The c-erbB-2 protooncogene is normal cellular gene which is present on chromosome 17 and encodes a protein which has close sequence homology with the epidermal growth factor receptor. Amplification of the c-erbB-2 gene in breast cancer has been
reported
to correlate with poor patient prognosis but not confirmed yet.
Among the breast carcinoma patients who were treated by modified radical mastectomy from 1989 through 1990 at the Department of Surgery, Seoul National University Hospital, forty seven patents whose fresh tumor tissue was available, were
investigated
the correlation of c-derbB-2 gene amplification and estrogen receptor status.
The mean age of the patients was 48.9 years old(48.9*11.5). Histologically, 45 cases were infiltrating ductal carcinoma, 1 cases medullary carcinoma, 1 case mucinous carcinoma. In pathologic staging, 47 cases comprised 5 cases of stage I, 20
cases
stage
II, 19 cases stage III and 3 cases stage IV. Estrogen receptor status was determined by immunohistochemical staining. 15 out of 42 cases(36%) were estrogen receptor positive.
DNA was extracted from the 47 cases of tumor tissue and digested with the restriction endonuclease EcoRI. The digested material was separated by electrophoresis on agarose gels.
Hind-III digested DNA was used as marker DNA. After the agarose gel was transferred to nitrocellulose paper by Southern blotting, hybridization with 32-Plabelled c-erbB-2 cDNA probe was performed.
Human DNA extracts from placenta was used as control DNA. The same degree of signal with control DNA was interpreted as no amplification of gene. C-erbB-2 protooncogene was found to be amplified in 8.5%(4/47) of the tumors.
Correlation of gene amplification with estrogen receptor status was evaluated. All cases with c-erbB-2 amplification was found to be estrogen receptor negative although statistically insignificant.
Correlation with primary tumor size, number of metastatic lymph node, stage of disease was insignificant. But, the fact that all cases with gene amplification were estrogen receptor negative may implicate the usefulness of c-erbB-2 amplification
as
prognostic variables.
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