Tumor-dependent increase of serum amino acid levels in breast cancer patients has diagnostic potential and correlates with molecular tumor subtypes.
BACKGROUND
Malignancies induce changes in the levels of serum amino acids (AA), which may offer diagnostic potential. Furthermore, changes in AA levels are associated with immune cell function. In this study, serum AA levels were studied in breast cancer patients versus patients with benign breast lesions.


METHODS
In a prospective study, serum levels of 15 AA were measured by high performance liquid chromatography before and after surgery in 41 breast cancer patients (BrCA) and nine patients with benign breast lesions (healthy donors, HD). Results were analyzed in relation to clinical tumor data and tested against immunological flow cytometry data. Principal component analysis was performed and the accuracy of AA levels as a potential diagnostic tool was tested.


RESULTS
Pre- but not postoperative serum AA levels were increased in BrCA in eight out of 15 AA compared with HD. Serum AA levels were highest in the most aggressive (basal-like) as compared with the least aggressive tumor subtype (luminal A). A principal component (PC1) of all measured AA correlated with a mainly pro-inflammatory immune profile, while a second one (PC2, selectively considering AA preoperatively differing between HD and BrCA) could predict health state with an area under the curve of 0.870.


CONCLUSIONS
Breast cancer shows a tumor-dependent impact on serum AA levels, which varies with intrinsic tumor subtypes and is associated with a pro-inflammatory state. Serum AA levels need further evaluation as a potential diagnostic tool.
Isabel
I
Poschke
Yumeng
Y
Mao
Rolf
R
Kiessling
Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden. janamarit@yahoo.com.
Jana
J
de Boniface
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000596:Amino Acids / Q000097:blood*; D001943:Breast Neoplasms / Q000097:blood* / Q000235:genetics; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D008875:Middle Aged; D025341:Principal Component Analysis; D011446:Prospective Studies; D013050:Spectrometry, Fluorescence
D000596:Amino Acids