Fig 2: Expression profile of AOX1. (A) Bar graph depicting AOX1 mRNA and protein expression in 37 human tissues in the Human Protein Atlas (HPA) database. (B) Comparison of AOX1 expression in 31 different kinds of cancers and matched normal control samples. T stands for tumor, and N stands for normal. Clear cell renal cell carcinoma (ccRCC) patient data were extracted from The Cancer Genome Atlas Kidney Renal Clear Cell Carcinoma (TCGA-KIRC) using UCSC Xena. *p < 0.05. (C) Target–disease association analysis revealing AOX1-associated diseases.

Fig 3: Genetic alterations of AOX1 gene in clear cell renal cell carcinoma (ccRCC) patients. (A) Heat map showing the correlation between AOX1 DNA copy number alteration (CNA) and its expression. (B) Violin plot showing AOX1 expression in different CNA groups. CNAs were defined as follows: no change (0), heterozygous deletion (–1), homozygous deletion (–2), amplification (1), and high amplification (2). n = 23, n = 401, and n = 78 for –2/–1, 0, and 1/2 groups respectively. (C) Kaplan–Meier curve of ccRCC patients subgrouped by AOX1 DNA CNAs shows worse overall survival in ccRCC patients with copy number deletions in the AOX1 gene. n = 23 and n = 479 for CNA < 0 and CNA = 0, respectively. (D) Methylation levels (beta-value) of CpG site in AOX1 DNA locus subgrouped by AOX1 expression level. n = 125 and n = 177 for AOX1 low expression and high expression, respectively. (E) Heat map showing the correlation between AOX1 expression and CpG site methylation level of AOX1 DNA. Color bar indicates Pearson’s correlation coefficient.

Fig 4: Validation of AOX1 gene dysregulation in clear cell renal cell carcinoma (ccRCC). (A) Violin plot showing significantly lower AOX1 expression in ccRCC tissues compared with normal control kidney tissues in The Cancer Genome Atlas Kidney Renal Clear Cell Carcinoma (TCGA-KIRC) dataset. n = 72 and n = 533 for control and ccRCC, respectively. (B) Receiver operating characteristic (ROC) curve showing the predictive value of AOX1 expression for ccRCC patients. AUC, area under the curve. (C) Representative images of AOX1 immunohistochemical staining in normal kidney tissues (control) and ccRCC tissues. Scale bar is 50 µm. (D) Violin plot for quantification of AOX1 staining intensity in panel (C) showing significantly lower AOX1 intensity in ccRCC tissues compared with normal kidney tissues (control). n = 6 and n = 10 for control and ccRCC, respectively. (E) Representative images of AOX1 immunochemical staining in normal kidney tissues demonstrating AOX1 expression in proximal tubules (left panel) and distal tubules (right panel). Scale bar is 50 µm in upper left panel and 20 µm in other panels. (F) Violin plot for quantification of AOX1 staining intensity in panel (E) shows the strongest AOX1 staining in proximal tubules. n = 6 for each group.