Silibinin inhibits colorectal cancer growth by inhibiting tumor cell proliferation and angiogenesis

Cancer Res. 2008 Mar 15;68(6):2043-50. doi: 10.1158/0008-5472.CAN-07-6247.


Herein, for the first time, we investigated in vivo efficacy and associated molecular biomarkers and mechanisms of a chemopreventive agent, silibinin, against human colorectal carcinoma (CRC) HT29 xenograft growth. Nude mice were implanted with HT29 cells and fed with vehicle (carboxymethyl cellulose or phosphatidylcholine) or 200 mg/kg/d dose of silibinin or 100 and 200 mg/kg/d doses of silybin-phytosome (5 days per week) for 32 days. Silibinin inhibited tumor growth that accounted for 48% (P = 0.002) decrease in tumor volume and 42% (P = 0.012) decrease in tumor weight at the end of the experiment without any adverse health effect. A stronger antitumor efficacy was observed with silybin-phytosome preparation. Silibinin decreased proliferation index by 40% (P < 0.001), increased apoptotic index by approximately 2-fold (P = 0.001), and reduced microvessel density by 36% (P = 0.001) in tumors. Antiproliferative and proapoptotic effects of silibinin were associated with down-regulation of extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt phosphorylation as well as cyclin D1 expression. Antiangiogenic effect of silibinin was coupled with a strong decrease in inducible nitric oxide synthase (NOS) and NOS3, cyclooxygenase-1 (COX-1) and COX-2, and hypoxia-inducing factor-1 alpha (HIF-1 alpha) and vascular endothelial growth factor (VEGF). These findings suggest in vivo antitumor efficacy of silibinin against CRC involving its antiproliferative, proapoptotic, and antiangiogenic activities. The inhibition of ERK1/2 and Akt signaling may account for antiproliferative and proapoptotic effects, whereas down-regulation of NOS, COX, HIF-1 alpha, and VEGF expression could lead to antiangiogenic effect of silibinin against CRC. Overall, potential use of silibinin against human CRC could be suggested.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Antioxidants / pharmacology
  • Apoptosis / drug effects
  • Cell Growth Processes / drug effects
  • Colorectal Neoplasms / blood supply
  • Colorectal Neoplasms / drug therapy*
  • Colorectal Neoplasms / metabolism
  • Colorectal Neoplasms / pathology
  • Cyclin D1 / biosynthesis
  • Cyclooxygenase 2 / metabolism
  • Enzyme Activation / drug effects
  • HT29 Cells
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Mice, Nude
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Neovascularization, Pathologic / drug therapy
  • Neovascularization, Pathologic / metabolism
  • Neovascularization, Pathologic / pathology
  • Nitric Oxide Synthase Type II / metabolism
  • Nitric Oxide Synthase Type III / metabolism
  • Oncogene Protein v-akt / metabolism
  • Silybin
  • Silymarin / pharmacology
  • Vascular Endothelial Growth Factor A / biosynthesis
  • Xenograft Model Antitumor Assays


  • Antioxidants
  • HIF1A protein, human
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Silymarin
  • Vascular Endothelial Growth Factor A
  • Cyclin D1
  • Silybin
  • Nitric Oxide Synthase Type II
  • Nitric Oxide Synthase Type III
  • Cyclooxygenase 2
  • Oncogene Protein v-akt
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3