Monoamine Oxidase B Expression Correlates with a Poor Prognosis in Colorectal Cancer Patients and Is Significantly Associated with Epithelial-to-Mesenchymal Transition-Related Gene Signatures

Abstract

Monoamine oxidases (MAOs) including MAOA and MAOB are enzymes located on the outer membranes of mitochondria, which are responsible for catalyzing monoamine oxidation. Recently, increased level of MAOs were shown in several cancer types. However, possible roles of MAOs have not yet been elucidated in the progression and prognosis of colorectal carcinoma (CRC). We therefore analyzed the importance of MAOs in CRC by an in silico analysis and tissue microarrays. Several independent cohorts indicated that high expression of MAOB, but not MAOA, was correlated with a worse disease stage and poorer survival. In total, 203 colorectal adenocarcinoma cases underwent immunohistochemical staining of MAOs, and associations with clinicopathological parameters and patient outcomes were evaluated. We found that MAOB is highly expressed in CRC tissues compared to normal colorectal tissues, and its expression was significantly correlated with a higher recurrence rate and a poor prognosis. Moreover, according to the univariate and multivariate analyses, we found that MAOB could be an independent prognostic factor for overall survival and disease-free survival, and its prognostic value was better than T and N stage. Furthermore, significant positive and negative correlations of MAOB with mesenchymal-type and epithelial-type gene expressions were observed in CRC tissues. According to the highlighted characteristics of MAOB in CRC, MAOB can be used as a novel indicator to predict the progression and prognosis of CRC patients.

Monoamine Oxidase (MAO) as a Potential Target for Anticancer Drug Design and Development

“…However, the rate of reoccurrence is about 30% due to distant metastasis, particularly in late-stage patients [ 54 ]. Yang et al [ 55 ] studied MAO expression in colorectal cancer using in silico analysis and tissue microarrays. In 203 cases of colorectal adenocarcinoma, MAO-B demonstrated high expression in cancer tissues in comparison to normal tissues.…”

“…The results showed that high MAO-B expression in tissues related well with high reoccurrence rate and poor prognosis. On the other hand, MAO-B expression had a positive correlation with epithelial-to-mesenchymal-transition-related gene expression in CRC tissues [ 55 ].…”

Genomic Expression Profiling of Colorectal Cancer in Silico

“…Elevation of MAOB activity in cells resulted in induction of oxidative stress in association with mitochondrial dysfunction. Yi-Chieh Yang et al [35] found that MAOB is highly expressed in CRC tissues compared to normal colorectal tissues, and its overexpression was signi cantly associated with a higher recurrence rate and poorer prognosis. However, in this study, we found that the expression of MAOB were not signi cantly associated with prognosis, which might be owing to the different samples used for the research; thus, this point deserves further investigation.…”

Near-Infrared MAO A Inhibitor (NMI) Outperformed FDA-Approved Chemotherapeutic Agents in Brain and Other Cancers: A Bioinformatic Analysis of NCI60 Screening Data

“…Yang et al found that MAO A expression slightly decreased in colorectal cancer tumor tissue compared to normal colon tissue; MAO B expression correlated with poor prognosis in colorectal cancer [14].…”