Salvia officinalis L. exerts oncostatic effects in rodent and in vitro models of breast carcinoma

Abstract

<b>Introduction:</b> Based on extensive data from oncology research, the use of phytochemicals or plant-based nutraceuticals is considered an innovative tool for cancer management. This research aimed to analyze the oncostatic properties of <i>Salvia officinalis</i> L. <i>[Lamiaceae; Salviae officinalis herba]</i> using animal and <i>in vitro</i> models of breast carcinoma (BC). <b>Methods:</b> The effects of dietary administered <i>S. officinalis</i> in two concentrations (0.1%/SAL 0.1/and 1%/SAL 1/) were assessed in both syngeneic 4T1 mouse and chemically induced rat models of BC. The histopathological and molecular evaluations of rodent carcinoma specimens were performed after the autopsy. Besides, numerous <i>in vitro</i> analyses using two human cancer cell lines were performed. <b>Results and Conclusion:</b> The dominant metabolites found in <i>S. officinalis</i> propylene glycol extract (SPGE) were representatives of phenolics, specifically rosmarinic, protocatechuic, and salicylic acids. Furthermore, the occurrence of triterpenoids ursolic and oleanolic acid was proved in SPGE. In a mouse model, a non-significant tumor volume decrease after S. <i>officinalis</i> treatment was associated with a significant reduction in the mitotic activity index of 4T1 tumors by 37.5% (SAL 0.1) and 31.5% (SAL 1) vs. controls (set as a blank group with not applied salvia in the diet). In addition, salvia at higher doses significantly decreased necrosis/whole tumor area ratio by 46% when compared to control tumor samples. In a rat chemoprevention study, <i>S. officinalis</i> at a higher dose significantly lengthened the latency of tumors by 8.5 days and significantly improved the high/low-grade carcinomas ratio vs. controls in both doses. Analyses of the mechanisms of anticancer activities of <i>S</i>. <i>officinalis</i> included well-validated prognostic, predictive, and diagnostic biomarkers that are applied in both oncology practice and preclinical investigation. Our assessment <i>in vivo</i> revealed numerous significant changes after a comparison of treated vs. untreated cancer cells. In this regard, we found an overexpression in caspase-3, an increased Bax/Bcl-2 ratio, and a decrease in MDA, ALDH1, and EpCam expression. In addition, salvia reduced TGF-β serum levels in rats (decrease in IL-6 and TNF-α levels were with borderline significance). Evaluation of epigenetic modifications in rat cancer specimens <i>in vivo</i> revealed a decline in the lysine methylations of <i>H3K4m3</i> and an increase in lysine acetylation in <i>H4K16ac</i> levels in treated groups. Salvia decreased the relative levels of oncogenic miR21 and tumor-suppressive miR145 (miR210, miR22, miR34a, and miR155 were not significantly altered). The methylation of <i>ATM</i> and <i>PTEN</i> promoters was decreased after <i>S. officinalis</i> treatment (<i>PITX2, RASSF1</i>, and <i>TIMP3</i> promoters were not altered). Analyzing plasma metabolomics profile in tumor-bearing rats, we found reduced levels of ketoacids derived from BCAAs after salvia treatment. <i>In vitro</i> analyses revealed significant anti-cancer effects of SPGE extract in MCF-7 and MDA-MB-231 cell lines (cytotoxicity, caspase-3/-7, Bcl-2, Annexin V/PI, cell cycle, BrdU, and mitochondrial membrane potential). Our study demonstrates the significant chemopreventive and treatment effects of salvia haulm using animal or <i>in vitro</i> BC models.