O-GlcNAcylation homeostasis controlled by calcium influx channels regulates multiple myeloma dissemination

Abstract

Background Multiple myeloma (MM) cell motility is a critical step during MM dissemination throughout the body, but how it is regulated remains largely unknown. As hypercalcemia is an important clinical feature of MM, high calcium (Ca2+) and altered Ca2+ signaling could be a key contributing factor to the pathological process. Methods Bioinformatics analyses were employed to assess the clinical significance of Ca2+ influx channels in clinical specimens of smoldering and symptomatic MM. Functional and regulatory roles of influx channels and downstream signaling in MM cell migration and invasion were conducted and experimental MM dissemination was examined in a xenograft mouse model using in vivo live imaging and engraftment analysis. Results Inhibition of TRPM7, ORAI1, and STIM1 influx channels, which are highly expressed in MM patients, and subsequent blockage of Ca2+ influx by CRISPR/Cas9 and small molecule inhibitors, effectively inhibit MM cell migration and invasion, and attenuate the experimental MM dissemination. Mechanistic studies reveal a nutrient sensor O-GlcNAcylation as a downstream regulator of Ca2+ influx that specifically targets cell adhesion molecules. Hyper-O-GlcNAcylation following the inhibition of Ca2+ influx channels induces integrin α4 and integrin β7 downregulation via ubiquitin-proteasomal degradation and represses the aggressive MM phenotype. Conclusions Our findings unveil a novel regulatory mechanism of MM cell motility via Ca2+ influx/O-GlcNAcylation axis that directly targets integrin α4 and integrin β7, providing mechanistic insights into the pathogenesis and progression of MM and demonstrating potential predictive biomarkers and therapeutic targets for advanced MM.

Pathophysiological role of calcium channels and transporters in the multiple myeloma

“…It is generally believed that the BM microenvironment provides support for MM cell growth and survival and for the acquisition of aggressive phenotypes. High Ca 2+ and altered Ca 2+ signals in the BM microenvironment may be a key contributing factor to the pathological process [ 68 ]. Therefore, Ca 2+ channels and transporters, which are molecular participants of Ca 2+ homeostasis, could be significantly involve with MM progression in term of MM cell motility and dissemination.…”

“…Samart et al observed that the expression of Ca 2+ influx channels (such as TRPM7) in patient-derived MM cells are upregulated compared with normal plasma cells in a bioinformatics database. They used the CRISPR/Cas9 system to repress TRPM7 gene expression in MM cells, which can significantly inhibit the migration and invasion of MM cells [ 68 ]. Such result can reduce the intravasation of MM cells from the BM into nearby blood vessels and for their subsequent extravasation into distant tissues [ 69 , 70 ].…”

“…Such result can reduce the intravasation of MM cells from the BM into nearby blood vessels and for their subsequent extravasation into distant tissues [ 69 , 70 ]. In addition, vitro and vivo experiments show that TRPM7, Orai1 and Stim1 (Orai1 and Stim1 will be described in detail in SOCE) mediated Ca 2+ influx regulate MM cell motility and dissemination by orchestrating O-GlcNAylation homeostasis that targets integrin α4 and integrin β7 [ 68 ]. In summary, TRPM7 is a key regulator of MM cell motility and dissemination, and may be a potential predictive biomarker and therapeutic targets for advanced MM.…”

“…In addition, Stim1 could regulate the motility and dissemination of diffuse large B-cell lymphoma (DLBCL) cells and MM cells [ 16 ] [ 68 ] [ 126 ] Endoplasmic reticulum Orai1 Plasma membrane, SKF-96365 DES 2-APB Inhibitor Inhibitor Inhibitor Silencing Orai1 reduces cell viability, leading to apoptosis and cell cycle arrest of MM cells. And Orai1 regulates the motility and dissemination of diffuse large B-cell lymphoma (DLBCL) cells and MM cells [ 16 ] [ 68 ] [ 111 ] [ 126 ] Cytosol AnCoA4 TRPC1 Plasma membrane – – Knockout of TRPC1 inhibits the death of MM cells [ 132 ] Mitochondrial Ca 2+ transporters VDAC1 Mitochondrion, Nucleus – – VDAC1 promotes the growth of MM cells, accelerates the development of MM, and affects the prognosis of patients [ 17 ] [ 144 ] MCU Mitochondrion Ruthenium red Inhibitor MCU can reduce MM bortezomib resistance and promote MM cell apoptosis [ 151 ] [ 152 ] …”

O-GlcNAcylation in Chronic Lymphocytic Leukemia and Other Blood Cancers

“…Public databases suggest O-GlcNAcylation is actually reduced in myeloma as OGA was significantly higher in 133 primary myeloma samples compared to normal plasma cells from 5 normal donors with similar OGT expression ( 184 , 185 ). Myeloma microenvironments contain high levels of calcium released by osteolysis.…”