Inhibitory Effect of Human Breast Cancer Cell Proliferation via p21-Mediated G₁ Cell Cycle Arrest by Araliadiol Isolated from Aralia cordata Thunb.

Abstract

A new polyacetylenic compound, araliadiol, was isolated from the leaves of Aralia cordata Thunb. (Araliaceae). The structure of araliadiol was determined to be 3(S),8(R)-pentadeca-1,9(Z)-diene-4,6-diyne-3,8-diol by MS, NMR, IR, and UV spectroscopic analysis as well as Mosher ester reaction. Araliadiol displayed a significant inhibitory effect on the growth of a human breast adenocarcinoma cell line (MCF-7), with an IC₅₀ value for cytotoxicity of 6.41 µg/mL. Cell cycle analysis revealed that the proportion of cells in the G₁ phase of the cell cycle increased in a dose-dependent manner (from 54.7 % to 72.0 %) after 48 h exposure to araliadiol at dosages ranging from 0 to 80 µM. The results suggest that araliadiol inhibits cell cycle progression of MCF-7 at the G₁-S transition. After treatment with araliadiol, phosphorylation of retinoblastoma protein (Rb) in MCF-7 cells was inhibited, accompanied by a decrease in the levels of cyclin D₃ and cyclin-dependent kinase 4 (cdk4) and an increase in the expression of p21^WAF‐1/Cip1. However, the expression of phosphorylated p53 (Ser15) and Chk2 was not altered in MCF-7 cells. These findings indicate that araliadiol exhibits its growth-inhibitory effects on MCF-7 cells through downregulation of cdk4 and cyclin D₃, and upregulation of p21^WAF‐1/Cip1 by a p53-independent mechanism.

Key words

araliadiol - cytotoxicity - cell cycle - G₁ arrest - Aralia cordata - Araliaceae

References

• 1 Lu F Y. Contributions to the dicotyledonous plants of Taiwan.  Quart J Chin Forest. 1976;  9 127-143
• 2 Minto R E, Blacklock B J. Biosynthesis and function of polyacetylenes and allied natural products.  Prog Lipid Res. 2008;  47 233-306
• 3 Matsunaga H, Katano M, Yamamoto H, Fujito H, Mori M, Takata K. Cytotoxic activity of polyacetylene compounds in Panax ginseng C. A. Meyer.  Chem Pharm Bull. 1990;  38 3480-3482
• 4 Yang M C, Seo D S, Choi S U, Park Y H, Lee K R. Polyacetylenes from the roots of cultivated-wild ginseng and their cytotoxicity in vitro.  Arch Pharm Res. 2008;  31 154-159
• 5 Lee S W, Kim K, Rho M C, Chung M Y, Kim Y H, Lee S, Lee H S, Kim Y K. New polyacetylenes, DGAT inhibitors from the roots of Panax ginseng.  Planta Med. 2004;  70 197-200
• 6 Wang C N, Shiao Y J, Kuo Y H, Chen C C, Lin Y L. Inducible nitric oxide synthase inhibitors from Saposhnikovia divaricata and Panax quinquefolium.  Planta Med. 2000;  66 644-647
• 7 Moon J, Yu S J, Kim H S, Sohn J. Induction of G₁ cell cycle arrest and p 27^KIP1 increase by panaxydol isolated from Panax ginseng.  Biochem Pharmacol. 2000;  59 1109-1116
• 8 Kim J Y, Lee K W, Kim S H, Wee J J, Kim Y S, Lee H J. Inhibitory effect of tumor cell proliferation and induction of G₂/M cell cycle arrest by panaxytriol.  Planta Med. 2002;  68 119-122
• 9 Morgan D O. Principles of CDK regulation.  Nature. 1995;  374 131-134
• 10 Pavletich N P. Mechanisms of cyclin-dependent kinase regulation: structures of Cdks, their cyclin activators, and Cip and INK4 inhibitors.  J Mol Biol. 1999;  287 821-828
• 11 Hoye T R, Jeffrey C S, Shao F. Mosher ester analysis for the determination of absolute configuration of stereogenic (Chiral) carbinol carbons.  Nat Protoc. 2007;  2 2451-2458
• 12 Chang S, Wang S, Wu C L, Shiah S G, Kuo Y H, Chang C J. Cytotoxicity of extractives from Taiwania cryptomerioides heartwood.  Phytochemistry. 2000;  55 227-232
• 13 Jung H J, Min B S, Park J Y, Kim Y H, Lee H K, Bae K H. Gymnasterkoreaynes A–F, cytotoxic polyacetylenes from Gymnaster koraiensis.  J Nat Prod. 2002;  65 897-901
• 14 Seo C S, Li G, Kim C H, Lee C S, Jahng Y, Chang H W, Son J K. Cytotoxic and DNA topoisomerases I and II inhibitory constituents from the roots of Aralia cordata.  Arch Pharm Res. 2007;  30 1404-1409
• 15 Kamb A, Gruis N A, Weaver-Feldhaus J, Liu Q, Harshman K, Tavtigian S V, Stockert E, Day 3rd R S, Johnson B E, Skolnick M H. A cell cycle regulator potentially involved in genesis of many tumor types.  Science. 1994;  264 436-440
• 16 Lukas J, Parry D, Aagaard L, Mann D J, Bartkova J, Strauss M, Peters G, Bartek J. Retinoblastoma-protein-dependent cell-cycle inhibition by the tumour suppressor p16.  Nature. 1995;  375 503-506
• 17 Dyson N. The regulation of E2F by pRB-family proteins.  Genes Dev. 1998;  12 2245-2262
• 18 Kitagawa M, Higashi H, Jung H K, Suzuki-Takahashi I, Ikeda M, Tamai K, Kato J, Segawa K, Yoshida E, Nishimura S, Taya Y. The consensus motif for phosphorylation by cyclin D1-Cdk4 is different from that for phosphorylation by cyclin A/E-Cdk2.  EMBO J. 1996;  15 7060-7069
• 19 Harbour J W, Luo R X, Dei Santi A, Postigo A A, Dean D C. Cdk phosphorylation triggers sequential intramolecular interactions that progressively block Rb functions as cells move through G1.  Cell. 1999;  98 859-869
• 20 LaThangue N B. DRTF1/E2F: an expanding family of heterodimeric transcription factors implicated in cell-cycle control.  Trends Biochem Sci. 1994;  19 108-114
• 21 Nevins J R. E2F: a link between the Rb tumor suppressor protein and viral oncoproteins.  Science. 1992;  258 424-429
• 22 Dulić V, Kaufmann W K, Wilson S, Tlsty T D, Lees E, Harper J W, Elledge S J, Reed S I. p53-dependent inhibition of cyclin-dependent kinase activities in human fibroblasts during radiation-induced G1 arrest.  Cell. 1994;  76 1013-1023
• 23 el-Deiry W S, Tokino T, Velculescu V E, Levy D B, Parsons R, Trent J M, Lin D, Mercer W E, Kinzler K W, Vogelstein B. WAF1, a potential mediator of p 53 tumor suppression.  Cell. 1993;  75 817-825
• 24 Jiang H, Lin J, Su Z Z, Collart F R, Huberman E, Fisher P B. Induction of differentiation in human promyelocytic HL-60 leukemia cells activates p21, WAF1/CIP1, expression in the absence of p53.  Oncogene. 1994;  9 3397-3406
• 25 Macleod K F, Sherry N, Hannon G, Beach D, Tokino T, Kinzler K, Vogelstein B, Jacks T. p53-dependent and independent expression of p21 during cell growth, differentiation, and DNA damage.  Genes Dev. 1995;  9 935-944
• 26 Sancar A, Lindsey-Boltz L A, Unsal-Kaçmaz K, Linn S. Molecular mechanisms of mammalian DNA repair and the DNA damage checkpoints.  Annu Rev Biochem. 2004;  73 39-85