Decreased Sirtuin 4 Levels Promote Cellular Proliferation and Invasion in Papillary Thyroid Carcinoma.

OBJECTIVE: This study examined the effect of Sirtuin 4 (Sirt4), a NAD+-dependent deacetylase, on the proliferation and progression of papillary thyroid carcinoma (PTC). METHODS: Data from The Cancer Genome Atlas (TCGA) were analyzed to identify Sirt4 expression in thyroid cancer. Subsequently, the correlation between Sirt4 expression and clinical characteristics was examined in 205 PTC tissue samples. In vitro assays using three human thyroid cancer cell lines (B-CPAP, TPC-1, and SNU-790) were conducted to assess the effects of regulated Sirt4 expression on cell growth, apoptosis, invasion, and migration. Furthermore, in vivo experiments were performed in a xenograft mouse model. RESULTS: GEO and TCGA data indicated that Sirt4 expression is lower in thyroid cancer and Sirt4 downregulation is associated with poor overall survival. In our PTC tissues, positive Sirt4 expression was associated with decreased extracapsular extension. In in vitro experiments using three human thyroid cancer cell lines, overexpression of Sirt4 decreased cell survival, clonogenic potential, and invasion and migratory capabilities, as well as inducing apoptosis and increasing reactive oxygen species levels. Sirt4 overexpression upregulated E-cadherin and downregulated N-cadherin, suggesting its potential involvement in the regulation of epithelial-mesenchymal transition. These findings were confirmed in vivo using a xenograft mouse model. CONCLUSION: This study provides novel insight into the potential contribution of Sirt4 to regulation of the pathological progression of PTC. The data suggest that Sirt4 plays a tumor-suppressive role in PTC by inhibiting growth, survival, and invasive potential. Future research should investigate the molecular mechanisms underlying these effects of Sirt4.

Sirt6-Mediated Cell Death Associated with Sirt1 Suppression in Gastric Cancer.

BACKGROUND: Gastric cancer, one of the leading causes of cancer-related death, is strongly associated with H. pylori infection, although other risk factors have been identified. The sirtuin (Sirt) family is involved in the tumorigenesis of gastric cancer, and sirtuins can have pro- or anti-tumorigenic effects. METHODS: After determining the overall survival rate of gastric cancer patients with or without Sirt6 expression, the effect of Sirt6 upregulation was also tested using a xenograft mouse model. The regulation of Sirt6 and Sirt1, leading to the induction of mouse double minute 2 homolog (MDM2) and reactive oxygen species (ROS), was mainly analyzed using Western blotting and immunofluorescence staining, and gastric cancer cell (SNU-638) death associated with these proteins was measured using flow cytometric analysis. RESULTS: Sirt6 overexpression led to Sirt1 suppression in gastric cancer cells, resulting in a higher level of gastric cancer cell death in vitro and a reduced tumor volume. ROS and MDM2 expression levels were upregulated by Sirt6 overexpression and/or Sirt1 suppression according to Western blot analysis. The upregulated ROS ultimately led to gastric cancer cell death as determined via Western blot and flow cytometric analysis. CONCLUSION: We found that the upregulation of Sirt6 suppressed Sirt1, and Sirt6- and Sirt1-induced gastric cancer cell death was mediated by ROS production. These findings highlight the potential of Sirt6 and Sirt1 as therapeutic targets for treating gastric cancer.

Prolonged Positional Downbeat Nystagmus in Benign Paroxysmal Positional Vertigo: A Case Report and Literature Review.

Purpose This study aimed to report an unusual case of benign paroxysmal positional vertigo (BPPV), who showed prolonged positional downbeat nystagmus without latency and was diagnosed with cupulolithiasis of the anterior canal (AC). We compared this case with one of typical AC-BPPV, and possible mechanisms underlying the atypical characteristics were discussed. Method Two patients diagnosed with AC-BPPV were reported. Positional testing using video-oculography goggles was performed, and outcomes were measured via medical records and analysis of videos of the nystagmus. Results Downbeat nystagmus was observed in the contralateral Dix-Hallpike test in both cases. The torsional component was subtle or absent, but motion was induced toward the affected ear. The two cases differed in latency and duration of vertigo, as well as habituation. The patient with atypical nystagmus showed little or no latency and longer duration. Moreover, there was no habituation on repeated tests. The nystagmus showed several differences from that of typical AC-BPPV. Conclusions Based on our case, AC-BPPV may induce various unusual clinical manifestations of nystagmus. Accurate diagnosis requires careful consideration of the patient's symptoms and the characteristics of the nystagmus. Supplemental Material https://doi.org/10.23641/asha.14265356.

IgG4-related disease presenting as otogenic skull base osteomyelitis.

IgG4-related disease (IgG4-RD) is an emerging clinical disease entity characterized by tumefactive lesions at multiple sites with a dense lymphoplasmacytic infiltrate rich in IgG4+ plasma cells. Although almost any organ can be affected, IgG4-RD is most likely to involve the submandibular, lacrimal, or parotid glands in the head and neck region. However, skull base involvement presenting as otogenic skull base osteomyelitis (SBO) is rare. We encountered a 70-year-old male with IgG4-RD presenting primarily with severe otalgia and otorrhea. He had uncontrolled diabetes mellitus and showed clinical manifestations of otogenic SBO. Tissue immunostaining revealed typical features of increased IgG4-positive plasma cells, and hematological examination showed elevated serum IgG4 concentrations. Treatment with corticosteroids significantly improved well-being and partially resolved the lesion based on computed tomography (CT) scan.

Pseudo-spontaneous nystagmus in lateral semicircular canal benign paroxysmal positional vertigo: Correlation with bow and lean test in a pitch plane.

OBJECTIVES: We investigated the incidence and characteristics of pseudo-spontaneous nystagmus (PSN) in benign paroxysmal positional vertigo involving the lateral semicircular canal (LC-BPPV) and evaluated the correlation between PSN and the bow and lean test. METHODS: We examined nystagmus in the sitting position using video-oculography goggles in 131 LC-BPPV patients. The positioning test and bow and lean test were also performed. Patients were divided into canalolithiasis and cupulolithiasis groups according to the character of nystagmus. In each group, the incidence and direction of PSN, correlation with the bow and lean test, and treatment outcome were analyzed. RESULTS: PSN was observed in 25 cases (19.1%) in LC-BPPV patients, 7 of which were canalolithiasis and 18 of which were cupulolithiasis (p = 0.098). Of the 25 patients with PSN, 21 (84%) exhibited nystagmus consistent with the lean test whereas 4 (16%) exhibited nystagmus consistent with the bow test. In patients with PSN, nystagmus was observed in the bow and lean test in all cases (23/23), but in patients without PSN, no nystagmus was observed in 13 cases (13/87) in the bow and lean test (p = 0.048). The number of barbecue maneuvers performed until the end of treatment was 1.4 ± 0.7 in patients with PSN and 1.4 ± 0.9 in those without PSN (p = 0.976). CONCLUSION: We identified PSN in patients with LC-BPPV irrelevant of subtype. Moreover, all patients with PSN showed nystagmus in the bow and lean test. The direction of PSN was mostly consistent with that of the lean test (21/25, 84%). The presence of PSN was not related to the treatment outcome in this study.