Cell-to-cell interaction analysis of prognostic ligand-receptor pairs in human pancreatic ductal adenocarcinoma

Cell-to-cell interactions (CCIs) through ligand-receptor (LR) pairs in the tumor microenvironment underlie the poor prognosis of pancreatic ductal adenocarcinoma (PDAC). However, there is scant knowledge of the association of CCIs with PDAC prognosis, which is critical to the identification of potential therapeutic candidates. Here, we sought to identify the LR pairs associated with PDAC patient prognosis by integrating survival analysis and single-cell CCI prediction. Via survival analysis using gene expression from cancer cohorts, we found 199 prognostic LR pairs. CCI prediction based on single-cell RNA-seq data revealed the enriched LR pairs associated with poor prognosis. Notably, the CCIs involved epithelial tumor cells, cancer-associated fibroblasts, and tumor-associated macrophages through integrin-related and ANXA1–FPR pairs. Finally, we determined that CCIs involving 33 poor-prognostic LR pairs were associated with tumor grade. Although the clinical implication of the set of LR pairs must be determined, our results may provide potential therapeutic targets in PDAC.     

Proteogenomic characterization of pancreatic ductal adenocarcinoma

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Acinar to ductal cell trans-differentiation: A prelude to dysplasia and pancreatic ductal adenocarcinoma

Pancreatic cancer (PC) is the deadliest neoplastic epithelial malignancies and is projected to be the second leading cause of cancer-related mortality by 2024. Five years overall survival being ~10%, mortality and incidence rates are disturbing. Acinar to ductal cell metaplasia (ADM) encompasses cellular reprogramming and phenotypic switch-over, making it a cardinal event in tumor initiation. Differential cues and varied regulatory factors drive synchronous functions of metaplastic cell populations leading to multiple cell fates and physiological outcomes. ADM is a precursor for developing early pre-neoplastic lesions further progressing into PC due to oncogenic signaling. Hence delineating molecular events guiding tumor initiation may provide cues for regenerative medicine and precision onco-medicine. Therefore, understanding PC pathogenesis and early diagnosis are crucial. We hereby provide a timely overview of the current progress in this direction and future perspectives we foresee unfolding in the best interest of patient well-being and better clinical management of PC.     

Autoantibody signature in human ductal pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy characterized by rapid progression, invasiveness, and resistance to treatment. It is the fourth leading cause of cancer death with a 2% 5-year survival rate. Biomarkers for its early detection are lacking. This study was designed to use a proteomics-based approach as a means of identifying antigens that elicit a humoral response in PDAC patients. Antibodies against PDAC-associated antigens are useful for early cancer diagnosis and therapy. Proteins from PDAC cell lines were separated by 2-DE, and the serum IgG reactivity of 70 PDAC patients, 40 healthy subjects (HS), 30 non-PDAC tumor patients, and 15 chronic pancreatitis (CP) patients was tested by Western blot analysis. Spots specifically recognized by PDAC sera and revealed by mass spectrometry corresponded to metabolic enzymes or cytoskeletal proteins. Most were up-regulated in PDAC tissues. Thus, it seems that metabolic enzymes and cytoskeletal proteins are specific targets of the humoral response during PDAC. The results of further studies of these serological-defined antigens could be of diagnostic and therapeutic significance in PDAC.     

Fibroblast heterogeneity in pancreatic ductal adenocarcinoma: Perspectives in immunotherapy

Cancer-associated fibroblasts (CAFs), the key component in pancreatic tumor microenvironment (TME), originate from many sources and are naturally heterogeneous in phenotype and function. Numerous studies have identified their crucial role in promoting tumorigenesis through many routes including fostering cancer proliferation, angiogenesis, invasion, and metastasis. Conversely, research also indicates that subsets of CAFs express anti-tumor activity. These dual effects reflect the complexity of CAF heterogeneity and their interactions with other cells and factors in pancreatic TME. A critical component in this environment is infiltrated immune cells and immune mediators, which can communicate with CAFs. The crosstalk occurs via the production of various cytokines, chemokines, and other mediators and shapes the immunological state in TME. Comprehensive studies of the crosstalk between CAFs and tumor immune environment, particularly internal mechanisms interlinking CAFs and immune effectors, may provide new approaches for pancreatic ductal adenocarcinoma (PDAC) treatments. In this review, we explore the characteristics of CAFs, describe the interplay among CAFs, infiltrated immune cells, other mediators, and provide an overview of recent CAF-target therapies, their limitations, and potential research directions in CAF in the context of PDAC.     

Targeted nanoparticles for imaging incipient pancreatic ductal adenocarcinoma

Background

Pancreatic ductal adenocarcinoma (PDAC) carries an extremely poor prognosis, typically presenting with metastasis at the time of diagnosis and exhibiting profound resistance to existing therapies. The development of molecular markers and imaging probes for incipient PDAC would enable earlier detection and guide the development of interventive therapies. Here we sought to identify novel molecular markers and to test their potential as targeted imaging agents.

Methods and Findings

Here, a phage display approach was used in a mouse model of PDAC to screen for peptides that specifically bind to cell surface antigens on PDAC cells. These screens yielded a motif that distinguishes PDAC cells from normal pancreatic duct cells in vitro, which, upon proteomics analysis, identified plectin-1 as a novel biomarker of PDAC. To assess their utility for in vivo imaging, the plectin-1 targeted peptides (PTP) were conjugated to magnetofluorescent nanoparticles. In conjunction with intravital confocal microscopy and MRI, these nanoparticles enabled detection of small PDAC and precursor lesions in engineered mouse models.

Conclusions

Our approach exploited a well-defined model of PDAC, enabling rapid identification and validation of PTP. The developed specific imaging probe, along with the discovery of plectin-1 as a novel biomarker, may have clinical utility in the diagnosis and management of PDAC in humans.     

Microvascular density in chronic pancreatitis and pancreatic ductal adenocarcinoma

Chronic pancreatitis and pancreatic adenocarcinoma represent two pathologic phenomena with marked production of connective tissue stroma containing numerous small blood vessels. The aim of this study was to characterise quantitatively the vascular supply of pancreatic adenocarcinoma and fragments of the periductal tissue collected from patients with chronic pancreatitis. The study material included 18 cases of pancreatitis and 22 cases of pancreatic ductal adenocarcinoma. Microvessels were marked using monoclonal anti-CD34 antibodies. The number of blood vessels in the fibrous stroma was significantly higher in the chronic pancreatitis samples compared to the pancreatic carcinoma group (mean vessel count 298 and 194 vessel/mm2; median 251 and 187 vessel/mm2 respectively; p<0.01). Distributions of the vascular diameter in both studied groups were very similar. The obtained results suggest that the development of vascular network accompanying chronic pancreatitis is more effective in some parts of pancreas compared to angiogenic intensity in pancreatic adenocarcinoma.     

Stem cells as the root of pancreatic ductal adenocarcinoma

Emerging evidence suggests that stem cells play a crucial role not only in the generation and maintenance of different tissues, but also in the development and progression of malignancies. For the many solid cancers, it has now been shown that they harbor a distinct subpopulation of cancer cells that bear stem cell features and therefore, these cells are termed cancer stem cells (CSC) or tumor-propagating cells. CSC are exclusively tumorigenic and essential drivers for tumor progression and metastasis. Moreover, it has been shown that pancreatic ductal adenocarcinoma does not only contain one homogeneous population of CSC rather than diverse subpopulations that may have evolved during tumor progression. One of these populations is called migrating CSC and can be characterized by CXCR4 co-expression. Only these cells are capable of evading the primary tumor and traveling to distant sites such as the liver as the preferred site of metastatic spread. Clinically even more important, however, is the observation that CSC are highly resistant to chemo- and radiotherapy resulting in their relative enrichment during treatment and rapid relapse of disease. Many laboratories are now working on the further in-depth characterization of these cells, which may eventually allow for the identification of their Achilles heal and lead to novel treatment modalities for fighting this deadly disease.     

Angiogenesis and p53 and H-ras mutations in pancreatic ductal adenocarcinoma

OBJECTIVE: To evaluate the correlation of angiogenesis and p53 and H-ras mutations with prognostic factors and proliferative activity assessed with Ki-67 protein expression by studying archival tissues from 24 patients with primary pancreatic ductal adenocarcinoma. STUDY DESIGN: Vascular structures were labeled immunohistochemically using factor VIII-related antigen. Vascular surface density (VSD) and microvessel number (NVES) were assessed by stereology. The tissues were also analyzed with the immunohistochemical method for the expression of proteins, including p53, H-ras and Ki-67. RESULTS: Statistical analysis revealed that tumors with greater NVES and VSD values significantly correlated with occurrence of metastases, higher proliferative activity, poorer histologic differentiation and greater tumor size. p53 Mutations were found in 11 cases (45.8%). However, only three cases (12.5%), all negative for p53 mutations, showed H-ras mutations. p53 Mutation-positive tumors exhibited a statistically significant correlation with occurrence of metastases and higher proliferative activity, whereas H-ras mutations did not show such a correlation. CONCLUSION: Angiogenesis might have a role in predicting prognosis in pancreatic carcinomas, and p53 mutations might be acquired in later stages associated with metastatic progression and higher proliferative activity. Although H-ras mutations were rare in the present study, they might play a role in a different carcinogenic pathway excluding p53 mutations.     

Phosphoproteomics guides effective low-dose drug combinations against pancreatic ductal adenocarcinoma

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miR-545 inhibited pancreatic ductal adenocarcinoma growth by targeting RIG-I

Pancreatic ductal adenocarcinoma (PDAC) ranks fourth on the list of cancer-related causes of death. Deregulation or dysfunction of miRNAs contribute to cancer development. In this study, we found that low miR-545 level and high RIG-I protein in PDAC tissues were both correlated with low survival rate. MiR-545 up-regulation inhibited PDAC cell lines growth and vice versa. 3′UTR of RIG-I was targeted by miR-545. Thus we concluded that low miR-545 levels in PDAC promote tumor cells growth, and this is associated with reduced survival in PDAC patients. MiR-545 exerts its effects by directly targeting RIG-1.     

Analysis of dynamic molecular networks for pancreatic ductal adenocarcinoma progression

Background

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest solid tumors. The rapid progression of PDAC results in an advanced stage of patients when diagnosed. However, the dynamic molecular mechanism underlying PDAC progression remains far from clear.

Methods

The microarray GSE62165 containing PDAC staging samples was obtained from Gene Expression Omnibus and the differentially expressed genes (DEGs) between normal tissue and PDAC of different stages were profiled using R software, respectively. The software program Short Time-series Expression Miner was applied to cluster, compare, and visualize gene expression differences between PDAC stages. Then, function annotation and pathway enrichment of DEGs were conducted by Database for Annotation Visualization and Integrated Discovery. Further, the Cytoscape plugin DyNetViewer was applied to construct the dynamic protein–protein interaction networks and to analyze different topological variation of nodes and clusters over time. The phosphosite markers of stage-specific protein kinases were predicted by PhosphoSitePlus database. Moreover, survival analysis of candidate genes and pathways was performed by Kaplan–Meier plotter. Finally, candidate genes were validated by immunohistochemistry in PDAC tissues.

Results

Compared with normal tissues, the total DEGs number for each PDAC stage were 994 (stage I), 967 (stage IIa), 965 (stage IIb), 1027 (stage III), 925 (stage IV), respectively. The stage-course gene expression analysis showed that 30 distinct expressional models were clustered. Kyoto Encyclopedia of Genes and Genomes analysis indicated that the up-regulated DEGs were commonly enriched in five fundamental pathways throughout five stages, including pathways in cancer, small cell lung cancer, ECM-receptor interaction, amoebiasis, focal adhesion. Except for amoebiasis, these pathways were associated with poor PDAC overall survival. Meanwhile, LAMA3, LAMB3, LAMC2, COL4A1 and FN1 were commonly shared by these five pathways and were unfavorable factors for prognosis. Furthermore, by constructing the stage-course dynamic protein interaction network, 45 functional molecular modules and 19 nodes were identified as featured regulators for all PDAC stages, among which the collagen family and integrins were considered as two main regulators for facilitating aggressive progression. Additionally, the clinical relevance analysis suggested that the stage IV featured nodes MLF1IP and ITGB4 were significantly correlated with shorter overall survival. Moreover, 15 stage-specific protein kinases were identified from the dynamic network and CHEK1 was particularly activated at stage IV. Experimental validation showed that MLF1IP, LAMA3 and LAMB3 were progressively increased from tumor initiation to progression.

Conclusions

Our study provided a view for a better understanding of the dynamic landscape of molecular interaction networks during PDAC progression and offered potential targets for therapeutic intervention.

     

Non-coding RNAs in pancreatic ductal adenocarcinoma: New approaches for better diagnosis and therapy

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies with a 5-year survival rate less than 8%, which has remained unchanged over the last 50 years. Early detection is particularly difficult due to the lack of disease-specific symptoms and a reliable biomarker. Multimodality treatment including chemotherapy, radiotherapy (used sparingly) and surgery has become the standard of care for patients with PDAC. Carbohydrate antigen 19–9 (CA 19–9) is the most common diagnostic biomarker; however, it is not specific enough especially for asymptomatic patients. Non-coding RNAs are often deregulated in human malignancies and shown to be involved in cancer-related mechanisms such as cell growth, differentiation, and cell death. Several micro, long non-coding and circular RNAs have been reported to date which are involved in PDAC. Aim of this review is to discuss the roles and functions of non-coding RNAs in diagnosis and treatments of PDAC.     

SIRT1 and circadian gene expression in pancreatic ductal adenocarcinoma: Effect of starvation

Pancreatic cancer (PC), the fourth leading cause of cancer-related deaths, is characterized by high aggressiveness and resistance to chemotherapy. Pancreatic carcinogenesis is kept going by derangement of essential cell processes, such as proliferation, apoptosis, metabolism and autophagy, characterized by rhythmic variations with 24-h periodicity driven by the biological clock. We assessed the expression of the circadian genes ARNLT, ARNLT2, CLOCK, PER1, PER2, PER3, CRY1, CRY2 and the starvation-activated histone/protein deacetylase SIRT1 in 34 matched tumor and non-tumor tissue specimens of PC patients, and evaluated in PC derived cell lines if the modulation of SIRT1 expression through starvation could influence the temporal pattern of expression of the circadian genes. We found a significant down-regulation of ARNLT (p?=?0.015), CRY1 (p?=?0.013), CRY2 (p?=?0.001), PER1 (p?<?0.0001), PER2 (p?<?0.001), PER3 (p?=?0.001) and SIRT1 (p?=?0.017) in PC specimens. PER3 and CRY2 expression levels were lower in patients with jaundice at diagnosis (?<?0.05). Having adjusted for age, adjuvant therapy and tumor stage, we evidenced that patients with higher PER2 and lower SIRT1 expression levels showed lower mortality (p?=?0.028). Levels and temporal patterns of expression of many circadian genes and SIRT1 significantly changed upon serum starvation in vitro, with differences among four different PC cell lines examined (BXPC3, CFPAC, MIA-PaCa-2 and PANC-1). Serum deprivation induced changes of the overall mean level of the wave and amplitude, lengthened or shortened the cycle time and phase-advanced or phase-delayed the rhythmic oscillation depending on the gene and the PC cell line examined. In conclusion, a severe deregulation of expression of SIRT1 and circadian genes was evidenced in the cancer specimens of PC patients, and starvation influenced gene expression in PC cell lines, suggesting that the altered interplay between SIRT1 and the core circadian proteins could represent a crucial player in the process of pancreatic carcinogenesis.