Differential occurrence of S100A7 in breast cancer tissues: a proteomic-based investigation.
OBJECTIVE
The present study reports for the first time a large-scale proteomic screening of the occurrence, subcellular localization and relative quantification of the S100A7 protein among a group of 100 patients, clinically grouped for the diagnosis of infiltrating ductal carcinoma (IDC).


METHODS
To this purpose, the methods of differential proteomics, Western blotting, and immunohistochemistry were used.


RESULTS
The identity of two isoforms of the protein was assessed by mass spectrometry and immunologically confirmed. Moreover, we proved by immunocytochemical applications the exclusive localization of the protein within the neoplastic cells. The correlation of S100A7 expression levels with the collective profile of cancer patients' proteomics predicted functional interactions, distinct for the two isoforms. The S100A7b isoform was significantly correlated with specific protein clusters (calcium binding, signaling and cell motion, heat shock and folding) and intercrossing pathways (antioxidant, metabolic and apoptotic pathways), while the more acidic isoform was correlated with a narrow number of proteins mainly unrelated to the b isoform.


CONCLUSIONS
This study is the first proteomic-based report on S100A7 in a large series of IDC patients. The correlation with in silico data may significantly contribute the knowledge of possible pathways for S100A7, providing novel insights into the mechanism of action of this protein. We suggest that each S100A7 isoform is involved in critical phases of the breast cancer growth and progression, probably through interaction with different partner proteins.
Dipartimento Biomedico di Medicina interna e specialistica (Dibimis) sezione Oncologia Sperimentale e Applicazioni Cliniche, Università di Palermo, Italy. patrizia.cancemi@unipa.it
Patrizia
P
Cancemi
Gianluca
G
Di Cara
Nadia Ninfa
NN
Albanese
Francesca
F
Costantini
Maria Rita
MR
Marabeti
Rosa
R
Musso
Ignazio
I
Riili
Carmelo
C
Lupo
Elena
E
Roz
Ida
I
Pucci-Minafra
D000595:Amino Acid Sequence; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000737:chemistry / Q000378:metabolism; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D040901:Proteomics / Q000379:methods*; D015203:Reproducibility of Results; D000075023:S100 Calcium Binding Protein A7; D009418:S100 Proteins / Q000737:chemistry / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D009363:Neoplasm Proteins; D020033:Protein Isoforms; D000075023:S100 Calcium Binding Protein A7; D009418:S100 Proteins; C089242:S100A7 protein, human