Microenvironment in Oral Potentially Malignant Disorders: Multi-Dimensional Characteristics and Mechanisms of Carcinogenesis.

Oral potentially malignant disorders (OPMDs) are a group of diseases involving the oral mucosa and that have a risk of carcinogenesis. The microenvironment is closely related to carcinogenesis and cancer progression by regulating the immune response, cell metabolic activities, and mechanical characteristics. Meanwhile, there are extensive interactions between the microenvironments that remodel and provide favorable conditions for cancer initiation. However, the changes, exact roles, and interactions of microenvironments during the carcinogenesis of OPMDs have not been fully elucidated. Here, we present an updated landscape of the microenvironments in OPMDs, emphasizing the changes in the immune microenvironment, metabolic microenvironment, mechanical microenvironment, and neural microenvironment during carcinogenesis and their carcinogenic mechanisms. We then propose an immuno-metabolic-mechanical-neural interaction network to describe their close relationships. Lastly, we summarize the therapeutic strategies for targeting microenvironments, and provide an outlook on future research directions and clinical applications. This review depicts a vivid microenvironment landscape and sheds light on new strategies to prevent the carcinogenesis of OPMDs.

A case of Melkersson-Rosenthal syndrome with endocrine disorders: Extraordinary efficiency of hydroxychloroquine and mechanism hypothesis.

BACKGROUND AND PURPOSE: Melkersson-Rosenthal syndrome (MRS) is a rare neuro-mucocutaneous disease. In addition to the traditional clinical triad, there is also a diversity of clinical signs, and it may be related to other systemic diseases. METHODS: In the present study, we report a case of MRS with endocrine disorders that exhibits extraordinary therapeutic efficiency by using hydroxychloroquine (HCQ), explore whether there is an internal connection between MRS and endocrine disorders, and discuss the mechanism of the therapeutic efficiency of using HCQ. The hypothesis proposed for the first time is that MRS may essentially be a systemic granulomatous disease. RESULTS: The physical examination revealed orofacial swelling and fissured tongue. The histopathologic examination showed epithelioid granulomas. Combined with the other examination, this case was diagnosed as incomplete MRS. HCQ and local drugs were introduced. The patient achieved clinical recovery and psychological cure by the 18-week follow-up, and the 1-year follow-up found no reactivation of MRS. Moreover, the levels of cortisol and adrenocorticotropic were within normal ranges. CONCLUSIONS: After the drug therapy was targeted at granuloma, not only did all of the symptoms related to MRS disappear, but the endocrine system also returned to normal. It is speculated that the endocrine disorder in this patient may be related to MRS. We further propose the first-time hypothesis that MRS may essentially be a systemic granulomatous disease. It provides a new medication method with high-level efficiency.

The efficacy and safety of thalidomide on the recurrence interval of continuous recurrent aphthous ulceration: A randomized controlled clinical trial.

BACKGROUND: Recurrent aphthous ulceration (RAU) is the most common oral mucosal disease. Some patients have almost continuous oral ulcers which influence the quality of life. The aim of this study was to observe the efficacy and safety of thalidomide on the recurrence interval of continuous RAU. METHODS: A randomized controlled clinical trial was designed, and 60 continuous RAU patients were randomly assigned to the experimental group (n = 32, taking thalidomide before bed at a dose of 100 mg/d for 10 days, then 50 mg/d for 10 days, and 25 mg/d for 10 days) and the control group (n = 28, taking 0.4 mg/kg/d prednisone every morning for 15 days and then 0.2 mg/kg/d for 15 days). The clinical outcomes consisted of the primary outcome (recurrence interval) and the secondary outcomes (pain level, number of ulcers, and days for ulcer healing), and they were measured at every visit. Adverse reactions were recorded. RESULTS: A total of 54 and 51 patients presented at the first and second return visit, respectively. After 1 month, the increase in the recurrence interval was not shown to differ between the two groups (P = .12). However, the improvement in the recurrence interval was significantly greater in the experimental group (P < .001) at the second return visit. The improvement in the secondary outcomes was identical between two groups at each return visit (P > .05). The incidence of adverse reactions was similar between two groups (P = .50). CONCLUSIONS: Thalidomide had a long-term effect of extending the recurrence interval of continuous RAU.

A personalized computational model predicts cancer risk level of oral potentially malignant disorders and its web application for promotion of non-invasive screening.

BACKGROUND: Despite their high accuracy to recognize oral potentially malignant disorders (OPMDs) with cancer risk, non-invasive oral assays are poor in discerning whether the risk is high or low. However, it is critical to identify the risk levels, since high-risk patients need active intervention, while low-risk ones simply need to be follow-up. This study aimed at developing a personalized computational model to predict cancer risk level of OPMDs and explore its potential web application in OPMDs screening. METHODS: Each enrolled patient was subjected to the following procedure: personal information collection, non-invasive oral examination, oral tissue biopsy and histopathological analysis, treatment, and follow-up. Patients were randomly divided into a training set (N = 159) and a test set (N = 107). Random forest was used to establish classification models. A baseline model (model-B) and a personalized model (model-P) were created. The former used the non-invasive scores only, while the latter was incremented with appropriate personal features. RESULTS: We compared the respective performance of cancer risk level prediction by model-B, model-P, and clinical experts. Our data suggested that all three have a similar level of specificity around 90%. In contrast, the sensitivity of model-P is beyond 80% and superior to the other two. The improvement of sensitivity by model-P reduced the misclassification of high-risk patients as low-risk ones. We deployed model-P in web.opmd-risk.com, which can be freely and conveniently accessed. CONCLUSION: We have proposed a novel machine-learning model for precise and cost-effective OPMDs screening, which integrates clinical examinations, machine learning, and information technology.

Synergistic Efficacy of Plaque Control with Intralesional Triamcinolone Acetonide Injection on Erosive Non-Gingival Oral Lichen Planus: A Randomized Controlled Clinical Trial.

This study is the first time to assess the synergistic efficacy and safety of plaque control on erosive non-gingival oral lichen planus (OLP). A randomized, controlled, clinical trial with blind evaluation was designed, and 48 OLP patients with erosive non-gingival OLP lesions were randomly assigned to the experimental group (n = 25, receiving intralesional triamcinolone acetonide injection, periodontal scaling, and oral hygiene instruction) and the control group (n = 23, only receiving intralesional triamcinolone acetonide injection) once a week for 2 weeks. Erosion size, pain level, plaque index, and community periodontal index were measured at every visit. Patients cured of erosion were followed up for 3 months to evaluate the recurrence rate. Adverse reactions were also recorded. At day 14 ± 2, the experimental group showed a higher completely healed percentage of erosion, a greater reduction of erosion size and pain level. However, no significant difference was observed in the recurrence rate. No participants had any severe adverse reactions. In conclusion, an improvement was observed in patients with plaque control, and future studies with larger sample sizes are needed to reinforce the external validity of this study.

TGF-ß signaling in the tumor metabolic microenvironment and targeted therapies.

Transforming growth factor-ß (TGF-ß) signaling has a paradoxical role in cancer progression, and it acts as a tumor suppressor in the early stages but a tumor promoter in the late stages of cancer. Once cancer cells are generated, TGF-ß signaling is responsible for the orchestration of the immunosuppressive tumor microenvironment (TME) and supports cancer growth, invasion, metastasis, recurrence, and therapy resistance. These progressive behaviors are driven by an "engine" of the metabolic reprogramming in cancer. Recent studies have revealed that TGF-ß signaling regulates cancer metabolic reprogramming and is a metabolic driver in the tumor metabolic microenvironment (TMME). Intriguingly, TGF-ß ligands act as an "endocrine" cytokine and influence host metabolism. Therefore, having insight into the role of TGF-ß signaling in the TMME is instrumental for acknowledging its wide range of effects and designing new cancer treatment strategies. Herein, we try to illustrate the concise definition of TMME based on the published literature. Then, we review the metabolic reprogramming in the TMME and elaborate on the contribution of TGF-ß to metabolic rewiring at the cellular (intracellular), tissular (intercellular), and organismal (cancer-host) levels. Furthermore, we propose three potential applications of targeting TGF-ß-dependent mechanism reprogramming, paving the way for TGF-ß-related antitumor therapy from the perspective of metabolism.

Glycolysis reprogramming in cancer-associated fibroblasts promotes the growth of oral cancer through the lncRNA H19/miR-675-5p/PFKFB3 signaling pathway.

As an important component of the tumor microenvironment, cancer-associated fibroblasts (CAFs) secrete energy metabolites to supply energy for tumor progression. Abnormal regulation of long noncoding RNAs (lncRNAs) is thought to contribute to glucose metabolism, but the role of lncRNAs in glycolysis in oral CAFs has not been systematically examined. In the present study, by using RNA sequencing and bioinformatics analysis, we analyzed the lncRNA/mRNA profiles of normal fibroblasts (NFs) derived from normal tissues and CAFs derived from patients with oral squamous cell carcinoma (OSCC). LncRNA H19 was identified as a key lncRNA in oral CAFs and was synchronously upregulated in both oral cancer cell lines and CAFs. Using small interfering RNA (siRNA) strategies, we determined that lncRNA H19 knockdown affected proliferation, migration, and glycolysis in oral CAFs. We found that knockdown of lncRNA H19 by siRNA suppressed the MAPK signaling pathway, 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) and miR-675-5p. Furthermore, the lncRNA H19/miR-675-5p/PFKFB3 axis was involved in promoting the glycolysis pathway in oral CAFs, as demonstrated by a luciferase reporter system assay and treatment with a miRNA-specific inhibitor. Our study presents a new way to understand glucose metabolism in oral CAFs, theoretically providing a novel biomarker for OSCC molecular diagnosis and a new target for antitumor therapy.

Cancer-Associated Fibroblasts Facilitate Squamous Cell Carcinoma Lung Metastasis in Mice by Providing TGFß-Mediated Cancer Stem Cell Niche.

Cancer-associated fibroblasts (CAFs) have been shown to enhance squamous cell carcinoma (SCC) growth, but it is unclear whether they promote SCC lung metastasis. We generated CAFs from K15.KrasG12D.Smad4-/- mouse SCCs. RNA expression analyses demonstrated that CAFs had enriched transforming growth factor-beta (TGFß) signaling compared to normal tissue-associated fibroblasts (NAFs), therefore we assessed how TGFß-enriched CAFs impact SCC metastasis. We co-injected SCC cells with CAFs to the skin, tail vein, or the lung to mimic sequential steps of lung metastasis. CAFs increased SCC volume only in lung co-transplantations, characterized with increased proliferation and angiogenesis and decreased apoptosis compared to NAF co-transplanted SCCs. These CAF effects were attenuated by a clinically relevant TGFß receptor inhibitor, suggesting that CAFs facilitated TGFß-dependent SCC cell seeding and survival in the lung. CAFs also increased tumor volume when co-transplanted to the lung with limiting numbers of SCC cancer stem cells (CSCs). In vitro, CSC sphere formation and invasion were increased either with co-cultured CAFs or with CAF conditioned media (which contains the highest TGFß1 concentration) and these CAF effects were blocked by TGFß inhibition. Further, TGFß activation was higher in primary human oral SCCs with lung metastasis than SCCs without lung metastasis. Similarly, TGFß activation was detected in the lungs of mice with micrometastasis. Our data suggest that TGFß-enriched CAFs play a causal role in CSC seeding and expansion in the lung during SCC metastasis, providing a prognostic marker and therapeutic target for SCC lung metastasis.

Transforming Growth Factor-ß Signaling in Fibrotic Diseases and Cancer-Associated Fibroblasts.

Transforming growth factor-ß (TGF-ß) signaling is essential in embryo development and maintaining normal homeostasis. Extensive evidence shows that TGF-ß activation acts on several cell types, including epithelial cells, fibroblasts, and immune cells, to form a pro-fibrotic environment, ultimately leading to fibrotic diseases. TGF-ß is stored in the matrix in a latent form; once activated, it promotes a fibroblast to myofibroblast transition and regulates extracellular matrix (ECM) formation and remodeling in fibrosis. TGF-ß signaling can also promote cancer progression through its effects on the tumor microenvironment. In cancer, TGF-ß contributes to the generation of cancer-associated fibroblasts (CAFs) that have different molecular and cellular properties from activated or fibrotic fibroblasts. CAFs promote tumor progression and chronic tumor fibrosis via TGF-ß signaling. Fibrosis and CAF-mediated cancer progression share several common traits and are closely related. In this review, we consider how TGF-ß promotes fibrosis and CAF-mediated cancer progression. We also discuss recent evidence suggesting TGF-ß inhibition as a defense against fibrotic disorders or CAF-mediated cancer progression to highlight the potential implications of TGF-ß-targeted therapies for fibrosis and cancer.

Regulation of proliferation and cell cycle by protein regulator of cytokinesis 1 in oral squamous cell carcinoma.

Protein regulator of cytokinesis 1 (PRC1), a microtubule-associated protein, has emerged as a critical regulator of proliferation and apoptosis, acting predominantly in numerous tumors. However, its function in oral squamous cell carcinoma (OSCC) is still unknown. To establish the roles of PRC1 in OSCC, 95 oral clinical samples (54 OSCC, 24 oral leukoplakia [OLK], and 17 normal oral mucosa) and seven oral cell lines (6 OSCC and 1 normal oral cell lines) were analyzed using a series of molecular and genomic assays both in vivo and in vitro were conducted in this study. Herein, we provide evidence demonstrating that expression of PRC1 closely correlates with the degree of epithelial dysplasia in OLK (n = 24) (p < 0.001), and the poor differentiation, large tumor volume, lymph node metastasis, and high-clinical stage in OSCC (n = 54) (p < 0.05), illustrating that PRC1 has a promotive influence on tumor progression in OSCC. Simultaneously, we observed that PRC1 knockdown in OSCC cell lines caused G2/M phase arrest (p < 0.05), inhibited cell proliferation in vitro (p < 0.05) and tumor growth in vivo (p < 0.001). Furthermore, the effects of PRC1 on the regulation of proliferation and cell cycle transition in OSCC samples were mediated by p53. The p53/PRC1/EGFR signaling pathway was found to be implicated in the tumor progression of OSCC. Based on our data, we demonstrate that PRC1 is a key factor in regulating proliferation and the cell cycle, pointing to the potential benefits of PRC1-targeted therapies for OSCC.

Extramammary Paget's disease of the oral mucosa and perioral skin.

Extramammary Paget's disease (EMPD) is an unusual intraepidermal adenocarcinoma. Only 2 cases of EMPD in the oral mucosa have been reported previously. Here, we present the first report of a rare case of Paget's disease of the oral mucosa and perioral skin with extensive contiguous erythematous and erosive manifestations. Ultimately, the patient was treated with oral thalidomide for 8 weeks. We noticed an improvement with resolution of symptoms. A 3-year follow-up showed no relapse. Thus, this case may provide new insights to clinicians about treatment of EMPD. More importantly, we advise that dentists be vigilant about the possibility of some clinically significant conditions in patients with extensive nonspecific clinical lesions mimicking inflammatory or infectious diseases in the oral and maxillofacial regions, especially lesions that are refractory to long-term treatment. Requesting consultations with relevant clinical departments promptly and obtaining histopathologic confirmation at an early stage are crucial for early therapy and a better prognosis.

Reduced CX3CL1 Secretion Contributes to the Susceptibility of Oral Leukoplakia-Associated Fibroblasts to Candida albicans.

Candida leukoplakia (OLK) is a kind of oral leukoplakia combined with chronic candidal infection, which plays an important role in the malignant transformation of OLK. However, little is known about the etiology, including susceptibility of leukoplakia to candidal adhesion, invasion and infection. Some antimicrobial peptides secreted by oral epithelial cells or fibroblasts potentially have antifungal activities against Candida albicans (C. albicans). In this study, we established three co-culture models to simulate different C. albicans-fibroblasts interactions during progression of candida leukoplakia. The susceptibility of oral leukoplakia-associated fibroblasts (LKAFs) to C. albicans and its underlying mechanism were determined. Samples of 14 LKAFs and 10 normal fibroblasts (NFs) were collected. The co-culture models showed that LKAFs had promoted the adhesion, invasion, and survival of C. albicans compared with NFs. CX3CL1, a chemokine with antifungal activity, was less abundant in LKAFs than NFs. Overexpression of CX3CL1 via transfection in LKAFs could partly restore the resistance to C. albicans. We also showed that inhibition of ERK could suppress CX3CL1 secretion. While phosphor-ERK was inhibited in LKAFs compared with NFs. Besides, the mRNA expression of a shedding enzyme for CX3CL1, disintegrin and metalloproteinase domain (ADAM) 17 was decreased in LKAFs than NFs. In conclusion, LKAFs produced and secreted less CX3CL1 by inhibiting the ERK signaling pathway, thereby contributing to impaired cell resistance to C. albicans.