Research
Oncology
Nuclear cyclin B1 is overexpressed in low-malignant-potential ovarian tumors but not in epithelial ovarian cancer

https://doi.org/10.1016/j.ajog.2009.05.021Get rights and content

Objective

To investigate the role of cyclin G1 and cyclin B1 in ovarian tumorigenesis.

Study Design

We examined cyclin B1 and G1 expression in 58 epithelial ovarian cancer, 18 low-malignant-potential ovarian tumors, and 6 normal ovarian epithelium samples using immunohistochemistry. We also examined cyclin G1 and p53 expression in 7 epithelial ovarian cancer cell lines using Western blot analysis.

Results

Nuclear cyclin B1 expression was significantly higher in low-malignant-potential tumors than in normal ovarian epithelium. There was no difference in nuclear or cytoplasmic cyclin B1 or cyclin G1 expression between epithelial ovarian cancer and normal ovarian epithelium. Cyclin G1 and B1 expression was not associated with p53 expression or clinicopathologic features in patients with epithelial ovarian cancer or low-malignant-potential tumors.

Conclusion

Our data demonstrated that nuclear cyclin B1 is overexpressed in low-malignant-potential tumors, which may contribute to the development of low-malignant-potential tumors. Cyclin B1 and G1 may not be suitable targets for epithelial ovarian cancer treatment.

Section snippets

Western blot analysis

We obtained 7 established human EOC cell lines with different sensitivities to cisplatin and p53 mutation status (Figure 1). Thirty-five micrograms of protein extracted from these 7 cell lines was loaded into each lane and fractionated by 10-12% sodium dodecyl sulfate polyacrylamide gel electrophoresis before being transferred to nitrocellulose membrane. The blots were then probed with antibodies against cyclin G1 (sc-7865; Santa Cruz Biotechnology, Santa Cruz, CA), p53 (Ab-12, DO-7;

Cyclin B1, cyclin G1, and p53 expression in EOC, LMP tumors, and NOE

Staining of cyclin B1 was found in the cytoplasm, nuclei, or both. Positive nuclear cyclin B1 staining was significantly higher in the LMP samples than in the NOE and EOC samples (P = .01; P < .001). No difference in nuclear cyclin B1 expression was observed between the NOE and EOC samples (Figure 2). When the serous LMP and EOC samples were analyzed, we found that the serous LMP samples still had significantly higher nuclear cyclin B1 expression than the NOE samples (P = .005). Higher nuclear

Comment

Altered regulation of cell cycle results in uncontrolled cell proliferation, which is the hallmark of cancer.4 Cell cycle progression is governed by a series of cyclins and cyclin-dependent kinases. Cyclin B1 and cyclin G1 are important cyclins in regulating G2/M transition, which is essential for mitosis and cell proliferation. Overexpression of cyclin B1 and cyclin G1 has been indicated in various human tumors, including breast, prostate, and lung cancers.9, 11, 13, 20, 21 However, there are

Acknowledgments

We thank Alyson Todd in the Department of Scientific Publications at M.D. Anderson Cancer Center for editing this manuscript.

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    Cite this article as: Zheng H, Hu W, Deavers MT, et al. Nuclear cyclin B1 is overexpressed in low-malignant-potential ovarian tumors but not in epithelial ovarian cancer. Am J Obstet Gynecol 2009;201:367.e1-6.

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