Neural invasion in pancreatic cancer: the past, present and future

Tumor-derived exosomal LINC01812 induces M2 macrophage polarization to promote perineural invasion in cholangiocarcinoma

M2 macrophages play a critical role in the tumor microenvironment of invasive solid tumors. They are closely associated with perineural invasion (PNI) and are often linked to poor prognosis. In this context, tumor-derived exosomes serve as important mediators of intercellular communication. However, the relationship between tumor cell-induced M2 macrophages and PNI in cholangiocarcinoma remains unexplored. In this study, we utilized multiplex immunofluorescence and transcriptomic sequencing to demonstrate the upregulation of LINC01812 in cholangiocarcinoma tissues and its positive correlation with M2 macrophage infiltration. Exosomal lncRNA sequencing, exosome uptake experiments, RNA pull-down assays, and mass spectrometry analysis demonstrated that macrophages can internalize exosomal LINC01812 and promote the M2 phenotype in cholangiocarcinoma cells. Additionally, Transwell and in vitro cocultures with the dorsal root ganglia confirmed that the tumor microenvironment significantly enhances the nerve infiltration of cholangiocarcinoma cells via M2 macrophages. The findings of this study indicate that exosomes containing LINC01812 derived from cholangiocarcinoma can induce M2 macrophage polarization and facilitate nerve infiltration, thereby providing new potential therapeutic targets for managing PNI in cholangiocarcinoma.

PLAU serves as a prognostic biomarker correlated with perineural invasion in HNSCC

In head and neck squamous cell carcinoma (HNSCC), perineural invasion (PNI) is a distinctive clinicopathologic feature associated with poor survival. To improve patient prognosis, our investigation delved into the underlying mechanism of PNI in HNSCC, especially laryngeal cancer and hypopharyngeal carcinoma. Based on data from the Cancer Genome Atlas (TCGA), genes were categorized into two groups based on the presence or absence of PNI. Plasminogen activator urokinase (PLAU) was screened out as the key molecular. Next, a tissue microarray comprising 68 patients with HNSCC was used to explore the association between PLAU and nerve growth factor (NGF), a positive control of PNI. Then, the co-culture model and cell damage function experiments were used to investigate the carcinogenic effect of PLAU. CCK8 and Transwell assays confirmed the role of PLAU in promoting proliferation and metastasis. The PC12 neurite growth assay and the co-culture system suggested that PLAU influences malignant behaviors by facilitating PNI. Moreover, introducing small molecule compounds to impede PLAU and NGF can effectively revert tumor progression in vivo. PLAU promotes tumor malignancy by facilitating PNI in HNSCC, offering a novel reference for clarifying the molecular mechanisms underlying PNI and identifying potential therapeutic targets for HNSCC.

Exploring the biological mechanism and clinical value of perineural invasion in pancreatic cancer

Pancreatic cancer (PC) is an extremely aggressive malignancy, with a 5-year survival rate of only 13 %. Perineural invasion (PNI) is a hallmark pathological feature of PC and is observed in almost all cases. Accordingly, PC ranks highly among solid tumors in terms of PNI incidence. The interaction between PC and the nervous system plays a pivotal role in tumor growth and metastasis. In PC, PNI is a key driver of local tumor progression, distant metastasis, and poor prognosis. Clarification of tumor-nerve crosstalk and the underlying molecular mechanisms is needed to facilitate the development of new therapeutic strategies to slow PC progression and alleviate PNI-associated symptoms. In this review, we present a comprehensive overview of the manifestations and characteristics of PNI in PC, summarize the molecular networks that regulate PNI, examine the relationship between PNI and the tumor microenvironment, and discuss the current research challenges and future directions in this critical area.

Perineural invasion in pancreatic cancer: Current biological function in R status, prognosis, and pain

Pancreatic ductal adenocarcinoma (PDAC) is predicted to become the second leading cause of death in 2030 and it is characterized by poor prognosis, recurrence and resistance to therapies. Several factors contribute to the complexity of this disease, among those the invasion of nerves by PDAC cells. This condition, defined as perineural invasion (PNI), is responsible of PDAC progression and pain generation. To date, PNI emerges as a hallmark feature of PDAC, showing the same oncological weight of lymph node metastasis in terms of prognosis. Targeting PNI could help improve prognosis and pain relief in PDAC patients. Only recently, a severity scoring system has been proposed to quantify PNI in histological samples although prospective validation and standardization are strongly advocated. More information about peripancreatic soft tissue infiltration and a "true" curative surgery could be found in understanding the molecular mechanisms of PNI. The incorporation of PNI markers for grading mesopancreas and retroperitoneal invasion is required to overcome current limitations of the histological workup. We discuss the modern understanding of PNI in PDAC, and the state of the art in clinical setting. Although there are still a lot to learn about PDAC, PNI represents one of the biological detonators and an important focus of future research.

Pancreatic cancer cells infiltrate nerves through TGFbeta1-driven perineural epithelial-to-mesenchymal-like transdifferentiation

Neural invasion is a prognostic hallmark of pancreatic ductal adenocarcinoma (PDAC), yet the underlying mechanisms behind the disruption of perineural barriers and access of cancer cells into intrapancreatic nerves remain poorly understood. This study aimed to investigate the role of epithelial-mesenchymal transformation (EMT) in perineural epithelial cells during neural invasion.Histopathological analysis of human and murine primary tumors using perineurium-specific GLUT1 antibody revealed a reduction in perineural integrity, which positively correlated with the extent of neural invasion in human PDAC cases. Human pancreatic cancer cell lines were found to secrete TGFbeta1, which induced EMT of perineural epithelial cells, characterized by the loss of epithelial markers (CK19-9) and the acquisition of mesenchymal markers (alphaSMA, N-Cadherin). Additionally, these transitioning perineural epithelial cells demonstrated increased matrix-degrading capabilities through the upregulation of matrix-metalloproteases 3 and 9 via SMAD2. In an autochthonous mouse model with elevated endogenous TGFbeta1 levels in addition to oncogenic Kras activation (Ptf1aCre/+, LSL-KrasG12D/+, LSL-R26Tgfβ/+), decreased perineural integrity could be reproduced in vivo.Collectively, these findings underscore the role played by TGFbeta1-overexpressing pancreatic cancer cells in the dismantling of perineural barriers during neural invasion.

Targeting Perineural Invasion in Pancreatic Cancer

Pancreatic cancer is an aggressive tumor with dismal prognosis. Neural invasion is one of the pathological hallmarks of pancreatic cancer. Peripheral nerves can modulate the phenotype and behavior of the malignant cells, as well as of different components of the tumor microenvironment, and thus affect tumor growth and metastasis. From a clinical point of view, neural invasion is translated into intractable pain and represents a predictor of tumor recurrence and poor prognosis. Several molecules are implicated in neural invasion and pain onset in PDAC, including neutrophins (e.g., NGF), chemokines, adhesion factors, axon-guidance molecules, different proteins, and neurotransmitters. In this review, we discuss the role of nerves within the pancreatic cancer microenvironment, highlighting how infiltrating nerve fibers promote tumor progression and metastasis, while tumor cells, in turn, drive nerve outgrowth in a reciprocal interaction that fuels tumor advancement. We outline key molecules involved in neural invasion in pancreatic cancer and, finally, explore potential therapeutic strategies to target neural invasion, aiming to both inhibit cancer progression and alleviate cancer-associated pain.

The intersection of the nervous system and breast cancer

Breast cancer (BC) represents a paradigm of heterogeneity, manifesting as a spectrum of molecular subtypes with divergent clinical trajectories. It is fundamentally characterized by the aberrant proliferation of malignant cells within breast tissue, a process modulated by a myriad of factors that govern its progression. Recent endeavors outline the interplay between BC and the nervous system, illuminate the complex symbiosis between neural structures and neoplastic cells, and elucidate nerve dependence as a cornerstone of BC progression. This includes the neural modulations on immune response, neurovascular formation, and multisystem interactions. Such insights have unveiled the critical impact of neural elements on tumor dynamics and patient prognosis. This revelation beckons a deeper exploration into the neuro-oncological interface, potentially unlocking novel therapeutic vistas. This review endeavors to delineate the intricate mechanisms between the nervous system and BC, aiming to accentuate the implications and therapeutic strategies of this intersection for tumor evolution and the formulation of innovative therapeutic approaches.

Hallmarks of perineural invasion in pancreatic ductal adenocarcinoma: new biological dimensions

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignant tumor with a high metastatic potential. Perineural invasion (PNI) occurs in the early stages of PDAC with a high incidence rate and is directly associated with a poor prognosis. It involves close interaction among PDAC cells, nerves and the tumor microenvironment. In this review, we detailed discuss PNI-related pain, six specific steps of PNI, and treatment of PDAC with PNI and emphasize the importance of novel technologies for further investigation.

Bidirectional relationship between pancreatic cancer and diabetes mellitus: a comprehensive literature review

Pancreatic cancer (PC) is a fatal malignant disease. It is well known that the relationship between PC and type 2 diabetes mellitus (T2DM) is a complicated bidirectional relationship. The most important factors causing increased risks of pancreatic cancer are hyperglycaemia, hyperinsulinemia, pancreatitis, and dyslipidemia. Genetics and the immune system also play an important role in the relationship between diabetes mellitus and pancreatic cancer. The primary contributors to this association involve insulin resistance and inflammatory processes within the tumour microenvironment. The combination of diabetes and obesity can contribute to PC by inducing hyperinsulinemia and influencing leptin and adiponectin levels. Given the heightened incidence of pancreatic cancer in diabetes patients compared to the general population, early screening for pancreatic cancer is recommended. Diabetes negatively impacts the survival of pancreatic cancer patients. Among patients receiving chemotherapy, it reduced their survival. The implementation of a healthy lifestyle, including weight management, serves as an initial preventive measure to mitigate the risk of disease development. The role of anti-diabetic drugs on survival is controversial; however, metformin may have a positive impact, especially in the early stages of cancer, while insulin therapy increases the risk of PC.

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.

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.

Noninvasive prediction of perineural invasion in intrahepatic cholangiocarcinoma by clinicoradiological features and computed tomography radiomics based on interpretable machine learning: a multicenter cohort study

BACKGROUND

Perineural invasion (PNI) of intrahepatic cholangiocarcinoma (ICC) is a strong independent risk factor for tumour recurrence and long-term patient survival. However, there is a lack of noninvasive tools for accurately predicting the PNI status. The authors develop and validate a combined model incorporating radiomics signature and clinicoradiological features based on machine learning for predicting PNI in ICC, and used the Shapley Additive explanation (SHAP) to visualize the prediction process for clinical application.

METHODS

This retrospective and prospective study included 243 patients with pathologically diagnosed ICC (training, n =136; external validation, n =81; prospective, n =26, respectively) who underwent preoperative contrast-enhanced computed tomography between January 2012 and May 2023 at three institutions (three tertiary referral centres in Guangdong Province, China). The ElasticNet was applied to select radiomics features and construct signature derived from computed tomography images, and univariate and multivariate analyses by logistic regression were used to identify the significant clinical and radiological variables with PNI. A robust combined model incorporating radiomics signature and clinicoradiological features based on machine learning was developed and the SHAP was used to visualize the prediction process. A Kaplan-Meier survival analysis was performed to compare prognostic differences between PNI-positive and PNI-negative groups and was conducted to explore the prognostic information of the combined model.

RESULTS

Among 243 patients (mean age, 61.2 years ± 11.0 (SD); 152 men and 91 women), 108 (44.4%) were diagnosed as PNI-positive. The radiomics signature was constructed by seven radiomics features, with areas under the curves of 0.792, 0.748, and 0.729 in the training, external validation, and prospective cohorts, respectively. Three significant clinicoradiological features were selected and combined with radiomics signature to construct a combined model using machine learning. The eXtreme Gradient Boosting exhibited improved accuracy and robustness (areas under the curves of 0.884, 0.831, and 0.831, respectively). Survival analysis showed the construction combined model could be used to stratify relapse-free survival (hazard ratio, 1.933; 95% CI: 1.093-3.418; P =0.021).

CONCLUSIONS

We developed and validated a robust combined model incorporating radiomics signature and clinicoradiological features based on machine learning to accurately identify the PNI statuses of ICC, and visualize the prediction process through SHAP for clinical application.

Stereotactic body radiotherapy in pancreatic adenocarcinoma

BACKGROUND

Stereotactic body radiotherapy (SBRT) in pancreatic cancer allows high delivery of radiation doses on tumors without affecting surrounding tissue. This review aimed at the SBRT application in the treatment of pancreatic cancer.

DATA SOURCES

We retrieved articles published in MEDLINE/PubMed from January 2017 to December 2022. Keywords used in the search included: "pancreatic adenocarcinoma" OR "pancreatic cancer" AND "stereotactic ablative radiotherapy (SABR)" OR "stereotactic body radiotherapy (SBRT)" OR "chemoradiotherapy (CRT)". English language articles with information on technical characteristics, doses and fractionation, indications, recurrence patterns, local control and toxicities of SBRT in pancreatic tumors were included. All articles were assessed for validity and relevant content.

RESULTS

Optimal doses and fractionation have not yet been defined. However, SBRT could be the standard treatment in patients with pancreatic adenocarcinoma in addition to CRT. Furthermore, the combination of SBRT with chemotherapy may have additive or synergic effect on pancreatic adenocarcinoma.

CONCLUSIONS

SBRT is an effective modality for patients with pancreatic cancer, supported by clinical practice guidelines as it has demonstrated good tolerance and good disease control. SBRT opens a possibility of improving outcomes for these patients, both in neoadjuvant treatment and with radical intent.

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.

Neural Invasion is an Independent Prognostic Factor in Young and Lymph Node Negative Gastric Cancer Patients Underwent Curative Gastrectomy

BACKGROUND

The prognostic significance of neural invasion (NI) in gastric cancer (GC) has not been established. This study is to investigate the characteristic and prognostic value of NI in GC.

METHODS

592 patients who had undergone gastrectomy for GC were retrospectively analyzed. NI was defined when cancer cells infiltrated into the perineurium or neural fascicles by hematoxylin and eosin staining of surgical specimens. NI and the other clinical factors were analyzed.

RESULTS

NI was detected in 270 of the 592 patients. NI was associated with tumor size, site, depth of invasion, lymph node metastasis, TNM stage, D dissection, tumor differentiation, Lauren classification, and blood vessel invasion. NI was associated with the overall survival. Multivariate analysis indicated that NI was not an independent prognostic factor for total patients, while NI independently predicted prognosis for age < 60 and lymph node metastasis negative patients by subgroup analysis. Concomitant existence of NI with tumor size ≥3cm, TNM stage III, or diffused Lauren classification independently predicted prognosis.

CONCLUSIONS

The frequency of NI is high in GC patients and increases with disease progression. NI is related to poor survival in GC patients who underwent curative gastrectomy and provides independent prognostic value for young and lymph node metastasis negative patients.

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.

Targeting the Cancer-Neuronal Crosstalk in the Pancreatic Cancer Microenvironment

Pancreatic ductal adenocarcinoma (PDAC) represents one of the most aggressive solid tumors with a dismal prognosis and an increasing incidence. At the time of diagnosis, more than 85% of patients are in an unresectable stage. For these patients, chemotherapy can prolong survival by only a few months. Unfortunately, in recent decades, no groundbreaking therapies have emerged for PDAC, thus raising the question of how to identify novel therapeutic druggable targets to improve prognosis. Recently, the tumor microenvironment and especially its neural component has gained increasing interest in the pancreatic cancer field. A histological hallmark of PDAC is perineural invasion (PNI), whereby cancer cells invade surrounding nerves, providing an alternative route for metastatic spread. The extent of PNI has been positively correlated with early tumor recurrence and reduced overall survival. Multiple studies have shown that mechanisms involved in PNI are also involved in tumor spread and pain generation. Targeting these pathways has shown promising results in alleviating pain and reducing PNI in preclinical models. In this review, we will describe the mechanisms and future treatment strategies to target this mutually trophic interaction between cancer cells to open novel avenues for the treatment of patients diagnosed with PDAC.

Arterial Resection for Pancreatic Cancer: Feasibility and Current Standing in a High-Volume Center

Background

Arterial resection (AR) during pancreatectomy for curative R0 resection of pancreatic ductal adenocarcinoma (PDAC) remains a controversial procedure with high morbidity.

Objective

To investigate the feasibility and oncological outcomes of pancreatectomy combined with AR at a high-volume center for pancreatic surgery.

Methods

We retrospectively analyzed our experience in PDAC patients, who underwent pancreatic resection with AR and/or venous resection (VR) between 2007 and 2021.

Results

In total 259 PDAC patients with borderline resectable (n = 138) or locally advanced (n = 121) PDAC underwent vascular resection during tumor resection. From these, 23 patients had AR (n = 4 due to intraoperative injury, n = 19 due to suspected arterial infiltration). However, 12 out of 23 patients (52.2%) underwent simultaneous VR including 1 case with intraoperative arterial injury. In comparison, 11 patients (47.8%) underwent AR only including 3 intraoperative arterial injury patients. Although the operation time and bleeding rate of patients with AR were respectively longer and higher than in VR, no significant difference was detected in postoperative complications between VR and AR (P = 0.11). The final histopathological findings of PDAC patients were similar, including M stage, regional lymph node metastases, and R0 margin resection. The mortality of the entire cohort was 6.2% (16/259), with a tendency to increase mortality in the AR cohort, yet without statistical significance (VR: 5% vs AR: 21.1%; P = 0.05). Although 19 (82.6%) patients had PDAC in the final histopathology, only 6 were confirmed to have infiltrated arteria. The microscopic distribution of PDAC in these infiltrated arterial walls on hematoxylin-eosin staining was classified into 3 patterns. Strikingly, the perivascular nerves frequently exhibited perineural invasion.

Conclusions

AR can be performed in high-volume centers for pancreatic surgery with an acceptable morbidity, which is comparable to that of VR. However, the likelihood of arterial infiltration seems to be rather overestimated, and as such, AR might be avoidable or replaced by less invasive techniques such as divestment during PDAC surgery.

The clinical implications and molecular features of intrahepatic cholangiocarcinoma with perineural invasion

BACKGROUND

Perineural invasion (PNI) is associated with metastasis in malignancies, including intrahepatic cholangiocarcinoma (ICC), and is correlated with poor prognosis.

METHODS

The study included three large cohorts: ZS-ICC and TMA cohorts from our team, MSK cohort from a public database, and a small cohort named cohort 4. Prognostic implications of PNI were investigated in MSK cohort and TMA cohort. PNI-related genomic and transcriptomic profiles were analyzed in MSK and ZS-ICC cohorts. GO, KEGG, and ssGSEA analyses were performed. Immunohistochemistry was used to investigate the relationship between PNI and markers of neurons, hydrolases, and immune cells. The efficacy of adjuvant therapy in ICC patients with PNI was also assessed.

RESULTS

A total of 30.6% and 20.7% ICC patients had PNI in MSK and TMA cohorts respectively. Patients with PNI presented with malignant phenotypes such as high CA19-9, the large bile duct type, lymph node invasion, and shortened overall survival (OS) and relapse-free survival (RFS). Nerves involved in PNI positively express tyrosine hydroxylase (TH), a marker of sympathetic nerves. Patients with PNI showed high mutation frequency of KRAS and an immune suppressive metastasis prone niche of decreased NK cell, increased neutrophil, and elevated PD-L1, CD80, and CD86 expression. Patients with PNI had an extended OS after adjuvant therapy with TEGIO, GEMOX, or capecitabine.

CONCLUSION

Our study deciphered the genomic features and the immune suppressive metastasis-prone niche in ICC with PNI. Patients with PNI showed a poor prognosis after surgery but a good response to adjuvant chemotherapy.

Construction of a pancreatic cancer nerve invasion system using brain and pancreatic cancer organoids

Pancreatic cancer (PC) is a fatal malignancy in the human abdominal cavity that prefers to invade the surrounding nerve/nerve plexus and even the spine, causing devastating and unbearable pain. The limitation of available in vitro models restricts revealing the molecular mechanism of pain and screening pain-relieving strategies to improve the quality of life of end-stage PC patients. Here, we report a PC nerve invasion model that merged human brain organoids (hBrO) with mouse PC organoids (mPCO). After merging hBrOs with mPCOs, we monitored the structural crosstalk, growth patterns, and mutual interaction dynamics of hBrO with mPCOs for 7 days. After 7 days, we also analyzed the pathophysiological statuses, including proliferation, apoptosis and inflammation. The results showed that mPCOs tend to approximate and intrude into the hBrOs, merge entirely into the hBrOs, and induce the retraction/shrinking of neuronal projections that protrude from the margin of the hBrOs. The approximating of mPCOs to hBrOs accelerated the proliferation of neuronal progenitor cells, intensified the apoptosis of neurons in the hBrOs, and increased the expression of inflammatory molecules in hBrOs, including NLRP3, IL-8, and IL-1β. Our system pathophysiologically replicated the nerve invasions in mouse GEMM (genetically engineered mouse model) primary and human PCs and might have the potential to be applied to reveal the molecular mechanism of nerve invasion and screen therapeutic strategies in PCs.

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.

Pancreatic intra-arterial infusion chemotherapy for the treatment of patients with advanced pancreatic carcinoma: A pilot study

OBJECTIVE

To preliminarily evaluate the efficacy and safety of pancreatic intra-arterial infusion chemotherapy (PAIC) with nab-paclitaxel in patients with advanced pancreatic carcinoma.

METHODS

Fifteen patients with advanced pancreatic carcinoma received monthly, inpatient, 3-h, continuous PAIC of nab-paclitaxel at 180 mg/m2, combined with 60 mg oral tegafur gimeracil oteracil potassium capsule for 2 weeks. The therapeutic courses were repeated every 4 weeks. All patients had a preliminary diagnosis based on clinical symptoms, imaging data (computed tomography or magnetic resonance imaging or positron emission tomography/computed tomography), and tumor markers. The adverse effects, clinical benefit response (CBR), objective response rate (ORR), median progression free survival (mPFS), and median overall survival (mOS) were monitored.

RESULTS

Fifteen patients with advanced pancreatic carcinoma were enrolled in this study, including 10 male and 5 female patients. The mean age at the time of treatment was 66.3 years (53-84 years). A total of 49 cycles of PAIC (mean = 3.27 cycles/patient) were performed. The most common treatment-related toxicities were alopecia, diarrhea, and nausea/vomiting. No procedure-related complications were observed. The longest overall survival observed was 22 months and the maximum number of treatments for the same patient was six cycles. PAIC contributed a high rate (13/15 [86.67%]) and fast (10/15 [66.67%]) easement of pain, with apparent symptom relief within 24 h, especially local pain symptom. The pain anesis rate was 13 (86.67%). CBR was achieved in 13 (86.67%) patients (95%CI [59.54,98.34]). ORR was achieved in four (26.67%) patients (95%CI [7.79,55.10]). Disease Control Rate was achieved in 14 (93.33%) patients. The mPFS was 5.22 months (interquartile range [IQR], 4.27-7.85 months). The mOS was 8.97 months (IQR, 5.65-13.70 months).

CONCLUSIONS

In this study, the dose of the chemotherapeutics and the schedule of the transcatheter pancreatic arterial chemotherapy perfusion were shown to be safe, well-tolerated, and effective for the relief of clinical symptoms and CBR. These advantages can quickly establish the treatment belief and improve patient quality of life. This regimen requires further investigation in patients with advanced pancreatic carcinoma.

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.

Neural Component of the Tumor Microenvironment in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive primary malignancy of the pancreas, with a dismal prognosis and limited treatment options. It possesses a unique tumor microenvironment (TME), generating dense stroma with complex elements cross-talking with each other to promote tumor growth and progression. Diversified neural components makes for not having a full understanding of their influence on its aggressive behavior. The aim of the study was to summarize and integrate the role of nerves in the pancreatic tumor microenvironment. The role of autonomic nerve fibers on PDAC development has been recently studied, which resulted in considering the targeting of sympathetic and parasympathetic pathways as a novel treatment opportunity. Perineural invasion (PNI) is commonly found in PDAC. As the severity of the PNI correlates with a poorer prognosis, new quantification of this phenomenon, distinguishing between perineural and endoneural invasion, could feature in routine pathological examination. The concepts of cancer-related neurogenesis and axonogenesis in PDAC are understudied; so, further research in this field may be warranted. A better understanding of the interdependence between the neural component and cancer cells in the PDAC microenvironment could bring new nerve-oriented treatment options into clinical practice and improve outcomes in patients with pancreatic cancer. In this review, we aim to summarize and integrate the current state of knowledge and future challenges concerning nerve-cancer interactions in PDAC.

TIMP1 derived from pancreatic cancer cells stimulates Schwann cells and promotes the occurrence of perineural invasion

Perineural invasion (PNI) occurs in most pancreatic ductal adenocarcinomas (PDACs). The relationship between cancer cells and peripheral nerves, however, is unknown. Therefore, we focused on the cooperation of PDAC cells and peripheral nerve astrocytes, Schwann cells (SCs), in PNI. The mutual tumor-supportive secretory cytokines between SCs (sNF96.2) and PDAC cells (PANC-1, BxPC-3) were screened by human cytokine arrays and verified. The prognostic value of selected cytokines and SC-associated markers was confirmed in PDAC patients. TIMP1 and CCL7 were found to form a paracrine feedback loop between PDAC cells and SCs. PDAC cell-derived TIMP1 promotes SCs proliferation and migration via CD63/PI3K/AKT signaling. CCL7 secreted from SCs enhances PDAC cell migration, invasion and expression of TIMP1 via CCR2/STAT3. PDAC cell-SC cooperation in PNI was blocked when TIMP1 knockdown in vitro and in vivo. Finally, TIMP1, CCL7 and SC-associated markers were correlated with PNI and prognosis in PDAC patients. In conclusion, SCs collaborate with PDAC cells through the TIMP1-CCL7 paracrine feedback loop to promote PNI. TIMP1 knockdown in PDAC cells suppresses PNI. Strategies to disrupt the TIMP1-CCL7 feedback loop might be developed to inhibit PNI in PDAC.

The Role of Neural Signaling in the Pancreatic Cancer Microenvironment

Simple Summary

Pancreatic cancer is a highly lethal malignant disease with a dense stroma, called the tumor microenvironment. Accumulating evidence indicates the important role of sympathetic, parasympathetic, and sensory nerves in the tumor microenvironment of various cancers, including pancreatic cancer. Cancer cells and neural cells interact with each other to form a complex network and cooperatively promote cancer growth and invasion. In this review article, we describe the current understanding of the role of nerves in the tumor microenvironment.

Abstract

Pancreatic cancer is one of the most lethal malignant diseases. Various cells in the tumor microenvironment interact with tumor cells and orchestrate to support tumor progression. Several kinds of nerves are found in the tumor microenvironment, and each plays an essential role in tumor biology. Recent studies have shown that sympathetic, parasympathetic, and sensory neurons are found in the pancreatic cancer microenvironment. Neural signaling not only targets neural cells, but tumor cells and immune cells via neural receptors expressed on these cells, through which tumor growth, inflammation, and anti-tumor immunity are affected. Thus, these broad-range effects of neural signaling in the pancreatic cancer microenvironment may represent novel therapeutic targets. The modulation of neural signaling may be a therapeutic strategy targeting the whole tumor microenvironment. In this review, we describe the current understanding of the role of nerves in the tumor microenvironment of various cancers, with an emphasis on pancreatic cancer. We also discuss the underlying mechanisms and the possibility of therapeutic applications.

Genetic Mouse Models to Study Pancreatic Cancer-Induced Pain and Reduction in Well-Being

In addition to the poor prognosis, excruciating abdominal pain is a major challenge in pancreatic cancer. Neurotropism appears to be the underlying mechanism leading to neuronal invasion. However, there is a lack of animal models suitable for translationally bridging in vitro findings with clinical trials. We characterized KPC (KrasG12D/+; Trp53R172H/+; P48-Cre) and KPPC (KrasG12D/+; Trp53R172H/R172H; P48-Cre) mice with genetically determined pancreatic ductal adenocarcinoma (PDAC) and compared them with an orthotopic pancreatic cancer mouse model, healthy littermates and human tissue. We analyzed behavioral correlates of cancer-associated pain and well-being, and studied neuronal remodeling and cytokine expression. Histologically, we found similarities between KPC and KPPC tissue with human samples. Compared to healthy littermates, we detect nerve fiber hypertrophy, which was not restricted to a certain fiber type. Interestingly, while KPPC mice showed significantly reduced well-being, KPC mice emerged to be better suited for studying long-lasting cancer pain that emerges over a slow course of tumor progression. To address the neuroinflammatory correlate of loss of well-being, we studied cytokine levels in KPPC mice and observed a significant upregulation of CXCL16, TNFRSF5, CCL24, CXCL1, CCL22, CLL20 and CX2CL1. In summary, we demonstrate that the KPC mouse model is best suited to studying cancer pain, whereas the KPPC model can be employed to study cancer-associated reduction in well-being.

Computed Tomography-Guided Coeliac Plexus Neurolysis in Palliative in-Patients with Intra-Abdominal Malignancy: Retrospective Evaluation of Neurolytic Solution Spread as a Predictive Factor

INTRODUCTION

Computed tomography (CT)-guided coeliac plexus neurolysis (CPN) is considered effective at controlling pain in patients with intra-abdominal malignancies. The primary objective was to correlate pain outcomes with the spread of neurolytic solution in the coeliac area and to evaluate the predictive value for the spread of injectate for pain outcomes and side effects.

METHODS

Blinded CT scans were reviewed. The coeliac area was divided into nine quadrants. Assessors evaluated quadrants according to contrast spread, needle tip position, and the contact between the injectate and other organs and plexuses. Efficacy of CPN and complications were estimated.

RESULTS

In 54.9% there was complete spread of the neurolytic in the coeliac area with no correlation between pain relief and spread of injectate. In 85% the neurolytic had contact with viscera with no correlation with pain relief or complications. There was no correlation between needle tip position and spread of the neurolytic and contact of the neurolytic with viscera. In 71.6% the injectate was found to have spread into "other" plexuses. In 13.3% hampered spread of the injectate was observed. There was no correlation between patterns of injectate spread and pain relief, pain relief and spread of injectate in any particular quadrants, and expected and documented post-procedural pain scores.

CONCLUSIONS

Based on the spread of contrast medium clinicians can neither correctly anticipate the pain relief or post-procedural NRS, nor the duration of pain relief and complications. It is not essential to have the perfect sickle-shaped spread of the injectate for adequate pain control.

Emerging Roles of the Nervous System in Gastrointestinal Cancer Development

Simple Summary

Nerve–cancer cross-talk has increasingly become a focus of the oncology field, particularly in gastrointestinal (GI) cancers. The indispensable roles of the nervous system in GI tumorigenesis and malignancy have been dissected by epidemiological, experimental animal and mechanistic data. Herein, we review and integrate recent discoveries linking the nervous system to GI cancer initiation and progression, and focus on the molecular mechanisms by which nerves and neural receptor pathways drive GI malignancy.

Abstract

Our understanding of the fascinating connection between nervous system and gastrointestinal (GI) tumorigenesis has expanded greatly in recent years. Recent studies revealed that neurogenesis plays an active part in GI tumor initiation and progression. Tumor-driven neurogenesis, as well as neurite outgrowth of the pre-existing peripheral nervous system (PNS), may fuel GI tumor progression via facilitating cancer cell proliferation, chemoresistance, invasion and immune escape. Neurotransmitters and neuropeptides drive the activation of various oncogenic pathways downstream of neural receptors within cancer cells, underscoring the importance of neural signaling pathways in GI tumor malignancy. In addition, neural infiltration also plays an integral role in tumor microenvironments, and contributes to an environment in favor of tumor angiogenesis, immune evasion and invasion. Blockade of tumor innervation via denervation or pharmacological agents may serve as a promising therapeutic strategy against GI tumors. In this review, we summarize recent findings linking the nervous system to GI tumor progression, set the spotlight on the molecular mechanisms by which neural signaling fuels cancer aggressiveness, and highlight the importance of targeting neural mechanisms in GI tumor therapy.

Single-Fraction Celiac Plexus Radiosurgery: A Preliminary Proof-of-Concept Phase 2 Clinical Trial

BACKGROUND

Refractory epigastric/midback pain is associated with locally advanced abdominal malignancies, especially pancreatic cancer. The pain is caused by tumor infiltration of the celiac plexus, a nerve network attached to the abdominal aorta. Contemporary palliative approaches are often inadequate. We hypothesized that ablative radiation targeted to the celiac plexus would alleviate this pain.

METHODS AND MATERIALS

We performed a single-arm prospective clinical trial (ClinicalTrials.gov identifier: NCT02356406). Eligible and evaluable patients had celiac pain of at least 5 out of 10 on the Numerical Rating Scale, completed treatment per protocol, and had at least 1 posttreatment visit. The entire retroperitoneal celiac plexus was irradiated with a single 25-Gy fraction. The primary endpoint was change in the Numerical Rating Scale 3 weeks posttreatment. Toxic effects and pain interference (as measured with the Brief Pain Inventory) were secondary endpoints.

RESULTS

For our study, 31 patients signed consent, and, of these, 18 patients were treated and evaluable. Median age was 68 years (range, 51-79); 89% of the patients had pancreatic cancer; the median Eastern Cooperative Oncology Group performance status was 1; and the median interval from initial diagnosis to treatment was 9 months (range, 1-36), and, in this interval, patients received a median of 1 systemic treatment line (range, 0-3). Acute toxicity was limited to grade 1 to 2. Three weeks after treatment, 16 patients (84%) reported decreased celiac pain, with median pain level falling from 6 out of 10 (interquartile range [IQR], 5.0-7.5) at baseline to 3 out of 10 (IQR, 1.0-4.3); six weeks after treatment, the Numerical Rating Scale number fell further to 2.8 out of 10 (IQR, 0-3.3; both P < .005 vs baseline), including 4 patients who reported complete eradication of their celiac pain. Total daily morphine milligram equivalents decreased from 59 pretreatment to 50 at 3 weeks, and from 50 to 45 at 6 weeks. Significant improvement was seen in pain-interference scores.

CONCLUSIONS

Celiac plexus radiosurgery appears to alleviate cancer-related pain. An international multicenter phase 2 trial is currently accruing.

Regulation of Carcinogenesis by Sensory Neurons and Neuromediators

Interactions between the immune system and the nervous system are crucial in maintaining homeostasis, and disturbances of these neuro-immune interactions may participate in carcinogenesis and metastasis. Nerve endings have been identified within solid tumors in humans and experimental animals. Although the involvement of the efferent sympathetic and parasympathetic innervation in carcinogenesis has been extensively investigated, the role of the afferent sensory neurons and the neuropeptides in tumor development, growth, and progression is recently appreciated. Similarly, current findings point to the significant role of Schwann cells as part of neuro-immune interactions. Hence, in this review, we mainly focus on local and systemic effects of sensory nerve activity as well as Schwann cells in carcinogenesis and metastasis. Specific denervation of vagal sensory nerve fibers, or vagotomy, in animal models, has been reported to markedly increase lung metastases of breast carcinoma as well as pancreatic and gastric tumor growth, with the formation of liver metastases demonstrating the protective role of vagal sensory fibers against cancer. Clinical studies have revealed that patients with gastric ulcers who have undergone a vagotomy have a greater risk of stomach, colorectal, biliary tract, and lung cancers. Protective effects of vagal activity have also been documented by epidemiological studies demonstrating that high vagal activity predicts longer survival rates in patients with colon, non-small cell lung, prostate, and breast cancers. However, several studies have reported that inhibition of sensory neuronal activity reduces the development of solid tumors, including prostate, gastric, pancreatic, head and neck, cervical, ovarian, and skin cancers. These contradictory findings are likely to be due to the post-nerve injury-induced activation of systemic sensory fibers, the level of aggressiveness of the tumor model used, and the local heterogeneity of sensory fibers. As the aggressiveness of the tumor model and the level of the inflammatory response increase, the protective role of sensory nerve fibers is apparent and might be mostly due to systemic alterations in the neuro-immune response. Hence, more insights into inductive and permissive mechanisms, such as systemic, cellular neuro-immunological mechanisms of carcinogenesis and metastasis formation, are needed to understand the role of sensory neurons in tumor growth and spread.

Exploring the Role of Metabolites in Cancer and the Associated Nerve Crosstalk

Since Otto Warburg's first report on the increased uptake of glucose and lactate release by cancer cells, dysregulated metabolism has been acknowledged as a hallmark of cancer that promotes proliferation and metastasis. Over the last century, studies have shown that cancer metabolism is complex, and by-products of glucose and glutamine catabolism induce a cascade of both pro- and antitumorigenic processes. Some vitamins, which have traditionally been praised for preventing and inhibiting the proliferation of cancer cells, have also been proven to cause cancer progression in a dose-dependent manner. Importantly, recent findings have shown that the nervous system is a key player in tumor growth and metastasis via perineural invasion and tumor innervation. However, the link between cancer-nerve crosstalk and tumor metabolism remains unclear. Here, we discuss the roles of relatively underappreciated metabolites in cancer-nerve crosstalk, including lactate, vitamins, and amino acids, and propose the investigation of nutrients in cancer-nerve crosstalk based on their tumorigenicity and neuroregulatory capabilities. Continued research into the metabolic regulation of cancer-nerve crosstalk will provide a more comprehensive understanding of tumor mechanisms and may lead to the identification of potential targets for future cancer therapies.

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.

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.

Eukaryotic initiation factor 2 signaling behind neural invasion linked with lymphatic and vascular invasion in pancreatic cancer

Perineural invasion (PNI) is a typical poor prognostic factor in pancreatic ductal adenocarcinoma (PDAC). The mechanisms linking PNI to poor prognosis remain unclear. This study aimed to clarify what changes occurred alongside PNI in PDAC. A 128-patient cohort undergoing surgery for early-stage PDAC was evaluated. Subdivided into two groups, according to pathological state, a pancreatic nerve invasion (ne) score of less than three (from none to moderate invasion) was designated as the low-grade ne group. The high-grade (marked invasion) ne group (74 cases, 57.8%) showed a higher incidence of lymphatic metastasis (P = 0.002), a higher incidence of early recurrence (P = 0.004), decreased RFS (P < 0.001), and decreased DSS (P < 0.001). The severity of lymphatic (r = 0.440, P = 0.042) and venous (r = 0.610, P = 0.002) invasions was positively correlated with the ne score. Tumors having abundant stroma often displayed severe ne. Proteomics identified eukaryotic initiation factor 2 (EIF2) signaling as the most significantly enriched pathway in high-grade ne PDAC. Additionally, EIF2 signaling-related ribosome proteins decreased according to severity. Results showed that PNI is linked with lymphatic and vascular invasion in early-stage PDAC. Furthermore, the dysregulation of proteostasis and ribosome biogenesis can yield a difference in PNI severity.

Roles of the nervous system in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC), with its extremely poor prognosis, presents a substantial health problem worldwide. Outcomes have improved thanks to progress in surgical technique, chemotherapy, pre-/postoperative management, and centralization of patient care to high-volume centers. However, our goals are yet to be met. Recently, exome sequencing using PDAC surgical specimens has demonstrated that the most frequently altered genes were the axon guidance genes, indicating involvement of the nervous system in PDAC carcinogenesis. Moreover, perineural invasion has been widely identified as one poor prognostic factor. The combination of innovative technologies and extensive clinician experience with the nervous system come together here to create a new treatment option. However, evidence has emerged that suggests that the relationship between cancer and nerves in PDAC, the underlying mechanism, is not fully understood. In an attempt to tackle this lethal cancer, this review summarizes the anatomy and physiology of the pancreas and discusses the role of the nervous system in the pathophysiology of PDAC.

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.

Association of Mu-Opioid Receptor(MOR) Expression and Opioids Requirement With Survival in Patients With Stage I-III Pancreatic Ductal Adenocarcinoma

Background

The use of opioids in patients with metastatic pancreatic ductal adenocarcinoma (PDAC) is associated with shorter survival and not dependent on the expression of the mu-opioid receptor (MOR). The role of opioid use and MOR expression in stage I-III PDAC has not been investigated.

Methods

We conducted retrospective study in patients with stage I-III PDAC. MOR expression and OPRM1 gene expression in tumour tissue and non-tumour tissue was measured. Primary endpoints were overall survival (OS) and disease-free survival (DFS). Secondary endpoints included perineural invasion, intraoperative sufentanil consumption, and length of stay. We performed a subgroup group analysis to evaluate the interaction between levels of MOR expression, amount of opioids use (high versus low) and its association with survival.

Results

A total of 236 patients were enrolled in this study.There were no significantly difference in OS rates in patients with high versus low levels of MOR (1-year OS: 65.2% versus 70.6%, P=0.064; 3-year: 31.4% versus 35.8%, P=0.071; 5-year: 19.4% versus. 16.2%, P=0.153, respectively) in the tumours. The DFS rates between the groups were no significantly difference. Of note, a high expression of MOR combined with high opioid consumption was associated with poor prognosis in stage I-III PDAC patients. Tumor expressing high levels of MOR show higher rates of perineural invasion.

Conclusion

MOR is not an independent predictor of poor survival in stage I-III PDAC but associated with perineural invasion. Patients requiring high amounts of opioids intraoperatively show worse outcome if they are expressing high levels of MOR.

Role of the nervous system in cancers: a review

Nerves are important pathological elements of the microenvironment of tumors, including those in pancreatic, colon and rectal, prostate, head and neck, and breast cancers. Recent studies have associated perineural invasion with tumor progression and poor outcomes. In turn, tumors drive the reprogramming of neurons to recruit new nerve fibers. Therefore, the crosstalk between nerves and tumors is the hot topic and trend in current cancer investigations. Herein, we reviewed recent studies presenting direct supporting evidences for a better understanding of nerve-tumor interactions.

Nerve fibers in the tumor microenvironment in neurotropic cancer-pancreatic cancer and cholangiocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) and cholangiocarcinoma (CCA) are both deadly cancers and they share many biological features besides their close anatomical location. One of the main histological features is neurotropism, which results in frequent perineural invasion. The underlying mechanism of cancer cells favoring growth by and through the nerve fibers is not fully understood. In this review, we provide knowledge of these cancers with frequent perineural invasion. We discuss nerve fiber crosstalk with the main different components of the tumor microenvironment (TME), the immune cells, and the fibroblasts. Also, we discuss the crosstalk between the nerve fibers and the cancer. We highlight the shared signaling pathways of the mechanisms behind perineural invasion in PDAC and CCA. Hereby we have focussed on signaling neurotransmitters and neuropeptides which may be a target for future therapies. Furthermore, we have summarized retrospective results of the previous literature about nerve fibers in PDAC and CCA patients. We provide our point of view in the potential for nerve fibers to be used as powerful biomarker for prognosis, as a tool to stratify patients for therapy or as a target in a (combination) therapy. Taking the presence of nerves into account can potentially change the field of personalized care in these neurotropic cancers.

The Key Genes for Perineural Invasion in Pancreatic Ductal Adenocarcinoma Identified With Monte-Carlo Feature Selection Method

Background

Pancreatic ductal adenocarcinoma (PDAC) is the most aggressive form of pancreatic cancer. Its 5-year survival rate is only 3–5%. Perineural invasion (PNI) is a process of cancer cells invading the surrounding nerves and perineural spaces. It is considered to be associated with the poor prognosis of PDAC. About 90% of pancreatic cancer patients have PNI. The high incidence of PNI in pancreatic cancer limits radical resection and promotes local recurrence, which negatively affects life quality and survival time of the patients with pancreatic cancer.

Objectives

To investigate the mechanism of PNI in pancreatic cancer, we analyzed the gene expression profiles of tumors and adjacent tissues from 50 PDAC patients which included 28 patients with perineural invasion and 22 patients without perineural invasion.

Method

Using Monte-Carlo feature selection and Incremental Feature Selection (IFS) method, we identified 26 key features within which 15 features were from tumor tissues and 11 features were from adjacent tissues.

Results

Our results suggested that not only the tumor tissue, but also the adjacent tissue, was informative for perineural invasion prediction. The SVM classifier based on these 26 key features can predict perineural invasion accurately, with a high accuracy of 0.94 evaluated with leave-one-out cross validation (LOOCV).

Conclusion

The in-depth biological analysis of key feature genes, such as TNFRSF14, XPO1, and ATF3, shed light on the understanding of perineural invasion in pancreatic ductal adenocarcinoma.

Comparison of Radiation Treatment Volumes for Borderline Resectable Pancreatic Cancer in Contemporary Clinical Trials

OBJECTIVES

Optimal radiation target volumes for neoadjuvant therapy in patients with borderline resectable pancreatic cancer (BRPCa) are undefined. Most local recurrences are near the celiac axis and superior mesenteric artery. Methods for generating radiation target volumes include symmetric expansion around the tumor or a customized vascular based approach. We investigated 3 current prospective trials' coverage of vascular regions at increased risk of recurrence by comparing them to 2 reference standards.

MATERIALS AND METHODS

Fourteen computed tomography simulation scans from an institutional prospective trial on BRPCa were used to replicate distinct volumes corresponding to each of 3 contemporary BRPCa trials. Trial volumes were compared with 2 reference volumes (vascular planning target volume and Hopkins planning target volume), which were both based on vascular regions at increased risk of recurrence. Boolean operators and DICE analyses were performed to evaluate trial volume coverage of reference standards.

RESULTS

A total of 42 target volumes and 28 reference volumes were created using the 14-patient data set. DICE coefficients were highly variable ranging from 0.11 to 0.99. Mean % coverage of reference volumes ranged from 5.8% to 98.6%.

CONCLUSIONS

The wide range of DICE coefficients and coverage indicate heterogeneity in high risk vascular target coverage using symmetric Boolean expansions from the primary tumor. This approach may inadequately cover regions at high risk of local recurrence in BRPCa. A customized clinical target volume that specifically includes the superior mesenteric artery and celiac axis will improve coverage to this region and will account for individual and tumor variability.

Patterns of Failure After Neoadjuvant Stereotactic Body Radiation Therapy or Fractionated Chemoradiation in Resectable and Borderline Resectable Pancreatic Cancer

OBJECTIVES

The goal of this study was to compare outcomes of patients with borderline and resectable pancreatic cancer treated with neoadjuvant stereotactic body radiation therapy (SBRT) versus fractionated chemoradiation.

METHODS

Patients with borderline or resectable pancreatic cancer treated with neoadjuvant intent between November 2011 and December 2017 were reviewed. The SBRT volume/dose was 33 Gy in 5 fractions to gross tumor plus abutting vessel with or without 25 Gy in 5 fractions to pancreatic head/body and celiac/superior mesenteric artery. Fractionated chemoradiation volume/dose was 50.4 Gy in 28 fractions to gross tumor, superior mesenteric/celiac arteries, and enlarged lymph nodes with concurrent bolus 5-FU, leucovorin, oxaliplatin, irinotecan or gemcitabine/nab-paclitaxel. Failure patterns, local recurrence-free survival (LRFS), progression-free survival (PFS), and overall survival were assessed.

RESULTS

Forty-three patients were reviewed (18 SBRTs and 25 fractionated). Among patients who underwent resection, patients treated with fractionated chemoradiation had improved LRFS (12-month LRFS, 86% vs 62%, P = 0.003) and PFS (median PFS, 23 months vs 11 months, P = 0.006) compared with SBRT. There was no difference in overall survival.

CONCLUSIONS

Stereotactic body radiation therapy may result in inferior LRFS and PFS compared with fractionated chemoradiation, likely because of under coverage of high-risk vascular targets.

Extrapancreatic Nerve Plexus Invasion on Imaging Predicts Poor Survival After Upfront Surgery for Anatomically Resectable Pancreatic Cancer

OBJECTIVES

This study aimed to analyze the risk factors for poor survival of the patients with anatomically resectable pancreatic ductal adenocarcinoma (PDAC), focusing on detailed computed tomography (CT) findings of tumor extent to the peripancreatic tissue.

METHODS

The study included 192 patients who underwent upfront pancreaticoduodenectomy for anatomically resectable PDAC. Preoperative CT images were rereviewed by an experienced radiologist for the pattern of tumor extension to the surrounding tissue: biliary, duodenal, serosal, retroperitoneal, portal venous, arterial, extrapancreatic nerve plexus, and other-organ invasion. Imaging findings and other clinical data that could be obtained before surgery were evaluated for their association with a shorter disease-specific survival (DSS) and recurrence-free survival (RFS).

RESULTS

Of the 192 anatomically resectable PDAC patients, extrapancreatic nerve plexus invasion was observed on CT in 38 patients (20%), and this finding was independently associated with a shorter DSS (hazard ratio, 2.258; P < 0.001) and RFS (hazard ratio, 2.665; P < 0.001). The median survival of patients with and without extrapancreatic nerve plexus invasion on CT was 19.7 versus 38.5 months (P < 0.001).

CONCLUSIONS

Extrapancreatic nerve plexus invasion was shown as an only CT finding associated with a shorter DSS and RFS after upfront surgery for the patients with anatomically resectable PDAC.

Oncolytic Virus-Mediated Targeting of the ERK Signaling Pathway Inhibits Invasive Propensity in Human Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) cells have an exceptional ability to invade nerves through pronounced crosstalk between nerves and cancer cells; however, the mechanism of PDAC cell invasion remains to be elucidated. Here, we demonstrate the therapeutic potential of telomerase-specific oncolytic adenoviruses, OBP-301 and tumor suppressor p53-armed OBP-702, against human PDAC cells. Highly invasive PDAC cells exhibited higher levels of phosphorylated extracellular signal-regulated kinases 1 and 2 (ERK1/2) expression independent of KRAS expression; ERK1/2 inhibitor or small interfering RNA (siRNA) treatment significantly reduced the migration and invasion of PDAC cells, suggesting that the ERK signaling pathway is associated with the invasiveness of PDAC cells. OBP-702 infection suppressed ERK signaling and inhibited PDAC cell migration and invasion more efficiently than OBP-301. OBP-702 also effectively inhibited PDAC cell invasion even when invasiveness was enhanced by administration of motility stimulators, such as nerve and neurosecretory factors. Moreover, noninvasive whole-body imaging analyses showed that OBP-702 significantly suppressed tumor growth in an orthotopic PDAC xenograft model, although both viruses were equally effective against subcutaneous tumors, suggesting that OBP-702 can influence the orthotopic tumor microenvironment. Our data suggest that oncolytic virus-mediated disruption of ERK signaling is a promising antitumor strategy for attenuating the invasiveness of PDAC cells.

Pancreatic Tumor Microenvironment

The pancreatic ductal adenocarcinoma (PDAC) microenvironment is a diverse and complex milieu of immune, stromal, and tumor cells and is characterized by a dense stroma, which mediates the interaction between the tumor and the immune system within the tumor microenvironment (TME). The interaction between stromal and tumor cells signals and shapes the immune infiltration of TME. The desmoplastic compartment contains infiltrated immune cells including tumor-associated macrophages (TAMs) and large numbers of fibroblasts/myofibroblasts dominated by pancreatic stellate cells (PSCs) which contribute to fibrosis. The highly fibrotic stroma with its extensive infiltration of immunosuppressive cells forms the major component of the pro-tumorigenic microenvironment (Laklai et al. Nat Med 22:497-505, 2016, Zhu et al. Cancer Res 74:5057-5069, 2014) provides a barrier to the delivery of cytotoxic agents and limits T-cell access to tumor cells (Feig et al. Proc Natl Acad Sci USA 110:20212-20217, 2013, Provenzano et al Cancer Cell 21:418-429, 2012). Activated PSCs reduced infiltration of cytotoxic T cells to the juxtatumoral stroma (immediately adjacent to the tumor epithelial cells) of PDAC (Ene-Obong et al. Gastroenterology 145:1121-1132, 2013). M1 macrophages activate an immune response against tumor, but M2 macrophages are involved in immunosuppression promoting tumor progression (Noy and Pollard Immunity 41:49-61, 2014, Ruffell et al. Trends Immunol 33:119-126, 2012). The desmoplastic stroma is reported to protect tumor cells against chemotherapies, promoting their proliferation and migration. However, experimental depletion of the desmoplastic stroma has led to more aggressive cancers in animal studies (Nielsen et al. World J Gastroenterol 22:2678-2700, 2016). Hence reprogramming rather than simple depletion of the PDAC stroma has the potential for developing new therapeutic strategies for PC treatment. Modulation of PSCs/fibrosis and immune infiltration/inflammation composes the major aspects of TME reprogramming.

Clinical impact of celiac ganglia metastasis upon pancreatic ductal adenocarcinoma

BACKGROUND

Pre-operative staging of pancreatic adenocarcinoma guides clinical decision making. Limited data indicate that metastasis to celiac ganglia (CG) correlates with poor prognosis. We investigated feasibility and safety of endoscopic ultrasound fine needle aspiration (EUS-FNA) detection of CG metastasis and its impact upon tumor stage, resectability, and survival in pancreatic ductal adenocarcinoma (PDAC).

PATIENTS

We reviewed our prospectively maintained EUS and cytopathology databases to identify patients with FNA proven CG metastasis in patients with PDAC from 2004 to 2017. Clinical demographics, EUS, CT, MRI, cytopathology, cancer stage, and resectability data were analyzed. Survival of PDAC patients with CG metastasis was compared to the expected survival of PDAC patients of similar stage as reported by the United States National Cancer Database.

RESULTS

Twenty-one patients with PDAC [median age 73 (IQR63-78); 14 (67%) female)], had CG metastasis confirmed by cytopathologic assessment. CG metastasis resulted in tumor upstaging relative to other EUS findings and cross sectional imaging findings in 12 (57%) and 15 (71%) patients, and converted cancers from resectable to unresectable relative to EUS and cross sectional imaging in 7 (37%) and 7 (37%) patients, respectively. In patients with PDAC, the survival of patients with CG metastasis was not significantly different from the overall survival (hazard ratio 0.71; 95% confidence interval 0.44, 1.13; p = 0.15).

CONCLUSIONS

EUS-FNA may safely identify CG metastases. While CG metastasis upstaged and altered the resectability status among this cohort of patients with PDAC, the survival data with regard to PDAC suggest that this may be misguided.

Pattern of Marginal Local Failure in a Phase II Trial of Neoadjuvant Chemotherapy and Stereotactic Body Radiation Therapy for Resectable and Borderline Resectable Pancreas Cancer

OBJECTIVES

The main objectives of this study were to prospectively evaluate the safety and efficacy of stereotactic body radiation therapy (SBRT) in the neoadjuvant setting for resectable or borderline resectable pancreatic cancer.

MATERIALS AND METHODS

Eighteen patients were enrolled from November 2014 to June 2017. Following 3 cycles of chemotherapy, SBRT was delivered to the tumor and abutting vessel and a 3 mm planning target volume (PTV) margin to 33 Gy (6.6 Gy×5) with an optional elective PTV to 25 Gy (5 Gy×5) customized to the nodal space and mesenteric vessels. The primary endpoint is ≥grade 3 acute and late gastrointestinal toxicity.

RESULTS

Fifteen patients had borderline resectable tumors due to arterial abutment (n=7) or superior mesenteric vein encasement (n=8); 3 patients had resectable tumors. There were no ≥grade 3 acute or late gastrointestinal events. Following SBRT, surgery was performed in 12 patients (67%) with 11 (92%) R0 resections. The median overall survival and progression-free survival was 21 months (95% CI: 18-29) and 11 months (95% CI: 8.4-16). Progression occurred in 83% (10/12) of resected patients (distant [n=4, 40%], local-only [n=4, 40%], and local and distant [n=2, 20%]). The cumulative incidence of local failure (LF) at 12 months from resection was 50% (95% CI: 20-80). All LF were outside to the PTV33.

CONCLUSIONS

Neoadjuvant SBRT was well tolerated, however LFs were predominantly observed outside the PTV33 volume that would have been covered with conventional RT volumes. The durability of local control after SBRT in the neoadjuvant setting merits examination relative to chemoradiation before incorporation into routine practice.