Tumor necrosis is associated with increased alpha_vbeta₃ integrin expression and poor prognosis in nodular cutaneous melanomas

Tumor necrosis and apoptotic activity are considered important in cancer progression, but these features have not been much studied in melanomas. Our hypothesis was that rapid growth in cutaneous melanomas of the vertical growth phase might lead to tissue hypoxia, alterations in apoptotic activity and tumor necrosis. We proposed that these tumor characteristics might be associated with changes in expression of cell adhesion proteins leading to increased invasive capacity and reduced patient survival. A well characterized series of nodular melanoma (originally 202 cases) and other benign and malignant melanocytic tumors (109 cases) were examined for the presence of necrosis, apoptotic activity (TUNEL assay), immunohistochemical expression of hypoxia markers (HIF-1 α, CAIX, TNF-α, Apaf-1) and cell adhesion proteins (α_vβ₃ integrin, CD44/HCAM and osteopontin). We hypothesized that tumor hypoxia and necrosis might be associated with increased invasiveness in melanoma through alterations of tumor cell adhesion proteins. Necrosis was present in 29% of nodular melanomas and was associated with increased tumor thickness, tumor ulceration, vascular invasion, higher tumor proliferation and apoptotic index, increased expression of α_vβ₃ integrin and poor patient outcome by multivariate analysis. Tumor cell apoptosis did also correlate with reduced patient survival. Expression of TNF-α and Apaf-1 was significantly associated with tumor thickness, and osteopontin expression correlated with increased tumor cell proliferation (Ki-67). Tumor necrosis and apoptotic activity are important features of melanoma progression and prognosis, at least partly through alterations in cell adhesion molecules such as increased α_vβ₃ integrin expression, revealing potentially important targets for new therapeutic approaches to be further explored