CD74 promotes perineural invasion of cancer cells and mediates neuroplasticity via the AKT/EGR-1/GDNF axis in pancreatic ductal adenocarcinoma

Tumor microenvironment (Part I): Tissue integrity in a rat model of peripheral neural cancer

ICAM-1 (intercellular adhesion molecule 1) and MPZ (myelin protein zero) are thought to be a factor in the integrity of nerve tissues. In this report, we attempted to trace the expression of ICAM-1, responsible for cell-to-cell adhesion, and of MPZ, the main constituent of myelin sheath, in malignant tissues of the sciatic nerve (SN) in inbred male Copenhagen rats. AT-1 Cells (anaplastic tumor 1) were injected in the perineurial sheath, and tissues of the SNs were collected after 7, 14 and 21 days and compared to a sham-operated group of rats (n = 6 each). Tissues were sectioned and histologically examined, under light microscope, and stained for measuring the immunoreactivity of ICAM-1 and MPZ under laser scanning microscope. The cancer model was established, and the tumor growth was confirmed. ICAM-1 showed severe decreases, proportional to the growing anaplastic cells, as compared to the sham group. MPZ revealed, however, a distinct defensive pattern before substantially decreasing in a comparison with sham. These results support the notion that malignancies damage peripheral nerves and cause severe axonal injury and loss of neuronal integrity, and clearly define the role of ICAM-1 and MPZ in safeguarding the nerve tissues.

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.

Identification of cells of leukemic stem cell origin with non-canonical regenerative properties

Despite most acute myeloid leukemia (AML) patients entering remission following chemotherapy, outcomes remain poor due to surviving leukemic cells that contribute to relapse. The nature of these enduring cells is poorly understood. Here, through temporal single-cell transcriptomic characterization of AML hierarchical regeneration in response to chemotherapy, we reveal a cell population: AML regeneration enriched cells (RECs). RECs are defined by CD74/CD68 expression, and although derived from leukemic stem cells (LSCs), are devoid of stem/progenitor capacity. Based on REC in situ proximity to CD34-expressing cells identified using spatial transcriptomics on AML patient bone marrow samples, RECs demonstrate the ability to augment or reduce leukemic regeneration in vivo based on transfusion or depletion, respectively. Furthermore, RECs are prognostic for patient survival as well as predictive of treatment failure in AML cohorts. Our study reveals RECs as a previously unknown functional catalyst of LSC-driven regeneration contributing to the non-canonical framework of AML regeneration.

The depth of perineural invasion is an independent prognostic factor for stage II colorectal cancer

BACKGROUND

Perineural invasion (PNI) is the invasion of nerves by cancer cells and is associated with poor survival in stage II colorectal cancer. However, PNI can be further subdivided according to the depth of invasion, and the depth of PNI has not been clearly linked to prognosis.

METHOD

This study aimed to assess the prognostic value of different depths of PNI in stage II colorectal cancer. We defined PNI in the submucosal plexus and myenteric plexus as superficial perineural invasion (sup-PNI) and PNI in the subserous plexus as deep perineural invasion (deep-PNI). Patients were divided into three groups based on the depth of PNI: sup-PNI, deep-PNI and non-PNI. Then, univariate and multivariate Cox regression analyses were conducted to evaluate the role of PNI in the prognosis of stage II colorectal cancer.

RESULTS

This study enrolled 3508 patients with stage II colorectal cancer who underwent resection for primary colorectal lesions between January 2013 and September 2019. Clinicopathological features, including elevated carcinoembryonic antigen (CEA) levels, T4 stage, poor differentiation, deficient DNA mismatch repair (dMMR), and vascular invasion, were correlated with deep-PNI. Multivariate analyses revealed that deep-PNI was associated with worse overall survival (OS; hazard ratio [HR], 3.546; 95% confidence interval [CI], 2.307-5.449; P < 0.001) and disease-free survival (DFS; HR, 2.921; 95% CI, 2.032-4.198; P < 0.001), compared with non-PNI. Conversely, no significant difference in OS or DFS was observed between the sup-PNI and non-PNI groups in multivariate analyses.

CONCLUSIONS

The study demonstrated that the depth of PNI was an independent prognostic factor for patients with stage II colorectal cancer, and patients with deep PNI had a worse prognosis. Thus, patients with PNI require further subdivision according to the depth of invasion.

Dickkopf-1 drives perineural invasion via PI3K-AKT signaling pathway in head and neck squamous cancer

Perineural invasion (PNI) leads to the poor prognosis of head and neck squamous cancer (HNSCC) patients, but the mechanism of PNI remains unclear. Dickkopf-1 (DKK1), a secretory protein in the Wnt signaling pathway, was found indeed upregulated in HNSCC cells and tissues. Higher expression of DKK1 was statistically relevant to T stage, N stage, PNI, and poor prognosis of HNSCC. DKK1 overexpression enhanced the migration abilities of cancer cells. Moreover, DKK1-overexpressing cancer cells promoted cancer cells invasion of peripheral nerves in vitro and in vivo. Mechanistically, DKK1 could promote the PI3K-AKT signaling pathway. The migration abilities of neuroblastoma cells, which were enhanced by DKK1-overexpressing HNSCC cell lines, could be reversed by an inhibitor of Akt (MK2206). The association of DKK1 with PNI was also confirmed in HNSCC samples. Variables, including T stage, N stage, DKK1 expression, and PNI, were used to establish a nomogram to predict the survival probability and disease-free probability at 3 and 5 years. In summary, DKK1 can promote the PI3K-AKT signaling pathway in tumor cells and then could induce neuritogenesis and facilitate PNI. MK2206 may be a potential therapeutic target drug for HNSCC patients with PNI.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Expression of early growth responsive gene-1 in the lateral geniculate body of kittens with amblyopia caused by monocular form deprivation

OBJECTIVE

The expression of early growth responsive gene-1 (Egr-1) in the lateral geniculate body in the normal kittens and those affected with amblyopia caused by monocular visual deprivation was compared to explore the potential significance of Egr-1 in the pathogenesis of amblyopia.

METHODS

A total of 30 healthy kittens were equally and randomly divided into the control (n = 15) and the deprivation group (n = 15). The kittens were raised in natural light and the right eyes of the deprived kittens were covered with a black opaque covering. Pattern visual evoked potential (PVEP) was measured before and 1, 3, and 5 weeks after covering. Five kittens from each group were randomly selected and euthanized with 2% sodium pentobarbital (100 mg/kg) during the 1st, 3rd and 5th week after covering. The expression of Egr-1 in the lateral geniculate body in the two groups was compared by performing immunohistochemistry and in situ hybridization.

RESULTS

After three weeks of covering, PVEP detection indicated that the P100 wave latency in the deprivation group was significantly higher than that in the control group (P < 0.05), whereas the amplitude decreased markedly (P < 0.05). The number of the positive cells (P < 0.05) and mean optical density (P < 0.05) of Egr-1 protein expression in the lateral geniculate body of the deprivation group were found to be substantially lower in comparison to the normal group, as well as the number (P < 0.05) and mean optical density of Egr-1 mRNA-positive cells (P < 0.05). However, with increase of age, positive expression of Egr-1 in the control group showed an upward trend (P < 0.05), but this trend was not noted in the deprivation group (P > 0.05).

CONCLUSIONS

Monocular form deprivation can lead to substantially decreased expressions of Egr-1 protein and mRNA in the lateral geniculate body, which in turn can affect the normal expression of neuronal functions in the lateral geniculate body, thereby promoting the occurrence and development of amblyopia.

FABP6 serves as a new therapeutic target in esophageal tumor

BACKGROUND

Esophageal cancer is one of the most common malignant tumors with high incidence and mortality rates. Despite the continuous development of treatment options, the prognosis for esophageal cancer patients remains poor. Therefore, there is an urgent need for new diagnostic and therapeutic targets in clinical practice to improve the survival of patients with esophageal cancer.

METHODS

In this study, we conducted a comprehensive scRNA-seq analysis of the tumor microenvironment in primary esophageal tumors to elucidate cell composition and heterogeneity. Using Seurat, we identified eight clusters, encompassing non-immune cells (fibroblasts, myofibroblasts, endothelial cells, and epithelial cells) and immunocytes (myeloid-derived cells, T cells, B cells, and plasma cells). Compared to normal tissues, tumors exhibited an increased proportion of epithelial cells and alterations in immune cell infiltration. Analysis of epithelial cells revealed a cluster (cluster 0) with a high differentiation score and early distribution, suggesting its importance as a precursor cell.

RESULTS

Cluster 0 was characterized by high expression of FABP6, indicating a potential role in fatty acid metabolism and tumor growth. T cell analysis revealed shifts in the balance between Treg and CD8+ effector T cells in tumor tissues. Cellular communication analysis identified increased interactions between FABP6+ tumor cells and T cells, with the involvement of the MIF-related pathway and the CD74-CD44 interaction. This study provides insights into the cellular landscape and immune interactions within esophageal tumors, contributing to a better understanding of tumor heterogeneity and potential therapeutic targets.

Comprehensive Analysis Reveals Prognostic and Therapeutic Immunity-Related Biomarkers for Pediatric Metastatic Osteosarcoma

Background and Objectives: Osteosarcoma, the most prevalent malignant bone tumor in children and adolescents, presents a complex pathogenesis characterized by various genetic and epigenetic alterations. This study aims to identify key differentially expressed genes (DEGs) in pediatric osteosarcoma, with a focus on those influencing metastasis and patient survival. Materials and Methods: We utilized the GSE33382 dataset from the GEO database for a comprehensive bioinformatic analysis. This included a protein-protein interaction (PPI) network analysis, Cox regression, and Kaplan-Meier survival analysis to identify central DEGs associated with osteosarcoma metastasis and patient survival. Results: Our analysis identified 88 DEGs related to osteosarcoma metastasis. Among them, three survival-related central DEGs-C1QA, CD74, and HLA-DMA-were significantly linked to patient outcomes. Further correlation analysis established a strong relationship between these genes, tumor mutation burden (TMB), immune checkpoint gene expression, and overall survival. Notably, C1QA and CD74 exhibited higher expression in non-metastatic osteosarcoma cases, suggesting a potential role in disease progression. Conclusions: The identified DEGs, particularly C1QA, CD74, and HLA-DMA, may serve as critical biomarkers for pediatric osteosarcoma prognosis and potential targets for immunotherapy. These findings provide a deeper understanding of the molecular landscape of osteosarcoma and open new avenues for therapeutic intervention.

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.

Crosstalk Between Peripheral Innervation and Pancreatic Ductal Adenocarcinoma

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

Integrated analysis of single-cell and bulk RNA-sequencing data reveals the prognostic value and molecular function of THSD7A in gastric cancer

The biological role and prognostic value of thrombospondin domain-containing 7A (THSD7A) in gastric cancer remain unclear. Our purpose was to determine the molecular mechanisms underlying the functioning of THSD7A and its prognostic value in gastric cancer. Gastric cancer-associated single cell and bulk RNA sequencing data obtained from two databases, were analyzed. We used bulk RNA sequencing to examine the differential expression of THSD7A in gastric cancer and normal gastric tissues and explored the relationship between THSD7A expression and clinicopathological characteristics. Kaplan-Meier survival and Cox analyses revealed the prognostic value of THSD7A. Gene set enrichment and immune infiltration analyses were used to determine the cancer-promoting mechanisms of THSD7A and its effect on the immune microenvironment. We explored the relationship between THSD7A expression and sensitivity of anti-tumor drugs and immune checkpoint levels. Biological functions of THSD7A were validated at single-cell and in vitro levels. THSD7A expression was significantly increased in gastric cancer samples. High THSD7A expression was associated with poor clinical phenotypes and prognoses. Cox analysis showed that THSD7A was an independent risk factor for patients with gastric cancer. Enrichment analysis suggested that epithelial-mesenchymal transition and inflammatory responses may be potential pro-cancer mechanisms of THSD7A. Upregulation of THSD7A promoted infiltration by M2 macrophages and regulatory T cells. High THSD7A expression suppressed the sensitivity of patients with gastric cancer to drugs, such as 5-fluorouracil, bleomycin, and cisplatin, and upregulated immune checkpoints, such as HAVCR2, PDCD1LG2, TIGIT, and CTLA4. At the single cell level, THSD7A was an endothelial cell-associated gene and endothelial cells overexpressing THSD7A showed unique pro-oncogenic effects. In vitro experiments confirmed that THSD7A was overexpressed in gastric cancer samples and cells, and that knocking out THSD7A significantly inhibited gastric cancer cell proliferation and invasion. THSD7A overexpression may be a unique prognostic marker and therapeutic target in gastric cancer. Therefore, our study provides a new perspective on the precise treatment of gastric cancer.

Unraveling the Mysteries of Perineural Invasion in Benign and Malignant Conditions

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

Spatial Transcriptomics of Intraductal Papillary Mucinous Neoplasms of the Pancreas Identifies NKX6-2 as a Driver of Gastric Differentiation and Indolent Biological Potential

Intraductal papillary mucinous neoplasms (IPMN) of the pancreas are bona fide precursor lesions of pancreatic ductal adenocarcinoma (PDAC). The most common subtype of IPMNs harbors a gastric foveolar-type epithelium, and these low-grade mucinous neoplasms are harbingers of IPMNs with high-grade dysplasia and cancer. The molecular underpinning of gastric differentiation in IPMNs is unknown, although identifying drivers of this indolent phenotype might enable opportunities for intercepting progression to high-grade IPMN and cancer. We conducted spatial transcriptomics on a cohort of IPMNs, followed by orthogonal and cross-species validation studies, which established the transcription factor NKX6-2 as a key determinant of gastric cell identity in low-grade IPMNs. Loss of NKX6-2 expression is a consistent feature of IPMN progression, while reexpression of Nkx6-2 in murine IPMN lines recapitulates the aforementioned gastric transcriptional program and glandular morphology. Our study identifies NKX6-2 as a previously unknown transcription factor driving indolent gastric differentiation in IPMN pathogenesis.

SIGNIFICANCE

Identification of the molecular features driving IPMN development and differentiation is critical to prevent cancer progression and enhance risk stratification. We used spatial profiling to characterize the epithelium and microenvironment of IPMN, which revealed a previously unknown link between NKX6-2 and gastric differentiation, the latter associated with indolent biological potential. See related commentary by Ben-Shmuel and Scherz-Shouval, p. 1768. This article is highlighted in the In This Issue feature, p. 1749.

CD51 Intracellular Domain Promotes Cancer Cell Neurotropism through Interacting with Transcription Factor NR4A3 in Colorectal Cancer

The abundant nervous system in intestine provides the basis for perineural invasion (PNI) of colorectal cancer (CRC). PNI is defined as the invasion of the nerves by cancer cells. Although PNI is already known to be an independent prognostic factor in CRC, the molecular mechanism underlying PNI remains obscure. In this study, we first demonstrated that CD51 could promote the neurotropism of tumor cells through cleavage with γ-secretase to generate an intracellular domain (ICD). Mechanistically, ICD of CD51 could bind to the transcription factor NR4A3, and act as a coactivator to promote the expression of downstream effectors, such as NTRK1, NTRK3, and SEMA3E. Pharmacological inhibition of γ-secretase impedes PNI mediated by CD51 in CRC both in vitro and in vivo and may become a potential therapeutic target for PNI in CRC.

MLK3 Regulates Inflammatory Response via Activation of AP-1 Pathway in HEK293 and RAW264.7 Cells

Inflammation is a critically important barrier found in innate immunity. However, severe and sustained inflammatory conditions are regarded as causes of many different serious diseases, such as cancer, atherosclerosis, and diabetes. Although numerous studies have addressed how inflammatory responses proceed and what kinds of proteins and cells are involved, the exact mechanism and protein components regulating inflammatory reactions are not fully understood. In this paper, to determine the regulatory role of mixed lineage kinase 3 (MLK3), which functions as mitogen-activated protein kinase kinase kinase (MAP3K) in cancer cells in inflammatory response to macrophages, we employed an overexpression strategy with MLK3 in HEK293 cells and used its inhibitor URMC-099 in lipopolysaccharide (LPS)-treated RAW264.7 cells. It was found that overexpressed MLK3 increased the mRNA expression of inflammatory genes (COX-2, IL-6, and TNF-α) via the activation of AP-1, according to a luciferase assay carried out with AP-1-Luc. Overexpression of MLK3 also induced phosphorylation of MAPKK (MEK1/2, MKK3/6, and MKK4/7), MAPK (ERK, p38, and JNK), and AP-1 subunits (c-Jun, c-Fos, and FRA-1). Phosphorylation of MLK3 was also observed in RAW264.7 cells stimulated by LPS, Pam3CSK, and poly(I:C). Finally, inhibition of MLK3 by URMC-099 reduced the expression of COX-2 and CCL-12, phosphorylation of c-Jun, luciferase activity mediated by AP-1, and phosphorylation of MAPK in LPS-treated RAW264.7 cells. Taken together, our findings strongly suggest that MLK3 plays a central role in controlling AP-1-mediated inflammatory responses in macrophages and that this enzyme can serve as a target molecule for treating AP-1-mediated inflammatory diseases.

Perineural invasion-associated biomarkers for tumor development

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

NK cell-mediated immunostimulatory effects of ethanol extract of Morinda citrifolia (noni) fruit

Background

Morinda citrifolia (Noni) is a plant that has long been used in various products such as foods and cosmetics. Although noni has been known to have immunostimulatory activity, detailed mechanism at the cellular level has not been fully elucidated yet. In this study, we focused on understanding as to how noni fruit can positively stimulate body’s immune responses.

Methods

To do this, an ethanol extract of noni fruit (Mc-fEE) was prepared and administered for 30 days to male C57BL/6 mice for in vivo experiment. NK cell activity and cytokine production level from Mc-fEE-treated mice were analyzed by flowcytometry, real-time PCR, and ELISA. Mc-fEE-triggered molecular events were detected from RAW264.7 cells and splenocytes using Western blotting and real-time PCR analyses.

Results

The mRNA expression levels of cytokines such as interleukin families, interferon (IFN)-β, and tumor necrosis factor (TNF)-α were increased by Mc-fEE treatment in vitro and in vivo. Western blotting analysis showed that the phosphorylation levels of nuclear factor (NF)-κB and activator protein (AP)-1 subunits these were enhanced in Mc-fEE-treated RAW264.7 cells. In addition, according to in vivo experiments, it was considered that Mc-fEE can increase the population of splenic NK cells and subsequent upregulation of their cytotoxic activity against YAC-1 cells, a T- cell lymphoma.

Conclusion

In this paper, we could confirm that Mc-fEE has remarkable immunostimulatory effects by activation and increase of the NK cell population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03700-3.

In Vitro Human Cancer Models for Biomedical Applications

Simple Summary

Cancer is a leading cause of death worldwide. While numerous studies have been conducted on cancer treatment, clinical treatment options for cancers are still limited. To date, animal cancer models for cancer therapeutic studies have faced multiple challenges, including inaccuracy in the representation of human cancers, high cost and ethical concerns. Therefore, lab-grown human cancer models are being developed quickly to fulfill the increasing demand for more relevant models in order to improve knowledge of human cancers and to find novel treatments. This review summarizes the development of lab-grown human cancer models for biomedical applications, including cancer therapeutic development, assessment of human tumor biology and discovery of key cancer markers.

Abstract

Cancer is one of the leading causes of death worldwide, and its incidence is steadily increasing. Although years of research have been conducted on cancer treatment, clinical treatment options for cancers are still limited. Animal cancer models have been widely used for studies of cancer therapeutics, but these models have been associated with many concerns, including inaccuracy in the representation of human cancers, high cost and ethical issues. Therefore, in vitro human cancer models are being developed quickly to fulfill the increasing demand for more relevant models in order to get a better knowledge of human cancers and to find novel treatments. This review summarizes the development of in vitro human cancer models for biomedical applications. We first review the latest development in the field by detailing various types of in vitro human cancer models, including transwell-based models, tumor spheroids, microfluidic tumor-microvascular systems and scaffold-based models. The advantages and limitations of each model, as well as their biomedical applications, are summarized, including therapeutic development, assessment of tumor cell migration, metastasis and invasion and discovery of key cancer markers. Finally, the existing challenges and future perspectives are briefly discussed.

Emerging experimental models for assessing perineural invasion in human cancers

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

Schwann Cells in Digestive System Disorders

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

Master Regulators of Epithelial-Mesenchymal Transition and WNT Signaling Pathways in Juvenile Nasopharyngeal Angiofibromas

Juvenile nasopharyngeal angiofibroma (JNA) is a rare fibrovascular benign tumor showing an invasive growth pattern and affecting mainly male adolescents. We investigated the role of epithelial–mesenchymal transition (EMT) and WNT signaling pathways in JNA. Gene expression profiles using nine JNA paired with four inferior nasal turbinate samples were interrogated using a customized 2.3K microarray platform containing genes mainly involved in EMT and WNT/PI3K pathways. The expression of selected genes (BCL2, CAV1, CD74, COL4A2, FZD7, ING1, LAMB1, and RAC2) and proteins (BCL2, CAV1, CD74, FZD7, RAF1, WNT5A, and WNT5B) was investigated by RT-qPCR (28 cases) and immunohistochemistry (40 cases), respectively. Among 104 differentially expressed genes, we found a significantly increased expression of COL4A2 and LAMB1 and a decreased expression of BCL2 and RAC2 by RT-qPCR. The immunohistochemistry analysis revealed a low expression of BCL2 and a negative to moderate expression of FZD7 in most samples, while increased CAV1 and RAF1 expression were detected. Moderate to strong CD74 protein expression was observed in endothelial and inflammatory cells. A significant number of JNAs (78%) presented reduced WNT5A and increased WNT5B expression. Overall, the transcript and protein profile indicated the involvement of EMT and WNT pathways in JNA. These candidates are promising druggable targets for treating JNA.

Modeling pancreatic cancer in mice for experimental therapeutics

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy that is characterized by early metastasis, low resectability, high recurrence, and therapy resistance. The experimental mouse models have played a central role in understanding the pathobiology of PDAC and in the preclinical evaluation of various therapeutic modalities. Different mouse models with targetable pathological hallmarks have been developed and employed to address the unique challenges associated with PDAC progression, metastasis, and stromal heterogeneity. Over the years, mouse models have evolved from simple cell line-based heterotopic and orthotopic xenografts in immunocompromised mice to more complex and realistic genetically engineered mouse models (GEMMs) involving multi-gene manipulations. The GEMMs, mostly driven by KRAS mutation(s), have been widely accepted for therapeutic optimization due to their high penetrance and ability to recapitulate the histological, molecular, and pathological hallmarks of human PDAC, including comparable precursor lesions, extensive metastasis, desmoplasia, perineural invasion, and immunosuppressive tumor microenvironment. Advanced GEMMs modified to express fluorescent proteins have allowed cell lineage tracing to provide novel insights and a new understanding about the origin and contribution of various cell types in PDAC pathobiology. The syngeneic mouse models, GEMMs, and target-specific transgenic mice have been extensively used to evaluate immunotherapies and study therapy-induced immune modulation in PDAC yielding meaningful results to guide various clinical trials. The emerging mouse models for parabiosis, hepatic metastasis, cachexia, and image-guided implantation, are increasingly appreciated for their high translational significance. In this article, we describe the contribution of various experimental mouse models to the current understanding of PDAC pathobiology and their utility in evaluating and optimizing therapeutic modalities for this lethal malignancy.