The dried flower buds of clove (Syzygium aromaticum syn Eugenia aromaticum or caryophyllata) belonging to family Myrtaceae are used as a spice worldwide. Clove has been reported to exhibit antimicrobial, anti-viral, anesthetic, insecticidal, anti-convulsant, anti-oxidative and free radical scavenging activities. Eugenol, an active component of essential oil isolated from clove has anti-mutagenic, anti-genotoxic and anti-inflammatory properties. It also restricts DMBA induced skin carcinogenesis in mice. Aqueous extract of clove was effective in reducing the incidence of hyperplasia, dysplasia, and carcinoma in situ in benzo[a]pyrene induced lung carcinoma in mice. However, there are no reports on the effects of clove on human cancers.

In this study we have analyzed the inhibitory effects of the aqueous extract of clove (CAE) on breast cancer using in vitro studies like cell growth, cell migration, three-dimensional capillary tube formation / morphogenesis and apoptosis; and in vivo studies like breast tumor growth in nude mice. Our results indicate that CAE inhibited the growth and proliferation of breast cancer cell lines MDA-MB-231,, and MCF10AEIII 8 cells in a dose dependent manner. In addition, it also reduced cell migration towards Matrigel. CAE also inhibited the enzymatic activity of the Matrix Metalloproteinase-2 (MMP-2), which was analyzed by using two substrates, namely galectin-3 and a fluorescence-quenched substrate MOCAcPLGLA2pr(Dnp)AR-NH2. Cell cycle analysis of cells using flow cytometry after propidium iodide (PI) staining indicated an arrest mainly in S-phase. We also observed an inhibition of DNA synthesis in CAE-treated cells by bromodeoxyuridine (BrdU) incorporation. Expressions of apoptosis-related proteins, poly(ADP-ribose)polymerase (PARP), caspase-3 and caspase-8 remained unchanged after CAE treatment, but CDK2, CDK4, cyclin A and cyclin D2 were down-regulated in treated cells indicating that CAE might affect tumor growth by inducing cell cycle arrest but not apoptosis. There was a 50% reduction in tumor volume in nude mice injected with cells that received CAE extract in their drinking water compared to the control mice. The expression of proliferation, apoptosis, angiogenesis and tumor progression markers (PCNA, TUNEL, p63, CD31, smooth muscle actin, collagen IV, MMP-2 are being investigated in the xenografts. The results suggest that CAE may be explored further as a novel inhibitor of breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5588. doi:10.1158/1538-7445.AM2011-5588