DNA methylation and environmental exposures in human hepatocellular carcinoma

BACKGROUND: Hypermethylation of a CpG-rich promoter (CpG island) blocks expression of the corresponding gene. The CpG island methylator phenotype (CIMP), defined as a variable pattern of hypermethylation of CpG islands in tumor suppressor genes, may be associated with carcinogenesis. To determine whether CIMP is associated with the development of hepatocellular carcinoma (HCC) and with exposure to environmental agents, we examined the methylation status of CpG islands in HCCs from countries with various HCC risks. METHODS: We examined the methylation status of 12 CpG islands (eight for known genes) in 85 HCC tumors from various geographic locations by use of bisulfite-polymerase chain reaction methylation assays and analyzed results with univariate and multivariable methods. All statistical tests were two-sided. RESULTS: Eight CpG islands were hypermethylated. The frequency of hypermethylation in the 85 tumors was 62% for the estrogen receptor (ER), 42% for p16, 18% for cyclooxygenase-2, 21% for the T-type calcium channel gene, 38% for MINT31, 28% for MINT1, 15% for MINT27, and 11% for MINT2 (the latter four CpG islands are not yet associated with genes). Methylation levels of the eight frequently methylated CpG islands were positively correlated (from R =.2 [P =.05] to R =.6 [P<.001]), supporting the presence of CIMP. p16 methylation had statistically significant geographic variation (34.4% in tumors from China and Egypt versus 12.2% in tumors from the United States and Europe, difference = 22.2%; 95% confidence interval [CI] = 11.2% to 33.2%; P<.001). Similar geographic variations were observed for ER methylation and CIMP. This observation was partly related to higher methylation in tumors from patients with cirrhosis (33.6% for patients with cirrhosis versus 11.7% for those without it; difference = 21.9%; 95% CI = 10.9% to 32.8%; P<.001) or hepatitis (34.2% for patients with hepatitis versus 6.2% for those without it; difference = 28%; 95% CI = 18.3% to 37.6%; P<.001). CONCLUSION: Geographic variations in the methylation status of various CpG islands indicate that environmental factors may influence the frequent and concordant degree of hypermethylation in multiple genes in HCC tumors.     

The retinoid X receptor-selective retinoid,LGD1069, prevents the development of estrogen receptor-negative mammary tumors in transgenic mice

Despite the effectiveness of the selective estrogen receptor (ER) modulators in preventing ER-positive breast cancer, chemopreventive agents still need to be developed for the prevention of ER-negative breast cancers. The naturally occurring retinoids are promising agents for the prevention of human cancers but are too toxic for long-term chronic use. We previously demonstrated that the chemopreventive effects of the retinoids could be separated from the toxicity by using an RXR-selective retinoid, LGD1069. The studies described here demonstrate that LGD1069 effectively suppresses ER-negative tumor development in mouse mammary tumor virus-erbB2 transgenic mice with minimal toxicity. These studies suggest that receptor-selective retinoids are promising agents for the prevention of breast cancer and that they may be particularly useful in preventing ER-negative breast cancer.     

Differential sensitivity to imatinib of 2 patients with metastatic sarcoma arising from dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is a rare superficial sarcoma usually affecting the trunk, with significant risk of local recurrence. It is characterized by the presence of ring chromosomes or chromosomal translocations fusing the promoter of the collagen gene COL1A1 to the platelet-derived growth factor beta-chain gene PDGFB, increasing the production of PDGF locally and promoting autocrine or paracrine tumor growth. Fewer than 5% of patients with DFSP develop metastatic sarcoma, with a poor subsequent prognosis. Imatinib (STI-571) was developed as an inhibitor of the PDGF receptor tyrosine kinase and has proven clinical activity against chronic myelogenous leukemia (expressing bcr-abl) and gastrointestinal stromal tumors (expressing c-kit). We describe 2 patients with metastatic and unresectable metastases from DFSP treated with imatinib. After confirmation of negative CD117 status of 2 sarcomas arising from DFSP, patients were given imatinib 400 mg po qd and assessed at regular intervals for their tolerance and response to therapy. One patient had a transient response, then progressed rapidly and died of disease. Another patient showed a partial response to therapy after 2 months, with resolution of superior vena cava syndrome and shrinking of metastatic lung lesions. His response is ongoing after 6 months of therapy. These clinical data confirm findings from models of DFSP and support the use of imatinib in the rare setting of metastatic DFSP. Imatinib may be useful for patients with locally advanced DFSP, when other options for local therapy are limited.     

Autopsy findings in a human immunodeficiency virus-infected population over 2 decades: influences of gender, ethnicity, risk factors, and time

OBJECTIVES: To examine autopsy pathology in an urban population infected with the human immunodeficiency virus (HIV) and to determine if age at death and disease frequencies are associated with gender, HIV risk factors, ethnicity, and therapeutic era. DESIGN AND METHODS: Retrospective analysis of autopsy data from 394 HIV-infected adults. The population was divided into 3 therapeutic eras for analysis: group A, 1979-1986; group B, 1987-1995; and group C, 1996-2000. RESULTS: Women died at significantly younger ages than men (mean +/- SEM age, 38.9 +/- 1.0 years vs 42.5 +/- 0.64 years), even after adjustment for risk factors, ethnicity, and therapeutic era. This age discrepancy occurred despite a lower prevalence of arteriosclerosis, cachexia, and hepatitis B in women and no significant differences in the frequencies of other infectious diseases. Whites had a longer survival than patients of other ethnicities (mean age at death, 44.7 +/- 1.2 years for whites, 39.9 +/- 0.80 years for blacks, and 41.3 +/- 0.87 years for Hispanic individuals). Renal, cardiac, and splenic pathologies, Mycobacterium avium-intracellulare (MAI) infection, and cachexia were more common in blacks than in whites and/or Hispanic individuals, and cytomegalovirus and systemic lymphoma were more common in whites and Hispanic individuals than in blacks. Diseases associated with intravenous drug use were hepatitis C, cirrhosis, and tuberculosis; those with all sexual risk factors, cytomegalovirus infection, herpes simplex virus infection, and Pneumocystis carinii pneumonia; and those with homosexual risk, Kaposi sarcoma and MAI infection. The prevalence of many disease entities changed over time: compared with the other groups, group C had lower prevalences of many viral and fungal illnesses, MAI infection, systemic lymphoma, cachexia, and Kaposi sarcoma and higher prevalences of hepatitis, cirrhosis, arteriosclerosis, staphylococcal and streptococcal infections, and traumatic lesions. When the data were adjusted for changing demographic and risk composition, the only significant changes in disease frequency for period C were decreased prevalences of PCP and Kaposi sarcoma and increased prevalences of cirrhosis and arteriosclerosis. CONCLUSIONS: Significant gender- and ethnicity-related differences in age of death occurred in this HIV-infected population, and these differences were not explained by the frequencies of diseases. The lower prevalences of PCP and Kaposi sarcoma in group C are likely a reflection of the impact of potent therapies on causes of mortality. The higher prevalences of cirrhosis and arteriosclerosis suggest that entities not targeted by antiretroviral reconstitution of immunity will play an increasingly important role in HIV-related mortality in the future.     

A randomized controlled trial on the efficacy of alternative treatment regimens for uncomplicated falciparum malaria in a multidrug-resistant falciparum area of Bangladesh--narrowing the options for the National Malaria Control Programme?

We performed an open, randomized chemotherapy trial comparing the recommended first-, second- and third-line drug regimens, as well as mefloquine, for uncomplicated falciparum malaria in Bangladesh in 1996-97. The regimens were chloroquine for 3 days (CQ, Group I), quinine sulphate for 3 days followed by single-dose sulfadoxine-pyrimethamine (Q3 + SP, Group II), quinine for 7 days (Q7, Group III), and mefloquine 20 mg/kg single dose (MEF, Group IV). Subjects were symptomatic patients, aged > or = 12 years, with parasite density 500-250,000/mm3 and no history of taking antimalarials during the previous week. Drug administration was supervised and subjects were followed clinically and with blood slides in the hospital for 8 days, then as outpatients on days 14, 21 and 28. A total of 413 subjects (149, 145, 49 and 70 in Groups I-IV, respectively) completed the study. Early treatment failures (persistent or worsening clinical manifestations by day 3 confirmed with parasitological examinations) occurred only in the chloroquine group. RII and RIII parasitological failures occurred in 56%, 12%, 8% and 14% in Group I-IV, respectively. There were significantly more clinical and parasitological failures with chloroquine than with Q3 + SP, which we now recommend as a better (but far from ideal) choice for first-line therapy. The alternative compounds show parasitogical evidence of Plasmodium falciparum resistance. Further studies are needed to determine the optimum treatment for malaria in Bangladesh.     

Aerosol particle and organic vapor concentrations at industrial work sites in Malaysia

The objective of this study was to establish baseline data about air pollutants potentially related to nasopharyngeal carcinoma (NPC) in the Federal Territory and Selangor, Malaysia. During 1991-1993, ambient air quality was monitored at 42 work sites representing ten industrial sectors: adhesive manufacturing, foundries, latex processing, metalworking, plywood/veneer milling, ricemilling, rubber tire manufacturing, sawmilling, shoemaking, and textile related industries. At each work site, aerosol particle size distributions and concentrations of formaldehyde, benzene, toluene, isopropyl alcohol, and furfural were measured. Mean aerosol particle concentrations ranged from 61 micrograms/m3 in foundries to 5,578 micrograms/m3 in ricemills, with five industries (adhesives, metalworking, ricemilling, sawmilling, and shoemaking) exceeding the US EPA 24-hr ambient air standard for PM-10. Formaldehyde concentrations exceeded the threshold limit value (TLV) in adhesives factories. Other vapours and elements measured were well below TLVs.     

Bladder tumor detection at virtual cystoscopy

PURPOSE: To investigate the utility of computed tomographic (CT) virtual cystoscopy in the detection of bladder tumors. MATERIALS AND METHODS: Twenty-six patients suspected or known to have bladder neoplasms underwent CT virtual and conventional cystoscopy. The bladder was insufflated with carbon dioxide through a Foley catheter. Helical CT of the bladder was then performed. The data were downloaded to a workstation for interactive intraluminal navigation. Two radiologists blinded to the results of conventional cystoscopy independently reviewed the transverse and virtual images, with consensus readings for cases with discrepant results. RESULTS: Thirty-six (90%) of 40 bladder lesions proved at conventional cystoscopy were detected with a combination of transverse and virtual images. Four (10%) of 40 bladder lesions, all smaller than 5 mm, were undetected. Transverse and virtual images were complementary, since six polypoid lesions smaller than 5 mm depicted on the virtual images were not seen on the transverse images. In contrast, areas of wall thickening were more readily appreciated on transverse images. CT with patients in both supine and prone positions was necessary, since seven (19%) and five (14%) of 36 lesions were seen only on supine and prone images, respectively. CONCLUSION: CT virtual cystoscopy is a promising technique for use in bladder tumor detection of lesions larger than 5 mm. Optimal evaluation requires adequate bladder distention with the patient in both supine and prone positions and interpretation of both transverse and virtual images.     

Isolation and structure elucidation of viscoazucine, a novel sesquiterpene from Polygonum viscosum

A new sesquiterpene, 1,4-dimethoxycarbonyl-7-(1-methylethyl)- 3,3a,6,7,8,8a-hexahydroazulene (viscoazucine) (1), and a known flavone, 3',5,7-trihydoxy-3,4',5'-trimethoxyflavone (4), have been isolated from Polygonum viscosum. The structures of these compounds were elucidated by spectroscopic analyses, notably UV, MS and NMR.     

Lunamarin C,a new terpenoid coumarin from Clausena heptaphylla

The petroleum ether extract of the leaves of Clausena heptaphylla afforded a new coumarin, lunamarin C (1). Its structure was determined by extensive analysis of spectral data, including 2D NMR and by comparison with structurally related compounds, lunamarins A (2) and B (3).     

Instabilotyping: comprehensive identification of frameshift mutations caused by coding region microsatellite instability

Coding region frameshift mutation caused by microsatellite instability (MSI) is one mechanism contributing to tumorigenesis in cancers with MSI in high frequency. Mutation of TGFBR2 is one example of this process. To identify additional examples, a large-scale genomic screen of coding region microsatellites was conducted. 1115 coding homopolymeric loci with six or more nucleotides were identified in an online genetic database. Mutational screening was performed at 152 of these loci in 46 colorectal tumors with MSI in high frequency. Nine loci were mutated in > or =20% of tumors, 10 loci in 10-20%, 24 loci in 5-10%, 43 loci in <5%, and 66 loci were not mutated in any tumors. The most frequently mutated novel loci were the activin type II receptor gene (58.1%), SEC63 (48.8%), AIM 2 (47.6%), a gene encoding a subunit of the NADH-ubiquinone oxidoreductase complex (27.9%), a homologue of mouse cordon-bleu (23.8%), and EBP1/PA2G4 (20.9%). This genome-wide approach identifies coding region MSI in genes or pathways not implicated previously in colorectal tumorigenesis, which may merit functional study or other additional analysis.