Journal Article

Enhanced growth of colorectal aberrant crypt foci in fasted/refed rats involves changes in TGFβ<sub>1</sub> and p21<sup>CIP</sup> expressions

Giovanna Caderni, Maria-Giulia Perrelli, Fabio Cecchini and Luciana Tessitore

in Carcinogenesis

Volume 23, issue 2, pages 323-327
Published in print February 2002 | ISSN: 0143-3334
Published online February 2002 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/23.2.323
Enhanced growth of colorectal aberrant crypt foci in fasted/refed rats involves changes in TGFβ1 and p21CIP expressions

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We previously demonstrated that fasting/refeeding enhances the initiation phase of liver and colorectal carcinogenesis in rats. The present study was undertaken to establish whether cycles of fasting/refeeding carried out during the promotion phase of carcinogenesis may also affect the formation of aberrant crypt foci (ACF), preneoplastic lesions induced in the colon by azoxymethane (AOM). We were also interested in studying whether this effect might be mediated by changes in the proliferation, apoptosis or expression of TGFβ1 and p21CIP genes in the colon. 44 male Fisher 344 rats were given a single dose of AOM (20 mg/kg s.c.) and one week later, they were exposed to 5 cycles of 4 days fasting followed by 7–10 days of refeeding (refed rats); controls were regularly fed; the rats were killed 2, 8 or 30 days after the last cycle of fasting. Fasting/refeeding caused a dramatic increase in crypt multiplicity when compared with regularly fed rats (AC/ACF was 4.30 ± 1.3 in refed and 2.38 ± 0.4 in regularly fed rats, P < 0.005 means ± SD), while no significant changes were observed in the number of ACF/colon. In the two experimental groups, cell proliferation was higher in ACF than in the surrounding mucosa, but proliferative indexes were higher and the apoptotic index lower in ACF of refed rats compared with regularly fed rats. TGFβ1 expression was higher in the ACF of refed rats than in those of fully fed controls while p21CIP was less expressed in refed rats than in controls. These results suggest that fasting/refeeding is a risk factor for colon cancer and must be taken into account for cancer prevention in humans.

Keywords: ACF, aberrant crypt foci; AOM, azoxymethane; TdT, terminal deoxynucleotidyl transferase

Journal Article.  4753 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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