The calcium-binding protein S100P in normal and malignant human tissues.
BACKGROUND
S100P is a Ca2+ binding protein overexpressed in a variety of cancers, and thus, has been considered a potential tumor biomarker. Very little has been studied about its normal expression and functions.


METHODS
We examined S100P expression in normal human tissues by quantitative reverse transcription polymerase chain reaction and immunohistochemistry. S100P protein expression was also studied in a series of tumors, consisting of 74 ovarian, 11 pancreatic, 56 gastric, 57 colorectal, 89 breast and 193 prostate carcinomas using a novel anti-S100P monoclonal antibody.


RESULTS
Among the normal tissues, the highest S100P mRNA levels were observed in the placenta and esophagus. Moderate signals were also detected in the stomach, duodenum, large intestine, prostate and leukocytes. At the protein level, the highest reactions for S100P were seen in the placenta and stomach. Immunostaining of tumor specimens showed that S100P protein is expressed in all the tumor categories included in the study, being most prevalent in gastric tumors.


CONCLUSIONS
Based on our observations, S100P is widely expressed in both normal and malignant tissues. The high expression in some tumors suggests that it may represent a potential target molecule for future diagnostic and therapeutic applications.
Parkkila
Seppo
S
Institute of Medical Technology, University of Tampere and Tampere University Hospital, Tampere, Finland. seppo.parkkila@uta.fi
Pan
Pei-Wen
PW
Ward
Aoife
A
Gibadulinova
Adriana
A
Oveckova
Ingrid
I
Pastorekova
Silvia
S
Pastorek
Jaromir
J
Martinez
Alejandra Rodriguez
AR
Helin
Henrik O
HO
Isola
Jorma
J