Sp2‐Iminosugar α‐glucosidase inhibitor 1‐C‐octyl‐2‐oxa‐3‐oxocastanospermine specifically affected breast cancer cell migration through Stim1, β1‐integrin, and FAK signaling pathways

Abstract

Aberrant glycosylation changes on many glycoproteins are often related to cancer progression and metastasis. sp2 -Iminosugar-type castanospermine analogues, inhibitors of α-glucosidases, have been reported to exhibit antitumor activity. However, their effects on cell migration and the underlying molecular mechanism are not fully understood. Here, we investigated the effect of the pseudo-C-octyl glycoside 2-oxa-3-oxocastanospermine derivatives (CO-OCS) on breast cancer cells (MCF-7 and MDA-MB-231 cells), and MCF-10A mammary normal cell lines. We showed that CO-OCS treatment results in the drastic decrease of breast cancer cell migration without affecting cell proliferation. Furthermore, CO-OCS significantly reduced both the expression of β1-integrin, which is a crucial interacting partner of Focal Adhesion Kinase (FAK), and the phosphorylation rates of FAK and ERK1/2. CO-OCS also drastically reduced Ca2+ entry through Store Operated Channels (SOC). Orai1 and Stim1, two N-glycosylated proteins, are involved in Store-Operated Calcium Entry (SOCE), and are essential for breast tumor cell migration. Our results showed that CO-OCS decreased the expression, at the protein level, of Stim1 without affecting that of Orai1. Moreover, cell migration and SOCE were attenuated by CO-OCS as well as when Stim1 was silenced. In contrast, in MCF-10A cells, CO-OCS slightly reduced cell migration, but was without effect on gene expression of Stim1, Orai1, β1-integrin, or FAK and ERK1/2 activation. Our results provide strong evidence for a significant effect of CO-OCS on breast cancer cell migration and support that this effect was associated with β1-integrin, Stim1, and FAK signaling pathways.