Pancreatic CT density is an optimal imaging biomarker for earlier detection of malignancy in the pancreas with intraductal papillary mucinous neoplasm

BackgroundIntraductal papillary mucinous neoplasms (IPMNs) are typically detected as incidental findings by computed tomography (CT); however, the conventional surveillance is not valid for the early detection of concomitant pancreatic cancer. The pancreas of IPMN is often accompanied by fatty infiltration in the parenchyma, and pancreatic fatty infiltration could be evaluated by pancreatic CT density (pancreatic index, PI). We aimed to investigate whether PI could be an imaging biomarker for the early prediction of malignancies in the pancreas with IPMN.MethodsTwo different cohorts were investigated. (Investigation cohort): A total of 1137 patients with initially low-risk IPMN were compensated by initial IPMN findings, and 2 groups (malignancy/possible benign, 50 cases each) were investigated for yearly changes in PI and for the cutoff value of PI indicating the development of malignancies. (Validation cohort): To validate the cutoff value, 256 patients radiologically suspected of having IPMNs were investigated.Results(Investigation-cohort): The malignancy group showed a gradual decrease in PI every year, and PI significantly differed among the 2 groups 1 year prior to the last investigation. The cutoff value of PI was set at 0.65. (Validation-cohort): A total of 55% of the patients with a PI below the cutoff value had malignancy in the pancreas, including concomitant pancreatic cancer, and the cutoff value was the most significant risk factors for the development of malignancies in the pancreas compared to the conventional risk factors for IPMN.ConclusionsDecreasing PI would be an optimal imaging biomarker for earlier detection of malignancies in the pancreas with IPMN.     

The RNA‐binding protein MEX3A is a prognostic factor and regulator of resistance to gemcitabine in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer. Most patients present with advanced disease at diagnosis, which only permits palliative chemotherapeutic treatments. RNA dysregulation is a hallmark of most human cancers, including PDAC. To test the impact of RNA processing dysregulation on PDAC pathology, we performed a bioinformatics analysis to identify RNA‐binding proteins (RBPs) associated with prognosis. Among the 12 RBPs associated with progression‐free survival, we focused on MEX3A because it was recently shown to mark an intestinal stem cell population that is refractory to chemotherapeutic treatments, a typical feature of PDAC. Increased expression of MEX3A was correlated with higher disease stage in PDAC patients and with tumor development in a mouse model of PDAC. Depletion of MEX3A in PDAC cells enhanced sensitivity to chemotherapeutic treatment with gemcitabine, whereas its expression was increased in PDAC cells selected upon chronic exposure to the drug. RNA‐sequencing analyses highlighted hundreds of genes whose expression is sensitive to MEX3A expression, with significant enrichment in cell cycle genes. MEX3A binds to its target mRNAs, like cyclin‐dependent kinase 6 (CDK6), and promotes their stability. Accordingly, knockdown of MEX3A caused a significant reduction in PDAC cell proliferation and in progression to the S phase of the cell cycle. These findings uncover a novel role for MEX3A in the acquisition and maintenance of chemoresistance by PDAC cells, suggesting that it may represent a novel therapeutic target for PDAC.

Abbreviations

CLIP

UV‐crosslink and RNA immunoprecipitation

DFS

disease‐free survival

DR

drug resistant

EMT

mesenchymal transition

MC

MITO‐Cre

MKC

MITO‐Kras‐Cre

PARG

poly (ADP‐ribose) glycohydrolase

PDAC

pancreatic ductal adenocarcinoma

PI

propidium iodide

RBPs

RNA‐binding proteins

RNA‐seq

RNA sequencing

RNP

ribonucleoprotein

TGCA

The Cancer Genome Atlas

     

Clinical impact of celiac ganglia metastasis upon pancreatic ductal adenocarcinoma

BackgroundPre-operative staging of pancreatic adenocarcinoma guides clinical decision making. Limited data indicate that metastasis to celiac ganglia (CG) correlates with poor prognosis. We investigated feasibility and safety of endoscopic ultrasound fine needle aspiration (EUS-FNA) detection of CG metastasis and its impact upon tumor stage, resectability, and survival in pancreatic ductal adenocarcinoma (PDAC).PatientsWe reviewed our prospectively maintained EUS and cytopathology databases to identify patients with FNA proven CG metastasis in patients with PDAC from 2004 to 2017. Clinical demographics, EUS, CT, MRI, cytopathology, cancer stage, and resectability data were analyzed. Survival of PDAC patients with CG metastasis was compared to the expected survival of PDAC patients of similar stage as reported by the United States National Cancer Database.ResultsTwenty-one patients with PDAC [median age 73 (IQR63-78); 14 (67%) female)], had CG metastasis confirmed by cytopathologic assessment. CG metastasis resulted in tumor upstaging relative to other EUS findings and cross sectional imaging findings in 12 (57%) and 15 (71%) patients, and converted cancers from resectable to unresectable relative to EUS and cross sectional imaging in 7 (37%) and 7 (37%) patients, respectively. In patients with PDAC, the survival of patients with CG metastasis was not significantly different from the overall survival (hazard ratio 0.71; 95% confidence interval 0.44, 1.13; p = 0.15).ConclusionsEUS-FNA may safely identify CG metastases. While CG metastasis upstaged and altered the resectability status among this cohort of patients with PDAC, the survival data with regard to PDAC suggest that this may be misguided.     

Circulating IL-35 in pancreatic ductal adenocarcinoma patients

IL-35 is a novel inhibitory cytokine that is mainly produced by regulatory T-cells (Tregs) and is required for Treg-mediated immunosuppression. However, the plasma levels of IL-35 in patients with pancreatic ductal adenocarcinoma (PDAC) have never been investigated. In this study, we found that plasma IL-35 levels more significantly increased in PDAC patients than in normal controls (134.53 ± 92.45 pg/mL vs. 14.26 ± 6.56 pg/mL). IL-35 mRNA levels were positively correlated with plasma IL-35 levels (EBI3, R = 0.925, p < 0.01; p35, R = 0.916, p < 0.01). Furthermore, IL-35 expression levels were associated with lymph node metastasis (p = 0.001) and late tumor stage (p = 0.002). For the resected patients, high IL-35 expression levels were associated with large tumor size (p < 0.01), higher TNM classification T staging (p < 0.05), and late tumor stage (p < 0.05). In conclusion, circulating IL-35 in PDAC patients significantly increased, suggesting that regulating the expression of IL-35 may provide a new possible target for the treatment of PDAC patients, especially for the resectable ones.     

Heat shock protein 47 confers chemoresistance on pancreatic cancer cells by interacting with calreticulin and IRE1α

Pancreatic ductal adenocarcinoma (PDAC) is one of the most chemoresistant cancers. An understanding of the molecular mechanism by which PDAC cells have a high chemoresistant potential is important for improvement of the poor prognosis of patients with PDAC. Here we show for the first time that disruption of heat shock protein 47 (HSP47) enhances the efficacy of the therapeutic agent gemcitabine for PDAC cells and that the efficacy is suppressed by reconstituting HSP47 expression. HSP47 interacts with calreticulin (CALR) and the unfolded protein response transducer IRE1α in PDAC cells. Ablation of HSP47 promotes both the interaction of CALR with sarcoplasmic/endoplasmic reticulum Ca²⁺‐ATPase 2 and interaction of IRE1α with inositol 1,4,5‐triphosphate receptor, which generates a condition in which an increase in intracellular Ca²⁺ level is prone to be induced by oxidative stimuli. Disruption of HSP47 enhances NADPH oxidase‐induced generation of intracellular reactive oxygen species (ROS) and subsequent increase in intracellular Ca²⁺ level in PDAC cells after treatment with gemcitabine, resulting in the death of PDAC cells by activation of the Ca²⁺/caspases axis. Ablation of HSP47 promotes gemcitabine‐induced suppression of tumor growth in PDAC cell‐bearing mice. Overall, these results indicated that HSP47 confers chemoresistance on PDAC cells and suggested that disruption of HSP47 may improve the efficacy of chemotherapy for patients with PDAC.     

Par-4 activation restrains EMT-induced chemoresistance in PDAC by attenuating MDM-2

BackgroundWe recently reported prostate apoptosis response 4 (Par-4), a potential tumor suppressor protein restrains epithelial-mesenchymal transition (EMT) properties and promotes mesenchymal-epithelial transition (MET) in invasive cancer cells by repressing Twist-1 promoter activity. Here, we demonstrate that genetic as well as pharmacological modulation of Par-4 by NGD16 (a small molecule antimetastatic agent), limits EMT-induced chemoresistance in aggressive cancer cells by suppressing MDM-2, a downstream effector of Twist-1.MethodsMatrigel invasion assay, gelatin degradation assay, cell scattering assay, MTT assay and colony formation assay were used to study the proliferation and migration abilities of invasive cancer cells. Immunoblotting, immunocytochemistry, and immunoprecipitation analysis were utilized for determining protein expression and protein-protein interaction. 4T1 aggressive mouse carcinoma model was employed to evaluate tumor growth and lung metastasis.ResultsTreatment of gemcitabine (nucleoside analogue anticancer agent) to pancreatic cancer (Panc-1, MiaPaca-2) and breast cancer (MDA-MB-231) cells amplified MDM-2 expression along with increase in EMT properties. Conversely, NGD16 boosted expression of tumor suppressor Par-4 and inhibited invasion and migration abilities of these cells. Moreover, induction of Par-4 effectively diminished MDM-2 along with pro-EMT markers, whereas, augmented the expression of epithelial markers. Furthermore, siRNA-mediated silencing of Par-4 divulged that NGD16 exerts its EMT inhibitory effects in a Par-4-dependent manner. Mechanistically, Par-4 activation provokes p53 by disrupting MDM-2-p53 interaction, which restored epithelial characteristics in cancer cells. Additionally, partial knockdown of MDM-2 through siRNA pronounced the anti-proliferative and anti-invasive effects of NGD16. Finally, NGD16 efficiently inhibited tumor growth and lung metastasis in mouse mammary carcinoma model without showing any undesirable effects.ConclusionOur findings unveil Par-4 as a key therapeutic target and NGD16 (the pharmacological modulator of Par-4) are potential tools to suppress EMT and associated chemoresistance, which could be exploited clinically for the treatment of aggressive cancers.     

Ring-enhancement pattern on contrast-enhanced CT predicts adenosquamous carcinoma of the pancreas: A matched case-control study

ObjectivesAdenosquamous carcinoma of the pancreas (ASC) is a rare malignant neoplasm of the pancreas, exhibiting both glandular and squamous differentiation. However, little is known about its imaging features. This study examined the imaging features of pancreatic ASC.MethodsWe evaluated images of contrast-enhanced computed tomography (CT) and endoscopic ultrasonography (EUS). As controls, solid pancreatic neoplasms matched in a 2:1 ratio to ASC cases for age, sex and tumor location were also evaluated.ResultsTwenty-three ASC cases were examined, and 46 solid pancreatic neoplasms (43 pancreatic ductal adenocarcinomas, two pancreatic neuroendocrine tumors and one acinar cell carcinoma) were matched as controls. Univariate analysis demonstrated significant differences in the outline and vascularity of tumors on contrast-enhanced CT in the ASC and control groups (P < 0.001 and P < 0.001, respectively). A smooth outline, cystic changes, and the ring-enhancement pattern on contrast-enhanced CT were seen to have significant predictive powers by stepwise forward logistic regression analysis (P = 0.044, P = 0.010, and P = 0.001, respectively). Of the three, the ring-enhancement pattern was the most useful, and its predictive diagnostic sensitivity, specificity, positive predictive value and negative predictive value for diagnosis of ASC were 65.2%, 89.6%, 75.0% and 84.3%, respectively.ConclusionsThese results demonstrate that presence of the ring-enhancement pattern on contrast-enhanced CT is the most useful predictive factor for ASC.     

Preclinical evaluation of near‐infrared (NIR) fluorescently labeled cetuximab as a potential tool for fluorescence‐guided surgery

The high rate of recurrence in patients with pancreatic ductal adenocarcinoma (PDAC) could be reduced by supporting the surgeons in discriminating healthy from diseased tissues with intraoperative fluorescence‐guidance. Here, we studied the suitability of Cetuximab, a therapeutic monoclonal antibody targeting the human epidermal growth factor receptor (EGFR), near‐infrared (NIR) fluorescently labeled as a new tool for fluorescence‐guided surgery. Distribution and binding of systemically injected Cetuximab Alexa Fluor 647 conjugate (Cetux‐Alexa‐647) and the co‐injected control human IgG Alexa Fluor 750 conjugate (hIgG‐Alexa‐750) was studied over 48 h by NIR fluorescence imaging in mice bearing human orthotopic AsPC‐1 and MIA PaCa‐2 PDAC tumors. Cetux‐Alexa‐647, but not the control hIgG‐Alexa‐750 fluorescence, was specifically detected in vivo in both primary pancreatic tumors with maximum fluorescence intensities at 24 h, and in metastases of AsPC‐1 tumors as small as 1 mm. Lifetime analysis and NIR fluorescence microscopy of tumor sections confirmed the binding specificity of Cetux‐Alexa‐647 to PDAC cells. Comparable results were obtained with Cetuximab conjugated to Alexa Fluor 750 dye (Cetux‐Alexa‐750). Fluorescence‐guided dissection, performed 24 h after injection of Cetuximab conjugated to IRDye 800CW (Cetux‐800CW), enabled a real‐time delineation of AsPC‐1 tumor margins, and small metastases. Odyssey scans revealed that only the vital part of the tumor, but not the necrotic part was stained with Cetux‐800CW. NIR fluorescently labeled Cetuximab may be a promising tool that can be applied for fluorescence‐guided surgery to visualize tumor margins and metastatic sites in order to allow a precise surgical resection.     

K-Ras4B/calmodulin/PI3Kα: A promising new adenocarcinoma-specific drug target?

Introduction: Decades of efforts have yet to yield a safe and effective drug to target KRAS-driven pancreatic, colorectal and lung cancers; particularly those driven by the highly oncogenic splice variant KRAS4B. K-Ras4B’s fairly smooth surface, cancer tissue/cell heterogeneity, tolerated lipid post-translational modification exchange, as well as drug-elicited toxicity present a daunting challenge.

Areas covered: Within this framework, hee we focus on a new adenocarcinoma-specific drug concept. Calmodulin (CaM) binds to K-Ras4B but not to the H-Ras or N-Ras isoforms. Physiologically, in calcium- and calmodulin-rich environments such as ductal tissues, calmodulin can sequester K-Ras4B from the membrane; in cancer, CaM/Ca²⁺ can replace the missing receptor tyrosine kinase (RTK) signal, acting to fully activate PI3Kα.

Expert opinion: An oncogenic GTP-bound K-Ras4B/CaM/PI3Kα complex is supported by available experimental and clinical data; therefore, targeting it may address a pressing therapeutic need. High resolution electron microscopy (EM) or crystal structure of the tripartite complex would allow orthosteric or allosteric drug discovery to disrupt the CaM/PI3Kα interface and thus Akt/mTOR signaling. However, since drug resistance is expected to develop, combining it with compensatory pathways, particularly those involved in cell-cycle control, appears a reasonable strategy.