title: Heterogeneity of Bcl-2 expression in metastatic breast carcinoma.
abstract: Bcl-2 is an antiapoptotic protein that promotes cell survival, but also may block proliferation. In breast cancer, bcl-2 expression correlates with favorable prognosis and estrogen receptor (ER) positivity. However, experimental data have paradoxically suggested that bcl-2 promotes chemoresistance and metastasis. A direct and comprehensive comparison of bcl-2 expression between primary breast carcinomas and paired distant metastases has not been performed. We completed rapid autopsies on 17 patients with archived primary tumors and metastatic breast carcinoma, and created single-patient tissue microarrays containing each patient's primary tumor and matched metastases. Expression of bcl-2, ER, progesterone receptor, and HER-2 in primary tumors and matched metastases were compared by immunohistochemistry. All 11 ER-positive cases showed bcl-2 labeling in the primary tumor, whereas only 3 of 6 ER-negative cases did (P=0.029). In 10 cases, bcl-2 labeling in metastases was similar to that of the primary, although 3 cases showed significant variation among metastases. In six other cases, bcl-2 labeling was lost or significantly diminished in metastases. Five of the latter cases were Luminal A (ER-positive, HER-2-negative) primaries, three of which lost hormone receptors in metastases. Only 1 of 17 cases showed an increase in bcl-2 labeling in metastases compared with the paired primary tumor. In conclusion, bcl-2 is infrequently upregulated in metastatic breast carcinoma. Instead, downregulation of bcl-2 expression may occur in the setting of hormone therapy resistance. Our findings call into question the potential utility of anti-bcl-2 therapy in metastatic breast cancer.
authors.affiliation: Department of Pathology, The Johns Hopkins Hospital, Baltimore, MD 21231, USA.
authors.forename: Andrea Proctor
authors.initials: AP
authors.lastname: Subhawong
authors.forename: Hind
authors.initials: H
authors.lastname: Nassar
authors.forename: Marc K
authors.initials: MK
authors.lastname: Halushka
authors.forename: Peter B
authors.initials: PB
authors.lastname: Illei
authors.forename: Russell
authors.initials: R
authors.lastname: Vang
authors.forename: Pedram
authors.initials: P
authors.lastname: Argani
mesh_terms: D000328:Adult; D000368:Aged; D001344:Autopsy; D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000378:metabolism* / Q000556:secondary; D018275:Carcinoma, Lobular / Q000378:metabolism* / Q000556:secondary; D047628:Estrogen Receptor alpha; D017809:Fatal Outcome; D005260:Female; D006801:Humans; D008875:Middle Aged; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D046888:Tissue Array Analysis
chemical_list: D014408:Biomarkers, Tumor; D047628:Estrogen Receptor alpha; D019253:Proto-Oncogene Proteins c-bcl-2; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone