Fig 2: The clinical value of monoamine oxidase A (MAOA) and MAOB in colorectal cancer. (A) Visualization of the pan-cancer expression of MAOA and MAOB levels. Meta-Z analysis using the Prediction of Clinical Outcome from Genomic Profiles (PRECOG) website, which encompasses 39 distinct cancer types and 166 cancer expression datasets. (B,C) Forest plot showing the hazard ratios (HRs) and 95% confidence intervals for the association of MAOA (B) and MAOB (C) expression levels with disease-specific survival (DSS), disease-free survival (DFS), and overall survival (OS) in the five independent colorectal cancer (CRC) databases. The p-value was calculated.

Fig 3: Prognostic value of monoamine oxidase B (MAOB) in colorectal cancer. (A,B) Kaplan–Meier plots of overall survival (OS) curves (A) and disease-free survival (DFS) curves (B) for MAOB in colorectal cancer patients. The red line indicates high expression of MAOB, and the blue line indicates low expression. (C,D) Forest plots of the multivariate analysis for hazard ratios (HRs) using a Cox regression model in OS (C) and DFS (D). (E,F) Forest plots of univariate analysis for HRs using a Cox regression model in OS (E) and DFS (F). The p-value was calculated.

Fig 4: Immunohistochemical (IHC) results of monoamine oxidase A (MAOA) and MAOB expressions in a Taiwanese colorectal cancer cohort. (A) Representative pictures of expressions of MAOA and MAOB by IHC staining. An intensity score of 0 was defined as negative cytoplasmic staining, of 1 was defined as weak cytoplasmic staining, of 2 was defined as moderate cytoplasmic staining, and of 3 was defined as strong cytoplasmic staining. Scale bar indicated 100 µm. (B,C) Representative IHC staining images for MAOA (B) and MAOB (C) levels in paired normal (N) and tumor tissues (T) from selected colorectal cancer patients. The magnifying factor used in these representative pictures is ×400, and the intensity score of MAOA in the N part was 3. Scale bar indicated 100 µm. (D,E) Quantified results of cytoplasmic levels of MAOA (D) and MAOB (E) from IHC staining in primary colorectal cancer and corresponding normal colon mucosa. A total of 59 N/T paired data were included. The scores were calculated as the staining intensity score × percentage of stained cells.

Fig 5: The correlation of MAOB expression with epithelial-to-mesenchymal transition (EMT)-related genes in colorectal cancer patients. Visualization of expressions of MAOB and EMT-related genes in 287 colon cancer patients from The Cancer Genome Atlas (TCGA) cohort. Positive correlations between MAOB and mesenchymal markers and negative correlations between MAOB and epithelial markers. R indicates the Pearson’s R value, and *** indicates p < 0.0001.