Ein neuartiger Fluoreszenzfarbstoff als Point-of-Care Diagnostik zur Einschätzung des Rezidivrisikos von Meningeomen

Deletion of the short arm of chromosome 1 (1p) represents an independent biomarker for increased recurrence risk in meningiomas. The alkaline phosphatase gene is located on chromosome 1p36.1-p34. Intracellular absence of the alkaline phosphatase enzyme in meningiomas correlates with 1p deletion. Conventional molecular genetic screening methods for 1p deletion are resource-consuming and infrastructure-demanding, hence alternative screening methods are required.The fluorescent probe AlkaPhos represents a novel tool to detect intracellular alkaline phosphatase activity by allowing for the distinction of product and substrate emission. In this study, the authors sought to evaluate the capability of AlkaPhos to detect alkaline phosphatase in meningioma cells and correlate observations with fluorescence in situ hybridization (FISH), loss of heterozygosity (LOH) and conventional histochemical analysis.

Via microscopic fluorescent ratio measurements, specificity of AlkaPhos to detect alkaline phosphatase was evaluated on BEN-MEN-1 cells. Conventional histochemical analysis was performed on the same tumors as a reference for intracellular presence of alkaline phosphatase. AlkaPhos was applied to primary meningioma cell cultures and results were compared to FISH, LOH and histochemical results from the corresponding tumors.

AlkaPhos specifically indicated alkaline phosphatase activity in BEN-MEN-1 cell cultures.In 11/14 (78%) samples, matching results for 1p deletion in FISH and AlkaPhos reaction were obtained. For LOH, matching results with AlkaPhos reaction was recorded in 10/14 (71%) of tumor samples. In 10/14 (71%) samples, matching results in histochemical analysis and AlkaPhos testing were obtained. AlkaPhos correctly identified 8/8 (FISH) and 7/7 (LOH) (100%) tumors with 1p deletion and LOH of 1p, whereas histochemical analysis could only identify 6/8 (75%, FISH) and 5/7 (71%, LOH), respectively.

AlkaPhos bears the potential for a future diagnostic tool to identify absence of alkaline phosphatase in meningiomas and thereby indicate 1p deletion. Compared to histochemical analysis, AlkaPhos tended to be superior in correctly identifying tumors with 1p deletion and LOH of 1p. Further evaluation of AlkaPhos on a larger number of native meningioma samples is required to approach routine clinical application.