A Comparison of Two-Stage Approaches Based on Penalized Regression for Estimating Gene Networks

Prediction of survival risks with adjusted gene expression through risk-gene networks

MOTIVATION

Network-based analysis of biomedical data has been extensively studied over the last decades. As a successful application, gene networks have been used to illustrate interactions among genes and explain the associated phenotypes. However, the gene network approaches have not been actively applied for survival analysis, which is one of the main interests of biomedical research. In addition, a few previous studies using gene networks for survival analysis construct networks mainly from prior knowledge, such as pathways, regulations and gene sets, while the performance considerably depends on the selection of prior knowledge.

RESULTS

In this paper, we propose a data-driven construction method for survival risk-gene networks as well as a survival risk prediction method using the network structure. The proposed method constructs risk-gene networks with survival-associated genes using penalized regression. Then, gene expression indices are hierarchically adjusted through the networks to reduce the variance intrinsic in datasets. By illustrating risk-gene structure, the proposed method is expected to provide an intuition for the relationship between genes and survival risks. The risk-gene network is applied to a low grade glioma dataset, and produces a hypothesis of the relationship between genetic biomarkers of low and high grade glioma. Moreover, with multiple datasets, we demonstrate that the proposed method shows superior prediction performance compared to other conventional methods.

AVAILABILITY AND IMPLEMENTATION

The R package of risk-gene networks is freely available in the web at http://cdal.korea.ac.kr/NetDA/.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Regression-Based Network Estimation for High-Dimensional Genetic Data

Given the continuous advancement in genome sequencing technology, large volumes of gene expression data can be easily obtained. However, the corresponding increase in genetic information necessitates adoption of a new approach for network estimation. Data dimensions increase with the progress in genome sequencing technology, thereby making it difficult to estimate gene networks by causing multicollinearity. Furthermore, such a problem also occurs when hub nodes exist, where gene networks are known to have regulator genes that can be interpreted as hub nodes. This study aims at developing methods that demonstrate good performance when handling high-dimensional data with hub nodes. We propose regression-based approaches as feasible solutions in this article. Elastic-net and adaptive elastic-net penalty regressions were applied to compensate for the disadvantages of existing regression-based approaches employing LASSO or adaptive LASSO. Experiments were performed to compare the proposed regression-based approaches with other conventional methods. We confirmed the superior performance of the regression-based approaches and applied it to actual genetic data to verify the suitability to estimate gene networks. As results, robustness of the proposed methods was demonstrated with respect to high-dimensional gene expression data.