Transglutaminase 3 regulates cutaneous squamous carcinoma differentiation and inhibits progression via PI3K-AKT signaling pathway-mediated Keratin 14 degradation.

Cutaneous squamous carcinoma is the second most common epithelial malignancy, associated with significant morbidity, mortality, and economic burden. However, the mechanisms underlying cSCC remain poorly understood. In this study, we identified TGM3 as a novel cSCC tumor suppressor that acts via the PI3K-AKT axis. RT-qPCR, IHC and western blotting were employed to assess TGM3 levels. TGM3-overexpression/knockdown cSCC cell lines were utilized to detect TGM3's impact on epithelial differentiation as well as tumor cell proliferation, migration, and invasion in vitro. Additionally, subcutaneous xenograft tumor models were employed to examine the effect of TGM3 knockdown on tumor growth in vivo. Finally, molecular and biochemical approaches were employed to gain insight into the tumor-suppressing mechanisms of TGM3. TGM3 expression was increased in well-differentiated cSCC tumors, whereas it was decreased in poor-differentiated cSCC tumors. Loss of TGM3 is associated with poor differentiation and a high recurrence rate in patients with cSCC. TGM3 exhibited tumor-suppressing activity by regulating cell proliferation, migration, and invasion both in vitro and in vivo. As a novel cSCC tumor differentiation marker, TGM3 expression was positively correlated with cell differentiation. In addition, our results demonstrated an interaction between TGM3 and KRT14 that aids in the degradation of KRT14. TGM3 deficiency disrupts keratinocytes differentiation, and ultimately leads to tumorigenesis. Furthermore, RNA-sequence analysis revealed that loss of TGM3 enhanced EMT via the PI3K-AKT signaling pathway. Deguelin, a PI3K-AKT inhibitor, blocked cSCC tumor growth induced by TGM3 knockdown in vivo. Taken together, TGM3 inhibits cSCC tumor growth via PI3K-AKT signaling, which could also serve as a tumor differentiation marker and a potential therapeutic target for cSCC. Proposed model depicted the mechanism by which TGM3 suppress cSCC development. TGM3 reduces the phosphorylation level of AKT and degrades KRT14. In the epithelial cell layer, TGM3 exhibits a characteristic pattern of increasing expression from bottom to top, while KRT14 and pAKT are the opposite. Loss of TGM3 leads to reduced degradation of KRT14 and activation of pAKT, disrupting keratinocyte differentiation, and eventually resulting in the occurrence of low-differentiated cSCC.

Successful Treatment of SAM Syndrome With Secukinumab Monotherapy: A Case Report of a 16-Month-Old Infant.

Severe dermatitis, multiple allergies, and metabolic wasting (SAM) syndrome is a rare congenital skin disease. We report on a 16-month-old infant presenting with severe disseminated dermatitis, characterized by erythema and lichenified plaques. The crucial result of de novo missense mutation in the DSP gene (c.1769T>C, p.F590S) discovered by next-generation sequencing finally confirmed the diagnosis of SAM syndrome. The eruptions and skin pruritus significantly improved after a 4-week treatment with secukinumab.

Validation of diagnostic criteria for atopic dermatitis and proposal of novel diagnostic criteria for adult and elderly Chinese populations: a multicentre, prospective, clinical setting-based study.

BACKGROUND: A previous validation study showed a very low sensitivity and higher specificity associated with Hanifin and Rajka criteria (H&R) and the UK Working Party criteria (UKWP) in diagnosing AD vs. the Chinese criteria of atopic dermatitis (AD) for children (CCAD). However, their diagnostic efficacy in adult and elderly Chinese populations remains unknown. OBJECTIVES: To validate the diagnostic efficacy of three sets of AD criteria in adult and elderly Chinese populations in a hospital setting. METHODS: A total of 1034 patients (aged 19-95 years) from five university hospital dermatological clinics were recruited. Medical history, dermatological examination, AD diagnosis and evaluation of AD severity were done by dermatologists. Each patient was investigated by two dermatologist panels, one to establish a clinical diagnosis, and the other to identify and record the major or minor signs of H&R criteria, UKWP criteria and CCAD. Taking clinical diagnosis as the reference, the diagnostic efficacy of three sets of diagnostic criteria was evaluated. The χ2 test or rank sum test were used for between-groups comparisons. RESULTS: CCAD had a higher sensitivity (84.0%), especially among mild and moderate cases of AD (72.7% and 90.3%, respectively), than the H&R (58.0%; P < 0.001) and UKWP criteria (56.0%; P < 0.001) in diagnosing AD. The specificity of CCAD (92.7%) was slightly lower than the H&R (97.3%; P < 0.001) or UKWP criteria (97.4%; P < 0.001). The CCAD had the highest Youden index (0.77), accuracy rate (0.90) and Kappa value (0.76) of the three sets of diagnostic criteria. CONCLUSIONS: Consistent with results in a population of Chinese children, although the H&R and UKWP criteria had a high specificity for diagnosing AD, their low sensitivity limited their use in adult and elderly Chinese patients. Based on the high sensitivity and favourable diagnostic efficacy, the CCAD is proposed for AD diagnosis in adult and elderly Chinese populations, especially for cases of mild and moderate AD.

Themis2 lowers the threshold for B cell activation during positive selection.

The positive and negative selection of lymphocytes by antigen is central to adaptive immunity and self-tolerance, yet how this is determined by different antigens is not completely understood. We found that thymocyte-selection-associated family member 2 (Themis2) increased the positive selection of B1 cells and germinal center B cells by self and foreign antigens. Themis2 lowered the threshold for B-cell activation by low-avidity, but not high-avidity, antigens. Themis2 constitutively bound the adaptor protein Grb2, src-kinase Lyn and signal transducer phospholipase γ2 (PLC-γ2), and increased activation of PLC-γ2 and its downstream pathways following B cell receptor stimulation. Our findings identify a unique function for Themis2 in differential signaling and provide insight into how B cells discriminate between antigens of different quantity and quality.