Establishment of syngeneic murine model for oral cancer therapy

FAP is a prognostic marker, but not a viable therapeutic target for clinical translation in HNSCC

PURPOSE

PD-1 targeted immunotherapy has imparted a survival benefit to advanced head and neck squamous cell carcinoma (HNSCC), but less than 20% patients produce a durable response to this therapy. Here we aimed to investigate the potential biomarkers for predicting the clinical outcome and resistance to PD-1 targeted immunotherapy in HNSCC patients, and to examine the involvement of FAP+ cancer-associated fibroblasts (CAFs).

METHODS

Bioinformatics methods were applied to analyze multiple datasets and explore the role of PD-1 and FAP in HNSCC. Immunohistochemistry was used to detect the expression of FAP protein. Fap gene knockout mice (Fap-/-) and L929 cells with different levels of Fap overexpression (L929-Fap-Low/High) were established to demonstrate the role of FAP+ CAFs in tumor development and immune checkpoint blockade (ICB) resistance.

RESULTS

The expression level of PD-1 gene was positively correlated with better overall survival and therapeutic response to PD-1 blockade in HNSCC, but not all tumors with high expression of both PD-1 and PD-L1 were responsive. Moreover, FAP gene was overexpressed in pan-cancer tissues, and could serve as a prognostic biomarker for several cancers, including HNSCC. However, FAP protein was undetectable in mouse MTCQ1 tumors and barely expressed in human HNSCC tumors. Furthermore, FAP+ CAFs did not promote tumor growth or enhance the resistance to PD-1 inhibitor treatment.

CONCLUSION

Although FAP+ CAFs have attracted increasing attention for their role in cancer, the feasibility and efficacy of FAP-targeting therapies for HNSCC remain doubtful.

Development of an integrated dual-modality 3D bioluminescence tomography and ultrasound imaging system for small animal tumor imaging

Ultrasound (US) is a valuable tool for imaging soft tissue and visualizing tumor contours. Taking the benefits of US, we presented an integrated dual-modality imaging system in this paper that achieves three-dimensional (3D) bioluminescence tomography (BLT) with multi-view bioluminescence images and 3D US imaging. The purpose of this system is to perform non-invasive, long-term monitoring of tumor growth in 3D images. US images can enhance the accuracy of the 3D BLT reconstruction and the bioluminescence dose within an object. Furthermore, an integrated co-registered scanning geometry was used to capture the fused BLT and US images. We validated the system with an in vivo experiment involving tumor-bearing mice. The results demonstrated the feasibility of reconstructing 3D BLT images in the tumor region using 3D US images. We used the dice coefficient and locational error to evaluate the similarity between the reconstructed source region and the actual source region. The dice coefficient was 88.5%, and the locational error was 0.4 mm when comparing the BLT and 3D US images. The hybrid BLT/US system could provide significant benefits for reconstructing the source of tumor location and conducting quantitative analysis of tumor size.

Targeting tumor O-glycosylation modulates cancer-immune-cell crosstalk and enhances anti-PD-1 immunotherapy in head and neck cancer

Cells in the tumor microenvironment (TME) communicate via membrane-bound and secreted proteins, which are mostly glycosylated. Altered glycomes of malignant tumors influence behaviors of stromal cells. In this study, we showed that the loss of core-1 β1,3-galactosyltransferase (C1GALT1)-mediated O-glycosylation suppressed tumor growth in syngeneic head and neck cancer mouse models. O-glycan truncation in tumor cells promoted the M1 polarization of macrophages, enhanced T-cell-mediated cytotoxicity, and reduced interleukin-6 (IL-6) levels in the secretome. Proteasomal degradation of IL-6 was controlled by the O-glycan at threonine 166. Both IL-6/IL-6R blockade and O-glycan truncation in tumor cells induced similar pro-inflammatory phenotypes in macrophages and cytotoxic T lymphocytes (CTLs). The combination of the O-glycosylation inhibitor itraconazole and anti-programmed cell death protein 1 (anti-PD-1) antibody effectively suppressed tumor growth in vivo. Collectively, our findings demonstrate that O-glycosylation in tumor cells governs their crosstalk with macrophages and CTLs. Thus, targeting O-glycosylation successfully reshapes the TME and consequently enhances the efficacy of anti-PD-1 therapy.

A modified SELEX approach to identify DNA aptamers with binding specificity to the major histocompatibility complex presenting ovalbumin model antigen

Aptamers have sparked significant interest in cell recognition because of their superior binding specificity and biocompatibility. Cell recognition can be mediated by targeting the major histocompatibility complex (MHC) that presents short peptides derived from intracellular antigens. Although numerous antibodies have demonstrated a specific affinity for the peptide-MHC complex, the number of aptamers that exhibit comparable characteristics is limited. Aptamers are usually selected from large libraries via the Systemic Evolution of Ligands by Exponential Enrichment (SELEX), an iterative process of selection and PCR amplification to enrich a pool of aptamers with high affinity. However, the success rate of aptamer identification is low, possibly due to the presence of complementary sequences or sequences rich in guanine and cytosine that are less accessible for primers. Here, we modified SELEX by employing systemic consecutive selections with minimal PCR amplification. We also modified the analysis by selecting aptamers that were identified in multiple selection rounds rather than those that are highly enriched. Using this approach, we were able to identify two aptamers with binding specificity to cells expressing the ovalbumin alloantigen as a proof of concept. These two aptamers were also discovered among the top 150 abundant candidates, despite not being highly enriched, by performing conventional SELEX. Additionally, we found that highly enriched aptamers tend to contain fractions of the primer sequence and have minimal target affinity. Candidate aptamers are easily missed in the conventional SELEX process. Therefore, our modification for SELEX may facilitate the identification of aptamers for more application in diverse biomedical fields. Significance: we modify the conventional method to improve the efficiency in the identification of the aptamer, a single strand of nucleic acid with binding specificity to the target molecule, showing as a proof of concept that this approach is particularly useful to select aptamers that can selectively bind to cells presenting a particular peptide by the major histocompatibility complex (MHC) on the cell surface. Given that cancer cells may express mutant peptide-MHC complexes that are distinct from those expressed by normal cells, this study sheds light on the potential application of aptamers to cancer cell targeting.

Exploring animal models in oral cancer research and clinical intervention: A critical review

Cancer is a leading cause of death worldwide, but advances in treatment, early detection, and prevention have helped to reduce its impact. To translate cancer research findings into clinical interventions for patients, appropriate animal experimental models, particularly in oral cancer therapy, can be helpful. In vitro experiments using animal or human cells can provide insight into cancer's biochemical pathways. This review discusses the various animal models used in recent years for research and clinical intervention in oral cancer, along with their advantages and disadvantages. We highlight the advantages and limitations of the used animal models in oral cancer research and therapy by searching the terms of animal models, oral cancer, oral cancer therapy, oral cancer research, and animals to find all relevant publications during 2010-2023. Mouse models, widely used in cancer research, can help us understand protein and gene functions in vivo and molecular pathways more deeply. To induce cancer in rodents, xenografts are often used, but companion animals with spontaneous tumours are underutilized for rapid advancement in human and veterinary cancer treatments. Like humans with cancer, companion animals exhibit biological behaviour, treatment responses, and cytotoxic agent responses similar to humans. In companion animal models, disease progression is more rapid, and the animals have a shorter lifespan. Animal models allow researchers to study how immune cells interact with cancer cells and how they can be targeted specifically. Additionally, animal models have been extensively used in research on oral cancers, so researchers can use existing knowledge and tools to better understand oral cancers using animal models.

Ferroptosis Signature Shapes the Immune Profiles to Enhance the Response to Immune Checkpoint Inhibitors in Head and Neck Cancer

As a type of immunogenic cell death, ferroptosis participates in the creation of immunoactive tumor microenvironments. However, knowledge of spatial location of tumor cells with ferroptosis signature in tumor environments and the role of ferroptotic stress in inducing the expression of immune-related molecules in cancer cells is limited. Here the spatial association of the transcriptomic signatures is demonstrated for ferroptosis and inflammation/immune activation located in the invasive front of head and neck squamous cell carcinoma (HNSCC). The association between ferroptosis signature and inflammation/immune activation is more prominent in HPV-negative HNSCC compared to HPV-positive ones. Ferroptotic stress induces PD-L1 expression through reactive oxygen species (ROS)-elicited NF-κB signaling pathway and calcium influx. Priming murine HNSCC with the ferroptosis inducer sensitizes tumors to anti-PD-L1 antibody treatment. A positive correlation between the ferroptosis signature and the active immune cell profile is shown in the HNSCC samples. This study reveals a subgroup of ferroptotic HNSCC with immune-active signatures and indicates the potential of priming HNSCC with ferroptosis inducers to increase the antitumor efficacy of immune checkpoint inhibitors.

Mouse Models for Immune Checkpoint Blockade Therapeutic Research in Oral Cancer

The most prevalent oral cancer globally is oral squamous cell carcinoma (OSCC). The invasion of adjacent bones and the metastasis to regional lymph nodes often lead to poor prognoses and shortened survival times in patients with OSCC. Encouraging immunotherapeutic responses have been seen with immune checkpoint inhibitors (ICIs); however, these positive responses to monotherapy have been limited to a small subset of patients. Therefore, it is urgent that further investigations into optimizing immunotherapies are conducted. Areas of research include identifying novel immune checkpoints and targets and tailoring treatment programs to meet the needs of individual patients. Furthermore, the advancement of combination therapies against OSCC is also critical. Thus, additional studies are needed to ensure clinical trials are successful. Mice models are advantageous in immunotherapy research with several advantages, such as relatively low costs and high tumor growth success rate. This review paper divided methods for establishing OSCC mouse models into four categories: syngeneic tumor models, chemical carcinogen induction, genetically engineered mouse, and humanized mouse. Each method has advantages and disadvantages that influence its application in OSCC research. This review comprehensively surveys the literature and summarizes the current mouse models used in immunotherapy, their advantages and disadvantages, and details relating to the cell lines for oral cancer growth. This review aims to present evidence and considerations for choosing a suitable model establishment method to investigate the early diagnosis, clinical treatment, and related pathogenesis of OSCC.

Snail-regulated exosomal microRNA-21 suppresses NLRP3 inflammasome activity to enhance cisplatin resistance

BACKGROUND

Compared with the precise targeting of drug-resistant mutant cancer cells, strategies for eliminating non-genetic adaptation-mediated resistance are limited. The pros and cons of the existence of inflammasomes in cancer have been reported. Nevertheless, the dynamic response of inflammasomes to therapies should be addressed.

METHODS

Tumor-derived exosomes were purified by differential ultracentrifugation and validated by nanoparticle tracking analysis and transmission electron microscopy. A proximity ligation assay and interleukin-1β (IL-1β) level were used for detecting activation of NLRP3 inflammasomes. RNA sequencing was used to analyze the exosomal RNAs. MIR21 knocked out human monocytic THP cells and mir21 knocked out murine oral cancer MTCQ1 cells were generated for confirming the exosomal delivery of microRNA (miR)-21. Syngeneic murine models for head and neck cancer (C57BLJ/6J), breast cancer (BALB/C) and lung cancer (C57BL/6J) were applied for examining the impact of Snail-miR21 axis on inflammasome activation in vivo. Single-cell RNA sequencing was used for analyzing the tumor-infiltrated immune cells. Head and neck patient samples were used for validating the findings in clinical samples.

RESULTS

We demonstrated that in cancer cells undergoing Snail-induced epithelial-mesenchymal transition (EMT), tumor cells suppress NLRP3 inflammasome activities of tumor-associated macrophages (TAMs) in response to chemotherapy through the delivery of exosomal miR-21. Mechanistically, miR-21 represses PTEN and BRCC3 to facilitate NLRP3 phosphorylation and lysine-63 ubiquitination, inhibiting NLRP3 inflammasome assembly. Furthermore, the Snail-miR-21 axis shapes the post-chemotherapy tumor microenvironment (TME) by repopulating TAMs and by activating CD8⁺ T cells. In patients with head and neck cancer, the Snail-high cases lacked post-chemotherapy IL-1β surge and were correlated with a worse response.

CONCLUSIONS

This finding reveals the mechanism of EMT-mediated resistance beyond cancer stemness through modulation of post-treatment inflammasome activity. It also highlights the dynamic remodeling of the TME throughout metastatic evolution.

Biomarkers and 3D models predicting response to immune checkpoint blockade in head and neck cancer (Review)

Immunotherapy has evolved into a powerful tool in the fight against a number of types of cancer, including head and neck squamous cell carcinomas (HNSCC). Although checkpoint inhibition (CPI) has definitely enriched the treatment options for advanced stage HNSCC during the past decade, the percentage of patients responding to treatment is widely varying between 14-32% in second-line setting in recurrent or metastatic HNSCC with a sporadic durability. Clinical response and, consecutively, treatment success remain unpredictable in most of the cases. One potential factor is the expression of target molecules of the tumor allowing cancer cells to acquire therapy resistance mechanisms. Accordingly, analyzing and modeling the complexity of the tumor microenvironment (TME) is key to i) stratify subgroups of patients most likely to respond to CPI and ii) to define new combinatorial treatment regimens. Particularly in a heterogeneous disease such as HNSCC, thoroughly studying the interactions and crosstalking between tumor and TME cells is one of the biggest challenges. Sophisticated 3D models are therefore urgently needed to be able to validate such basic science hypotheses and to test novel immuno-oncologic treatment regimens in consideration of the individual biology of each tumor. The present review will first summarize recent findings on immunotherapy, predictive biomarkers, the role of the TME and signaling cascades eliciting during CPI. Second, it will highlight the significance of current promising approaches to establish HNSCC 3D models for new immunotherapies. The results are encouraging and indicate that data obtained from patient-specific tumors in a dish might be finally translated into personalized immuno-oncology.

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.

Development of Stereo NIR-II Fluorescence Imaging System for 3D Tumor Vasculature in Small Animals

Near-infrared-II (NIR-II, 1000–1700 nm) fluorescence imaging boasts high spatial resolution and deep tissue penetration due to low light scattering, reduced photon absorption, and low tissue autofluorescence. NIR-II biological imaging is applied mainly in the noninvasive visualization of blood vessels and tumors in deep tissue. In the study, a stereo NIR-II fluorescence imaging system was developed for acquiring three-dimension (3D) images on tumor vasculature in real-time, on top of the development of fluorescent semiconducting polymer dots (IR-TPE Pdots) with ultra-bright NIR-II fluorescence (1000–1400 nm) and high stability to perform long-term fluorescence imaging. The NIR-II imaging system only consists of one InGaAs camera and a moving stage to simulate left-eye view and right-eye view for the construction of 3D in-depth blood vessel images. The system was validated with blood vessel phantom of tumor-bearing mice and was applied successfully in obtaining 3D blood vessel images with 0.6 mm- and 5 mm-depth resolution and 0.15 mm spatial resolution. The NIR-II stereo vision provides precise 3D information on the tumor microenvironment and blood vessel path.

Establishment of a p53 Null Murine Oral Carcinoma Cell Line and the Identification of Genetic Alterations Associated with This Carcinoma

Head and neck squamous cell carcinoma (HNSCC), including oral squamous cell carcinoma (OSCC), ranks sixth in cancer incidence worldwide. To generate OSCC cells lines from human or murine tumors, greatly facilitates investigations into OSCC. This study describes the establishing of a mouse palatal carcinoma cell line (designated MPC-1) from a spontaneous tumor present in a heterozygous p53 gene loss C57BL/6 mouse. A MPC-1-GFP cell subclone was then generated by lentivirus infection resulting in stable expression of green fluorescent protein. Assays indicated that MPC-1 was a p53 null polygonal cell that was positive for keratinocyte markers; it also expressed vimentin and showed a loss of E-cadherin expression. Despite that MPC-1 having strong proliferation and colony formation capabilities, the potential for anchorage independent growth and tumorigenesis was almost absent. Like other murine MOC-L and MTCQ cell line series we have previously established, MPC-1 also expresses a range of stemness markers, various oncogenic proteins, and a number of immune checkpoint proteins at high levels. However, the synergistic effects of the CDK4/6 inhibitor palbociclib on other therapeutic drugs were not observed with MPC-1. Whole exon sequencing revealed that there were high rates of non-synonymous mutations in MPC-1 affecting various genes, including Akap9, Arap2, Cdh11, Hjurp, Mroh2a, Muc4, Muc6, Sp110, and Sp140, which are similar to that the mutations present in a panel of chemical carcinogenesis-related murine tongue carcinoma cell lines. Analysis has highlighted the dis-regulation of Akap9, Cdh11, Muc4, Sp110, and Sp140 in human HNSCC as indicated by the TCGA and GEO OSCC databases. Sp140 expression has also been associated with patient survival. This study describes the establishment and characterization of the MPC-1 cell line and this new cell model should help to advance genetic research into oral cancer.

Development of lung metastases in mouse models of tongue squamous cell carcinoma

OBJECTIVE

Oral squamous cell carcinoma (OSCC) represents 3%-4% of all cancers. Despite the increasing incidence of OSCC distant metastasis and poor prognosis, few animal models of OSCC distant metastasis have been reported. In this study, we established mouse models of OSCC lung metastasis by orthotopic and tail vein injection of new OSCC cell lines.

METHODS

For the tail vein model, we used a novel cell line isolated from lung metastases reproduced in vivo after intravenous injection of HSC-3 GFP/luciferase cells and sorted for GFP expression (HSC-3 M1 GFP/luciferase). Lung metastases were assessed by imaging techniques and further confirmed by histology. For the orthotopic model, HSC-3 GFP/luciferase cells were injected into the tongue of athymic nude mice. The primary tumor and metastases were assessed by in vivo imaging, histology, and immunohistochemistry.

RESULTS

The orthotopic model presented spontaneous lung metastases in 50% of the animals and lymph node metastases were present in 83% of cases. In the tail vein model, a lung metastasis rate of 60% was observed.

CONCLUSIONS

Lung metastases were successfully reproduced by orthotopic and tail vein injection. Since lymph node metastases were present, the orthotopic model with HSC-3 GFP/luciferase cells may be suitable to investigate metastatic dissemination in OSCC.

Orthotopic tongue squamous cell carcinoma (SCC) model exhibiting a different tumor-infiltrating T-cell status with margin-restricted CD8+ T cells and regulatory T cell-dominance, compared to skin SCC

The immunological, and especially T cell, status of the tumor microenvironment affects tumor development and the efficacy of cancer treatment. To devise suitable combination therapies based on the results of murine tumor models, a more realistic orthotopic model is required. In this study, we generated a murine model of tongue squamous cell carcinoma (SCC), in which the tumor-immune cell interactions were recapitulated, and examined tumor- and T-cell status compared to a skin-transplanted SCC model by multiplex immunofluorescence staining for epidermal growth factor receptor, CD31, CD8, CD4, and Foxp3. Administration of SCCVII cells did not induce undesirable tissue damage or inflammation. In tongue SCC, abundant T-cell infiltration was observed at the tumor margin, but not in the core. Tongue SCC predominantly showed CD8⁺ T or Foxp3⁺ regulatory T cell (Treg)-infiltration. In contrast, skin-transplanted SCC showed abundant infiltration of T cells in the whole tumor area, which was dominated by Tregs. An orthotopic tongue SCC model showed differences in tumor and T-cell status compared to the skin-transplanted SCC model. Our tongue SCC model may enhance understanding of tumor-host interactions and enable evaluation of therapeutic efficacy.

Development and Radiation Response Assessment in A Novel Syngeneic Mouse Model of Tongue Cancer: 2D Culture, 3D Organoids and Orthotopic Allografts

Oral squamous cell carcinoma (OSCC) are aggressive cancers that contribute to significant morbidity and mortality in humans. Although numerous human xenograft models of OSCC have been developed, only a few syngeneic models of OSCC exist. Here, we report on a novel murine model of OSCC, RP-MOC1, derived from a tongue tumor in a C57Bl/6 mouse exposed to the carcinogen 4-nitroquinoline-1-oxide. Phenotypic characterization and credentialing (STR profiling, exome sequencing) of RP-MOC1 cells was performed in vitro. Radiosensitivity was evaluated in 2D culture, 3D organoids, and in vivo using orthotopic allografts. RP-MOC1 cells exhibited a stable epithelial phenotype with proliferative, migratory and invasive properties. Exome sequencing identified several mutations commonly found in OSCC patients. The LD₅₀ for RP-MOC1 cells in 2D culture and 3D organoids was found to be 2.4 Gy and 12.6 Gy, respectively. Orthotopic RP-MOC1 tumors were pan-cytokeratin+ and Ki-67+. Magnetic resonance imaging of orthotopic RP-MOC1 tumors established in immunocompetent mice revealed marked growth inhibition following 10 Gy and 15 Gy fractionated radiation regimens. This radiation response was completely abolished in tumors established in immunodeficient mice. This novel syngeneic model of OSCC can serve as a valuable platform for the evaluation of combination strategies to enhance radiation response against this deadly disease.

Mouse Tumor-Bearing Models as Preclinical Study Platforms for Oral Squamous Cell Carcinoma

Preclinical animal models of oral squamous cell carcinoma (OSCC) have been extensively studied in recent years. Investigating the pathogenesis and potential therapeutic strategies of OSCC is required to further progress in this field, and a suitable research animal model that reflects the intricacies of cancer biology is crucial. Of the animal models established for the study of cancers, mouse tumor-bearing models are among the most popular and widely deployed for their high fertility, low cost, and molecular and physiological similarity to humans, as well as the ease of rearing experimental mice. Currently, the different methods of establishing OSCC mouse models can be divided into three categories: chemical carcinogen-induced, transplanted and genetically engineered mouse models. Each of these methods has unique advantages and limitations, and the appropriate application of these techniques in OSCC research deserves our attention. Therefore, this review comprehensively investigates and summarizes the tumorigenesis mechanisms, characteristics, establishment methods, and current applications of OSCC mouse models in published papers. The objective of this review is to provide foundations and considerations for choosing suitable model establishment methods to study the relevant pathogenesis, early diagnosis, and clinical treatment of OSCC.