PD-1 blockade prevents the progression of oral carcinogenesis

Single-cell transcriptome dissecting the microenvironment remodeled by PD1 blockade combined with photodynamic therapy in a mouse model of oral carcinogenesis

Oral squamous cell carcinoma (OSCC) stands as a predominant and perilous malignant neoplasm globally, with the majority of cases originating from oral potential malignant disorders (OPMDs). Despite this, effective strategies to impede the progression of OPMDs to OSCC remain elusive. In this study, we established mouse models of oral carcinogenesis via 4-nitroquinoline 1-oxide induction, mirroring the sequential transformation from normal oral mucosa to OPMDs, culminating in OSCC development. By intervening during the OPMDs stage, we observed that combining PD1 blockade with photodynamic therapy (PDT) significantly mitigated oral carcinogenesis progression. Single-cell transcriptomic sequencing unveiled microenvironmental dysregulation occurring predominantly from OPMDs to OSCC stages, fostering a tumor-promoting milieu characterized by increased Treg proportion, heightened S100A8 expression, and decreased Fib_Igfbp5 (a specific fibroblast subtype) proportion, among others. Notably, intervening with PD1 blockade and PDT during the OPMDs stage hindered the formation of the tumor-promoting microenvironment, resulting in decreased Treg proportion, reduced S100A8 expression, and increased Fib_Igfbp5 proportion. Moreover, combination therapy elicited a more robust treatment-associated immune response compared with monotherapy. In essence, our findings present a novel strategy for curtailing the progression of oral carcinogenesis.

Genomic Engineering of Oral Keratinocytes to Establish In Vitro Oral Potentially Malignant Disease Models as a Platform for Treatment Investigation

Precancerous cells in the oral cavity may appear as oral potentially malignant disorders, but they may also present as dysplasia without visual manifestation in tumor-adjacent tissue. As it is currently not possible to prevent the malignant transformation of these oral precancers, new treatments are urgently awaited. Here, we generated precancer culture models using a previously established method for the generation of oral keratinocyte cultures and incorporated CRISPR/Cas9 editing. The generated cell lines were used to investigate the efficacy of a set of small molecule inhibitors. Tumor-adjacent mucosa and oral leukoplakia biopsies were cultured and genetically characterized. Mutations were introduced in CDKN2A and TP53 using CRISPR/Cas9 and combined with the ectopic activation of telomerase to generate cell lines with prolonged proliferation. The method was tested in normal oral keratinocytes and tumor-adjacent biopsies and subsequently applied to a large set of oral leukoplakia biopsies. Finally, a subset of the immortalized cell lines was used to assess the efficacy of a set of small molecule inhibitors. Culturing and genomic engineering was highly efficient for normal and tumor-adjacent oral keratinocytes, but success rates in oral leukoplakia were remarkably low. Knock-out of CDKN2A in combination with either the activation of telomerase or knock-out of TP53 seemed a prerequisite for immortalization. Prolonged culturing was accompanied by additional genetic aberrations in these cultures. The generated cell lines were more sensitive than normal keratinocytes to small molecule inhibitors of previously identified targets. In conclusion, while very effective for normal keratinocytes and tumor-adjacent biopsies, the success rate of oral leukoplakia cell culturing methods was very low. Genomic engineering enabled the prolonged culturing of OL-derived keratinocytes but was associated with acquired genetic changes. Further studies are required to assess to what extent the immortalized cultures faithfully represent characteristics of the cells in vivo.

Mass cytometry and transcriptomic profiling reveal PD1 blockade induced alterations in oral carcinogenesis

Oral squamous cell carcinoma is the predominant subtype of head and neck squamous cell carcinoma, characterized by a challenging prognosis. In this study, we established a murine model of oral carcinogenesis using 4-nitroquinoline-1-oxide (4-NQO) induction to investigate the impact of immunotherapy on microenvironmental alterations. Mice in the precancerous condition were randomly divided into two groups: one receiving programmed death-1 (PD1) monoclonal antibody treatment and the other, control immunoglobulin G. Our observations showed that while PD1 blockade effectively delayed the progression of carcinogenesis, it did not completely impede or reverse it. To unravel the underlying reasons for the limited effectiveness of PD1 blockade, we collected tongue lesions and applied mass cytometry (CyTOF) and RNA sequencing (RNA-seq) to characterize the microenvironment. CyTOF analysis revealed an increased macrophage subset (expressing high levels of IFNγ and iNOS) alongside a diminished Th1-like subset (exhibiting low expression of TCF7) and three myeloid-derived suppressor cell subsets (displaying low expression of MHC Class II or IFNγ) following anti-PD1 treatment. Notably, we observed an increased presence of cancer-associated fibroblasts (CAFs) expressing collagen-related genes after PD1 blockade. Furthermore, we found a negative correlation between the infiltration levels of CAFs and CD8+ T cells. These findings were validated in murine tongue tissue slides, and publicly available multi-omics datasets. Our results suggest that CAFs may impair the therapeutic efficacy of PD1 blockade in oral carcinogenesis by the remodeling of the extracellular matrix.

Manganese suppresses the development of oral leukoplakia by activating the immune response

OBJECTIVE

Manganese ion (Mn2+ ) is reported to promote the antitumor immune response by activating the cGAS-STING pathway, but it is unknown whether Mn2+ can prevent the malignant transformation of precancerous lesions. The effects of Mn2+ in treating oral leukoplakia (OLK) were explored in this work.

METHODS

Peripheral blood Mn analysis of the patients was performed using inductively coupled plasma atomic emission spectroscopy (ICP-AES). A coculture model of dendritic cells (DCs)/macrophages, CD8+ T cells, and dysplastic oral keratinocytes (DOKs) was employed to analyze the role and mechanism of Mn2+ in a simulated OLK immune microenvironment. Western blot, RT-PCR, flow cytometry, enzyme-linked immunosorbent assay (ELISA), and lactate dehydrogenase (LDH) assays were adopted to detect the mechanism of Mn2+ in this model. 4-nitroquinoline oxide (4NQO)-induced OLK mice were used to assess the role of Mn2+ in suppressing OLK progression, and a novel Mn2+ -loaded guanosine-tannic acid hydrogel (G-TA@Mn2+ hydrogel) was fabricated and evaluated for its advantages in OLK therapy.

RESULTS

The content of Mn in patients' peripheral blood was negatively related to the progression of OLK. Mn2+ promoted the maturation and antigen presentation of DCs and macrophages and enhanced the activation of CD8+ T cells in the coculture model, resulting in effective killing of DOKs. Mechanistic analysis found that Mn2+ enhanced the anti-OLK immune response by activating the cGAS-STING pathway. Moreover, Mn2+ suppressed the development of 4NQO-induced carcinogenesis in the mouse model. In addition, the G-TA@Mn2+ hydrogel had better anti-OLK effects.

CONCLUSIONS

Mn2+ enhanced the anti-OLK immune response by activating the cGAS-STING pathway, and the G-TA@Mn2+ hydrogel is a potential novel therapeutic approach for OLK treatment.

Targeting anticancer immunity in oral cancer: Drugs, products, and nanoparticles

Oral cavity carcinomas are the most frequent malignancies among head and neck malignancies. Oral tumors include not only oral cancer cells with different potency and stemness but also consist of diverse cells, containing anticancer immune cells, stromal and also immunosuppressive cells that influence the immune system reactions. The infiltrated T and natural killer (NK) cells are the substantial tumor-suppressive immune compartments in the tumor. The infiltration of these cells has substantial impacts on the response of tumors to immunotherapy, chemotherapy, and radiotherapy. Nevertheless, cancer cells, stromal cells, and some other compartments like regulatory T cells (Tregs), macrophages, and myeloid-derived suppressor cells (MDSCs) can repress the immune responses against malignant cells. Boosting anticancer immunity by inducing the immune system or repressing the tumor-promoting cells is one of the intriguing approaches for the eradication of malignant cells such as oral cancers. This review aims to concentrate on the secretions and interactions in the oral tumor immune microenvironment. We review targeting tumor stroma, immune system and immunosuppressive interactions in oral tumors. This review will also focus on therapeutic targets and therapeutic agents such as nanoparticles and products with anti-tumor potency that can boost anticancer immunity in oral tumors. We also explain possible future perspectives including delivery of various cells, natural products and drugs by nanoparticles for boosting anticancer immunity in oral tumors.

Integrative analysis of lysine acetylation-related genes and identification of a novel prognostic model for oral squamous cell carcinoma

Introduction: Oral squamous cell carcinoma (OSCC), which accounts for a high proportion of oral cancers, is characterized by high aggressiveness and rising incidence. Lysine acetylation is associated with cancer pathogenesis. Lysine acetylation-related genes (LARGs) are therapeutic targets and potential prognostic indicators in various tumors, including oral squamous cell carcinoma. However, systematic bioinformatics analysis of the Lysine acetylation-related genes in Oral squamous cell carcinoma is still unexplored. Methods: We analyzed the expression of 33 Lysine acetylation-related genes in oral squamous cell carcinoma and the effects of their somatic mutations on oral squamous cell carcinoma prognosis. Consistent clustering analysis identified two lysine acetylation patterns and the differences between the two patterns were further evaluated. Least absolute shrinkage and selection operator (LASSO) regression analysis was used to develop a lysine acetylation-related prognostic model using TCGA oral squamous cell carcinoma datasets, which was then validated using gene expression omnibus (GEO) dataset GSE41613. Results: Patients with lower risk scores had better prognoses, in both the overall cohort and within the subgroups These patients also had "hot" immune microenvironments and were more sensitive to immunotherapy. Disscussion: Our findings offer a new model for classifying oral squamous cell carcinoma and determining its prognosis and offer novel insights into oral squamous cell carcinoma diagnosis and treatment.

Progress in the study of molecular mechanisms of cell pyroptosis in tumor therapy

Pyroptosis, also known as cellular inflammatory necrosis, is a programmed cell death mediated by the Gasdermin family of proteins. The mechanisms by which pyroptosis occurs are divided into the GSDMD-mediated Caspase-1 and Caspase-4/-5/-11-dependent classical inflammatory vesicle pathway and the GSDME-mediated Caspase-3 and granzyme-dependent non-classical inflammatory vesicle pathways, among others. Recent studies have shown that pyroptosis has both inhibitory and promotive effects on tumor development. Pyroptosis induction also plays a dual role in antitumor immunotherapy: on the one hand, it suppresses antitumor immunity by promoting the release of inflammatory factors, and on the other hand, it inhibits tumor cell proliferation by triggering antitumor inflammatory responses. In addition, cell scorching plays an essential role in chemotherapy. It has been found that natural drugs modulating the induction of cell scorch are necessary to treat tumors. Therefore, studying the specific mechanisms of cell pyroptosis in different tumors can provide more ideas for developing oncology drugs. In this paper, we review the molecular mechanisms of pyroptosis and the role of pyroptosis in tumor development and treatment to provide new targets for clinical tumor treatment, prognosis, and antitumor drug development.

ICI-based therapies: A new strategy for oral potentially malignant disorders

Oral potentially malignant disorders (OPMDs) are linked with an escalated risk of developing cancers, particularly oral squamous cell carcinoma (OSCC). Since prevailing therapies cannot effectively forestall the exacerbation and recurrence of OPMDs, halting their malignant progression is paramount. The immune checkpoint serves as a cardinal regulator of the immune response and the primary cause of adaptive immunological resistance. Although the exact mechanism remains elusive, elevated expression of multiple immune checkpoints in OPMDs and OSCC relative to healthy oral mucosa has been ascertained. This review delves into the immunosuppressive microenvironment of OPMDs, the expression of diverse immune checkpoints such as programmed death receptor-1 (PD-1) and programmed death receptor-1 ligand (PD-L1) in OPMDs, and the potential application of corresponding inhibitors. In addition, synergistic strategies incorporating combined immune checkpoint inhibitors, such as cGAS-STING, costimulatory molecules, cancer vaccines, and hydrogels, are discussed to gain a more comprehensive understanding of the role and application of immune checkpoint inhibitors (ICIs) in oral carcinogenesis.

Precancerous Lesions of the Head and Neck Region and Their Stromal Aberrations: Piecemeal Data

Head and neck squamous cell carcinomas (HNSCCs) develop through a series of precancerous stages from a pool of potentially malignant disorders (PMDs). Although we understand the genetic changes that lead to HNSCC, our understanding of the role of the stroma in the progression from precancer to cancer is limited. The stroma is the primary battleground between the forces that prevent and promote cancer growth. Targeting the stroma has yielded promising cancer therapies. However, the stroma at the precancerous stage of HNSCCs is poorly defined, and we may miss opportunities for chemopreventive interventions. PMDs already exhibit many features of the HNSCC stroma, such as inflammation, neovascularization, and immune suppression. Still, they do not induce cancer-associated fibroblasts or destroy the basal lamina, the stroma's initial structure. Our review aims to summarize the current understanding of the transition from precancer to cancer stroma and how this knowledge can reveal opportunities and limitations for diagnostic, prognostic, and therapeutic decisions to benefit patients. We will discuss what may be needed to fulfill the promise of the precancerous stroma as a target to prevent progression to cancer.

Therapeutic targets and biomarkers of tumor immunotherapy: response versus non-response

Cancers are highly complex diseases that are characterized by not only the overgrowth of malignant cells but also an altered immune response. The inhibition and reprogramming of the immune system play critical roles in tumor initiation and progression. Immunotherapy aims to reactivate antitumor immune cells and overcome the immune escape mechanisms of tumors. Represented by immune checkpoint blockade and adoptive cell transfer, tumor immunotherapy has seen tremendous success in the clinic, with the capability to induce long-term regression of some tumors that are refractory to all other treatments. Among them, immune checkpoint blocking therapy, represented by PD-1/PD-L1 inhibitors (nivolumab) and CTLA-4 inhibitors (ipilimumab), has shown encouraging therapeutic effects in the treatment of various malignant tumors, such as non-small cell lung cancer (NSCLC) and melanoma. In addition, with the advent of CAR-T, CAR-M and other novel immunotherapy methods, immunotherapy has entered a new era. At present, evidence indicates that the combination of multiple immunotherapy methods may be one way to improve the therapeutic effect. However, the overall clinical response rate of tumor immunotherapy still needs improvement, which warrants the development of novel therapeutic designs as well as the discovery of biomarkers that can guide the prescription of these agents. Learning from the past success and failure of both clinical and basic research is critical for the rational design of studies in the future. In this article, we describe the efforts to manipulate the immune system against cancer and discuss different targets and cell types that can be exploited to promote the antitumor immune response.

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.

PD-L1 in oral squamous cell carcinoma: A key biomarker from the laboratory to the bedside

Objectives and background: Oral squamous cell carcinoma (OSCC) is a highly malignant disease with an increasing incidence. The need to improve therapeutic strategies for patients affected by OSCC is an urgent challenge. Currently, the advent of immunotherapy represents an important step toward this aim. Programmed cell death‐ligand 1 (PD‐L1), a membrane protein that can be expressed on tumor and inflammatory cells is a key biomarker whose expression is determined by means of immunohistochemistry and is necessary for selecting patients for immunotherapy. Methods: In this study, we review the methods of PD‐L1 assessment and outcomes achieved with immunotherapy in the treatment of OSCC patients. Results: Based on a meta‐analysis we demonstrate a lack of prognostic significance of PD‐L1 in OSCC. Conclusions: We also highlight unresolved issues including difficulties in standardizing PD‐L1 evaluation and discuss future opportunities such as leveraging digital pathology.

Dynamic changes of exhaustion features in T cells during oral carcinogenesis

OBJECTIVES

This study aimed to clarify the dynamic changes of exhaustion features in T cells during oral carcinogenesis.

MATERIALS AND METHODS

Mice were randomly divided into 4NQO group and control group. The exhaustion features of CD4+ and CD8+ T cells of both groups were detected by flow cytometry. Furthermore, multiplex immunohistochemistry was used to evaluate the expression of inhibitory receptors in human normal, dysplastic, and carcinogenesis tissues. Finally, anti-PD-1 antibody treatment was performed at the early premalignant phase of oral carcinogenesis.

RESULTS

The proportion of naive T cells in 4NQO group was lower than those in control group, while the proportion of effector memory T cells was higher in 4NQO group. The expression of inhibitory receptors on CD4+ and CD8+ T cells increased gradually during carcinogenesis. In contrast, the secretion of cytokines by CD4+ and CD8+ T cells decreased gradually with the progression stage. Strikingly, those changes occurred before the onset of oral carcinogenesis. The expression of inhibitory receptors on T cells increased gradually as the human tissues progressed from normal, dysplasia to carcinoma. Interestingly, PD-1 blockade at the early premalignant phase could reverse carcinogenesis progression by restoring T cell function.

CONCLUSIONS

T-cell dysfunction was established at the early premalignant phase of oral carcinogenesis; PD-1 blockade at the early premalignant phase can effectively reverse T-cell exhaustion features and then prevent carcinogenesis progression.

The Impact of m1A Methylation Modification Patterns on Tumor Immune Microenvironment and Prognosis in Oral Squamous Cell Carcinoma

N1-methyladenosine (m1A) modification widely participates in the occurrence and progression of numerous diseases. Nevertheless, the potential roles of m1A in the tumor immune microenvironment (TIME) are still not fully understood. Based on 10 m1A methylation regulators, we comprehensively explored the m1A modification patterns in 502 patients with oral squamous cell carcinoma (OSCC). The m1A modification patterns were correlated with TIME characteristics and the m1A score was established to evaluate the effect of the m1A modification patterns on individual OSCC patients. The TIME characteristics and survival outcomes under the three m1A modification patterns were significantly distinct. OSCC patients in the high m1A score group were characterized by poorer prognosis, lower immune infiltration, lower ssGSEA score, lower expression levels of immune checkpoint molecules, and higher tumor mutation loads. The present study revealed that m1A modification might be associated with the TIME in OSCC, and has potential predictive ability for the prognosis of OSCC.