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Bcl-2 protooncogene expression in cervical carcinoma cell lines containing inactive p53
X H Liang1, S Mungal, A Ayscue
1Laboratory for Cell Biology, School of Medicine, University of North Carolina at Chapel Hill 27599, USA.
Journal of Cellular Biochemistry
|March 1, 1995
Summary
Bcl-2 protein expression, which inhibits apoptosis, was found in most cervical cancer cell lines without the typical t(14;18) translocation. This suggests a role for Bcl-2 in cervical carcinogenesis, especially when p53 is inactive.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- Bcl-2 protein inhibits apoptosis and is overexpressed in lymphoid malignancies, often associated with the t(14;18) chromosomal translocation.
- Cervical carcinoma is a significant global health concern, and understanding its molecular underpinnings is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the expression and regulation of Bcl-2 in cervical carcinoma cell lines and normal keratinocytes.
- To determine if Bcl-2 expression in cervical cancer is linked to the characteristic t(14;18) chromosomal translocation.
- To explore the relationship between Bcl-2 expression, p53 status, and human papillomavirus (HPV) in cervical carcinogenesis.
Main Methods:
- Western blotting and immunofluorescence microscopy were used to detect Bcl-2 protein expression.
- Southern blot and polymerase chain reaction (PCR) analyses were employed to assess for chromosomal translocations or rearrangements at the Bcl-2 gene's major breakpoint-cluster region (MBR).
- Northern blot and reverse transcriptase (RT)-PCR were utilized to analyze Bcl-2 gene transcription levels.
Main Results:
- Bcl-2 protein was detected in the cytoplasm of 4 out of 5 cervical carcinoma cell lines (HeLa, CaSki, C-33A, HT-3) but not in normal keratinocytes.
- None of the examined cell lines exhibited the t(14;18) chromosomal translocation or MBR rearrangements in the Bcl-2 gene.
- Low levels of Bcl-2 transcription were observed in some cell lines, and RT-PCR confirmed transcription in all lines with detectable Bcl-2 protein.
- All cervical carcinoma cell lines studied possessed inactive p53, either due to mutation or HPV E6 protein interaction.
Conclusions:
- Bcl-2 expression occurs in cervical carcinoma cell lines independently of the t(14;18) chromosomal translocation.
- The presence of Bcl-2 in cervical cancer cells with inactivated p53 suggests that Bcl-2 may confer a survival advantage, potentially contributing to cervical carcinogenesis.
- These findings highlight a novel mechanism of Bcl-2 involvement in cervical cancer development, distinct from its role in lymphoid malignancies.