Immature myeloid cells such as myeloid-derived suppressor cells (MDSCs) and M2 macrophages play a vital role in the tumor immune escape and tumor progression. Cytotoxic T lymphocyte-associated antigen 4 (CTLA4), as a negative immune checkpoint, is highly expressed in numerous solid tumors. However, precise functions of CTLA4 in head and neck squamous cell carcinoma (HNSCC) have not yet been elucidated. In this study, we demonstrated that the ratio of CD8⁺/CTLA4 can be used as a potential index with a clinical prognostic value for HNSCC. Using immunocompetent transgenic mouse model with spontaneous HNSCC, we directly observed that targeting CTLA4 decreases MDSCs and M2 macrophages and promotes T cell activation in both tumor microenvironment and macro-environment. In all, our study provides direct evidence in vivo and proposes a rationale for CTLA4 inhibition as a future therapeutic strategy in patients with HNSCC.

Recent studies showed that incomplete cell reprogramming can transform cells into tumour-like cells. Lin28A is associated with fibroblast and sarcoma cell reprogramming, whereas its homologue Lin28B is associated with hematopoietic cell reprogramming. This study aimed to investigate the expression and prognostic difference between Lin28A and Lin28B in oral squamous cell carcinoma (OSCC). Expression level was assessed by immunohistochemistry and staining location was confirmed by immunofluorescence. Prognostic values were analysed and compared by the Kaplan–Meier analysis and uni and multivariate Cox regression models. Besides, in vitro cell assays and in vivo nude mice xenograft were used to demonstrate the influence of increased Lin28B expression in OSCC. Lin28A and Lin28B expression increased in OSCC, and co-expression of Lin28A and Lin28B showed no significant association with patient prognosis. Kaplan–Meier analysis showed that patients with high Lin28B but not Lin28A expression had lower overall survival (OS) rates than those with low Lin28B expression. Further Univariate analysis showed that patients with increased Lin28B expression had shorter disease-free survival (DFS) and shorter OS, while multivariate analysis showed Lin28B overexpression with TNM stage predicted poor prognosis in patients with OSCC. Besides, stable expressing Lin28B in oral cancer cells promoted cell migration, invasion, colony formation, in vivo proliferation and increased the expression of cancer suppressor miRNA let-7 targeted genes IL-6, HMGA2, the EMT markers Snail and Twist, the angiogenesis inducer VEGF, and the apoptosis inhibitor Survivin. These combined results indicate that Lin28B is a novel marker for predicting prognosis in patients with OSCC and may be a therapeutic target.

Dihydromyricetin promotes autophagy and apoptosis through ROS-STAT3 signaling in head and neck squamous cell carcinoma

Objective: One of the major impediments in tissue-engineered oral mucosa (TEOM) is the lack of rete ridge (RR) structures that can weaken the connection between the epidermis and dermis. This study aimed to investigate the native morphology of RRs as well as the expression of extracellular signal-regulated kinase 1/2 (ERK1/2), Ki67, and keratin-19, which are related to cell mechanotransduction, proliferation, and stemness in the oral epidermis, respectively. Methods: RR characteristics, including type, density, length, and width, were analyzed in the masticatory mucosa (Mm) and lining mucosa (Lm) sites of 52 specimens. The expression of ERK1/2, Ki67, and keratin-19 was assessed by immunohistochemistry. ERK1/2 activation by masticatory stimuli was confirmed in vitro by loading pressure onto cultured keratinocytes isolated from the specimens. Results: Three types of RR were found. The RRs in the Mm and Lm differed. The length and percentage of ERK1/2-positive (%ERK1/2+) basal layer cells had a negative correlation (p = 0.004), whereas the length and %Ki67+ basal layer cells had a positive correlation (p = 0.013). The %ERK1/2+ basal layer cells and %keratin-19+ basal layer cells had a negative relationship (p = 0.011). ERK1/2 activation in the oral epithelium was induced by pressure and propagated in cultured keratinocytes. Conclusion: RRs are longer in the Mm, which may result from the topical basal cell proliferation and migration induced by masticatory pressure via ERK1/2 activation. Our findings preliminarily interpret RR histomorphology as influenced by oral masticatory pressure. Results may benefit future studies on RR development and reconstruction in TEOM models to enhance the epidermis-dermis connection.