Cucurbitacin I inhibits tumorigenic ability and enhances radiochemosensitivity in nonsmall cell lung cancer-derived CD133-positive cells

Cancer. 2011 Jul 1;117(13):2970-85. doi: 10.1002/cncr.25869. Epub 2011 Jan 10.


Background: Signal transducer and activator of transcription 3 (STAT3) signaling reportedly promotes tumor malignancy and recurrence in nonsmall cell lung cancer (NSCLC). It was demonstrated previously that the STAT3 pathway maintains the tumorigenicity and therapeutic resistance of malignant tumors as well as cancer stem cells (CSCs). The objective of the current study was to investigate the effect of the strong STAT3 inhibitor, cucurbitacin I, in prominin-1 (CD133)-positive lung cancer cells.

Methods: CD133-positive and CD133-negative NSCLC-derived cells were isolated from 7 patients with NSCLC. CD133-positive NSCLC cells that were treated with or without cucurbitacin I were evaluated for their expression of phosphorylated STAT3 (p-STAT3), tumorigenicity, stemness properties, and resistance to chemotherapeutic drugs and ionizing radiation.

Results: Compared with parental or CD133-negative NSCLC cells, CD133-positive NSCLC cells had greater tumorigenicity, greater radioresistance, and higher expression of octamer-binding transcription factor 4 (Oct-4), Nanog homeobox, and sex-determining region Y, box 2 (Sox2) at high p-STAT3 levels. Cucurbitacin I treatment at 100 nM effectively abrogated STAT3 activation, tumorigenic capacity, sphere formation ability, radioresistance, and chemoresistance in CD133-positive NSCLC cells. Microarray data suggested that cucurbitacin I inhibited the stemness gene signature of CD133-positive NSCLC cells and facilitated the differentiation of CD133-positive NSCLC cells into CD133-negative NSCLC cells. It is noteworthy that 150 nM cucurbitacin I effectively blocked STAT3 signaling and downstream survival targets, such as B-cell chronic lymphocytic leukemia/lymphoma 2 (Bcl-2) and Bcl-2-like 1 (Bcl-xL) expression and induced apoptosis in CD133-positive NSCLC cells. Finally, xenotransplantation experiments revealed that cucurbitacin I plus radiotherapy or chemotherapeutic drugs significantly suppressed tumorigenesis and improved survival in NSCLC-CD133-positive-transplanted, immunocompromised mice.

Conclusions: Targeting STAT3 signaling in CD133-positive NSCLC cells with cucurbitacin I suppressed CSC-like properties and enhanced chemoradiotherapy response. The potential of cucurbitacin I should be verified further in future anti-CSC therapy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AC133 Antigen
  • Aged
  • Animals
  • Antigens, CD / analysis*
  • Apoptosis / drug effects
  • Apoptosis / genetics
  • Blotting, Western
  • Carcinoma, Non-Small-Cell Lung* / drug therapy
  • Carcinoma, Non-Small-Cell Lung* / metabolism
  • Carcinoma, Non-Small-Cell Lung* / pathology
  • Carcinoma, Non-Small-Cell Lung* / radiotherapy
  • Cell Proliferation
  • Cell Separation
  • Drug Resistance, Neoplasm
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Fluorescent Antibody Technique
  • Glycoproteins / analysis*
  • Homeodomain Proteins / biosynthesis
  • Homeodomain Proteins / genetics
  • Humans
  • Lung Neoplasms* / drug therapy
  • Lung Neoplasms* / metabolism
  • Lung Neoplasms* / pathology
  • Lung Neoplasms* / radiotherapy
  • Male
  • Mice
  • Middle Aged
  • Nanog Homeobox Protein
  • Neoplasm Metastasis
  • Neoplasm Transplantation
  • Neoplastic Stem Cells / drug effects*
  • Neoplastic Stem Cells / metabolism
  • Neoplastic Stem Cells / radiation effects
  • Octamer Transcription Factor-3 / biosynthesis
  • Octamer Transcription Factor-3 / genetics
  • Peptides / analysis*
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Radiation Tolerance
  • SOXB1 Transcription Factors / biosynthesis
  • SOXB1 Transcription Factors / genetics
  • STAT3 Transcription Factor / antagonists & inhibitors*
  • STAT3 Transcription Factor / metabolism
  • Signal Transduction / drug effects
  • Triterpenes / pharmacology*
  • Tumor Cells, Cultured
  • bcl-X Protein / genetics


  • AC133 Antigen
  • Antigens, CD
  • Glycoproteins
  • Homeodomain Proteins
  • NANOG protein, human
  • Nanog Homeobox Protein
  • Octamer Transcription Factor-3
  • PROM1 protein, human
  • Peptides
  • Prom1 protein, mouse
  • Proto-Oncogene Proteins c-bcl-2
  • SOX2 protein, human
  • SOXB1 Transcription Factors
  • STAT3 Transcription Factor
  • Triterpenes
  • bcl-X Protein
  • cucurbitacin I