Sensory Neurotransmitter Calcitonin Gene-Related Peptide Modulates Tumor Growth and Lymphocyte Infiltration in Oral Squamous Cell Carcinoma

Nociceptive neurons promote gastric tumour progression via a CGRP-RAMP1 axis

Cancer cells have been shown to exploit neurons to modulate their survival and growth, including through the establishment of neural circuits within the central nervous system1-3. Here we report a distinct pattern of cancer-nerve interactions between the peripheral nervous system and gastric cancer. In multiple mouse models of gastric cancer, nociceptive nerves demonstrated the greatest degree of nerve expansion in an NGF-dependent manner. Neural tracing identified CGRP+ peptidergic neurons as the primary gastric sensory neurons. Three-dimensional co-culture models showed that sensory neurons directly connect with gastric cancer spheroids. Chemogenetic activation of sensory neurons induced the release of calcium into the cytoplasm of cancer cells, promoting tumour growth and metastasis. Pharmacological ablation of sensory neurons or treatment with CGRP inhibitors suppressed tumour growth and extended survival. Depolarization of gastric tumour membranes through in vivo optogenetic activation led to enhanced calcium flux in jugular nucleus complex and CGRP release, defining a cancer cell-peptidergic neuronal circuit. Together, these findings establish the functional connectivity between cancer and sensory neurons, identifying this pathway as a potential therapeutic target.

Tumor cells induce neural DKK1 expression to promote MDSC infiltration and subsequent T cell suppression

Nerves are often overlooked as key components of the tumor microenvironment. However, the molecular mechanisms underlying the reciprocal interactions between tumors and nerves remain largely unknown. In this study, we analyzed data from The Cancer Genome Atlas (TCGA) and identified a significant association between DKK1 expression and poor prognosis, as well as a correlation between DKK1 expression and myeloid-derived suppressor cell (MDSC) infiltration in head and neck squamous cell carcinoma (HNSCC) and pancreatic ductal adenocarcinoma (PDAC), two cancer types characterized by pronounced tumor-nerve interactions. Based on these findings, we hypothesize that tumors may induce DKK1 expression in nerves, and that nerve-derived DKK1 may promote MDSC infiltration and immunosuppression. To test this hypothesis, we employed a combination of experimental approaches, including in vitro co-culture of trigeminal ganglia with tumor cells, multiplex immunohistochemistry, and in vivo administration of DKK1 neutralizing antibodies. Our results indicate that tumor cells significantly induce DKK1 expression in ganglia in co-culture experiments. Additionally, in vivo orthotopic tumor models revealed that DKK1 levels were markedly elevated in both the plasma and ganglia of tumor-bearing mice. Neutralization DKK1 in vivo led to a reduction in MDSC levels and impaired MDSC-mediated T cell suppression in both HNSCC and PDAC orthotopic models. Furthermore, conditional deletion of neuronal DKK1 elucidated its role in MDSC infiltration and immune suppression. Our findings establish a novel molecular axis in which tumor cells modulate the immune microenvironment by inducing the expression of secreted proteins in nerves, thereby enriching the research landscape of the tumor microenvironment.

Tumor-nerve interactions in cancer regulation and progression

Tumor-nerve interactions play a critical role in tumor progression, metastasis, and treatment resistance, redefining our understanding of the tumor microenvironment. This review provides a comprehensive analysis of how the peripheral and central nervous systems contribute to cancer biology, focusing on mechanisms of neural invasion, immune evasion, and tumor adaptation. It has highlighted the emerging potential of repurposing nervous system-targeted drugs originally developed for neurodegenerative and autoimmune diseases as innovative cancer therapies. The review also addresses key challenges, including the limitations of current experimental models and the complexity of translating preclinical findings to clinical applications. By bridging the gap between neuroscience and oncology, this interdisciplinary study aims to discover novel therapeutic strategies to improve outcomes for cancer patients.

Capsaicin-induced Ca2+ overload and ablation of TRPV1-expressing axonal terminals for comfortable tumor immunotherapy

As a common malignancy symptom, cancer pain significantly affects patients' quality of life. Approximately 60%-90% of patients with advanced cancer experience debilitating pain. Therefore, a comprehensive treatment system that combines cancer pain suppression and tumor treatment could provide significant benefits for these patients. Here, we designed a manganese oxide (MnO2)/Bovine serum albumin (BSA)/polydopamine (PDA) composite nanoplatform internally loaded with capsaicin for cancer pain suppression and immunotherapy. MBD&C nanoparticles (NPs) can ablate tumor-innervated sensory nerve fibers via Transient receptor potential vanilloid 1 (TRPV1) channels, thereby reducing the pain caused by various inflammatory mediators. The ablation of TRPV1+ nerve terminals can also decrease the secretion of calcitonin gene-related peptide (CGRP) and substance P (SP) in sensory nerve fibers, thus reducing the tumor pain and inhibit tumor progression. MBD&C can promote calcium influx by activating overexpressed TRPV1 channels on the tumor membrane surface, thereby achieving cancer immunotherapy induced by endogenous Ca2+ overloading. In addition, MnO2 NPs can alleviate tumor hypoxia and mitigate the immunosuppressive tumor microenvironment (TME). Ultimately, this treatment system with dual capabilities of inhibiting tumor growth and relieving cancer pain makes comfortable tumor therapy feasible and paves the way for the development of patient-centered approaches to cancer treatment in the future.

Understanding the role of nerves in head and neck cancers - a review

Worldwide, head and neck cancers (HNCs) account for approximately 900,000 cases and 500,000 deaths annually, with their incidence continuing to rise. Carcinogenesis is a complex, multidimensional molecular process leading to cancer development, and in recent years, the role of nerves in the pathogenesis of various malignancies has been increasingly recognized. Thanks to the abundant innervation of the head and neck region, peripheral nervous system has gained considerable interest for its possible role in the development and progression of HNCs. Intratumoral parasympathetic, sympathetic, and sensory nerve fibers are emerging as key players and potential targets for novel anti-cancer and pain-relieving medications in different tumors, including HNCs. This review explores nerve-cancer interactions, including perineural invasion (PNI), cancer-related axonogenesis, neurogenesis, and nerve reprogramming, with an emphasis on their molecular mechanisms, mediators and clinical implications. PNI, an adverse histopathologic feature, has been widely investigated in HNCs. However, its prognostic value remains debated due to inconsistent results when classified dichotomously (present/absent). Emerging evidence suggests that quantitative and qualitative descriptions of PNI may better reflect its clinical usefulness. The review also examines therapies targeting nerve-cancer crosstalk and highlights the influence of HPV status on tumor innervation. By synthesizing current knowledge, challenges, and future perspectives, this review offers insights into the molecular basis of nerve involvement in HNCs and the potential for novel therapeutic approaches.

Neuroscience of cancer: unraveling the complex interplay between the nervous system, the tumor and the tumor immune microenvironment

The study of the multifaceted interactions between neuroscience and cancer is an emerging field with significant implications for understanding tumor biology and the innovation in therapeutic approaches. Increasing evidence suggests that neurological functions are connected with tumorigenesis. In particular, the peripheral and central nervous systems, synapse, neurotransmitters, and neurotrophins affect tumor progression and metastasis through various regulatory approaches and the tumor immune microenvironment. In this review, we summarized the neurological functions that affect tumorigenesis and metastasis, which are controlled by the central and peripheral nervous systems. We also explored the roles of neurotransmitters and neurotrophins in cancer progression. Moreover, we examined the interplay between the nervous system and the tumor immune microenvironment. We have also identified drugs that target the nervous system for cancer treatment. In this review we present the work supporting that therapeutic agent targeting the nervous system could have significant potential to improve cancer therapy.

Nerves at Play: The Peripheral Nervous System in Extracranial Malignancies

The exponential growth of the cancer neuroscience field has shown that the host's immune, vascular, and nervous systems communicate with and influence each other in the tumor microenvironment, dictating the cancer malignant phenotype. Unraveling the nervous system's contributions toward this phenotype brings us closer to cancer cures. In this review, we summarize the peripheral nervous system's contributions to cancer. We highlight the effects of nerve recruitment and tumor innervation, the neuro-immune axis, glial cell activity, and neural regulation on cancer development and progression. We also discuss harnessing the neural control of peripheral cancers as a potential therapeutic approach in oncology. Significance: The continued and growing interest in cancer neuroscience by the scientific and medical communities reflects the rapidly accumulating interdisciplinary understanding of the nervous system's modulation of immune, vascular, and cancer cells' functions in malignancies. Understanding these regulatory functions can identify targets for intervention that may already be clinically available for other indications. This potential brings great excitement and hope for patients with cancer worldwide.

Neural control of tumor immunity

Communication between the nervous system and the immune system has evolved to optimally respond to potentially dangerous stimuli both from within and outside the body. Tumors pose a severe threat to an organism and current therapies are insufficient for tumor regression in the majority of cases. Studies show that tumors are innervated by peripheral nerves from the sensory, parasympathetic and sympathetic nervous systems. Interactions between cancer cells, nerves and immune cells regulate overall tumor progression. Clinical studies have indicated the potential of targeting the peripheral nervous system for promoting anti-tumor immune responses. This view point provides an opinion on the current evidence and therapeutic potential of manipulating neuro-immune communications in cancer.

Neuroscience in peripheral cancers: tumors hijacking nerves and neuroimmune crosstalk

Cancer neuroscience is an emerging field that investigates the intricate relationship between the nervous system and cancer, gaining increasing recognition for its importance. The central nervous system governs the development of the nervous system and directly affects brain tumors, and the peripheral nervous system (PNS) shapes the tumor microenvironment (TME) of peripheral tumors. Both systems are crucial in cancer initiation and progression, with recent studies revealing a more intricate role of the PNS within the TME. Tumors not only invade nerves but also persuade them through remodeling to further promote malignancy, creating a bidirectional interaction between nerves and cancers. Notably, immune cells also contribute to this communication, forming a triangular relationship that influences protumor inflammation and the effectiveness of immunotherapy. This review delves into the intricate mechanisms connecting the PNS and tumors, focusing on how various immune cell types influence nerve‒tumor interactions, emphasizing the clinical relevance of nerve‒tumor and nerve‒immune dynamics. By deepening our understanding of the interplay between nerves, cancer, and immune cells, this review has the potential to reshape tumor biology insights, inspire innovative therapies, and improve clinical outcomes for cancer patients.

Harnessing brain-body communication to understand cancer

Solid tumors that arise in the body interact with neurons, which influences cancer progression and treatment response. Here, we discuss key questions in the field, including defining the nature of interactions between tumors and neural circuits and defining how neural signals shape the tumor microenvironment. This information will allow us to optimally target neural signaling to improve outcomes for cancer patients.

Targeting the peripheral neural-tumour microenvironment for cancer therapy

As the field of cancer neuroscience expands, the strategic targeting of interactions between neurons, cancer cells and other elements in the tumour microenvironment represents a potential paradigm shift in cancer treatment, comparable to the advent of our current understanding of tumour immunology. Cancer cells actively release growth factors that stimulate tumour neo-neurogenesis, and accumulating evidence indicates that tumour neo-innervation propels tumour progression, inhibits tumour-related pro-inflammatory cytokines, promotes neovascularization, facilitates metastasis and regulates immune exhaustion and evasion. In this Review, we give an up-to-date overview of the dynamics of the tumour microenvironment with an emphasis on tumour innervation by the peripheral nervous system, as well as current preclinical and clinical evidence of the benefits of targeting the nervous system in cancer, laying a scientific foundation for further clinical trials. Combining empirical data with a biomarker-driven approach to identify and hone neuronal targets implicated in cancer and its spread can pave the way for swift clinical integration.

The sympathetic nervous system shapes the tumor microenvironment to impair chemotherapy response

The tumor microenvironment influences cancer progression and response to treatments, which ultimately impacts the survival of patients with cancer. The sympathetic nervous system (SNS) is a core component of solid tumors that arise in the body. In addition to influencing cancer progression, a role for the SNS in the effectiveness of cancer treatments is beginning to emerge. This review explores evidence that the SNS impairs chemotherapy efficacy. We review findings of studies that evaluated the impact of neural ablation on chemotherapy outcomes and discuss plausible mechanisms for the impact of neural signaling on chemotherapy efficacy. We then discuss implications for clinical practice, including opportunities to block neural signaling to improve response to chemotherapy.

Tumor-infiltrating nerves functionally alter brain circuits and modulate behavior in a mouse model of head-and-neck cancer

Cancer patients often experience changes in mental health, prompting an exploration into whether nerves infiltrating tumors contribute to these alterations by impacting brain functions. Using a mouse model for head and neck cancer and neuronal tracing, we show that tumor-infiltrating nerves connect to distinct brain areas. The activation of this neuronal circuitry altered behaviors (decreased nest-building, increased latency to eat a cookie, and reduced wheel running). Tumor-infiltrating nociceptor neurons exhibited heightened calcium activity and brain regions receiving these neural projections showed elevated Fos as well as increased calcium responses compared to non-tumor-bearing counterparts. The genetic elimination of nociceptor neurons decreased brain Fos expression and mitigated the behavioral alterations induced by the presence of the tumor. While analgesic treatment restored nesting and cookie test behaviors, it did not fully restore voluntary wheel running indicating that pain is not the exclusive driver of such behavioral shifts. Unraveling the interaction between the tumor, infiltrating nerves, and the brain is pivotal to developing targeted interventions to alleviate the mental health burdens associated with cancer.

TUMOR-INFILTRATING NOCICEPTOR NEURONS PROMOTE IMMUNOSUPPRESSION

Nociceptor neurons impact tumor immunity. Removing nociceptor neurons reduced myeloid-derived suppressor cell (MDSCs) tumor infiltration in mouse models of head and neck carcinoma and melanoma. Carcinoma-released small extracellular vesicles (sEVs) attract nociceptive nerves to tumors. sEV-deficient tumors fail to develop in mice lacking nociceptor neurons. Exposure of dorsal root ganglia (DRG) neurons to cancer sEVs elevated expression of Substance P, IL-6 and injury-related neuronal markers while treatment with cancer sEVs and cytotoxic CD8 T-cells induced an immunosuppressive state (increased exhaustion ligands and cytokines). Cancer patient sEVs enhanced DRG responses to capsaicin, indicating increased nociceptor sensitivity. Conditioned media from DRG and cancer cell co-cultures promoted expression of MDSC markers in primary bone marrow cells while DRG conditioned media together with cancer sEVs induced checkpoint expression on T-cells. Our findings indicate that nociceptor neurons facilitate CD8+ T cell exhaustion and enhance MDSC infiltration. Targeting nociceptor-released IL-6 emerges as a novel strategy to disrupt harmful neuro-immune interactions in cancer and enhance anti-tumor immunity.

Tumor-associated genetic amplifications impact extracellular vesicle miRNA cargo and their recruitment of nerves in head and neck cancer

Cancer neuroscience is an emerging field of cancer biology focused on defining the interactions and relationships between the nervous system, developing malignancies, and their environments. Our previous work demonstrates that small extracellular vesicles (sEVs) released by head and neck squamous cell carcinomas (HNSCCs) recruit loco-regional nerves to the tumor. sEVs contain a diverse collection of biological cargo, including microRNAs (miRNAs). Here, we asked whether two genes commonly amplified in HNSCC, CCND1, and PIK3CA, impact the sEV miRNA cargo and, subsequently, sEV-mediated tumor innervation. To test this, we individually overexpressed these genes in a syngeneic murine HNSCC cell line, purified their sEVs, and tested their neurite outgrowth activity on dorsal root ganglia (DRG) neurons in vitro. sEVs purified from Ccnd1-overexpressing cells significantly increased neurite outgrowth of DRG compared to sEVs from parental or Pik3ca over-expressing cells. When implanted into C57BL/6 mice, Ccnd1 over-expressing tumor cells promoted significantly more tumor innervation in vivo. qPCR analysis of sEVs shows that increased expression of Ccnd1 altered the packaging of miRNAs (miR-15-5p, miR-17-5p, and miR-21-5p), many of which target transcripts important in regulating axonogenesis. These data indicate that genetic amplifications harbored by malignancies impose changes in sEV miRNA cargo, which can influence tumorc innervation.

Neuroimmune cell interactions and chronic infections in oral cancers

Inflammation is a process that is associated with the activation of distal immunosuppressive pathways that have evolved to restore homeostasis and prevent excessive tissue destruction. However, long-term immunosuppression resulting from systemic and local inflammation that may stem from dysbiosis, infections, or aging poses a higher risk for cancers. Cancer incidence and progression dramatically increase with chronic infections including HIV infection. Thus, studies on pro-tumorigenic effects of microbial stimulants from resident microbiota and infections in the context of inflammation are needed and underway. Here, we discuss chronic infections and potential neuro-immune interactions that could establish immunomodulatory programs permissive for tumor growth and progression.

Neuronal CFL1 upregulation in head and neck squamous cell carcinoma enhances tumor-nerve crosstalk and promotes tumor growth

Head and neck squamous cell carcinoma (HNSCC) is a prevalent cancer type, marked by a pronounced nerve density within the tumor microenvironment and a high rate of perineural invasion (PNI). Growing evidence suggests that the nervous system plays a vital role in HNSCC progression. Yet, the mechanisms governing cancer-nerve interactions remain largely elusive. Our research revealed that cofilin-1 (CFL1) is significantly overexpressed in HNSCC and correlates with both PNI and unfavorable prognosis. Utilizing multiplex fluorescent immunohistochemistry, we have localized CFL1 chiefly to the nerves adjacent to tumor sites. Significantly, it is the elevated expression of CFL1 in neuronal structures, rather than in the tumor cells, that aligns with diminished patient survival rates. We observed that HNSCC cells induced the expression of neuronal CFL1 and that the conditional knockout of neuronal CFL1 impedes tumor-nerve interactions. Both Gene Ontology functional enrichment analyses and Gene Set Enrichment Analysis demonstrate that CFL1 expression in HNSCC is associated with specific biological processes, including "RIBOSOME," "PROTEASOME," and "cadherin binding." In summary, HNSCC promotes the expression of CFL1 in nerves, which is essential for cancer-nerve interactions. The neuronal CFL1 is associated with PNI and may be a potential molecular prognostic marker of poor survival in HNSCC.

Modulation of host immunity by sensory neurons

Recent studies have uncovered a new role for sensory neurons in influencing mammalian host immunity, challenging conventional notions of the nervous and immune systems as separate entities. In this review we delve into this groundbreaking paradigm of neuroimmunology and discuss recent scientific evidence for the impact of sensory neurons on host responses against a wide range of pathogens and diseases, encompassing microbial infections and cancers. These valuable insights enhance our understanding of the interactions between the nervous and immune systems, and also pave the way for developing candidate innovative therapeutic interventions in immune-mediated diseases highlighting the importance of this interdisciplinary research field.

Periampullary cancer and neurological interactions: current understanding and future research directions

Periampullary cancer is a malignant tumor occurring around the ampullary region of the liver and pancreas, encompassing a variety of tissue types and sharing numerous biological characteristics, including interactions with the nervous system. The nervous system plays a crucial role in regulating organ development, maintaining physiological equilibrium, and ensuring life process plasticity, a role that is equally pivotal in oncology. Investigations into nerve-tumor interactions have unveiled their key part in controlling cancer progression, inhibiting anti-tumor immune responses, facilitating invasion and metastasis, and triggering neuropathic pain. Despite many mechanisms by which nerve fibers contribute to cancer advancement still being incompletely understood, the growing emphasis on the significance of nerves within the tumor microenvironment in recent years has set the stage for the development of groundbreaking therapies. This includes combining current neuroactive medications with established therapeutic protocols. This review centers on the mechanisms of Periampullary cancer's interactions with nerves, the influence of various types of nerve innervation on cancer evolution, and outlines the horizons for ongoing and forthcoming research.

Sensory nerve release of CGRP increases tumor growth in HNSCC by suppressing TILs

BACKGROUND

Perineural invasion (PNI) and nerve density within the tumor microenvironment (TME) have long been associated with worse outcomes in head and neck squamous cell carcinoma (HNSCC). This prompted an investigation into how nerves within the tumor microenvironment affect the adaptive immune system and tumor growth.

METHODS

We used RNA sequencing analysis of human tumor tissue from a recent HNSCC clinical trial, proteomics of human nerves from HNSCC patients, and syngeneic orthotopic murine models of HPV-unrelated HNSCC to investigate how sensory nerves modulate the adaptive immune system.

FINDINGS

Calcitonin gene-related peptide (CGRP) directly inhibited CD8 T cell activity in vitro, and blocking sensory nerve function surgically, pharmacologically, or genetically increased CD8 and CD4 T cell activity in vivo.

CONCLUSIONS

Our data support sensory nerves playing a role in accelerating tumor growth by directly acting on the adaptive immune system to decrease Th1 CD4 T cells and activated CD8 T cells in the TME. These data support further investigation into the role of sensory nerves in the TME of HNSCC and points toward the possible treatment efficacy of blocking sensory nerve function or specifically inhibiting CGRP release or activity within the TME to improve outcomes.

FUNDING

1R01DE028282-01, 1R01DE028529-01, 1P50CA261605-01 (to S.D.K.), 1R01CA284651-01 (to S.D.K.), and F31 DE029997 (to L.B.D.).

Nociceptive neurons interact directly with gastric cancer cells via a CGRP/Ramp1 axis to promote tumor progression

Cancer cells have been shown to exploit neurons to modulate their survival and growth, including through establishment of neural circuits within the central nervous system (CNS) 1-3 . Here, we report a distinct pattern of cancer-nerve interactions between the peripheral nervous system (PNS) and gastric cancer (GC). In multiple GC mouse models, nociceptive nerves demonstrated the greatest degree of nerve expansion in an NGF-dependent manner. Neural tracing identified CGRP+ peptidergic neurons as the primary gastric sensory neurons. Three-dimensional co-culture models showed that sensory neurons directly connect with gastric cancer spheroids through synapse-like structures. Chemogenetic activation of sensory neurons induced the release of calcium into the cytoplasm of cancer cells, promoting tumor growth and metastasis. Pharmacological ablation of sensory neurons or treatment with CGRP inhibitors suppressed tumor growth and extended survival. Depolarization of gastric tumor membranes through in vivo optogenetic activation led to enhanced calcium flux in nodose ganglia and CGRP release, defining a cancer cell-peptidergic neuronal circuit. Together, these findings establish the functional connectivity between cancer and sensory neurons, identifying this pathway as a potential therapeutic target.

From pain to tumor immunity: influence of peripheral sensory neurons in cancer

The nervous and immune systems are the primary sensory interfaces of the body, allowing it to recognize, process, and respond to various stimuli from both the external and internal environment. These systems work in concert through various mechanisms of neuro-immune crosstalk to detect threats, provide defense against pathogens, and maintain or restore homeostasis, but can also contribute to the development of diseases. Among peripheral sensory neurons (PSNs), nociceptive PSNs are of particular interest. They possess a remarkable capability to detect noxious stimuli in the periphery and transmit this information to the brain, resulting in the perception of pain and the activation of adaptive responses. Pain is an early symptom of cancer, often leading to its diagnosis, but it is also a major source of distress for patients as the disease progresses. In this review, we aim to provide an overview of the mechanisms within tumors that are likely to induce cancer pain, exploring a range of factors from etiological elements to cellular and molecular mediators. In addition to transmitting sensory information to the central nervous system, PSNs are also capable, when activated, to produce and release neuropeptides (e.g., CGRP and SP) from their peripheral terminals. These neuropeptides have been shown to modulate immunity in cases of inflammation, infection, and cancer. PSNs, often found within solid tumors, are likely to play a significant role in the tumor microenvironment, potentially influencing both tumor growth and anti-tumor immune responses. In this review, we discuss the current state of knowledge about the degree of sensory innervation in tumors. We also seek to understand whether and how PSNs may influence the tumor growth and associated anti-tumor immunity in different mouse models of cancer. Finally, we discuss the extent to which the tumor is able to influence the development and functions of the PSNs that innervate it.

Lingual Denervation Improves the Efficacy of Anti-PD-1 Immunotherapy in Oral Squamous Cell Carcinomas by Downregulating TGFβ Signaling

PURPOSE

Intratumoral nerve infiltration relates to tumor progression and poor survival in oral squamous cell carcinoma (OSCC). How neural involvement regulates antitumor immunity has not been well characterized. This study aims to investigate molecular mechanisms of regulating tumor aggressiveness and impairing antitumor immunity by nerve-derived factors.

EXPERIMENTAL DESIGN

We performed the surgical lingual denervation in an immunocompetent mouse OSCC model to investigate its effect on tumor growth and the efficacy of anti-PD-1 immunotherapy. A trigeminal ganglion neuron and OSCC cell coculture system was established to investigate the proliferation, migration, and invasion of tumor cells and the PD-L1 expression. Both the neuron-tumor cell coculture in vitro model and the OSCC animal model were explored.

RESULTS

Lingual denervation slowed down tumor growth and improved the efficacy of anti-PD-1 treatment in the OSCC model. Coculturing with neurons not only enhanced the proliferation, migration, and invasion but also upregulated TGFβ-SMAD2 signaling and PD-L1 expression of tumor cells. Treatment with the TGFβ signaling inhibitor galunisertib reversed nerve-derived tumor aggressiveness and downregulated PD-L1 on tumor cells. Similarly, lingual denervation in vivo decreased TGFβ and PD-L1 expression and increased CD8+ T-cell infiltration and the expression of IFNγ and TNFα within tumor.

CONCLUSIONS

Neural involvement enhanced tumor aggressiveness through upregulating TGFβ signaling and PD-L1 expression in OSCC, while denervation of OSCC inhibited tumor growth, downregulated TGFβ signaling, enhanced activities of CD8+ T cells, and improved the efficacy of anti-PD-1 immunotherapy. This study will encourage further research focusing on denervation as a potential adjuvant therapeutic approach in OSCC.

SIGNIFICANCE

This study revealed the specific mechanisms for nerve-derived cancer progression and impaired antitumor immunity in OSCC, providing a novel insight into the cancer-neuron-immune network as well as pointing the way for new strategies targeting nerve-cancer cross-talk as a potential adjuvant therapeutic approach for OSCC.

Activation of Transient Receptor Potential Vanilloid 1 Is Involved in Both Pain and Tumor Growth in a Mouse Model of Cancer Pain

Activation of calcitonin gene-related peptide (CGRP)-positive sensory neurons in the tumor microenvironment has been shown to be involved in tumor growth. However, how CGRP-positive sensory neurons are activated requires elucidation. In this study, we focused on transient receptor potential vanilloid 1 (TRPV1) and examined the contribution of TRPV1 to tumor growth and cancer pain in a mouse cancer model in which Lewis lung carcinoma was subcutaneously inoculated in the left plantar region. Tumor inoculation gradually increased the volumes of the hind paws of wild type (WT) mice over time, but those of both αCGRP knockout mice and TRPV1 knockout mice were significantly smaller than those of WT mice after tumor inoculation. Both TRPV1 and CGRP are therefore suggested to be involved in tumor growth. In an immunohistochemical study, the percentage of phosphorylated cyclic adenosine monophosphate response element-binding protein (p-CREB)-positive profiles in CGRP-positive dorsal root ganglion (DRG) neurons in WT mice was significantly increased after tumor inoculation. The percentage of p-CREB-positive profiles in CGRP-positive DRG neurons in TRPV1 knockout mice was also increased after tumor inoculation, but was significantly lower than that in WT mice, indicating the contribution of TRPV1 to activation of CGRP-positive DRG neurons. Cancer pain in TRPV1 knockout mice was significantly lower than that in WT mice. In conclusion, TRPV1 is involved in both tumor growth and cancer pain, potentially leading to a novel strategy for the treatment of cancer pain and cancer development. Cancer pain is also suggested to facilitate tumor growth.

Tumor Neurobiology in the Pathogenesis and Therapy of Head and Neck Cancer

The neurobiology of tumors has attracted considerable interest from clinicians and scientists and has become a multidisciplinary area of research. Neural components not only interact with tumor cells but also influence other elements within the TME, such as immune cells and vascular components, forming a polygonal relationship to synergistically facilitate tumor growth and progression. This review comprehensively summarizes the current state of the knowledge on nerve-tumor crosstalk in head and neck cancer and discusses the potential underlying mechanisms. Several mechanisms facilitating nerve-tumor crosstalk are covered, such as perineural invasion, axonogenesis, neurogenesis, neural reprogramming, and transdifferentiation, and the reciprocal interactions between the nervous and immune systems in the TME are also discussed in this review. Further understanding of the nerve-tumor crosstalk in the TME of head and neck cancer may provide new nerve-targeted treatment options and help improve clinical outcomes for patients.

Crosstalk Between Peripheral Innervation and Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive lethal malignancy, characterized by late diagnosis, aggressive growth, and therapy resistance, leading to a poor overall prognosis. Emerging evidence shows that the peripheral nerve is an important non-tumor component in the tumor microenvironment that regulates tumor growth and immune escape. The crosstalk between the neuronal system and PDAC has become a hot research topic that may provide novel mechanisms underlying tumor progression and further uncover promising therapeutic targets. In this review, we highlight the mechanisms of perineural invasion and the role of various types of tumor innervation in the progression of PDAC, summarize the potential signaling pathways modulating the neuronal-cancer interaction, and discuss the current and future therapeutic possibilities for this condition.

Lanthanum Oxide Nanoparticles Reinforced Collagen ƙ-Carrageenan Hydroxyapatite Biocomposite as Angio-Osteogenic Biomaterial for In Vivo Osseointegration and Bone Repair

A composite biomatrix fabricated with collagen, ƙ-carrageenan, hydroxyapatite reinforced with lanthanum oxide nanoparticles is explored as proangiogenic and osteogenic bone tissue repair biomaterial. The biomatrix shows increased physical and biological stability as observed from proteolytic degradation and thermal stability studies. The addition of lanthanum oxide nanoparticles facilitates good osseointegration coupled with simultaneous activation of proangiogenic properties to act as a bone mimicking material. The minimal level of reactive oxygen species and superior cytocompatibility help the as-synthesized biomatrix in achieving capillary migration into the bone micro environment. The composite biomatrix upregulates the expression of VEGF, VEGF-R2 genes in endothelial cells and osteopontin, osteocalcin in osteoblasts cells, respectively. The in vivo hard tissue repair experiment conducted in a rat model shows complete healing of the bone defect by eight weeks with the application of collagen-ƙ-carrageenan-hydroxyapatite-lanthanum oxide nanoparticle biomaterial when compared to the biomaterial made out of individual constituents alone. The biomaterial matrix gets biointegrated into the bone tissue and exerts its therapeutic value in bringing a faster osseo repair process. The study shows the feasibility of using rare-earth metal nanoparticles in combination with protein-polysaccharide biopolymers for bone regeneration.

Neuro-immune interactions and immuno-oncology

The nervous system is an important component of the tumor microenvironment (TME), driving tumorigenesis and tumor progression. Neuronal cues (e.g., neurotransmitters and neuropeptides) in the TME cause phenotypic changes in immune cells, such as increased exhaustion and inhibition of effector cells, which promote immune evasion and cancer progression. Two types of immune regulation by tumor-associated nerves are discussed in this review: regulation via neuronal stimuli (i.e., by neural transmission) and checkpoint-mediated neuronal immune regulation. The latter occurs via the expression of immune checkpoints on the membranes of intratumoral nerves and glial cells. Here, we summarize novel findings regarding the neuroimmune circuits in the tumor milieu, while emphasizing the potential targets of new and affordable anticancer therapeutic approaches.

Calcitonin Related Polypeptide Alpha Mediates Oral Cancer Pain

Oral cancer patients suffer pain at the site of the cancer. Calcitonin gene related polypeptide (CGRP), a neuropeptide expressed by a subset of primary afferent neurons, promotes oral cancer growth. CGRP also mediates trigeminal pain (migraine) and neurogenic inflammation. The contribution of CGRP to oral cancer pain is investigated in the present study. The findings demonstrate that CGRP-immunoreactive (-ir) neurons and neurites innervate orthotopic oral cancer xenograft tumors in mice. Cancer increases anterograde transport of CGRP in axons innervating the tumor, supporting neurogenic secretion as the source of CGRP in the oral cancer microenvironment. CGRP antagonism reverses oral cancer nociception in preclinical oral cancer pain models. Single-cell RNA-sequencing is used to identify cell types in the cancer microenvironment expressing the CGRP receptor components, receptor activity modifying protein 1 Ramp1 and calcitonin receptor like receptor (CLR, encoded by Calcrl). Ramp1 and Calcrl transcripts are detected in cells expressing marker genes for Schwann cells, endothelial cells, fibroblasts and immune cells. Ramp1 and Calcrl transcripts are more frequently detected in cells expressing fibroblast and immune cell markers. This work identifies CGRP as mediator of oral cancer pain and suggests the antagonism of CGRP to alleviate oral cancer pain.

Functional neuronal circuits promote disease progression in cancer

The molecular and functional contributions of intratumoral nerves to disease remain largely unknown. We localized synaptic markers within tumors suggesting that these nerves form functional connections. Consistent with this, electrophysiological analysis shows that malignancies harbor significantly higher electrical activity than benign disease or normal tissues. We also demonstrate pharmacologic silencing of tumoral electrical activity. Tumors implanted in transgenic animals lacking nociceptor neurons show reduced electrical activity. These data suggest that intratumoral nerves remain functional at the tumor bed. Immunohistochemical staining demonstrates the presence of the neuropeptide, Substance P (SP), within the tumor space. We show that tumor cells express the SP receptor, NK1R, and that ligand/receptor engagement promotes cellular proliferation and migration. Our findings identify a mechanism whereby intratumoral nerves promote cancer progression.

Gel-forming antagonist provides a lasting effect on CGRP-induced vasodilation

Migraine affects ∼15% of the adult population, and the standard treatment includes the use of triptans, ergotamines, and analgesics. Recently, CGRP and its receptor, the CLR/RAMP1 receptor complex, have been targeted for migraine treatment due to their critical roles in mediating migraine headaches. The effort has led to the approval of several anti-CGRP antibodies for chronic migraine treatment. However, many patients still suffer continuous struggles with migraine, perhaps due to the limited ability of anti-CGRP therapeutics to fully reduce CGRP levels or reach target cells. An alternative anti-CGRP strategy may help address the medical need of patients who do not respond to existing therapeutics. By serendipity, we have recently found that several chimeric adrenomedullin/adrenomedullin 2 peptides are potent CLR/RAMP receptor antagonists and self-assemble to form liquid gels. Among these analogs, the ADE651 analog, which potently inhibits CLR/RAMP1 receptor signaling, forms gels at a 6-20% level. Screening of ADE651 variants indicated that residues at the junctional region of this chimeric peptide are important for gaining the gel-forming capability. Gel-formation significantly slowed the passage of ADE651 molecules through Centricon filters. Consistently, subcutaneous injection of ADE651 gel in rats led to the sustained presence of ADE651 in circulation for >1 week. In addition, analysis of vascular blood flow in rat hindlimbs showed ADE651 significantly reduces CGRP-induced vasodilation. Because gel-forming antagonists could have direct and sustained access to target cells, ADE651 and related antagonists for CLR/RAMP receptors may represent promising candidates for targeting CGRP- and/or adrenomedullin-mediated headaches in migraine patients.

Nociceptor neurons affect cancer immunosurveillance

Solid tumours are innervated by nerve fibres that arise from the autonomic and sensory peripheral nervous systems1-5. Whether the neo-innervation of tumours by pain-initiating sensory neurons affects cancer immunosurveillance remains unclear. Here we show that melanoma cells interact with nociceptor neurons, leading to increases in their neurite outgrowth, responsiveness to noxious ligands and neuropeptide release. Calcitonin gene-related peptide (CGRP)-one such nociceptor-produced neuropeptide-directly increases the exhaustion of cytotoxic CD8+ T cells, which limits their capacity to eliminate melanoma. Genetic ablation of the TRPV1 lineage, local pharmacological silencing of nociceptors and antagonism of the CGRP receptor RAMP1 all reduced the exhaustion of tumour-infiltrating leukocytes and decreased the growth of tumours, nearly tripling the survival rate of mice that were inoculated with B16F10 melanoma cells. Conversely, CD8+ T cell exhaustion was rescued in sensory-neuron-depleted mice that were treated with local recombinant CGRP. As compared with wild-type CD8+ T cells, Ramp1-/- CD8+ T cells were protected against exhaustion when co-transplanted into tumour-bearing Rag1-deficient mice. Single-cell RNA sequencing of biopsies from patients with melanoma revealed that intratumoral RAMP1-expressing CD8+ T cells were more exhausted than their RAMP1-negative counterparts, whereas overexpression of RAMP1 correlated with a poorer clinical prognosis. Overall, our results suggest that reducing the release of CGRP from tumour-innervating nociceptors could be a strategy to improve anti-tumour immunity by eliminating the immunomodulatory effects of CGRP on cytotoxic CD8+ T cells.

The impact of tumor immunogenicity on cancer pain phenotype using syngeneic oral cancer mouse models

Head and neck squamous cell carcinoma (HNSCC) patients report severe function-induced pain at the site of the primary tumor. The current hypothesis is that oral cancer pain is initiated and maintained in the cancer microenvironment due to secretion of algogenic mediators from tumor cells and surrounding immune cells that sensitize the primary sensory neurons innervating the tumor. Immunogenicity, which is the ability to induce an adaptive immune response, has been widely studied using cancer cell transplantation experiments. However, oral cancer pain studies have primarily used xenograft transplant models in which human-derived tumor cells are inoculated in an athymic mouse lacking an adaptive immune response; the role of inflammation in oral cancer-induced nociception is still unknown. Using syngeneic oral cancer mouse models, we investigated the impact of tumor cell immunogenicity and growth on orofacial nociceptive behavior and oral cancer-induced sensory neuron plasticity. We found that an aggressive, weakly immunogenic mouse oral cancer cell line, MOC2, induced rapid orofacial nociceptive behavior in both male and female C57Bl/6 mice. Additionally, MOC2 tumor growth invoked a substantial injury response in the trigeminal ganglia as defined by a significant upregulation of injury response marker ATF3 in tongue-innervating trigeminal neurons. In contrast, using a highly immunogenic mouse oral cancer cell line, MOC1, we found a much slower onset of orofacial nociceptive behavior in female C57Bl/6 mice only as well as sex-specific differences in the tumor-associated immune landscape and gene regulation in tongue innervating sensory neurons. Together, these data suggest that cancer-induced nociceptive behavior and sensory neuron plasticity can greatly depend on the immunogenic phenotype of the cancer cell line and the associated immune response.

The multi-molecular mechanisms of tumor-targeted drug resistance in precision medicine

Clinically, cancer drug therapy is still dominated by chemotherapy drugs. Although the emergence of targeted drugs has greatly improved the survival rate of patients with advanced cancer, drug resistance has always been a difficult problem in clinical cancer treatment. At the current level of medicine, most drugs cannot escape the fate of drug resistance. With the emergence and development of gene detection, liquid biopsy ctDNA technology, and single-cell sequencing technology, the molecular mechanism of tumor drug resistance has gradually emerged. Drugs can also be updated in response to drug resistance mechanisms and bring higher survival benefits. The use of new drugs often leads to new mechanisms of resistance. In this review, the multi-molecular mechanisms of drug resistance are introduced, and the overcoming of drug resistance is discussed from the perspective of the tumor microenvironment.