Inflammatory Monocytes Promote Perineural Invasion via CCL2-Mediated Recruitment and Cathepsin B Expression

Nerve-tumor crosstalk in tumor microenvironment: From tumor initiation and progression to clinical implications

The autonomic nerve system (ANS) innervates organs and tissues throughout the body and maintains functional balance among various systems. Further investigations have shown that excessive activation of ANS not only causes disruption of homeostasis, but also may promote tumor formation. In addition, the dynamic interaction between nerve and tumor cells in the tumor microenvironment also regulate tumor progression. On the one hand, nerves are passively invaded by tumor cells, that is, perineural invasion (PNI). On the other hand, compared with normal tissues, tumor tissues are subject to more abundant innervation, and nerves can influence tumor progression through regulating tumor proliferation, metastasis and drug resistance. A large number of studies have shown that nerve-tumor crosstalk, including PNI and innervation, is closely related to the prognosis of patients, and contributes to the formation of cancer pain, which significantly deteriorates the quality of life for patients. These findings suggest that nerve-tumor crosstalk represents a potential target for anti-tumor therapies and the management of cancer pain in the future. In this review, we systematically describe the mechanism by which nerve-tumor crosstalk regulates tumorigenesis and progression.

Immune Cell Migration to Cancer

Immune cell migration is required for the development of an effective and robust immune response. This elegant process is regulated by both cellular and environmental factors, with variables such as immune cell state, anatomical location, and disease state that govern differences in migration patterns. In all cases, a major factor is the expression of cell surface receptors and their cognate ligands. Rapid adaptation to environmental conditions partly depends on intrinsic cellular immune factors that affect a cell's ability to adjust to new environment. In this review, we discuss both myeloid and lymphoid cells and outline key determinants that govern immune cell migration, including molecules required for immune cell adhesion, modes of migration, chemotaxis, and specific chemokine signaling. Furthermore, we summarize tumor-specific elements that contribute to immune cell trafficking to cancer, while also exploring microenvironment factors that can alter these cellular dynamics within the tumor in both a pro and antitumor fashion. Specifically, we highlight the importance of the secretome in these later aspects. This review considers a myriad of factors that impact immune cell trajectory in cancer. We aim to highlight the immunotherapeutic targets that can be harnessed to achieve controlled immune trafficking to and within tumors.

Exosomal lncRNA XIST promotes perineural invasion of pancreatic cancer cells via miR-211-5p/GDNF

Perineural invasion (PNI) is an essential form of tumor metastasis in multiple malignant cancers, such as pancreatic cancer, prostate cancer, and head and neck cancer. Growing evidence has revealed that pancreatic cancer recurrence and neuropathic pain positively correlate with PNI. Therefore, targeting PNI is a proper strategy for pancreatic cancer treatment. Exosomal lncRNA derived from pancreatic cancer cells is an essential component of the tumor microenvironment. However, whether exosomal lncXIST derived from pancreatic cancer cells can promote PNI and its exact mechanism remains to be elucidated. We show that lncXIST mediates nerve-tumor crosstalk via exosomal delivery. Our data reveal that exosomal lncXIST derived from pancreatic cancer cells is delivered to neural cells and promotes their release of glial-cell-line-derived neurotrophic factor (GDNF), essential in facilitating the PNI of pancreatic cancer. Mechanistically, microRNA-211-5p negatively regulates GDNF, and lncXIST serves as a miR-211-5p sponge. The function of exosomes in the dynamic interplay between nerves and cancer is confirmed in both in vivo and in vitro PNI models. Therefore, targeting pancreatic cancer cell-derived exosomal lncXIST may provide clues for a promising approach for developing a new strategy to combat PNI of pancreatic cancer.

Schwann cells in pancreatic cancer: Unraveling their multifaceted roles in tumorigenesis and neural interactions

Pancreatic ductal adenocarcinoma (PDAC), characterized by heightened neural density, presents a challenging prognosis primarily due to perineural invasion. Recognized for their crucial roles in neural support and myelination, Schwann cells (SCs) significantly influence the process of tumorigenesis. This review succinctly outlines the interplay between PDAC and neural systems, positioning SCs as a nexus in the tumor-neural interface. Subsequently, it delves into the cellular origin and influencers of SCs within the pancreatic tumor microenvironment, emphasizing their multifaceted roles in tumor initiation, progression, and modulation of the neural and immune microenvironment. The discussion encompasses potential therapeutic interventions targeting SCs. Lastly, the review underscores pressing issues, advocating for sustained exploration into the diverse contributions of SCs within the intricate landscape of PDAC, with the aim of enhancing our understanding of their involvement in this complex malignancy.

Molecular pathway of pancreatic cancer-associated neuropathic pain

The pancreas is a heterocrine gland that has both exocrine and endocrine parts. Most pancreatic cancer begins in the cells that line the ducts of the pancreas and is called pancreatic ductal adenocarcinoma (PDAC). PDAC is the most encountered pancreatic cancer type. One of the most important characteristic features of PDAC is neuropathy which is primarily due to perineural invasion (PNI). PNI develops tumor microenvironment which includes overexpression of fibroblasts cells, macrophages, as well as angiogenesis which can be responsible for neuropathy pain. In tumor microenvironment inactive fibroblasts are converted into an active form that is cancer-associated fibroblasts (CAFs). Neurotrophins they also increase the level of Substance P, calcitonin gene-related peptide which is also involved in pain. Matrix metalloproteases are the zinc-associated proteases enzymes which activates proinflammatory interleukin-1β into its activated form and are responsible for release and activation of Substance P which is responsible for neuropathic pain by transmitting pain signal via dorsal root ganglion. All the molecules and their role in being responsible for neuropathic pain are described below.

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.

Tumour-associated macrophages and Schwann cells promote perineural invasion via paracrine loop in pancreatic ductal adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is frequently accompanied by perineural invasion (PNI), which is associated with excruciating neuropathic pain and malignant progression. However, the relationship between PNI and tumour stromal cells has not been clarified.

METHODS

The dorsal root ganglia or sciatic nerves nerve model was used to observe the paracrine interaction and the activation effect among Schwann cells, tumour-associated macrophages (TAMs), and pancreatic cancer cells in vitro. Next generation sequencing, enzyme-linked immunosorbent assay and chromatin immunoprecipitation were used to explore the specific paracrine signalling between TAMs and Schwann cells.

RESULTS

We demonstrated that more macrophages were expressed around nerves that have been infiltrated by pancreatic cancer cells compared with normal nerves in murine and human PNI specimens. In addition, high expression of CD68 or GFAP is associated with an increased incidence of PNI and indicates a poor 5-year survival rate in patients with PDAC. Mechanistically, tumour-associated macrophages (TAMs) activate Schwann cells via the bFGF/PI3K/Akt/c-myc/GFAP pathway. Schwann cells secrete IL-33 to recruit macrophages into the perineural milieu and facilitate the M2 pro-tumourigenic polarisation of macrophages.

CONCLUSIONS

Our study demonstrates that the bFGF/IL-33 positive feedback loop between Schwann cells and TAMs is essential in the process of PNI of PDAC. The bFGF/PI3K/Akt/c-myc/GFAP pathway would open potential avenues for targeted therapy of PDAC.

Macrophage heterogeneity and its interactions with stromal cells in tumour microenvironment

Macrophages and tumour stroma cells account for the main cellular components in the tumour microenvironment (TME). Current advancements in single-cell analysis have revolutionized our understanding of macrophage diversity and macrophage-stroma interactions. Accordingly, this review describes new insight into tumour-associated macrophage (TAM) heterogeneity in terms of tumour type, phenotype, metabolism, and spatial distribution and presents the association between these factors and TAM functional states. Meanwhile, we focus on the immunomodulatory feature of TAMs and highlight the tumour-promoting effect of macrophage-tumour stroma interactions in the immunosuppressive TME. Finally, we summarize recent studies investigating macrophage-targeted therapy and discuss their therapeutic potential in improving immunotherapy by alleviating immunosuppression.

Perineural invasion in colorectal cancer: mechanisms of action and clinical relevance

BACKGROUND

In recent years, the significance of the nervous system in the tumor microenvironment has gained increasing attention. The bidirectional communication between nerves and cancer cells plays a critical role in tumor initiation and progression. Perineural invasion (PNI) occurs when tumor cells invade the nerve sheath and/or encircle more than 33% of the nerve circumference. PNI is a common feature in various malignancies and is associated with tumor invasion, metastasis, cancer-related pain, and unfavorable clinical outcomes. The colon and rectum are highly innervated organs, and accumulating studies support PNI as a histopathologic feature of colorectal cancer (CRC). Therefore, it is essential to investigate the role of nerves in CRC and comprehend the mechanisms of PNI to impede tumor progression and improve patient survival.

CONCLUSION

This review elucidates the clinical significance of PNI, summarizes the underlying cellular and molecular mechanisms, introduces various experimental models suitable for studying PNI, and discusses the therapeutic potential of targeting this phenomenon. By delving into the intricate interactions between nerves and tumor cells, we hope this review can provide valuable insights for the future development of CRC treatments.

Tumor microenvironment crosstalk between tumors and the nervous system in pancreatic cancer: Molecular mechanisms and clinical perspectives

Pancreatic ductal adenocarcinoma (PDAC) exhibits the highest incidence of perineural invasion among all solid tumors. The intricate interplay between tumors and the nervous system plays an important role in PDAC tumorigenesis, progression, recurrence, and metastasis. Various clinical symptoms of PDAC, including anorexia and cancer pain, have been linked to aberrant neural activity, while the presence of perineural invasion is a significant prognostic indicator. The use of conventional neuroactive drugs and neurosurgical interventions for PDAC patients is on the rise. An in-depth exploration of tumor-nervous system crosstalk has revealed novel therapeutic strategies for mitigating PDAC progression and effectively relieving symptoms. In this comprehensive review, we elucidate the regulatory functions of tumor-nervous system crosstalk, provide a succinct overview of the relationship between tumor-nervous system dialogue and clinical symptomatology, and deliberate the current research progress and forthcoming avenues of neural therapy for PDAC.

Gene Expression Array Analyses Predict Proto-Oncogene Expression During Perineural Invasion in Pancreatic Ductal Adenocarcinoma

BACKGROUND/AIMS

Pancreatic ductal adenocarcinoma is the tumor type with the highest incidence of perineural invasion. This study tries to identify the differentially expressed genes regulated between pancreatic ductal adenocarcinoma tissues with perineural invasion and without perineural invasion.

MATERIALS AND METHODS

The GSE102238 profile was downloaded. Gene function and pathway analysis were subsequently conducted. A protein-protein interaction network was constructed to search for hub genes. Both univariate Cox analysis and multivariate Cox analysis were calculated to identify prognostic factors. Quantitative real-time polymerase chain reaction (RT-PCR) and overall survival analysis of hub genes were used to verify.

RESULTS

Our study identified 242 differentially expressed genes including 68 upregulated differentially expressed genes and 174 downregulated differentially expressed genes, which were involved in important functions and pathways. Nine relevant core genes using protein-protein interaction analysis as well as nestin (NES)/vascular endothlial growth factor (VEGF) signaling pathway which is highly related to the pathological process of perineural invasion in pancreatic ductal adenocarcinoma were also discovered. The differentiation was identified as an independent prognostic factor (P < .05) after multivariate Cox analysis. Three upregulated genes (JUP, CALM1, and NES) and 6 downregulated genes (EPHA2, ARF1, ORM2, TERT, IL18, and CXCL3) were validated by quantitative RT-PCR and they all had markedly worse overall survival (P < .05).

CONCLUSION

This analysis showed that 9 core genes including JUP, CALM1, NES, EPHA2, ARF1, ORM2, TERT, IL18, and CXCL3, as well as NES/VEGF signaling pathway, have a relationship with the development process of perineural invasion in pancreatic ductal adenocarcinoma. Cox analysis and overall survival analysis suggested differentiation as an independent prognostic factor and key roles for these 9 hub genes in perineural invasion prognosis in pancreatic ductal adenocarcinoma.

Dedifferentiated Schwann cells promote perineural invasion mediated by the PACAP paracrine signalling in cervical cancer

Perineural invasion (PNI) has emerged as a key pathological feature and be considered as a poor prognostic factor in cervical cancer. However, the underlying molecular mechanisms are largely unknown. Here, PNI status of 269 cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) samples were quantified by using whole-slide diagnostic images obtained from The Cancer Genome Atlas. Integrated analyses revealed that PNI was an indicative marker of poorer disease-free survival for CESC patients. Among the differentially expressed genes, ADCYAP1 were identified. Clinical specimens supported that high expression of PACAP (encoded by ADCYAP1) contributed to PNI in CESC. Mechanistically, PACAP, secreted from cervical cancer cells, reversed myelin differentiation of Schwann cells (SCs). Then, dedifferentiated SCs promoted PNI by producing chemokine FGF17 and by degrading extracellular matrix through secretion of Cathepsin S and MMP-12. In conclusion, this study identified PACAP was associated with PNI in cervical cancer and suggested that tumour-derived PACAP reversed myelin differentiation of SCs to aid PNI.

Crosstalk of nervous and immune systems in pancreatic cancer

Pancreatic cancer is a highly malignant tumor known for its extremely low survival rate. The combination of genetic disorders within pancreatic cells and the tumor microenvironment contributes to the emergence and progression of this devastating disease. Extensive research has shed light on the nature of the microenvironmental cells surrounding the pancreatic cancer, including peripheral nerves and immune cells. Peripheral nerves release neuropeptides that directly target pancreatic cancer cells in a paracrine manner, while immune cells play a crucial role in eliminating cancer cells that have not evaded the immune response. Recent studies have revealed the intricate interplay between the nervous and immune systems in homeostatic condition as well as in cancer development. In this review, we aim to summarize the function of nerves in pancreatic cancer, emphasizing the significance to investigate the neural-immune crosstalk during the advancement of this malignant cancer.

Glial cell-derived soluble factors increase the metastatic potential of pancreatic adenocarcinoma cells and induce epithelial-to-mesenchymal transition

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive types of cancer, characterized by the spreading of highly metastatic cancer cells, including invasion into surrounding nerves and perineural spaces. Nerves, in turn, can invade the tumor tissue and, through the secretion of neurotrophic factors, chemokines, and cytokines, contribute to PDAC progression. However, the contribution of the nerve-associated glial cells to PDAC progression is not well characterized.

METHODS

Two murine PDAC cell lines were cultured with the conditioned media (CM) of primary enteric glial cells or IMS32 Schwann cells (SCs). Different properties of PDAC cells, such as invasiveness, migratory capacity, and resistance to gemcitabine, were measured by RT-qPCR, microscopy, and MTT assays. Using a neuronal cell line, the observed effects were confirmed to be specific to the glial lineage.

RESULTS

Compared to the control medium, PDAC cells in the glial cell-conditioned medium showed increased invasiveness and migratory capacity. These cells showed reduced E-cadherin and increased N-cadherin and Vimentin levels, all markers of epithelial-mesenchymal transition (EMT). Primary enteric glial cell CM inhibited the proliferation of PDAC cells but preserved their viability, upregulated transcription factor Snail, and increased their resistance to gemcitabine. The conditioned medium generated from the IMS32 SCs produced comparable results.

CONCLUSION

Our data suggest that glial cells can increase the metastatic potential of PDAC cells by increasing their migratory capacity and inducing epithelial-to-mesenchymal transition, a re-programming that many solid tumors use to undergo metastasis. Glial cell-conditioned medium also increased the chemoresistance of PDAC cells. These findings may have implications for future therapeutic strategies, such as targeting glial cell-derived factor signaling in PDAC.

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.

Unraveling the Mysteries of Perineural Invasion in Benign and Malignant Conditions

Perineural invasion (PNI) is defined as the dissemination of neoplastic cells within the perineural space. PNI can be a strong indicator of malignancy and is linked to poor prognosis and adverse outcomes in various malignant neoplasms; nevertheless, it can also be seen in benign pathologic conditions. In this review article, we discuss various signaling pathways and neurotrophic factors implicated in the development and progression of PNI. We also describe the methodology, benefits, and limitations of different in vitro, ex vivo, and in vivo models of PNI. The spectrum of presentation for PNI can range from diffuse spread within large nerves ("named" nerves) all the way through localized spread into unnamed microscopic nerves. Therefore, the clinical significance of PNI is related to its extent rather than its mere presence or absence. In this article, we discuss the guidelines for the identification and quantification of PNI in different malignant neoplasms based on the College of American Pathologists (CAP) and World Health Organization (WHO) recommendations. We also describe benign pathologic conditions and neoplasms demonstrating PNI and potential mimics of PNI. Finally, we explore avenues for the future development of targeted therapy options via modulation of signaling pathways involved in PNI.

Perineural invasion: A potential driver of cancer-induced pain

Perineural invasion (PNI) is the process through which tumors invade and interact with nerves. The dynamic changes in the nerves caused by PNI may induce disturbing symptoms. PNI-related cancer pain in neuro-rich tumors has attracted much attention because the occurrence of tumor-induced pain is closely related to the invasion of nerves in the tumor microenvironment. PNI-related pain might indicate the occurrence of PNI, guide the improvement of treatment strategies, and predict the unresectability of tumors and the necessity of palliative care. Although many studies have investigated PNI, its relationship with tumor-induced pain and its common mechanisms have not been summarized thoroughly. Therefore, in this review, we evaluated the relationship between PNI and cancer-associated pain. We showed that PNI is a major cause of cancer-related pain and that this pain can predict the occurrence of PNI. We also elucidated the cellular and molecular mechanisms of PNI-induced pain. Finally, we analyzed the possible targets for alleviating PNI-related pain or combined antitumor and pain management. Our findings might provide new perspectives for improving the treatment of patients with malignant tumors.

Genetic association of cardiovascular disease related biomarkers with the overall survival of hepatocellular carcinoma: a Mendelian randomization analysis

Observational studies have reported associations between circulating biomarkers related to cardiovascular disease and the survival of patients with hepatocellular carcinoma. However, the relationship between these biomarkers and survival remains controversial. We conducted a two-sample Mendelian randomization analysis to investigate possible causal associations between cardiovascular disease biomarkers and hepatocellular carcinoma survival. Genetic risk scores, calculated using individual-level data from 866 cases of hepatitis B virus-related hepatocellular carcinoma in Guangxi, were utilized as proxies for four cardiovascular disease biomarkers: C-reactive protein, Apolipoprotein A-1, Cystatin C, and Lipoprotein(a). Associations between the genetic scores and survival were analyzed using Cox regression. The inverse-variance weighted method was used to estimate the summary statistics for the biomarkers and survival. Considering the multiple comparisons, the statistical significance was set at P < 0.0125. We observed a significant risk signal between genetically increased Cystatin C levels and poorer survival in hepatocellular carcinoma (HR for genetic scores = 1.29, 95% CI = 1.02-1.64; HR for inverse-variance weighted = 2.60, 95% CI = 1.45-4.65). Furthermore, we found a causal relationship of genetically determined Cystatin C and Lipoprotein(a) level with the survival of hepatocellular carcinoma patients with embolus. Our findings indicated the causal effects of increased levels of Cystatin C and Lipoprotein(a) on poorer survival in hepatocellular carcinoma.

Predicting response to immunotherapy in gastric cancer via assessing perineural invasion-mediated inflammation in tumor microenvironment

BACKGROUND

The perineural invasion (PNI)-mediated inflammation of the tumor microenvironment (TME) varies among gastric cancer (GC) patients and exhibits a close relationship with prognosis and immunotherapy. Assessing the neuroinflammation of TME is important in predicting the response to immunotherapy in GC patients.

METHODS

Fifteen independent cohorts were enrolled in this study. An inflammatory score was developed and validated in GC. Based on PNI-related prognostic inflammatory signatures, patients were divided into Clusters A and B using unsupervised clustering. The characteristics of clusters and the potential regulatory mechanism of key genes were verified by RT-PCR, western-blot, immunohistochemistry and immunofluorescence in cell and tumor tissue samples.The neuroinflammation infiltration (NII) scoring system was developed based on principal component analysis (PCA) and visualized in a nomogram together with other clinical characteristics.

RESULTS

Inflammatory scores were higher in GC patients with PNI compared with those without PNI (P < 0.001). NII.clusterB patients with PNI had abundant immune cell infiltration in the TME but worse prognosis compared with patients in the NII.clusterA patients with PNI and non-PNI subgroups. Higher immune checkpoint expression was noted in NII.clusterB-PNI. VCAM1 is a specific signature of NII.clusterB-PNI, which regulates PD-L1 expression by affecting the phosphorylation of STAT3 in GC cells. Patients with PNI and high NII scores may benefit from immunotherapy. Patients with low nomogram scores had a better prognosis than those with high nomogram scores.

CONCLUSIONS

Inflammation mediated by PNI is one of the results of tumor-nerve crosstalk, but its impact on the tumor immune microenvironment is complex. Assessing the inflammation features of PNI is a potential method in predicting the response of immunotherapy effectively.

Pancreatic ductal adenocarcinoma induces neural injury that promotes a transcriptomic and functional repair signature by peripheral neuroglia

Perineural invasion (PNI) is the phenomenon whereby cancer cells invade the space surrounding nerves. PNI occurs frequently in epithelial malignancies, but is especially characteristic of pancreatic ductal adenocarcinoma (PDAC). The presence of PNI portends an increased incidence of local recurrence, metastasis and poorer overall survival. While interactions between tumor cells and nerves have been investigated, the etiology and initiating cues for PNI development is not well understood. Here, we used digital spatial profiling to reveal changes in the transcriptome and to allow for a functional analysis of neural-supportive cell types present within the tumor-nerve microenvironment of PDAC during PNI. We found that hypertrophic tumor-associated nerves within PDAC express transcriptomic signals of nerve damage including programmed cell death, Schwann cell proliferation signaling pathways, as well as macrophage clearance of apoptotic cell debris by phagocytosis. Moreover, we identified that neural hypertrophic regions have increased local neuroglial cell proliferation which was tracked using EdU tumor labeling in KPC mice, as well as frequent TUNEL positivity, suggestive of a high turnover rate. Functional calcium imaging studies using human PDAC organotypic slices confirmed nerve bundles had neuronal activity, as well as contained NGFR+ cells with high sustained calcium levels, which are indicative of apoptosis. This study reveals a common gene expression pattern that characterizes solid tumor-induced damage to local nerves. These data provide new insights into the pathobiology of the tumor-nerve microenvironment during PDAC as well as other gastrointestinal cancers.

Application of nano-radiosensitizers in combination cancer therapy

Radiosensitizers are compounds or nanostructures, which can improve the efficiency of ionizing radiation to kill cells. Radiosensitization increases the susceptibility of cancer cells to radiation-induced killing, while simultaneously reducing the potentially damaging effect on the cellular structure and function of the surrounding healthy tissues. Therefore, radiosensitizers are therapeutic agents used to boost the effectiveness of radiation treatment. The complexity and heterogeneity of cancer, and the multifactorial nature of its pathophysiology has led to many approaches to treatment. The effectiveness of each approach has been proven to some extent, but no definitive treatment to eradicate cancer has been discovered. The current review discusses a broad range of nano-radiosensitizers, summarizing possible combinations of radiosensitizing NPs with several other types of cancer therapy options, focusing on the benefits and drawbacks, challenges, and future prospects.

Rapid cancer cell perineural invasion utilizes amoeboid migration

The invasion of nerves by cancer cells, or perineural invasion (PNI), is potentiated by the nerve microenvironment and is associated with adverse clinical outcomes. However, the cancer cell characteristics that enable PNI are poorly defined. Here, we generated cell lines enriched for a rapid neuroinvasive phenotype by serially passaging pancreatic cancer cells in a murine sciatic nerve model of PNI. Cancer cells isolated from the leading edge of nerve invasion showed a progressively increasing nerve invasion velocity with higher passage number. Transcriptome analysis revealed an upregulation of proteins involving the plasma membrane, cell leading edge, and cell movement in the leading neuroinvasive cells. Leading cells progressively became round and blebbed, lost focal adhesions and filipodia, and transitioned from a mesenchymal to amoeboid phenotype. Leading cells acquired an increased ability to migrate through microchannel constrictions and associated more with dorsal root ganglia than nonleading cells. ROCK inhibition reverted leading cells from an amoeboid to mesenchymal phenotype, reduced migration through microchannel constrictions, reduced neurite association, and reduced PNI in a murine sciatic nerve model. Cancer cells with rapid PNI exhibit an amoeboid phenotype, highlighting the plasticity of cancer migration mode in enabling rapid nerve invasion.

Pancreatic Ductal Adenocarcinoma Induces Neural Injury that Promotes a Transcriptomic and Functional Repair Signature by Peripheral Neuroglia

Perineural invasion (PNI) is the phenomenon whereby cancer cells invade the space surrounding nerves. PNI occurs frequently in epithelial malignancies, but is especially characteristic of pancreatic ductal adenocarcinoma (PDAC). The presence of PNI portends an increased incidence of local recurrence, metastasis and poorer overall survival. While interactions between tumor cells and nerves have been investigated, the etiology and initiating cues for PNI development is not well understood. Here, we used digital spatial profiling to reveal changes in the transcriptome and to allow for a functional analysis of neural-supportive cell types present within the tumor-nerve microenvironment of PDAC during PNI. We found that hypertrophic tumor-associated nerves within PDAC express transcriptomic signals of nerve damage including programmed cell death, Schwann cell proliferation signaling pathways, as well as macrophage clearance of apoptotic cell debris by phagocytosis. Moreover, we identified that neural hypertrophic regions have increased local neuroglial cell proliferation which was tracked using EdU tumor labeling in KPC mice. This study reveals a common gene expression pattern that characterizes solid tumor-induced damage to local nerves. These data provide new insights into the pathobiology of the tumor-nerve microenvironment during PDAC as well as other gastrointestinal cancers.

Cancer hallmarks intersect with neuroscience in the tumor microenvironment

The mechanisms underlying the multistep process of tumorigenesis can be distilled into a logical framework involving the acquisition of functional capabilities, the so-called hallmarks of cancer, which are collectively envisaged to be necessary for malignancy. These capabilities, embodied both in transformed cancer cells as well as in the heterotypic accessory cells that together constitute the tumor microenvironment (TME), are conveyed by certain abnormal characteristics of the cancerous phenotype. This perspective discusses the link between the nervous system and the induction of hallmark capabilities, revealing neurons and neuronal projections (axons) as hallmark-inducing constituents of the TME. We also discuss the autocrine and paracrine neuronal regulatory circuits aberrantly activated in cancer cells that may constitute a distinctive "enabling" characteristic contributing to the manifestation of hallmark functions and consequent cancer pathogenesis.

The evolving tumor microenvironment: From cancer initiation to metastatic outgrowth

Cancers represent complex ecosystems comprising tumor cells and a multitude of non-cancerous cells, embedded in an altered extracellular matrix. The tumor microenvironment (TME) includes diverse immune cell types, cancer-associated fibroblasts, endothelial cells, pericytes, and various additional tissue-resident cell types. These host cells were once considered bystanders of tumorigenesis but are now known to play critical roles in the pathogenesis of cancer. The cellular composition and functional state of the TME can differ extensively depending on the organ in which the tumor arises, the intrinsic features of cancer cells, the tumor stage, and patient characteristics. Here, we review the importance of the TME in each stage of cancer progression, from tumor initiation, progression, invasion, and intravasation to metastatic dissemination and outgrowth. Understanding the complex interplay between tumor cell-intrinsic, cell-extrinsic, and systemic mediators of disease progression is critical for the rational development of effective anti-cancer treatments.

Important Cells and Factors from Tumor Microenvironment Participated in Perineural Invasion

Perineural invasion (PNI) as the fourth way for solid tumors metastasis and invasion has attracted a lot of attention, recent research reported a new point that PNI starts to include axon growth and possible nerve "invasion" to tumors as the component. More and more tumor-nerve crosstalk has been explored to explain the internal mechanism for tumor microenvironment (TME) of some types of tumors tends to observe nerve infiltration. As is well known, the interaction of tumor cells, peripheral blood vessels, extracellular matrix, other non-malignant cells, and signal molecules in TME plays a key role in the occurrence, development, and metastasis of cancer, as to the occurrence and development of PNI. We aim to summarize the current theories on the molecular mediators and pathogenesis of PNI, add the latest scientific research progress, and explore the use of single-cell spatial transcriptomics in this invasion way. A better understanding of PNI may help to understand tumor metastasis and recurrence and will be beneficial for improving staging strategies, new treatment methods, and even paradigm shifts in our treatment of patients.

Impact of Perineural Invasion and Preexisting Type 2 Diabetes on Patients with Esophageal Squamous Cell Carcinoma Receiving Neoadjuvant Chemoradiotherapy

Neoadjuvant chemoradiotherapy (neoCRT) followed by surgery is the cornerstone treatment strategy in locally advanced esophageal squamous cell carcinoma (ESCC). Despite this high- intensity multimodality therapy, most patients still experience recurrences and metastases, especially those who do not achieve a pathological complete response (pCR) after neoCRT. Here, we focused on identifying poor prognostic factors. In this retrospective cohort study; we enrolled 140 patients who completed neoCRT plus surgery treatment sequence with no interval metastasis. Overall, 45 of 140 patients (32.1%) achieved a pCR. The overall survival, disease-free survival (DFS), and metastasis-free survival was significantly better in patients with a pCR than in patients with a non-pCR. In the non-pCR subgroup, the presence of perineural invasion (PNI) and preexisting type 2 diabetes (T2DM) were two factors adversely affecting DFS. After adjusting for other factors, multivariate analysis showed that the hazard ratio (HR) was 2.354 (95% confidence interval [CI] 1.240-4.467, p = 0.009) for the presence of PNI and 2.368 (95% CI 1.351-4.150, p = 0.003) for preexisting T2DM. Patients with a combination of both factors had the worst survival. In conclusion, PNI and preexisting T2DM may adversely affect the prognosis of patients with ESCC receiving neoadjuvant chemoradiotherapy.

Reprogrammed Schwann Cells Organize into Dynamic Tracks that Promote Pancreatic Cancer Invasion

Nerves are a component of the tumor microenvironment contributing to cancer progression, but the role of cells from nerves in facilitating cancer invasion remains poorly understood. Here we show that Schwann cells (SC) activated by cancer cells collectively function as tumor-activated Schwann cell tracks (TAST) that promote cancer cell migration and invasion. Nonmyelinating SCs form TASTs and have cell gene expression signatures that correlate with diminished survival in patients with pancreatic ductal adenocarcinoma. In TASTs, dynamic SCs form tracks that serve as cancer pathways and apply forces on cancer cells to enhance cancer motility. These SCs are activated by c-Jun, analogous to their reprogramming during nerve repair. This study reveals a mechanism of cancer cell invasion that co-opts a wound repair process and exploits the ability of SCs to collectively organize into tracks. These findings establish a novel paradigm of how cancer cells spread and reveal therapeutic opportunities.

SIGNIFICANCE

How the tumor microenvironment participates in pancreatic cancer progression is not fully understood. Here, we show that SCs are activated by cancer cells and collectively organize into tracks that dynamically enable cancer invasion in a c-Jun-dependent manner. See related commentary by Amit and Maitra, p. 2240. This article is highlighted in the In This Issue feature, p. 2221.

Perineural invasion-associated biomarkers for tumor development

Perineural invasion (PNI) is the process of neoplastic invasion of peripheral nerves and is considered to be the fifth mode of cancer metastasis. PNI has been detected in head and neck tumors and pancreatic, prostate, bile duct, gastric, and colorectal cancers. It leads to poor prognostic outcomes and high local recurrence rates. Despite the increasing number of studies on PNI, targeted therapeutic modalities have not been proposed. The identification of PNI-related biomarkers would facilitate the non-invasive and early diagnosis of cancers, the establishment of prognostic panels, and the development of targeted therapeutic approaches. In this review, we compile information on the molecular mediators involved in PNI-associated cancers. The expression and prognostic significance of molecular mediators and their receptors in PNI-associated cancers are analyzed, and the possible mechanisms of action of these mediators in PNI are explored, as well as the association of cells in the microenvironment where PNI occurs.

The Role of Schwann Cells in Cancer

Schwann cells (SCs) are the most abundant cell type in the nerves in the peripheral nervous system and compose a family of subtypes that are endowed with a variety of different functions. SCs facilitate the transmission of neural impulses, provide nutrients and protection for neurons, guide axons in nerve repair, and regulate immune functions. In the context of cancer, recent studies have revealed an active role of SCs in promoting cancer cell invasion, modulating immune responses, and transmitting pain sensation.

Activation of STING in the pancreatic tumor microenvironment: A novel therapeutic opportunity

Pancreatic ductal adenocarcinoma (PDAC) is a cancer of poor prognosis that presents with a dense desmoplastic stroma that contributes to therapeutic failure. PDAC patients are mostly unresponsive to immunotherapy. However, hopes to elicit response to immunotherapy have emerged with novel strategies targeting the Stimulator of Interferon Genes (STING) protein, which is a major regulator of tumor-associated inflammation. Combination of STING agonists with conventional immunotherapy approaches has proven to potentiate therapeutic benefits in several cancers. However, recent data underscore that the output of STING activation varies depending on the cellular and tissue context. This suggests that tumor heterogeneity, and in particular the heterogeneity of the tumor microenvironment (TME), is a key factor determining whether STING activation would bear benefits for patients. In this review, we discuss the potential benefits of STING activation in PDAC. To this aim, we describe the major components of the PDAC TME, and the expected consequences of STING activation.

The Role of Extracellular Vesicles in Cancer-Nerve Crosstalk of the Peripheral Nervous System

Although the pathogenic operations of cancer–nerve crosstalk (e.g., neuritogenesis, neoneurogensis, and perineural invasion—PNI) in the peripheral nervous system (PNS) during tumorigenesis, as well as the progression of all cancer types is continuing to emerge as an area of unique scientific interest and study, extensive, wide-ranging, and multidisciplinary investigations still remain fragmented and unsystematic. This is especially so in regard to the roles played by extracellular vesicles (EVs), which are lipid bilayer-enclosed nano- to microsized particles that carry multiple-function molecular cargos, facilitate intercellular communication in diverse processes. Accordingly, the biological significance of EVs has been greatly elevated in recent years, as there is strong evidence that they could contribute to important and possibly groundbreaking diagnostic and therapeutic innovations. This can be achieved and the pace of discoveries accelerated through cross-pollination from existing knowledge and studies regarding nervous system physiology and pathology, as well as thoroughgoing collaborations between oncologists, neurobiologists, pathologists, clinicians, and researchers. This article offers an overview of current and recent past investigations on the roles of EVs in cancer–nerve crosstalk, as well as in neural development, physiology, inflammation, injury, and regeneration in the PNS. By highlighting the mechanisms involved in physiological and noncancerous pathological cellular crosstalk, we provide hints that may inspire additional translational studies on cancer–nerve interplay.

Emerging experimental models for assessing perineural invasion in human cancers

Cancer neuroscience has emerged as a burgeoning field for the investigation of cancer-nervous system interactions. Perineural invasion (PNI) is defined as the presence of cancer cells that surround and/or invade the nerves infiltrating the tumor microenvironment. PNI is closely associated with increased tumor recurrence and diminished survival in many cancer types. Based on diverse in vitro, ex vivo, and in vivo models, mounting evidence suggests that the reciprocal crosstalk between nerves and cancer cells drives PNI, which is mediated by several factors including secreted neurotrophins, chemokines, exosomes, and inflammatory cells. Typical in vitro models using dorsal root ganglia (DRG) cells cocultured with cancer cells or other cell types allow the study of isolated factors. Ex vivo PNI models created by cocultivating cancer cells with explanted vagus and sciatic nerves enable the study of neuroaffinity in a time-saving and cost-efficient manner. In vivo models such as genetically engineered mouse models (GEMMs) and the chicken embryo chorioallantoic membrane (CAM)-DRG model, provide the nerve microenvironment needed to recapitulate the complex pathophysiological processes of PNI. Here, we summarize the current methods commonly used for modeling PNI and discuss the inherent pros and cons of these approaches for understanding PNI biology.

Schwann Cells in Digestive System Disorders

Proper functioning of the digestive system is ensured by coordinated action of the central and peripheral nervous systems (PNS). Peripheral innervation of the digestive system can be viewed as intrinsic and extrinsic. The intrinsic portion is mainly composed of the neurons and glia of the enteric nervous system (ENS), while the extrinsic part is formed by sympathetic, parasympathetic, and sensory branches of the PNS. Glial cells are a crucial component of digestive tract innervation, and a great deal of research evidence highlights the important status of ENS glia in health and disease. In this review, we shift the focus a bit and discuss the functions of Schwann cells (SCs), the glial cells of the extrinsic innervation of the digestive system. For more context, we also provide information on the basic findings regarding the function of innervation in disorders of the digestive organs. We find diverse SC roles described particularly in the mouth, the pancreas, and the intestine. We note that most of the scientific evidence concerns the involvement of SCs in cancer progression and pain, but some research identifies stem cell functions and potential for regenerative medicine.

Schwann Cells in the Tumor Microenvironment: Need More Attention

The tumor microenvironment (TME), which is composed of various cell components and signaling molecules, plays an important role in the occurrence and progression of tumors and has become the central issue of current cancer research. In recent years, as a part of the TME, the peripheral nervous system (PNS) has attracted increasing attention. Moreover, emerging evidence shows that Schwann cells (SCs), which are the most important glial cells in the PNS, are not simply spectators in the TME. In this review article, we focused on the up-to-date research progress on SCs in the TME and introduced our point of view. In detail, we described that under two main tumor-nerve interaction patterns, perineural invasion (PNI) and tumor innervation, SCs were reprogrammed and acted as important participants. We also investigated the newest mechanisms between the interactions of SCs and tumor cells. In addition, SCs can have profound impacts on other cellular components in the TME, such as immune cells and cancer-associated fibroblasts (CAFs), involving immune regulation, tumor-related pain, and nerve remodeling. Overall, these innovative statements can expand the scope of the TME, help fully understand the significant role of SCs in the tumor-nerve-immune axis, and propose enlightenments to innovate antitumor therapeutic methods and future research.

Diffuse pattern, orbital invasion, perineural invasion and Ki-67 are associated with nodal metastasis in patients with eyelid sebaceous carcinoma

Background

Metastasis dominates the prognosis of eyelid sebaceous carcinoma (SC). This study aimed to explore risk factors for nodal metastasis and develop a nomogram to predict nodal metastasis in patients with eyelid SC.

Methods

A retrospective case–control study was performed, comprising 320 patients with eyelid SC. Cox analyses were employed to investigate predictors of metastasis-free survival (MFS), and a nomogram was established and validated by the bootstrap method.

Results

Forty patients (12.5%) developed nodal metastasis during a median follow-up of 48.0 months, and the median period between the initial treatment and first nodal metastasis was 18.5 months (range 6.0–80.0 months). The 1-year, 3-year and 5-year nodal metastasis rates were 5.5%, 12.5% and 15.4%, respectively. Diffuse pattern (HR: 4.34, 95% CI 1.75 to 10.76, p=0.002), orbital invasion at presentation (HR: 3.22, 95% CI 1.42 to 7.33, p=0.005), perineural invasion (HR: 3.24, 95% CI 1.11 to 9.49, p=0.032) and high Ki-67 percentage (HR: 1.03, 95% CI 1.01 to 1.05, p<0.001) were identified as independent risk factors for nodal metastasis. A nomogram that integrated these four factors had a C-index of 0.785, demonstrating a strong power in predicting nodal metastasis of eyelid SC.

Conclusions

We identified risk factors for nodal metastasis and developed a nomogram to provide individualised estimates of nodal metastasis for eyelid SC patients and guide postoperative management. This nomogram contained clinicopathological factors besides the T category of the TNM staging system and suggesting great clinical value.

MCP-1 targeting: Shutting off an engine for tumor development

A large amount of research has proven that monocyte chemotactic protein-1 (MCP-1) is associated with different types of disease, including autoimmune, metabolic and cardiovascular diseases. In addition, several studies have found that MCP-1 is associated with tumor development. MCP-1 expression level in the tumor microenvironment is associated with tumor development, including in tumor invasion and metastasis, angiogenesis, and immune cell infiltration. However, the precise mechanism involved is currently being investigated. MCP-1 exerts its effects mainly via the MCP-1/C-C motif chemokine receptor 2 axis and leads to the activation of classical signaling pathways, such as PI3K/Akt/mTOR, ERK/GSK-3β/Snail, c-Raf/MEK/ERK and MAPK in different cells. The specific mechanism is still under debate; however, target therapy utilizing MCP-1 as a neutralizing antibody has been found to have a detrimental effect on tumor development. The aim of the present review was to examine the effect of MCP-1 on tumor development from several aspects, including its structure, its involvement in signaling pathways, the participating cells, and the therapeutic agents targeting MCP-1. The improved understanding into the structure of MCP-1 and the mechanism of action may facilitate new and practical therapeutic agents to achieve maximum performance in the treatment of patients with cancer.

CD47 blockade enhances the efficacy of intratumoral STING-targeting therapy by activating phagocytes

Activation of STING signaling plays an important role in anti-tumor immunity, and we previously reported the anti-tumor effects of STING through accumulation of M1-like macrophages in tumor tissue treated with a STING agonist. However, myeloid cells express SIRPα, an inhibitory receptor for phagocytosis, and its receptor, CD47, is overexpressed in various cancer types. Based on our findings that breast cancer patients with highly expressed CD47 have poor survival, we evaluated the therapeutic efficacy and underlying mechanisms of combination therapy with the STING ligand cGAMP and an antagonistic anti-CD47 mAb using E0771 mouse breast cancer cells. Anti-CD47 mAb monotherapy did not suppress tumor growth in our setting, whereas cGAMP and anti-CD47 mAb combination therapy inhibited tumor growth. The combination therapy enhanced phagocytosis of tumor cells and induced systemic anti-tumor immune responses, which rely on STING and type I IFN signaling. Taken together, our findings indicate that coadministration of cGAMP and an antagonistic anti-CD47 mAb may be promising for effective cancer immunotherapy.

Clearance of peripheral nerve misfolded mutant protein by infiltrated macrophages correlates with motor neuron disease progression

Macrophages expressing C-C chemokine receptor type 2 (CCR2) infiltrate the central and peripheral neural tissues of amyotrophic lateral sclerosis (ALS) patients. To identify the functional role of CCR2⁺ macrophages in the pathomechanisms of ALS, we used an ALS animal model, mutant Cu/Zn superoxide dismutase 1^G93A (mSOD1)-transgenic (Tg) mice. To clarify the CCR2 function in the model, we generated SOD1^G93A/CCR2^{Red fluorescence protein (RFP)/Wild type (WT)}/CX3CR1^{Green fluorescence protein (GFP)/WT}-Tg mice, which heterozygously express CCR2-RFP and CX3CR1-GFP, and SOD1^G93A/CCR2^RFP/RFP-Tg mice, which lack CCR2 protein expression and present with a CCR2-deficient phenotype. In mSOD1-Tg mice, mSOD1 accumulated in the sciatic nerve earlier than in the spinal cord. Furthermore, spinal cords of SOD1^G93A/CCR2^RFP/WT/CX3CR1^GFP/WT mice showed peripheral macrophage infiltration that emerged at the end-stage, whereas in peripheral nerves, macrophage infiltration started from the pre-symptomatic stage. Before disease onset, CCR2⁺ macrophages harboring mSOD1 infiltrated sciatic nerves earlier than the lumbar cord. CCR2-deficient mSOD1-Tg mice showed an earlier onset and axonal derangement in the sciatic nerve than CCR2-positive mSOD1-Tg mice. CCR2-deficient mSOD1-Tg mice showed an increase in deposited mSOD1 in the sciatic nerve compared with CCR2-positive mice. These findings suggest that CCR2⁺ and CX3CR1⁺ macrophages exert neuroprotective functions in mSOD1 ALS via mSOD1 clearance from the peripheral nerves.

Prognostic Signature of Osteosarcoma Based on 14 Autophagy-Related Genes

Background: Osteosarcoma is a common malignancy of bone with inferior survival outcome. Autophagy can exert multifactorial influence on tumorigenesis and tumor progression. However, the specific function of genes related to autophagy in the prognosis of osteosarcoma patients remains unclear. Herein, we aimed to explore the association of genes related to autophagy with the survival outcome of osteosarcoma patients.

Methods: The autophagy-associated genes that were related to the prognosis of osteosarcoma were optimized by LASSO Cox regression analysis. The survival of osteosarcoma patients was forecasted by multivariate Cox regression analysis. The immune infiltration status of 22 immune cell types in osteosarcoma patients with high and low risk scores was compared by using the CIBERSORT tool.

Results: The risk score model constructed according to 14 autophagy-related genes (ATG4A, BAK1, BNIP3, CALCOCO2, CCL2, DAPK1, EGFR, FAS, GRID2, ITGA3, MYC, RAB33B, USP10, and WIPI1) could effectively predict the prognosis of patients with osteosarcoma. A nomogram model was established based on risk score and metastasis.

Conclusion: Autophagy-related genes were identified as pivotal prognostic signatures, which could guide the clinical decision making in the treatment of osteosarcoma.

Cellular and molecular mechanisms of perineural invasion of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignant disease with a unique tumor microenvironment surrounded by an interlaced network of cancer and noncancerous cells. Recent works have revealed that the dynamic interaction between cancer cells and neuronal cells leads to perineural invasion (PNI), a clinical pathological feature of PDAC. The formation and function of PNI are dually regulated by molecular (e.g., involving neurotrophins, cytokines, chemokines, and neurotransmitters), metabolic (e.g., serine metabolism), and cellular mechanisms (e.g., involving Schwann cells, stromal cells, T cells, and macrophages). Such integrated mechanisms of PNI not only support tumor development, growth, invasion, and metastasis but also mediate the formation of pain, all of which are closely related to poor disease prognosis in PDAC. This review details the modulation, signaling pathways, detection, and clinical relevance of PNI and highlights the opportunities for further exploration that may benefit PDAC patients.

Early maternal separation enhances melanoma progression in adult female mice by immune mechanisms

Maternal separation (MS) is a risk factor for major depressive disorder. Both cancer and depression seem to share a common biological link. Here, we evaluated the progression of melanoma and the underlying mechanisms related to this progression, namely cell proliferation and apoptosis, in adult female mice exposed to MS. Female C57BL/6 mice were exposed to MS for 60 min/day during the first 2 postnatal weeks (here called MS mice) or left undisturbed (here called non-MS mice). Melanoma cells were inoculated subcutaneously into the axillary region of adult animals, and tumor progression was evaluated for 25 days. Adult MS mice presented depressive-like behavior and working memory deficits. MS accelerated murine melanoma growth by mechanisms related to decreased apoptosis and increased cell proliferation rate, such as increased expression of IL-6 and mTOR. MS stimulated eukaryotic elongation factor 2 expression and increased the number of circulating monocytes and DNA damage in peripheral blood leukocytes, an effect associated with oxidative DNA damage. In conclusion, MS accelerated the progression of murine melanoma by mechanisms related to tumor proliferation and apoptosis, revealing a relationship between adverse childhood experiences and cancer progression, particularly melanoma.

Asparagine Synthetase-Mediated l-Asparagine Metabolism Disorder Promotes the Perineural Invasion of Oral Squamous Cell Carcinoma

Dysregulated amino acids metabolism reciprocally interplays with evolutionary phenotypic characteristics of cancer cells to enhance metastasis. The high metastasis potential of oral squamous cell carcinoma (OSCC) can manifest with perineural invasion (PNI). We here aimed to determine the role of amino acids metabolism in OSCCs with different PNI statuses. Targeted metabolomics was used to quantify 48 amino acids in 20 fresh OSCC samples and 25 amino acids were successfully detected, within which 9 were significantly up-regulated in PNI positive (PNI+) samples. As its highest area under the curve value (0.9063), l-asparagine was selected as the biomarker to distinguish PNI+ from PNI negative (PNI-). Then, the key enzyme of l-asparagine, asparagine synthetase (ASNS), was investigated using immunohistochemistry with 86 OSCC patients. The results showed that ASNS mainly expressed in tumor epitheliums and positively correlated with lymph node metastasis and PNI. Moreover, subgroup survival analysis revealed that ASNS expression combined with PNI status significantly improved their prognostic value, which was confirmed by the TCGA OSCC cohort (n = 279). To validate whether ASNS promotes PNI, we determined ASNS expression levels in five OSCC cell lines and one normal oral keratinocyte, and HSC3 showed the lowest ASNS level but CAL33 had the highest. Therefore, HSC3 and CAL33 (or PBS as control) were selected and injected separately into sciatic nerves to construct the in vivo PNI mouse models. Although both models eventually developed the hind-limb paralysis, nerve dysfunction in the CAL33 model progressed significantly earlier than HSC3 (Day 9 vs. Day 24). Besides, CAL33 migrated significantly farther than HSC3 in the nerve microenvironment (P = 0.0003), indicating high ASNS expression is indispensable for OSCC progression, especially PNI formation, through l-asparagine metabolism alteration. This study provides novel insights into how amino acids metabolism disorders alter tumor neurotropism which helps cancer metastasis.

Basal myokine levels are associated with quality of life and depressed mood in older adults

In an aging society, late-life depression has become an increasing problem. There is evidence that physical activity ameliorates depressive symptoms and increases the quality of life (QoL). However, the underlying mechanisms are still poorly understood. Myokines are molecules secreted in response to muscle contraction. Some of them can cross the blood-brain barrier, making them promising candidates for mediating the beneficial effects of physical activity on mood. The present study aims to compare circulating myokine levels to depression/QoL in older athletes and controls. 55 athletes, 57 controls >59 years were enrolled. The assessment included ergometry, magnetic resonance imaging, blood withdrawal, and neuropsychological testing. Serum interleukin-6 (IL-6), irisin, brain-derived neurotrophic factor (BDNF), kynurenine, and cathepsin B were analyzed and compared to surrogates of depression and quality of life. Athletes presented with higher levels of Cathepsin B. Among controls, all myokines but irisin were associated with age. Also, among controls, kynurenine and IL-6 correlated inversely with specific dimensions of quality of life questionnaires, and IL-6 further with depressive symptoms and decreased physical performance. No such associations could be found among athletes. Irisin levels were inversely associated with mild depression and low-grade white matter-lesions in the brain and predicted impaired QoL. The circulating levels of several myokines/muscle activity-related factors appear to be associated with depressive symptoms and impaired QoL among older adults. However, in athletes, some of these connections seem ameliorated, suggesting additional stressors (as f.e. age) or a different pathomechanism among athletes.

Perineural invasion in head and neck squamous cell carcinoma: background, mechanisms, and prognostic implications

PURPOSE OF REVIEW

Perineural invasion (PNI) is a pathological feature frequently observed in head and neck squamous cell carcinoma (HNSCC). The difficulties of pathological standardization and the lack of a simple validated experimental model to study PNI render its analysis complex. Here, we aim to summarize the recent advances in the understanding of the biology of PNI in HNSCC and their potential clinical implications.

RECENT FINDINGS

PNI is a multistep process leading to a dialogue between cancer cells and nerve fibers in HNSCC. Recent studies have identified some of the active molecular mechanisms involved in PNI. Comprehensive studies addressing the transcriptional regulation of PNI bring interesting perspectives for a standardized molecular diagnosis of PNI and a better assessment of its contribution to the aggressiveness of HNSCC.

SUMMARY

Perineural invasion is a complex process that reflects specific tumor biology. In addition to unveiling new fundamental concepts about the tumor microenvironment, research on PNI promises to identify new biomarkers, enabling progress in therapeutic development against HNSCC.

Lack of association between angiotensin-converting enzyme inhibitors and angiotensin receptor blockers and pain improvement in patients with oral cancer

Background

There is a growing body of literature implicating angiotensin II in the modulation of tumour-associated inflammation and pain. However, the impact of angiotensin-converting enzyme inhibitors (ACEis) and angiotensin II receptor blockers (ARBs) on pain and inflammation has not yet been studied in oral cancers. The objective is to investigate the role of ACEi and ARB pharmacotherapy on preoperative pain and inflammatory biomarkers, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and monocyte-to-lymphocyte ratio (MLR), in patients with oral cancer.

Methods

We performed a retrospective study on patients who underwent oral cancer surgery. The Wilcoxon rank-sum test or Kruskal-Wallis analysis was used to evaluate differences in demographic, tumour-related and preoperative characteristics and amongst patients using ARBs, ACEis and no treatment. Multivariable analysis was fitted to estimate the effects of important covariates on severe preoperative pain.

Results

A total of 162 patients with oral malignancies were included in the study. After adjusting for significant covariates, patients with perineural invasion were found to have higher levels of pain (p = 0.0278). Similarly, patients taking ARBs were found to have lower levels of perineural invasion (p = 0.035). The analysis did not demonstrate a significant difference in pain levels when comparing ARBs or ACEis to the no treatment group (p = 0.250). Furthermore, the use of ARB or ACEi did not significantly alter preoperative NLR (p = 0.701) or MLR (p = 0.869).

Conclusions

When compared to no treatment, ARBs and ACEis are not associated with significant analgesic effect or decreased inflammatory scores (NLR, PLR and MLR).

Perineural Invasion in Adenoid Cystic Carcinoma of the Salivary Glands: Where We Are and Where We Need to Go

Adenoid cystic carcinoma of the salivary gland (SACC) is a rare malignant tumors of the head and neck region, but it is one of the most common malignant tumors that are prone to perineural invasion (PNI) of the head and neck. The prognosis of patients with SACC is strongly associated with the presence of perineural spread (PNS). Although many contributing factors have been reported, the mechanisms underlying the preferential destruction of the blood-nerve barrier (BNB) by tumors and the infiltration of the tumor microenvironment by nerve fibers in SACC, have received little research attention. This review summarizes the current knowledge concerning the characteristics of SACC in relation to the PNI, and then highlights the interplay between components of the tumor microenvironment and perineural niche, as well as their contributions to the PNI. Finally, we provide new insights into the possible mechanisms underlying the pathogenesis of PNI, with particular emphasis on the role of extracellular vesicles that may serve as an attractive entry point in future studies.

Microenvironmental Determinants of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) belongs to the most lethal solid tumors in humans. A histological hallmark feature of PDAC is the pronounced tumor microenvironment (TME) that dynamically evolves during tumor progression. The TME consists of different non-neoplastic cells such as cancer-associated fibroblasts, immune cells, endothelial cells, and neurons. Furthermore, abundant extracellular matrix components such as collagen and hyaluronic acid as well as matricellular proteins create a highly dynamic and hypovascular TME with multiple biochemical and physical interactions among the various cellular and acellular components that promote tumor progression and therapeutic resistance. In recent years, intensive research efforts have resulted in a significantly improved understanding of the biology and pathophysiology of the TME in PDAC, and novel stroma-targeted approaches are emerging that may help to improve the devastating prognosis of PDAC patients. However, none of anti-stromal therapies has been approved in patients so far, and there is still a large discrepancy between multiple successful preclinical results and subsequent failure in clinical trials. Furthermore, recent findings suggest that parts of the TME may also possess tumor-restraining properties rendering tailored therapies even more challenging.

Neural invasion: a scenic trail for the nervous tumor and hidden therapeutic opportunity

Neural invasion (NI) is the invasion of cancer cells into nerves, influencing the pathological characteristics of malignant tumors. NI promotes metastasis and is associated with reduced survival of affected patients. Although known for decades, its prognostic and therapeutic implications have not been not much appreciated due to the scattered information available on its clinical complications. The use of multiple nomenclatures to describe NI also generated confusions among researchers to understand this pathological process. Here, we discuss the multiple classifications of NI and review its clinical complications. Recent findings of the regulatory roles of nerves on tumor growth have fuelled research in this field, and there has been several attempts to molecularly define the NI interface and the cancer cells involved. Therefore, in this review, we discuss the large datasets available to characterize the cancer cells in NI and also discuss the roles of Schwann cells and macrophages participating in NI.