A network-based biomarker approach for molecular investigation and diagnosis of lung cancer

In this study, a systems biology approach integrating microarray gene expression profiles and protein-protein interaction information was proposed to develop a network-based biomarker for molecular investigation into the network mechanism of lung carcinogenesis and diagnosis of lung cancer. The network-based biomarker consists of two protein association networks constructed for cancer samples and non-cancer samples.Based on the network-based biomarker, a total of 40 significant proteins in lung carcinogenesis were identified with carcinogenesis relevance values (CRVs). In addition, the network-based biomarker, acting as the screening test, proved to be effective in diagnosing smokers with signs of lung cancer.A network-based biomarker using constructed protein association networks is a useful tool to highlight the pathways and mechanisms of the lung carcinogenic process and, more importantly, provides potential therapeutic targets to combat cancer.Cancer, the complex disease of uncontrolled cell growth, is one of the leading causes of human death worldwide and the deaths from cancer are projected to continue rising [1,2]. Among all types of cancer, the most commonly diagnosed, as well as the most common cause of cancer deaths, is lung cancer, with a mortality rate as high as 80-85% within 5 years [1,3]. Lung cancer is categorized into two main types: small cell lung carcinoma (SCLC) and non-small cell lung carcinoma (NSCLC). NSCLCs are subcategorized into three main subtypes: squamous cell carcinoma, adenocarcinoma, and large cell carcinoma [4]. Previous research has shown that these major histological types of lung cancer are associated with cigarette smoking [5]. In light of this, much research has been devoted to investigating the molecular alterations which ensued from cigarette smoking and the mechanism that links cigarette smoking to lung cancer. Spira et al. used DNA microarray to compare the gene expressions of large-airway epithelial cells from nonsmokers a