Lymphocyte infiltration is an important feature of cancer. There is a complex network of chemokines that influence the degree and phenotype of lymphocyte infiltration, as well as the growth, survival, migration, and angiogenesis of tumor cells. High heterogeneity metastasis is a major obstacle to the treatment of breast cancer. Herein, we showed that O-GlcNAcylation of B lymphocyte–induced maturation protein-1 (Blimp-1) in lymphocytes inhibited the migration and invasion of breast cancer cells. It was found that Blimp-1 O-GlcNAcylation at Ser448 and Ser472 in lymphocytes promoted its nuclear localization, and blocked the bindings to three regions upstream of the ccl3l1 promoter to inhibit its expression. Decreased expression of CCL3L1 in lymphocytes not only decreased CCR5 expression in breast cancer cells, but also inhibited the membrane localization and activation of CCR5, thus blocking the migration and invasion of breast cancer cells in vitro. Therefore, O-GlcNAcylation of Blimp-1 in lymphocytes may serve as a new target for the treatment of metastatic breast cancer.
This study reveals a new mechanism by which the lymphatic system promotes breast cancer cell metastasis.
Metastasis and functional impairment of multiple organs are the main cause of deaths caused by cancer. Once cancer cells extravasate, they must encounter or induce a suitable microenvironment to initiate and maintain the growth of secondary tumors (1). Lymphocyte infiltration is an important feature of cancer, and myeloid and lymphoid immune cells can be recruited at all stages of breast cancer progression (2). Many kinds of cells are known to interact with cancer cells, which are important contributors to cancer progression. Currently, tumor-infiltrating immune cells that are known to have a complex relationship with tumor progression are dendritic cells (3, 4), neutrophils (5, 6), and macrophages (7–9), and they can promote or inhibit cancer progression. Tumor-specific T cells display a broad spectrum of (dys-)functional states, shaped by the multifaceted T-cell–intrinsic and -extrinsic factors that occur within the tumor microenvironment, and therapeutic reinvigoration of tumor-specific T cells has greatly improved clinical outcome of cancer treatment (10).
O-GlcNAc is a dynamic and reversible post-translational modification (PTM) on serine and threonine residues of nuclear and cytoplasmic proteins, and more than 25% of the O-GlcNAcylated proteins are involved in the transcriptional regulation (11). In recent years, more and more studies have shown that O-GlcNAcylation is closely related to the functions of the lymphatic system, and O-GlcNAcylation is regulated by glucose metabolism, then it can be regarded as a connecting link between the glycemic status and the immune response, and can function as a regulator of immunometabolism (12).
Blimp-1 is an important transcription factor that is highly expressed in various lymphocytes (13–18). Blimp-1 promotes the differentiation of B cells into plasma cells and plays a decisive role in antibody secretion (13). Blimp-1 influences the differentiation of T-cell lineages, promotes T-cell exhaustion in chronic infection, and plays an essential role in the maintenance of T-cell homeostasis (14). At the same time, Blimp-1 is closely related to the genesis and development of various lymphatic malignancies (15, 16). Blimp-1 has a variety of PTMs, such as ubiquitination and SUMOylation (19–23), which play an important role in the regulation of its structure and function. However, whether Blimp-1 is O-GlcNAcylated and the influence on its functions are unknown.
Here, we identified that Ser448 and Ser472 were the main O-GlcNAcylation sites of Blimp-1 in Jurkat cells, and demonstrated that the O-GlcNAcylation at these two sites promoted the nuclear localization of Blimp-1. By inhibiting the binding of Blimp-1 to the upstream of its promoter, O-GlcNAcylation reduced the expression of CCL3L1. We proposed that Blimp-1 O-GlcNAcylation inhibited the migration and invasion of breast cancer cells in vitro through the CCL3L1–CCR5 axis.
Materials and Methods
Jurkat, HEK293T, and HeLa cells were purchased from the ATCC. All the cell lines were authenticated by short tandem repeat profiling and tested for Mycoplasma contamination using Mycoprobe Mycoplasma Detection Kit (R&D system) more than once during this study. Cells were used within a maximum of 13 passages after thawing.
Reagents and antibodies
Reagents and specific antibodies used in this study are described previously in Supplementary Materials and Methods.
Plasmid construction and transfection
RGS-6xHis-BLIMP-1–pcDNA3.1- was a gift from Adam Antebi (Addgene plasmid # 52518; ref, 24). All point mutations of Blimp-1 were generated by site-directed mutagenesis through PCR using specific primers containing the corresponding mutations. All mutants were verified through DNA sequencing analysis. Transfection of HEK293T cells was performed with polyethylenimine (PEI; Sigma-Aldrich) following the manufacturer's instructions. Jurkat and HeLa cells were transfected by electroporation using Celetrix Transfection System.
Immunoprecipitation and western blotting analysis
Cell lysates were incubated with specific antibodies and lysis buffer. Subsequently, agarose beads (Sigma-Aldrich) were added and incubated. The beads were washed three times with PBS-T, 2×Loading Buffer was added, and the samples were heated at 95°C for 10 minutes. The resulting samples were separated by SDS-PAGE (10%) and transferred onto PVDF membranes. The membranes were then blocked with 5% BSA in TBS-T, incubated for anti-Blimp-1 or O-GlcNAc antibody, and subsequently incubated with secondary antibody. Immunoreactive proteins were detected using ECL Plus detection reagents (GE Healthcare) and detected using a ChemiDoc XRS System. The band intensity was evaluated using ImageJ software.
O-GlcNAc site identification using the Q exactive orbitrap LC/MS-MS
Liquid chromatography separation was performed on an Ultimate 3000 HPLC system (Thermo Fisher Scientific). A C18 homemade fused silica capillary column was used for peptide separation. Mass spectra for peptide identification or quantification were acquired using a Q Exactive Orbitrap mass spectrometer (Thermo Fisher Scientific). Peptide fragmentation was performed via high-energy collision dissociation with a set energy of 27 NCE.
Scratch wound (wound closure) migration assays
The scratch-wound assays were performed as described previously (25). Cells were seeded in complete medium at 3 × 105 (MCF-7) or 4 ×105 (MDA-MB-231) cells per well of a 6-well plate, incubated under standard conditions until 80% to 90% confluent. A linear wound was made with a p10 pipette tip. Cells were then resuspended in the culture supernatants of Jurkat cells overexpressing Blimp-1–WT, -S448A, -S472A and -2A. The area of wound closure was measured using Olympus cellSens software. To determine the percentage scratch closure, the cell-free space was measured using ImageJ software.
Cells were suspended in serum-free medium containing 0.1% BSA, and placed in Transwell inserts in which matrix was prepared (Corning) at a concentration of 1 × 105cells per insert. The culture supernatants of Jurkat cells overexpressing Blimp-1–WT, -S448A, -S472A and -2A were placed in the lower compartments. After 24 hours, migrated cells were fixed with 4% paraformaldehyde and stained with crystal violet (0.1%). The cells on the membrane were photographed and the average cell number was statistically analyzed.
Spheroid invasion assays
The Cultrex 3D culture spheroid cell invasion assays (Corning, 354480) were set up as per the manufacturer's instructions using the kit contents, including spheroid formation extracellular matrix (ECM) and invasion matrix. MDA-MB-231 cells were seeded in the spheroid formation ECM at 3,000 cells per well of a Costar 96-well ultra-low attachment plate followed by incubation for 72 hours. Spheroids were subsequently embedded in invasion matrix and vehicle or drug treatments were added. The area of invasion on days 0, 1, 2, 3, 4 was measured using Olympus cellSens software and was expressed normalized to the mean invasion of the vehicle control.
Intracellular calcium mobilization
Measurement of calcium mobilization by stimulation was performed as previously described (26). Briefly, MCF-7 cells (1 × 106/mL), which were untreated or cocultured with culture supernatants of Jurkat cells for 24 hours, were incubated in Tyrode's solution containing 5 μmol/L Fura-2 AM for 30 minutes at room temperature. The cells were subsequently washed and then resuspended at 1 × 106/mL in PBS, and 200 μL of cells were inoculated to a 96-well plate. Culture supernatants of Jurkat cells were added to the MCF-7 cells at 40 seconds with a final volume of 25 μL. Fluorescence was monitored at λex1 = 340 nm, λex2 = 380 nm, and λem = 510 nm. The data are presented as the relative ratio of fluorescence excited at 340 and 380 nm. Data were collected every 4 seconds. Values were graphed as 8-second interval averages minus the background change in fluorescence ratio seen in untreated cells. The first 8-second interval of each set was set at 0.
Statistical analysis was performed using Prism version 8.0.1 software (GraphPad Software). Data are expressed as mean ± SEM from at least three experiments. Differences between two groups were examined by one-way ANOVA. A P value of <0.05 was considered statistically significant.
The data generated in this study are available within the article and its Supplementary Data Files.
Blimp-1 interacts with OGT and is modified by O-GlcNAc
To investigate whether Blimp-1 is modified by O-GlcNAc, immunoprecipitation (IP) was performed with the Blimp-1 expressed in Jurkat cells, and it was then followed by Western blotting (WB) analysis with an RL2 antibody (IP/WB analysis), then a clear O-GlcNAc band was observed (Fig. 1A). We also detected a direct interaction between Blimp-1 and OGT in Jurkat cells by co-IP with an anti-Blimp-1 antibody combined with WB analysis (Fig. 1B).
Subsequently, we overexpressed His-Blimp-1 in 293T cells and purified it by an anti-His antibody. When an in vitro glycosylation experiment was performed, we found that Blimp-1 was modified with O-GlcNAc by HA-OGT obtained from E. coli (Fig. 1C). Then, the O-GlcNAcylated proteins expressed in 293T cells were labeled with Ac36AzGlcNAc, which were pulled down as previously described (27), and Blimp-1 was detected in the pull-down contents by WB analysis (Fig. 1D). Finally, it was found that co-expression with HA-OGT increased the O-GlcNAcylation of His-Blimp-1 expressed in 293T cells (Fig. 1E), and Blimp-1 O-GlcNAcylation was increased by TMG (an inhibitor for OGA; Fig. 1E). Although glucose increased the whole O-GlcNAcylation levels of 293T cells (Supplementary Fig. S1A), it inhibited the O-GlcNAcylation of His-Blimp-1 (Fig. 1E; Supplementary Fig. S1C). The reason might be that glucose increases the whole O-GlcNAcylation as a substrate for UDP-GlcNAc, but it inhibits Blimp-1 O-GlcNAcylation through other pathways. And similar results were observed in Jurkat cells (Supplementary Fig. S1B and S1D). The results above suggested that the Blimp-1 O-GlcNAcylation is dynamically regulated.
Ser448 and ser472 are the main O-GlcNAcylation sites on Blimp-1
To determine the main O-GlcNAcylation sites, recombinant His-Blimp-1 labeled with Ac36AzGlcNAc was purified from 293T cells, and then Ser448 and Ser472 were found to be the most promising O-GlcNAcylation sites by LC-MS/MS analysis (Fig. 2A; Supplementary Table S1). We then mutated Ser at the two sites to Ala, respectively (Blimp-1–S448A, Blimp-1–S472A) or simultaneously (Blimp-1–2A), and overexpressed them in Jurkat cells or 293T cells, then performed IP/WB analysis. And the results demonstrated that the O-GlcNAcylation levels of Blimp-1–S448A, -S472A and -2A were obviously decreased compared with Blimp-1–WT (Fig. 2B and C). Subsequently, we used Y289 L Gal1 and GalNAz to label and pull down the O-GlcNAcylated proteins as previously described (28). Compared with the amount of Blimp-1–WT obtained above, O-GlcNAc of Blimp-1–S448A, -S472A and -2A were significantly reduced (Fig. 2D). To sum up, Ser448 and Ser472 are the main O-GlcNAcylation sites on Blimp-1.
O-GlcNAcylation at ser448 and ser472 promotes nuclear localization of Blimp-1
We transfected Blimp-1–WT in Jurkat cells and 293T cells, which were then treated with OMSI-4 (an inhibitor for OGT), or TMG, and cytoplasmic and nuclear proteins were extracted, respectively. WB analysis on both cells showed that Blimp-1 in the nucleus was increased after TMG treatment, decreased after OMSI-4 treatment (Fig. 3A; Supplementary Fig. S2A). Then, we overexpressed Blimp-1–WT in Jurkat cells and HeLa cells, and immunofluorescence assays on both cells were performed after treating the cells with OMSI-4 or TMG. The results demonstrated that TMG promoted nuclear localization of Blimp-1, whereas OMSI-4 inhibited it (Fig. 3C; Supplementary Fig. S2B). Therefore, O-GlcNAcylation might promote the localization of Blimp-1 in nucleus.
Subsequently, it was investigated whether O-GlcNAcylation on Ser448 and Ser472 influences the localization of Blimp-1. We expressed HA-OGT together with Blimp-1–WT, -S448A, -S472A or -2A in Jurkat cells (Fig. 3B), respectively, then the cells were treated with (HG+TMG) or without (LG) glucose and TMG, and WB analysis was performed as above. It was found that under low O-GlcNAcylation condition (LG), Blimp-1–WT was mainly located in the cytoplasm. Under high O-GlcNAcylation condition (HG+TMG), Blimp-1–WT was mainly located in nucleus, whereas Blimp-1–S448A, Blimp-1–S472A, and Blimp-1–2A in the cytoplasm were notably increased. Then, an immunofluorescence assay was performed. Compared with the untreated group, the nucleus distribution of Blimp-1 overexpressed in Jurkat cells increased when treated with 10 μmol/L TMG and 25 mmol/L glucose. And the nucleus distribution of Blimp-1–S448A, -S472A or -2A decreased, especially Blimp-1–2A was mainly located in the cytoplasm, which was consistent with the results of WB analysis (Fig. 3D). And the WB performed in 293T cells (Supplementary Fig. S2A and S2C) or immunofluorescence assays in Hela cells (Supplementary Fig. S2B and S2D), respectively, obtained similar results as above. These results indicated that O-GlcNAcylation on Ser448 and Ser472 promoted the nuclear localization of Blimp-1.
O-GlcNAcylation at ser448 and ser472 of Blimp-1 inhibits CCL3L1 expression
To analyze the effects of Blimp-1 O-GlcNAcylation on the expression of target genes, we overexpressed Blimp-1–WT, -S448A, -S472A or -2A in Jurkat cells, respectively, and after treatment with 10 μmol/L TMG and 25 mmol/L glucose for 24 hours, transcriptomic analysis was performed. It was found that the transcription levels of the known targets of Blimp-1, such as IFN-γ (29), CIITA (30), and PAX5 (31), were not significantly changed, but the mRNA level of chemokine CCL3L1 was obviously increased (Supplementary Table S2). To verify the results, RT-qPCR was performed on Jurkat cells expressing Blimp-1–WT, -S448A, -S472A or -2A, respectively, followed by treatment with 10 μmol/L TMG and 25 mmol/L glucose for 24 hours (Fig. 4A), and ELISA was performed on the above cell culture supernatants (Fig. 4B). We found that Blimp-1–WT promoted CCL3L1 expression. O-GlcNAcylation at Ser448 and Ser472 abrogated the effect, whereas the influence of Ser472 O-GlcNAcylation was more dominant, and the O-GlcNAcylation at the two sites acted synergistically. Dual luciferase assays also demonstrated the promotion of Blimp-1 on the transcription of ccl3l1 promoter (Fig. 4C), which was inhibited by O-GlcNAcylation at Ser448 and Ser472, thereby inhibiting the transcription of CCL3L1.
To explore the mechanism by which O-GlcNAcylation at Ser448 and Ser472 inhibits CCL3L1 expression, we first performed double luciferase assays (Fig. 4D and E), and demonstrated a direct binding of Blimp-1–WT to the upstream 100–700 bp and 1,300–2,000 bp regions of the promoter of ccl3l1. Then, we predicted the binding sites of Blimp-1 and ccl3l1 through Jasper database (http://jaspar.genereg.net/; ref. 32; Fig. 4F), followed by designing primers (Supplementary Table S3) for the three candidate binding sites, and performed ChIP-qPCR assays using the primers above in Jurkat cells that expressed Blimp-1–WT or -mutants, respectively. The results showed that O-GlcNAcylation at Ser448 had no significant influence on the binding of Blimp-1 to the single site upstream of the promoter of ccl3l1, whereas loss of O-GlcNAcylation at Ser472 increased the binding abilities of Blimp-1 to all three regions, which were further enhanced by the 2A mutation (Fig. 4G). These results indicated that O-GlcNAcylation at Ser448 and Ser472 had a synergistic effect in inhibiting the binding of Blimp-1 to the promoter, thereby repressing the transcription of CCL3L1.
Blimp-1 O-GlcNAcylation at ser448 and ser472 abrogates CCL3L1–CCR5 axis
Because CCL3L1 is the most potent ligand for CCR5 (33, 34), we explored whether Blimp-1 O-GlcNAcylation has an influence on the CCL3L1–CCR5 axis. First, we incubated MCF-7 or MDA-MB-231 cells (both express the CCR5 receptor) with CCL3L1, and found that CCL3L1 increased the expression and membrane localization of CCR5 in a concentration-dependent manner (Supplementary Fig. S3).
Then, we cultured MCF-7 and MDA-MB-231 cells (35) with supernatants of Jurkat cells overexpressing Blimp-1–WT or -mutants, respectively, for 24 hours. It was demonstrated that overexpressing Blimp-1–WT in Jurkat cells had little influence on the expression of CCR5 at the transcriptional and translational levels (Fig. 5A–D). Compared with Blimp-1–WT, Blimp-1–S448A had no significant influence on the transcription and expression of CCR5, whereas Blimp-1–S472A promoted both, and the influences above were greatly enhanced by Blimp-1–2A (Fig. 5A–D).
Subsequently, we cocultured MCF-7 cells with or without supernatants separated form Jurkat cells overexpressing Blimp-1–WT or -mutants for 24 hours in advance, then performed Ca2+ influx assays by applying transient stimulus to MCF-7 cells with supernatants described above to evaluate the effect of Blimp-1 mutants on the activation of CCR5. It was found that without coculturing with supernatants for 24 hours, the Ca2+ influx on MCF-7 cells induced by Blimp-1–WT and mutants were not different, whereas Maraviroc (a CCR5 inhibitor) significantly inhibited the Ca2+ influx (Fig. 5E). The results suggested that the supernatants separated form Jurkat cells stimulated the Ca2+ influx mainly through the activation of CCR5 receptor. And, the activation was obviously enhanced by Blimp-1–S472A after coculturing MCF-7 cells with appropriate supernatants, although it was still weaker than Blimp-1–2A (Fig. 5F).
Finally, we investigated whether the membrane localization of CCR5 was promoted by Blimp-1–WT and -mutants. As demonstrated by WB (Fig. 5G) and IF analysis (Fig. 5H), the membrane localization of CCR5 was rarely enhanced by overexpressing Blimp-1–WT. It was promoted by Blimp-1–S448A and Blimp-1–S472A, and the promotion was further enhanced by Blimp-1–2A. Thus, the results demonstrated that O-GlcNAcylation at Ser448 and Ser472 of Blimp-1 abrogated CCL3L1–CCR5 axis, which was consistent with the role on CCL3L1 expression.
O-GlcNAcylation at ser448 and ser472 of Blimp-1 inhibits the migration and invasion of breast cancer cells
Studies have shown that CCR5 expresses on the cell surface of various tumors, such as breast (36), colorectal (37), prostatic (38), and gastric cancers (39), and it is closely related to the metastasis of tumors. Because O-GlcNAcylation at Ser448 and Ser472 of Blimp-1 abrogates the CCL3L1–CCR5 axis, we investigated the influences of Blimp-1 O-GlcNAcylation in Jurkat cells to the migration and invasion of breast cancer cells. We performed cell scratch assays by culturing MCF-7 or MDA-MB-231 cells with culture supernatants of Jurkat cells overexpressing Blimp-1–WT, or -mutants, respectively. And the results showed that Blimp-1–WT promoted the migration of the two cells above (Fig. 6A, B, D, and E), and Maraviroc and anti-CCL3L1 antibodies both weakened the promotion, which demonstrated that the influence induced by Blimp-1 was dependent on both CCL3L1 and CCR5. We also found that Blimp-1–S448A, Blimp-1–S472A enhanced the promotion of Blimp-1 to the migration of breast cancer cells, and Blimp-1–2A was the most efficient.
We then investigated the influence of Blimp-1 O-GlcNAcylation on the invasion of MDA-MB-231 cells, a highly invasive cell line, through Transwell assays and spheroid invasion assays. The results of both experiments showed that mutation at Ser448 and Ser472 of Blimp-1 boosted the invasion of MDA-MB-231 cells, and the invasion ability was further enhanced when the 2A mutant was compared with the single mutant (Fig. 6C, F, and G). Again, we showed that the increased invasiveness of the cell depended on the activation of the CCL3L1–CCR5 axis by using Maraviroc and an anti-CCL3L1 antibody. Therefore, the results above suggested that Blimp-1 O-GlcNAcylation at Ser448 and Ser472 inhibited the migration and invasion of breast cancer cells through abrogating the CCL3L1–CCR5 axis.
Blimp-1 is an important transcription factor that not only plays various important roles in the immune system (1), but also exerts significant impacts on the differentiation of epidermal cells (17) and embryos (18). But a mechanistic insight is still lacking. In particular, there are few researches to explain how it regulates various targets precisely in different cells. PTM is an important pathway for the regulation of protein function. Different modification types and certain modifications at specific sites both have a crucial impact on protein function. Our results showed that O-GlcNAcylation of Blimp-1 in Jurkat cells inhibited its binding to the ccl3l1 promoter, thereby inhibiting the transcription of CCL3L1 (Fig. 4). However, inhibition to the transcription of the known targets such as CIITA (30) and PAX5 (31) was not significantly affected (Supplementary Table S2), suggesting that the selective regulation on transcription of the targets may be affected by the PTMs of Blimp-1. The results suggest that the regulatory mechanism of Blimp-1 can be explored from the perspective of PTMs.
In transcriptional assays, we observed that O-GlcNAcylation-deficient mutants of Blimp-1 promoted the CCL3L1 promoter more efficiently than the Blimp-1–WT (Fig. 4). These results are unexpected considering that Blimp-1 mutants are more concentrated in the cytoplasm. A possible model that could explain these results would be that Blimp-1 not only promotes the expression of CCL3L1 directly, but it may also mediate the transcription of CCL3L1 in an indirect manner by regulating the expression of other transcription factors. In another words, the O-GlcNAcylation–competent Blimp-1 located in the nucleus may inhibit the expression of other factors that promote CCL3L1 transcription, thus reducing its promotion effect on CCL3L1. Therefore, whether other transcription factors, which regulate the transcription of CCL3L1, are regulated by Blimp-1 remain to be further studied.
We did explore the potential crosstalk between O-GlcNAcylation and other PTMs, but no significant influence of O-GlcNAcylation on phosphorylation (Supplementary Fig. S4) or ubiquitination was found (Supplementary Fig. S5A). SUMOylation is known to accelerate the proteasomal degradation of Blimp-1 (20), but we found that O-GlcNAcylation of Blimp-1 had no notable effect on its stability (Supplementary Fig. S5B). One possible explanation is that the study investigated the function of Blimp-1 O-GlcNAcylation in T lymphoma cells, and there is still much room to study whether the main O-GlcNAcylation sites of Blimp-1 are different in normal T cells and other cells, as well as the role of site-specific O-GlcNAcylation.
Tumor chemokine networks mainly act in two aspects (40): Chemokines control lymphocyte infiltration in tumor tissues, and influence the metastatic and proliferation of tumor cells. Previous studies have shown that the expression of CCR5 receptors in various tumor cells is closely related to the invasion and migration of tumors (36–39). These studies suggest that inhibition of the CCL5–CCR5 axis can effectively inhibit tumor metastasis. Our work (Figs. 4–6) has showed that Blimp-1 in lymphocytes regulates the expression of chemokine CCL3L1, which has a positive effect on CCR5 of tumor cells, thus promoting tumor metastasis. Our results complement the related ligands of CCR5 in promoting tumor metastasis, and further demonstrate the importance and feasibility of CCR5–CCR5 ligands as a therapeutic target for metastatic tumors.
The kinetics of O-GlcNAcylation is related to glucose metabolism, and it plays an important role in the immune system. Therefore, O-GlcNAcylation has been regarded as a link between the cellular metabolic pathways, especially the glucose state, and the immune response, and as a regulator of immune metabolism. Relying on metabolism to regulate cell function is a feature of cancer cells, which is known as the Warburg effect characterized by increased glucose uptake and enhanced aerobic glycolysis (41). However, this results in a low glucose microenvironment around tumor cells, which can promote tumor progression (42) and drug resistance (43). The O-GlcNAcylation of Blimp-1 expressed by lymphocytes was decreased in hypoglycemic environment, which is more conducive to the activation of CCL3L1–CCR5 axis, thus promoting tumor metastasis. The results contribute to a deeper understanding of the complex regulatory mechanisms of O-GlcNAcylation in tumors. Not only the O-GlcNAcylation in the tumor itself, but also that of other cells in the microenvironment have vital effects on the occurrence and development of tumors.
In sum, we have revealed the relationship between Blimp-1 O-GlcNAcylation and tumor metastasis, and clarified the mechanism. Our work demonstrated the important role of the CCL3L1–CCR5 axis in tumor metastasis, suggesting that both Blimp-1 O-GlcNAcylation and the CCL3L1–CCR5 axis could be targeted to inhibit tumor metastasis.
X.-S. Ye reports grants from National Key R&D Program of China, National Natural Science Foundation of China, and Beijing Outstanding Young Scientist Program during the conduct of the study. No disclosures were reported by the other authors.
Y.-F. Chen: Conceptualization, data curation, formal analysis, validation, investigation, visualization, methodology, writing–original draft. G.-C. Shao: Software, formal analysis. J. Li: Validation. A.-Q. Yang: Methodology. J. Li: Formal analysis, methodology, writing–review and editing. X.-S. Ye: Conceptualization, resources, data curation, formal analysis, supervision, funding acquisition, methodology, project administration, writing–review and editing.
This work was financially supported by the grants from the National Key R&D Program of China (2018YFA0507602), the National Natural Science Foundation of China (81821004, 21738001), and the Beijing Outstanding Young Scientist Program (BJJWZYJH01201910001001).
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