Serum amyloid A: a novel biomarker for endometrial cancer.
BACKGROUND
The authors investigated the expression of serum amyloid A (SAA) in endometrial endometrioid carcinoma and evaluated its potential as a serum biomarker.


METHODS
SAA gene and protein expression levels were evaluated in endometrial endometrioid carcinoma and normal endometrial tissues, by real-time polymerase chain reaction (PCR), immunohistochemistry (IHC), and flow cytometry. SAA concentration in 194 serum samples from 50 healthy women, 42 women with benign diseases, and 102 patients including 49 grade 1, 38 grade 2, and 15 grade 3 endometrial endometrioid carcinoma was also studied by a sensitive bead-based immunoassay.


RESULTS
SAA gene expression levels were significantly higher in endometrial endometrioid carcinoma when compared with normal endometrial tissues (mean copy number by real-time PCR = 182 vs 1.9; P = .001). IHC revealed diffuse cytoplasmic SAA protein staining in poorly differentiated endometrial endometrioid carcinoma tissues. High intracellular levels of SAA were identified in primary endometrial endometrioid carcinoma cell lines evaluated by flow cytometry, and SAA was found to be actively secreted in vitro. SAA concentrations (microg/mL) had medians of 6.0 in normal healthy women and 6.0 in patients with benign disease (P = .92). In contrast, SAA values in the serum of endometrial endometrioid carcinoma patients had a median of 23.7, significantly higher than those of the healthy group (P = .001) and benign group (P = .001). Patients harboring G3 endometrial endometrioid carcinoma were found to have SAA concentrations significantly higher than those of G1/G2 patients.


CONCLUSIONS
SAA is not only a liver-secreted protein, but is also an endometrial endometrioid carcinoma cell product. SAA is expressed and actively secreted by G3 endometrial endometrioid carcinoma, and it is present in high concentration in the serum of endometrial endometrioid carcinoma patients. SAA may represent a novel biomarker for endometrial endometrioid carcinoma to monitor disease recurrence and response to therapy.
Cocco
Emiliano
E
Department of Obstetrics, Gynecology, and Reproductive Sciences, Yale University School of Medicine, New Haven, Connecticut 06520-8063, USA.
Bellone
Stefania
S
El-Sahwi
Karim
K
Cargnelutti
Marilisa
M
Buza
Natalia
N
Tavassoli
Fattaneh A
FA
Schwartz
Peter E
PE
Rutherford
Thomas J
TJ
Pecorelli
Sergio
S
Santin
Alessandro D
AD
D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism; D018269:Carcinoma, Endometrioid / Q000097:blood / Q000378:metabolism*; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D016889:Endometrial Neoplasms / Q000097:blood / Q000378:metabolism*; D004717:Endometrium / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D000685:Serum Amyloid A Protein / Q000378:metabolism*
D014408:Biomarkers, Tumor; D012333:RNA, Messenger; D000685:Serum Amyloid A Protein