Abstract
The precise regulation and maintenance of balance between cell proliferation and cell death in multicellular organisms is critical for tissue homeostasis. bcl-2 initiates a new gene family involved in the regulation of cell death and survival without affecting cell proliferation. Expression of Bcl-2 has been reported in a wide range of hematopoletic cells, nonneoplastic epithelia (both hormone-responsive and nonresponsive), and epithelial malignancies. Although the major group of epithelial cells expressing Bcl-2 protein are in the proliferating zones, expression is not directly related to cell proliferation. Bcl2 is also associated with stem cells committed to differentiation and morphogenesis. The survival advantage provided by Bcl-2 prolongs the life span of epithelial cells with differentiation potential and allows proliferation, differentiation, and morphogenesis to proceed. The gene expression in hormone-responsive organs may contribute to the sustained life of those terminally differentiated epithelial cells and a decrease in Bcl-2 levels leads to cell death by apoptosis. Overexpression of bcl-2 protects epithelial cells from death, but it is neither able to immortalize normal cells, nor to cause tumorigenic transformation of immortalized epithelial cells. Heterogeneous expression of Bcl-2 in epithelial malignancies suggests that the gene is differentially regulated. Furthermore, its expression in association with precancerous lesions suggests a role in the early stage of tumorigenesis. The effects of Bcl-2 expression on sensitivity of epithelial cells to drug, radiation, and hormone therapies vary depending on the type of tumor. Expression of Bcl-2 is associated with resistance to hormone therapy and recurrence in prostate carcinomas, whereas in lung and breast carcinomas it is associated with a better prognosis. Studies now being performed should clarify the underlying mechanisms of differential gene regulation in different tissues and show the clinical significance of the expression of bcl-2 and other members of the bcl-2 gene family.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
