Elevated ATF4 Expression in Odontogenic Keratocysts Epithelia: Potential Involvement in Tissue Hypoxia and Stromal M2 Macrophage Infiltration

Abstract

The aim of this study was to investigate the expression of the activating transcription factor 4 (ATF4) in odontogenic keratocysts (OKC), its association with hypoxia and M2-polarized macrophages infiltration, and its potential relationships with angiogenesis in OKC. The expression of ATF4, hypoxia-inducible factor 1α (HIF-1α), macrophage colony-stimulating factor (M-CSF), and receptor activator of nuclear factor κ-B ligand (RANKL) in OKC samples and normal oral mucosa (OM) was detected by immunohistochemistry. Meanwhile, microvessel density (MVD) was measured using antibody against CD31. M2-polarized macrophages were identified using double-staining for CD68+ and CD163+. The correlations of ATF4 with HIF-1α, M-CSF, and M2-polarized macrophages infiltration were determined by Spearman’s rank correlation test and hierarchical clustering. Human immortalized oral epithelial cells (HIOECs) were used in in vitro experiments. Our data showed that the expression of HIF-1α, ATF4, and M-CSF was significantly upregulated in the epithelium of OKC when compared with the OM. The expression of ATF4 was positively correlated with that of HIF-1α, M-CSF, MVD, and M2-polarized macrophages infiltration. Elevated expression of ATF4 in the epithelial lining of OKC may facilitate the M2 macrophages infiltration in response to hypoxia, leading to the development of OKC.

Increased M2 Isoform of Pyruvate Kinase in Fibroblasts Contributes to the Growth, Aggressiveness, and Osteoclastogenesis of Odontogenic Keratocysts

“…Immunohistochemistry was performed as described previously. 2,18 Briefly, all collected fresh samples were placed in 4% paraformaldehyde for fixation, followed by dehydration and paraffin wax embedding. Sliced paraffin sections (5 mm thick) were made for further procedures after dewaxing in xylene.…”

“…Odontogenic keratocysts (OKCs) are common cystic lesions occurring in jaw with a unique biological behavior, including local invasion, bone destruction, and a recurrence tendency. 1,2 Although both the epithelium and stroma of OKCs contribute to the pathologic processes of OKCs. 2,3 their pathologic mechanism is still poorly understood.…”

“…1,2 Although both the epithelium and stroma of OKCs contribute to the pathologic processes of OKCs. 2,3 their pathologic mechanism is still poorly understood.…”

Pyruvate Kinase M2 Mediates Glycolysis in the Lymphatic Endothelial Cells and Promotes the Progression of Lymphatic Malformations

“…3,20 During these processes, the proliferating ECs undergo vast transendothelial transport to perivascular cells, less oxidative stress, and continue sprouting even in hypoxia. 12 Therefore, ECs rely heavily on glycolysis for completing these processes, including proliferation, migration, and tubular formation.…”

“…As previously reported, 12 the whole-cell lysate was collected and the concentration of protein was determined by a bicinchoninic acid protein assay kit (catalog number P0012S; Beyotime, Shanghai, China). A total of 25 mg of protein from each group was separated on 10% SDSpolyacrylamide gels and was wetly transferred on polyvinylidene difluoride membrane by electrophoresis.…”