Measurement of pS2 protein in pancreatic cyst fluids - Evidence for a potential role of pS2 protein in the pathogenesis of mucinous cystic tumors

Conclusion. Elevated levels of the growth factor pS2 protein in the cyst fl uids of mucinous cystic tumors correlate with earlier observations using im munohistochemical techniques showing that pS2 protein is expressed by these tumors. The markedly elevated levels of pS2 protein compared to normal pla sma values suggest that this growth factor may be important in the pathogen esis of pancreatic mucinous cystic tumors. Background. Cystic lesions of the pancreas include inflammatory pseudocysts , serous cystadenomas, and mucinous cystic tumors, some of which are malign ant. Previous studies using immunohistochemical techniques have shown that virtually all pancreatic mucinous tumors express pS2 protein. pS2 protein i s a growth factor that is believed to be important in the normal process of inflammation and repair. We measured pS2 protein and other growth factors in pancreatic cyst fluids to assess their potential pathophysiologic and di agnostic significance. Methods. Levels of pS2 protein were measured in 54 pancreatic cyst fluids b y radioimmunoassay. The growth factors, epidermal growth factor (EGF), tran sforming growth factor-cc (TGF-a), and insulin-like growth factors I and II (IGF-I, IGF-II) were measured in 22 cyst fluids using commercial immunoass ays. Results. Mucinous cysts exhibited significantly higher levels of cyst fluid pS2 protein than nonmucinous lesions, including pseudocysts and serous cys tadenomas (median: 78,303 pg/mL; range: 218-361,176 pg/mL vs median: 886 pg /mL; range: 0-14,206 pg/mL; p = 0.0001). The level of pS2 in mucinous tumor s was markedly higher than plasma values (median: 392 pg/mL). Levels of pS2 protein in malignant mucinous lesions tended to be higher than those in be nign mucinous cysts, but this difference was not statistically significant (median: 88,817 vs 64,350 pg/mL; p = 0.159). Levels of other growth factors , including EGF, TGF-alpha, IGF-I, and IGF-II, did not discriminate among t he different cyst types, and the values were within normal plasma ranges.