Published in:
01-08-2003 | Original Paper
Different apoptotic activity and p21WAF1/CIP1, but not p27Kip1, expression in serrated adenomas as compared with traditional adenomas and hyperplastic polyps of the colorectum
Published in: Journal of Cancer Research and Clinical Oncology | Issue 8/2003
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Purpose
Serrated adenomas (SAs), which include a wide spectrum of lesions, can be broadly divided into two subtypes: type I, closely mimicking hyperplastic polyps (HPs), and type II, unequivocal adenomatous tumor. Our preliminary findings showed clinicopathologic differences between them. The present study was conducted to investigate apoptotic activity and expression of the cell cycle regulator proteins p21WAF1/CIP1 and p27Kip1 in type I and II SAs, as compared with traditional adenomas (TAs) and HPs.
Methods
Apoptotic activity was estimated in hematoxylin-eosin stained specimens, and p21WAF1/CIP1 or p27Kip1 immunoreactivity was determined in 62 SAs (19 type I and 43 type II), 50 TAs and 19 HPs. The numbers (percentages) of apoptotic or immunoreactive cells were counted per 1,000 epithelial cells in equally separated crypt zones (upper, middle, and lower thirds).
Results
The apoptotic activity in the middle, but not the upper or lower crypt zone was higher in type II SAs (median 0.2%, interquartile range 0.1–0.5%) than in HPs (0.1%, 0.1–0.2%, P<0.01), whereas it was lower in type I SAs (0.2%, 0.1–0.3%) than in TAs (0.5%, 0.2–0.6%, P<0.001). P21WAF1/CIP1 expression in the lower crypt zone was higher in both type I and type II SAs (19.8%, 7.0–33.2% and 20.4%, 3.9–47.8%, P<0.0001) than in TAs (1.2%, 0.6–5.2%), and a similar tendency was also observed for the middle crypt zone. p27Kip1 expression did not vary among the groups.
Conclusions
The differences in apoptotic activity and p21WAF1/CIP1 expression between SAs and TAs or HPs indicate that SA should be considered as a distinct subtype of colorectal neoplasm. The two subtypes of SA do not differ in these parameters despite specific clinicopathological features.