Expression of small breast epithelial mucin (SBEM) protein in tissue microarrays (TMAs) of primary invasive breast cancers.
OBJECTIVE
Small breast epithelial mucin (SBEM) is a recently described gene product that shows promise as a new breast biomarker. The aim was to investigate for the first time SBEM protein expression in a large cohort (n = 300) of invasive breast cancers, its relationship to established clinical variables and its association with clinical outcome.


RESULTS
Immunohistochemical analysis was performed on tissue microarrays consisting of 149 oestrogen receptor (ER) alpha- and 151 ERalpha+ breast cancers. Overall, 18% of tumours were SBEM+ (n = 53/300). However, SBEM protein was more frequently observed in ER- (22%) than in ER+ cancers (13%; P = 0.049). A significant association with psoriasin/S100A7 expression (P < or = 0.0001) was observed in the entire cohort. SBEM was also positively associated with HER-2 (P = 0.046) in ER- cancers, and increased levels of SBEM were strongly associated with higher tumour grade (P = 0.0015). Furthermore, SBEM expression showed a trend towards an association with reduced overall survival and relapse-free survival in the ER+ cohort (P = 0.063 and P = 0.072, respectively).


CONCLUSIONS
Our results suggest that SBEM may identify a unique subset of breast cancers with poor prognosis and may have future implications for therapeutic management of this disease.
Skliris
G P
GP
Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada.
Hubé
F
F
Gheorghiu
I
I
Mutawe
M M
MM
Penner
C
C
Watson
P H
PH
Murphy
L C
LC
Leygue
E
E
Myal
Y
Y
D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D002135:Calcium-Binding Proteins / Q000378:metabolism; D018270:Carcinoma, Ductal, Breast / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D005260:Female; D019085:Fluorescent Antibody Technique, Direct; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008875:Middle Aged; D009077:Mucins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012334:RNA, Neoplasm / Q000032:analysis; D011960:Receptors, Estrogen / Q000378:metabolism; D000075023:S100 Calcium Binding Protein A7; D009418:S100 Proteins; D015996:Survival Rate; D046888:Tissue Array Analysis / Q000379:methods*
D014408:Biomarkers, Tumor; D002135:Calcium-Binding Proteins; C511061:MUCL1 protein, human; D009077:Mucins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D011960:Receptors, Estrogen; D000075023:S100 Calcium Binding Protein A7; D009418:S100 Proteins; C089242:S100A7 protein, human