Citations

Abstract Celiac disease is associated with an increased risk of small bowel adenocarcinoma. The aims of this study were to investigate the molecular basis, assess outcomes, and identify clinicopathologic characteristics of small bowel adenocarcinoma in celiac disease. Retrospective case control cohort study of all celiac disease patients treated at our institution for small bowel adenocarcinoma and matched control patients with sporadic small bowel adenocarcinoma from July 1960 to November 2002. Mismatch repair (MMR) status was accessed by testing tissue for microsatellite instability (MSI) and for hMLH1 and hMSH2 protein expression. Over a 40-year time period, 18 patients with small bowel adenocarcinoma and celiac disease were treated at the Mayo Clinic. One celiac disease patient was excluded. High-frequency MSI (MSI-H) was identified in 8 of 11 (73%) and 2 of 22 (9%) available small bowel adenocarcinoma specimens in the celiac disease and control groups, respectively. In the celiac disease group, MSI-H was associated with loss of hMLH1 and hMSH2 in 6 and 1 specimens, respectively. Loss of hMLH1 occurred in both control tumors. Stage was associated with celiac disease status (P = 0.018), and 78% of controls were stage III or IV compared with 47% of celiac disease patients. Overall, survival was better (P = 0.025) in the celiac disease group compared with stage-matched controls. Celiac disease patients with small bowel adenocarcinoma had a high incidence defective MMR (73%) compared with controls and had better survival compared with stage-matched controls. In addition, celiac disease patients presented more frequently with early-stage small bowel adenocarcinoma. The better survival and earlier presentation of small bowel adenocarcinoma in celiac disease appears to be biologically associated with defective MMR.

Abstract Many important physiological and pathological processes are modulated by angiogenesis. It has been shown that initiation of this angiogenic process is an essential early step in the progression of malignant tumors. We report here that ablation of peripheral dopaminergic nerves markedly increased angiogenesis, microvessel density, microvascular permeability, and growth of malignant tumors in mice. Endogenous peripheral dopamine acted through D2 receptors as significantly more angiogenesis and tumor growth was observed in D2 dopamine receptor knockout mice in comparison with controls. The vascular endothelial growth factor receptor 2 phosphorylation, which is critical for promoting angiogenesis, was also significantly more in tumor endothelial cells collected from the dopamine-depleted and D2 dopamine receptor knockout animals. These results reveal that peripheral endogenous neurotransmitter dopamine might be an important physiological regulator of vascular endothelial growth factor-mediated tumor angiogenesis and growth and suggest a novel link between endogenous dopamine, angiogenesis, and tumor growth.

AbstractLive attenuated Edmonston B strain of measles virus (MV-Edm) is a potent and specific oncolytic agent, but the mechanism underlying its tumor selectivity is unknown. The virus causes cytopathic effects (CPEs) of extensive syncytial formation in tumor cells but minimal damage or cell killing in normal cells. The CPE is dependent on expression of viral proteins and the presence of CD46, the major cellular receptor of MV-Edm. Using a virally encoded soluble marker peptide to provide a quantitative readout of the level of viral gene expression, we determined that tumor cells and normal cells expressed comparable levels of viral proteins. CD46 mediates virus attachment, entry, and virus-induced cell-to-cell fusion. Using engineered cells expressing a range of CD46 densities, we determined that whereas virus entry increased progressively with CD46 density, cell fusion was minimal at low receptor densities but increased dramatically above a threshold density of CD46 receptors. It is well established that tumor cells express abundant CD46 receptors on their surfaces compared with their normal counterparts. Thus, at low CD46 densities typical of normal cells, infection occurs, but intercellular fusion is negligible. At higher densities typical of tumor cells, infection leads to extensive cell fusion. Intercellular fusion also results in enhancement of viral gene expression through recruitment of neighboring uninfected cells into the syncytium, further amplifying the CPE. Discrimination between high and low CD46 receptor density provides a compelling basis for the oncolytic specificity of MV-Edm and establishes MV-Edm as a promising CD46-targeted cancer therapeutic agent.

Abstract This study demonstrates that verapamil and a newly synthesized verapamil derivative, NMeOHI2, behave as apoptogens in multidrug resistance protein 1 (MRP1)-expressing cells. When treated with either verapamil or NMeOHI2, surprisingly, baby hamster kidney-21 (BHK) cells transfected with human MRP1 were killed. Because parental BHK cells were not, as well as cells expressing an inactive (K1333L) MRP1 mutant, this indicated that cell death involved functional MRP1 transporter. Cell death was identified as apoptosis by using annexin V-fluorescein labeling and was no longer observed in the presence of the caspase inhibitor Z-Val-Ala-Asp(OMe)-CH2F (Z-VAD-FMK). In vitro, both verapamil and its derivative inhibited leukotriene C4 transport by MRP1-enriched membrane vesicles in a competitive manner, with a Ki of 48.6 μm for verapamil and 5.5 μm for NMeOHI2, and stimulated reduced glutathione (GSH) transport 3-fold and 9-fold, respectively. Treatment of MRP1-expressing cells with either verapamil or the derivative quickly depleted intracellular GSH content with a strong decrease occurring in the first hour of treatment, which preceded cell death beginning at 8–16 h. Furthermore, addition of GSH to the media efficiently prevented cell death. Therefore, verapamil and its derivative trigger apoptosis through stimulation of GSH extrusion mediated by MRP1. This new information on the mechanism of induced apoptosis of MDR cells may represent a novel approach in the selective treatment of MRP1-positive tumors.

Abstract The MutLα heterodimer formed by mismatch repair (MMR) proteins MLH1 and PMS2 is a major component of the MMR complex, yet mutations in the PMS2 gene are rare in the etiology of hereditary nonpolyposis colorectal cancer. Evidence from five published cases suggested that contrary to the Knudson principle, PMS2 mutations cause hereditary nonpolyposis colorectal cancer or Turcot syndrome only when they are biallelic in the germline or abnormally expressed. As candidates for PMS2 mutations, we selected seven patients whose colon tumors stained negative for PMS2 and positive for MLH1 by immunohistochemistry. After conversion to haploidy, truncating germline mutations of PMS2 were found in two patients (2192delTAACT and deletion of exon 8). These mutations abrogated PMS2 protein in germline cells by Western analysis. In two additional patients, PMS2 protein from one allele also was abrogated. Novel or previously described missense variants of PMS2 were detected, but their pathogenicity is undetermined. We detected and characterized a new transcript, PMS2CL, showing 98% sequence identity with exons 9 and 11–15 of PMS2 and emanating from a locus close to PMS2 in chromosome 7p. Its predicted protein product was not detected. Thus, in addition to several previously described PMS2-related genes resembling the 5′ end of PMS2, at least one related gene resembles the 3′ end of PMS2. In conclusion, both detectable and presently undefined germline mutations are deleterious and produce susceptibility to cancer by the two-hit mechanism. Paralogous genes interfere with mutation detection, resulting in underdiagnosis of PMS2 mutations. Mutation detection in PMS2 requires haploid DNA.

AbstractCholangiocarcinomas are usually fatal neoplasms originating from bile duct epithelia. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising agent for cancer therapy, including cholangiocarcinoma. However, many cholangiocarcinoma cells are resistant to TRAIL-mediated apoptosis. Thus, our aim was to examine the intracellular mechanisms responsible for TRAIL resistance in human cholangiocarcinoma cell lines. Three TRAIL-resistant human cholangiocarcinoma cell lines were identified. All of the cell lines expressed TRAIL receptor 1/death receptor 4 (TRAIL-R1/DR4) and TRAIL-R2/DR5. Expression of TRAIL decoy receptors and the antiapoptotic cellular FLICE-inhibitory protein (cFLIP) was inconsistent across the cell lines. Of the antiapoptotic Bcl-2 family of proteins profiled (Bcl-2, Bcl-xL, and Mcl-1), Mcl-1 was uniquely overexpressed by the cell lines. When small-interfering-RNA (siRNA) technology was used to knock down expression of Bcl-2, Bcl-xL, and Mcl-1, only the Mcl-1-siRNA sensitized the cells to TRAIL-mediated apoptosis. In a cell line stably transfected with Mcl-1-small-hairpin-RNA (Mcl-1-shRNA), Mcl-1 depletion sensitized cells to TRAIL-mediated apoptosis despite Bcl-2 expression. TRAIL-mediated apoptosis in the stably transfected cells was associated with mitochondrial depolarization, Bax activation, cytochrome c release from mitochondria, and caspase activation. Finally, flavopiridol, an anticancer drug that rapidly down-regulates Mcl-1, also sensitized cells to TRAIL cytotoxicity. In conclusion, these studies not only demonstrate that Mcl-1 mediates TRAIL resistance in cholangiocarcinoma cells by blocking the mitochondrial pathway of cell death but also identify two strategies for circumventing this resistance.

Abstract Individuals with a family history of pancreatic cancer have an increased risk of developing pancreatic cancer. Quantification of this risk provides a rational basis for cancer risk counseling and for screening for early pancreatic cancer. In a prospective registry-based study, we estimated the risk of pancreatic cancer in individuals with a family history of pancreatic cancer. Standardized incidence ratios were calculated by comparing the number of incident pancreatic cancers observed with those expected using Surveillance, Epidemiology and End Results (SEER) rates. Familial pancreatic cancer (FPC) kindreds were defined as kindreds having at least one pair of first-degree relatives with pancreatic cancer, and sporadic pancreatic cancer (SPC) kindreds as families without such an affected pair. Nineteen incident pancreatic cancers developed among 5,179 individuals from 838 kindreds (at baseline, 370 FPC kindreds and 468 SPC kindreds). Of these 5,179 individuals, 3,957 had at least one first-degree relative with pancreatic cancer and contributed 10,538 person-years of follow-up. In this group, the observed-to-expected rate of pancreatic cancer was significantly elevated in members of FPC kindreds [9.0; 95% confidence interval (CI), 4.5–16.1], but not in the SPC kindreds (1.8; 95% CI., 0.22–6.4). This risk in FPC kindreds was elevated in individuals with three (32.0; 95% CI, 10.2–74.7), two (6.4; CI, 1.8–16.4), or one (4.6; CI, 0.5–16.4) first-degree relative(s) with pancreatic cancer. Risk was not increased among 369 spouses and other genetically unrelated relatives. Risk was higher in smokers than in nonsmokers. Individuals with a strong family history of pancreatic cancer have a significantly increased risk of developing pancreatic cancer.

Abstract Aneurysmal bone cyst (ABC) is a locally aggressive osseous lesion that typically occurs during the first two decades of life. ABC was regarded historically as a nonneoplastic process, but recent cytogenetic data have shown clonal rearrangements of chromosomal bands 16q22 and 17p13, indicating a neoplastic basis in at least some ABCs. Herein we show that a recurring ABC chromosomal translocation t(16;17)(q22;p13) creates a fusion gene in which the osteoblast cadherin 11 gene (CDH11) promoter region on 16q22 is juxtaposed to the entire ubiquitin-specific protease USP6 (Tre2) coding sequence on 17p13. CDH11-USP6 fusion transcripts were demonstrated only in ABC with t(16;17) but other ABCs had CDH11 or USP6 rearrangements resulting from alternate cytogenetic mechanisms. CDH11 is expressed strongly in bone, and our findings implicate a novel oncogenic mechanism in which deregulated USP6 transcription results from juxtaposition to the highly active CDH11 promoter.

Abstract Whereas two key steps in cervical carcinogenesis are integration of high-risk human papillomavirus (HR-HPV) and acquisition of an unstable host genome, the temporal association between these events is poorly understood. Chromosomal instability is induced when HR-HPV E7 oncoprotein is overexpressed from heterologous promoters in vitro. However, it is not known whether such events occur at the “physiologically” elevated levels of E7 produced by deregulation of the homologous HR-HPV promoter after integration. Indeed, an alternative possibility is that integration in vivo is favored in an already unstable host genome. We have addressed these issues using the unique human papillomavirus (HPV) 16-containing cervical keratinocyte cell line W12, which was derived from a low-grade squamous intraepithelial lesion and thus acquired HPV16 by “natural” infection. Whereas W12 at low passage contains HPV16 episomes only, long-term culture results in the emergence of cells containing integrated HPV16 only. We show that integration of HPV16 in W12 is associated with 3′ deletion of the E2 transcriptional repressor, resulting in deregulation of the homologous promoter of the integrant and an increase in E7 protein levels. We further demonstrate that high-level chromosomal instability develops in W12 only after integration and that the forms of instability observed correlate with the physical state of HPV16 DNA and the level of E7 protein. Whereas intermediate E7 levels are associated with numerical chromosomal abnormalities, maximal levels are associated with both numerical and structural aberrations. HR-HPV integration is likely to be a critical event in cervical carcinogenesis, preceding the development of chromosomal abnormalities that drive malignant progression.

Abstract Much has been learned regarding the biology and clinical implications of genetic abnormalities in multiple myeloma. Because of recent advances in the field, an International Workshop was held in Paris in February of 2003. This summary describes the consensus recommendations arising from that meeting with special emphasis on novel genetic observations. For instance, it is increasingly clear that translocations involving the immunoglobulin heavy-chain locus are important for the pathogenesis of one-half of patients. As a corollary, it also clear that the remaining patients, lacking IgH translocations, have hyperdiploidy as the hallmark of their disease. Several important genetic markers are associated with a shortened survival such as chromosome 13 monosomy, hypodiploidy, and others. The events leading the transformation of the monoclonal gammopathy of undetermined significance (MGUS) to myeloma are still unclear. One of the few differential genetic lesions between myeloma and MGUS is the presence of ras mutations in the latter. Gene expression platforms are capable of detecting many of the genetic aberrations found in the clonal cells of myeloma. Areas in need of further study were identified. The study of the genetic aberrations will likely form the platform for targeted therapy for the disease.