Signaling in the microenvironment of pancreatic cancer: Transmitting along the nerve

CCL2/CCR2 axis promotes perineural invasion of salivary adenoid cystic carcinoma via ITGβ5-mediated nerve-tumor interaction

Perineural invasion (PNI) is a notorious feature of salivary adenoid cystic carcinoma (SACC) and other neurotropic tumors. The pathogenesis of PNI that involves the molecular communication between the tumor and the suffered nerve is elusive. The in vitro co-culture assays of SACC cells with dorsal root ganglia (DRG) or neural cells showed that nerve-derived CCL2 activated CCR2 expression in SACC cells, promoting the proliferation, adhesion, migration, and invasion of SACC cells via the ERK1/2/ITGβ5 pathway. Meanwhile, SACC-derived exosomes delivered ITGβ5 to promote the neurite outgrowth of neural cells or DRG. Blocking of CCL2/CCR2 axis or ITGβ5 inhibited the PNI of SACC cells in models in vitro by 3D co-culture of DRG with SACC cells and in vivo by xenografting SACC cells onto the murine sciatic nerve. High levels of ITGβ5 in tissues or plasma exosomes were significantly correlated with CCL2 and CCR2 expression in the tissues and associated with PNI and poor prognosis of SACC cases. Our findings revealed a novel reciprocal loop between neural and tumor cells driven by the CCL2/CCR2 axis and exosomal ITGβ5 during PNI of SACC. The present study may provide a prospective diagnostic and anti-PNI treatment strategy for SACC patients via targeting the nerve-tumor interactions.

GDNF-induced phosphorylation of MUC21 promotes pancreatic cancer perineural invasion and metastasis by activating RAC2 GTPase

Perineural invasion (PNI) is an adverse prognostic feature of pancreatic ductal adenocarcinoma (PDAC). However, the understanding of the interactions between tumors and neural signaling within the tumor microenvironment is limited. In the present study, we found that MUC21 servers as an independent risk factor for poor prognosis in PDAC. Furthermore, we demonstrated that MUC21 promoted the metastasis and PNI of PDAC cells by activating JNK and inducing epithelial-mesenchymal transition (EMT). Mechanistically, glial cell-derived neurotrophic factor, secreted by Schwann cells, phosphorylates the intracellular domain S543 of MUC21 via CDK1 in PDAC cells, facilitating the interaction between MUC21 and RAC2. This interaction leads to membrane anchoring and activation of RAC2, which in turn activates the JNK/ZEB1/EMT axis, ultimately enhancing the metastasis and PNI of PDAC cells. Our results present a novel mechanism of PNI, suggesting that MUC21 is a potential prognostic marker and therapeutic target for PDAC.

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.

Neuron-derived neurotensin promotes pancreatic cancer invasiveness and gemcitabine resistance via the NTSR1/Akt pathway

Perineural invasion and neurogenesis are frequently observed in pancreatic ductal adenocarcinoma (PDAC) and link to poor outcome. However, how neural factors affect PDAC prognosis and the underlying mechanism as well as counteracting therapeutic are still unclear. In silico systematic analysis was performed with PROGgene to identify potential neural factor and its receptor in pancreatic cancer. In vitro assays including migration, invasion, 3D recruitment, and gemcitabine resistance were performed to study the effect of neuron-derived neurotensin (NTS) on pancreatic cancer behavior. Orthotopic animal study was used to validate the in vitro findings. Gene set enrichment analysis (GSEA) was performed to confirm the results from in silico to in vivo. Expression of NTS and its receptor 1 (NTSR1) predicted poor prognosis in PDAC. NTS synthetic peptide or neuron-derived condition medium promoted pancreatic cancer invasiveness and recruitment in 2D and 3D assays. NTS-induced effects depended on NTSR1 and PI3K activation. GDC-0941, a clinically approved PI3K inhibitor, counteracted NTS-induced effects in vitro. Inhibition of NTSR1 in pancreatic cancer cells resulted in decreased tumor dissemination and diminished PI3K activation in vivo. NTS boosted gemcitabine resistance via NTSR1 in pancreatic cancer. Our results suggest that neural cell-secreted NTS plays an important role in promoting PDAC.

Downregulation of miR-503-5p Promotes the Development of Pancreatic Cancer by Targeting Cyclin E2

This study aimed to elucidate the role of microRNA-503 (miR-503) in pancreatic cancer (PC) progression and the underlying regulatory mechanisms. We acquired miR-503-3p and miR-503-5p expression data along with survival times of PC and normal samples from the UCSC Xena database. Using the t-test, we compared the expression of miR-503-3p and miR-503-5p between PC and normal samples, and evaluated their prognostic significance via Kaplan-Meier survival analysis. The expression of miR-503-5p in PC cells was detected by quantitative PCR. We subsequently overexpressed miR-503-5p in PC cells and examined cell viability, apoptosis, and migration through CCK8 assay, flow cytometry, and Transwell assay, respectively. Potential functional targets were identified using miRTarBase and validated by dual-luciferase reporter assay. Both miR-503-3p and miR-503-5p expression were found to be downregulated in PC; however, only miR-503-5p was linked to cancer prognosis based on public data. In vitro experiments demonstrated that overexpression of miR-503-5p substantially decreased cell viability, induced apoptosis, caused G0/G1 arrest, and inhibited cell migration. miR-503-5p was found to target cyclin E2 (CCNE2), and overexpression of CCNE2 could counteract the effects of miR-503-5p on PC cells. Conclusion: The downregulation of miR-503-5p enhances the progression of PC by targeting CCNE2. The detection of miR-503-5p expression may provide valuable insights for the prevention and prognostic evaluation of PC.

Mechanism and application of β-adrenoceptor blockers in soft tissue wound healing

Soft tissue damage stimulates sympathetic nerves to release large amounts of catecholamine hormones which bind to β-adrenergic receptors (β-ARs) on the cell membrane surface. It activates the downstream effector molecules and impairs soft tissue wound healing. β-blockers specifically inhibit β-ARs activation in acute/chronic skin lesions and ulcerative hemangiomas. They also accelerate soft tissue wound healing by shortening the duration of inflammation, speeding keratinocyte migration and reepithelialization, promoting wound contraction and angiogenesis, and inhibiting bacterial virulence effects. In addition, β-blockers shorten wound healing periods in patients with severe thermal damage by reducing the hypermetabolic response. While β-blockers promote/inhibit corneal epithelial cell regeneration and restores limbal stem/progenitor cells function, it could well accelerate/delay corneal wound healing. Given these meaningful effects, a growing number of studies are focused on examining the efficacy and safety of β-blockers in soft tissue wound repair, including acute and chronic wounds, severe thermal damage, ulcerated infantile hemangioma, corneal wounds, and other soft tissue disorders. However, an intensive investigation on their acting mechanisms is imperatively needed. The purpose of this article is to summerize the roles of β-blockers in soft tissue wound healing and explore their clinical applications.

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.

Research Progress of Neural Invasion in Pancreatic Cancer

Pancreatic cancer is one of the highly malignant gastrointestinal tumors in humans, and patients suffer from cancer pain in the process of cancer. Most patients suffer from severe pain in the later stages of the disease. The latest studies have shown that the main cause of pain in patients with pancreatic cancer is neuroinflammation caused by tumor cells invading nerves and triggering neuropathic pain on this basis, which is believed to be the result of nerve invasion. Peripheral nerve invasion (PNI), defined as the presence of cancer cells along the nerve or in the epineurial, perineural, and endoneurial spaces of the nerve sheath, is a special way for cancer to spread to distant sites. However, due to limited clinical materials, the research on the mechanism of pancreatic cancer nerve invasion has not been carried out in depth. In addition, perineural invasion is considered to be one of the underlying causes of recurrence and metastasis after pancreatectomy and an independent predictor of prognosis. This article systematically reviewed the neural invasion of pancreatic cancer through bioinformatics analysis, clinical manifestations and literature reviews.

Tumor- and Nerve-Derived Axon Guidance Molecule Promotes Pancreatic Ductal Adenocarcinoma Progression and Metastasis through Macrophage Reprogramming

Axon guidance molecules were found to be the gene family most frequently altered in pancreatic ductal adenocarcinoma (PDA) through mutations and copy number changes. However, the exact molecular mechanism regarding PDA development remained unclear. Using genetically engineered mouse models to examine one of the axon guidance molecules, semaphorin 3D (SEMA3D), we found a dual role for tumor-derived SEMA3D in malignant transformation of pancreatic epithelial cells and a role for nerve-derived SEMA3D in PDA development. This was demonstrated by the pancreatic-specific knockout of the SEMA3D gene from the KRAS G12D and TP53 R 172 H mutation knock-in, PDX1-Cre (KPC) mouse model which demonstrated a delayed tumor initiation and growth comparing to the original KPC mouse model. Our results showed that SEMA3D knockout skews the macrophages in the pancreas away from M2 polarization, providing a potential mechanistic role of tumor-derived SEMA3D in PDA development. The KPC mice with the SEMA3D knockout remained metastasis-free, however, died from primary tumor growth. We then tested the hypothesis that a potential compensation mechanism could result from SEMA3D which is naturally expressed by the intratumoral nerves. Our study further revealed that nerve-derived SEMA3D does not reprogram macrophages directly, but reprograms macrophages indirectly through ARF6 signaling and lactate production in PDA tumor cells. SEMA3D increases tumor-secreted lactate which is sensed by GPCR132 on macrophages and subsequently stimulates pro-tumorigenic M2 polarization in vivo. Tumor intrinsic- and extrinsic-SEMA3D induced ARF6 signaling through its receptor Plexin D1 in a mutant KRAS-dependent manner. Consistently, RNA sequencing database analysis revealed an association of higher KRAS MUT expression with an increase in SEMA3D and ARF6 expression in human PDAs. Moreover, multiplex immunohistochemistry analysis showed an increased number of M2-polarized macrophages proximal to nerves in human PDA tissue expressing SEMA3D. Thus, this study suggests altered expression of SEMA3D in tumor cells lead to acquisition of cancer-promoting functions and the axon guidance signaling originating from nerves is "hijacked" by tumor cells to support their growth. Other axon guidance and neuronal development molecules may play a similar dual role which is worth further investigation.

One sentence summary

Tumor- and nerve-derived SEMA3D promotes tumor progression and metastasis through macrophage reprogramming in the tumor microenvironment.

STATEMENT OF SIGNIFICANCE

This study established the dual role of axon guidance molecule, SEMA3D, in the malignant transformation of pancreatic epithelial cells and of nerve-derived SEMA3D in PDA progression and metastasis. It revealed macrophage reprogramming as the mechanism underlying bothroles. Together, this research elucidated how inflammatory responses promote invasive PDA progression and metastasis through an oncogenic process.

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.

Perineural invasion detection in pancreatic ductal adenocarcinoma using artificial intelligence

Perineural invasion (PNI) refers to the presence of cancer cells around or within nerves, raising the risk of residual tumor. Linked to worse prognosis in pancreatic ductal adenocarcinoma (PDAC), PNI is also being explored as a therapeutic target. The purpose of this work was to build a PNI detection algorithm to enhance accuracy and efficiency in identifying PNI in PDAC specimens. Training used 260 manually segmented nerve and tumor HD images from 6 scanned PDAC cases; Analytical performance analysis used 168 additional images; clinical analysis used 59 PDAC cases. The algorithm pinpointed key areas of tumor-nerve proximity for pathologist confirmation. Analytical performance reached sensitivity of 88% and 54%, and specificity of 78% and 85% for the detection of nerve and tumor, respectively. Incorporating tumor-nerve distance in clinical evaluation raised PNI detection from 52 to 81% of all cases. Interestingly, pathologist analysis required an average of only 24 s per case. This time-efficient tool accurately identifies PNI in PDAC, even with a small training cohort, by imitating pathologist thought processes.

Glutamate from nerve cells promotes perineural invasion in pancreatic cancer by regulating tumor glycolysis through HK2 mRNA-m6A modification

BACKGROUND

Perineural invasion (PNI) has a high incidence and poor prognosis in pancreatic ductal adenocarcinoma (PDAC). Our study aimed to identify the underlying molecular mechanism of PNI and propose effective intervention strategies.

METHODS

To observe PNI in vitro and in vivo, a Matrigel/ dorsal root ganglia (DRG) model and a murine sciatic nerve invasion model were respectively used. Magnetic resonance (MR) imaging and positron emission tomography/computed tomography (PET-CT) imaging were also used to evaluate tumor growth. Publicly available datasets and PDAC tissues were used to verify how the nerve cells regulate PDAC cells' PNI.

RESULTS

Our results showed that glutamate from nerve cells could cause calcium influx in PDAC cells via the N-methyl-d-aspartate receptor (NMDAR), subsequently activating the downstream Ca²⁺ dependent protein kinase CaMKII/ERK-MAPK pathway and promoting the mRNA transcription of gene METTL3. Next, METTL3 upregulates the expression of hexokinase 2 (HK2) through N6-methyladenosine (m6A) modification in mRNA, enhances the PDAC cells' glycolysis, and promotes PNI. Furthermore, the IONPs-PEG-scFvCD44v6-scAbNMDAR2B nanoparticles dual targeting CD44 variant isoform 6 (CD44v6) and t NMDAR subunit 2B (NMDAR2B) on PDAC cells were synthesized and verified showing a satisfactory blocking effect on PNI.

CONCLUSIONS

Here, we firstly provided evidence that glutamate from the nerve cells could upregulate the expression of HK2 through mRNA m6A modification via NMDAR2B and downstream Ca²⁺ dependent CaMKII/ERK-MAPK pathway, enhance the glycolysis in PDAC cells, and ultimately promote PNI. In addition, the dual targeting nanoparticles we synthesized were verified to block PNI effectively in PDAC.

Perineural Invasion in Pancreatic Ductal Adenocarcinoma: From Molecules towards Drugs of Clinical Relevance

Pancreatic ductal adenocarcinoma is one of the most threatening solid malignancies. Molecular and cellular mediators that activate paracrine signalling also regulate the dynamic interaction between pancreatic cancer cells and nerves. This reciprocal interface leads to perineural invasion (PNI), defined as the ability of cancer cells to invade nerves, similar to vascular and lymphatic metastatic cascade. Targeting PNI in pancreatic cancer might help ameliorate prognosis and pain relief. In this review, the modern knowledge of PNI in pancreatic cancer has been analysed and critically presented. We focused on molecular pathways promoting cancer progression, with particular emphasis on neuropathic pain generation, and we reviewed the current knowledge of pharmacological inhibitors of the PNI axis. PNI represents a common hallmark of PDAC and correlates with recurrence, poor prognosis and pain in pancreatic cancer patients. The interaction among pancreatic cancer cells, immune cells and nerves is biologically relevant in each stage of the disease and stimulates great interest, but the real impact of the administration of novel agents in clinical practice is limited. It is still early days for PNI-targeted treatments, and further advanced studies are needed to understand whether they could be effective tools in the clinical setting.

The Role of ECM Remodeling, EMT, and Adhesion Molecules in Cancerous Neural Invasion: Changing Perspectives

Perineural invasion (PNI) refers to the cancerous invasion of nerves. It provides an alternative route for metastatic invasion and can exist independently in the absence of lymphatic or vascular invasion. It is a prominent characteristic of specific aggressive malignancies where it correlates with poor prognosis. The clinical significance of PNI is widely recognized despite a lack of understanding of the molecular mechanisms underlying its pathogenesis. The interaction between the nerve and the cancer cells is the most pivotal PNI step which is mediated by the activation or inhibition of multiple signaling pathways that include chemokines, interleukins, nerve growth factors, and matrix metalloproteinases, to name a few. The nerve-cancer cell interaction brings about specific changes in the perineural niche, which not only affects the regular nerve functions, but also enhances the migratory, invasive, and adherent properties of the tumor cells. This review aims to elucidate the vital role of adhesion molecules, extracellular matrix, and epithelial-mesenchymal proteins that promote PNI, which may serve as therapeutic targets in the future.

microRNA-569 inhibits tumor metastasis in pancreatic cancer by directly targeting NUSAP1

MicroRNAs (miRNAs) are known to be involved in the development and progression of pancreatic cancer (PC). In this study, the prognostic significance and mechanistic role of microRNA-569 in PC were explored. Quantitative real-time PCR was used to detect the expression of microRNA-569 in PC tissues and cell lines. Scratch test and Transwell assay were conducted to detect migration and invasion ability. The xenograft nude mice model was used to determine tumor metastasis in vivo. The direct targets of microRNA-569 were determined by using bioinformatics analysis and a dual-luciferase reporter assay. The expression level of microRNA-569 was down-regulated in PC patients with a poor prognosis. In vitro and in vivo experiments indicated that over-expression of microRNA-569 inhibited the migration and invasion of PC cells. MicroRNA-569 negatively regulated NUSAP1 by directly binding its 3'-untranslated region. Further mechanism research implied that the ZEB1 pathway was involved in microRNA-569/NUSAP1 mediation of the biological behaviors in PC. These data demonstrated that microRNA-569 may exert a tumor-suppressing effect in PC and maybe a potential therapeutic target for PC patients.

Therapeutic avenues for cancer neuroscience: translational frontiers and clinical opportunities

With increasing attention on the essential roles of the tumour microenvironment in recent years, the nervous system has emerged as a novel and crucial facilitator of cancer growth. In this Review, we describe the foundational, translational, and clinical advances illustrating how nerves contribute to tumour proliferation, stress adaptation, immunomodulation, metastasis, electrical hyperactivity and seizures, and neuropathic pain. Collectively, this expanding knowledge base reveals multiple therapeutic avenues for cancer neuroscience that warrant further exploration in clinical studies. We discuss the available clinical data, including ongoing trials investigating novel agents targeting the tumour-nerve axis, and the therapeutic potential for repurposing existing neuroactive drugs as an anti-cancer approach, particularly in combination with established treatment regimens. Lastly, we discuss the clinical challenges of these treatment strategies and highlight unanswered questions and future directions in the burgeoning field of cancer neuroscience.

High‑glucose microenvironment promotes perineural invasion of pancreatic cancer via activation of hypoxia inducible factor 1α

Pancreatic cancer (PC) is one of the most lethal diseases, with a 5-year survival rate of <9%. Perineural invasion (PNI) is a common pathological hallmark of PC and is correlated with a poor prognosis in this disease. Hyperglycemia has been shown to promote the invasion and migration of PC cells; however, the effect of hyperglycemia on the PNI of PC and its underlying mechanism remains unclear. In the present study, Western blotting was utilized to detect the expression of hypoxia inducible factor 1α (HIF1α) and nerve growth factor (NGF). Transwell and wound-healing assays were performed to detect the influence of hyperglycemia on the invasion and migration ability of PC cells. An in vitro PC-dorsal root ganglion (DRG) co-culture system and an in vivo PNI sciatic nerve-infiltrating tumor model were used to evaluate the severity of PNI in hyperglycemic conditions. In the results, hyperglycemia promoted the invasion/migration ability and elevated the expression of NGF in PC by upregulating HIF1α. Moreover, in vitro short-term hyperglycemia caused little damage on the DRG axons and accelerated both the PNI of the PC and the outgrowth of the DRGs by increasing the expression of NGF via activation of HIF1α. Indeed, in vivo long-term hyperglycemia promoted the infiltration and growth of PC, and then disrupted the function of the sciatic nerve in a HIF1α-dependent manner. In conclusion, a high-glucose microenvironment promotes PNI of PC via activation of HIF1α.

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

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

Perineural Invasion and Associated Pain Transmission in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the cancers with the highest incidence of perineural invasion (PNI), which often indicates a poor prognosis. Aggressive tumor cells invade nerves, causing neurogenic inflammation; the tumor microenvironment also induces nerves to undergo a series of structural and functional reprogramming. In turn, neurons and the surrounding glial cells promote the development of pancreatic cancer through autocrine and/or paracrine signaling. In addition, hyperalgesia in PDAC patients implies alterations of pain transmission in the peripheral and central nervous systems. Currently, the studies on this topic are relatively limited. This review will elaborate on the mechanisms of tumor-neural interactions and its possible relationship with pain from several aspects that have been focused on in recent years.

Oridonin induces autophagy-mediated cell death in pancreatic cancer by activating the c-Jun N-terminal kinase pathway and inhibiting phosphoinositide 3-kinase signaling

Background

Oridonin is a diterpenoid isolated from Rabdosia rubescens that has potent anticancer activity. This study set out to investigate the antitumor effects of oridonin in pancreatic carcinoma (PC) and their underlying mechanisms.

Methods

To investigate the antitumor effects of oridonin, we developed an orthotopic C57BL/6 mouse model of PC. After successful establishment of the model, the mice were given a daily intraperitoneal injection of phosphate-buffered saline containing 0.1% dimethyl sulfoxide or oridonin for 2 weeks. In vitro experiments including MTT assay and flow cytometry were performed to examine cell viability and apoptosis. Panc-1 and Panc02 cells were transfected with a green fluorescent protein (GFP)-LC3 plasmid. After the cells had been treated with or without 20 μM oridonin and 10 μM 3-MA, the formation of GFP-LC3 puncta was detected by fluorescence microscopy. The levels of the autophagy-related proteins Beclin-1, LC3, and p62 were measured by western blotting.

Results

Oridonin inhibited the proliferation of PC cells and induced their apoptosis in vitro and in vivo. Treatment with oridonin also led to an increase in the quantity of LC3B II protein and upregulation of the p62 and Beclin-1 levels in PC cells. The effects of oridonin on PC cell proliferation, apoptosis, and autophagy were mediated via the simultaneous inhibition of the phosphoinositide 3-kinase pathway and activation of the c-Jun N-terminal kinase pathway.

Conclusions

Our study is the first to confirm the antitumor and autophagy-activating effects of oridonin on PC cells. In light of these results, oridonin may be a promising therapeutic agent for PC.

Shedding Light on the Role of Neurotransmitters in the Microenvironment of Pancreatic Cancer

Pancreatic cancer (PC) is a highly lethal malignancy with a 5-year survival rate of less than 8%. The fate of PC is determined not only by the malignant behavior of the cancer cells, but also by the surrounding tumor microenvironment (TME), consisting of various cellular (cancer cells, immune cells, stromal cells, endothelial cells, and neurons) and non-cellular (cytokines, neurotransmitters, and extracellular matrix) components. The pancreatic TME has the unique characteristic of exhibiting increased neural density and altered microenvironmental concentration of neurotransmitters. The neurotransmitters, produced by both neuron and non-neuronal cells, can directly regulate the biological behavior of PC cells via binding to their corresponding receptors on tumor cells and activating the intracellular downstream signals. On the other hand, the neurotransmitters can also communicate with other cellular components such as the immune cells in the TME to promote cancer growth. In this review, we will summarize the pleiotropic effects of neurotransmitters on the initiation and progression of PC, and particularly discuss the emerging mechanisms of how neurotransmitters influence the innate and adaptive immune responses in the TME in an autocrine or paracrine manner. A better understanding of the interplay between neurotransmitters and the immune cells in the TME might facilitate the development of new effective therapies for PC.

MicroRNAs: emerging driver of cancer perineural invasion

The perineural invasion (PNI), which refers to tumor cells encroaching on nerve, is a clinical feature frequently occurred in various malignant tumors, and responsible for postoperative recurrence, metastasis and decreased survival. The pathogenesis of PNI switches from 'low-resistance channel' hypothesis to 'mutual attraction' theory between peripheral nerves and tumor cells in perineural niche. Among various molecules in perineural niche, microRNA (miRNA) as an emerging modulator of PNI through generating RNA-induced silencing complex (RISC) to orchestrate oncogene and anti-oncogene has aroused a wide attention. This article systematically reviewed the role of microRNA in PNI, promising to identify new biomarkers and offer cancer therapeutic targets.

Unveiling the pathogenesis of perineural invasion from the perspective of neuroactive molecules

Perineural invasion (PNI) is characterized by an encounter between the cancer cells and neuronal fibers and holds an extremely poor prognosis for malignant tumors. The exact molecular mechanism behind PNI yet remains to be explored. However, it is worth-noting that an involvement of the neuroactive molecules plays a major part in this process. A complex signaling network comprising the interplay between immunological cascades and neurogenic molecules such as tumor-derived neurotrophins, neuromodulators, and growth factors constitutes an active microenvironment for PNI associated with malignancy. The present review aims at discussing the following points in relation to PNI: a) Communication between PNI and neuroplasticity mechanisms can explain the pathophysiology of poor, short and long-term outcomes in cancer patients; b) Neuroactive molecules can significantly alter the neurons and cancer cells so as to sustain PNI progression; c) Finally, careful manipulation of neurogenic pathways and/or their crosstalk with the immunological molecules implicated in PNI could provide a potential breakthrough in cancer therapeutics.

Identification of Genomic Alterations of Perineural Invasion in Patients with Stage II Colorectal Cancer

Purpose

The molecular mechanism of perineural invasion (PNI) in stage II colorectal cancer (CRC) remains not to be defined clearly. This study aims to identify the genomic aberrations related to PNI in stage II CRC.

Patients and Methods

Using array-based comparative genomic hybridization (array-CGH), primary tumor tissues and paracancerous normal tissues of stage II CRC with PNI and without PNI were analyzed. We identified genomic aberrations by using Genomic Workbench and MD-SeeGH and validated the aberrations of selected genes by real-time polymerase chain reaction (PCR). Gene ontology (GO) and pathway analysis were performed to determine the most likely biological effects of these genes.

Results

The most frequent gains in stage II CRC were at 7q11.21-q11.22, 8p11.21, 8p12-p11.23, 8q11.1-q11.22, 13q12.13-q12.2, and 20q11.21-q11.23 and the most frequent losses were at 17p13.1-p12, 8p23.2, and 118q11.2-q23. Four high-level amplifications at 8p11.23-p11.22, 18q21.1, 19q11-q12, and 20q11.21-q13.32 and homozygous deletions at 20p12.1 were discovered in Stage II CRC. Gains at 7q11.21-q22.1, 16p11.2, 17q23.3-q25.3, 19p13.3-p12, and 20p13-p11.1, and losses at 11q11-q12.1, 11p15.5-p15.1, 18p11.21, and 18q21.1-q23 were more commonly found in patients with PNI by frequency plot comparison together with detailed genomic analysis. It is also observed that gains at 8q11.1-q24.3, 9q13-q34.3, and 13q12.3-q13.1, and losses at 8p23.3-p12, 17p13.3-p11.2, and 21q22.12 occurred more frequently in patients without PNI. Further validation showed that the expression of FLT1, FBXW7, FGFR1, SLC20A2 and SERPINI1 was significantly up-regulated in the NPNI group compared to the PNI group. GO and pathway analysis revealed some genes enriched in specific pathways.

Conclusion

These involved genomic changes in the PNI of stage II CRC may be useful to reveal the mechanisms underlying PNI and provide candidate biomarkers.

MiR-10b inhibits migration and invasion of pancreatic ductal adenocarcinoma via regulating E2F7

BACKGROUND

Abnormal microRNAs (miRNAs) expression is closely related to the development and poor prognosis of pancreatic ductal adenocarcinoma (PDAC). We aimed to elucidate the invasive mechanism and clinical significance of miR-10b in PDAC.

METHODS

The RNA sequence data of pancreatic cancer were extracted from the TCGA database. R packages were performed to analyze the differential expression of RNAs. TargetScan, picTar, and miRanda were used to predict the target gene of miRNA. The expression level of the selected candidate was tested by western blot and RT-PCR in PDAC cells and tissues. Scrape and Transwell assays were determined the effect of candidate molecules on cell migration and invasion. The gain of function and loss of function was achieved by co-culture with mimics and vector. Luciferase reporters were generated based on the psiCHECK2 vector. The relative luciferase activity was measured with the Dual-Luciferase Reporter Assay System and Infinate M200 PRO microplate reader.

RESULTS

Based on the TCGA data and bioinformatics analysis, we obtained seven differentially expressed miRNAs. Both TCGA data and our center clinical date indicated that miR-10b was contributed to the poor survival of PDAC. Based on the target gene prediction database, we found that E2F7 was a target mRNA of miR-10b. In subsequent experiments in molecular biology, miR-10b expression was downregulated in PDAC cells and tissues, while E2F7 was upregulated. Scrape and Transwell assay indicated that miR-10b could inhibit the invasion and migration of PDAC. MiR-10b was confirmed to be by the E2F7 targeting site by dual-luciferase report. Moreover, rescue experiments prove that miR-10b could inhibit the invasion and migration of PDAC cells by regulating E2F7 expression.

CONCLUSION

Our results suggest that miR-10b could inhibit the progression of PDAC by regulating E2F7 expression and acts as an independent prognostic risk factor for PDAC.

Nerve input to tumours: Pathophysiological consequences of a dynamic relationship

It is well known that tumours arising in different organs are innervated and that 'perineural invasion' (cancer cells escaping from the tumour by following the nerve trunk) is a negative prognostic factor. More surprisingly, increasing evidence suggests that the nerves can provide active inputs to tumours and there is two-way communication between nerves and cancer cells within the tumour microenvironment. Cells of the immune system also interact with the nerves and cancer cells. Thus, the nerve connections can exert significant control over cancer progression and modulating these (physically or chemically) can affect significantly the cancer process. Nerve inputs to tumours are derived mainly from the sympathetic (adrenergic) and the parasympathetic (cholinergic) systems, which are interactive. An important component of the latter is the vagus nerve, the largest of the cranial nerves. Here, we present a two-part review of the nerve inputs to tumours and their effects on tumorigenesis. First, we review briefly some relevant general issues including ultrastructural aspects, stemness, interactions between neurones and primary tumours, and communication between neurones and metastasizing tumour cells. Ultrastructural characteristics include synaptic vesicles, tumour microtubes and gap junctions enabling formation of cellular networks. Second, we evaluate the pathophysiology of the nerve input to five major carcinomas: cancers of prostate, stomach, colon, lung and pancreas. For each cancer, we present (i) the nerve inputs normally present in the cancer organ and (ii) how these interact and influence the cancer process. The best clinical evidence for the role of nerves in promoting tumorigenesis comes from prostate cancer patients where metastatic progression has been shown to be suppressed significantly in cases of spinal cord injury. The balance of the sympathetic and parasympathetic contributions to early versus late tumorigenesis varies amongst the different cancers. Different branches of the vagus provide functional inputs to several of the carcinomas and, in two-way interaction with the sympathetic nervous system, affect different stages of the cancer process. Overall, the impact of the vagus nerve can be 'direct' or 'indirect'. Directly, the effect of the vagus is primarily to promote tumorigenesis and this is mediated through cholinergic receptor mechanisms. Indirectly, pro- and anti-tumour effects can occur by stimulation or inhibition of the sympathetic nervous system, respectively. Less well understood are the 'indirect' anti-tumour effect of the vagus nerve via immunomodulation/inflammation, and the role of sensory innervation. A frequent occurrence in the nerve-tumour interactions is the presence of positive feedback driven by agents like nerve growth factor. We conclude that the nerve inputs to tumours can actively and dynamically impact upon cancer progression and are open to clinical exploitation.

Linc01232 promotes the metastasis of pancreatic cancer by suppressing the ubiquitin-mediated degradation of HNRNPA2B1 and activating the A-Raf-induced MAPK/ERK signaling pathway

Pancreatic cancer (PC) is a malignant cancer with high mortality and poor prognosis. In this study, we found that Linc01232 was significantly upregulated in PC tissues and cells and higher Linc01232 expression was associated with poorer prognosis. Linc01232 overexpression promoted and Linc01232 knockdown inhibited the migration and invasion of PC cells. The results of RNA pull-down, RNA Binding Protein Immunoprecipitation (RIP) assays revealed that Linc01232 physically interacted with Heterogeneous Nuclear Ribonucleoprotein A2/B1 (HNRNPA2B1) (680-890 nt fragment with the RNA recognition motif 2 domain) to inhibit its ubiquitin-mediated degradation in PC cells. RNA sequencing was performed to obtain the transcriptional profiles regulated by Linc01232 and we further demonstrated that Linc01232 participated in the alternative splicing of A-Raf by stabilizing HNRNPA2B1 and subsequently regulated the MAPK/ERK signaling pathway. Collected, our study showed that Linc01232/HNRNPA2B1/A-Raf/MAPK axis participated in the progression of PC and provided a potential therapeutic target for PC.

Enhancing the Efficacy of CAR T Cells in the Tumor Microenvironment of Pancreatic Cancer

Pancreatic cancer has the worst prognosis and lowest survival rate among all types of cancers and thus, there exists a strong need for novel therapeutic strategies. Chimeric antigen receptor (CAR)-modified T cells present a new potential option after successful FDA-approval in hematologic malignancies, however, current CAR T cell clinical trials in pancreatic cancer failed to improve survival and were unable to demonstrate any significant response. The physical and environmental barriers created by the distinct tumor microenvironment (TME) as a result of the desmoplastic reaction in pancreatic cancer present major hurdles for CAR T cells as a viable therapeutic option in this tumor entity. Cancer cells and cancer-associated fibroblasts express extracellular matrix molecules, enzymes, and growth factors, which can attenuate CAR T cell infiltration and efficacy. Recent efforts demonstrate a niche shift where targeting the TME along CAR T cell therapy is believed or hoped to provide a substantial clinical added value to improve overall survival. This review summarizes therapeutic approaches targeting the TME and their effect on CAR T cells as well as their outcome in preclinical and clinical trials in pancreatic cancer.

Tumor-neuroglia interaction promotes pancreatic cancer metastasis

Rationale: The peripheral nervous system (PNS) plays an important role in tumor growth and progression. Schwann cells (SCs), the main glia cells of the PNS, augment cancer metastasis in contact-dependent or contact-independent manner in various malignancies. In the present study, we aimed to determine whether interplay between pancreatic cancer cells and SCs via paracrine signaling contributes to cancer progression.

Methods: Immunofluorescence analysis was performed to reveal the distribution of SCs in PDAC tissues and to determine the prognostic value and clinicopathological relevance of the level of intra‑tumoral SC markers for patients diagnosed with PDAC. Transwell assays and wound healing assays were carried out to investigate the influence of SC conditioned medium (SCM), SC co‑culture, or co-cultured CM on the migratory and invasive abilities of pancreatic cancer cells. The mechanism of SCs induced cancer cells migration and invasion was confirmed using quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assays (ELISAs), western blotting, immunofluorescence, immunohistochemistry, siRNA-mediated gene interference, and an in vivo mouse model.

Results: Immunofluorescence analysis of tissue samples revealed that there were two different types of SCs distributed in the tumor microenvironment, the presence of which correlated with several clinicopathological characteristics and overall survival for patients with PDAC. Although SCM had no impact on the motility and invasiveness of tumor cells, both co-cultivation with SCs and co‑cultured CM enhanced pancreatic cancer cell migration and invasion. Mechanistically, SC‑derived Interleukin 6 (IL6), which was induced by co-culture with pancreatic cancer cells, augmented cancer cell migration and invasion by activating STAT3 signaling in cancer cells, while IL6 neutralization or STAT3 downregulation abrogated these effects. Furthermore, Interleukin 1β (IL1β), secreted by tumor cells, activated the nuclear actor (NF)-kappa B pathway in SCs, resulting in increased cytokines production, including IL6, while inhibiting the IL1β-IL1R1 axis led to inactivation of NF-kappa B signaling and downregulated cytokines expression in SCs. Interfering with tumor-neuroglia crosstalk impeded cancer cell dissemination in vivo.

Conclusion: Schwann cells were extensively distributed in the PDAC tumor microenvironment and high level of intra-tumoral SC markers could serve as an independent prognostic factor for poor survival of patients with PDAC. The tumor-neuroglia interaction is indispensable for SCs to acquire a tumor-facilitating phenotype. Targeting the tumor-neuroglia interplay might be a promising strategy to treat PDAC.

The reciprocal regulation between host tissue and immune cells in pancreatic ductal adenocarcinoma: new insights and therapeutic implications

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-related death and is one of the most difficult-to-treat cancers. Surgical resection and adjuvant therapy have limited effects on the overall survival of PDAC patients. PDAC exhibits an immunosuppressive microenvironment, the immune response predicts survival, and activation of immune system has the potential to produce an efficacious PDAC therapy. However, chimeric antigen receptor T (CAR-T) cell immunotherapy and immune checkpoint blockade (ICB), which have produced unprecedented clinical benefits in a variety of different cancers, produce promising results in only some highly selected patients with PDAC. This lack of efficacy may be because existing immunotherapies mainly target the interactions between cancer cells and immune cells. However, PDAC is characterized by an abundant tumor stroma that includes a heterogeneous mixture of immune cells, fibroblasts, endothelial cells, neurons and some molecular events. Immune cells engage in extensive and dynamic crosstalk with stromal components in the tumor tissue in addition to tumor cells, which subsequently impacts tumor suppression or promotion to a large extent. Therefore, exploration of the interactions between the stroma and immune cells may offer new therapeutic opportunities for PDAC. In this review, we discuss how infiltrating immune cells influence PDAC development and explore the contributions of complex components to the immune landscape of tumor tissue. The roles of stromal constituents in immune modulation are emphasized. We also predict potential therapeutic strategies to target signals in the immune network in the abundant stromal microenvironment of PDAC.

Targeting cancer stem cells in drug discovery: Current state and future perspectives

In recent decades, cancer stem cells (CSCs) have been increasingly identified in many malignancies. CSC-related signaling pathways and their functions provide new strategies for treating cancer. The aberrant activation of related signaling pathways (e.g., Wnt, Notch, and Hedgehog pathways) has been linked to multiple types of malignant tumors, which makes these pathways attractive targets for cancer therapy. CSCs display many characteristic features, such as self-renewal, differentiation, high tumorigenicity, and drug resistance. Therefore, there is an urgent need to develop new therapeutic strategies to target these pathways to control stem cell replication, survival, and differentiation. Notable crosstalk occurs among different signaling pathways and potentially leads to compensatory escape. Therefore, multitarget inhibitors will be one of the main methods to overcome the drug resistance of CSCs. Many small molecule inhibitors of components of signaling pathways in CSCs have entered clinical trials, and some inhibitors, such as vismodegib, sonidegib, and glasdegib, have been approved. Tumor cells are susceptible to sonidegib and vismodegib resistance due to mutations in the Smo protein. The signal transducers and activators of transcription 3 (STAT3) inhibitor BBI608 is being evaluated in a phase III trial for a variety of cancers. Structural derivatives of BBI608 are the main focus of STAT3 inhibitor development, which is another strategy for CSC therapy. In addition to the potential pharmacological inhibitors targeting CSC-related signaling pathways, other methods of targeting CSCs are available, such as nano-drug delivery systems, mitochondrion targeting, autophagy, hyperthermia, immunotherapy, and CSC microenvironment targeting. In addition, we summarize the latest advances in the clinical development of agents targeting CSC-related signaling pathways and other methods of targeting CSCs.

Ping-Pong-Tumor and Host in Pancreatic Cancer Progression

Metastasis is the main cause of high pancreatic cancer (PaCa) mortality and trials dampening PaCa mortality rates are not satisfying. Tumor progression is driven by the crosstalk between tumor cells, predominantly cancer-initiating cells (CIC), and surrounding cells and tissues as well as distant organs, where tumor-derived extracellular vesicles (TEX) are of major importance. A strong stroma reaction, recruitment of immunosuppressive leukocytes, perineural invasion, and early spread toward the peritoneal cavity, liver, and lung are shared with several epithelial cell-derived cancer, but are most prominent in PaCa. Here, we report on the state of knowledge on the PaCIC markers Tspan8, alpha6beta4, CD44v6, CXCR4, LRP5/6, LRG5, claudin7, EpCAM, and CD133, which all, but at different steps, are engaged in the metastatic cascade, frequently via PaCIC-TEX. This includes the contribution of PaCIC markers to TEX biogenesis, targeting, and uptake. We then discuss PaCa-selective features, where feedback loops between stromal elements and tumor cells, including distorted transcription, signal transduction, and metabolic shifts, establish vicious circles. For the latter particularly pancreatic stellate cells (PSC) are responsible, furnishing PaCa to cope with poor angiogenesis-promoted hypoxia by metabolic shifts and direct nutrient transfer via vesicles. Furthermore, nerves including Schwann cells deliver a large range of tumor cell attracting factors and Schwann cells additionally support PaCa cell survival by signaling receptor binding. PSC, tumor-associated macrophages, and components of the dysplastic stroma contribute to perineural invasion with signaling pathway activation including the cholinergic system. Last, PaCa aggressiveness is strongly assisted by the immune system. Although rich in immune cells, only immunosuppressive cells and factors are recovered in proximity to tumor cells and hamper effector immune cells entering the tumor stroma. Besides a paucity of immunostimulatory factors and receptors, immunosuppressive cytokines, myeloid-derived suppressor cells, regulatory T-cells, and M2 macrophages as well as PSC actively inhibit effector cell activation. This accounts for NK cells of the non-adaptive and cytotoxic T-cells of the adaptive immune system. We anticipate further deciphering the molecular background of these recently unraveled intermingled phenomena may turn most lethal PaCa into a curatively treatable disease.