Expression of MMP-2 correlates with increased angiogenesis in CNS metastasis of lung carcinoma

Matrix metalloproteinases (MMP) have been implicated in increased invasive and metastatic potential of tumors, possibly via interactions with the extracellular matrix and angiogenesis. This study investigates the relationship between MMP-2 immunoexpression and angiogenesis in a series of lung carcinomas metastatic to the central nervous system (CNS). Twenty eight metastatic carcinoma cases with adequate brain-tumor interface were identified from the archives at the Moffitt Cancer Center. MMP-2 expression was determined by immunohistochemistry using an antibody directed against pro and active forms (NeoMarkers). Similarly, microvessels were identified on parallel sections with anti-CD34 antibody (Biogenix). Angiogenesis profiles within the tumor and at the CNS/tumor interface were morphometrically assessed by the Image Pro Plus image analysis system. Briefly, CD34 positive vessels were quantitated and correlated with presence or absence of MMP-2 expression in the tumor. Mean microvessel area (MMVA) and mean microvessel number (MMVN) were assessed within areas of brain-tumor interface and within the tumor and expressed as a ratio relative to the tumor. Sixteen (57.14%) metastatic tumors were strongly immunoreactive for MMP-2, while 12 (42.86%) were negative. MMP-2 positive tumors had a higher MMVA and MMVN ratio at the CNS/tumor interface in comparison to MMP-2 negative neoplasms. MMP-2 expression thus appears to confer enhanced vascular proliferation particularly at the brain-tumor interface which would support the contention of enhanced capability of growth and invasion within the CNS, possibly modulated by MMP2. The relationship between MMP-2 expression and angiogenesis has been previously reported and its biological and therapeutic implications remain the focus of investigations.