Preventive Effects of Dental Pulp Stem Cell-conditioned Media on Anti-RANKL Antibody-Related Osteonecrosis of the Jaw.

Medication-related osteonecrosis of the jaw is a serious disease occurring in patients with cancer and osteoporosis, who are undergoing treatment with antiresorptive agents (ARAs) such as bisphosphonate (BP) or denosumab, an antibody targeting receptor activator of NF-κB ligand. Recently, stem cell-based therapy has been shown to be effective in preventing the development of bisphosphonate-related osteonecrosis of the jaw. However, studies on denosumab-related osteonecrosis of the jaw (DRONJ) remain limited. Here, the efficacy of treatment with dental pulp stem cell conditioned media (DPSC-CM) in preventing DRONJ in a murine model was evaluated. Local administration of DPSC-CM into the extraction socket of a mouse with DRONJ decreased the number of empty osteocyte lacunae and the prevalence of ONJ. In tissues surrounding the extraction sockets in the DPSC-CM-treated group, the expression of inflammatory cytokines was attenuated and that of osteogenesis-related molecules was enhanced compared to that in the control group. Further, the expression of Wnt signaling molecules, which had been suppressed, was improved. These findings collectively suggest that DPSC-CM prevents ONJ development in a murine DRONJ model.

Mutational landscape of oral mucosal melanoma based on comprehensive cancer genomic profiling tests in a Japanese cohort.

OBJECTIVES: Oral mucosal melanoma (OMM) is a rare but aggressive melanoma subtype. Due to its rarity, the genomic landscape of OMM remains unknown despite a relatively thorough understanding of the genetic profile of cutaneous melanoma (CM). In this study, we analyzed the genomic mutational profiles of Japanese patients with OMM and compared them with those of patients with nose/sinuses mucosal melanoma (NMM) and CM to identify potential therapeutic targets. MATERIALS AND METHODS: We extracted clinical and genomic information of patients with OMM (n = 15), NMM (n = 63), and CM (n = 413) who underwent comprehensive genomic profiling tests under the National Health Insurance between June 2019 and November 2023 from the Center for Cancer Genomics and Therapeutics database. RESULTS: The most frequent genomic alteration identified in OMM was RICTOR (40%) followed by CDK4 (33.3%), MDM2 (33.3%), KDR (30%), KIT (26.7%), and NF1 (26.7%). CDK4 and MDM2 were co-amplified. Gene alterations in MYC and NRAS were the highest in patients with NMM, followed by those with CM, and no MYC alteration was observed in patients with OMM. BRAF V600 mutation, which is frequently observed in patients with CM (23.2%) were only present in 1.6% of patients with NMM and none in patients with OMM. CONCLUSION: This study clarified the genetic differences between OMM and NMM, and the first to report the frequent occurrence of RICTOR amplification in OMM. This analysis offers insights into the development of personalized therapeutics for OMM.

Hyperthermia maintains death receptor expression and promotes TRAIL-induced apoptosis.

BACKGROUND: Tumor necrosis factor-related apoptosis-inducing ligand activates apoptotic pathways and could potentially be used in anticancer treatments. However, oral squamous cell carcinoma cells are known to be resistant to tumor necrosis factor-related apoptosis-inducing ligand-induced cell death. It has been previously reported that hyperthermia upregulates tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis in other cancers. As such, we evaluated whether hyperthermia upregulates tumor necrosis factor-related apoptosis-inducing ligand-mediated apoptosis in a tumor necrosis factor-related apoptosis-inducing ligand-resistant oral squamous cell carcinoma cell line. METHODS: The oral squamous cell carcinoma cell line HSC3 was cultured and divided into hyperthermia and control groups. We investigated the antitumor effects of recombinant human tumor necrosis factor-related apoptosis-inducing ligand using cell proliferation and apoptosis assays. Additionally, we measured death receptor 4 and 5 levels, and determined death receptor ubiquitination status, as well as E3 ubiquitin ligase targeting of death receptor in both hyperthermia and control groups before recombinant human tumor necrosis factor-related apoptosis-inducing ligand administration. RESULTS: Treatment with recombinant human tumor necrosis factor-related apoptosis-inducing ligand produced greater inhibitory effects in the hyperthermia group than in the control group. Moreover, death receptor protein expression in the hyperthermia group was upregulated on the cell surface (and overall), although death receptor mRNA was downregulated. The half-life of death receptor was several hours longer in the hyperthermia group; concomitantly, E3 ubiquitin ligase expression and death receptor ubiquitination were downregulated in this group. CONCLUSION: Our findings suggested that hyperthermia enhances apoptotic signaling by tumor necrosis factor-related apoptosis-inducing ligand via the suppression of death receptor ubiquitination, which upregulates death receptor expression. These data suggest that the combination of hyperthermia and tumor necrosis factor-related apoptosis-inducing ligand has implications in developing a novel treatment strategy for oral squamous cell carcinoma.

Xylosyl Extension of O-Glucose Glycans on the Extracellular Domain of NOTCH1 and NOTCH2 Regulates Notch Cell Surface Trafficking.

Biochemical and genetic studies have indicated that O-linked glycosylation such as O-glucose (Glc), fucose (Fuc), and N-acetylglucosamine (GlcNAc) is critical for Notch signaling; however, it is not fully understood how O-glycans regulate the Notch receptor function. Notch receptors are type-I transmembrane proteins with large extracellular domains (ECD), containing 29-36 epidermal growth factor-like (EGF) repeats. Here, we analyzed O-Glc glycans on NOTCH1 and NOTCH2 expressed in HEK293T cells using an Orbitrap Fusion mass spectrometer and successfully revealed the structures and stoichiometries of all 17 EGF repeats of NOTCH1 with the O-Glc consensus sequence (C1-X-S-X-(P/A)-C2), and 16 out of 17 EGF repeats of NOTCH2 with the same consensus sequence. High levels of O-Glc attachment and xylosyl elongation were detected on most NOTCH1 and NOTCH2 EGF repeats. When both glucoside xylosyltransferases, GXYLT1 and GXYLT2, responsible for the xylosyl elongation of O-glucose, were genetically deleted, the expression of endogenous NOTCH1 and NOTCH2 on the surface of HEK293T cells did not change, but the cell surface expression of overexpressed NOTCH1 and NOTCH2 decreased compared with that in the wild type cells. In vitro secretion assays consistently showed a reduced secretion of both the NOTCH1 and NOTCH2 ECDs in GXYLT1 and GXYLT2 double knockout cells compared with the wild type cells, suggesting a significant role of the elongation of O-Glc glycans on the Notch ECDs in the quality control of Notch receptors.

Effects of Notch glycosylation on health and diseases.

Notch signaling is an evolutionarily conserved signaling pathway and is essential for cell-fate specification in metazoans. Dysregulation of Notch signaling results in various human diseases, including cardiovascular defects and cancer. In 2000, Fringe, a known regulator of Notch signaling, was discovered as a Notch-modifying glycosyltransferase. Since then, glycosylation-a post-translational modification involving literal sugars-on the Notch extracellular domain has been noted as a critical mechanism for the regulation of Notch signaling. Additionally, the presence of diverse O-glycans decorating Notch receptors has been revealed in the extracellular domain epidermal growth factor-like (EGF) repeats. Here, we concisely summarize the recent studies in the human diseases associated with aberrant Notch glycosylation.

Distribution of TRPVs, P2X3, and parvalbumin in the human nodose ganglion.

Immunohistochemistry for several neurochemical substances, the transient receptor potential cation channel subfamily V member 1 (TRPV1) and 2 (TRPV2), P2X3 receptor, and parvalbumin (PV), was performed on the nodose ganglion, pharynx, and epiglottis in human cadavers. The nodose ganglion was situated beneath the jugular foramen, and had a spindle shape with the long rostrocaudal axis. The pharyngeal branch (PB) issued from a rostral quarter of the nodose ganglion, whereas the superior laryngeal nerve (SLN) usually originated from a caudal half of the ganglion. In the nodose ganglion, sensory neurons were mostly immunoreactive for TRPV1 (89 %) or P2X3 (93.9 %). About 30 % of nodose neurons contained TRPV2 (35.7 %)-or PV (29.9 %)-immunoreactivity (-IR). These neurons mainly had small to medium-sized cell bodies, and were distributed throughout the ganglion. Neurodegenerative profiles such as shrinkage or pyknosis could not be detected in the examined ganglion. Occasionally, TRPV2-IR nerve fibers surrounded blood vessels in the epiglottis as well as in the nasal and oral parts of the pharynx. Isolated TRPV2-IR nerve fibers were also located beneath the epithelium. TRPV1-, P2X3-, or PV-IR nerve endings could not be detected in the pharynx or epiglottis. In the PB and SLN, however, numerous nerve fibers contained TRPV1-, TRPV2-, P2X3-, and PV-IR. The present study suggests that TRPV1-, TRPV2-, P2X3-, and PV-IR neurons in the human nodose ganglion innervate the pharynx and epiglottis through the PB and SLN. These neurons may respond to chemical, thermal, and mechanical stimuli during respiration and swallowing.