Although general characteristics of intraductal papillary mucinous neoplasms (IPMNs) and their delineation from other pancreatic tumors have been well established, several issues regarding their biology and management remain unresolved. It has been noted briefly by us and other authors that there are different types of papillae in IPMNs; however, their frequency, biologic significance, and clinical relevance are unknown. In this study, the association of different papillary patterns with clinical, pathologic, and biologic parameters was studied in 74 IPMNs, and the expression profile of CDX2 (a specific marker and one of the key determinants of intestinal "programming," and a tumor suppressor) was determined immunohistochemically in addition to MUC1 (a marker of an "aggressive" phenotype in pancreatic neoplasia) and MUC2 ("intestinal type mucin," a marker of the "indolent" phenotype, and a tumor suppressor). The patterns of papillae identified and their association with these parameters were as follows: 1) The intestinal-type (Yonezawa's dark-cell type), similar to villous adenomas, was seen in 26 of 74 (35%) cases. The majority harbored carcinoma in situ (85%) or borderline atypia (15%). They tended to be large (mean, 5.5 cm). Most expressed CDX2 (95%) and MUC2 (92%) but not MUC1 (8%). This type was more commonly associated with colloid-type invasion (14 of 16 invasive carcinomas were of colloid type). 2) The pancreatobiliary type, characterized by arborizing papillae lined by cuboidal cells resembling papillary neoplasms of the biliary tract, was present in 22% of the cases. These were mostly graded as carcinoma in situ (94%); they rarely expressed CDX2 (6%) or MUC2 (19%) but often showed MUC1 labeling (44%). This pattern was more commonly associated with the tubular type of invasive carcinoma and had a slight tendency for a more aggressive clinical course. 3) The null type was characterized by abundant apical mucin and basally located nuclei, similar to the gastric foveolar epithelium. Thirty-one percent of IPMNs had this type of papillae, but this pattern was also present in the background of other IPMNs and in the cystic components of most cases as well. Most pure null-type IPMNs were devoid of complexity and consequently classified as adenoma (48%). They tended to be small (mean, 2.6 cm), were often negative for CDX2, MUC1, and MUC2, and were rarely associated with invasive carcinoma. 4) Some IPMNs (12%) exhibited features that were difficult to classify, and 2 cases had a mixture of pancreatobiliary and intestinal types of papillae. In conclusion, IPMNs include pathologically and biologically distinct epithelial patterns. CDX2 and MUC2 expression is relatively specific for the intestinal type papillae, confirming that these IPMNs indeed exhibit intestinal differentiation. Their close association with colloid carcinoma, which also shows consistent MUC2 and CDX2 expression, supports the existence of an intestinal pathway of carcinogenesis. This "metaplastic" pathway may reflect different genetic events in th...

CARP-1, a novel apoptosis inducer, regulates apoptosis signaling by diverse agents, including adriamycin and growth factors. Epidermal growth factor receptor (EGFR)-related protein (ERRP), a panErbB inhibitor, inhibits EGFR and stimulates apoptosis. Treatments of cells with ERRP or Iressa (an EGFR tyrosine kinase inhibitor) results inProgrammed cell death (apoptosis) is essential for the development and maintenance of cellular homeostasis. The pathways regulating apoptosis serve as important targets for many anti-cancer agents currently utilized for treatment of diverse malignancies. Recently, we reported identification of a novel perinuclear protein CARP-1, also known as CCAR1 (1). CARP-1 regulates apoptosis signaling by chemotherapeutic agent adriamycin and by a novel retinoid [3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalene carboxylic acid (CD437). [3-(1-adamantyl)-4-Hydroxyphenyl]-2-naphthalene carboxylic acid belongs to a novel class of apoptogenic adamantyl retinoids that induce growth arrest and stimulate apoptosis in a wide variety of malignant cell types, including breast and prostate cancer and leukemia, by an retinoic acid receptor/retinoid X receptor-independent mechanism (2-4). Expression of CARP-1, on the other hand, induces apoptosis while causing elevated levels of CDKI p21 WAF1CIP1 and inhibiting the expression of a number of cell cycle-regulatory proteins such as c-Myc, cyclin B, and topoisomerase II␣ (1). Whereas it is evident that CARP-1 is an important apoptosis signal transducer, it is unclear how CARP-1-dependent apoptosis is accomplished. Understanding the apoptosis-inducing pathways utilized by CARP-1 will define mechanism(s) of action of agents such as adriamycin. Members of the EGFR 2 family of receptor tyrosine kinases, which includes EGFR, ErbB-2/HER-2, ErbB-3/HER-3, and ErbB-4/HER-4, collectively referred to as EGFRs, serve as critical mediators of the cellular communication network regulating complex biological processes such as growth, differentiation, motility, or death (5, 6). Since deregulated signaling by EGFRs is frequently noted in a variety of human cancers (7-9), interference with growth factor receptor activation and/or with intracellular growth factor-activated signal transduction pathways represents a promising strategy for the development of novel and selective anti-cancer therapies (10 -12). Small molecule inhibitors of EGFR, such as gefitinib (Iressa) and erlotinib (Tarceva; OSI-774), monoclonal antibodies to EGFR (cetuximab/IMC-C225/Erbitux), and HER-2 (trastuzumab/Herceptin) are being utilized as anti-cancer therapeutics.ERRP, a recently isolated pan-EGFR inhibitor, is a 53-55-kDa protein that possesses substantial homology to the extracellular ligand-binding domain of EGFR and its family members (13). ERRP is a secretory protein that forms an inactive heterodimer with EGFR, causing inhibition of EGFR-dependent signaling events (14). ERRP inhibits proliferation and induces apoptosis as well as attenuates ligand-induced activation of EGFR and HER-2 in cancer cells th...

Development and progression of many malignancies, including colorectal cancer, are associated with activation of multiple signaling pathways. Therefore, inhibition of these signaling pathways with noncytotoxic natural products represents a logical preventive and/or therapeutic approach for colon cancer. Curcumin and resveratrol, both of which inhibit the growth of transformed cells and colon carcinogenesis, were selected to examine whether combining them would be an effective preventive and/or therapeutic strategy for colon cancer. Indeed, the combination of curcumin and resveratrol was found to be more effective in inhibiting growth of p53-positive (wt) and p53-negative colon cancer HCT-116 cells in vitro and in vivo in SCID xenografts of colon cancer HCT-116 (wt) cells than either agent alone. Analysis by Calcusyn software showed synergism between curcumin and resveratrol. The inhibition of tumors in response to curcumin and/or resveratrol was associated with the reduction in proliferation and stimulation of apoptosis accompanied by attenuation of NF-kappaB activity. In vitro studies have further demonstrated that the combinatorial treatment caused a greater inhibition of constitutive activation of EGFR and its family members as well as IGF-1R. Our current data suggest that the combination of curcumin and resveratrol could be an effective preventive/therapeutic strategy for colon cancer.

CARP-1/CCAR1, a perinuclear phosphoprotein, is a regulator of cell growth and apoptosis signaling. Although CARP-1 is a regulator of chemotherapy-dependent apoptosis, it is also a part of the NF-κB proteome and a co-activator of steroid/thyroid nuclear receptors as well as β-catenin signaling. Our yeast two-hybrid screen revealed CARP-1 binding with the anaphase-promoting complex/cyclosome E3 ubiquitin ligase component APC-2 protein. CARP-1 also binds with anaphase-promoting complex/cyclosome co-activators Cdc20 and Cdh1. Following mapping of the minimal epitopes involved in CARP-1 binding with APC-2, a fluorescence polarization assay was established that indicated a dissociation constant (K(d)) of 480 nm for CARP-1/APC-2 binding. Fluorescence polarization assay-based high throughput screening of a chemical library yielded several small molecule antagonists of CARP-1/APC-2 binding, termed CARP-1 functional mimetics. CFM-4 (1(2-chlorobenzyl)-5'-phenyl-3'H-spiro[indoline-3,2'-[1,3,4]thiadiazol]-2-one), a lead compound, binds with and stimulates CARP-1 expression. CFM-4 prevents CARP-1 binding with APC-2, causes G(2)M cell cycle arrest, and induces apoptosis with an IC(50) range of 10-15 μm. Apoptosis signaling by CFM-4 involves activation of caspase-8 and -9 and caspase-mediated ubiquitin-proteasome pathway-independent loss of cyclin B1 and Cdc20 proteins. Depletion of CARP-1, however, interferes with CFM-4-dependent cell growth inhibition, activation of caspases, and apoptosis. Because CFM-4 also suppresses growth of drug-resistant human breast cancer cells without affecting the growth of human breast epithelial MCF-10A cells, elevating CARP-1 by CFM-4 and consequent apoptosis could in principle be exploited to further elucidate, and perhaps effectively target, often deregulated cell cycle pathways in pathological conditions, including cancer.