Ribitol enhances matriglycan of α-dystroglycan in breast cancer cells without affecting cell growth.

The laminin-binding glycan (matriglycan) on α-dystroglycan (α-DG) enables diverse roles, from neuronal development to muscle integrity. Reduction or loss of matriglycan has also been implicated in cancer development and metastasis, and specifically associated with high-grade tumors and poor prognoses in breast cancers. Hyperglycosylation of α-DG with LARGE overexpression is shown to inhibit cancer cell growth and tumorigenicity. We recently demonstrated that ribitol, considered to be a metabolic end-product, enhances matriglycan expression in dystrophic muscles in vivo. In the current study, we tested the hypothesis that ribitol could also enhance matriglycan expression in cancer cells. Our results showed for the first time that ribitol is able to significantly enhance the expression of matriglycan on α-DG in breast cancer cells. The ribitol effect is associated with an increase in levels of CDP-ribitol, the substrate for the ribitol-5-phosphate transferases FKRP and FKTN. Direct use of CDP-ribitol is also effective for matriglycan expression. Ribitol treatment does not alter the expression of FKRP, FKTN as well as LARGEs and ISPD which are critical for the synthesis of matriglycan. The results suggest that alteration in substrates could also be involved in regulation of matriglycan expression. Interestingly, expression of matriglycan is related to cell cycle progression with highest levels in S and G2 phases and ribitol treatment does not alter the pattern. Although matriglycan up-regulation does not affect cell cycle progression and proliferation of the cancer cells tested, the novel substrate-mediated treatment opens a new approach easily applicable to experimental systems in vivo for further exploitation of matriglycan expression in cancer progression and for therapeutic potential.