Biomedical subjects

Susan McCarthy

Publications and source records attributed to Susan McCarthy.

11 recordsLinked to original sources

PubMed2005

Prediction of radiation sensitivity using a gene expression classifier.

The development of a successful radiation sensitivity predictive assay has been a major goal of radiation biology for several decades. We have developed a radiation classifier that predicts the inherent radiosensitivity of tumor cell lines as measured by survival fraction at 2 Gy (SF2), based on gene expression profiles obtained from the literature. Our classifier correctly predicts the SF2 value in 22 of 35 cell lines from the National Cancer Institute panel of 60, a result significantly different from chance (P = 0.0002). In our approach, we treat radiation sensitivity as a continuous variable, significance analysis of microarrays is used for gene selection, and a multivariate linear regression model is used for radiosensitivity prediction. The gene selection step identified three novel genes (RbAp48, RGS19, and R5PIA) of which expression values are correlated with radiation sensitivity. Gene expression was confirmed by quantitative real-time PCR. To biologically validate our classifier, we transfected RbAp48 into three cancer cell lines (HS-578T, MALME-3M, and MDA-MB-231). RbAp48 overexpression induced radiosensitization (1.5- to 2-fold) when compared with mock-transfected cell lines. Furthermore, we show that HS-578T-RbAp48 overexpressors have a higher proportion of cells in G2-M (27% versus 5%), the radiosensitive phase of the cell cycle. Finally, RbAp48 overexpression is correlated with dephosphorylation of Akt, suggesting that RbAp48 may be exerting its effect by antagonizing the Ras pathway. The implications of our findings are significant. We establish that radiation sensitivity can be predicted based on gene expression profiles and we introduce a genomic approach to the identification of novel molecular markers of radiation sensitivity.

Carrier Proteins↗

PubMed2005

A GM-CSF/CD40L producing cell augments anti-tumor T cell responses.

BACKGROUND: Tumors evade T cell-mediated rejection despite the presence of tumor associated antigens (TAAs) and T cells specific for these TAAs in cancer patients. Therapeutic tumor vaccines are being developed to prevent this evasion. Previous reports revealed that anti-tumor T cell responses could be activated in mice when granulocyte macrophage-colony stimulating factor (GM-CSF) or CD40L are produced at tumor vaccine sites. We sought to test the hypothesis that production of GM-CSF and CD40L by a bystander cell line could induce an anti-tumor T cell response in an in vitro human model. MATERIALS AND METHODS: The K562 cell line was stably transfected with the human GM-CSF and CD40L genes. The effect of this cell line on T cell responses was tested in a human autologous mixed tumor cell/lymph node cell model using tissue from a series of cancer patients. RESULTS: There was no significant anti-tumor T cell response when human lymphocytes derived from tumor-draining lymph nodes were stimulated with autologous tumor cells in vitro. However, significant anti-tumor T cell responses were observed when bystander cells transfected with CD40L and GM-CSF were added to the cultures. CONCLUSIONS: A fully autologous human model consisting of tumor cells as stimulator cells and tumor-draining lymph nodes as responder cells can be used to test immunotherapeutic strategies. T cells in these lymph nodes are unresponsive to autologous tumor cells, but this lack of responsiveness can be reversed in the presence of GM-CSF and CD40L. These data provide a rationale for testing tumor cell vaccines incorporating GM-CSF- and CD40L-expressing bystanders in clinical trials.

Bystander Effect↗

PubMed2005

Osteopontin induces multiple changes in gene expression that reflect the six "hallmarks of cancer" in a model of breast cancer progression.

Tumor progression is a multistep process, which enables cells to evolve from benign to malignant tumors. This progression has been suggested to depend on six essential characteristics identified as the "hallmarks of cancer," which include: self-sufficiency in growth signals, insensitivity to growth-inhibitory signals, evasion of apoptosis, limitless replicative potential, sustained angiogenesis, and tissue invasion and metastasis. Osteopontin (OPN) is an integrin-binding protein that has been shown to be associated with the progression of several cancer types, and to play an important functional role in various aspects of malignancy, particularly tissue invasion and metastasis. Here we studied genes regulated by OPN in a model of human breast cancer using oligonucleotide microarray technology by comparing the gene-expression profiles of 21NT mammary carcinoma cells transfected to overexpress OPN versus mock-transfected control cells. From over 12,000 human genes, we identified 99 known human genes differentially regulated by OPN whose expression changed by at least 1.5-fold and showed statistically significant differences in mean expression levels between groups. Functional classification of these genes into the hallmarks of cancer categories showed that OPN can affect the expression of genes involved in all six categories in this model. Furthermore, we were able to validate the expression of 18/19 selected candidate genes by quantitative real-time PCR, further supporting our microarray findings. This study provides the first evidence that OPN can lead to numerous gene expression changes that influence multiple aspects of tumor progression and malignant growth.

Breast Neoplasms↗

PubMed2004

Oncogene regulation of tumor suppressor genes in tumorigenesis.

We attempted to demonstrate whether there is an epigenetic link between oncogenes and tumor suppression genes in tumorigenesis. We designed a high throughput model to identify a candidate group of tumor suppressor genes potentially regulated by oncogenes. Gene expression profiling of mock-transfected versus v-src-transfected 3Y1 rat fibroblasts identified significant overexpression of DNA methyltransferase 1, the enzyme responsible for aberrant genome methylation, in v-src-transfected fibroblasts. Secondary microarray analyses identified a number of candidate tumor suppressor genes that were down-regulated by v-src but were also re-expressed following treatment with 5-aza-2'-deoxycytidine, a potent demethylating agent. This candidate group included both tumor suppressor genes that are known to be silenced by DNA hypermethylation and those that have not been previously identified with promoter hypermethylation. To further validate our model, we identified tsg, a tumor suppressor gene that was shown to be down-regulated by v-src and found to harbor dense promoter hypermethylation. Our model demonstrates a cooperative relationship between oncogenes and tumor suppressor genes mediated through promoter hypermethylation.

Animals↗

PubMed2004

Clusterin-mediated apoptosis is regulated by adenomatous polyposis coli and is p21 dependent but p53 independent.

Clusterin is a widely expressed glycoprotein that has been paradoxically observed to have both pro- and antiapoptotic functions. Recent reports suggest this apparent dichotomy of function may be related to two different isoforms, one secreted and cytoplasmic, the other nuclear. To clarify the functional role of clusterin in regulating apoptosis, we examined its expression in human colon cancer tissues and in human colon cancer cell lines. We additionally explored its expression and activity using models of adenomatous polyposis coli (APC)- and chemotherapy-induced apoptosis. Clusterin RNA and protein levels were decreased in colon cancer tissues largely devoid of wild-type APC when compared with matched normal tissue controls, suggesting a means for invasive cancers to avoid apoptosis. Conversely, induction of apoptosis by expression of wild-type APC or by treatment with chemotherapy led to increased clusterin RNA and protein levels localizing to apoptotic nuclei. We found that transient transfection of clusterin to colon cancer cell lines directly enhanced basal and chemotherapy-induced apoptosis. Clusterin-induced apoptosis was inhibited by antisense clusterin and was found to be highly dependent on p21 but not p53 expression, yet a deficit in p21 can be subverted by clusterin transfection. Collectively, these data support the hypothesis that nuclear clusterin function is proapoptotic when induced by APC or chemotherapy in the context of p21 expression. Absent of p21, clusterin in not induced, and apoptosis is significantly inhibited. These data support a potential therapeutic role for clusterin in enhancing chemotherapy-induced apoptosis and in promoting apoptosis in cells deficient in p21.

Adenomatous Polyposis Coli Protein↗

PubMed2004

VERB - a social marketing campaign to increase physical activity among youth.

The VERB campaign is a multiethnic media campaign with a goal to increase and maintain physical activity among tweens, or children aged nine to 13 years. Parents, especially mothers aged 29 to 46, and other sources of influence on tweens (e.g., teachers, youth program leaders) are the secondary audiences of the VERB initiative. VERB applies sophisticated commercial marketing techniques to address the public health problem of sedentary lifestyles of American children, using the social marketing principles of product, price, place, and promotion. In this paper, we describe how these four principles were applied to formulate the strategies and tactics of the VERB campaign, and we provide examples of the multimedia materials (e.g., posters, print advertising, television, radio spots) that were created.

Adolescent↗

PubMed2004

Susceptibility to allergic lung disease regulated by recall responses of dual-receptor memory T cells.

BACKGROUND: Microbial infections are associated with the initial susceptibility to and flares of asthma. However, immunologic mechanisms whereby infections might alter the asthmatic phenotype are lacking. OBJECTIVE: To test the hypothesis that memory T cells specific both for a viral antigen and an allergen could influence the pathogenesis of allergic disease in vivo . METHODS: We developed a system in which 2 distinct T-cell receptors coexist on the T-cell surface, 1 specific for a virus and the other for an inhaled antigen. RESULTS: We show that a population of dual-receptor T cells, polarized through a virus-specific T-cell receptor to contain T(H)1 or T(H)2 cells, can be reactivated through an unrelated T-cell receptor in recall responses in vivo . Quiescent memory cells derived from a T(H)1-polarized effector population blocked the development of airway hyperreactivity in a model of allergic lung disease, in association with decreased induction of chemokines and eosinophil recruitment. Conversely, reactivation of quiescent T(H)2 cells after inhalation of antigen or virus infection was sufficient to lead to the development of airway hyperresponsiveness and allergic pulmonary inflammation in mice whose lungs were previously normal. CONCLUSION: These data provide evidence that dual-receptor memory T cells can regulate allergic disease susceptibility and suggest that they may play a role in mediating the influence of microbes on asthma pathogenesis.

Animals↗

PubMed2004

Medical students' exposure to pharmaceutical industry marketing: a survey at one U.S. medical school.

PURPOSE: While much is known about the interactions between the pharmaceutical industry and physicians, very little is known about pharmaceutical marketing directed toward medical students. This study sought to characterize the extent and forms of medical students' exposure to pharmaceutical industry marketing. METHOD: In 2001-02, an anonymous, 17-item questionnaire was distributed to 165 preclinical and 116 clinical students at the University of Minnesota Medical School-Twin Cities. The main outcome measures were the number and forms of exposures to pharmaceutical industry marketing reported by medical students and whether students had discussed these exposures with teachers or advisors. Preclinical and clinical students were compared using chi(2) analysis (p < .05). RESULTS: One hundred fourteen (69.1%) preclinical students and 107 (92.2%) clinical students responded. Nearly all students reported at least one exposure to pharmaceutical industry marketing. Seventy-six (71.7%) clinical students compared to 38 (33.3%) preclinical students recalled over 20 exposures (p < .005). Clinical students were more likely to have received a free meal (p < .01), textbook (p < .005), pocket text (p < .005), or trinket (p < .005) than were their preclinical colleagues. Most students (68.2%) had not discussed pharmaceutical marketing with an instructor or advisor; 59 (55.7%) clinical students as compared to 87 (80.6%) preclinical students recalled no such discussion (p < .005). CONCLUSION: Medical students have extensive exposure to pharmaceutical industry marketing during their early years of training. Given existing evidence that such exposure influences physicians' practice and prescribing patterns, the authors propose that medical school curricula include formal instruction to prepare students to critically assess these contacts.

Adult↗

PubMed2003

Recall helper T cell response: T helper 1 cell-resistant allergic susceptibility without biasing uncommitted CD4 T cells.

Effector and memory T lymphocytes differ significantly, and there is no experimental evidence that memory cells are sufficient to render an otherwise normal individual susceptible to localized allergic inflammation. Furthermore, nothing is known about the kinetics of memory responses after inhalation of antigen or interplay between an allergen-specific memory helper T (Th) cell Th2 population and uncommitted or competing Th1 cells. To study these processes, T cell receptor-transgenic CD4(+) effector cells were generated in vitro, transferred into naive recipients, and allowed to resume a quiescent state. Inhalation of protein antigen reactivated these Ag-specific Th2 donor cells, leading to allergic pulmonary inflammation and airway hyperreactivity. Susceptibility was correlated with the size of the input Th2 population, but Th1 cells neither enhanced nor reduced inflammation in this model. Importantly, the reactivation of these antigen-experienced cells by inhaled antigen did not skew the cytokine balance of recipient-derived T cells recruited to the lung nor did it inhibit the development of donor-derived Th1 cells from uncommitted antigen-experienced cells that form a normal part of immune responses. These data indicate that a quiescent memory Th2-cell population can create susceptibility to allergic pulmonary inflammation in a manner refractory to inhibition by Th1 cells or endogenous inhibitory mechanisms.

Animals↗

PubMed2003

T cell-intrinsic requirement for NF-kappa B induction in postdifferentiation IFN-gamma production and clonal expansion in a Th1 response.

NF-kappaB/Rel transcription factors are linked to innate immune responses and APC activation. Whether and how the induction of NF-kappaB signaling in normal CD4(+) T cells regulates effector function are not well-understood. The liberation of NF-kappaB dimers from inhibitors of kappaB (IkappaBs) constitutes a central checkpoint for physiologic regulation of most forms of NF-kappaB. To investigate the role of NF-kappaB induction in effector T cell responses, we targeted inhibition of the NF-kappaB/Rel pathway specifically to T cells. The Th1 response in vivo is dramatically weakened when T cells defective in their NF-kappaB induction (referred to as IkappaBalpha(DeltaN) transgenic cells) are activated by a normal APC population. Analyses in vivo, and IL-12-supplemented T cell cultures in vitro, reveal that the mechanism underlying this T cell-intrinsic requirement for NF-kappaB involves activation of the IFN-gamma gene in addition to clonal expansion efficiency. The role of NF-kappaB in IFN-gamma gene expression includes a modest decrease in Stat4 activation, T box expressed in T cell levels, and differentiation efficiency along with a more prominent postdifferentiation step. Further, induced expression of Bcl-3, a trans-activating IkappaB-like protein, is decreased in T cells as a consequence of NF-kappaB inhibition. Together, these findings indicate that NF-kappaB induction in T cells regulates efficient clonal expansion, Th1 differentiation, and IFN-gamma production by Th1 lymphocytes at a control point downstream from differentiation.

Adoptive Transfer↗

PubMed2002

Characterization of United States outbreak isolates of Vibrio parahaemolyticus using enterobacterial repetitive intergenic consensus (ERIC) PCR and development of a rapid PCR method for detection of O3:K6 isolates.

Outbreaks of Vibrio parahaemolyticus gastroenteritis in the United States (Texas, New York and Pacific Northwest) in 1997-98 emphasized the need to develop molecular methods for identification and differentiation of these organisms. When outbreak isolates were analyzed for the enterobacterial repetitive intergenic consensus sequences, the Texas and New York outbreak isolates had a specific 850-bp DNA fragment that was absent in Pacific Northwest isolates. The 850-bp polymerase chain reaction (PCR) product was found in isolates of serovar O3:K6, which have an unusual potential to spread and cause infections. To develop a specific molecular detection method for serovar O3:K6, the nucleotide sequence of the 850-bp product was determined. The GenBank blast analysis did not show homology with any known Vibrio spp. gene sequences. Two PCR primers were designed to specifically amplify the unique sequences from serovar O3:K6 isolates. Genomic DNA from 10 Texas, eight New York, and seven Pacific Northwest outbreak isolates of V. parahaemolyticus was assayed by PCR. Texas and New York isolates were positive in the PCR assay, giving a 327-bp PCR product as predicted; however, Pacific Northwest isolates were negative, indicating the absence of the target gene. Texas and New York isolates were all serovar O3:K6; the Pacific Northwest isolates were not. The primers were tested with other Vibrio spp. and other closely related species and no amplification of the 327-bp PCR product was found. The PCR method can be used to specifically identify O3:K6 V. parahaemolyticus isolates in less than 6 h.

Base Sequence↗