Adenylate cyclase-associated protein 1 overexpressed in pancreatic cancers is involved in cancer cell motility

Abstract

Pancreatic cancer has the worst prognosis among cancers due to the difficulty of early diagnosis and its aggressive behavior. To characterize the aggressiveness of pancreatic cancers on gene expression, pancreatic cancer xenografts transplanted into severe combined immunodeficient mice served as a panel for gene-expression profiling. As a result of profiling, the adenylate cyclase-associated protein 1 (CAP1) gene was shown to be overexpressed in all of the xenografts. The expression of CAP1 protein in all 73 cases of pancreatic cancer was recognized by immunohistochemical analyses. The ratio of CAP1-positive tumor cells in clinical specimens was correlated with the presence of lymph node metastasis and neural invasion, and also with the poor prognosis of patients. Immunocytochemical analyses in pancreatic cancer cells demonstrated that CAP1 colocalized to the leading edge of lamellipodia with actin. Knockdown of CAP1 by RNA interference resulted in the reduction of lamellipodium formation, motility, and invasion of pancreatic cancer cells. This is the first report demonstrating the overexpression of CAP1 in pancreatic cancers and suggesting the involvement of CAP1 in the aggressive behavior of pancreatic cancer cells. Pancreatic cancer is a leading cause of cancer death worldwide. 1,2 Only about 20% of pancreatic cancer can be surgically resected with curative intent at the time of diagnosis. 3 Mainly due to the difficulty in early detection and frequent metastatic dissemination, the 5-year survival rate for pancreatic cancer patients remains below 5%. 3,4 Considering that vascular involvement, lymph node metastasis, and neural invasion have been proposed as prognostic factors, 5-7 it seems that metastasis is responsible for the aggressive behavior of pancreatic cancer. Pancreatic cancer appears to acquire genetic aberrations with successive alteration of genes involved in the regulation of cell proliferation. The alterations include activating mutations of the KRAS gene 8,9 that occur early in the stage of pancreatic carcinogenesis, and inactivations by the deletion and mutation of the CDKN2A, 10 TP53, 11 and SMAD4 genes. 12 In addition to cell proliferation, cell motility is one of the factors associated with cancer metastasis; however, no alteration of such genes has been revealed in pancreatic cancer. Therefore, alteration of the expression level of genes by epigenetic or transcriptional manner may be a cue to elucidate the mechanism of cancer metastasis.Recent developments in the technology of human genome research enabled us to obtain genome-wide gene-expression profiles, and vast numbers of marker molecule candidates for pancreatic cancer have been proposed. [13][14][15][16][17][18] In this study, xenografts of clinical specimens orthotopically transplanted into severe combined immunodeficient (SCID) mice 19 were utilized as a panel for gene-expression profiling of pancreatic cancer. Among commonly overexpressed genes in pancreatic cancer xenografts, we further evaluated the adenylate cyclaseassociated pr...

Mammalian Adenylyl Cyclase-associated Protein 1 (CAP1) Regulates Cofilin Function, the Actin Cytoskeleton, and Cell Adhesion

“…The depletion of CAP1 in fibroblasts reduced cell motility (13,25). However, in these cells, CAP1 depletion did not enhance lamellipodia as we observed in HeLa cells.…”

Mammalian CAP (Cyclase-associated protein) in the world of cell migration

“…29 Thus, it was not surprising that CAP1 depletion reduced cell motility in several cell types, including cancer cells. [12][13][14]25 In contrast to the reduced motility in some cell types, CAP1 knockdown in HeLa cells, however, actually stimulated cell motility and invasion. 5 The CAP1-knockdown HeLa cells also had increased lamellipodia, which could explain the observed cell migration phenotype.…”

Upregulation of integrin β4 promotes epithelial–mesenchymal transition and is a novel prognostic marker in pancreatic ductal adenocarcinoma

“…20 For the extraction of phosphoprotein, we used modified RIPA buffer: 50 mM Tris-HCl (pH 7.4), 1% NP40, 0.1% SDS, 150 mM NaCl, 1 mM EDTA, 1 mM Na 3 VO 4 , 50 mM NaF and protease inhibitors.…”

“…20 The target sequences for knockdown of ITGB4 were as follows: siITGB4a, 5 0 -GTCGCTGATGTGATAACCT-3 0 and siITGB4b, 5 0 -GCTACTGTTGGCTGGATAA-3 0 . As a control, negative control small interfering RNA (siRNA) was purchased from Qiagen.…”