Low correspondence between K-ras mutations in pancreatic cancer tissue and detection of K-ras mutations in circulating DNA

Clinical significance of tumor suppressor genes methylation in circulating tumor DNA of patients with pancreatic cancer

BACKGROUND

Circulating tumor DNA (ctDNA) has emerged as a potential diagnostic and prognostic biomarker in various tumors. However, the role of tumor suppressor genes (TSGs) methylation in ctDNA of patients with pancreatic cancer (PC) remains largely unclear.

METHODS

Patients with PC (n = 43), pancreatic benign diseases (n = 39), and healthy controls (n = 20) were enrolled in the study. Quantitative analysis of methylation pattern of five candidate TSGs including NPTX2, RASSF1A, EYA2, p16, and ppENK in ctDNA was performed by next generation sequencing (NGS). The diagnostic performances of these 5-TSGs methylation were assessed by the operating characteristic (ROC) curve and clinicopathological features correlation analysis. Meanwhile, the changes in methylation levels of these 5-TSGs on the 7th postoperative day were evaluated in 23 PC patients who underwent radical resection.

RESULTS

The methylation levels of RASSF1A, EYA2, ppENK and p16 genes in patients with PC were significantly higher than those in healthy controls. EYA2, p16 and ppENK genes showed significantly hypermethylation in PC than those in pancreatic benign diseases. NPTX2, RASSF1A, EYA2, p16 and ppENK genes showed significantly hypermethylation in pancreatic benign diseases than those in healthy controls (P < 0.05). The methylation levels of these 5 candidate TSGs were not correlated with the tumor size, nerve invasion, lymph node metastasis and TNM stage of PC. The AUC of these biomarkers for diagnosis of PC ranged from 0.65 to 0.96. The AUC values of these methylated genes and CpG sites for differentiating malignant and benign pancreatic diseases were ranging from 0.68 to 0.92. Combined the hypermethylated genes improved the detective ability of PC than single gene. The methylation levels of NPTX2, EYA2 and ppENK genes were significantly decreased after radical resection of PC.

CONCLUSION

Quantitative analysis of methylation pattern of NPTX2, RASSF1A, EYA2, p16 and ppENK in ctDNA by NGS could be a valuable non-invasive tool for detection and monitoring of PC.

Diagnostic value of serum carbohydrate antigen 19-9 in pancreatic cancer: a systematic review and meta-analysis

Carbohydrate antigen 19-9 (CA19-9) is the most widely used serum biomarker for detecting pancreatic cancer (PC). Since early diagnosis is important for improving PC prognosis, a comprehensive understanding of the diagnostic performance of CA19-9 is critical. This study focused on comprehensive evaluation of the efficacy of CA19-9 in PC diagnosis. Literature research was based on the seven databases. Studies released from January 2002 to January 2022 focused on the efficacy of CA19-9 in the detection of PC were included. Summarized sensitivity, specificity, and sROC/accuracy of discrimination (AUC) were estimated. Potential publication bias was measured with Funnel plot and Egger's test. Meta-regression was performed to detect possible causes of heterogeneity. Subgroup analysis was used to assess the diagnostic efficacy of CA19-9 under different conditions. The study is registered on PROSPERO (CRD42021253861). Seventy-nine studies containing 20 991 participants who met the criteria were included. The pooled sensitivity, specificity, and AUC of CA19-9 in diagnose PC were 72% (95% CI, 71-73%), 86% (95% CI, 85-86%), and 0.8474 (95% CI, 0.8272-0.8676). Subgroup analysis suggested that the diagnostic efficiency of CA19-9 in studies with healthy controls was the highest, followed by intraductal papillary mucinous neoplasm, in pancreatitis and diabetes were consistent with the overall result. Our analysis showed that serum CA19-9 had high and stable diagnostic efficacy for PC (not affected by diabetes). Subgroup analysis showed that serum CA19-9 yielded highest effectiveness in the diagnosis of pancreatic precancerous lesions, which indicated an irreplaceable clinical value in the early detection and warning value for PC.

Impact of circulating tumor DNA in hepatocellular and pancreatic carcinomas

Hepatocellular carcinoma (HCC) and pancreatic cancer (PC) belong to the most lethal malignancies worldwide. Despite advances in surgical techniques and perioperative multidisciplinary management, the prognosis of both carcinoma entities remains poor mainly because of rapid tumor progression and early dissemination with diagnosis in advanced tumor stages with poor sensitivity to current therapy regimens. Both highly heterogeneous visceral carcinomas exhibit unique somatic alterations, but share common driver genes and mutations as well. Recently, circulating tumor DNA (ctDNA) could be identified as a liquid biopsy tool with huge potential as non-invasive biomarker in early diagnosis and prognosis. CtDNA released from necrotic or apoptotic cells of primary tumors, metastasis, and circulating tumor cells can reveal genetic and epigenetic alterations with tumor-specific and individual mutation and methylation profiles. In this article, we focus on clinical impact of ctDNA as potential biomarker in patients with HCC and PC.

Biochemical diagnostics of pancreatic cancer - Present and future

Pancreatic cancer is one of the deadliest cancers having an exceptionally high mortality rate. Despite a relatively low incidence (10th among cancers), it is the fourth leading cause of cancer-related deaths in most developed countries. Improving early diagnosis of pancreatic cancer and strengthening the standardised comprehensive treatment remain the main focus of pancreatic cancer research. Tumor markers are usually tumor-associated proteins of clinical relevance in these patients. Although tumor markers carbohydrate antigen (CA 19-9) and carcino-embryonic antigen (CEA) are commonly used, neither demonstrate high diagnostic accuracy. Recently, hematopoietic growth factors (HGFs) and various enzymes have been reported as potential biomarkers for pancreatic cancer. These include macrophage-colony stimulating factor (M-CSF) and granulocyte-colony stimulating factor (G-CSF), interleukin-3 (IL-3), macrophage inhibitory cytokine (MIC-1) and various enzymes (alcohol dehydrogenase, aldehyde dehydrogenase, lysosomal exoglycosidases). With the development of molecular technology, detecting K-ras mutation in serum via polymerase chain reaction (PCR) is becoming more common and efficient. Because K-ras mutation rates are high in many cancers, some regard it as a potential tumor marker. Others have shown the value of serum miRNAs in detection of pancreatic cancer. Unfortunately, there are currently no effective methods of sufficient diagnostic accuracy to detect early-stage surgically resectable pancreatic cancer. In this article we highlight these biomarkers and summarise recent developments in the diagnosis and treatment of pancreatic cancer.

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.

The emerging role of liquid biopsy in diagnosis, prognosis and treatment monitoring of pancreatic cancer

Circulating tumor DNA, circulating tumor cells and tumor-related exosomes may offer new opportunities to provide insights into the biological and clinical characteristics of a neoplastic disease. They represent alternative routes for diagnostic and prognostic purposes, and for predicting and longitudinally monitoring response to treatment and disease progression. Hence, circulating biomarkers represent promising noninvasive tools in the scenario of pancreatic cancer, where neither molecular nor clinical predictors of treatment benefit have been identified yet. This review aims to provide an overview of the current status of circulating biomarker research in pancreatic cancer, and discusses their potential clinical utility to facilitate clinical decision-making.

Progression of Chronic Pancreatitis to Pancreatic Cancer: Is There a Role of Gene Mutations as a Screening Tool?

OBJECTIVES

Early detection of pancreatic ductal adenocarcinoma still remains a challenge. Patients with chronic pancreatitis (CP) have a markedly increased risk of pancreatic cancer. Mutations in oncogenes and/or tumor suppressor genes play a role in development of pancreatic ductal adenocarcinoma. This study assessed mutations in KRAS and p53 gene in blood as a screening tool for malignant transformation in CP patients.

METHODS

This was a cohort, single-center study including 294 CP patients. DNA was isolated from plasma of CP patients, and KRAS mutations were identified using polymerase chain reaction-restriction fragment length polymorphism. Patients with positive KRAS mutation were screened for malignancy using positron emission tomography or endoscopic ultrasound. Mutations in p53 gene were analyzed by sequencing. Tissue samples from CP and pancreatic cancer patients were also tested for mutations in KRAS and p53 genes.

RESULTS

The plasma samples of 64 CP patients were positive for KRAS mutation, and 4 had mutation in p53 gene also. No patient positive for KRAS mutation and/or p53 mutation was found to have malignant transformation.

CONCLUSION

Detection of KRAS or p53 mutation in plasma is not an effective screening tool for pancreatic cancer because accumulation of multiple mutations is required for malignant transformation in the pancreas.

GANT-61 and GDC-0449 induce apoptosis of prostate cancer stem cells through a GLI-dependent mechanism

Aberrant reactivation of the Sonic Hedgehog (SHH) signaling pathway promotes prostate cancer (PC) growth and progression by regulating cancer-related genes through its downstream effectors GLI1 and GLI2. Therefore, targeting the SHH-GLI pathway provides an alternative approach to avoid cancer progression. The aim of this study was to delineate the underlying molecular mechanisms by which GDC-0449 (a SMO receptor inhibitor) and GANT-61 (a GLI transcription factor inhibitor) regulate cellular proliferation and self-renewal in human PC stem cells (ProCSCs). Inhibition of the SHH signaling pathway by GANT-61 induced apoptosis with more efficacy than by GDC-0449 in ProCSCs and PC cell lines. GLI1 and GLI2 expression, promoter-binding activity and GLI-responsive luciferase reporter activity were all decreased with either GDC-0449 or GANT-61 treatment. Expression of Fas, DR4, DR5, and cleavage of caspase-3 and PARP were increased, whereas levels of PDGFR-α and Bcl-2 were reduced. Double knockout of GLI1 and GLI2 using shRNA abolished the effects observed with either GDC-0449 or GANT-61 treatment. Collectively, our results showed that GANT-61 and GDC-0449 induced ProCSC apoptosis by directly or indirectly inhibiting the activities of the GLI family transcription factors, may enhance the efficacy of PC treatment.

Early changes in plasma DNA levels of mutant KRAS as a sensitive marker of response to chemotherapy in pancreatic cancer

Pancreatic cancer (PDAC) is still lacking of reliable markers to monitor tumor response. CA 19-9 is the only biomarker approved, despite it has several limitations in sensitivity and specificity. Since mutations of KRAS occur in more than 90% of tumors, its detection in circulating free tumor DNA (cftDNA) could represent a biomarker to monitor chemotherapy response. Twenty-seven advanced PDAC patients given first-line 5-fluorouracil, irinotecan and oxaliplatin or gemcitabine and nab-paclitaxel were enrolled. Three ml of plasma were collected: 1) before starting chemotherapy (baseline); 2) at day 15 of treatment; and 3) at each clinical follow-up. cftDNA was extracted and analysed for KRAS mutations (^mutKRAS) by digital droplet PCR. Nineteen patients displayed a ^mutKRAS in baseline plasma samples. There was a statistically significant difference in progression-free survival (PFS) and overall survival (OS) in patients with increase vs. stability/reduction of cftDNA in the sample collected at day 15 (median PFS 2.5 vs 7.5 months, p = 0.03; median OS 6.5 vs 11.5 months, p = 0.009). The results of this study demonstrate that cftDNA ^mutKRAS changes are associated with tumor response to chemotherapy and support the evidence that ^mutKRAS in plasma may be used as a new marker for monitoring treatment outcome and disease progression in PDAC.

Clinical value of ctDNA in upper-GI cancers: A systematic review and meta-analysis

BACKGROUND

The recent expanding technical possibilities to detect tumor derived mutations in blood, so-called circulating tumor DNA (ctDNA), has rapidly increased the interest in liquid biopsies. This review and meta-analysis explores the clinical value of ctDNA in malignancies of the upper gastro-intestinal tract.

METHODS

PubMed, Cochrane and Embase databases were searched to identify studies reporting the diagnostic, prognostic or predictive value of ctDNA in patients with esophageal, gastric and pancreatic cancer, until January 2017. The diagnostic accuracy and, using random-effect pair-wise meta-analyses, the prognostic value of ctDNA was assessed.

RESULTS

A total of 34 studies met the inclusion criteria. For esophageal and gastric cancer, amplification of oncogenes in blood, such as HER2 and MYC, can be relevant for diagnostic purposes, and to predict treatment response in certain patient subpopulations. Given the limited number of studies assessing the role of ctDNA in esophageal and gastric cancer, the meta-analysis estimated the diagnostic accuracy and predictive value of ctDNA in pancreatic cancer only (n=10). The pooled sensitivity and specificity of ctDNA as a diagnostic tool in pancreatic cancer were 28% and 95%, respectively. Patients with pancreatic cancer and detectable ctDNA demonstrated a worse overall survival compared to patients with undetectable ctDNA (HR 1.92, 95% confidence interval (CI) 1.15-3.22, p=0.01).

CONCLUSION

The presence of ctDNA is significantly associated with a poor prognosis in patients with pancreatic cancer. The use of ctDNA in clinical practice is promising, although standardization of sequencing techniques and further development of high-sensitive detection methods is needed.

Plasma Circulating Tumor DNA in Pancreatic Cancer Patients Is a Prognostic Marker

PURPOSE

Despite recent therapeutic advances, prognosis of patients with pancreatic adenocarcinoma remains poor. Analyses from tumor tissues present limitations; identification of informative marker from blood might be a promising alternative. The aim of this study was to assess the feasibility and the prognostic value of circulating tumor DNA (ctDNA) in pancreatic adenocarcinoma.

EXPERIMENTAL DESIGN

From 2011 to 2015, blood samples were prospectively collected from all consecutive patients with pancreatic adenocarcinoma treated in our center. Identification of ctDNA was done with next-generation sequencing targeted on referenced mutations in pancreatic adenocarcinoma and with picoliter droplet digital PCR.

RESULTS

A total of 135 patients with resectable (n = 31; 23%), locally advanced (n = 36; 27%), or metastatic (n = 68; 50%) pancreatic adenocarcinoma were included. In patients with advanced pancreatic adenocarcinoma (n = 104), 48% (n = 50) had ctDNA detectable with a median mutation allelic frequency (MAF) of 6.1%. The presence of ctDNA was strongly correlated with poor overall survival (OS; 6.5 vs. 19.0 months; P < 0.001) in univariate and multivariate analyses (HR = 1.96; P = 0.007). To evaluate the impact of ctDNA level, patients were grouped according to MAF tertiles: OS were 18.9, 7.8, and 4.9 months (P < 0.001). Among patients who had curative intent resection (n = 31), 6 had ctDNA detectable after surgery, with an MAF of 4.4%. The presence of ctDNA was associated with a shorter disease-free survival (4.6 vs.17.6 months; P = 0.03) and shorter OS (19.3 vs. 32.2 months; P = 0.027).

CONCLUSIONS

ctDNA is an independent prognostic marker in advanced pancreatic adenocarcinoma. Furthermore, it arises as an indicator of shorter disease-free survival in resected patients when detected after surgery. Clin Cancer Res; 23(1); 116-23. ©2016 AACR.

Circulating Tumor Cells and Circulating Tumor DNA Provide New Insights into Pancreatic Cancer

Pancreatic cancer has a rather dismal prognosis mainly due to high malignance of tumor biology. Up to now, the relevant researches on pancreatic cancer lag behind seriously partly due to the obstacles for tissue biopsy, which handicaps the understanding of molecular and genetic features of pancreatic cancer. In the last two decades, liquid biopsy, including circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA), is promising to provide new insights into the biological and clinical characteristics of malignant tumors. Both CTCs and ctDNA provide an opportunity for studying tumor heterogeneity, drug resistance, and metastatic mechanism for pancreatic cancer. Furthermore, they can also play important roles in detecting early-stage tumors, providing prognostic information, monitoring tumor progression and guiding treatment regimens. In this review, we will introduce the latest findings on biological features and clinical applications of both CTCs and ctDNA in pancreatic cancer. In a word, CTCs and ctDNA are promising to promote precision medicine in pancreatic cancer.

Clinical relevance of circulating KRAS mutated DNA in plasma from patients with advanced pancreatic cancer

We used KRAS mutations to investigate the clinical relevance of circulating tumor DNA (ctDNA) measurements in patients with advanced pancreatic cancer. Fifty-three blood samples were collected from 14 prospectively recruited patients prior to chemotherapy (gemcitabine or FOLFIRINOX) and subsequently every month during treatment. Samples were processed by density centrifugation and plasma DNA isolation. A Peptide-nucleic acid-clamp PCR was then used to detect KRAS mutations (present in >90% of pancreatic cancers) as a surrogate marker for ctDNA. Plasma samples from 29 healthy individuals were analyzed as a reference group. Results were compared to conventional monitoring measures and survival data. Median follow-up time was 3.7 months (range 0.6-12.9 months). Ten (71%) patients had a positive KRAS status in the plasma samples obtained prior to chemotherapy, indicating the presence of ctDNA. Among the patients who were ctDNA-positive before chemotherapy, nine (90%) experienced disease progression during follow-up, compared to one (25%) of four ctDNA-negative patients (P = 0.01). The pre-therapy ctDNA level was a statistically significant predictor of both progression-free and overall survival (P = 0.014 and 0.010, respectively). Of the 14 patients, ten had ≥2 follow-up samples; in several of these patients, the ctDNA level changed substantially during the course of chemotherapy. Changes in ctDNA levels corresponded both with radiological follow-up data and CA19-9 levels for several patients. This pilot study supports the hypothesis that ctDNA may be used as a marker for monitoring treatment efficacy and disease progression in pancreatic cancer patients. Recruitment of more patients is ongoing to corroborate these findings.

Snail transcript levels in diagnosis of pancreatic carcinoma with fine-needle aspirate

Expression of the transcription factor Snail that mediates epithelial-mesenchymal transition is correlated with poor prognosis in many tumour types. The aim of this study is to determine, as a proof of principle, whether Snail messenger RNA (mRNA) could be detected in fine-needle aspirate (FNA) biopsies of pancreatic ductal adenocarcinoma (PDAC) and could accurately differentiate malignant from benign pancreatic tissues. We also investigate the expression of Snail mRNA and its clinical significance in PDAC. FNA (22- or 25-gauge needle) samples were obtained from patients from June 1999 to June 2010. FNA samples that were either benign or chronic pancreatitis or confirmed as PDAC were included in this study. Snail mRNA was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The associations of Snail mRNA expression with various clinicopathological parameters was analysed in addition to the relation between its expression and patient survival. Levels of Snail mRNA were increased in tumour samples in comparison to benign and chronic pancreatitis. Transcript copy numbers for Snail were 0.7 ± 0.21 for tumour, 0.16 ± 0.09 for benign (P = 0.002) and 0.23 ± 0.12 for chronic pancreatitis (P = 0.024). Snail expression was found to be associated significantly with lymph node metastasis (P = 0.001), perineural invasion (P = 0.038) and elevated preoperative serum carcinoembryonic antigen (CEA) level (P = 0.043). Snail mRNA was increased in patients with poor outcome compared with those who remained alive and well. Snail mRNA levels can aid in the pathological evaluation of suspicious cases and may become a valuable asset in obtaining a definitive diagnosis of PDAC. The strong association between Snail expression and lymph node metastasis suggests that Snail mRNA can be used as an adjunct to lymph node positivity to predict survival in pancreatic cancer.

The receptor for advanced glycation end products (RAGE) enhances autophagy and neutrophil extracellular traps in pancreatic cancer

Neutrophil extracellular traps (NETs) are formed when neutrophils expel their DNA, histones and intracellular proteins into the extracellular space or circulation. NET formation is dependent on autophagy and is mediated by citrullination of histones to allow for unwinding and subsequent expulsion of DNA. NETs play an important role in the pathogenesis of several sterile inflammatory diseases, including malignancy, therefore we investigated the role of NETs in the setting of pancreatic ductal adenocarcinoma (PDA). Neutrophils isolated from two distinct animal models of PDA had an increased propensity to form NETs following stimulation with platelet activating factor (PAF). Serum DNA, a marker of circulating NET formation, was elevated in tumor bearing animals as well as in patients with PDA. Citrullinated histone H3 expression, a marker of NET formation, was observed in pancreatic tumors obtained from murine models and patients with PDA. Inhibition of autophagy with chloroquine or genetic ablation of RAGE resulted in decreased propensity for NET formation, decreased serum DNA, and decreased citrullinated histone H3 expression in the pancreatic tumor microenvironment. We conclude that NETs are upregulated in pancreatic cancer through RAGE dependent/autophagy pathways.

Circulating free DNA as biomarker and source for mutation detection in metastatic colorectal cancer

BACKGROUND

Circulating cell-free DNA (cfDNA) in plasma has shown potential as biomarker in various cancers and could become an importance source for tumour mutation detection. The objectives of our study were to establish a normal range of cfDNA in a cohort of healthy individuals and to compare this with four cohorts of metastatic colorectal cancer (mCRC) patients. We also investigated the prognostic value of cfDNA and analysed the tumour-specific KRAS mutations in the plasma.

METHODS

The study was a prospective biomarker evaluation in four consecutive Phase II trials, including 229 patients with chemotherapy refractory mCRC and 100 healthy individuals. Plasma was obtained from an EDTA blood-sample, and the total number of DNA alleles and KRAS mutated alleles were assessed using an in-house ARMS-qPCR as previously described.

RESULTS

Median cfDNA levels were higher in mCRC compared to controls (p < 0.0001). ROC analysis revealed an AUC of 0.9486 (p<0.00001). Data showed impaired OS with increasing levels of baseline cfDNA both when categorising patients by quartiles of cfDNA and into low or high cfDNA groups based on the upper normal range of the control group (Median OS 10.2 (8.3-11.7) and 5.2 (4.6-5.9) months, respectively, HR 1.78, p = 0.0006). Multivariate analysis confirmed an independent prognostic value of cfDNA (HR 1.5 (95% CI 1.3-1.7) for each increase in the cfDNA quartile). The overall concordance of KRAS mutations in plasma and tissue was high (85%).

CONCLUSIONS

These data confirm the prognostic value of cfDNA measurement in plasma and utility for mutation detection with the method presented.

Novel blood-based microRNA biomarkers for diagnosis of pancreatic cancer: a meta-analysis

BACKGROUND

Recently, several studies have shown that blood-based microRNAs in patients with pancreatic cancer (PC) could be aberrantly expressed. The purpose of this meta-analysis was to evaluate blood-based microRNAs as novel biomarkers for diagnosis of PC.

METHODS

Eligible studies which had evaluated the diagnostic performance of blood-based microRNAs and had been published from February 2004 to February 2014 were retrieved. The quality of the studies was evaluated with the QUADAS-2 tool. The performance characteristics were pooled using random-effects models. Statistical analysis was performed with STATA and Meta-Disc1.4 software.

RESULTS

The global meta-analysis included 12 studies from 8 articles, which contained 1,060 blood-based samples of PC patients and 935 blood-based samples of non-PC patients. Summary results suggested pooled sensitivity of 0.87 (95% confidence interval [95% CI], 0.85-0.89), specificity 0.92 (95% CI, 0.90-0.94), positive likelihood ratio 11.18 (95% CI, 5.57-22.46), negative likelihood ratio 0.16 (95% CI, 0.11-0.23), diagnostic odds ratio 88.98 (95% CI, 39.85-198.69) and the area under the summary receiver operating characteristic (SROC) curve 0.96.

CONCLUSIONS

This meta-analysis demonstrated blood-based microRNA expression profiles with the potential to discriminate PC patients from non-PC patients, which have moderate diagnostic accuracy. However, further validation studies are needed for their clinical significance in the diagnosis of PC to be established.

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

BACKGROUND

Currently, no reliable blood-based assay for early detection of pancreatic ductal adenocarcinoma (PDAC) is available. Cell-free DNA (cfDNA) quantitation in patients' plasma has been recently applied in monitoring several cancer types. This study evaluates the diagnostic potential of cfDNA in PDAC patients.

METHODS

Plasma cfDNA levels and integrity ratio were assayed using quantitative real-time PCR of Alu-repeat amplicons in patients with pancreatic ductal adenocarcinoma (n=50), pancreatic neuroendocrine tumor (n=23), and chronic pancreatitis (n=20), as well as in healthy volunteers without evidence of pancreatic disease (n=23).

RESULTS

The total load of cfDNA, obtained by Alu83 quantitation, was the highest in PDAC patients than in any of the other patient groups (Welch t test; p<0.001) and was an average predictor of PDAC disease (AUC=0.664; CI, 0.56-0.77). A nonlinear association between Alu83 levels and subjects' age was detected (Spearman's rho=0.35; p<0.001) in the overall population, as well as within the PDAC patients' group (Spearman's rho=0.47; p<0.001). Necrosis-derived cfDNA fragments, quantitated with the Alu244 amplicon, were barely detectable in any of the samples and, in that respect, comparable between the different subject groups. CfDNA integrity estimation (Alu244/Alu83 ratio) was significantly affected by the limited detectability of plasma Alu244 levels.

CONCLUSION

The lack of detectable levels of necrosis-derived cfDNA in pancreatic pathologies considerably affects the clinical use of such biomarker in PDAC patients. Different methods of analysis should be applied in the evaluation of the cfDNA diagnostic value in pancreas pathology.

Pharmacodynamic separation of gemcitabine and erlotinib in locally advanced or metastatic pancreatic cancer: therapeutic and biomarker results

PURPOSE

Erlotinib marginally improves survival when administered continuously with gemcitabine to patients with advanced pancreatic cancer; however, preclinical data suggest that there is antagonism between chemotherapy and epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors when these are delivered concurrently. We tested a pharmacodynamic separation approach for erlotinib plus gemcitabine and interrogated EGFR signaling intermediates as potential surrogates for the efficacy of this strategy.

METHODS

Patients with measurable, previously untreated locally advanced unresectable or metastatic pancreatic cancer were treated with gemcitabine 1000 mg/m(2) as an intravenous infusion over 30-min on days 1, 8, 15 and erlotinib 150 mg/day on days 2-5, 9-12, 16-26 of each 28-day cycle. The primary endpoint was progression-free survival (PFS); secondary endpoints included RECIST objective response rate (ORR) and safety. The study was terminated after thirty patients due to funding considerations.

RESULTS

The median PFS was 2.07 months (95% CI; 1.87-5.50 months) and the ORR was 11%. No unexpected safety signals were seen: the most common grade 3 or higher adverse events were neutropenia (23%), lymphopenia (23%), and fatigue (13%). Patients with mutant plasma Kirsten rat sarcoma virus (KRAS) had significantly lower median PFS (1.8 vs. 4.6 months, p = 0.014) and overall survival (3.0 vs. 10.5 months, p = 0.003) than those without detected plasma KRAS mutations.

CONCLUSIONS

Although pharmacodynamically separated erlotinib and gemcitabine were feasible and tolerable in patients with advanced pancreatic cancer, no signal for increased efficacy was seen in this molecularly unselected cohort. Detection of a KRAS mutation in circulating cell-free DNA was a strong predictor of survival.

Quantitative assessment of the diagnostic role of MUC1 in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma has the worst prognosis of any gastrointestinal cancer, with the mortality approaching the incidence. Early detection is crucial for improving patient prognosis. We therefore performed a meta-analysis to assess the diagnostic performance of MUC1 for pancreatic ductal adenocarcinoma (PDAC). A comprehensive search was performed to retrieve relevant studies on detecting immunohistochemical expression of MUC1 in the diagnosis of PDAC. Data on accuracy of included studies were extracted for further heterogeneity exploring, statistical pooling, and SROC (summary receiver operating characteristics) analyzing using the Meta-DiSc 1.4 and STATA 12.0 software. Seventeen studies were se1ected with 1,363 patients involved. The heterogeneity (except for threshold effect) was found in these studies. The pooled sensitivity and specificity were 0.83 (95 % confidence interval (CI), 0.81-0.86) and 0.63 (95 % CI, 0.59-0.66), respectively. The pooled positive likelihood ratio (PLR) and negative likelihood ratio (NLR) were 3.02 (95 % CI, 1.95-4.70) and 0.21 (95 % CI, 0.13-0.32), respectively. The pooled diagnostic odds ratio (DOR) was 20.44 (95 % CI, 9.53-43.85). The area under of SROC curve was 0.8879 and the Q index was 0.8185. This meta-analysis indicates that MUC1 assay plays an important role in the diagnosis of PDAC.

Diagnostic accuracy of K-ras mutation for pancreatic carcinoma: a meta-analysis

BACKGROUND

The conventional tests for the diagnosis of early stage pancreatic carcinoma are not acceptable. This meta-analysis is to evaluate the accuracy of K-ras mutation for the diagnosis of pancreatic carcinoma.

DATA SOURCES

A systemic search of all relevant literature was performed in Web of Science, EMBASE, Cochrane Database, and MEDLINE (PubMed as the search engine) prior to June 1, 2011. Thirty-four studies fulfilled the inclusion criteria and data were pooled for analysis.

RESULTS

The pooled estimates for K-ras mutation in diagnosis of pancreatic carcinoma were as follows: sensitivity 0.68 (95% CI: 0.66-0.71), specificity 0.87 (95% CI: 0.85-0.88), positive likelihood ratio 4.54 (95% CI: 3.47-5.94), negative likelihood ratio 0.37 (95% CI: 0.30-0.44) and diagnostic odds ratio 14.90 (95% CI: 10.02-22.15). Summary receiver operating characteristic analysis demonstrated that the maximum joint sensitivity and specificity was 0.79, and the overall area under the curve was 0.86.

CONCLUSIONS

Diagnostic accuracy of K-ras mutation was not superior to that of conventional tests. Therefore, K-ras mutation analysis alone is not recommended for the diagnosis of pancreatic carcinoma.

GANT-61 inhibits pancreatic cancer stem cell growth in vitro and in NOD/SCID/IL2R gamma null mice xenograft

Multiple lines of evidence suggest that the Sonic Hedgehog (Shh) signaling pathway is aberrantly reactivated in pancreatic cancer stem cells (CSCs). The objectives of this study were to examine the molecular mechanisms by which GANT-61 (Gli transcription factor inhibitor) regulates stem cell characteristics and tumor growth. Effects of GANT-61 on CSC's viability, spheroid formation, apoptosis, DNA-binding and transcriptional activities, and epithelial-mesenchymal transition (EMT) were measured. Humanized NOD/SCID/IL2R gamma(null) mice were used to examine the effects of GANT-61 on CSC's tumor growth. GANT-61 inhibited cell viability, spheroid formation, and Gli-DNA binding and transcriptional activities, and induced apoptosis by activation of caspase-3 and cleavage of Poly-ADP ribose Polymerase (PARP). GANT-61 increased the expression of TRAIL-R1/DR4, TRAIL-R2/DR5 and Fas, and decreased expression of PDGFRα and Bcl-2. GANT-61 also suppressed EMT by up-regulating E-cadherin and inhibiting N-cadherin and transcription factors Snail, Slug and Zeb1. In addition, GANT-61 inhibited pluripotency maintaining factors Nanog, Oct4, Sox-2 and cMyc. Suppression of both Gli1 plus Gli2 by shRNA mimicked the changes in cell viability, spheroid formation, apoptosis and gene expression observed in GANT-61-treated pancreatic CSCs. Furthermore, GANT-61 inhibited CSC tumor growth which was associated with up-regulation of DR4 and DR5 expression, and suppression of Gli1, Gli2, Bcl-2, CCND2 and Zeb1 expression in tumor tissues derived from NOD/SCID IL2Rγ null mice. Our data highlight the importance of Shh pathway for self-renewal and metastasis of pancreatic CSCs, and also suggest Gli as a therapeutic target for pancreatic cancer in eliminating CSCs.

Diagnostic value of microRNA for pancreatic cancer: a meta-analysis

INTRODUCTION

MicroRNAs have been reported to be aberrantly expressed in patients with pancreatic cancer. The aim of the present meta-analysis is to establish the overall diagnostic accuracy of the measurement of microRNA for diagnosing pancreatic cancer.

MATERIAL AND METHODS

After a systematic review of English language studies from Medline, Embase, and Cochrane Library, the sensitivity, specificity, and other measures of accuracy of microRNA in the diagnosis of pancreatic cancer were pooled using random-effects models. The methodological quality of each study was assessed by QUADAS (quality assessment for studies of diagnostic accuracy). Statistical analysis was performed by employing Meta-Disc 1.4 software and STATA. Summary receiver operating characteristic curves were used to summarize overall test performance. Deeks' test was used to test the potential publication bias.

RESULTS

Nine studies from seven publications met our inclusion criteria. The summary estimates for microRNAs in the diagnosis of pancreatic cancer in these studies were pooled sensitivity 0.89 (95% CI: 0.86-0.91), specificity 0.93 (95% CI: 0.90-0.95), positive likelihood ratio 11.62 (95% CI: 5.75-23.50), negative likelihood ratio 0.14 (95% CI: 0.08-0.24), diagnostic odds ratio 115.13 (95% CI: 33.73-351.28), and the area under the curve was 0.97.

CONCLUSIONS

MicroRNA assay plays an important role in the diagnosis of pancreatic cancer. The results of microRNA assays should be interpreted in parallel with clinical findings and the results of conventional tests.

Mechanism of EGER-related cancer drug resistance

Drug resistance in cancer arises from a complex range of biochemical and molecular events, which ultimately result in tumor cell survival. Identifying key genes and signal pathways involved in the molecular mechanisms of drug resistance is essential for establishment of new drug targets for preventing further resistance development and spreading. Epidermal growth factor receptor (EGFR) was the first growth factor receptor proposed as a target for cancer therapy. Significant progress in studying EGFR gene expression and mutation has been made in understanding the molecular events involved in EGFR-targeted agents. Recently, some individual chromosomal features such as EGFR copy number variation were demonstrated as new aspects related to drug sensitivity. Identifying these functional regulators of drug resistance will benefit therapeutic decision-making. In this study, we describe an extensive investigation of the published literature on mutation, amplification, and expression of EGFR and its downstream signaling that directly contribute to EGFR inhibitor resistance, including the gene status of KRAS, BRAF, PIK3CA, PTEN, MEK, and AKT on response to therapy. Analysis of these gene signatures identified reveals general modes of action of multicomponent therapies and the mechanisms of specific drug combinations, highlights the potential value of molecular interaction profiles in the discovery of novel therapies, and provides more information for personalized cancer medicine.

Combination of plasma microRNAs with serum CA19-9 for early detection of pancreatic cancer

This study was performed to identify plasma microRNAs (miRNAs) as diagnostic biomarkers for pancreatic cancer (PCa) and to assess their supplementary role with serum CA19-9 in early identification of tumors. Plasma RNAs were extracted from 140 PCa patients, 111 chronic pancreatitis (CP) patients and 68 normal controls, and the relative abundances of seven miRNAs (miR-16, 21, 155, 181a, 181b, 196a and 210) were measured using real-time PCR. Their diagnostic utility for PCa and correlation with clinical characteristics were analyzed. All seven miRNAs were significantly aberrantly upregulated in the PCa group compared with both the CP and normal groups, between which only four miRNAs (miR-155, 181a, 181b and 196a) were significantly different. Logistic modeling proved that only miR-16 and miR-196a possessed an independent role in discriminating PCa from normal and CP. Furthermore, after including serum CA19-9 in the logistic model, the combination of miR-16, miR-196a and CA19-9 was more effective for discriminating PCa from non-PCa (normal+CP) (AUC-ROC, 0.979; sensitivity, 92.0%; specificity, 95.6%), and for discriminating PCa from CP (AUC-ROC, 0.956; sensitivity, 88.4%; specificity, 96.3%) compared with the miRNA panel (miR-16+miR-196a) or CA19-9 alone. Most significantly, the combination was effective at identification of tumors in Stage 1 (85.2%). In conclusion, plasma miRNAs were effective for distinguishing PCa from non-PCa (normal+CP). The combination of miR-16, miR-196a and CA19-9 was more effective for PCa diagnosis, especially in early tumor screening.

Hedgehog signaling antagonist GDC-0449 (Vismodegib) inhibits pancreatic cancer stem cell characteristics: molecular mechanisms

Background

Recent evidence from in vitro and in vivo studies has demonstrated that aberrant reactivation of the Sonic Hedgehog (SHH) signaling pathway regulates genes that promote cellular proliferation in various human cancer stem cells (CSCs). Therefore, the chemotherapeutic agents that inhibit activation of Gli transcription factors have emerged as promising novel therapeutic drugs for pancreatic cancer. GDC-0449 (Vismodegib), orally administrable molecule belonging to the 2-arylpyridine class, inhibits SHH signaling pathway by blocking the activities of Smoothened. The objectives of this study were to examine the molecular mechanisms by which GDC-0449 regulates human pancreatic CSC characteristics in vitro.

Methodology/Principal Findings

GDC-0499 inhibited cell viability and induced apoptosis in three pancreatic cancer cell lines and pancreatic CSCs. This inhibitor also suppressed cell viability, Gli-DNA binding and transcriptional activities, and induced apoptosis through caspase-3 activation and PARP cleavage in pancreatic CSCs. GDC-0449-induced apoptosis in CSCs showed increased Fas expression and decreased expression of PDGFRα. Furthermore, Bcl-2 was down-regulated whereas TRAIL-R1/DR4 and TRAIL-R2/DR5 expression was increased following the treatment of CSCs with GDC-0449. Suppression of both Gli1 plus Gli2 by shRNA mimicked the changes in cell viability, spheroid formation, apoptosis and gene expression observed in GDC-0449-treated pancreatic CSCs. Thus, activated Gli genes repress DRs and Fas expressions, up-regulate the expressions of Bcl-2 and PDGFRα and facilitate cell survival.

Conclusions/Significance

These data suggest that GDC-0499 can be used for the management of pancreatic cancer by targeting pancreatic CSCs.

Emerging molecular biomarkers--blood-based strategies to detect and monitor cancer

There is an urgent need for blood-based, noninvasive molecular tests to assist in the detection and diagnosis of cancers in a cost-effective manner at an early stage, when curative interventions are still possible. Additionally, blood-based diagnostics can classify tumors into distinct molecular subtypes and monitor disease relapse and response to treatment. Increasingly, biomarker strategies are becoming critical to identify a specific patient subpopulation that is likely to respond to a new therapeutic agent. The improved understanding of the underlying molecular features of common cancers and the availability of a multitude of recently developed technologies to interrogate the genome, transcriptome, proteome and metabolome of tumors and biological fluids have made it possible to develop clinically applicable and cost-effective tests for many common cancers. Overall, the paradigm shift towards personalized and individualized medicine relies heavily on the increased use of diagnostic biomarkers and classifiers to improve diagnosis, management and treatment. International collaborations, involving both the private and public sector will be required to facilitate the development of clinical applications of biomarkers, using rigorous standardized assays. Here, we review the recent technological and scientific advances in this field.

Clinical validity of detecting K-ras mutations for the diagnosis of exocrine pancreatic cancer: a prospective study in a clinically-relevant spectrum of patients

The diagnostic utility of detecting K-ras mutations for the diagnosis of exocrine pancreatic cancer (EPC) has not been properly studied, and few reports have analysed a clinically relevant spectrum of patients. The objective was to evaluate the clinical validity of detecting K-ras mutations in the diagnosis of EPC in a large sample of clinically relevant patients. We prospectively identified 374 patients in whom one of the following diagnoses was suspected at hospital admission: EPC, chronic pancreatitis, pancreatic cysts, and cancer of the extrahepatic biliary system. Mutations in the K-ras oncogene were analysed by PCR and artificial RFLP in 212 patients. The sensitivity and specificity of the K-ras mutational status for the diagnosis of EPC were 77.7% (95% CI: 69.2-84.8) and 78.0% (68.1-86.0), respectively. The diagnostic accuracy was hardly modified by sex and age. In patients with either mutated K-ras or CEA > 5 ng/ml, the sensitivity and specificity were 81.0% (72.9-87.6) and 62.6% (72.9-87.6), respectively. In patients with mutated K-ras and CEA > 5 ng/ml the sensitivity was markedly reduced. In comparisons with a variety of non-EPC patient groups sensitivity and specificity were both always greater than 75%. In this clinically relevant sample of patients the sensitivity and specificity of K-ras mutations were not sufficiently high for independent diagnostic use. However, it seems premature to rule out the utility of K-ras analysis in conjunction with other genetic and 'omics' technologies.

Possible role of autophagy in the treatment of pancreatic cancer with histone deacetylase inhibitors

Pancreatic cancer is a lethal disease and notoriously difficult to treat. Only a small proportion is curative by surgical resection, whilst standard chemotherapy for patients with advanced disease has only a modest effect with substantial toxicity. Clearly there is a need for the continual development of novel therapeutic agents to improve the current situation. Currently, there is a bulk of data indicating the important function of autophagy in cancer. While genetic evidence indicates that autophagy functions as a tumor suppressor, it is also apparent that autophagy can promote the survival of established tumors under stress conditions and in response to chemotherapy. This review provides a spectrum of potential pharmacological agents and autophagic approaches to enhance cell killing in pancreatic cancer.

Cell-free DNA in the blood as a solid tumor biomarker--a critical appraisal of the literature

Circulating cell-free DNA (cfDNA) has been suggested as a cancer biomarker. Several studies assessed the usefulness of quantitative and qualitative tumor-specific alterations of cfDNA, such as DNA strand integrity, frequency of mutations, abnormalities of microsatellites, and methylation of genes, as diagnostic, prognostic, and monitoring markers in cancer patients. Most of the papers that could be evaluated in this review resulted in a positive conclusion. However, methodical diversity without the traceability of data and differently designed and often underpowered studies resulted in divergent results between studies. In addition, the limited diagnostic sensitivity and specificity of cfDNA alterations temper the effusive hope of novel tumor markers, raising similar issues as those for other tumor markers. To validate the actual clinical validity of various cfDNA alterations as potential cancer biomarkers in practice for individual tumor types, the main problems of the observed uncertainties must be considered in future studies. These include methodical harmonization concerning sample collection, processing, and analysis with the traceability of measurement results as well as the realization of well-designed prospective studies based on power analysis and sample size calculations.

K-RAS mutation in the screening, prognosis and treatment of cancer

The potential use of K-RAS mutation as a cancer screening biomarker has been investigated for many years. Numerous associations between K-RAS mutation and various cancers have been established, but these associations have not been translated into effective, cost-efficient cancer screening strategies. This lack of progress may be due to the existence of K-RAS mutation in nontumor tissues and/or using detection, rather than quantitation, of K-RAS mutation as the endpoint for cancer risk categorization. K-RAS mutation appears to be a useful prognostic biomarker for colon cancer. Recent progress toward sensitive and quantitative mutation characterization and the successful use of K-RAS mutation in a personalized medicine approach to targeted biological therapy selection are likely to re-direct and expand the use of K-RAS mutation as a cancer biomarker in the near future.

Methylation profile of circulating plasma DNA in patients with pancreatic cancer

BACKGROUND AND OBJECTIVES

Detection of pancreatic cancer by blood-based test may improve outcomes. We sought to establish the feasibility of a blood-based detection of pancreatic cancer through multiplexed array-mediated analysis of DNA methylation.

METHODS

Methylation was assessed in each plasma sample using a panel of 56 frequently methylated genes. Methylation profiles in patients with ductal cell adenocarcinoma of the pancreas (n = 30) and healthy gender and age-matched controls (n = 30) were compared. Methylation was determined as described previously; a composite biomarker was developed for classification of cancer and normal samples. Sensitivity and specificity of the biomarker were estimated using 25 rounds of fivefold cross-validation.

RESULTS

Five promoters were consistently selected for the classifier during cross-validation and comprised the final composite biomarker Five-fold cross-validation results indicate 76% sensitivity and 59% specificity of the biomarker, which included promoters of CCND2, SOCS1, THBS1, PLAU, and VHL.

CONCLUSION

Differential methylation profiling of plasma DNA can detect ductal adenocarcinoma of the pancreas with significant accuracy and should be explored further. While additional improvement of biomarkers is necessary, the blood-based biomarker may be already useful as a first-line detection tool.

Analysis of K-ras gene codon 12 mutation in pancreatic tissue of patients with pancreatic cancer

The aim of this study was to analyze K-ras codon 12 mutation in the pancreatic tissue of Serbian patients with pancreatic cancer and assess whether the given mutation can be used as a molecular marker for this disease. The study was performed on pancreatic tissue samples obtained from 40 patients with clinical diagnosis of pancreatic cancer. The presence of K-ras codon 12 mutation was analyzed by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Our study showed that K-ras mutation is present with a high frequency (66%) in the pancreatic tissue of patients with pancretic cancer.

Analysis of microRNAs in pancreatic fine-needle aspirates can classify benign and malignant tissues

BACKGROUND

MicroRNAs (miRNAs) are RNA molecules that are involved in the regulation of many cellular processes, including those related to human cancers. The aim of this study was to determine, as a proof of principle, whether specific candidate miRNAs could be detected in fine-needle aspirate (FNA) biopsies of pancreatic ductal adenocarcinoma (PDAC) and could accurately differentiate malignant from benign pancreatic tissues.

METHODS

We used TaqMan(R) assays to quantify miRNA levels in FNA samples collected in RNARetain (n = 16) and compared the results with a training set consisting of frozen macrodissected pancreatic samples (n = 20).

RESULTS

Quantitative reverse-transcription PCR analysis confirmed that miRNA levels are affected in PDAC FNAs and correlate well with the changes observed in the training set of frozen pancreatic samples. Analysis of the amounts produced for a few specific miRNAs enabled identification of PDAC samples. The combination of miR-196a and miR-217 biomarkers further improved the ability to distinguish between healthy tissue, PDAC, and chronic pancreatitis in the training set (P = 8.2 x 10(-10)), as well as segregate PDAC FNA samples from other FNA samples (P = 1.1 x 10(-5)). Furthermore, we showed that miR-196a production is likely specific to PDAC cells and that its incidence paralleled the progression of PDAC.

CONCLUSIONS

To the best of our knowledge, this study is the first to evaluate the diagnostic potential of miRNAs in a clinical setting and has shown that miRNA analysis of pancreatic FNA biopsy samples can aid in the pathologic evaluation of suspicious cases and may provide a new strategy for improving the diagnosis of pancreatic diseases.

Progress on molecular markers of pancreatic cancer

PURPOSE OF REVIEW

To describe advances in the development of biomarkers for pancreatic cancer over the past year.

RECENT FINDINGS

Several new approaches were taken in the search for biomarkers for pancreatic cancer. Studies of CA19-9 revealed new prognostic abilities of the already well known biomarker. New blood biomarkers were investigated and CEACAM1 and MIC-1 were found to be superior to CA19-9 at distinguishing cancer from normal but, unfortunately, not from chronic pancreatitis. MUC1 was reported to be superior to CA19-9 based on the use of a novel immunoassay. The superiority of the concept of a panel of biomarkers as opposed to single biomarkers was supported by several studies, but no such panel was identified. RNA levels in blood and DNA methylation in pancreatic juice yielded some promising findings. Advancements were also made in the area of tissue biomarkers, which can improve the diagnostic accuracy of fine-needle aspirations and provide prognostic information. A new source of potential biomarkers, microRNAs, also made its debut in the past year.

SUMMARY

The tools to identify pancreatic-cancer biomarkers and sources of samples needed in this search are expanding. The field has not yet achieved its aims, but several encouraging breakthroughs have been made.

Research progress in screening biomarkers of pancreatic cancer by proteomic techniques

Pancreatic cancer is one kind of devastating diseases. Those patients without nonspecific symptoms at early stage had mostly lost the opporunity of surgical therapy when pancreatic cancer was detected at advanced stage. Rapid growth of proteomic technologies provides possibilities to study etiopathogenesis, and screen early diagnostic and prognosis biomarkers of pancreatic cancer. In this paper, the application of proteomic techniques in cell lines, tissues, serum and pancreatic juice from patients with pancreatic cancer is reviewed briefly.

K-ras mutation and p16 and preproenkephalin promoter hypermethylation in plasma DNA of pancreatic cancer patients: in relation to cigarette smoking

OBJECTIVES

To examine the profiles of K-ras mutations and p16 and preproenkephalin (ppENK) promoter hypermethylation and their associations with cigarette smoking in pancreatic cancer patients.

METHODS

In plasma DNA of 83 patients with untreated primary pancreatic ductal adenocarcinoma, DNA hypermethylation was determined by methylation-specific polymerase chain reaction and K-ras codon 12 mutations by enriched-nested polymerase chain reaction followed by direct sequencing. Information on smoking exposure was collected by in-person interview. Pearson chi test and Fisher exact test were used in statistical analysis.

RESULTS

K-ras mutations, ppENK, and p16 promoter hypermethylation were detected in 32.5%, 29.3%, and 24.6% of the patients, respectively. Sixty-three percent (52/83) of patients exhibited at least one of the alterations. Smoking was associated with the presence of K-ras mutations (P = 0.003). A codon 12 G-to-A mutation was predominantly observed in regular smokers and in heavy smokers (pack-year of smoking > or =36). Smoking was not associated with p16 or ppENK hypermethylation.

CONCLUSIONS

These preliminary observations suggest that plasma DNA might be a useful surrogate in detecting genetic and epigenetic alterations of pancreatic cancer. The findings on the association between K-ras mutation and smoking were in consistency with previous studies. Further studies on environmental modulators of epigenetic changes in pancreatic cancer are warranted.

Acute suppuration of the pancreatic duct associated with pancreatic ductal obstruction due to pancreas carcinoma

Acute obstructive suppurative cholangitis is a well-known clinical entity; however, acute suppuration of the pancreatic duct in the setting of pancreatic ductal obstruction is an uncommon pancreatic disorder. We report a case of acute suppuration of the pancreatic duct without either a concomitant pancreatic abscess or an infected pseudocyst, presenting as acute relapsing pancreatitis. In this case, the underlying cause of suppuration of the pancreatic duct was pancreatic ductal obstruction and chronic pancreatitis secondary to pancreas head carcinoma along with infection of Escherichia coli. Endoscopic placement of a pancreatic stent resulted in an evacuation of grayish thick pus from the distal pancreatic duct with a dramatic improvement of the disease. This case proposes the concept that acute suppuration of the pancreatic duct is a complex process involving the chronically damaged pancreas, pancreatic outflow obstruction, and subsequent bacterial infection. Antibiotic treatment is effective but temporary; therefore, the immediate drainage of the infected pancreatic duct is mandatory.