Evaluation of cell-free DNA as a biomarker for pancreatic malignancies

Clinical Application of Liquid Biopsy in Pancreatic Cancer: A Narrative Review

Pancreatic ductal adenocarcinoma contributes significantly to global cancer-related deaths, featuring only a 10% survival rate over five years. The quest for novel tumor markers is critical to facilitate early diagnosis and tailor treatment strategies for this disease, which is key to improving patient outcomes. In pancreatic ductal adenocarcinoma, these markers have been demonstrated to play a crucial role in early identification, continuous monitoring, and prediction of its prognosis and have led to better patient outcomes. Nowadays, biopsy specimens serve to ascertain diagnosis and determine tumor type. However, liquid biopsies present distinct advantages over conventional biopsy techniques. They offer a noninvasive, easily administered procedure, delivering insights into the tumor's status and facilitating real-time monitoring. Liquid biopsies encompass a variety of elements, such as circulating tumor cells, circulating tumor DNA, extracellular vesicles, microRNAs, circulating RNA, tumor platelets, and tumor endothelial cells. This review aims to provide an overview of the clinical applications of liquid biopsy as a technique in the management of pancreatic cancer.

Methods for the purification and detection of single nucleotide KRAS mutations on extrachromosomal circular DNA in human plasma

BACKGROUNDS

Despite recent advances, many cancers are still detected too late for curative treatment. There is, therefore, a need for the development of new diagnostic methods and biomarkers. One approach may arise from the detection of extrachromosomal circular DNA (eccDNA), which is part of cell-free DNA in human plasma.

AIMS

First, we assessed and compared two methods for the purification of eccDNA from plasma. Second, we tested for an easy diagnostic application of eccDNA liquid biopsy-based assays.

MATERIALS & METHODS

For the comparison we tested a solid-phase silica purification method and a phenol/chloroform method with salt precipitation. For the diagnostic application of eccDNA we developed and tested a qPCR primer-based SNP detection system, for the detection of two well-established cancer-causing KRAS mutations (G12V and G12R) on circular DNA. This investigation was supported by purifying, sequencing, and analysing clinical plasma samples for eccDNAs containing KRAS mutant alleles in 0.5 mL plasma from 16 pancreatic ductal adenocarcinoma patients and 19 healthy controls.

RESULTS

In our method comparison we observed, that following exonuclease treatment a lower eccDNA yield was found for the phenol/chloroform method (15.7%-26.7%) compared with the solid-phase purification approach (47.8%-65.9%). For the diagnostic application of eccDNA tests, the sensitivity of the tested qPCR assay only reached ~10-3 in a background of 105 wild type (wt) KRAS circular entities, which was not improved by general amplification or primer-based inhibition of wt KRAS amplification. Furthermore, we did not detect eccDNA containing KRAS in any of the clinical samples.

DISCUSSION

A potential explanation for our inability to detect any KRAS mutations in the clinical samples may be related to the general low abundance of eccDNA in plasma.

CONCLUSION

Taken together our results provide a benchmark for eccDNA purification methods while raising the question of what is required for the optimal fast and sensitive detection of SNP mutations on eccDNA with greater sensitivity than primer-based qPCR detection.

ALU repeat as potential molecular marker in the detection and prognosis of different cancer types: A systematic review

Cancer is a major health issue worldwide. cfDNA integrity has been reported as a potential diagnostic molecular marker for different types of cancer, identifying the importance of liquid biopsy. The aim of this review was to evaluate the prognostic and diagnostic performance of Arthrobacter luteus (ALU) repeat in tumor. Following a thorough review of the literature published from January, 2000 to September 2021, 36 studies were included. All of the study descriptions were analyzed. According to several studies, there were increased concentrations of ALU repetitive elements in cancer patients, while these concentrations were decreased in control, benign, different cancer stage, and other diseases. The total ALU (115 and 247) sequence levels are potential biomarkers for the purpose of investigations and cancer prognosis.

Role of Cell-Free DNA and Deoxyribonucleases in Tumor Progression

Many studies have reported an increase in the level of circulating cell-free DNA (cfDNA) in the blood of patients with cancer. cfDNA mainly comes from tumor cells and, therefore, carries features of its genomic profile. Moreover, tumor-derived cfDNA can act like oncoviruses, entering the cells of vulnerable organs, transforming them and forming metastatic nodes. Another source of cfDNA is immune cells, including neutrophils that generate neutrophil extracellular traps (NETs). Despite the potential eliminative effect of NETs on tumors, in some cases, their excessive generation provokes tumor growth as well as invasion. Considering both possible pathological contributions of cfDNA, as an agent of oncotransformation and the main component of NETs, the study of deoxyribonucleases (DNases) as anticancer and antimetastatic agents is important and promising. This review considers the pathological role of cfDNA in cancer development and the role of DNases as agents to prevent and/or prohibit tumor progression and the development of metastases.

Cell free DNA as an evolving liquid biopsy biomarker for initial diagnosis and therapeutic nursing in Cancer- An evolving aspect in Medical Biotechnology

Cell-free DNA (cfDNA) is present in numerous body fluids in addition to initiates generally from blood cells. It is undoubtedly the utmost promising tool among all components of liquid biopsy. Liquid biopsy is a specialized method investigating the nonsolid biological tissue by revealing of circulating cells, cell free DNA etc. that enter body fluids. Since, cancer cells disengage from compact tumors circulate in peripheral blood, evaluating blood of cancer patients holds the opportunities for capture and molecular level analysis of various tumor-derived constituents. Cell free DNA samples can deliver a significant perceptions into oncology, for instance tumor heterogeneity, instantaneous tumor development, response to therapy and treatment, comprising immunotherapy and mechanisms of cancer metastasis. Malignant growth at any phase can outhouse tumor cells in addition to fragments of neoplasticity causing DNA into circulatory system giving noble sign of mutation in the tumor at sampling time. Liquid biopsy distinguishes diverse blood based evolving biomarkers comprising circulating tumor cells (CTCs), circulating tumor DNA (ctDNA) or cfDNA, circulating RNA (cfRNA) and exosomes. Cell free DNA are little DNA fragments found circulating in plasma or serum, just as other fluids present in our body. Cell free DNA involves primarily double stranded nuclear DNA and mitochondrial DNA, present both on a surface level and in the lumen of vesicles. The probable origins of the tumor-inferred portion of cfDNA are apoptosis or tumor necrosis, lysis of CTCs or release of DNA from the tumor cells into circulation. The evolution of innovations, refinement and improvement in therapeutics for determination of cfDNA fragment size and its distribution provide significant information related with pathological conditions of the cell, thus emerging as promising indicator for clinical output in medical biotechnology.

Digital PCR-based plasma cell-free DNA mutation analysis for early-stage pancreatic tumor diagnosis and surveillance

BACKGROUND

Cell-free DNA (cfDNA) shed from tumors into the circulation offers a tool for cancer detection. Here, we evaluated the feasibility of cfDNA measurement and utility of digital PCR (dPCR)-based assays, which reduce subsampling error, for diagnosing pancreatic ductal adenocarcinoma (PDA) and surveillance of intraductal papillary mucinous neoplasm (IPMN).

METHODS

We collected plasma from seven institutions for cfDNA measurements. Hot-spot mutations in KRAS and GNAS in the cfDNA from patients with PDA (n = 96), undergoing surveillance for IPMN (n = 112), and normal controls (n = 76) were evaluated using pre-amplification dPCR.

RESULTS

Upon Qubit measurement and copy number assessment of hemoglobin-subunit (HBB) and mitochondrially encoded NADH:ubiquinone oxidoreductase core subunit 1 (MT-ND1) in plasma cfDNA, HBB offered the best resolution between patients with PDA relative to healthy subjects [area under the curve (AUC) 0.862], whereas MT-ND1 revealed significant differences between IPMN and controls (AUC 0.851). DPCR utilizing pre-amplification cfDNA afforded accurate tumor-derived mutant KRAS detection in plasma in resectable PDA (AUC 0.861-0.876) and improved post-resection recurrence prediction [hazard ratio (HR) 3.179, 95% confidence interval (CI) 1.025-9.859] over that for the marker CA19-9 (HR 1.464; 95% CI 0.674-3.181). Capturing KRAS and GNAS could also provide genetic evidence in patients with IPMN-associated PDA and undergoing pancreatic surveillance.

CONCLUSIONS

Plasma cfDNA quantification by distinct measurements is useful to predict tumor burden. Through appropriate methods, dPCR-mediated mutation detection in patients with localized PDA and IPMN likely to progress to invasive carcinoma is feasible and complements conventional biomarkers.

Cell-free nucleic acid patterns in disease prediction and monitoring-hype or hope?

Interest in the use of cell-free nucleic acids (CFNAs) as clinical non-invasive biomarker panels for prediction and prevention of multiple diseases has greatly increased over the last decade. Indeed, circulating CFNAs are attributable to many physiological and pathological processes such as imbalanced stress conditions, physical activities, extensive apoptosis of different origin, systemic hypoxic-ischemic events and tumour progression, amongst others. This article highlights the involvement of circulating CFNAs in local and systemic processes dealing with the question, whether specific patterns of CFNAs in blood, their detection, quantity and quality (such as their methylation status) might be instrumental to predict a disease development/progression and could be further utilised for accompanying diagnostics, targeted prevention, creation of individualised therapy algorithms, therapy monitoring and prognosis. Presented considerations conform with principles of 3P medicine and serve for improving individual outcomes and cost efficacy of medical services provided to the population.

Clinical value of tissue DNA integrity index in pancreatic cancer

BACKGROUND

DNA integrity index as a blood biomarker is associated with the prognosis of cancer patients.

AIMS

The primary goal of the study was to examine tissue DNA integrity index (DII) in a group of pancreatic cancer (PC) tumor tissues and control adjacent pancreatic tissues. We also aimed to test the relationship between the tumor tissue DII and the clinicopathological parameters and the overall survival.

METHODS

In the prospective study, DII was calculated using: the Alu 247/115 ratio, the LINE1 300/79 ratio and the average of the above values, based on the data obtained by real-time PCR. The tumors samples (n = 42) originated from the patients with pathologically confirmed pancreatic ductal adenocarcinoma and the control adjacent pancreatic tissue specimens (n = 32) were received from surgical margins.

RESULTS

Specimens from the tumors pathologically marked as R1 (microscopic residual tumor) had a significantly higher LINE1 300/79 ratio values than specimens from adjacent normal pancreatic tissue (P<0.05). ROC curve analysis revealed that LINE1 300/79 ratio is a good parameter to distinguish between R0 and R1 tumors (AUC = 0.703, P<0.05).

CONCLUSIONS

This is the first study exploring the tissue DNA integrity index (DII) in pancreatic cancer. LINE1 DII can be used as auxiliary parameter for objective evaluation of margin status.

Circulating Tumor Cells and Cell-Free DNA in Pancreatic Ductal Adenocarcinoma

Pancreatic cancer is detected late in the disease process and has an extremely poor prognosis. A blood-based biomarker that can enable early detection of disease, monitor response to treatment, and potentially allow for personalized treatment would be of great benefit. This review analyzes the literature regarding two potential biomarkers, circulating tumor cells (CTCs) and cell-free DNA (cfDNA), with regard to pancreatic ductal adenocarcinoma. The origin of CTCs and the methods of detection are discussed and a decade of research examining CTCs in pancreatic cancer is summarized, including both levels of CTCs and analyzing their molecular characteristics and how they may affect survival in both advanced and early disease and allow for treatment monitoring. The origin of cfDNA is discussed, and the literature over the past 15 years is summarized. This includes analyzing cfDNA for genetic mutations and methylation abnormalities, which have the potential to be used for the detection and prognosis of pancreatic ductal adenocarcinoma. However, the research certainly remains in the experimental stage, warranting future large trials in these areas.

Liquid Biopsy as Surrogate for Tissue for Molecular Profiling in Pancreatic Cancer: A Meta-Analysis Towards Precision Medicine

Liquid biopsy (LB) is a non-invasive approach representing a promising tool for new precision medicine strategies for cancer treatment. However, a comprehensive analysis of its reliability for pancreatic cancer (PC) is lacking. To this aim, we performed the first meta-analysis on this topic. We calculated the pooled sensitivity, specificity, positive (LR+) and negative (LR−) likelihood ratio, and diagnostic odds ratio (DOR). A summary receiver operating characteristic curve (SROC) and area under curve (AUC) were used to evaluate the overall accuracy. We finally assessed the concordance rate of all mutations detected by multi-genes panels. Fourteen eligible studies involving 369 patients were included. The overall pooled sensitivity and specificity were 0.70 and 0.86, respectively. The LR+ was 3.85, the LR- was 0.34 and DOR was 15.84. The SROC curve with an AUC of 0.88 indicated a relatively high accuracy of LB for molecular characterization of PC. The concordance rate of all mutations detected by multi-genes panels was 31.9%. LB can serve as surrogate for tissue in the molecular profiling of PC, because of its relatively high sensitivity, specificity and accuracy. It represents a unique opportunity to be further explored towards its introduction in clinical practice and for developing new precision medicine approaches against PC.

Opportunities of circulating tumor DNA in lung cancer

Current classification and treatment of lung cancer rely increasingly on molecular and genetic testing. Obtaining tumor tissue is not always feasible and multiple biopsies are undesirable. In response to the demand for non-invasive molecular and genetic testing in cancer care, several liquid biopsy technologies, including circulating DNA (ctDNA), have been developed. ctDNA analysis is now technically feasible to be carried out in large scales and integrated into clinical practice owing to the advances in technology. Despite the challenges in improving test accuracy and cost-effectiveness, there are huge potentials for ctDNA analysis in lung cancer management. This review focuses on the clinical utility of ctDNA analysis in lung cancer, including early detection, monitoring treatment response and detecting residual disease, identification of genetic determinants for targeted therapy, and predicting efficacy of immune checkpoint blockade.

Circulating Biomarkers for Response Prediction of Rectal Cancer to Neoadjuvant Chemoradiotherapy

Rectal cancer response to neoadjuvant Chemoradiotherapy (pCRT) is highly variable. In fact, it has been estimated that only about 21 % of patients show pathologic Complete Response (pCR) after therapy, while in most of the patients a partial or incomplete tumour regression is observed. Consequently, patients with a priori chemoradioresistant tumour should not receive the treatment, which is associated with substantial adverse effects and does not guarantee any clinical benefit. For Locally Advanced Rectal Cancer Patients (LARC), a standardized neoadjuvant treatment protocol is applied, the identification and the usefulness of prognostic or predictive biomarkers can improve the antitumoural treatment strategy, modifying the sequence, dose, and combination of radiotherapy, chemotherapy and surgical resection. For these reasons, a growing number of studies are actually focussed on the discovery and investigation of new predictive biomarkers of response to pCRT. In this review, we have selected the most recent literature (2012-2017) regarding the employment of blood-based biomarkers potentially predicting pCR in LARC patients and we have critically discussed them to highlight their real clinical benefit and the current limitations of the proposed methodological approaches.

Neuroendocrine neoplasms: current and potential diagnostic, predictive and prognostic markers

Some biomarkers for functioning and non-functioning neuroendocrine neoplasms (NENs) are currently available. Despite their application in clinical practice, results should be interpreted cautiously. Considering the variable sensitivity and specificity of these parameters, there is an unmet need for novel biomarkers to improve diagnosis and predict patient outcome. Nowadays, several new biomarkers are being evaluated and may become future tools for the management of NENs. These biomarkers include (1) peptides and growth factors; (2) DNA and RNA markers based on genomics analysis, for example, the so-called NET test, which has been developed for analyzing gene transcripts in circulating blood; (3) circulating tumor/endothelial/progenitor cells or cell-free tumor DNA, which represent minimally invasive methods that would provide additional information for monitoring treatment response and (4) improved imaging techniques with novel radiolabeled somatostatin analogs or peptides. Below we summarize some future directions in the development of novel diagnostic and predictive/prognostic biomarkers in NENs. This review is focused on circulating and selected tissue markers.

The Significance of Liquid Biopsy in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal types of cancer. The 5-year survival rate for PDAC remains low because it is always diagnosed at an advanced stage and it is resistant to therapy. A biomarker, which could detect asymptomatic premalignant or early malignant tumors and predict the response to treatment, will benefit patients with PDAC. However, traditional biopsy has its limitations. There is an urgent need for a tumor biomarker that could easily and repeatedly sample and monitor, in real time, the progress of tumor development. Liquid biopsy could be a tool to assess potential biomarkers. In this review, we focused on the latest discoveries and advancements of liquid biopsy technology in pancreatic cancer research and demonstrated how this technology is being used in clinical applications.

Prognostic value of the DNA integrity index in patients with malignant lung tumors

Introduction

Lung cancer survival remains poor in the western world due to late presentation in most cases, leading to difficulty of treatment in these advanced and metastatic patients. Therefore, the development of a robust biomarker for prognosis and to monitor treatment response and relapse would be of great benefit. The use of Alu repeats and DNA Integrity Index has been shown to hold both diagnostic and prognostic value, and as it is obtained from the plasma of patients, it can serve as a non-invasive tool for routine monitoring. This study evaluates the efficiency of this technique in malignant lung cancer patients.

Methods

Plasma samples were collected from 48 patients, consisting of 29 lung cancer patients and 19 non-cancer controls. Alu repeat ratio and confounders were measured.

Results

Observations showed a higher Alu repeat ratio amongst the cancer group compared to controls (p=0.035), mean Alu ratio 0.38 (range 0.01-0.93) and 0.22 (0.007-0.44) respectively, ROC curve analysis AUC 0.61 (p=0.22). Analysis by staging was more promising, whereby a higher DNA Integrity Index was seen in advanced cases compared to both early stage and controls, p<0.0001; AUC: 0.92 (P=0.0002) and p=0.0006, AUC – 0.88 (p=0.0007) respectively, however no significant difference was observed in the early stage compared to controls. Short term survival data also showed a DNA Integrity Index of >0.5 to be associated with poorer overall survival p=0.03.

Conclusion

The results of this study show a potential use of Alu repeats ratios for prognostic purposes in the advanced setting for lung cancer patients.

Exosomes in Pancreatic Cancer: from Early Detection to Treatment

BACKGROUND

Pancreatic cancer (PC) remains one of the most fatal forms of cancer worldwide with incidence nearly equal to mortality. This is often attributed to the fact that diagnosis is often not made until later disease stages when treatment proves difficult. Efforts have been made to reduce the mortality of PC through improvements in early screening techniques and treatments of late-stage disease. Exosomes, small extracellular vesicles involved in cellular communication, have shown promise in helping understand PC disease biology.

METHODS

In this review, we discuss current studies of the role of exosomes in PC physiology, and their potential use as diagnostic and treatment tools.

RESULTS

Exosomes have a role in diagnosing pancreatic cancer and in understanding tumor biology including migration, proliferation, chemoresistance, immunosuppression, cachexia and diabetes, and have a potential role in therapy for pancreatic cancer.

CONCLUSIONS

Exosomal analysis is beneficial in demonstrating mechanisms behind PC growth and metastasis, immunosuppression, drug resistance, and paraneoplastic conditions. Furthermore, the use of exosomes can be beneficial in detecting early-stage PC and exosomes have potential applications as therapeutic targets.

Circulating cell-free plasma tumour DNA shows a higher incidence of EGFR mutations in patients with extrathoracic disease progression

Background

Non-invasive monitoring of epidermal growth factor receptor (EGFR) mutations conferring sensitivity and resistance to tyrosine kinase inhibitors (TKIs) is vital for efficient therapy of lung adenocarcinoma (LADC). Although plasma circulating cell-free tumour DNA (ctDNA) is detectable at an early stage, the size of the tumour does not strongly correlate with concentration of whole cell-free DNA (cfDNA), including normal leucocyte DNA. We sought to examine the clinical features of patients with LADC whose cfDNA examination held clues for analysis of cancer genomics.

Methods

Forty-four plasma samples from 37 patients with LADC receiving EGFR-TKI therapy, including 20 who developed resistance, were prospectively subjected to droplet digital PCR-cfDNA analysis to detect EGFR mutations and analysed according to clinical features.

Results

cfDNA samples from 28 (64%) of the 44 samples were positive for TKI-sensitive mutations. Samples from 19 (95%) of the 20 EGFR-TKI-resistant patients were positive for TKI-sensitive mutations. In 24 patients without TKI resistance, 7 (54%) of 13 patients with regional lymph node metastases, 4 (67%) of 6 patients with advanced T stage (T3 or T4) and 8 (57%) of 14 patients with extrathoracic disease progression were also positive for TKI-sensitive mutations. cfDNA analysis from patients with acquired TKI-resistance disease or extrathoracic disease progression correlated with a high detection rate of TKIsensitive mutations (acquired resistance: risk ratio=2.53, 95% CI 1.50 to 4.29; extrathoracic disease progression: risk ratio=5.71, 95% CI 0.84 to 36.74).

Conclusions

cfDNA in patients with EGFR-TKI-resistance or extrathoracic disease progression may be useful for analysis of cancer genomics.

Trial registration number

UMIN 000017581.

The evidence base for circulating tumour DNA blood-based biomarkers for the early detection of cancer: a systematic mapping review

BACKGROUND

The presence of circulating cell-free DNA from tumours in blood (ctDNA) is of major importance to those interested in early cancer detection, as well as to those wishing to monitor tumour progression or diagnose the presence of activating mutations to guide treatment. In 2014, the UK Early Cancer Detection Consortium undertook a systematic mapping review of the literature to identify blood-based biomarkers with potential for the development of a non-invasive blood test for cancer screening, and which identified this as a major area of interest. This review builds on the mapping review to expand the ctDNA dataset to examine the best options for the detection of multiple cancer types.

METHODS

The original mapping review was based on comprehensive searches of the electronic databases Medline, Embase, CINAHL, the Cochrane library, and Biosis to obtain relevant literature on blood-based biomarkers for cancer detection in humans (PROSPERO no. CRD42014010827). The abstracts for each paper were reviewed to determine whether validation data were reported, and then examined in full. Publications concentrating on monitoring of disease burden or mutations were excluded.

RESULTS

The search identified 94 ctDNA studies meeting the criteria for review. All but 5 studies examined one cancer type, with breast, colorectal and lung cancers representing 60% of studies. The size and design of the studies varied widely. Controls were included in 77% of publications. The largest study included 640 patients, but the median study size was 65 cases and 35 controls, and the bulk of studies (71%) included less than 100 patients. Studies either estimated cfDNA levels non-specifically or tested for cancer-specific mutations or methylation changes (the majority using PCR-based methods).

CONCLUSION

We have systematically reviewed ctDNA blood biomarkers for the early detection of cancer. Pre-analytical, analytical, and post-analytical considerations were identified which need to be addressed before such biomarkers enter clinical practice. The value of small studies with no comparison between methods, or even the inclusion of controls is highly questionable, and larger validation studies will be required before such methods can be considered for early cancer detection.

Comparison of the tumor cell secretome and patient sera for an accurate serum-based diagnosis of pancreatic ductal adenocarcinoma

Pancreatic cancer is the currently most lethal malignancy. Toward an accurate diagnosis of the disease in body liquids, we studied the protein composition of the secretomes of 16 primary and established cell lines of pancreatic ductal adenocarcinoma (PDAC). Compared to the secretome of non-tumorous cells, 112 proteins exhibited significantly different abundances. Functionally, the proteins were associated with PDAC features, such as decreased apoptosis, better cell survival and immune cell regulation. The result was compared to profiles obtained from 164 serum samples from two independent cohorts - a training and a test set - of patients with PDAC or chronic pancreatitis and healthy donors. Eight of the 112 secretome proteins exhibited similar variations in their abundance in the serum profile specific for PDAC patients, which was composed of altogether 189 proteins. The 8 markers shared by secretome and serum yielded a 95.1% accuracy of distinguishing PDAC from healthy in a Receiver Operating Characteristic curve analysis, while any number of serum-only markers produced substantially less accurate results. Utility of the identified markers was confirmed by classical enzyme linked immunosorbent assays (ELISAs). The study highlights the value of cell secretome analysis as a means of defining reliable serum biomarkers.

Team work and cytopathology molecular diagnosis of solid pancreatic lesions

Pancreatic ductal adenocarcinoma (PDAC) is expected to become the second leading cause of cancer-associated death in the next decade or so. It is widely accepted that tumorigenesis is linked to specific alterations in key genes and pancreatic neoplasms are some of the best characterized at the genomic level. Recent whole-exome and whole-genome sequencing analyses confirmed that PDAC is frequently characterized by mutations in a set of four genes among others: KRAS, TP53, CDKN2A/p16, and SMAD4. Sequencing, for example, is the preferable technique available for detecting KRAS mutations, whereas in situ immunochemistry is the main approach for detecting TP53 gene alteration. Nevertheless, the diagnosis of PDAC is still a clinical challenge, involving adequate acquisition of endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) and specific pathological assessment from tissue architecture to specific biomolecular tests. The aim of the present review is to provide a complete overview of the current knowledge of the biology of pancreatic cancer as detected by the latest biomolecular techniques and, moreover, to propose a paradigm for strict teamwork collaboration in order to improve the correct use of diagnostic sources.

Quantification of metastatic load in a syngeneic murine model of metastasis

Bioluminescence imaging (BLI) is an established method for evaluating metastatic load in preclinical cancer models; however, BLI can produce observational error due to differences in substrate concentration and signal depth. In our syngeneic murine model of metastasis (VM-M3), we used a quantitative polymerase chain reaction (qPCR) method of DNA quantification to bypass these limitations. Liver, spleen, and brain from VM/Dk (VM) mice bearing VM-M3 tumor cells were first imaged ex vivo with BLI. qPCR quantification of tumor cell DNA was then performed on DNA extracted from these organs. Linear regression indicated that qPCR data predicted BLI data in solid tissue. Furthermore, the tumor cell detection limit was lower for qPCR analysis than for BLI analysis. In order to validate qPCR for use in detecting blood metastases, qPCR quantification was performed on whole blood collected from mice whose global organ metastatic load (summation of liver, spleen, kidneys, lungs, and brain) was quantified through BLI. Linear regression indicated that qPCR data in blood predicted BLI data in solid tissue. The results demonstrate that qPCR is an accurate and sensitive method of metastatic quantification in syngeneic murine models.

Circulating Tumor DNA as Biomarkers for Cancer Detection

Detection of circulating tumor DNAs (ctDNAs) in cancer patients is an important component of cancer precision medicine ctDNAs. Compared to the traditional physical and biochemical methods, blood-based ctDNA detection offers a non-invasive and easily accessible way for cancer diagnosis, prognostic determination, and guidance for treatment. While studies on this topic are currently underway, clinical translation of ctDNA detection in various types of cancers has been attracting much attention, due to the great potential of ctDNA as blood-based biomarkers for early diagnosis and treatment of cancers. ctDNAs are detected and tracked primarily based on tumor-related genetic and epigenetic alterations. In this article, we reviewed the available studies on ctDNA detection and described the representative methods. We also discussed the current understanding of ctDNAs in cancer patients and their availability as potential biomarkers for clinical purposes. Considering the progress made and challenges involved in accurate detection of specific cell-free nucleic acids, ctDNAs hold promise to serve as biomarkers for cancer patients, and further validation is needed prior to their broad clinical use.

Diagnostic and prognostic role of cell-free DNA testing for colorectal cancer patients

Circulating cell-free DNA (cfDNA) was found in increased amounts in cancer patients and tumor-associated molecular alteration can be detected in cancer patient's samples. For this reason, the cfDNA analysis is actually considered as a new concept of liquid biopsy. We evaluated the presence and integrity of plasma cfDNA by ALU-based qPCR and the methylation profile of OSMR and SFRP1 genes promoter in a large cohort of colorectal cancer (CRC) patients (n = 114) in comparison to healthy subjects (n = 56) and patients with adenomatous lesions (n = 22). Moreover, we studied the prognosis value focusing on histopathological staging and survival. The cfDNA concentration and the integrity index were increased in CRC patients. The ALU83 and ALU244 fragment dosage showed a moderate discriminant capacity between CRC patients and controls and CRC and adenoma patients. Especially, cfDNA was significantly higher in CRC patients at advanced histopathological stage. In addition, the increased cfDNA level was associated with poor prognosis. A comparison of methylation profile in matched tissue and plasma on 25 CRC patients was performed and only three mismatched cases were observed. A lower methylation quantification was observed in cfDNA than tissue DNA. The cfDNA methylation frequency was statistically different in controls, adenoma and CRC patients and this frequency increased with the histopathological stage of tumor. The adenoma and CRC patients methylated cfDNA showed a higher quantity of ALU83 and ALU244. An integrated approach, combining the detection of ALU fragments and cancer type-specific epigenetic alteration, can improve diagnostic efficiency and better define the prognostic value for CRC disease.

K-Ras Promotes Tumorigenicity through Suppression of Non-canonical Wnt Signaling

K-Ras and H-Ras share identical effectors and have similar properties; however, the high degree of tumor-type specificity associated with K-Ras and H-Ras mutations suggests that they have unique roles in oncogenesis. Here, we report that oncogenic K-Ras, but not H-Ras, suppresses non-canonical Wnt/Ca(2+) signaling, an effect that contributes strongly to its tumorigenic properties. K-Ras does this by binding to calmodulin and so reducing CaMKii activity and expression of Fzd8. Restoring Fzd8 in K-Ras mutant pancreatic cells suppresses malignancy, whereas depletion of Fzd8 in H-Ras(V12)-transformed cells enhances their tumor initiating capacity. Interrupting K-Ras-calmodulin binding using genetic means or by treatment with an orally active protein kinase C (PKC)-activator, prostratin, represses tumorigenesis in K-Ras mutant pancreatic cancer cells. These findings provide an alternative way to selectively target this "undruggable" protein.

Circulating DNA and Micro-RNA in Patients with Pancreatic Cancer

Collecting repeat samples of blood ("liquid biopsies") is a broadly used clinical approach for serial monitoring of disease or response to treatments. In patients with cancer the most distinct molecular feature are somatic mutations acquired by cancer cells present in the diseased tissue. Indeed, mutant DNA derived from dying or lysed cancer cells can be isolated from patient serum samples, subjected to DNA sequencing and to analysis of abundance as a measure of tumor burden. Also, changes in the DNA mutation patterns in serum samples collected over time can indicate altered pathways or clonal evolution of the disease and altered abundance of mutant DNA suggests an altered disease burden. In addition, during the course of treatment, changes in circulating DNA mutation patterns can indicate the emergence of resistant clones and prompt changes in treatment. In contrast to mutant DNA, microRNAs (miR) are transcribed, processed, packaged and released from cells in normal and in diseased tissues as part of the extracellular crosstalk between cells. Interestingly, released miR can function in cell-to-cell communication and as hormone-like signals that operate at a distance through their release into the circulation and subsequent uptake into cells in distant tissues. Circulating miR expression patterns can be established from serial serum samples and monitored for alterations over time. Circulating miR provide a readout of the organism's steady state and serial analyses will indicate changes in the response to therapy or an altered physiologic or disease state. Furthermore, changes in circulating miR patterns can indicate treatment efficacy or resistance as well as adverse effects associated with the respective intervention. Thus, the combined serial analysis of mutant DNA and miR in the circulation has the potential to provide a molecular footprint of pancreatic cancer and can be used to monitor treatment responses or resistance to treatment in real time with a minimally invasive procedure.

Genomic profiling guides the choice of molecular targeted therapy of pancreatic cancer

Pancreatic cancer has the worst five-year survival rate of all malignancies due to its aggressive progression and resistance to therapy. Current therapies are limited to gemcitabine-based chemotherapeutics, surgery, and radiation. The current trend toward "personalized genomic medicine" has the potential to improve the treatment options for pancreatic cancer. Gene identification and genetic alterations like single nucleotide polymorphisms and mutations will allow physicians to predict the efficacy and toxicity of drugs, which could help diagnose pancreatic cancer, guide neoadjuvant or adjuvant treatment, and evaluate patients' prognosis. This article reviews the multifaceted roles of genomics and pharmacogenomics in pancreatic cancer.