N-myc downstream-regulated gene 1 can promote vasculogenic mimicry and angiogenesis in urothelial carcinoma

Abstract

Urothelial carcinoma (UC) of the bladder is a common cause of cancer-related death worldwide. Vasculogenic mimicry (VM) is a process by which the malignant cells can generate vascular-like structures formed of periodic acid-Schiff (PAS) positive/CD31 negative extracellular matrix independent of angiogenesis and thus promotes tumor progression. N-myc downstream-regulated gene 1 (NDRG1) is a protein that can modulate tumor angiogenesis; however, its role in regulating tumor angiogenesis and VM formation has not been previously investigated in UC. This study aims to evaluate the role of intra-tumor microvessel density (MVD) (as a surrogate measure of angiogenesis), VM, and NDRG1 in UC and their correlation with different clinicopathologic features, then assess the correlation between them in UC. Sixty specimens of UC of the bladder were included. PAS-CD31 immunohistochemical double staining method was used to evaluate the intra-tumor MVD and VM. Immunohistochemical expression of NDRG1 was also examined. VM and NDRG1 expression were detected in 41.7% and 83.3% of UC specimens respectively. The mean of intra-tumor MVD, VM area, and NDRG1 was significantly higher in tumors with higher grade, lymphovascular invasion, and higher T stage. NDRG1 expression was positively correlated with MVD and VM. We can suggest that MVD, VM, and NDRG1 may serve as poor prognostic markers for UC. The positive correlation between NDRG1 and both MVD and VM may provide the first evidence that NDRG1 can induce tumor angiogenesis and VM in UC which may offer a novel pathway for further therapeutic strategies.

Keywords: MVD; NDRG1; Urothelial carcinoma; Vasculogenic mimicry.

Fig. 1

Microvessel density in urothelial carcinoma (scale bar 100 μm). Low microvessel density in low-grade urothelial carcinoma (a, ×200 and b, ×400). High microvessel density in high-grade urothelial carcinoma (c, ×200 and d, ×400)

Fig. 2

Vasculogenic mimicry (VM) by periodic acid–Schiff (PAS)-CD31 double staining in urothelial carcinoma (scale bar 100 μm). PAS +ve /CD31 −ve patterned matrix type of vasculogenic mimicry arranged in back-to-back loops and arches that surrounded packets of tumor cells (arrow) (a, ×400). Vasculogenic mimicry by ImageJ analysis; the patterns have been automatically detected, highlighted, and quantified (b, ×400). Red blood cells are focally noted within the lumen of PAS +ve /CD31 −ve patterned matrix type of vasculogenic mimicry (arrow) (c, ×400). VM structures are interconnected with CD31+ endothelial-lined blood vessels in some areas (d, ×400). Urothelial carcinoma negative for vasculogenic mimicry and contains only CD31+ endothelial-lined blood vessels (arrows) (e, ×200 and f, ×400)

Fig. 3

Immunohistochemical expression of NDRG1 in urothelial carcinoma (scale bar 100 μm). Weak expression of NDRG1 in low-grade non-invasive urothelial carcinoma (a, ×200 and b, ×400). Moderate expression of NDRG1 in low-grade urothelial carcinoma infiltrating the lamina propria (c, ×200 and d, ×400). Strong expression of NDRG1 in high-grade urothelial carcinoma infiltrating the muscle layer (e, ×200 and f, ×400). Strong expression of NDRG1 in high-grade urothelial carcinoma infiltrating the perivesical fat (g, ×200 and h, ×400)