Circulating tumour cells as a biomarker for diagnosis and staging in pancreatic cancer

BACKGROUND

Current diagnosis and staging of pancreatic ductal adenocarcinoma (PDAC) has important limitations and better biomarkers are needed to guide initial therapy. We investigated the performance of circulating tumour cells (CTCs) as an adjunctive biomarker at the time of disease presentation.

METHODS

Venous blood (VB) was collected prospectively from 100 consecutive, pre-treatment patients with PDAC. Utilising the microfluidic NanoVelcro CTC chip, samples were evaluated for the presence and number of CTCs. KRAS mutation analysis was used to compare the CTCs with primary tumour tissue. CTC enumeration data was then evaluated as a diagnostic and staging biomarker in the setting of PDAC.

RESULTS

We found 100% concordance for KRAS mutation subtype between primary tumour and CTCs in all five patients tested. Evaluation of CTCs as a diagnostic revealed the presence of CTCs in 54/72 patients with confirmed PDAC (sensitivity=75.0%, specificity=96.4%, area under the curve (AUROC)=0.867, 95% CI=0.798-0.935, and P<0.001). Furthermore, a cut-off of ⩾3 CTCs in 4 ml VB was able to discriminate between local/regional and metastatic disease (AUROC=0.885; 95% CI=0.800-0.969; and P<0.001).

CONCLUSION

CTCs appear to function well as a biomarker for diagnosis and staging in PDAC.

Removable esophageal stents have poor efficacy for the treatment of refractory benign esophageal strictures (RBES)

With the recent availability of removable esophageal stents, endoscopic stenting has been utilized to treat refractory benign esophageal strictures (RBES). The objective of this study was to review the feasibility and effectiveness of removable esophageal stents to treat RBES. Patients who received removable esophageal stents for the treatment of RBES at the institution between 2004-2010 using its stent implantation logs and endoscopic database were retrospectively identified. Patient demographics, stricture etiology and location, stent and procedure characteristics, and clinical outcomes were obtained. Twenty-five patients with a mean age of 70 (72% male) underwent initial stent placement; 24 were successful. Overall clinical success was achieved in five of the 19 patients (26%) ultimately undergoing stent removal. RBES etiologies included anastomotic (13), radiation (5), peptic (3), chemotherapy (1), scleroderma (1), and unknown (2). Alimaxx-E (Merit-Endotek, South Jordan, UT, USA) stents were placed in 20 patients and Polyflex (Boston Scientific, Natick, MA, USA) stents were used in five patients. Immediate complications included failed deployment (1) and chest pain (7). Five patients died prior to stent removal. Stent migration was found in 53% (10/19) of patients who underwent stent removal: nine required additional therapy and one had symptom resolution. Out of the nine patients without stent migration, five required additional therapy and four had symptom resolution. Although placement of removable esophageal stents for RBES is technically feasible, it is frequently complicated by stent migration and chest pain. In addition, few patients achieved long-term stricture resolution after initial stenting. In this study, most patients ultimately required repeated stenting and/or dilations to maintain relief of dysphagia.

Nrf2 deficiency promotes apoptosis and impairs PAX7/MyoD expression in aging skeletal muscle cells

Skeletal muscle redox homeostasis is transcriptionally regulated by nuclear erythroid-2-p45-related factor-2 (Nrf2). We recently demonstrated that age-associated stress impairs Nrf2-ARE (antioxidant-response element) transcriptional signaling. Here, we hypothesize that age-dependent decline or genetic ablation of Nrf2 leads to accelerated apoptosis and skeletal muscle degeneration. Under basal-physiological conditions, disruption of Nrf2 significantly downregulates antioxidants and causes oxidative stress. Surprisingly, Nrf2-null mice had enhanced antioxidant capacity identical to wild-type (WT) upon acute endurance exercise stress (AEES), suggesting activation of Nrf2-independent mechanisms (i.e., PGC1α) against oxidative stress. Analysis of prosurvival pathways in the basal state reveals decreased AKT levels, whereas p-p53, a repressor of AKT, was increased in Nrf2-null vs WT mice. Upon AEES, AKT and p-AKT levels were significantly (p < 0.001) increased (>10-fold) along with profound downregulation of p-p53 (p < 0.01) in Nrf2-null vs WT skeletal muscle, indicating the onset of prosurvival mechanisms to compensate for the loss of Nrf2 signaling. However, we found a decreased stem cell population (PAX7) and MyoD expression (differentiation) along with profound activation of ubiquitin and apoptotic pathways in Nrf2-null vs WT mice upon AEES, suggesting that compensatory prosurvival mechanisms failed to overcome the programmed cell death and degeneration in skeletal muscle. Further, the impaired regeneration was sustained in Nrf2-null vs WT mice after 1 week of post-AEES recovery. In an age-associated oxidative stress condition, ablation of Nrf2 results in induction of apoptosis and impaired muscle regeneration.

Nrf2 deficiency prevents reductive stress-induced hypertrophic cardiomyopathy

AIMS

Mutant protein aggregation (PA) cardiomyopathy (MPAC) is characterized by reductive stress (RS), PA (of chaperones and cytoskeletal components), and ventricular dysfunction in transgenic mice expressing human mutant CryAB (hmCryAB). Sustained activation of nuclear erythroid-2 like factor-2 (Nrf2) causes RS, which contributes to proteotoxic cardiac disease. The goals of this pre-clinical study were to (i) investigate whether disrupting Nrf2-antioxidant signalling prevents RS and rescues redox homeostasis in hearts expressing the mutant chaperone and (ii) elucidate mechanisms that could delay proteotoxic cardiac disease.

METHODS AND RESULTS

Non-transgenic (NTG), transgenic (TG) with MPAC and MPAC-TG:Nrf2-deficient (Nrf2-def) mice were used in this study. The effects of Nrf2 diminution (Nrf2±) on RS mediated MPAC in TG mice were assessed at 6-7 and 10 months of age. The diminution of Nrf2 prevented RS and prolonged the survival of TG mice (∼50 weeks) by an additional 20-25 weeks. The TG:Nrf2-def mice did not exhibit cardiac hypertrophy at even 60 weeks, while the MPAC-TG mice developed pathological hypertrophy and heart failure starting at 24-28 weeks of age. Aggregation of cardiac proteins was significantly reduced in TG:Nrf2-def when compared with TG mice at 7 months. Preventing RS and maintaining redox homeostasis in the TG:Nrf2-def mice ameliorated PA, leading to decreased ubiquitination of proteins.

CONCLUSION

Nrf2 deficiency rescues redox homeostasis, which reduces aggregation of mutant proteins, thereby delaying the proteotoxic pathological cardiac remodelling caused by RS and toxic protein aggregates.

Acute exercise stress activates Nrf2/ARE signaling and promotes antioxidant mechanisms in the myocardium

Oxidative stress has been implicated in the pathogenesis of cardiovascular diseases, including myocardial hypertrophy and infarction. Although impairment of antioxidant defense mechanisms has been thought to provoke oxidative stress-induced myocardial dysfunction, it has been difficult to clearly demonstrate. Nuclear erythroid 2 p45-related factor 2 (Nrf2) is a redox-sensitive, basic leucine zipper protein that regulates the transcription of several antioxidant genes. We previously reported that sustained activation of Nrf2 upregulates transcription of a number of endogenous antioxidants in the heart. Here, we show that acute exercise stress (AES) results in activation of Nrf2/ARE (antioxidant response element) signaling and subsequent enhancement of antioxidant defense pathways in wild-type (WT) mouse hearts, while oxidative stress, along with blunted defense mechanisms, was observed in Nrf2-/- mice. We also find that AES is associated with increased trans-activation of ARE-containing genes in exercised animals when compared to age-matched sedentary WT mice. However, enhanced oxidative stress in response to AES was observed in Nrf2-/- mice due to lower basal expression and marked attenuation of the transcriptional induction of several antioxidant genes. Thus, AES induces ROS and promotes Nrf2 function, but disruption of Nrf2 increases susceptibility of the myocardium to oxidative stress. Our findings suggest the basis for a nonpharmacological approach to activate Nrf2/ARE signaling, which might be a potential therapeutic target to protect the heart from oxidative stress-induced cardiovascular complications.

Endoscopic ultrasound-guided rendezvous for biliary access after failed cannulation

INTRODUCTION

Selective cannulation fails in approximately 3 % of endoscopic retrograde cholangiography (ERC) procedures. An endoscopic ultrasound-guided rendezvous technique (EUS - RV) may salvage failed cannulation. The aims of the current study were to determine the safety and efficacy of EUS - RV.

METHODS

A total of 40 patients underwent salvage EUS - RV. EUS - RV was attempted immediately after failed biliary cannulation. A dilated intra- or extra-hepatic biliary duct (IHBD or EHBD) was punctured from the stomach or the small intestine under EUS guidance followed by cholangiography and antegrade manipulation of the guide wire into the small intestine. Finally, the echoendoscope was exchanged for an appropriate endoscope and biliary cannulation was achieved over or adjacent to the guide wire.

RESULT

EUS-RV appears safe and effective and may be considered as a primary salvage technique after failed cannulation. Antegrade manipulation of the guide wire into the small intestine was achieved in 29 of 40 patients (73 %; EHBD 25 /31 and IHBD 4/9). The reasons for failure were inability to advance the guide wire through an obstruction or a native ampulla. Re-attempt at ERC immediately after failed EUS - RV was made in seven of the 11 patients, and was successful in four. The remaining seven patients underwent percutaneous drainage within 3 days. Complications occurred in five patients (13 %), including pancreatitis, abdominal pain, pneumoperitoneum, and sepsis/death, which was unlikely to be related to the procedure.

CONCLUSION

EUS - RV is safe and effective and should be considered as a primary salvage technique after failed cannulation. Immediate re-attempt at ERC after failed EUS - RV is warranted, as EUS-guided cholangiogram can facilitate biliary cannulation in some cases. Finally, prompt alternative biliary drainage should be available.