Tessa Y.S. Le Large

Molecular Mechanisms Underlying the Role of MicroRNAs in the Chemoresistance of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is an extremely severe disease where the mortality and incidence rates are almost identical. This is mainly due to late diagnosis and limited response to current treatments. The tumor macroenvironment/microenvironment have been frequently reported as the major contributors to chemoresistance in PDAC, preventing the drugs from reaching their intended site of action (i.e., the malignant duct cells). However, the recent discovery of microRNAs (miRNAs) has provided new directions for research on mechanisms underlying response to chemotherapy. Due to their tissue-/disease-specific expression and high stability in tissues and biofluids, miRNAs represent new promising diagnostic and prognostic/predictive biomarkers and therapeutic targets. Furthermore, several studies have documented that selected miRNAs, such as miR-21 and miR-34a, may influence response to chemotherapy in several tumor types, including PDAC. In this review, we summarize the current knowledge on the role of miRNAs in PDAC and recent advances in understanding their role in chemoresistance through multiple molecular mechanisms.

BamHI-A rightward frame 1, an Epstein-Barr virus-encoded oncogene and immune modulator.

Epstein–Barr virus (EBV) causes several benign and malignant disorders of lymphoid and epithelial origin. EBV‐related tumors display distinct patterns of viral latent gene expression, of which the BamHI‐A rightward frame 1 (BARF1) is selectively expressed in carcinomas, regulated by cellular differentiation factors including ΔNp63α. BARF1 functions as a viral oncogene, immortalizing and transforming epithelial cells of different origin by acting as a mitogenic growth factor, inducing cyclin‐D expression, and up‐regulating antiapoptotic Bcl‐2, stimulating host cell growth and survival. In addition, secreted hexameric BARF1 has immune evasive properties, functionally corrupting macrophage colony stimulating factor, as supported by recent functional and structural data. Therefore, BARF1, an intracellular and secreted protein, not only has multiple pathogenic functions but also can function as a target for immune responses. Deciphering the role of BARF1 in EBV biology will contribute to novel diagnostic and treatment options for EBV‐driven carcinomas. Herein, we discuss recent insights on the regulation of BARF1 expression and aspects of structure‐function relating to its oncogenic and immune suppressive properties.

Swarm Intelligence-Enhanced Detection of Non-Small-Cell Lung Cancer Using Tumor-Educated Platelets

Summary Blood-based liquid biopsies, including tumor-educated blood platelets (TEPs), have emerged as promising biomarker sources for non-invasive detection of cancer. Here we demonstrate that particle-swarm optimization (PSO)-enhanced algorithms enable efficient selection of RNA biomarker panels from platelet RNA-sequencing libraries (n = 779). This resulted in accurate TEP-based detection of early- and late-stage non-small-cell lung cancer (n = 518 late-stage validation cohort, accuracy, 88%; AUC, 0.94; 95% CI, 0.92–0.96; p < 0.001; n = 106 early-stage validation cohort, accuracy, 81%; AUC, 0.89; 95% CI, 0.83–0.95; p < 0.001), independent of age of the individuals, smoking habits, whole-blood storage time, and various inflammatory conditions. PSO enabled selection of gene panels to diagnose cancer from TEPs, suggesting that swarm intelligence may also benefit the optimization of diagnostics readout of other liquid biopsy biosources.

Epstein-Barr Virus-Encoded BARF1 Protein is a Decoy Receptor for Macrophage Colony Stimulating Factor and Interferes with Macrophage Differentiation and Activation

Epstein-Barr virus (EBV), like many other persistent herpes viruses, has acquired numerous mechanisms for subverting or evading immune surveillance. This study investigates the role of secreted EBV-encoded BARF1 protein (sBARF1) in creating an immune evasive microenvironment. Wild-type consensus BARF1 was expressed in the human 293 cell line and purified. This native hexameric sBARF1 had inhibitory capacity on macrophage colony stimulating factor (M-CSF)-stimulated, and not on granulocyte macrophage-colony stimulating factor (GM-CSF)-stimulated growth and differentiation of myeloid cells. Antibodies specific to hexameric sBARF1 were able to block this effect. M-CSF was shown to interact with sBARF1 via the protruding N-terminal loops involving Val38 and Ala84. Each BARF1 hexamer was capable of binding three M-CSF dimers. Mutations in the BARF1 loops greatly affected M-CSF interaction, and showed loss of growth inhibition. Analysis of the activation state of the M-CSF receptor c-fms and its downstream kinase pathways showed that sBARF1 prevented M-CSF-induced downstream phosphorylation. Since M-CSF is an important factor in macrophage differentiation, the effect of sBARF1 on the function of monocyte-derived macrophages was evaluated. sBARF1 affected overall survival and morphology and significantly reduced expression of macrophage differentiation surface markers such as CD14, CD11b, CD16, and CD169. Macrophages differentiating in the presence of sBARF1 showed impaired responses to lipopolysaccharide and decreased oxygen radical formation as well as reduced phagocytosis of apoptotic cells. In conclusion, EBV sBARF1 protein is a potent decoy receptor for M-CSF, hampering the function and differentiation of macrophages. These results suggest that sBARF1 contributes to the modulation of immune responses in the microenvironment of EBV-positive carcinomas.

FOLFIRINOX and translational studies: Towards personalized therapy in pancreatic cancer

Pancreatic cancer is an extremely aggressive disease; although progress has been made in the last few years, the prognosis of these patients remains dismal. FOLFIRINOX is now considered a standard treatment in first-line setting, since it demonstrated an improved overall and progression-free survival vs gemcitabine alone. However, the enthusiasm over the benefit of this three-drug regimen is tempered by the associated increased toxicity profile, and many efforts have been made to improve the feasibility of this schedule. After a more recent phase III trial showing an improved outcome over gemcitabine, the combination of gemcitabine/nab-paclitaxel emerged as another standard first-line treatment. However, this treatment is also associated with more side effects. In addition, despite initial promising data on the predictive role of SPARC levels, recent studies showed that these levels are not associated with nab-paclitaxel efficacy. The choice to use this treatment over FOLFIRINOX is therefore a topic of debate, also because no validated biomarkers to guide FOLFIRINOX treatment are available. In the era of actionable mutations and target agents it would be desirable to identify molecular factors or biomarkers to predict response to therapy in order to maximize the efficacy of treatment and avoid useless toxic effects for non-responding patients. However, until today the milestone of treatment for pancreatic cancer remains chemotherapy combinations, without predictive or monitoring tools existing to optimize therapy. This review analyzes the state-of-the-art treatments, promises and limitations of targeted therapies, ongoing trials and future perspectives, including potential role of microRNAs as predictive biomarkers.

AKT1 and SELP Polymorphisms Predict the Risk of Developing Cachexia in Pancreatic Cancer Patients

Pancreatic ductal adenocarcinoma (PDAC) patients have the highest risk of developing cachexia, which is a direct cause of reduced quality of life and shorter survival. Novel biomarkers to identify patients at risk of cachexia are needed and might have a substantial impact on clinical management. Here we investigated the prognostic value and association of SELP-rs6136, IL6-rs1800796 and AKT1-rs1130233 polymorphisms with cachexia in PDAC. Genotyping was performed in DNA from blood samples of a test and validation cohorts of 151 and 152 chemo-naive locally-advanced/metastatic PDAC patients, respectively. The association of SELP-rs6136, IL6-rs1800796 and AKT1-rs1130233 polymorphisms with cachexia as well as the correlation between cachexia and the candidate polymorphisms and overall survival were analyzed. Akt expression and phosphorylation in muscle biopsies were evaluated by specific ELISA assays. SELP-rs6136-AA and AKT1-rs1130233-AA/GA genotypes were associated with increased risk of developing cachexia in both cohorts (SELP: p = 0.011 and p = 0.045; AKT1: p = 0.004 and p = 0.019 for the first and second cohorts, respectively), while patients carrying AKT1-rs1130233-GG survived significantly longer (p = 0.002 and p = 0.004 for the first and second cohorts, respectively). In the multivariate analysis AKT1-rs1130233-AA/GA genotypes were significant predictors for shorter survival, with an increased risk of death of 1.7 (p = 0.002) and 1.6 (p = 0.004), in the first and second cohorts, respectively. This might be explained by the reduced phosphorylation of Akt1 in muscle biopsies from patients harboring AKT1-rs1130233-AA/GA (p = 0.003), favoring apoptosis induction. In conclusion, SELP and AKT1 polymorphisms may play a role in the risk of cachexia and death in PDAC patients, and should be further evaluated in larger prospective studies.

Circulating microRNAs as diagnostic biomarkers for pancreatic cancer.

There is an urgent need for novel and reliable biomarkers for the diagnosis and prognostication of pancreatic ductal adenocarcinoma (PDAC). Circulating microRNAs (miRNAs) have been extensively profiled in PDAC blood samples, but few studies have performed adequate validation of candidate markers. The evaluated study by Xu et al. investigated pre-operative plasma miRNAs from PDAC patients over three phases and three surgical centers. They revealed miR-486-5p and miR-938 were able to discriminate PDAC patients from healthy controls and those with chronic pancreatitis. The diagnostic ability of miR-486-5p for identifying PDAC from healthy controls was comparable to that of CA 19-9. This study provides further evidence for the use of blood-based miRNAs as diagnostic biomarkers in PDAC. However, as these have not been identified in previous studies these require further validation and methodology needs to be standardized if these are ever to be used in the clinic.

Surveillance strategy for small asymptomatic non-functional pancreatic neuroendocrine tumors – a systematic review and meta-analysis

BACKGROUND Non-functional pancreatic neuroendocrine tumors (NF-PNET) are rare neoplasms being increasingly diagnosed. Surgical treatment or expectant management are both suggested for small NF-PNETs. The aim of this study was to evaluate the outcome of surveillance strategy for small NF-PNETs. METHODS A systematic search was performed up to March 2016 in MEDLINE, EMBASE and the Cochrane Library according to the PRISMA guidelines. Data was pooled using the random-effects model. RESULTS Nine articles including 344 patients with sporadic and 64 patients with MEN1 related NF-PNET were selected. Tumor growth was observed in 22% and 52%, development of metastases were reported on 0% and 9%, and rate of secondary surgical resection was 12% and 25% in patients with sporadic or MEN1 related NF-PNETs, respectively. All metastases (1 distant, 4 nodal) were reported by a single study in patients with MEN1. Reason for secondary surgery was tumor growth in half of patients undergoing surgery. DISCUSSION Expectant management of small asymptomatic, sporadic, NF-PNETs could be a reasonable option in highly selected patients. However, the level of evidence is low and longer follow-up is needed to identify patients could benefit from upfront surgery instead of expectant treatment.

Outcomes and Treatment Options for Duodenal Adenocarcinoma: A Systematic Review and Meta-Analysis

BackgroundDuodenal adenocarcinoma (DA) is a rare tumor for which survival data per treatment modality and disease stage are unclear. This systematic review and meta-analysis aims to summarize the current literature on patient outcome after surgical, (neo)adjuvant, and palliative treatment in patients with DA.MethodsA systematic search was performed according to the preferred reporting items for systematic reviews and meta-analyses guidelines, to 25 April 2017. Primary outcome was overall survival (OS), specified for treatment strategy or disease stage. Random-effects models were used for the calculation of pooled odds ratios per treatment modality. Included papers were also screened for prognostic factors.ResultsA total of 26 observational studies, comprising 6438 patients with DA, were included. Of these, resection with curative intent was performed in 71% (range 53–100%) of patients, and 29% received palliative treatment (range 0–61%). The pooled 5-year OS rate was 46% after curative resection, compared with 1% in palliative-treated patients (OR 0.04, 95% confidence interval [CI] 0.02–0.09, p < 0.0001). Both segmental resection and pancreaticoduodenectomy allowed adequate assessment of lymph node involvement and resulted in similar OS. Lymph node involvement correlated with worse OS (pooled 5-year survival rate 21% for nodal metastases vs. 65% for node-negative disease; OR 0.17, 95% CI 0.11–0.27, p < 0.0001). In the current literature, no survival benefit for adjuvant therapy after curative resection was found.ConclusionResection with curative intent, either pancreaticoduodenectomy or segmental resection, and lack of nodal metastases, favors survival for DA. Further studies exploring multimodality (neo)adjuvant therapy are warranted to investigate their benefit.

Bioinformatic analysis reveals pancreatic cancer molecular subtypes specific to the tumor and the microenvironment.

ABSTRACT Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease characterized by a dense desmoplastic reaction surrounding malignant epithelial cells. Interaction between the epithelial and stromal compartments is suggested to enhance its aggressive nature. Indeed, therapies targeting the stroma, as well as the tumor cells, may improve survival outcomes for patients. The evaluated study by Moffitt et al. used bioinformatic techniques to separate gene expression patterns of normal tissues from PDAC and stroma in a large cohort of samples. The researchers identified two different subtypes of PDAC (‘classical’ and ‘basal-like’) and surrounding stroma (‘normal’ and ‘activated’). The basal-like subtype was associated with worse prognosis and a trend towards better response to adjuvant therapy. Hopefully, the molecular stratification of PDAC will potentially allow more personalized treatment strategies and guide clinical decision making.