Weakened spindle checkpoint with reduced BubR1 expression in paclitaxel-resistant ovarian carcinoma cell line SKOV3-TR30.
OBJECTIVE
Paclitaxel sensitivity has recently been associated with the spindle checkpoint. The aim of our study is to investigate the status of spindle checkpoint and the alteration of its major components in phenotype with acquired paclitaxel resistance in ovarian carcinoma.


METHODS
A paclitaxel-resistant ovarian carcinoma cell line, SKOV3-TR30, with the resistant ability of 27-fold greater than its parental cell line, was derived from SKOV3 cell line. The competence of spindle checkpoint and the expression of the major spindle checkpoint proteins (BubR1 and Mad2) in SKOV3-TR30 cells were investigated.


RESULTS
Mitotic index and flow cytometric analysis revealed that SKOV3-TR30 cells were not arrested in M phase in contrast to SKOV3, which showed a clear mitotic arrest in the presence of paclitaxel or nocodazole. The expressions of securin and cyclin B in SKOV3-TR30 cells were significantly lower than those in SKOV3 cells, indicating the premature degradation of APC substrates in SKOV3-TR30 cells in response to spindle damagers. Chromosome spread analysis showed increased rate of premature sister chromatid segregation in SKOV3-TR30 cells. The expression of spindle checkpoint protein BubR1 was evidently lower in SKOV3-TR30 cells than that in SKOV3 cells. However, there was no significant difference in Mad2 expression between SKOV3-TR30 and SKOV3 cells.


CONCLUSIONS
This study demonstrates that weakened spindle checkpoint with reduced expression of BubR1, but not Mad2, is associated with acquired paclitaxel resistance in ovarian carcinoma cells.
Fu
Yunfeng
Y
Department of Gynecologic Oncology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou 310006, China.
Ye
Dafeng
D
Chen
Huaizeng
H
Lu
Weiguo
W
Ye
Feng
F
Xie
Xing
X
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D002135:Calcium-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000096:biosynthesis / Q000235:genetics; D045744:Cell Line, Tumor; D020090:Chromosome Segregation; D019926:Cyclin B / Q000378:metabolism; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D064246:Mad2 Proteins; D009363:Neoplasm Proteins / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D017239:Paclitaxel / Q000494:pharmacology*; D011494:Protein Kinases / Q000096:biosynthesis* / Q000235:genetics; D017346:Protein Serine-Threonine Kinases; D012097:Repressor Proteins / Q000096:biosynthesis / Q000235:genetics; D064249:Securin; D012854:Sister Chromatid Exchange; D008941:Spindle Apparatus / Q000502:physiology*
D000972:Antineoplastic Agents, Phytogenic; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D019926:Cyclin B; C577697:MAD2L1 protein, human; D064246:Mad2 Proteins; D009363:Neoplasm Proteins; D012097:Repressor Proteins; D064249:Securin; C578002:pituitary tumor-transforming protein 1, human; D011494:Protein Kinases; C584277:BUB1 protein, human; C090464:Bub1 spindle checkpoint protein; D017346:Protein Serine-Threonine Kinases; D017239:Paclitaxel