Korean J Obstet Gynecol.  1999 Aug;42(8):1755-1768.

Expressions of bcl-2 and c-myc Protooncogenes and Their Relationship to the Proliferation and Apoptosis in Uterine Cervical Intraepithelial Neoplasia and Cervical Carcinoma

• Kim BG
• Lee HP

Abstract

bcl-2 prevents cell death from a wide variety of stimuli and provides survival of cells with accumulated genetic alterations and c-myc can promote both cell proliferation and cell death through the transcriptional regulation of target genes. Although several studies have been reported on the expression of bcl-2 or c-myc separately, little has been known about the role of coexpression of bcl-2 and c-myc to cell proliferation and apoptosis, as well as the frequency of these coexpression in cervical cancer specimens. In this study, we have examined the expression of bcl-2 and c-myc in cervical cancer specimens and cervical intraepithelial neoplasia(CIN) to determine the role of coexpression of bcl-2 and c-myc during progression into cervical cancer. Proteins and transcripts of bcl-2 and c-myc were evaluated by immunohistochemistry in 60 clinical specimens(20 cervical cancer, 30 CIN, and 10 normal cervix). In addtion, we evaluated kinetic indices of cell proliferation and apoptosis simultaneously. The cell proliferation index was determined by detection of the Ki- 67 in immunohistochemistry. Apoptotic index was determined by the detection of apoptotic cells with TUNEL staining. Medical records including pathologic reports were reviewed. Overexpression of bcl-2 and c-myc was identified in 7(35%) and 10(50%) of 20 cervical cancer specimens respectively, but none in normal cervix and CIN samples. In addition, coexpression of bcl-2 and c-myc was found in 5(25%) of 20 cervical cancer specimens. The cell proliferation index increased with progression from normal to CIN and invasive cancer(normal cervix, 10.2; CIN 1, 24.1; CIN 2/3 59.7; cervical cancer, 71.2; p <0.01). The apoptotic index also increased with grade of lesions(normal cervix, 0; CIN 1, 0.33; CIN 2/3, 1.85; cervical cancer, 3.89; p <0.01) and showed a significant correlation with proliferation index(r=0.7451, p=0.0002). However, there was no significant difference in apoptotic index between bcl-2 positive and bcl-2 negative group in cervical cancer(p=0.4765). In addition, there was also no significant difference in cell proliferation between c-myc positive and c-myc negative group(p=0.6891). Furthermore, there was no significant difference in cell proliferation and apoptosis between bcl-2 and c-myc positive group and others in cervical cancer(p=0.6311 and p=0.7600 respectively). The well-known clinicopathologic parameters, including tumor diameter, FIGO clinical stage, lymph node metastasis, did not correlate with simultanuos positive immunoreactivity for bcl-2 and c-myc proteins in cervical cancer. In conclusion, the cell proliferation and apoptosis increase with increasing lesion grade of cervical neoplasia and apoptosis correlates with cell proliferation. In addition, overexpression of bcl-2 and/or c-myc may be genetic alteration found only in cervical cancer and may not play a role in the development and progression of CIN. However, neither bcl-2 nor c-myc immunoreactivity correlated with the proliferation index or apoptotic index. These results suggest that other factors may also play a role in controlling the cell proliferation and apoptosis of cervical cancer.

Keyword

Cervical cancer; Cervical intraepithelial neoplasia; bcl-2; c-myc; Ki-67; Apoptosis

MeSH Terms

Apoptosis*
Cell Death
Cell Proliferation
Cervical Intraepithelial Neoplasia*
Cervix Uteri
Female
Immunohistochemistry
In Situ Nick-End Labeling
Lymph Nodes
Medical Records
Neoplasm Metastasis
Proto-Oncogene Proteins c-myc
Uterine Cervical Neoplasms
Proto-Oncogene Proteins c-myc