Up-regulation of Cytoplasmic CD24 Expression Is Associated with Malignant Transformation but Favorable Prognosis of Colorectal Adenocarcinoma

Aim: Cluster of differentiation 24 (CD24) is known to be a putative marker of stem cell and tumor metastasis. This study aimed to verify the clinicopathological value of CD24 expression in colorectal adenocarcinoma (CRAC).

Materials and methods: A total of seven whole-tissue sections of malignant polyps including the sequence non-neoplastic colorectal tissue-adenoma-CRAC, 48 adenomas and 161 CRACs arranged as tissue microarray were examined by immunohistochemistry for CD24 protein expression. Association of CD24 expression with clinicopathological parameters were also studied.

Results: CD24 was not detected in normal mucosal epithelia. Cytoplasmic CD24 expression was higher in CRAC than in adenoma (p<0.001). In CRACs, cytoplasmic CD24 expression was inversely correlated with poor differentiation (grades 1 to 3), tumor size, and pathological TNM stage (I to III versus IV) (p=0.005, p=0.034, and p=0.006, respectively). Statistical correlations between high CD24 expression and longer overall and disease-free survival were found (p=0.023 and p=0.033, respectively).

Conclusion: Our findings suggest that up-regulation of CD24 expression in CRAC occurs at malignant transformation but is a marker of good prognosis, being down-regulated in pathological TNM stage IV. CD24 expression may be a challenging diagnostic marker in differentiating early invasive CRAC from adenoma and may serve as a prognostic marker in patients with CRAC.