The calcium-binding protein S100P in normal and malignant human tissues

Seppo Parkkila,Jaromir Pastorek,Henrik O Helin,Pei-Wen Pan,Aoife Ward,Jorma Isola,Silvia Pastorekova,Adriana Gibadulinova,Alejandra Rodriguez Martinez,Ingrid Oveckova

doi:10.1186/1472-6890-8-2

Abstract

BackgroundS100P 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.MethodsWe 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.ResultsAmong 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.ConclusionBased 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.

Highlights

S100P is a Ca2+ binding protein overexpressed in a variety of cancers, and has been considered a potential tumor biomarker
The control MAb showed slightly stronger reactivity in the glands and lamina propria. All these results clearly demonstrated that the 18-9 MAb is specific for S100P protein and approved its use for the immunohistochemical analysis of S100P expression in human tissues (Figs 4 and 5) and carcinomas including breast (Fig. 6A,B), gastric (Fig. 6C), pancreatic (Fig. 6D), ovarian (Fig. 6E,F), prostate, and colon (Fig. 7) tumors
The present immunohistochemical and quantitative RTPCR results demonstrate that S100P protein is widely expressed in both normal and neoplastic tissues

Summary

Introduction

S100P is a Ca2+ binding protein overexpressed in a variety of cancers, and has been considered a potential tumor biomarker. In colon cancer cell lines, expression level of S100P correlated with resistance to chemotherapy [14], and in lung and breast cancer to decreased patient survival [7,15]. Despite these observations, little is still known about the functional role or mechanism of action of S100P. It has been shown that S100P can induce anchorage-independence of tumor cells in vitro and improve tumor growth in a xenograft model These results suggested that S100P functionally participates in the control of the tumorigenic potential in vivo [9]

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Conclusion