Dataset Information

Phosphatidylcholine-specific phospholipase C inhibition down- regulates CXCR4 expression and interferes with proliferation, invasion and glycolysis in glioma cells.

ABSTRACT:

Background

The chemokine receptor CXCR4 plays a crucial role in tumors, including glioblastoma multiforme (GBM), the most aggressive glioma. Phosphatidylcholine-specific phospholipase C (PC-PLC), a catabolic enzyme of PC metabolism, is involved in several aspects of cancer biology and its inhibition down-modulates the expression of growth factor membrane receptors interfering with their signaling pathways. In the present work we investigated the possible interplay between CXCR4 and PC-PLC in GBM cells.

Methods

Confocal microscopy, immunoprecipitation, western blot analyses, and the evaluation of migration and invasion potential were performed on U87MG cells after PC-PLC inhibition with the xanthate D609. The intracellular metabolome was investigated by magnetic resonance spectroscopy; lactate levels and lactate dehydrogenase (LDH) activity were analyzed by colorimetric assay.

Results

Our studies demonstrated that CXCR4 and PC-PLC co-localize and are associated on U87MG cell membrane. D609 reduced CXCR4 expression, cell proliferation and invasion, interfering with AKT and EGFR activation and expression. Metabolic analyses showed a decrease in intracellular lactate concentration together with a decrement in LDH activity.

Conclusions

Our data suggest that inhibition of PC-PLC could represent a new molecular approach in glioma biology not only for its ability in modulating cell metabolism, glioma growth and motility, but also for its inhibitory effect on crucial molecules involved in cancer progression.

SUBMITTER: Mercurio L

PROVIDER: S-EPMC5397108 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Publications

Phosphatidylcholine-specific phospholipase C inhibition down- regulates CXCR4 expression and interferes with proliferation, invasion and glycolysis in glioma cells.

Mercurio Laura L Cecchetti Serena S Ricci Alessandro A Pacella Aurora A Cigliana Giovanni G Bozzuto Giuseppina G Podo Franca F Iorio Egidio E Carpinelli Giulia G

PloS one 20170419 4

<h4>Background</h4>The chemokine receptor CXCR4 plays a crucial role in tumors, including glioblastoma multiforme (GBM), the most aggressive glioma. Phosphatidylcholine-specific phospholipase C (PC-PLC), a catabolic enzyme of PC metabolism, is involved in several aspects of cancer biology and its inhibition down-modulates the expression of growth factor membrane receptors interfering with their signaling pathways. In the present work we investigated the possible interplay between CXCR4 and PC-PL ...[more]

PMID: 28423060

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Project description:IntroductionOverexpression on plasma membrane of human epidermal growth factor receptor 2 (HER2) is reported in 25% to 30% of breast cancers. Heterodimer formation with cognate members of the epidermal growth factor receptor (EGFR) family, such as HER3 and EGFR, activates abnormal cell-signalling cascades responsible for tumorigenesis and further transcriptional HER2 gene upregulation. Targeting the molecular mechanisms controlling HER2 overexpression and recycling may effectively deactivate this feedback-amplification loop. We recently showed that inactivation of phosphatidylcholine-specific phospholipase C (PC-PLC) may exert a pivotal role in selectively modulating the expression on the membrane of specific receptors or proteins relevant to cell function. In the present study, we investigated the capability of PC-PLC inhibition to target the molecular mechanisms controlling HER2 overexpression on the membrane of breast cancer cells by altering the rates of its endocytosis and lysosomal degradation.MethodsLocalization on the membrane and interaction of PC-PLC with HER2, EGFR, and HER3 were investigated on HER2-overexpressing and HER2-low breast cancer cell lines, by using confocal laser scanning microscopy, flow cytometry, cell-surface biotinylation, isolation of lipid rafts, and immunoprecipitation experiments. The effects of the PC-PLC inhibitor tricyclodecan-9-yl-potassium xanthate (D609) on HER2 expression on the membrane and on the levels of overall HER2, HER2-HER3, and HER2-EGFR contents were monitored in the HER2-overexpressing SKBr3 cells, after either transient or continuous receptor engagement with anti-HER2 monoclonal antibodies, including trastuzumab. Changes of HER2 expression and cell proliferation were examined in SKBr3, BT-474, and MDA-MB-453 cells continuously exposed to D609 alone or combined with trastuzumab.ResultsPC-PLC selectively accumulates on the plasma membrane of HER2-overexpressing cells, where it colocalizes and associates with HER2 in raft domains. PC-PLC inhibition resulted in enhanced HER2 internalization and lysosomal degradation, inducing downmodulation of HER2 expression on the membrane. Moreover, PC-PLC inhibition resulted in strong retardation of HER2 reexpression on the membrane and a decrease in the overall cellular contents of HER2, HER2-HER3, and HER2-EGFR heterodimers. The PC-PLC inhibitor also induced antiproliferative effects, especially in trastuzumab-resistant cells.ConclusionsThe results pointed to PC-PLC inhibition as a potential means to counteract the tumorigenic effects of HER2 amplification and complement the effectiveness of current HER2-targeting therapies.

Dataset Information

Phosphatidylcholine-specific phospholipase C inhibition down- regulates CXCR4 expression and interferes with proliferation, invasion and glycolysis in glioma cells.

Background

Methods

Results

Conclusions

Publications

Phosphatidylcholine-specific phospholipase C inhibition down- regulates CXCR4 expression and interferes with proliferation, invasion and glycolysis in glioma cells.

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