CD93 gene polymorphism is associated with disseminated colorectal cancer

Abstract

Purpose: Cluster of differentiation 93 (CD93) is involved in apoptosis and inflammation and has a suggested role in angiogenesis, and all of which are involved in the development and dissemination of cancer. We evaluated the expression of CD93 and the association with two single nucleotide polymorphisms (SNPs), rs2749812 and rs2749817, as possible biomarkers in colorectal cancer (CRC).

Methods: Tissue levels and plasma levels of CD93 were measured using an enzyme-linked immunosorbent assay (ELISA). Expression of CD93 was determined by immunohistochemistry, western blot and gene expression analysis. Genotype frequencies were established for the SNPs by real-time polymerase chain reaction (PCR), and the association with tumour stage and survival was analysed.

Results: Total CD93 levels were 82% higher (P < 0.001) in tumours compared to matched normal tissues. Mean levels of soluble CD93 in plasma were 30% lower (P < 0.001) in the patients compared to the controls. The T/T genotype of SNP rs2749817 was more common in stage IV patients, with consequently higher risk of CRC death (T/T vs. C/C and C/T; hazard ratio (HR) = 1.73, 95% confidence interval (CI) = 1.11-2.67, P = 0.014), and was associated with a higher risk of CRC recurrence after radical operation (T/T vs. C/C and C/T; HR = 2.07, CI = 1.22-3.51, P = 0.007).

Conclusions: We showed that the T/T genotype of SNP rs2749817 is associated with disseminated cancer at diagnosis and an increased recurrence rate after radical operation. Patients with this genotype may benefit from early identification.

Fig. 1

Immunohistochemical staining of CD93 in human CRC (a, b) and normal tissue (c). In tumour tissue, CD93 is present in endothelial cells located around small (a) and large blood vessels (b). In normal tissue, only faint CD93 expression in some vascular endothelial cells located around blood vessels is seen (c), scale bar = 20 μm

Fig. 2

Western blot analysis of CD93 protein expression (~75 and ~110 kDa) in four representative specimens of human colorectal tumour and matched normal tissues; normal tissue (N) and tumour tissue (T)

Fig. 3

Tissue expression of total CD93 (ng/mg) from tumour and matched normal tissues in 101 CRC patients examined by ELISA; asterisks indicate P < 0.001

Fig. 4

Plasma expression of soluble CD93 (ng/mL) from 110 CRC patients and 106 healthy controls examined by ELISA; asterisks indicate P < 0.001

Fig. 5

Kaplan-Meier curve describing cancer-specific survival estimates among CRC patients according to C/C (middle blue line), C/T (upper red line) and T/T (lower green line) genotypes of SNP rs2749817; P = 0.013

Fig. 6

Kaplan-Meier curve describing disease-free survival estimates among CRC patients in stage I–III after R0 resection according to C/C (middle blue line), C/T (upper red line) and T/T (lower green line) genotypes of SNP rs2749817; P = 0.047