Cell lineage markers in human pancreatic cancer

The normal pancreas consists of three major cell types or lineages that share a common embryologic origin from pluripotent endodermal precursors. The type of cell that undergoes neoplastic transformation to form a pancreatic carcinoma is controversial and may influence the phenotype and biologic behavior of the tumor. In this study, immunohistologic techniques were used to determine the cell lineage differentiation expressed in 29 primary exocrine pancreatic adenocarcinomas, five metastatic exocrine pancreatic adenocarcinomas, and five islet cell neoplasma. Specimens of normal pancreas and chronic pancreatitis were used for comparison. The cell lineage markers consisted of monoclonal and polyclonal antibodies against trypsin and lipase (acinar cells); secretory component, carbonic anhydrase II, and pancreatic cancer mucin SPan-1 (ductal cells); and chromogranin-A and somatostatin (islet cells). The expression of carcinoembryonic antigen (CEA) and lysozyme were also determined. This collection of markers allowed the differentiation between acinar, ductal, and islet cells of normal pancreas and chronic pancreatitis specimens. The expression of cell lineage markers in islet cell tumors was homogeneous and restricted to chromogranin-A. In contrast, the expression of these markers in primary and metastatic exocrine pancreatic adenocarcinomas was variable. Reactivity with monoclonal anti-CEA was absent in normal pancreas, and was present in 83% of chronic pancreatitis specimens as well as 90% of exocrine pancreatic adenocarcinomas. In addition, lysozyme reactivity was absent in normal pancreas; however, lysozyme was expressed in one case of chronic pancreatitis, 17 cases of primary carcinoma, and three cases of metastatic carcinoma. These findings support the concept that the original transformed cell type in many pancreatic exocrine carcinomas resemble endodermal "stem cells" that retain the capability of differentiation along more than one cell lineage pathway.     

Histone deacetylase 1 is required for exocrine pancreatic epithelial proliferation in development and cancer

Histone deacetylases (HDACs) play important roles in the epigenetic control of development, and aberrant expression of HDACs has been implicated in human diseases including cancer. Among the mammalian HDACs, HDAC1 has been extensively studied, but its role in exocrine pancreatic morphogenesis and cancer is still poorly understood. The goal of this study is to determine the functional role of HDAC1 in normal development of exocrine pancreas using zebrafish as the model organism as well as in human pancreatic adenocarcinoma. The zebrafish germline loss-of-function mutation hdac1(hi1618) caused impaired cell cycle progression in pancreatic epithelia, resulting in growth arrest and dysmorphogenesis of exocrine pancreas. In human pancreatic adenocarcinoma tissues and cell lines, HDAC1 was expressed at variably elevated levels. RNA interference-induced silencing of HDAC1 diminished proliferation of the cancer cells and cell cycle progression. The proliferative arrest in the developing exocrine pancreas and pancreatic cancer cells was associated with up-regulated expression of the cyclin-dependent kinase inhibitors and the sonic hedgehog signaling components. This study indicates that HDAC1 is required for pancreatic epithelial proliferation in development and cancer. We hypothesize that aberrant expression of HDAC1 modulates the developmental and signaling pathways in exocrine pancreatic epithelia and consequently the genes required for cellular proliferation during development and progression of pancreatic neoplasia.     

Enhanced expression of annexin II in human pancreatic carcinoma cells and primary pancreatic cancers

Annexin II is a calcium and phospholipid binding protein anda substrate for protein-tyrosine kinases. Recent investigationshave revealed involvement of annexin II in DNA synthesis andcell proliferation. Increased levels of annexin II are observedin cancer cells and tissues. To investigate the expression ofannexin II in pancreatic adenocarcinoma cells and primary tumors,we measured the levels of annexin II mRNA and protein in normalhuman pancreas, five established human pancreatic adenocarcinomacell lines, three primary pancreatic cancers and one metastatictumor. All five cell lines examined had 5- to 15-fold higherlevels of annexin II as compared to normal pancreas. Significantelevations (2-to 8-fold) of annexin II expression were observedin the three primary pancreatic tumors and one metastatic tumorexamined. Immunocytochemical analysis indicates that the increasedexpression of annexin II is limited to proliferating ductularadenocarcinoma, and annexin II expression co-localizes withcells that express PCNA. In normal pancreas, annexin II expressionis seen in ductal and ductular cells and no expression is seenin acinar or islet cells. We conclude from these findings thatannexin II has a role in cell proliferation and its regulationis altered in pancreatic cancer.     

Sonic hedgehog promotes desmoplasia in pancreatic cancer

PURPOSE: We investigated the contribution of Sonic hedgehog (SHH) to pancreatic cancer progression. EXPERIMENTAL DESIGN: We expressed SHH in a transformed primary ductal-derived epithelial cell line from the human pancreas, transformed hTert-HPNE (T-HPNE), and evaluated the effects on tumor growth. We also directly inhibited the activity of SHH in vivo by administering a blocking antibody to mice challenged orthotopically with the Capan-2 pancreatic cancer cell line, which is known to express SHH and form moderately differentiated tumors in nude mice. RESULTS: Our data provide evidence that expression of SHH influences tumor growth by contributing to the formation of desmoplasia in pancreatic cancer. We further show that SHH affects the differentiation and motility of human pancreatic stellate cells and fibroblasts. CONCLUSIONS: These data suggest that SHH contributes to the formation of desmoplasia in pancreatic cancer, an important component of the tumor microenvironment.     

非小细胞肺癌中PAX6表达及其对肿瘤细胞增殖与侵袭作用机制研究

背景与目的：转录因子PAX6主要表达于胚胎期,不同肿瘤中PAX6呈现高表达,通过不同的信号通路发挥肿瘤抑制或促进作用。检测PAX6在非小细胞肺癌(non-small cell lung cancer,NSCLC)中的表达,通过RNAi下调其表达,研究PAX6对肿瘤细胞侵袭和增殖力以及cyclin E、p38表达水平的影响。方法：应用蛋白印记检测86例NSCLC肿瘤组织及癌旁配对组织以及2例细胞系中PAX6的表达情况。应用PAX6特异性siRNA序列,转染NSCLC细胞系A549,MTT法、Transwell小室、划痕实验检测转染前后细胞增殖、侵袭和迁移能力的对比。蛋白质印记法(Western blot)检测转染前后cyclin E及p38表达情况。结果：对比癌旁组织及正常人支气管上皮细胞16HBE,PAX6在NSCLC组织及A549细胞系中显著高表达。选取高效siRNA序列转染细胞系后,PAX6表达的下调抑制了肿瘤细胞的增殖及集落形成,G1期细胞比例增加,细胞侵袭及迁移力均下降。PAX6基因敲低细胞cyclin E及p38活性受到抑制,表达下调。结论：PAX6通过调控MAPK通路及cyclin E的表达加速肿瘤细胞的增殖、侵袭及迁移,是潜在的NSCLC诊疗靶点。     

A common epithelial cell surface antigen (EPM-1) on gastrointestinal tumors and in human sera

A common epithelial cell surface marker (EPM-1) was defined by two monoclonal antibodies (Pa-25 and Pa-42), raised against a pancreatic tumor cell line (Capan-1). Both monoclonal antibodies were tested on 49 cultured human cell lines and 244 tissue samples and reacted with all 76 tissue samples of 20 different normal epithelial cell types and with 57 of 63 epithelial tumor tissue samples of nonendocrine origin. Included were eight exocrine pancreatic carcinomas. There the percentage of EPM-1 positive tumor cells correlated with tumor grading. EPM-1 was detectable on the cell surface of cultured human cell lines of the pancreas, liver, colon, and mamma. Some epithelial tumor cell lines did not express EPM-1 on the cell surface, but in the cytoplasm. 100 nonepithelial and epithelial endocrine tissue samples as well as 25 nonepithelial cultured tumor and normal cells were unreactive with monoclonal antibodies Pa-25 and Pa-42. These included cells of neuronal, endocrine, and mesenchymal origin. EPM-1 activity was purified from pancreas tumor cells Capan-1 and from human sera by high-performance liquid chromatography and its molecular weight amounts to about Mr 400,000. EPM-1 was detectable in bronchial, intestinal, and pancreatic secretions and saliva and serum by an enzyme-linked immunosorbent assay test. EPM-1 values were high in the sera of normal individuals, but low or not detectable in most sera (21 of 31) of patients with gastrointestinal tumors. EPM-1 represents a novel differentiation marker for epithelial cell types, which should have a central role in the biology of normal and tumorous epithelial cells.     

Stem cell-like cancer cells in cancer cell lines

Both stem cells and cancer cells are thought to be capable of unlimited proliferation. Moreover, a small number of cancer cells express stem cell markers, including CD133 and ATP-binding cassette transporters, by which the cells can pump out specific fluorescence dyes, such as Hoechst33342, as well as anti-cancer drugs, suggesting that either cancer cells resemble stem cells or cancers contain stem cell-like cancer cells, called "cancer stem cells (CSCs)". Using the common characteristics of tissue-specific stem cells, it was demonstrated that many types of tumors and cancer cell lines contain CSCs, which self-renew, express stem cell markers, and are tumorigenic. It was also shown that CSCs are resistant to anti-cancer drugs and irradiation. Thus CSCs might be a crucial target for the therapy. Because tumors contain CSCs and recruited normal stem cells, both of which contribute to tumorigenesis, it is difficult to separate CSCs from tumors. By contrast, cancer cell lines do not have any contaminating normal stem cells that quickly loose mulitpotentiality and differentiate in normal culture condition, suggesting that cancer cell lines could be an attractive alternative source of cells for CSC research. In this review I summarize the recent progress in CSC research using cancer cell lines.     

Neurofilament and chromogranin expression in normal and neoplastic neuroendocrine cells of the human gastrointestinal tract and pancreas.

To differentiate neuroendocrine (NE) neoplasms arising at different levels of the gut and pancreas, the authors studied the expression of neurofilament (NF) proteins and chromogranin (CR) in normal and neoplastic NE cells of the human gastrointestinal tract (GIT) (14 ileal/jejunal carcinoids, six appendiceal carcinoids, 11 rectal carcinoids) and pancreas (23 islet cell tumors). Among pancreatic islet cell tumors, those with middle molecular weight (NF-M)-positive cells were more abundant than those with high molecular weight (NF-H)-positive cells; nearly all of these tumors expressed CR. Although NF-M was abundantly expressed in greater than 50% of tumor cells in a subset of these tumors, only one of these tumors exhibited diffuse immunoreactivity with NF-H. Among rectal carcinoid tumors, NF-M and NF-H-positive cells were present in approximately the same number of tumors, yet only diffuse immunoreactivity to NF-H could be detected. Chromogranin immunoreactivity in greater than 50% of tumor cells was present in 74% of islet cell tumors, 93% of ileojejunal carcinoids, and 83% of appendiceal carcinoids, but only in a minority of rectal carcinoids (36%). Although ileojejunal carcinoid tumors rarely expressed NF-M and did not express NF-H, diffuse immunoreactivity with CR was present in nearly all of these tumors. None of the appendiceal carcinoid tumors expressed NF-M or NF-H, yet all of these tumors demonstrated immunoreactivity with CR. Neurofilament immunoreactivity was not detected in normal GIT and pancreatic NE cells, whereas CR immunoreactivity was always present. These results suggest that for NE neoplasms of the GIT and pancreas the differential expression of NF subtypes appears to be related to tumor site; and CR is a marker of most GIT and pancreatic NE neoplasms although NF may discriminate subtypes of GIT and pancreatic NE tumors. Neurofilament subtyping may be useful in the evaluation of the origin of NE tumors presenting as metastatic lesions.     

Alpha-fetoprotein-producing pancreatic cancer cells possess cancer stem cell characteristics

We aimed to demonstrate the existence of cancer stem cells in human pancreatic cancer, and to clarify that they are alpha-fetoprotein (AFP) producing cells. Six cell lines derived from human pancreatic cancers were examined, and AsPC-1 and PANC-1 were noted to express AFP. Single cell culture assays and xenotransplantation revealed that the AFP-producing cells had the capacity for self-renewal and differentiation, and that these cells were tumorigenic. Furthermore, they were resistant to anti-cancer agents. The ABCA12 transporter was expressed in the AFP-producing cells at a level more than twice as high as that in the non-AFP-producing cells. The AFP-producing cells were shown to be putative pancreatic cancer stem cells. Furthermore, the expression of ABCA12 appears to be associated with drug resistance.     

Nestin-linked green fluorescent protein transgenic nude mouse for imaging human tumor angiogenesis

We report here a novel transgenic nude mouse for the visualization of human tumor angiogenesis. We have recently shown that the neural stem cell marker nestin is expressed in hair follicle stem cells and blood vessel networks in the skin of C57/B6 transgenic mice with nestin regulatory element-driven green fluorescent protein (ND-GFP). Others have shown ND-GFP is expressed in the brain, pancreas, and testes in these mice. In the present study, the nestin ND-GFP gene was crossed into nude mice on the C57/B6 background to obtain ND-GFP nude mice. ND-GFP was expressed in the brain, spinal cord, pancreas, stomach, esophagus, heart, lung, blood vessels of glomeruli, blood vessels of skeletal muscle, testes, hair follicles, and blood vessel network in the skin of ND-GFP nude mice. Human lung cancer, pancreatic cancer, and colon cancer cell lines as well as a murine melanoma cell line and breast cancer tumor cell line expressing red fluorescent protein were implanted orthotopically, and a red fluorescent protein-expressing human fibrosarcoma was implanted s.c. in the ND-GFP nude mice. These tumors grew extensively in the ND-GFP mice. ND-GFP was highly expressed in proliferating endothelial cells and nascent blood vessels in the growing tumors, visualized by dual-color fluorescence imaging. Results of immunohistochemical staining showed that CD31 was expressed in the ND-GFP-expressing nascent blood vessels. The ND-GFP transgenic nude mouse model enables the visualization of nascent angiogenesis in human and mouse tumor progression. These results suggest that this model is useful for the imaging of the angiogenesis of human as well as rodent tumors and visualization of the efficacy of angiogenetic inhibitors.     

Bioorthogonal labeling cell-surface proteins expressed in pancreatic cancer cells to identify potential diagnostic/therapeutic biomarkers

To develop new diagnostic and therapeutic tools to specifically target pancreatic tumors, it is necessary to identify cell-surface proteins that may serve as potential tumor-specific targets. In this study we used an azido-labeled bioorthogonal chemical reporter to metabolically label N-linked glycoproteins on the surface of pancreatic cancer cell lines to identify potential targets that may be exploited for detection and/or treatment of pancreatic cancer. Labeled glycoproteins were tagged with biotin using click chemistry, purified by streptavidin-coupled magnetic beads, separated by gel electrophoresis, and identified by liquid chromatography-tandem mass spectrometry (MS). MS/MS analysis of peptides from 3 cell lines revealed 954 unique proteins enriched in the azido sugar samples relative to control sugar samples. A comparison of the proteins identified in each sample indicated 20% of these proteins were present in 2 cell lines (193 of 954) and 17 of the proteins were found in all 3 cell lines. Five of the 17 proteins identified in all 3 cell lines have not been previously reported to be expressed in pancreatic cancer; thus indicating that novel cell-surface proteins can be revealed through glycoprotein profiling. Western analysis of one of these glycoproteins, ecto-5′-nucleotidase (NT5E), revealed it is expressed in 8 out of 8 pancreatic cancer cell lines examined. Further, immunohistochemical analysis of human pancreatic tissues indicates NT5E is significantly overexpressed in pancreatic tumors compared to normal pancreas. Thus, we have demonstrated that metabolic labeling with bioorthogonal chemical reporters can be used to selectively enrich and identify novel cell-surface glycoproteins expressed in pancreatic ductal adenocarcinomas.     

Prostate cancer cells with stem cell characteristics reconstitute the original human tumor in vivo

Cancer may arise from a cancer stem/progenitor cell that shares characteristics with its normal counterpart. We report the reconstitution of the original human prostate cancer specimen from epithelial cell lines (termed HPET for human prostate epithelial/hTERT) derived from this sample. These tumors can be described in terms of Gleason score, a classification not applied to any of the transgenic mouse models currently developed to mimic human disease. Immunohistochemical and Western blot analyses indicate that they do not express androgen receptor or p63, similar to that reported for prostate stem cells. These cell lines also express embryonic stem markers (Oct4, Nanog, and Sox2) as well as early progenitor cell markers (CD44 and Nestin) in vitro. Clonally derived HPET cells reconstitute the original human tumor in vivo and differentiate into the three prostate epithelial cell lineages, indicating that they arise from a common stem/progenitor cell. Serial transplantation experiments reconstitute the tumors, suggesting that a fraction of parental or clonally derived HPET cells have self-renewal potential. Thus, this model may enhance our understanding of human tumor development and provide a mechanism for studying cancer stem/progenitor cells in differentiation, tumorigenesis, preclinical testing, and the development of drug resistance.     

Expression of neutral endopeptidase (NEP/CD10) on pancreatic tumor cell lines, pancreatitis and pancreatic tumor tissues

Neutral endopeptidase (NEP/CD10) is a cell surface zinc metalloprotease cleaving peptide bounds on the amino terminus of hydrophobic amino acids and inactivating multiple physiologically active peptides. Loss or decrease in NEP/CD10 expression have been reported in many types of malignancies, but the role of NEP/CD10 in pancreatic carcinoma has not yet been identified. Using real-time RT-PCR, flow cytometry as well as immunohistochemistry, NEP/CD10 expression was quantified in both pancreatic carcinoma cell lines and in tumor specimens obtained from patients with primary pancreatic carcinomas. Three out of 8 pancreatic carcinoma cell lines exhibit heterogeneous NEP/CD10 expression levels: PATU-8988T expressed the highest NEP/CD10 levels, whereas HUP-T4 and HUP-T3 cells showed a moderate to low NEP/CD10 expression. NEP/CD10 immunoreactivity was found in 6 of 24 pancreatic ductal adenocarcinomas, but also in 3 of 6 tissues of patients with chronic pancreatitis. NEP/CD10 expression in pancreatic tumor lesions and cell lines was not associated with tumor grading and staging. Treatment of PATU-8988T cells with the histone deacetylase inhibitors sodium butyrate and valproic acid induced an increase of NEP/CD10 expression. This was accompanied by a reduced cell proliferation rate of PATU-8988T cells, which was increased by the addition of the enzyme activity inhibitors phosphoramidon and thiorphan. Thus, NEP/CD10 is differentially expressed in pancreatic tumors and might be involved in the proliferative activity of pancreatic cancer cells. However, further studies are needed to provide more detailed information of the role of NEP/CD10 under physiological and pathophysiological conditions of the pancreas.     

Developmental aspects of early pancreatic cancer

The specific cell of origin responsible for generating pancreatic intraepithelial neoplasia and pancreatic ductal adenocarcinoma remains unknown. During development, epithelial stem cells within embryonic pancreatic epithelium give riseto mature acinar, ductal, and islet elements. Emerging evidence suggests that cells with precursor potential also exist within adult pancreas, resulting in significant developmental plasticity among both endocrine and exocrine cell types. In this review, the contribution of developmental plasticity in initiating pancreatic metaplasia and neoplasia is considered, and evidence supporting a role for epithelial stem cells in pancreatic cancer is discussed.