World Journal of Oncology, ISSN 1920-4531 print, 1920-454X online, Open Access
Article copyright, the authors; Journal compilation copyright, World J Oncol and Elmer Press Inc
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Original Article

Volume 17, Number 1, February 2026, pages 34-51


Clinical Significance and Potential Molecular Mechanisms of Angiotensin-Converting Enzyme 2 in Colorectal Cancer

Figures

↓  Figure 1. The expression level of ACE2 protein in different cell types based on single-cell RNA sequencing. (a) t-SNE plot showing the distribution of various cell types (activated B cells, fibroblasts, CD4+ naive T cells, macrophages, CD4+ effector T cells, malignant cells, memory B cells, monocytes, naive B cells, plasma cells, Tregs, unassigned) in the dataset. (b) Bar chart representing the normalized expression level of ACE2 protein across different cell types. (c) t-SNE plot highlighting ACE2 expression levels, with red dots indicating higher expression and green dots indicating lower expression. (d) InferCNV analysis for malignancy assessment, with a color gradient indicating expression levels and malignancy likelihood. ACE2: angiotensin-converting enzyme 2; t-SNE: t-distributed stochastic neighbor embedding; Tregs: regulatory T cells; CRC: colorectal cancer; NK: natural killer.
Figure 1.
↓  Figure 2. The expression levels of MKI67 and ACE2 proteins in colon tissue based on spatial transcriptomics. (a) Heat maps depicting regional scores of epithelial cells, stromal cells, and immune cells, illustrating the distribution of each component’s score. (b) Spatial distribution of epithelial cells, stromal cells, and immune cells, with different colors labeling the locations of the three cell components. (c) Heat maps showing the spatial distribution of MKI67 and ACE2 gene expression, where colors correspond to gene expression levels. (d) Bar chart of ACE2 H-scores in epithelial, stromal, and immune cells, comparing ACE2 expression levels across the three cell components. ACE2: angiotensin-converting enzyme 2; MKI67: marker of proliferation Ki-67.
Figure 2.
↓  Figure 3. CRC ACE2 mRNA samples were obtained from a multicenter high-throughput dataset, including 2,275 CRC samples and 1,269 non-CRC colorectal samples. (a) Flow plot. (b) ACE2 expression in bulk mRNA data. (c) Egger’s test: detection of publication bias (P = 0.027); sensitivity and specificity analysis. ACE2: angiotensin-converting enzyme 2; AUC: area under the curve; CRC: colorectal cancer; GEO: Gene Expression Omnibus; TCGA: The Cancer Genome Atlas; SMD: standardized mean difference; SROC: summary receiver operating characteristic; CI: confidence interval; GTEx: Genotype Expression.
Figure 3.
↓  Figure 4. The expression level of ACE2 protein in CRC and peritumor colon tissues based on IHC. (a-c) Representative images of ACE2 protein expression in peritumor colon tissues. (d-f) Representative images of ACE2 protein expression in CRC tissues. In panels (a-f), the magnifications of the three images of each panel are 100, 200, and 400 respectively. (g) ACE2 protein expression (P = 1.29 × 10-12). (h) Receiver operating characteristic (ROC) curve with area under the curve (AUC) of ACE2 protein expression in CRC tissues. ACE2: angiotensin-converting enzyme 2; CRC: colorectal cancer; IHC: immunohistochemistry; TPR: true positive rate; FPR: false positive rate.
Figure 4.
↓  Figure 5. The expression of ACE2 was associated with CD8 and PD-L1. (a) Correlation analysis of ACE2 expression value and pathological pattern. (b) Correlation analysis of ACE2 expression value and PD-L1 positive rate (%). (c) Correlation analysis of PD-L1 and CD8 positive rate (%). ACE2: angiotensin-converting enzyme 2; PD-L1: programmed death ligand 1.
Figure 5.
↓  Figure 6. Correlation and enrichment analysis of ACE2 expression with immune cell types and CD8 T cell activity. (a) Bar plot showing the correlation (R) and P value of ACE2 expression with various immune cell types (Th1 cells, T cells, CD8 T cells, Th2 cells, TFH, Tem, Treg, T helper cells, Tgd, Tcm, Th17 cells, B cells), with color indicating P value significance. (b) Box plot comparing the enrichment score of CD8 T cells between low and high ACE2 expression groups (P = 0.0018). (c) Scatter plot showing the relationship between ACE2 expression (Log2(TPM + 1)) and CD8 T-cell enrichment score, with Spearman correlation (R = -0.186, P = 5.46 × 10-5). ACE2: angiotensin-converting enzyme 2; Tcm: T central memory; Tem: T effector memory; TFH: T follicular helper; Tgd: T gamma delta; Th1: T helper 1; Th17: T helper 17; Th2: T helper 2; Tregs: regulatory T cells; TPM: transcripts per million.
Figure 6.

Tables

↓  Table 1. The Datasets Used in the Research
 
Study Non-CRC CRC
CRC: colorectal cancer; TCGA: The Cancer Genome Atlas; GTEx: Genotype Expression.
GPL10558 129 89
GPL15207 23 37
GPL570 239 645
GPL6480 14 206
GPL96 104 268
GSE103512 12 57
GSE113513 14 14
GSE115261 10 10
GSE141174 3 3
GSE156355 6 6
GSE15781 20 22
GSE20842 65 65
GSE25071 4 46
GSE28000 6 5
GSE41011 12 19
GSE44076 98 98
GSE47063 4 14
GSE87211 160 203
TCGA_GTEx 349 471

 

↓  Table 2. The Relationships of ACE2 Expression With the Clinicopathologic Parameters by Interpretation of the Immunohistochemistry
 
Clinicopathological features ACE2 expression
N Mean SD P (t) t/F
BRAF: B-Raf proto-oncogene, serine/threonine kinase; KRAS: Kirsten rat sarcoma viral oncogene homolog; NRAS: neuroblastoma RAS viral oncogene homolog; ACE2: angiotensin-converting enzyme 2; SD: standard deviation; P (t): P value from t-test; t/F: t-statistic/F-statistic.
Tissue
  Non-cancer 75 0.973 0.803 < 0.001 -8.262
  Cancer 66 4.917 3.804
Gender
  Male 34 4.069 3.756 0.547 -0.675
  Female 32 5.244 3.886
Age
  < 60 years 16 3.769 3.685 0.594 -1.322
  ≥ 60 years 46 5.235 3.865
Tumor stage
  T1 - T2 7 5.629 4.129 0.924 0.521
  T3 - T4 59 4.832 3.792
Node stage
  N0 42 5.224 3.773 0.993 0.866
  N1 - N2 24 4.379 3.877
Metastasis stage
  M0 62 5.024 3.719 0.441 0.903
  M1 4 3.25 5.318
Pathological stage
  Stage I - II 56 5.155 3.805 0.527 1.211
  Stage III - IV 10 3.58 3.699
Pathological type
  Tubular 52 5.577 3.832 0.008 3.603
  Mucinous 14 2.464 2.548
Vascular invasion
  No 59 4.59 3.689 0.395 -2.078
  Yes 7 7.671 3.907
Neurological invasion
  No 59 4.649 3.848 0.033 -2.265
  Yes 7 7.171 2.632
Tumor nodule
  Single 58 4.978 3.846 0.824 0.171
  Multiple 7 4.714 3.917
Tumor size (cm)
  < 5 32 5.216 3.567 0.374 0.617
  ≥ 5 34 4.635 4.047
BRAF mutation (V600E)
  No 61 5.095 3.846 0.066 1.339
  Yes 5 2.74 2.599
KRAS mutation
  No 44 4.739 3.919 0.522 -0.535
  Yes 22 5.273 3.623
NRAS mutation (G12C/D/S)
  No 63 4.881 3.801 0.938 -0.347
  Yes 3 5.667 4.623
NRAS mutation (Q61R/L/H/K)
  No 62 5.094 3.837 0.04 2.785
  Yes 4 2.175 1.855