Inducible nitric oxide synthase activity correlates with lymphangiogenesis and vascular endothelial growth factor‐C expression in head and neck squamous cell carcinoma

Abstract

Nitric oxide (NO) is a diatomic free radical molecule that has been implicated in tumour angiogenesis and progression of head and neck squamous cell carcinoma (HNSCC). However, the mechanism underlying the effect of NO on tumour spread remains largely unknown. Tumour lymphangiogenesis has recently received considerable attention and there is increasing evidence that it is relevant for metastasis to lymph nodes in HNSCC. Here, we study the correlation between inducible NOS synthase (iNOS) activity and lymphangiogenesis in a series of 60 HNSCCs and the possible involvement of the lymphangiogenic factor vascular endothelial growth factor (VEGF)-C. HNSCC presenting with lymph node metastasis had a significantly higher lymphatic vessel density in both the tumour mass and the peritumour area (p = 0.006 and p = 0.001, respectively). Similarly, tumours with lymph node metastasis showed greater lymphatic vessel area than tumours with no lymph node involvement (p = 0.001 for intratumour lymphatics and p < 0.001 for peritumour lymphatics). iNOS activity measured in specimens from the tumour periphery correlated strongly with both lymphatic vessel density and lymphatic vessel area (p = 0.01, rs = 0.45 and p < 0.001, rs = 0.725, respectively). Conversely, these correlations were not observed in specimens from the tumour core. In addition, VEGF-C mRNA expression was significantly elevated in tumours with high iNOS activity (p = 0.008, rs = 0.563), and VEGF-C expression correlated positively with the presence of lymph node metastases (p = 0.03). In vitro, in the A431 human squamous carcinoma cell line, exogenous and endogenous stimulation of the iNOS pathway led to up-regulation of VEGF-C, which was blocked by the NOS inhibitor L-NNA. Taken together, our results indicate that iNOS activity may promote lymphangiogenesis and spread to lymph nodes in HNSCC, with the possible involvement of VEGF-C.

Inducible nitric oxide synthase expression in melanoma: implications in lymphangiogenesis

“…NO regulates the vasomotor activity of lymphatic microvessels, 8,28 inducing dilation, and it may act as a lymphangiogenetic factor through interaction with VEGF-C, as previously demonstrated in breast cancer and head and neck squamous cell carcinomas. 5,29 Interestingly, VEGF-C-overexpressing melanomas showed enhanced tumor angiogenesis, suggesting a coordinated 30,31 CD105 is an endothelial marker that reacts uniquely with endothelial cells of newly formed vessels, and, specifically of immature tumor blood vessels. 32 Thus, microvessel density evaluated using a marker of activated endothelial cells, such as CD105, may depict the time-course of the neoangiogenetic process within the tumor.…”

“…6,7 In addition, more recent observations indicate that NO is involved in the regulation of lymphatic vessels permeability and flow 8 and we have recently demonstrated that iNOS activity correlated with lymphangiogenesis and spread to lymph nodes in head and neck squamous cell carcinoma. 5 It is possible that in the tumor microenvironment NO stimulates angiogenesis and/or lymphangiogenesis cooperatively with other proangiogenic and lymphangiogenic growth factors.…”

“…1 In cancer, although high levels of NO may exert cytostatic or cytotoxic functions, the constitutive production of low levels of intracellular NO has been associated with tumor growth. [2][3][4][5] Tumor-cell-derived NO has been proposed to be an important mediator of tumor angiogenesis and metastasis formation by directly inducing vessel dilation, promotion of blood flow and vascular permeability and endothelial cell proliferation through upregulation of vascular endothelial growth factor (VEGF) and basic fibroblastic growth factor. 6,7 In addition, more recent observations indicate that NO is involved in the regulation of lymphatic vessels permeability and flow 8 and we have recently demonstrated that iNOS activity correlated with lymphangiogenesis and spread to lymph nodes in head and neck squamous cell carcinoma.…”

Advances in the research on lymphangiogenesis in carcinoma tissues (Review)

“…Human intratumoral lymphatic vessels consist of only 2 or 3 LVECs, which are small, irregular and collapsed. Consequently, these vessels are thought to provide no activities, although some of them show positive staining for proliferating cell nuclear antigens (9). A possible explanation for this finding is the rapid proliferation and tumor tissue division in human cancer cells, which increases the interstitial hydrostatic pressure and blocks the lumen of new lymphatic vessels (10).…”

Myeloid Cells and Lymphangiogenesis

“…For example, VEGF-C expression correlates with COX-2 expression in breast cancer (Zhang et al 2008), and VEGF-C expression is stimulated by the inflammatory mediators interleukin-1b, TNF-a, and COX-2 and its induced prostaglandins (Ristimaki et al 1998;Su et al 2004). In head and neck cancer, the activity of inducible nitric oxide synthase (iNOS) is found to correlate with VEGF-C expression, lymphangiogenesis, and lymph node metastasis, and the human epidermoid carcinoma cell line A431 up-regulates VEGF-C on nitric oxide (NO) treatment (Franchi et al 2006). iNOS can be produced by tumor or stromal cells, including macrophages, and is induced by inflammatory cytokines or LPS.…”