Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA100

Poster Communications

Decorin modulates melanoma cell migration: Diverse effects caused by differential glycanation of the protein core

C. Stock1, R. T. Owens2, F. Echtermeyer4, R. V. Iozzo3, D. G. Seidler1

1. Gastroenterology, Hepatology, Endocrinology, Hannover Medical School, D-30625 Hannover, Germany. 2. LifeCell Corporation, Branchburg, New Jersey, United States. 3. Pathology, Anatomy & Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States. 4. Anesthesiology and Intensive Care Medicine, Hannover Medical School, D-30625 Hannover, Germany.

The Na+/H+ exchanger NHE1 controls cellular pH homeostasis and is required for directional cell migration and invasion of extracellular matrices. In the dermis, the predominant proteoglycan is decorin (DCN), and its N-terminal glycosaminoglycan (GAG) chain is either of a dermatan (DS) or a chondroitin sulfate (CS) type. DS-DCN and the GAG chondroitin 6-sulfate (CS6S) inhibit migration and invasion of murine melanoma cells (B16V) on 3D collagen-rich C57BL/6 fibroblast cultures. DS-DCN reversibly reduces NHE1 activity and acidifies the cytosol while CS6S does not affect NHE1 activity but leads to an irreversible cytosolic acidification (Stock et al., 2011). To discover whether the DCN protein core alone (core) or DCN with different GAG structures (DS-DCN and CS-DCN) would act differently on melanoma cells, we compared their effects on single cell migration, morphology, NHE1 expression, cell surface pH, β-integrin expression, metabolic activity and apoptosis in B16V cells. Furthermore, we determined the DCN effect in 3D collagen-rich Dcn-/- fibroblast cultures supplemented with the different DCN preparations. We discovered that both DS-DCN and CS-DCN decreased migration speed and total distance covered within 6 hours. In contrast, the core stimulated motility accompanied by a more dendritic or spindle-like morphology, which could be counteracted by the specific NHE1 inhibitor KR-33028. Interestingly, NHE1 expression was significantly reduced by DS-DCN, but significantly increased by the core. Cell surface pH, known to modulate cell adhesion and migration, was irreversibly acidified by all three DCN preparations. Remarkably, DS-DCN treatment caused a shift in integrin expression from β3 to β1 integrin, whereas CS-DCN had no effect, indicating a specific impact of the GAG chain. This is supported by the finding that the protein core induced a shift from β1 to β3 integrin. None of the three DCN preparations affected metabolic activity or induced caspase 3/7 activity. When incorporated in Dcn-/- matrices, none of the three DCN preparations had an effect on cell migration; however, CS-DCN and core reduced invasion significantly. In summary, the core stimulated (i) NHE1 expression, (ii) acidification of the cell surface and (iii) cell motility in a 2D setting. However, both DS-DCN and CS-DCN, inhibited cell motility without affecting cell viability, and DS-DCN caused a significant decrease in NHE1 expression. In a more complex system where DCN was incorporated in a 3D matrix, differences in invasion depended on the GAG chain. This points to a possible therapeutic potential of DCN and GAGs and underscores the need to discover their (different) mechanism(s) of action. Also, the shifts in β integrin expression, induced by core and DS-DCN, deserve further study.

Where applicable, experiments conform with Society ethical requirements