Silibinin strongly inhibits the growth kinetics of colon cancer stem cell-enriched spheroids by modulating interleukin 4/6-mediated survival signals

Oncotarget. 2014 Jul 15;5(13):4972-89. doi: 10.18632/oncotarget.2068.

Abstract

Involvement of cancer stem cells (CSC) in initiation, progression, relapse, and therapy-resistance of colorectal cancer (CRC) warrants search for small molecules as 'adjunct-therapy' to target both colon CSC and bulk tumor population. Herein, we assessed the potential of silibinin to eradicate colon CSC together with associated molecular mechanisms. In studies examining how silibinin modulates dynamics of CSC spheroids in terms of its effect on kinetics of CSC spheroids generated in presence of mitogenic and interleukin (IL)-mediated signaling which provides an autocrine/paracrine amplification loop in CRC, silibinin strongly decreased colon CSC pool together with cell survival of bulk tumor cells. Silibinin effect on colon CSC was mediated via blocking of pro-tumorigenic signaling, notably IL-4/-6 signaling that affects CSC population. These silibinin effects were associated with decreased mRNA and protein levels of various CSC-associated transcription factors, signaling molecules and markers. Furthermore, 2D and 3D differentiation assays indicated formation of more differentiated clones by silibinin. These results highlight silibinin potential to interfere with kinetics of CSC pool by shifting CSC cell division to asymmetric type via targeting various signals associated with the survival and multiplication of colon CSC pool. Together, our findings further support clinical usefulness of silibinin in CRC intervention and therapy.

Publication types

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

MeSH terms

  • Antioxidants / pharmacology
  • Cell Line, Tumor
  • Cell Proliferation / drug effects*
  • Cell Survival / drug effects
  • Cell Survival / genetics
  • Colonic Neoplasms / genetics
  • Colonic Neoplasms / metabolism
  • Colonic Neoplasms / pathology
  • Dose-Response Relationship, Drug
  • Gene Expression Regulation, Neoplastic / drug effects
  • HT29 Cells
  • Humans
  • Interleukin-4 / pharmacology*
  • Interleukin-6 / pharmacology*
  • Kinetics
  • Microscopy, Confocal
  • Neoplastic Stem Cells / drug effects*
  • Neoplastic Stem Cells / metabolism
  • Neoplastic Stem Cells / pathology
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / drug effects
  • Signal Transduction / genetics
  • Silybin
  • Silymarin / pharmacology*
  • Spheroids, Cellular / drug effects*
  • Spheroids, Cellular / metabolism
  • Spheroids, Cellular / pathology
  • Transcription Factors / genetics
  • Transcription Factors / metabolism

Substances

  • Antioxidants
  • Interleukin-6
  • Silymarin
  • Transcription Factors
  • Interleukin-4
  • Silybin