title: Eugenol causes melanoma growth suppression through inhibition of E2F1 transcriptional activity.
abstract: Metastatic malignant melanoma is an extremely aggressive cancer, with no currently viable therapy. 4-Allyl-2-methoxyphenol (eugenol) was tested for its ability to inhibit proliferation of melanoma cells. Eugenol but not its isomer, isoeugenol (2-methoxy-4-propenylphenol), was found to be a potent inhibitor of melanoma cell proliferation. In a B16 xenograft study, eugenol treatment produced a significant tumor growth delay (p = 0.0057), an almost 40% decrease in tumor size, and a 19% increase in the median time to end point. More significantly, 50% of the animals in the control group died from metastatic growth, whereas none in the treatment group showed any signs of invasion or metastasis. Eugenol was well tolerated as determined by measurement of bodyweights. Examination of the mechanism of the antiproliferative action of eugenol in the human malignant melanoma cell line, WM1205Lu, showed that it arrests cells in the S phase of the cell cycle. Flow cytometry coupled with biochemical analyses demonstrated that eugenol induced apoptosis. cDNA array analysis showed that eugenol caused deregulation of the E2F family of transcription factors. Transient transfection assays and electrophoretic mobility shift assays showed that eugenol inhibits the transcriptional activity of E2F1. Overexpression of E2F1 restored about 75% of proliferation ability in cultures. These results indicate that deregulation of E2F1 may be a key factor in eugenol-mediated melanoma growth inhibition both in vitro and in vivo. Since the E2F transcription factors provide growth impetus for the continuous proliferation of melanoma cells, these results suggest that eugenol could be developed as an E2F-targeted agent for melanoma treatment.
authors.affiliation: Department of Cancer Causation and Prevention, AMC Cancer Research Center, 1600 Pierce St., Denver, CO 80214, USA. ghoshr@amc.org
authors.forename: Rita
authors.initials: R
authors.lastname: Ghosh
authors.forename: Nagalakshmi
authors.initials: N
authors.lastname: Nadiminty
authors.forename: James E
authors.initials: JE
authors.lastname: Fitzpatrick
authors.forename: William L
authors.initials: WL
authors.lastname: Alworth
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Slaga
authors.forename: Addanki P
authors.initials: AP
authors.lastname: Kumar
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002448:Cell Adhesion; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D005054:Eugenol / Q000494:pharmacology* / Q000627:therapeutic use*; D005260:Female; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D008545:Melanoma / Q000188:drug therapy* / Q000473:pathology*; D051379:Mice; D009362:Neoplasm Metastasis / Q000188:drug therapy; D020411:Oligonucleotide Array Sequence Analysis; D014157:Transcription Factors / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects*; D023041:Xenograft Model Antitumor Assays
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; C493754:E2f1 protein, mouse; D014157:Transcription Factors; D005054:Eugenol