Methylation of CpG sites in exon 2 of the bcl-2 gene occurs in colorectal carcinoma.
BACKGROUND
Aberrant bcl-2 expression frequently occurs in colorectal carcinoma. The current study investigated if CpG sites in bcl-2 were methylated in colorectal carcinoma and if methylation correlated with loss of expression of bcl-2 mRNA.


METHODS
Methylation was assessed in 23 matched normal mucosae and colonic carcinomas by Southern blotting with methylation-sensitive enzymes. Expression of bcl-2 mRNA was assessed by Northern blotting.


RESULTS
A SacII site in exon 2 of the bcl-2 gene was methylated in 5 carcinomas, plus an adjacent HpaII sites in 1 tumour. SacII site in the bcl-2 promoter were not methylated. Elevated levels of bcl-2 mRNA were detected in 3 carcinomas, 5 showed decreased expression and 4 were unchanged.


CONCLUSIONS
De novo methylation of CpG sites in exon 2 of the bcl-2 gene occurs during the development of colorectal carcinoma. However, there was no relationship between expression of bc1-2 mRNA and methylation of specific CpG sites.
Babidge
W J
WJ
Department of Surgery, The University of Adelaide, The Queen Elizabeth Hospital, Woodville, South Australia, Australia.
Butler
L M
LM
Burton
M A
MA
Cowled
P A
PA
D015152:Blotting, Northern; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D018899:CpG Islands; D019175:DNA Methylation; D015257:DNA-Cytosine Methylases / Q000378:metabolism; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D005091:Exons; D015972:Gene Expression Regulation, Neoplastic; D019254:Genes, bcl-2 / Q000235:genetics*; D006801:Humans; D009367:Neoplasm Staging; D011401:Promoter Regions, Genetic; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics
D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; C029641:DNA modification methylase HpaII; D015257:DNA-Cytosine Methylases; C035337:CCGCGG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific