Summary Background Glioma is the most frequent primary brain tumor and one of the most aggressive forms of cancer. Recently, numerous studies have focused on cannabinoids as a new therapeutic approach due to their antineoplastic effects through activation of the cannabinoid receptors. This study aimed to investigate the immunohistochemical expression level of cannabinoid type-1 receptors (CB1R) in human glioma samples and evaluate its clinicopathologic significance. Materials and methods We analyzed the expression of CB1R in 61 paraffin-embedded glioma and 4 normal brain tissues using automated immunohistochemical assay. CB1R expression was categorized into high versus low expression levels. Statistical analyses were performed to evaluate the association between CB1R and phosphorylated extracellular signal-related kinase (p-ERK) expression levels and the clinicopathologic features of glioma. Results Our results showed that CB1R immunopositivity was seen in 59 of 61 cases (96.7%). CB1R was down-expressed in glioma compared to normal brain tissues. However, CB1R expression was not correlated with clinicopathological parameters except for p-ERK. Conclusion Our findings indicate the down-expression of CB1R in glioma tissues when compared to non-cancerous brain tissues. This change in CB1R expression in gliomas should be further tested regardless of the clinicopathological findings to provide a therapeutic advantage in glioma patients.

Background Gliomas are the most frequent primary brain tumors and one of the most aggressive forms of cancer. Recently, numerous studies have focused on cannabinoids as a new cancer-therapeutic approach due to their antineoplastic effects through activation of the cannabinoid receptors, CB1 and CB2. The aim of this study was to investigate the expression levels of cannabinoid type-1 (CB1) receptors and phosphorylated extracellular signal-regulated kinase (p-ERK) in human glioma samples and evaluate their clinicopathologic significance. Materials and Methods We analyzed the expressions of CB1 receptors (CB1R) and p-ERK in 61 paraffin-embedded gliomas and 4 normal brain tissues using automated immunohistochemical assay. CB1R and p-ERK expressions were categorized into high versus low expression levels. Statistical analyses were performed to evaluate the association between CB1R and p-ERK expression levels and the clinicopathologic features and overall survival. Results Our results showed that CB1R is down-expressed in glioma tissues compared to normal brain tissues. However, the low expression of CB1R was found to be not related to the malignancy grade of gliomas. Conversely, higher expression of p-ERK was noted in gliomas compared to normal brain tissues, with no association observed with tumor grades. In addition, CB1R expression was not observed to be associated with clinicopathologic features of gliomas, except for p-ERK expression. Conclusion Our findings indicate a down-expression of CB1R and overexpression of p-ERK in glioma tissues when compared to non-cancerous brain tissues. This change in CB1R expression in gliomas may contribute to further research on the therapeutic effects of cannabinoids in human gliomas.