Effect of the cyclin-dependent kinases inhibitor p27 on resistance of ovarian cancer multicellular spheroids to anticancer chemotherapy

J Cancer Res Clin Oncol. 2005 Aug;131(8):511-9. doi: 10.1007/s00432-005-0677-9. Epub 2005 May 28.


Purpose: A low proliferating fraction in solid tumors limits the effectiveness of cell-cycle-dependent chemotherapeutic agents. To understand the molecular basis of such resistance, we examined the expression of the cyclin-dependent kinases inhibitor p27, and relationship with drug resistance and P-gp expression in ovarian cancer multicellular spheroids.

Methods: We cultured ovarian cancer cells (A2780 and CAOV3) as multicellular spheroids and examined the expression of p27 and P-glycoprotein (P-gp) by western blot, flow cytometry and confocal. We also analyzed the cell-cycle distribution by flow cytometry. In addition, trypan blue exclusion testing and cell apoptosis analysis were used to detect the sensitivity to Taxol.

Results: When transferred from monolayer to three-dimensional culture, a consistent upregulation of p27 protein and P-gp protein was observed in ovarian cancer cell lines. Compared with monolayer cells, there was a significant increase of G0-G1 phase cells and decrease of S and G2-M phase cells in spheroid cells. Aggregates of cells showed higher cell viability than monolayer cells. Antisense oligodeoxynucleotide (ASON) -mediated downregulation of p27 reduced intercellular adhesion, increased cell proliferation, downregulated P-gp expression and sensitized cells to Taxol.

Conclusions: Our results implicate that p27 serves as a regulator of drug resistance in ovarian tumors. ASON-mediated alteration of p27 reverses resistance of ovarian cancer to anticancer agents that are associated with increased sensitivity of ovarian cancer cells to chemotherapeutic agents.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / analysis
  • Antineoplastic Combined Chemotherapy Protocols / pharmacology*
  • Blotting, Western
  • Cell Cycle / drug effects
  • Cell Cycle Proteins / antagonists & inhibitors*
  • Cell Cycle Proteins / metabolism
  • Cyclin-Dependent Kinase Inhibitor p27
  • Cyclins / metabolism*
  • Down-Regulation / drug effects
  • Drug Resistance, Neoplasm / drug effects*
  • Female
  • Flow Cytometry
  • Humans
  • Microscopy, Confocal
  • Oligonucleotides, Antisense / metabolism
  • Ovarian Neoplasms / drug therapy*
  • Ovarian Neoplasms / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Spheroids, Cellular / drug effects*
  • Tumor Cells, Cultured
  • Tumor Suppressor Proteins / antagonists & inhibitors*
  • Tumor Suppressor Proteins / metabolism


  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Cell Cycle Proteins
  • Cyclins
  • Oligonucleotides, Antisense
  • Tumor Suppressor Proteins
  • Cyclin-Dependent Kinase Inhibitor p27