APC in the regulation of intestinal crypt fission

The functional effects of APC (adenomatous polyposis coli gene) germ-line mutations on crypt fission and cell proliferation were investigated in the normal intestine of human familial adenomatous polyposis (FAP) and multiple intestinal neoplasia (MIN) mice. Compared with controls, there was a 19-fold increase in the proportion of crypts in fission in FAP colon [95 per cent confidence interval (CI): 11-32, P < 0.0001], and a 75 and 61 per cent increase in MIN colon (95 per cent CI: 1.08-2.82, P < 0.02) and small bowel, respectively (95 per cent CI: 1.31-1.99, P < 0.001). In marked contrast, no significant differences in intra-cryptal epithelial cell proliferation or mitotic distribution were seen. Furthermore, 10.9 per cent of crypts in FAP were in asymmetrical fission as opposed to only 1 per cent in controls (P = 0.001). The largest relative increases in MIN crypt fission were in the colon (proximal and distal colon:190 per cent, P = 0.02 and 83 per cent, P = 0.01), suggesting that Apc mutations exert their maximal influence site-specifically. However, sites with the highest relative increases were also those with the largest eventual tumour sizes, but not the highest polyp counts. Three-dimensional serial section reconstruction analysis corroborated that FAP adenomas enlarge by crypt fission, which was frequently both asymmetrical and atypical. It is proposed that the absence of an increase in intestinal cell division infers that APC regulates intestinal crypt differentiation, specifically through the crypt cycle. This role appears analogous to the control of axis re-duplication in embryonic development, when downstream targets of APC are over-expressed. It is concluded that in vivo, the major defect in pre-neoplastic intestine harbouring APC mutations is elevated rates of crypt fission, and that this is also the mode by which micro-adenomas enlarge.

APC in the regulation of intestinal crypt fission

The functional effects of APC (adenomatous polyposis coli gene) germ-line mutations on crypt fission and cell proliferation were investigated in the normal intestine of human familial adenomatous polyposis (FAP) and multiple intestinal neoplasia (MIN) mice. Compared with controls, there was a 19-fold increase in the proportion of crypts in fission in FAP colon [95 per cent confidence interval (CI): 11-32, P < 0.0001], and a 75 and 61 per cent increase in MIN colon (95 per cent CI: 1.08-2.82, P < 0.02) and small bowel, respectively (95 per cent CI: 1.31-1.99, P < 0.001). In marked contrast, no significant differences in intra-cryptal epithelial cell proliferation or mitotic distribution were seen. Furthermore, 10.9 per cent of crypts in FAP were in asymmetrical fission as opposed to only 1 per cent in controls (P = 0.001). The largest relative increases in MIN crypt fission were in the colon (proximal and distal colon:190 per cent, P = 0.02 and 83 per cent, P = 0.01), suggesting that Apc mutations exert their maximal influence site-specifically. However, sites with the highest relative increases were also those with the largest eventual tumour sizes, but not the highest polyp counts. Three-dimensional serial section reconstruction analysis corroborated that FAP adenomas enlarge by crypt fission, which was frequently both asymmetrical and atypical. It is proposed that the absence of an increase in intestinal cell division infers that APC regulates intestinal crypt differentiation, specifically through the crypt cycle. This role appears analogous to the control of axis re-duplication in embryonic development, when downstream targets of APC are over-expressed. It is concluded that in vivo, the major defect in pre-neoplastic intestine harbouring APC mutations is elevated rates of crypt fission, and that this is also the mode by which micro-adenomas enlarge.

Dietary fat influences on polyp phenotype in multiple intestinal neoplasia mice

Significant differences in colon cancer incidence worldwide have led to the hypothesis that this variation can be explained largely by environmental, notably dietary influences. Although a positive correlation between dietary fat intake and incidence is suggested from some human epidemiological and rodent carcinogenesis studies, a direct association remains contentious. Using a spontaneous mouse tumor model of multiple intestinal neoplasia, we demonstrate that there is a generalized increase in tumor counts, in both the large and small bowel with higher dietary fat [standard (3%) fat versus high (15%) fat diet (mean +/- SD) 1.59 +/- 1.46 vs. 3.85 +/- 2.37 P < 0.001 and 21.36 +/- 7.4 vs. 31.3 +/- 9.7, respectively, P < 0.001]. Increasing dietary fat also increases polyp size in the small bowel. These changes appear independent of total calorific intake as assessed by body weights. Halving the crude fiber intake together with an increase in dietary fat from 3% to 10% did not have as marked an effect on tumor counts as an increase of fat alone to 15%, which also decreased survival (P < 0.05). These results demonstrate that increasing dietary fat intake from weaning can have a significant adverse effect on polyp numbers in mice genetically predisposed to intestinal tumor development. A further understanding of the biology of this interaction may provide novel strategies aimed at both colonic polyp prevention and treatment.

Combined choriocarcinoma and yolk sac tumor arising in Barrett's esophagus

A patient with primary adenocarcinoma with yolk sac and trophoblastic differentiation occurring in Barrett's esophagus is reported. Yolk sac differentiation at this site has not been described previously. The diagnosis of germ cell differentiation initially was suggested by the finding of elevated serum tumor marker levels. The patient experienced disease remission after cytotoxic chemotherapy. Germ cell differentiation may be difficult to identify in small biopsy samples, which may not be representative of the tumor as a whole. The finding of germ cell differentiation defines therapy and predicates for a relatively good prognosis, which is contrast to adenocarcinoma. Because of the significance of germ cell differentiation in the selection of appropriate therapy, immunostaining for germ cell tumor markers is suggested in all patients with adenocarcinoma who are younger than 50 years.

Hormonal management of prostate cancer

In advanced disease, androgen deprivation remains the usual treatment. The completion of current trials is awaited to confirm whether total androgen blockade will prolong survival. To make further advances in treatment the fundamental biology of the prostate cell, benign or malignant, and its relationship to endocrine manipulation, must be understood. This may then lead to an understanding of clonal escape mechanisms in transformed cells and the clinical correlate of escape, relapse.