Naturally-occurring mixtures of phytochemicals present in plant foods are proposed to possess tumor-suppressive activities. In this work, we aimed to evaluate the antitumor effects of Thymus vulgaris L. in in vivo and in vitro mammary carcinoma models. Dried T. vulgaris (as haulm) was continuously administered at two concentrations of 0.1% and 1% in the diet in a chemically-induced rat mammary carcinomas model and a syngeneic 4T1 mouse model. After autopsy, histopathological and molecular analyses of rodent mammary carcinomas were performed. In addition, in vitro evaluations using MCF-7 and MDA-MB-231 cells were carried out. In mice, T. vulgaris at both doses reduced the volume of 4T1 tumors by 85% (0.1%) and 84% (1%) compared to the control, respectively. Moreover, treated tumors showed a substantial decrease in necrosis/tumor area ratio and mitotic activity index. In the rat model, T. vulgaris (1%) decreased the tumor frequency by 53% compared to the control. Analysis of the mechanisms of anticancer action included well-described and validated diagnostic and prognostic markers that are used in both clinical approach and preclinical research. In this regard, the analyses of treated rat carcinoma cells showed a CD44 and ALDH1A1 expression decrease and Bax expression increase. Malondialdehyde (MDA) levels and VEGFR-2 expression were decreased in rat carcinomas in both the T. vulgaris treated groups. Regarding the evaluations of epigenetic changes in rat tumors, we found a decrease in the lysine methylation status of H3K4me3 in both treated groups (H3K9m3, H4K20m3, and H4K16ac were not changed); up-regulations of miR22, miR34a, and miR210 expressions (only at higher doses); and significant reductions in the methylation status of four gene promoters—ATM serin/threonine kinase, also known as the NPAT gene (ATM); Ras-association domain family 1, isoform A (RASSF1); phosphatase and tensin homolog (PTEN); and tissue inhibitor of metalloproteinase-3 (TIMP3) (the paired-like homeodomain transcription factor (PITX2) promoter was not changed). In vitro study revealed the antiproliferative and proapoptotic effects of essential oils of T. vulgaris in MCF-7 and MDA-MB-231 cells (analyses of 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS); 5-bromo-20-deoxyuridine (BrdU); cell cycle; annexin V/PI; caspase-3/7; Bcl-2; PARP; and mitochondrial membrane potential). T. vulgaris L. demonstrated significant chemopreventive and therapeutic activities against experimental breast carcinoma.

It is supposed that plant functional foods, rich in phytochemicals, may potentially have preventive effects in carcinogenesis. In this study, the anticancer effects of cloves in the in vivo and in vitro mammary carcinoma model were assessed. Dried flower buds of cloves (CLOs) were used at two concentrations of 0.1% and 1% through diet during 13 weeks after the application of chemocarcinogen. After autopsy, histopathological and immunohistochemical analyses of rat mammary carcinomas were performed. Moreover, in vitro evaluation using MCF‐7 cells was carried out. Dietary administered CLO caused the dose‐dependent decrease in tumour frequency by 47.5% and 58.5% when compared to control. Analysis of carcinoma cells in animals showed bcl‐2, Ki67, VEGFA, CD24 and CD44 expression decrease and Bax, caspase‐3 and ALDH1 expression increase after high‐dose CLO administration. MDA levels were substantially decreased in rat carcinomas in both CLO groups. The evaluation of histone modifications revealed increase in lysine trimethylations and acetylations (H4K20me3, H4K16ac) in carcinomas after CLO administration. TIMP3 promoter methylation levels of CpG3, CpG4, CpG5 islands were altered in treated cancer cells. An increase in total RASSF1A promoter methylation (three CpG sites) in CLO 1 group was found. In vitro studies showed antiproliferative and pro‐apoptotic effects of CLO extract in MCF‐7 cells (analyses of cytotoxicity, Brdu, cell cycle, annexin V/PI, caspase‐7, Bcl‐2 and mitochondrial membrane potential). This study showed a significant anticancer effect of clove buds in the mammary carcinoma model in vivo and in vitro.

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Comprehensive oncology research suggests an important role of phytochemicals or whole plant foods in the modulation of signaling pathways associated with anticancer action. The goal of this study is to assess the anticancer activities of Cinnamomum zeylanicum L. using rat, mouse, and cell line breast carcinoma models. C. zeylanicum (as bark powder) was administered in the diet at two concentrations of 0.1% (w/w) and 1% (w/w) during the whole experiment in chemically induced rat mammary carcinomas and a syngeneic 4T1 mouse model. After autopsy, histopathological and molecular evaluations of mammary gland tumors in rodents were carried out. Moreover, in vitro analyses using MCF-7 and MDA-MB-231 cells were performed. The dominant metabolites present in the tested C. zeylanicum essential oil (with relative content over 1%) were cinnamaldehyde, cinnamaldehyde dimethyl acetal, cinnamyl acetate, eugenol, linalool, eucalyptol, limonene, o-cymol, and α-terpineol. The natural mixture of mentioned molecules demonstrated significant anticancer effects in our study. In the mouse model, C. zeylanicum at a higher dose (1%) significantly decreased tumor volume by 44% when compared to controls. In addition, treated tumors showed a significant dose-dependent decrease in mitotic activity index by 29% (0.1%) and 45.5% (1%) in comparison with the control group. In rats, C. zeylanicum in both doses significantly reduced the tumor incidence by 15.5% and non-significantly suppressed tumor frequency by more than 30% when compared to controls. An evaluation of the mechanism of anticancer action using valid oncological markers showed several positive changes after treatment with C. zeylanicum. Histopathological analysis of treated rat tumor specimens showed a significant decrease in the ratio of high-/low-grade carcinomas compared to controls. In treated rat carcinomas, we found caspase-3 and Bax expression increase. On the other hand, we observed a decrease in Bcl-2, Ki67, VEGF, and CD24 expressions and MDA levels. Assessment of epigenetic changes in rat tumor cells in vivo showed a significant decrease in lysine methylation status of H3K4m3 and H3K9m3 in the high-dose treated group, a dose-dependent increase in H4K16ac levels (H4K20m3 was not changed), down-regulations of miR21 and miR155 in low-dose cinnamon groups (miR22 and miR34a were not modulated), and significant reduction of the methylation status of two out of five gene promoters—ATM and TIMP3 (PITX2, RASSF1, PTEN promoters were not changed). In vitro study confirmed results of animal studies, in that the essential oil of C. zeylanicum displayed significant anticancer efficacy in MCF-7 and MDA-MB-231 cells (using MTS, BrdU, cell cycle, annexin V/PI, caspase-3/7, Bcl-2, PARP, and mitochondrial membrane potential analyses). As a conclusion, C. zeylanicum L. showed chemopreventive and therapeutic activities in animal breast carcinoma models that were also significantly confirmed by mechanistic evaluations in vitro and in vivo.

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