Effect of the cyclin-dependent kinases inhibitor p27 on resistance of ovarian cancer multicellular spheroids to anticancer chemotherapy.
OBJECTIVE
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.
Xing
Hui
H
Department of Obsterics and Gynecology, Tongji Hospital Affiliated to Tongji Medical School, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, People Republic of China.
Wang
Shixuan
S
Hu
Keqin
K
Tao
Wenming
W
Li
Jing
J
Gao
Qinglai
Q
Yang
Xiaokui
X
Weng
Danhui
D
Lu
Yunpin
Y
Ma
Ding
D
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000032:analysis; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016213:Cyclins / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D018613:Microscopy, Confocal; D016376:Oligonucleotides, Antisense / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018874:Spheroids, Cellular / Q000187:drug effects*; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018797:Cell Cycle Proteins; D016213:Cyclins; D016376:Oligonucleotides, Antisense; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27