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Increased apoptosis accompanies neoplastic development in the human colorectum
F A Sinicrope1, G Roddey, T J McDonnell
1Departments of Gastrointestinal Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
Summary
Apoptosis, or programmed cell death, and cell proliferation are key in colorectal cancer development. Altered apoptosis rates, particularly a decrease during the adenoma-to-carcinoma transition, are crucial in colorectal carcinogenesis.
Area of Science:
- Oncology
- Cell Biology
- Gastroenterology
Background:
- Neoplastic development is linked to disruptions in the balance between cell proliferation and apoptosis.
- Understanding these processes in colorectal epithelia is crucial for cancer research.
Purpose of the Study:
- To investigate spontaneous apoptotic and proliferative rates in normal, hyperplastic, adenomatous, and malignant colorectal epithelia.
- To analyze the expression of bcl-2 and p53 in relation to these rates during colorectal carcinogenesis.
Main Methods:
- Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay for DNA strand breaks.
- Morphological identification of apoptotic cells in H&E-stained slides.
- Immunohistochemical analysis of cell proliferation, bcl-2, and p53 expression using monoclonal antibodies.
Main Results:
- Normal colonic mucosa showed higher apoptosis in luminal cells versus proliferative zones.
- Neoplastic transformation correlated with increased apoptosis and proliferation rates.
- Apoptosis decreased at the adenoma-to-carcinoma transition, coinciding with mutant p53 expression.
- In carcinomas, elevated mutant p53 and bcl-2 levels were linked to reduced apoptosis.
Conclusions:
- Apoptosis is a critical regulator of growth in normal and neoplastic colorectal tissues.
- Altered apoptosis rates are significant events in colorectal cancer development.
- An imbalance in apoptosis and proliferation in carcinomas may drive tumor growth and progression.