Loss of BCL-2 in the progression of oral cancer is not attributable to mutations.
BACKGROUND
BCL-2 and BAX are important in the regulation of apoptosis. There have been reports of loss of BCL-2 in basal cells of oral epithelial dysplasia (OED) and in oral squamous cell carcinoma (OSCC), and suppression of BAX in poorly differentiated OSCC.


OBJECTIVE
To investigate whether loss of BCL-2 in OED and OSCC, and of BAX in poorly differentiated OSCC could be attributed to BCL-2 and BAX mutations.


METHODS
Immunohistochemistry and in situ hybridisation were used to confirm BCL-2 and BAX expression. DNA was extracted from archival samples of OED (n = 22) and OSCC (n = 28). The connective tissue part from each section was collected separately and used as the normal reference.


RESULTS
No mutations were detected in BCL-2 or BAX that could explain their aberrant expression at the mRNA and protein levels in OED and OSCC. The reported A/G polymorphism at codon 7 of BCL-2 was detected in 18 of 50 samples and a novel C/T polymorphism at codon 100 was detected in three of 50 samples.


CONCLUSIONS
No mutations were found that could explain loss of BCL-2 in oral dysplasia and carcinoma. An unreported C/T polymorphism in BCL-2 was detected. Downregulation of BCL-2 in OED and OSCC may be the result of transcriptional regulation.
Loro
L L
LL
Department of Odontology-Oral Pathology and Forensic Odontology, Haukeland University Hospital, N5021 Bergen, Norway.
Johannessen
A C
AC
Vintermyr
O K
OK
D001483:Base Sequence; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000378:metabolism; D002454:Cell Differentiation; D004252:DNA Mutational Analysis / Q000379:methods; D004273:DNA, Neoplasm / Q000235:genetics; D018450:Disease Progression; D015870:Gene Expression; D019254:Genes, bcl-2; D006801:Humans; D009062:Mouth Neoplasms / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D020641:Polymorphism, Single Nucleotide; D011230:Precancerous Conditions / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
C494826:BAX protein, human; D004273:DNA, Neoplasm; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D051028:bcl-2-Associated X Protein