Recent preclinical studies have associated beta-adrenergic receptor (beta-AR) signaling with breast cancer pathways such as progression and metastasis. These findings have been supported by clinical and epidemiologica...
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Recent preclinical studies have associated beta-adrenergic receptor (beta-AR) signaling with breast cancer pathways such as progression and metastasis. These findings have been supported by clinical and epidemiological studies which examined the effect of beta-blocker therapy on breast cancer metastasis, recurrence and mortality. Results from these studies have provided initial evidence for the inhibition of cell migration in breast cancer by beta-blockers and have introduced the beta-adrenergic receptor pathways as a target for therapy. This paper analyzes gene expression profiles in breast cancer patients, utilising Artificial Neural Networks (ANNs) to identify molecular signatures corresponding to possible disease management pathways and biomarker treatment strategies associated with beta-2-adrenergic receptor (ADRB2) cell signaling. The adrenergic receptor relationship to cancer is investigated in order to validate the results of recent studies that suggest the use of beta-blockers for breast cancer therapy. A panel of genes is identified which has previously been reported to play an important role in cancer and also to be involved in the beta-adrenergic receptor signaling.
Background: Multivariate ordination methods are powerful tools for the exploration of complex data structures present in microarray data. These methods have several advantages compared to common gene-by-gene approache...
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Background: Multivariate ordination methods are powerful tools for the exploration of complex data structures present in microarray data. These methods have several advantages compared to common gene-by-gene approaches. However, due to their exploratory nature, multivariate ordination methods do not allow direct statistical testing of the stability of genes. Results: In this study, we developed a computationally efficient algorithm for: i) the assessment of the significance of gene contributions and ii) the identification of sample outliers in multivariate analysis of microarray data. The approach is based on the use of resampling methods including bootstrapping and jackknifing. A statistical package of R functions was developed. This package includes tools for both inferring the statistical significance of gene contributions and identifying outliers among samples. Conclusion: The methodology was successfully applied to three published data sets with varying levels of signal intensities. Its relevance was compared with alternative methods. Overall, it proved to be particularly effective for the evaluation of the stability of microarray data.
This paper presents a simple and novel curve fitting approach for generating simple gene regulatory subnetworks from time series gene expression data. microarray experiments simultaneously generate massive data sets a...
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This paper presents a simple and novel curve fitting approach for generating simple gene regulatory subnetworks from time series gene expression data. microarray experiments simultaneously generate massive data sets and help immensely in the large-scale study of gene expression patterns. Initial biclustering reduces the search space in the high-dimensional microarray data. The least-squares error between fitting of gene pairs is minimized to extract a set of gene-gene interactions, involving transcriptional regulation of genes. The higher error values are eliminated to retain only the strong interacting gene pairs in the resultant gene regulatory subnetwork. Next the algorithm is extended to a generalized framework to enhance its capability. The methodology takes care of the higher-order dependencies involving multiple genes co-regulating a single gene, while eliminating the need for user-defined parameters. It has been applied to the time-series Yeast data, and the experimental results biologically validated using standard databases and literature.
Bayesian methods are often criticized on the grounds of subjectivity. Furthermore, misspecifiedpriors can have a deleterious effect on Bayesian inference. Noting that modelselection is effectively a test of many hypot...
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Bayesian methods are often criticized on the grounds of subjectivity. Furthermore, misspecified
priors can have a deleterious effect on Bayesian inference. Noting that model
selection is effectively a test of many hypotheses, Dr. Valen E. Johnson sought to eliminate
the need of prior specification by computing Bayes’ factors from frequentist test statistics.
In his pioneering work that was published in the year 2005, Dr. Johnson proposed
using so-called local priors for computing Bayes? factors from test statistics. Dr. Johnson
and Dr. Jianhua Hu used Bayes’ factors for model selection in a linear model setting. In
an independent work, Dr. Johnson and another colleage, David Rossell, investigated two
families of non-local priors for testing the regression parameter in a linear model setting.
These non-local priors enable greater separation between the theories of null and alternative
hypotheses.
In this dissertation, I extend model selection based on Bayes’ factors and use nonlocal
priors to define Bayes’ factors based on test statistics. With these priors, I have been
able to reduce the problem of prior specification to setting to just one scaling parameter.
That scaling parameter can be easily set, for example, on the basis of frequentist operating
characteristics of the corresponding Bayes’ factors. Furthermore, the loss of information by basing a Bayes’ factors on a test statistic is minimal.
Along with Dr. Johnson and Dr. Hu, I used the Bayes’ factors based on the likelihood
ratio statistic to develop a method for clustering gene expression data. This method has
performed well in both simulated examples and real datasets. An outline of that work is
also included in this dissertation. Further, I extend the clustering model to a subclass of
the decomposable graphical model class, which is more appropriate for genotype data sets,
such as single-nucleotide polymorphism (SNP) data. Efficient FORTRAN programming has
enabled me to apply the methodology to hundreds of
In this paper we assess the clustering results of gene expression (microarray) data by using different validation indices. We perform k-means clustering and evaluate the results by using three validation indices: Silh...
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In this paper we assess the clustering results of gene expression (microarray) data by using different validation indices. We perform k-means clustering and evaluate the results by using three validation indices: Silhouette, Davies-Bouldin's and our proposed BR index. For performing the experiments we use our implementation of these measures in MATLAB. From the comparison of the validation indices we can conclude that BR index has better decreasing tendency depending on the number of clusters than Davies Bouldin's index for yeast microarray dataset.
An efficient approach of cancer classification using microarray expression data by vector-valued regularized kernel function approximation (VVRKFA) method is presented in a true computer aided diagnosis framework. A f...
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An efficient approach of cancer classification using microarray expression data by vector-valued regularized kernel function approximation (VVRKFA) method is presented in a true computer aided diagnosis framework. A fast dimensionality reduction method based on maximum relevance minimum redundancy (MRMR) criteria is used to select very few genes so that both the classification accuracy and computational speed are enhanced. The experimental results are compared with support vector machines (SVM). It is observed that VVRKFA has achieved at least equal or better classification accuracy. This method also has the advantage that the separability of the data set can be observed in the label space.
Combinatorial interactions of transcription factors play a key role in modulating transcriptional regulatory mechanisms in Saccharomyces cerevisiae. Here we apply correlation analysis to search potential combinatorial...
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Combinatorial interactions of transcription factors play a key role in modulating transcriptional regulatory mechanisms in Saccharomyces cerevisiae. Here we apply correlation analysis to search potential combinatorial TF interactions with the integration of microarray data and ChIPchip data. Our results find that (ⅰ) eight significant cell cycle activators {Ace2, Fkh1, Fkh2, Mbp1, Ndd1, Swi4, Swi5, Swi6} are calculated to positively correlate with their respective targets;(ⅱ) seven TF pairs in nine important pairs have statistical correlation with their targets and three TF triplets in five triplets predicted by literature statistically correlate with shared targets. These results may highlight the enrichment of combinatorial TF interactions with statistical correlation. Besides, twenty-two TFs including the eight cell cycle activators are inferred to potentially interact with other TFs to regulate gene transcription in S. cerevisiae.
Recent technological progress on high-throughput measurements for gene expression such as microarray analysis enables us to collect time-series gene expression data for each of tens of thousands of genes. Although a g...
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ISBN:
(纸本)9781467322478
Recent technological progress on high-throughput measurements for gene expression such as microarray analysis enables us to collect time-series gene expression data for each of tens of thousands of genes. Although a genomic analysis with those data has identified key genes relating to various diseases, few results on estimation of gene regulatory networks with real microarray data are available so far. Recently, the immediately early response (IER) genes upon epidermal growth factor stimulation in a human breast cancer cell line, MCF-7, have been identified in which time-course microarray data were measured during 90 minutes and 63 IER genes were chosen from tens of thousands of genes by using statistical analysis. In this paper, we estimate the gene regulatory networks among the 63 IER genes. To this end, we apply an estimation method based on a mixed logic dynamical modeling developed in an earlier study to the microarray data. However, the original method is executable for continuous gene expression time-series data whereas the real microarray time-course data have very few time points. In addition, some presetting parameters in the model are critical for a successful result on a network estimation. Then, we add a preprocessing and Monte Carlo-based calculation for the original method.
The prediction of cancer progression is one of the most challenging problems in oncology. In this paper, we apply the penalized logistic model to microarray data in combination with co-expression genes to identify pat...
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ISBN:
(纸本)9781467311830
The prediction of cancer progression is one of the most challenging problems in oncology. In this paper, we apply the penalized logistic model to microarray data in combination with co-expression genes to identify patients with prostate cancer progression. Compared with conventional methods, penalized logistic regression (PLR) has some advantages such as providing an estimate of the probability in classification label, genetic interpretation of regression coefficients, and short computation time. We employed the top score pair (TSP) approach to select genes for PLR. The TSP method was originally proposed for binary classification of phenotypes according to the relative expression of one gene pair. In the proposed algorithm of this paper, we first identified co-expressed TSP genes and then used PLR to the microarray data for predicting prostate cancer. We applied the framework to the microarray analysis on prostate cancer progression. We have identified three gene pairs associated with prostate cancer progression for PLR model. We compared our approach with the standard classification techniques such as support vector machines (SVMs), Lasso, and Fisher discriminative analysis (FDA). We found that our method yielded better performance in terms of classification and prediction. Furthermore, it has the advantages to provide the underlying probability of predicting the classification, robust biomarker genes and interpretable regression coefficients.
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