Human breast cancer: genetic alterations in the MET gene region.

OBJECTIVE

to test whether the MET gene at chromosome 7q31, which encodes a receptor protein (tyrosine kinase) related to normal histological differentiation, undergoes structural changes in breast cancer. A previous study reported somatic alterations detected as loss of heterozygosity (LOH) at this locus in breast cancer.

DESIGN

Analysis of DNA from tumours and matched normal tissue by Southern blot hybridization with the metH probe; the tumours were also analysed for estrogen and progesterone receptors, ploidy and S phase, and protein expression of the MET and c-erbB-2 protooncogenes.

PARTICIPANTS

Eighty-two patients with breast cancer.

RESULTS

Fifty-three percent of the patients were informative for polymorphism with the metH marker. Somatic alterations of MET, consisting of LOH, were demonstrated in 22% of women who were informative and had breast cancer. No correlation was found between LOH of MET and conventional prognostic factors, or status for c-erbB-2 proto-oncogene expression. Estrogen-receptor status correlated with progesterone-receptor status, and S phase correlated with ploidy and size of the tumour.

CONCLUSIONS

Somatic alterations of MET, detected as LOH with the metH probe, occur in 22% of informative patients. These alterations do not correlate with the prognostic factors established when the mastectomy is performed. It remains to be determined whether the patients' overall survival and disease-free survival rates are correlated with genetic alteration of MET.