Purified salograviolide A isolated from centaurea ainetensis causes growth inhibition and apoptosis in neoplastic epidermal cells.

Many of the best-selling anticancer drugs are plant-derived. We tested for the anticancer properties of extracts isolated from Centaurea ainetensis, a plant species endemic to Lebanon and which is often used in folk medicine. We performed bioassay-guided fractionation of Centaurea ainetensis extracts using a panel of normal and neoplastic murine cells to identify a component that is associated with antitumor activities. Among several compounds that were fractionated, the sesquiterpene lactone, Salograviolide A, was identified and found to exert the most significant growth inhibitory effects on neoplastic cells. At concentrations that were non-cytotoxic to primary keratinocytes, Centaurea ainetensis crude extract and Salograviolide A preferentially inhibited the proliferation of papilloma and squamous cell carcinoma (SCC) cell lines without significantly affecting the growth of normal cells. Flow cytometric analysis of DNA content indicated that the inhibition of cell proliferation by Centaurea ainetensis crude extract and Salograviolide A was due to G0/G1 cell cycle arrest and increased pre-G0/G1, respectively. The increase in pre-G0/G1, and presumably apoptosis induction, in Salograviolide A-treated keratinocytes was confirmed by DNA Hoechst staining. Western blot analysis and electrophoretic mobility shift assay showed that both the crude extract and the isolated molecule differentially modulated key cell cycle and apoptotic regulators as well as NF-kappaB signaling. Salograviolide A-induced growth inhibition in neoplastic cells was mediated by the accumulation of reactive oxygen species (ROS) highlighting a potent oxidant role of this molecule. These studies suggest the potential therapeutic effects of Centaurea ainetensis, and its component, Salograviolide A, against epidermal squamous cell carcinogenesis.

[1]  J. Sundberg,et al.  Characterization of the progressive skin disease and inflammatory cell infiltrate in mice with inhibited NF-kappaB signaling. , 2004, The Journal of investigative dermatology.

[2]  S. Yuspa,et al.  Development of murine epidermal cell lines which contain an activated rasHa oncogene and form papillomas in skin grafts on athymic nude mouse hosts. , 1988, Cancer research.

[3]  A. Gurib-Fakim,et al.  Medicinal plants: traditions of yesterday and drugs of tomorrow. , 2006, Molecular aspects of medicine.

[4]  Han-Ming Shen,et al.  Anti-cancer potential of sesquiterpene lactones: bioactivity and molecular mechanisms. , 2005, Current medicinal chemistry. Anti-cancer agents.

[5]  J. Ha,et al.  Costunolide Triggers Apoptosis in Human Leukemia U937 Cells by Depleting Intracellular Thiols , 2002, Japanese journal of cancer research : Gann.

[6]  John C. Parker,et al.  “This culture” , 1940, Electrical Engineering.

[7]  D. Hochhauser.  Modulation of chemosensitivity through altered expression of cell cycle regulatory genes in cancer. , 1997, Anti-cancer drugs.

[8]  P M Steinert,et al.  Expression of murine epidermal differentiation markers is tightly regulated by restricted extracellular calcium concentrations in vitro , 1989, The Journal of cell biology.

[9]  K. Brand,et al.  Involvement of NF-kappaB signalling in skin physiology and disease. , 2003, Cellular signalling.

[10]  L. Ährlund‐Richter,et al.  Squamous cell carcinomas and increased apoptosis in skin with inhibited Rel/nuclear factor-kappaB signaling. , 1999, Cancer research.

[11]  T. Slaga,et al.  Mouse homologue of HOS (mHOS) is overexpressed in skin tumors and implicated in constitutive activation of NF-κB , 2002, Oncogene.

[12]  Jennifer Y. Zhang,et al.  NF-kappaB blockade and oncogenic Ras trigger invasive human epidermal neoplasia. , 2003, Nature.

[13]  R. Enriz,et al.  Structure-activity relationship in the gastric cytoprotective effect of several sesquiterpene lactones. , 1992, Journal of medicinal chemistry.

[14]  C. Demetzos,et al.  Bioactive sesquiterpene lactones from Centaurea species and their cytotoxic/cytostatic activity against human cell lines in vitro. , 2002, Planta medica.

[15]  Siyuan Zhang,et al.  Critical roles of intracellular thiols and calcium in parthenolide-induced apoptosis in human colorectal cancer cells. , 2004, Cancer letters.

[16]  Michael Karin,et al.  NF-kappaB at the crossroads of life and death. , 2002, Nature immunology.

[17]  S. Yuspa,et al.  The pathogenesis of squamous cell cancer: lessons learned from studies of skin carcinogenesis. , 1998, Journal of dermatological science.

[18]  M. Kulesz-Martin,et al.  Clonal growth of mouse epidermal cells in medium with reduced calcium concentration. , 1981, The Journal of investigative dermatology.

[19]  Shishir Shishodia,et al.  Molecular targets of dietary agents for prevention and therapy of cancer. , 2006, Biochemical pharmacology.

[20]  V. Tešević,et al.  Guaianolides from Centaurea nicolai: antifungal activity. , 1999, Phytochemistry.

[21]  Michael Karin,et al.  IKKβ Couples Hepatocyte Death to Cytokine-Driven Compensatory Proliferation that Promotes Chemical Hepatocarcinogenesis , 2005, Cell.

[22]  N. Darwiche,et al.  Overexpression of retinoic acid receptors alpha and gamma into neoplastic epidermal cells causes retinoic acid-induced growth arrest and apoptosis. , 2001, Carcinogenesis.

[23]  T. Ibuka,et al.  Structure-antimicrobial activity relationships among the sesquiterpene lactones and related compounds , 1977 .

[24]  Xiaodong Wang,et al.  Apaf-1, a Human Protein Homologous to C. elegans CED-4, Participates in Cytochrome c–Dependent Activation of Caspase-3 , 1997, Cell.

[25]  James B. Mitchell,et al.  Nuclear factor-kappaB is an important modulator of the altered gene expression profile and malignant phenotype in squamous cell carcinoma. , 2004, Cancer research.

[26]  M. Valko,et al.  Free radicals, metals and antioxidants in oxidative stress-induced cancer. , 2006, Chemico-biological interactions.

[27]  Y. Surh,et al.  Cancer chemoprevention with dietary phytochemicals , 2003, Nature Reviews Cancer.

[28]  Y. Nobukuni,et al.  Chemopreventive effects of emodin and cassiamin B in mouse skin carcinogenesis. , 2002, Cancer letters.

[29]  S. Yuspa,et al.  Two oncogenes, v-fos and v-ras, cooperate to convert normal keratinocytes to squamous cell carcinoma. , 1990, Proceedings of the National Academy of Sciences of the United States of America.

[30]  Karen Holbrook,et al.  Calcium regulation of growth and differentiation of mouse epidermal cells in culture , 1980, Cell.

[31]  C. Gélinas,et al.  To be, or not to be: NF-κB is the answer – role of Rel/NF-κB in the regulation of apoptosis , 2003, Oncogene.

[32]  N. Darwiche,et al.  Stage‐specific effect of N‐(4‐hydroxyphenyl)retinamide on cell growth in squamous cell carcinogenesis , 2004, Molecular carcinogenesis.

[33]  P. Khavari,et al.  Alterations in NF-kappaB function in transgenic epithelial tissue demonstrate a growth inhibitory role for NF-kappaB. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[34]  E. Williamson,et al.  Synergy and other interactions in phytomedicines. , 2001, Phytomedicine : international journal of phytotherapy and phytopharmacology.

[35]  H. Gali-Muhtasib,et al.  Anti-colon cancer effects of Salograviolide A isolated from Centaurea ainetensis. , 2008, Oncology reports.

[36]  R. Tennant,et al.  Reduced skin tumor development in cyclin D1-deficient mice highlights the oncogenic ras pathway in vivo. , 1998, Genes & development.

[37]  D. Federman,et al.  Skin cancer screening by dermatologists: prevalence and barriers. , 2002, Journal of the American Academy of Dermatology.

[38]  Jing Wen,et al.  Oxidative Stress-mediated Apoptosis , 2002, The Journal of Biological Chemistry.

[39]  G. Courtois,et al.  TNF-mediated inflammatory skin disease in mice with epidermis-specific deletion of IKK2 , 2002, Nature.