IL-33/ST2 signaling promotes constitutive and inductive PD-L1 expression and immune escape in oral squamous cell carcinoma.

BACKGROUND: Loss-of-function of PD-L1 induces therapy resistance of anti-PD-1/L1 therapy, and the complex regulatory mechanisms are not completely understood. We previously reported that stroma-derived interleukin-33 (IL-33) promoted the progression of oral squamous cell carcinoma (OSCC). We here focused on the immune-regulation role of IL-33 and its receptor ST2 signaling in PD-L1-positive OSCC patients. METHODS: Activated T cells in in situ and peripheral blood were analyzed by IL-33/ST3 expression. Knockdown or overexpression of ST2 combined with IL-33/IFN-γ stimulation were performed to determine PD-L1 expression and PD-L1-dependent immune escape in OSCC/human T cells co-culture system, and OSCC orthotopic model based on humanized mouse with immune reconstitution and C57BL/6 mice models. RESULTS: High IL-33/ST2 correlated with less activated T cells infiltration in situ and peripheral blood. Knockdown of ST2 down-regulated constitutive PD-L1 expression, whereas ST2 also promoted IL-33-induced PD-L1 Mechanistically, IL-33/ST2 activated JAK2/STAT3 pathway to directly promoted PD-L1 expression, and also activated MyD88/NF-κB signaling to up-regulate IFN-γ receptor (IFN-γR), which indirectly strengthen IFN-γ-induced PD-L1. Furthermore, ST2 is required for PD-L1-mediated immune tolerance in vitro and in vivo. ST2high OSCC patients have more PD-L1 and IFN-γR level in situ. CONCLUSIONS: IL-33/ST2 signaling enhanced PD-L1-mediated immune escape, ST2high OSCC patients might benefit from anti-PD-1/L1 therapy.

OXTRHigh stroma fibroblasts control the invasion pattern of oral squamous cell carcinoma via ERK5 signaling.

The Pattern Of Invasion (POI) of tumor cells into adjacent normal tissues clinically predicts postoperative tumor metastasis/recurrence of early oral squamous cell carcinoma (OSCC), but the mechanisms underlying the development of these subtypes remain unclear. Focusing on the highest score of POIs (Worst POI, WPOI) present within each tumor, we observe a disease progression-driven shift of WPOI towards the high-risk type 4/5, associated with a mesenchymal phenotype in advanced OSCC. WPOI 4-5-derived cancer-associated fibroblasts (CAFsWPOI4-5), characterized by high oxytocin receptor expression (OXTRHigh), contribute to local-regional metastasis. OXTRHigh CAFs induce a desmoplastic stroma and CCL26 is required for the invasive phenotype of CCR3+ tumors. Mechanistically, OXTR activates nuclear ERK5 transcription signaling via Gαq and CDC37 to maintain high levels of OXTR and CCL26. ERK5 ablation reprograms the pro-invasive phenotype of OXTRHigh CAFs. Therefore, targeting ERK5 signaling in OXTRHigh CAFs is a potential therapeutic strategy for OSCC patients with WPOI 4-5.

The KiSS-1/GPR54 system: Essential roles in physiological homeostasis and cancer biology.

KiSS-1, first identified as an anti-metastasis gene in melanoma, encodes C-terminally amidated peptide products, including kisspeptin-145, kisspeptin-54, kisspeptin-14, kisspeptin-13 and kisspeptin-10. These products are endogenous ligands coupled to G protein-coupled receptor 54 (GPR54)/hOT7T175/AXOR12. To date, the regulatory activities of the KiSS-1/GPR54 system, such as puberty initiation, antitumor metastasis, fertility in adulthood, hypothalamic-pituitary-gonadal axis (HPG axis) feedback, and trophoblast invasion, have been investigated intensively. Accumulating evidence has demonstrated that KiSS-1 played a key role in reproduction and served as a promising biomarker relative to the diagnosis, identification of therapeutic targets and prognosis in various carcinomas, while few studies have systematically summarized its subjective factors and concluded the functions of KiSS-1/GPR54 signaling in physiology homeostasis and cancer biology. In this review, we retrospectively summarized the regulators of the KiSS-1/GPR54 system in different animal models and reviewed its functions according to physiological homeostasis regulations and above all, cancer biology, which provided us with a profound understanding of applying the KiSS-1/GPR54 system into medical applications.

Worst Pattern of Perineural Invasion Redefines the Spatial Localization of Nerves in Oral Squamous Cell Carcinoma.

As a key histopathological characteristic of tumor invasion, perineural invasion (PNI) assists tumor dissemination, whereas the current definition of PNI by dichotomy is not accurate and the prognostic value of PNI has not reached consensus. To define PNI status in each patient when mixed types of PNI occurred simultaneously, we here further subclassified the traditional PNI in 183 patients with oral squamous cell carcinoma (OSCC). The spatial localization of nerves in OSCC microenvironment was thoroughly evaluated and successfully concluded into four types of PNI: 0, tumor cells away from nerves; 1, tumor cells encircling nerves less than 33%; 2, tumor cells encircling nerves at least 33%; and 3, tumor cells infiltrating into nerve sheathes. Sequentially, patients were stratified by single and mixed types of PNI. Traditionally, types 0 and 1 were defined as PNI-, while types 2 and 3 were PNI+, which predicted shorter survival time. When multiple types of PNI existed within one tumor, patients with higher score of PNI types tended to have a relatively worse prognosis. Therefore, to define the status of PNI more precisely, the new variable worst pattern of PNI (WPNI) was proposed, which was taken as the highest score of PNI types present in each patient no matter how focal. Results showed that patients with WPNI 1 had longest survival time, and WPNI 2 correlated with better overall survival (p = 0.02), local-regional recurrence-free survival (p = 0.03), and distant metastasis-free survival (p = 0.046) than WPNI 3. Multivariate Cox analysis confirmed that only WPNI 3 could independently predict patients' prognosis, which could be explained by a more damaged immune response in WPNI 3 patients with less CD3+CD8+ T cells and CD19+ B cells. Conclusively, WPNI by trichotomy provide more meticulous and precise pathological information for tumor-nerve interactions in OSCC patients.

Functional Heterogeneity of Reelin in the Oral Squamous Cell Carcinoma Microenvironment.

BACKGROUND: Reelin, an extracellular glycoprotein, is expressed on neuronal cells and participates in neuronal migration during brain development. Recently, Reelin also has a vital role in carcinogenesis. However, its role in oral squamous cell carcinoma (OSCC) remains to be explored. The purpose of this study was to explore the roles of Reelin in OSCC. METHODS: The expression of Reelin in cancer-associated fibroblasts (ReelinCAF) and tumor cells (ReelinTC) was analyzed by the Gene Expression Omnibus (GEO) database. Immunohistochemistry (IHC) was used to detect the spatial pattern of Reelin in 75 OSCCs. The diagnostic and prognostic values of Reelin were evaluated and also verified by The Cancer Genome Atlas (TCGA) database. Primary CAFs from 13 OSCC patients were isolated to confirm Reelin expression. Thirty-nine OSCC peripheral blood samples were used to analyze the change of immunocytes based on Reelin levels by flow cytometry. The relationship between Reelin and tumor immune microenvironment in head and neck squamous cell carcinoma (HNSCC) tissues was determined by TISIDB and the Tumor Immune Estimation Resource (TIMER) database. RESULTS: In breast cancer, pancreatic cancer and rectal cancer, Reelin in CAFs was significantly upregulated compared with Reelin in TCs. The IHC results in OSCC also showed that Reelin levels were higher in CAFs. Upregulated ReelinTC was related to a decreased pN stage and distant metastasis. Strikingly, patients with enhanced ReelinCAF had a high risk of lymph node metastasis, poor worst pattern of invasion (WPOI), and distant metastasis, but showed comparable Ki-67 level in all OSCC patients, resulting in shorter overall survival (OS) and disease-specific survival (DSS). Unexpectedly, Reelin in tumor-infiltrating lymphocytes (ReelinTIL) was correlated with postoperative relapse. Patients with high ReelinTIL, but not ReelinTC and ReelinCAF, had poor cytotoxicity of CD8+ T cells and higher ratio of CD4/CD8 in peripheral blood. However, Reelin was positively associated with tissue-resident B cells and NK cells in the tumor microenvironment. CONCLUSION: Reelin has a versatile function in distinct cell types during the development of OSCC via governing tumor cell and stroma microenvironment.

CD38 Multi-Functionality in Oral Squamous Cell Carcinoma: Prognostic Implications, Immune Balance, and Immune Checkpoint.

BACKGROUND: CD38 belongs to the ribosyl cyclase family and is expressed on various hematological cells and involved in immunosuppression and tumor promotion. Although targeting CD38 antibodies has been approved for treatment of multiple myeloma, the function of CD38 in solid tumor, oral squamous cell carcinoma (OSCC) etc., has not been investigated. METHODS: This retrospective study included 92 OSCC samples and analyzed the spatial distribution of CD38 by immunohistochemistry (IHC). The values of diagnosis and prognosis of CD38 were evaluated. Additionally, 53 OSCC preoperative peripheral blood samples were used to be analyzed by flow cytometry. Tumor Immune Estimation Resource (TIMER) and cBioPortal databases were used to study CD38 level in various tumors and its correlation with tumor immune microenvironment in head and neck squamous cell carcinoma (HNSCC). RESULTS: CD38 ubiquitously presented in tumor cells (TCs), fibroblast-like cells (FLCs), and tumor-infiltrating lymphocytes (TILs). Patients with highly expressed CD38 in TCs (CD38TCs) had higher TNM stage and risk of lymph node metastasis. Upregulation of CD38 in FLCs (CD38FLCs) was significantly associated with poor WPOI. Escalated CD38 in TILs (CD38TILs) led to higher Ki-67 level of tumor cells. Moreover, patients with enhanced CD38TCs were susceptible to postoperative metastasis occurrence, and those with highly expressed CD38TILs independently predicted shorter overall and disease-free survival. Strikingly, patients with highly expressed CD38TILs, but not CD38TCs and CD38FLCs, had significantly lower CD3+CD4+ T cells and higher ratio of CD3-CD16+CD56+NK cells. The imbalance of immune system is attributed to dysregulated immune checkpoint molecules (VISTA, PD-1, LAG-3, CTLA-4, TIGIT, GITR) as well as particular immune cell subsets, which were positively correlated with CD38 expression in HNSCC. CONCLUSION: CD38 is a poor prognostic biomarker for OSCC patients and plays a vital role in governing immune microenvironment and circulating lymphocyte homeostasis. Co-expression between CD38 and immune checkpoint molecules provides new insight into immune checkpoint therapy.

The balance of serum IL-18/IL-37 levels is disrupted during the development of oral squamous cell carcinoma.

Growing evidences have demonstrated a pivotal role of chronic inflammation in oral squamous cell carcinoma (OSCC) through the modulation of inflammatory cells and cytokine production. IL-37 is newly discovered anti-inflammatory member of IL-1 family and can bind to IL-18 receptor to inhibit IL-18 (pro-inflammatory member of IL-1 family) function. Investigation on the balance of IL-18/IL-37 would provide new insights into the function of IL-1 family in OSCC. Thus, serum IL-18 and IL-37 levels of OSCC patients (n = 108), leukoplakia patients (n = 40), and healthy donors (n = 36) were collected to analyze the balance of IL-18 and IL-37, and also determine their diagnostic value and prognostic significance in OSCC. The results showed that OSCC patients had high IL-18 and low IL-37 levels in serum and peripheral blood mononuclear cell (PBMC). The ratio of IL-18/IL-37 in serum efficiently distinguished non-cancer individuals from OSCC patients (cut off value: 2.15). Moreover, patients with high IL-18 and low IL-37 were susceptible to develop advanced tumor stage and lymph node metastasis (Odd ratios of IL-18/IL-37 is 4.903 and 12.613, respectively). Meanwhile, higher IL-18/IL-37 ratio could predict shorter overall survival and disease-free survival of OSCC patients, although it was not an independent prognostic factor. We further analyze the correlations of serum IL-18/IL-37 with immunocytes in peripheral blood and found that high IL-18 level was associated with more CD19+ B cells, while serum IL-37 seem to be associated with reduced percentage of CD3+CD8+ T cells, indicating its balance could change the adaptive immune response. Unexpectedly, we first revealed the different function of IL-18/IL-37 in serum and tumor tissues. High mRNA expression of IL-18 in tumor tissues correlated with low lymph node metastasis rate and low tumor stage, which was contradictory to the pro-tumor role of IL-18 in serum. In conclusion, enhanced ratio of IL-18/IL-37 level in serum could be an efficient biomarker for OSCC. Its balance might regulate CD19+ B cells and CD3+ CD8+ T cells for OSCC progression.

Clear Cell Odontogenic Carcinoma: a Clinicopathological and Immunocytochemical Analysis.

Clear cell odontogenic carcinoma (CCOC) is a rare odontogenic tumor associated with aggressive clinical behavior, metastasis and low survival. To date, only 67 cases have been described in the English language literature, and an understanding of the behavior of CCOC has been based on limited case reports. The aim of the research was to further reveal the features of CCOC. We report 5 new cases of CCOC, with a mean age of 52.4 years. The clinical and histopathologic data of the disease obtained from earlier literature (95 cases) and the 5 new cases were analyzed. Data were extracted, including demographics, histopathologic findings, clinical presentation, primary treatment and outcomes. Immunohistochemical results revealed that the cancer is positive for AE1/AE3, EMA and CK19, negative for smooth muscle actin SMA, Vim and S-100. EWSR1 translocation was also observed in the new cases, which may help in the diagnosis of CCOC. Metastases of CCOC were rare, but the local recurrence rate of CCOC rose to 42%. The best treatment for patients with CCOC is wide local excision combined with regional lymph node dissection.

Tumor-infiltrating lymphocyte-derived MLL2 independently predicts disease-free survival for patients with early-stage oral squamous cell carcinoma.

BACKGROUND: MLL2 (mixed-lineage leukemia 2) is recognized as an essential role in regulating histone 3 lysine 4 tri-methylation (H3K4me3) in mammalian cells. It is frequently mutated to promote developmental diseases and tumor initiation. However, the expression pattern of MLL2 and its clinical significance for patients with early-stage oral squamous cell carcinoma (OSCC) remain totally unknown. METHODS: Eighty-five samples of primary early-stage OSCC were enrolled in this retrospective study, and immunohistochemistry (IHC) was performed to detect the spatial pattern of MLL2. The diagnostic and prognostic value of MLL2 were assessed. RESULTS: MLL2 was widely expressed in tumor cells (TCs), fibroblast-like cells (FLCs), and tumor-infiltrating lymphocytes (TILs), both in tumor center and invasive tumor front, and showed no distributive heterogeneity. Moreover, regardless of cell types and microlocalization, patients with high expressed MLL2 had increased depth invasion of tumor (DOI). Besides, upregulation of MLL2TC and MLL2TIL in tumor center were both associated with poor differentiation, but showed no correlation with tumor growth with comparable Ki-67 levels. Prognostic analysis indicated that early-stage OSCC patients with enhanced MLL2TIL in invasive tumor front were susceptible to occur postoperative metastasis and recurrence. Indeed, patients with higher expressed MLL2TIL showed shorter overall survival (OS) and disease-free survival (DFS), and MLL2TIL in invasive tumor front was an independent risk factor of DFS. CONCLUSION: TIL-derived MLL2 in invasive tumor front was an independent prognostic factor of DFS for early-stage OSCC patients.

Aberrant Expression Of PDCD4/eIF4A1 Signal Predicts Postoperative Recurrence For Early-Stage Oral Squamous Cell Carcinoma.

BACKGROUND: Programmed cell death 4 (PDCD4) as a tumor suppressor gene inhibits growth and metastasis of cancer cells, which involved with eIF4A1, the inhibitor of translation initiation. Although the prognosis of early-stage oral squamous cell carcinoma (OSCC) is generally better, but many patients occur recurrence after surgery. Understanding the clinical expression pattern of PDCD4/eIF4A1 signal would provide diagnostic biomarker and target therapy premise for early-stage OSCC patients. METHODS: Immunohistochemical analysis was performed on 69 early-stage (T1/2N0M0) OSCC samples to evaluate temporal expression and prognostic value of eIF4A1 and PDCD4 in early-stage OSCC according to cell types and microlocalization. The correlations between PDCD4/eIF4A1 signal and Ki-67, postoperative recurrence and metastasis were determined. RESULTS: We found that PDCD4 was presented in tumor cells (TCs) and tumor-infiltrating lymphocytes (TILs) but absent in fibroblast-like cells (FLCs). eIF4A1 was only presented in TCs. PDCD4TCs was negative associated with eIF4A1TCs in tumor center, and patients with low PDCD4TCs or high eIF4A1TCs had poorer differentiation. Moreover, aberrant PDCD4/eIF4A1 signal led to higher Ki-67 level. Interestingly, patients with low expressed PDCD4TILs had better prognosis, indicating the function heterogeneity of PDCD4 in different cell types. Furthermore, low PDCD4 TCs and high eIF4A1TCs predicted higher postoperative recurrence rate and are significant independent risk factors for early-stage OSCC. CONCLUSION: Patients with low PDCD4TCs and high eIF4A1TCs have higher recurrence rate and poor clinical outcome. Of note, PDCD4TILs exerts contradictory function. Thus, PDCD4/eIF4A1 targeting therapeutics should consider the function heterogeneity of PDCD4.

The Regulatory Role of Non-coding RNAs on Programmed Cell Death Four in Inflammation and Cancer.

Programmed cell death 4 (PDCD4) is a tumor suppressor gene implicated in many cellular functions, including transcription, translation, apoptosis, and the modulation of different signal transduction pathways. The downstream mechanisms of PDCD4 have been well-discussed, but its upstream regulators have not been systematically summarized. Noncoding RNAs (ncRNAs) are gene transcripts with no protein-coding potential but play a pivotal role in the regulation of the pathogenesis of solid tumors, cardiac injury, and inflamed tissue. In recent studies, many ncRNAs, especially microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), were found to interact with PDCD4 to manipulate its expression through transcriptional regulation and function as oncogenes or tumor suppressors. For example, miR-21, as a classic oncogene, was identified as the key regulator of PDCD4 by targeting its 3'-untranslated region (UTR) to promote tumor proliferation, migration, and invasion in colon, breast, and bladder carcinoma. Therefore, we reviewed the recently emerging pleiotropic regulation of PDCD4 by ncRNAs in cancer and inflammatory disorders and aimed to shed light on the mechanisms of associated diseases, which could be conducive to the development of novel treatment strategies for PDCD4-induced diseases.