect. DMU-214 caused an increase in nucleosomes level in A-2780 and SKOV-3 cells, EF= 15.89 and 7.91, respectively. Exposure of either cell line to DMU-214 resulted in a statistically significant decrease in CYP1A1 and CYP1B1 mRNA and protein levels as compared to control. We showed for the first time that DMU-212 undergoes metabolic activation to DMU-214 in ovarian A-2780 and SKOV-3 cancer cell lines. Since DMU-214 has been observed to decrease expression of CYP1A1 and CYP1B1 in A-2780 and SKOV-3 cells our results provide a new insight into the concept of their feedback inhibition by the compound tested. Citation Format: Sylwia Borys, Malgorzata Kucinska, Dorota Trzybulska, Mariusz Kaczmarek, Marcin Wierzchowski, Marek Murias, Jadwiga Jodynis-Liebert, Hanna Piotrowska. Methylated resveratrol analogue DMU-212 undergoes metabolic activation to DMU-214 in ovarian A-2780 and SKOV-3 cancer cells. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Integrating Clinical Genomics and Cancer Therapy; Jun 13-16, 2015; Salt Lake City, UT. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(1_Suppl):Abstract nr 40.