Expression profiling of apoptosis-related genes along the crypt-villus axis and in Apc mutant adenomas revealed increased expression of two pro-apoptotic Bcl-2 family members in intestinal adenomas, Bok and Bax.
Finally, we found the downstream genes activated by K-ras oncogene, including B-cell CLL/lymphoma 2 (BCL2), Homo sapiens H2A histone family, member Z (H2AFZ), Homo sapiens RAP1B, member of RAS oncogene family (RAP1B), Homo sapiens T-box 19 (TBX19), Homo sapiens E2F transcription factor 4, p107/p130-binding (E2F4) and matrix metallopeptidase 1 (MMP1), of which were overexpressed in most of all examined adenomas.
Apoptosis was also significantly lower in serrated than in tubulovillous adenomas, but higher than in hyperplastic polyps. p53 oncoprotein expression was significantly greater in both serrated and tubulovillous adenomas than in hyperplastic polyps. bcl-2 protein expression was higher only in tubulovillous adenomas.
Because the majority of colon carcinomas are known to overexpress antiapoptotic proteins such as survivin and Bcl-2 and show only limited ability to undergo apoptosis, we hypothesized that the ability of sulindac to cause regression of adenomas and to inhibit colon carcinogenesis is mediated, at least in part, by down-regulation of one or more of these antiapoptotic proteins.
The molecular phenotype, p27(+)Bcl-2(+)Ki-67(-)mdm2(+), was observed in 76%, 29%, and 0% of typical and atypical adenomas and carcinomas, respectively.
56 adenomas (< or = 10 mm) from 39 patients were analysed for APC, CTNNB1 and K-ras mutations, allelic imbalance on 1p and 18q, microsatellite instability and immunohistochemical expression of HLA-DR, BAX, BCL-2 and Ki-67.
The expression of bcl-2 protein was gradually and significantly lost during the progression from moderately dysplastic adenoma to primary CRC (moderate/severe dysplasia: Mann-Whitney U-test, p=0.0001; severe dysplasia/primary CRC: p=0.027), whereas the cellular expression of bcl-2 mRNA was gradually increased during the dysplasia/adenoma-carcinoma neoplastic sequence.
They included 36 cases with adenoma, 33 with low potential malignancy (LPM) and 63 with carcinomas. bcl-2 expression was observed in 14 of 36 cases (39%) with adenoma, five of 33 (15%) with LPM (P< 0.05) and 12 of 63 (19%) with carcinoma (P < 0.05).
Results suggest that modulation of aberrant beta-catenin expression occurs during NSAID-induced regression of intestinal adenomas and that Bcl-2 may confer resistance to these effects.
Of the acidophilic lesions, the majority of foci (28/32, 88%) and adenomas (47/50, 94%) expressed increased bcl-X(L), whereas increased bcl-2 was observed in only 12.5% of acidophilic preneoplastic foci (4/32) and 14% of acidophilic adenomas (7/50).
However, induction of apoptosis, associated with increased p53 protein expression but not with changes in Bcl-2 expression, was only detected in the adenoma derived BH/C1 and AA/C1 cell lines which express wild type p53 activity.
Immuno-histochemical (IHC) staining expression of bcl-2 and Ki67 was retrospectively investigated in a series of 52 colorectal carcinomas and 56 adenomas according to the avidin-biotin-complex method.
Weak p53 expression was in full thickness of dysplastic epithelium. p21 and bcl2 expression in adenoma was higher than in intestinal type of carcinoma.
In general, BCL-2 expression was significantly stronger in the adenoma than in non-neoplastic mucosa and carcinoma, although there was no significant difference of ISTR-labeling between adenoma and carcinoma.
As controls, fetal and adult normal thyroid glands and adenomas were analysed. bcl-2 expression was detected in 74 of 94 cases (78.7 per cent) of WDC, 16 of 19 cases (84.2 per cent) of PDC, and 3 of 22 cases (13.6 per cent) of UC.