Stromal carcinoma-related fibroblasts (CAFs) are the main type of non-immune cells in the tumor microenvironment (TME). CAFs interact with cancer cells to promote tumor proliferation. Long non-coding RNAs (lncRNAs) are known to regulate cell growth, apoptosis and metastasis of cancer cells, but their role in stromal cells is unclear. Using RNA sequencing, we identified a stromal lncRNA signature during the transformation of CAFs from normal fibroblasts (NFs) in oral squamous cell carcinoma (OSCC). We uncovered an uncharacterized lncRNA, FLJ22447, which was remarkably up-regulated in CAFs, referred to LncRNA-CAF (Lnc-CAF) hereafter. Interleukin-33 (IL-33) was mainly located in the stroma and positively co-expressed with Lnc-CAF to elevate the expression of CAF markers (α-SMA, vimentin and N-cadherin) in fibroblasts. In a co-culture system, IL-33 knockdown impaired Lnc-CAF-mediated stromal fibroblast activation, leading to decreased proliferation of tumor cells. Mechanistically, Lnc-CAF up-regulated IL-33 levels and prevented p62-dependent autophagy-lysosome degradation of IL-33, which was independent of LncRNA-protein scaffold effects. Treatment with the autophagy inducer, rapamycin, impaired the proliferative effect of Lnc-CAF/IL-33 by promoting IL-33 degradation. In turn, tumor cells further increased Lnc-CAF levels in stromal fibroblasts via exosomal Lnc-CAF. In patients with OSCC, high Lnc-CAF/IL-33 expression correlated with high TNM stage (n = 140). Moreover, high Lnc-CAF expression predicted poor prognosis. In vivo, Lnc-CAF knockdown restricted tumor growth and was associated with decreased Ki-67 expression and α-SMA+ CAF in the stroma. In conclusion, we identified a stromal lncRNA signature, which reprograms NFs to CAFs via Lnc-CAF/IL-33 and promotes OSCC development.

Saliva is a noninvasive biofluid that can contain metabolite signatures of oral squamous cell carcinoma (OSCC). Conductive polymer spray ionization mass spectrometry (CPSI-MS) is employed to record a wide range of metabolite species within a few seconds, making this technique appealing as a point-of-care method for the early detection of OSCC. Saliva samples from 373 volunteers, 124 who are healthy, 124 who have premalignant lesions, and 125 who are OSCC patients, were collected for discovering and validating dysregulated metabolites and determining altered metabolic pathways. Metabolite markers were reconfirmed at the primary tissue level by desorption electrospray ionization MS imaging (DESI-MSI), demonstrating the reliability of diagnoses based on saliva metabolomics. With the aid of machine learning (ML), OSCC and premalignant lesions can be distinguished from the normal physical condition in real time with an accuracy of 86.7%, on a person by person basis. These results suggest that the combination of CPSI-MS and ML is a feasible tool for accurate, automated diagnosis of OSCC in clinical practice.

The negative role of the activated stimulator of IFN genes (STING) has been uncovered in autoinflammatory disease and cancer. However, the role of STING in virus-related carcinogenesis is not well known. Herein, HPV(+) tongue squamous cell carcinoma (TSCC) (n=25) and HPV(-) TSCC samples (n=25) were randomly collected and were verified by in situ hybridization (ISH) and p16 immunohistochemistry (IHC) to assess the expression and activated status of STING through IHC. The results showed that the expression of STING was up-regulated during the development of TSCC. Interestingly, although the expression of STING showed no difference between HPV(+/-) TSCC samples, the activated status of STING with dark staining around the nucleus was observed in HPV(+) TSCC samples. The role of activated STING was analyzed in three cell lines by siRNA and indicated that activated STING had no impact on cell viability or apoptosis but promoted the induction of several immunosuppressive cytokines, e.g., IL-10, IDO and CCL22, which facilitated the infiltration of regulatory T cells (Tregs). Moreover, increased infiltration of Foxp3(+) Tregs along with increased expression of CCL22 was confirmed in HPV(+) TSCC samples. An inhibitor of the MAPK/AP-1 pathway (U0126) and the silencing of c-jun significantly suppressed CCL22 induction and the recruitment of Tregs by activated STING. Furthermore, down-regulated miR-27 was verified in independent fresh TSCC samples (n=50) and eight cell lines, which enhanced STING activation and led to increased CCL22 expression for Tregs recruitment in the TSCC microenvironment. Therefore, our findings provided distinct insight into the side effects of activated STING in HPV-related carcinogenesis.

Routine mode CBCT imaging was clinically useful for detection of two canals and determines the position of root canal bifurcations in mandibular incisors.