The primary aim of this study was to evaluate the antitumor efficacy of the bromodomain inhibitor JQ1 in pancreatic ductal adenocarcinoma (PDAC) patient-derived xenograft (tumorgraft) models. A ...secondary aim of the study was to evaluate whether JQ1 decreases expression of the oncogene c-Myc in PDAC tumors, as has been reported for other tumor types. We used five PDAC tumorgraft models that retain specific characteristics of tumors of origin to evaluate the antitumor efficacy of JQ1. Tumor-bearing mice were treated with JQ1 (50 mg/kg daily for 21 or 28 days). Expression analyses were performed with tumors harvested from host mice after treatment with JQ1 or vehicle control. An nCounter PanCancer Pathways Panel (NanoString Technologies) of 230 cancer-related genes was used to identify gene products affected by JQ1. Quantitative RT-PCR, immunohistochemistry and immunoblots were carried out to confirm that changes in RNA expression reflected changes in protein expression. JQ1 inhibited the growth of all five tumorgraft models (P<0.05), each of which harbors a KRAS mutation; but induced no consistent change in expression of c-Myc protein. Expression profiling identified CDC25B, a regulator of cell cycle progression, as one of the three RNA species (TIMP3, LMO2 and CDC25B) downregulated by JQ1 (P<0.05). Inhibition of tumor progression was more closely related to decreased expression of nuclear CDC25B than to changes in c-Myc expression. JQ1 and other agents that inhibit the function of proteins with bromodomains merit further investigation for treating PDAC tumors. Work is ongoing in our laboratory to identify effective drug combinations that include JQ1.
An update on androgen-deprivation therapy in prostate cancer and cardiovascular risk based on medical research brought by the American Heart Association, American Cancer Society, and American ...Urological Association, is presented.
Progressive metastatic disease is a major cause of mortality for patients diagnosed with multiple types of solid tumors. One of the long-term goals of our laboratory is to identify molecular ...interactions that regulate metastasis, as a basis for developing agents that inhibit this process. Toward this goal, we recently demonstrated that intercellular adhesion molecule-2 (ICAM-2) converted neuroblastoma (NB) cells from a metastatic to a non-metastatic phenotype, a previously unknown function for ICAM-2. Interestingly, ICAM-2 suppressed metastatic but not tumorigenic potential in preclinical models, supporting a novel mechanism of regulating metastasis. We hypothesized that the effects of ICAM-2 on NB cell phenotype depend on the interaction of ICAM-2 with the cytoskeletal linker protein α-actinin. The goal of the study presented here was to evaluate the impact of α-actinin binding to ICAM-2 on the phenotype of NB tumor cells. We used in silico approaches to examine the likelihood that the cytoplasmic domain of ICAM-2 binds directly to α-actinin. We then expressed variants of ICAM-2 with mutated α-actinin-binding domains, and compared the impact of ICAM-2 and each variant on NB cell adhesion, migration, anchorage-independent growth, co-precipitation with α-actinin and production of localized and disseminated tumors in vivo. The in vitro and in vivo characteristics of cells expressing ICAM-2 variants with modified α-actinin-binding domains differed from cells expressing ICAM-2 wild type (WT) and also from cells that expressed no detectable ICAM-2. Like the WT protein, ICAM-2 variants inhibited cell adhesion, migration and colony growth in vitro. However, unlike the WT protein, ICAM-2 variants did not completely suppress development of disseminated NB tumors in vivo. The data suggest the presence of α-actinin-dependent and α-actinin-independent mechanisms, and indicate that the interaction of ICAM-2 with α-actinin is critical to conferring an ICAM-2-mediated non-metastatic phenotype in NB cells.
The study of low dose and low-dose rate exposure is of central importance in understanding the possible range of health effects from prolonged exposures to radiation. The One Million Person Study of ...Radiation Workers and Veterans (MPS) of low-dose health effects was designed to evaluate radiation risks among healthy American workers and veterans. The MPS is evaluating low-dose and dose-rate effects, intakes of radioactive elements, cancer and non-cancer outcomes, as well as differences in risks between women and men. Medical radiation workers make up a large group of individuals occupationally exposed to low doses of radiation from external x-ray/gamma exposures. For the MPS, about 100 000 United States medical radiation workers have been selected for study. The approach to the complex dosimetry circumstances for such workers over three to four decades of occupation were initially and broadly described in National Council on Radiation Protection and Measurements (NCRP) Report No. 178. NCRP Commentary No. 30 provides more detail and describes an optimum approach for using personal monitoring data to estimate lung and other organ doses applicable to the cohort and provides specific precautions/considerations applicable to the dosimetry of medical radiation worker organ doses for use in epidemiologic studies. The use of protective aprons creates dosimetric complexity. It is recommended that dose values from dosimeters worn over a protective apron be reduced by a factor of 20 for estimating mean organ doses to tissues located in the torso and that 15% of the marrow should be assumed to remain unshielded for exposure scenarios when aprons are worn. Conversion coefficients relating personal dose equivalent,
(10) in mSv, to mean absorbed doses to organs and tissues,
in mGy, for females and males for six exposure scenarios have been determined and presented for use in the MPS. This Memorandum summarises several key points in NCRP Commentary No. 30.
CD44 is a transmembrane glycoprotein involved in numerous cellular functions, including cell adhesion and extracellular matrix interactions. It is known to be functionally diverse, with alternative ...splice variants increasingly implicated as a marker for tumor-initiating stem cells associated with poor prognosis. Here, we evaluate CD44 as a potential marker of long-term breast cancer outcomes. Tissue specimens from patients treated on the National Cancer Institute 79-C-0111 randomized trial of breast conservation versus mastectomy between 1979 and 1987 were collected, and immunohistochemistry was performed using the standard isoform of CD44. Specimens were correlated with patient characteristics and outcomes. Survival analysis was performed using the log rank test. Fifty-one patients had evaluable tumor sections and available long-term clinical follow up data at a median follow up of 25.7 years. Significant predictors of OS were tumor size (median OFS 25.4 years for ≤2 cm vs. 7.5 years for >2 cm,
p
= 0.001), nodal status (median OS 17.2 years for node-negative patients vs. 6.7 years for node positive patients,
p
= 0.017), and CD44 expression (median OS 18.9 years for CD44 positive patients vs. 8.6 years for CD44 negative patients,
p
= 0.049). There was a trend toward increased PFS for patients with CD44 positive tumors (median PFS 17.9 vs. 4.3 years,
p
= 0.17), but this did not reach statistical significance. These findings illustrate the potential utility of CD44 as a prognostic marker for early stage breast cancer. Subgroup analysis in patients with lymph node involvement revealed CD44 positivity to be most strongly associated with increased survival, suggesting a potential role of CD44 in decision making for axillary management. As there is increasing interest in CD44 as a therapeutic target in ongoing clinical trials, the results of this study suggest additional investigation regarding the role CD44 in breast cancer is warranted.
Reducing the addictiveness of cigarettes Henningfield, Jack E; Benowitz, Neal L; Slade, John ...
Tobacco Control,
09/1998, Letnik:
7, Številka:
3
Journal Article, Book Review
Recenzirano
Odprti dostop
OBJECTIVE To assess the feasibility of reducing tobacco-caused disease by gradually removing nicotine from cigarettes until they would not be effective causes of nicotine addiction. DATA SOURCES ...Issues posed by such an approach, and potential solutions, were identified from analysis of literature published by the US Food and Drug Administration (FDA) in its 1996 Tobacco Rule, comments of the tobacco industry and other institutions and individuals on the rule, review of the reference lists of relevant journal articles, other government publications, and presentations made at scientific conferences. DATA SYNTHESIS The role of nicotine in causing and sustaining tobacco use was evaluated to project the impact of a nicotine reduction strategy on initiation and maintenance of, and relapse to, tobacco use. A range of potential concerns and barriers was addressed, including the technical feasibility of reducing cigarette nicotine content to non-addictive levels, the possibility that compensatory smoking would reduce potential health benefits, and whether such an approach would foster illicit (“black market”) tobacco sales. Education, treatment, and research needs to enable a nicotine reduction strategy were also addressed. The Council on Scientific Affairs came to the following conclusions: (a) gradually eliminating nicotine from cigarettes is technically feasible; (b) a nicotine reduction strategy holds great promise in preventing adolescent tobacco addiction and assisting the millions of current cigarette smokers in their efforts to quit using tobacco products; (c) potential problems such as compensatory over-smoking of denicotinised cigarettes and black market sales could be minimised by providing alternate forms of nicotine delivery with less or little risk to health, as part of expanded access to treatment; and (d) such a strategy would need to be accompanied by relevant research and increased efforts to educate consumers and health professionals about tobacco and health. CONCLUSIONS The council recommends the following: (a) that cessation of tobacco use should be the goal for all tobacco users; (b) that the American Medical Association continue to support FDA authority over tobacco products, and FDA classification of nicotine as a drug and tobacco products as drug-delivery devices; (c) that research be encouraged on cigarette modifications that may result in less addicting cigarettes; (d) that the FDA require that the addictiveness of cigarettes be reduced within 5–10 years; (e) expanded surveillance to monitor trends in the use of tobacco products and other nicotine-containing products; (f) expanded access to smoking cessation treatment, and strengthening of the treatment infrastructure; and (g) more accurate labelling of tobacco products, including a more meaningful and understandable indication of nicotine content.
A membrane preparation from tobacco (Nicotiana tabacum L.) cells contains at least one enzyme that is capable of transferring the methyl group from S-adenosyl-methionine (SAM) to the C6 carboxyl of ...homogalacturonan present in the membranes. This enzyme is named homogalacturonan-methyltransferase (HGA-MT) to distinguish it from methyltransferases that catalyze methyletherification of the pectic polysaccharides rhamnogalacturonan I or rhamnogalacturonan II. A trichloroacetic acid precipitation assay was used to measure HGA-MT activity, because published procedures to recover pectic polysaccharides via ethanol or chloroform:methanol precipitation lead to high and variable background radioactivity in the product pellet. Attempts to reduce the incorporation of the 14C-methyl group from SAM into pectin by the addition of the alternative methyl donor 5-methyltetrahydrofolate were unsuccessful, supporting the role of SAM as the authentic methyl donor for HGA-MT. The pH optimum for HGA-MT in membranes was 7.8, the apparent Michaelis constant for SAM was 38 μM, and the maximum initial velocity was 0.81 pkat mg-1 protein. At least 59% of the radiolabeled product was judged to be methylesterified homogalacturonan, based on the release of radioactivity from the product after a mild base treatment and via enzymatic hydrolysis by a purified pectin methylesterase. The released radioactivity eluted with a retention time identical to that of methanol upon fractionation over an organic acid column. Cleavage of the radiolabeled product by endopolygalacturonase into fragments that migrated as small oligomers of HGA during thin-layer chromatography, and the fact that HGA-MT activity in the membranes is stimulated by uridine 5′-diphosphate galacturonic acid, a substrate for HGA synthesis, confirms that the bulk of the product recovered from tobacco membranes incubated with SAM is methylesterified HGA.
Progressive metastatic disease is a major cause of mortality for patients diagnosed with multiple types of solid tumors. One of the long-term goals of our laboratory is to identify molecular ...interactions that regulate metastasis, as a basis for developing agents that inhibit this process. Toward this goal, we recently demonstrated that intercellular adhesion molecule-2 (ICAM-2) converted neuroblastoma (NB) cells from a metastatic to a non-metastatic phenotype, a previously unknown function for ICAM-2. Interestingly, ICAM-2 suppressed metastatic but not tumorigenic potential in preclinical models, supporting a novel mechanism of regulating metastasis. We hypothesized that the effects of ICAM-2 on NB cell phenotype depend on the interaction of ICAM-2 with the cytoskeletal linker protein -actinin. The goal of the study presented here was to evaluate the impact of -actinin binding to ICAM-2 on the phenotype of NB tumor cells. We used in silico approaches to examine the likelihood that the cytoplasmic domain of ICAM-2 binds directly to -actinin. We then expressed variants of ICAM-2 with mutated -actinin-binding domains, and compared the impact of ICAM-2 and each variant on NB cell adhesion, migration, anchorage-independent growth, co-precipitation with -actinin and production of localized and disseminated tumors in vivo. The in vitro and in vivo characteristics of cells expressing ICAM-2 variants with modied -actinin-binding domains differed from cells expressing ICAM-2 wild type (WT) and also from cells that expressed no detectable ICAM-2. Like the WT protein, ICAM-2 variants inhibited cell adhesion, migration and colony growth in vitro. However, unlike the WT protein, ICAM-2 variants did not completely suppress development of disseminated NB tumors in vivo
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