Elevated Expression of Caveolin-1 Reflects a Poor Prognosis in Patients With Primary Central Nervous System Lymphomas

Caveolin-1 (Cav-1) is a component of the vesicle-like structure of the plasma membrane called caveolae. Cav-1 is involved in the transport of substances from the plasma membrane to the intracellular space of various cells. It has been reported that it is involved in the growth mechanisms, angiogenesis, and immune evasion of various malignant tumors. In the present study, the relationships between Cav-1 expression in primary central nervous system lymphomas (PCNSLs) and clinicopathological characteristics were investigated to clarify the role of Cav-1 in the progression of PCNSLs and patient prognosis. The expression of Cav-1 was assessed in 39 PCNSLs (CNS diffuse large B-cell lymphomas) using immunostaining, and its prognostic significance was evaluated. Cav-1 expression by PCNSLs was evaluated using the histoscore (H-score). The H-score for Cav-1 in PCNSLs ranged from 0 to 90 (median 20); there were 12 cases showing no score (H-score 0), 11 cases with a low score (0 < H-score < 20), and 16 cases with a high score (H-score ≥ 20). Survival was significantly lower in patients with high H-scores than in those with no score and low H-scores (p < 0.01), and in patients with high numbers of Cav-1-positive vessels than in those with low numbers of Cav-1-positive vessels (p < 0.05). Cav-1 positivity in tumor cells was correlated with the Ki-67 labeling index and the number of Cav-1-positive vessels. These results suggest that Cav-1 may be involved in the proliferation and angiogenesis of PCNSL cells. The present study also demonstrated that overexpression of Cav-1 in PCNSLs is associated with tumor progression and a poor patient prognosis.