transforming-growth-factor-alpha and Cystadenoma--Serous

Epithelial tumors of the pancreas exhibit a wide spectrum of histologies with varying propensities for metastasis and tissue invasion. The histogenic relationship among these tumor types is not well established; moreover, the specific role of genetic lesions in the progression of these malignancies is largely undefined. Transgenic mice with ectopic expression of transforming growth factor alpha (TGF-alpha) in the pancreatic acinar cells develop tubular metaplasia, a potential premalignant lesion of the pancreatic ductal epithelium. To evaluate the cooperative interactions between TGF-alpha and signature mutations in pancreatic tumor genesis and progression, TGFalpha transgenic mice were crossed onto Ink4a/Arf and/or p53 mutant backgrounds. These compound mutant mice developed a novel pancreatic neoplasm, serous cystadenoma (SCA), presenting as large epithelial tumors bearing conspicuous gross and histological resemblances to their human counterpart. TGFalpha animals heterozygous for both the Ink4a/Arf and the p53 mutation showed a dramatically increased incidence of SCA, indicating synergistic interaction of these alleles. Inactivation of p16(Ink4a) by loss of heterozygosity, intragenic mutation, or promoter hypermethylation was a common feature in these SCAs, and correspondingly, none of the tumors expressed wild-type p16(Ink4a). All tumors sustained loss of p53 or Arf, generally in a mutually exclusive fashion. The tumor incidence data and molecular profiles establish a pathogenic role for the dual inactivation of p16(Ink4a) and p19(Arf)-p53 in the development of SCA in mice, demonstrating that p16(Ink4a) is a murine tumor suppressor. This genetically defined model provides insights into the molecular pathogenesis of SCA and serves as a platform for dissection of cell-specific programs of epithelial tumor suppression.

Topics: Animals; Cyclin-Dependent Kinase Inhibitor p16; Cystadenoma, Serous; Endothelial Growth Factors; Genes, p53; Genes, Tumor Suppressor; Humans; Ligases; Lymphokines; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; Mice, Mutant Strains; Mice, Transgenic; Mutation; Pancreatic Neoplasms; Phenotype; Transforming Growth Factor alpha; Tumor Suppressor Protein p14ARF; Tumor Suppressor Proteins; Ubiquitin-Protein Ligases; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors; Von Hippel-Lindau Tumor Suppressor Protein

Elevated levels of the growth factor pS2 protein in the cyst fluids of mucinous cystic tumors correlate with earlier observations using immunohistochemical techniques showing that pS2 protein is expressed by these tumors. The markedly elevated levels of pS2 protein compared to normal plasma values suggest that this growth factor may be important in the pathogenesis of pancreatic mucinous cystic tumors.. Cystic lesions of the pancreas include inflammatory pseudocysts, serous cystadenomas, and mucinous cystic tumors, some of which are malignant. Previous studies using immunohistochemical techniques have shown that virtually all pancreatic mucinous tumors express pS2 protein. pS2 protein is 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 diagnostic significance.. Levels of pS2 protein were measured in 54 pancreatic cyst fluids by radioimmunoassay. The growth factors, epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), and insulin-like growth factors I and II (IGF-I, IGF-II) were measured in 22 cyst fluids using commercial immunoassays.. Mucinous cysts exhibited significantly higher levels of cyst fluid pS2 protein than nonmucinous lesions, including pseudocysts and serous cystadenomas (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 tumors 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 benign 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 the different cyst types, and the values were within normal plasma ranges.

Topics: Cyst Fluid; Cystadenocarcinoma, Mucinous; Cystadenoma, Mucinous; Cystadenoma, Serous; Epidermal Growth Factor; Humans; Insulin-Like Growth Factor I; Insulin-Like Growth Factor II; Pancreatic Cyst; Pancreatic Neoplasms; Pancreatic Pseudocyst; Proteins; Transforming Growth Factor alpha; Trefoil Factor-1; Tumor Suppressor Proteins