Tarkan Jäger

Epigenetics and pancreatic cancer: Pathophysiology and novel treatment aspects

An improvement in pancreatic cancer treatment represents an urgent medical goal. Late diagnosis and high intrinsic resistance to conventional chemotherapy has led to a dismal overall prognosis that has remained unchanged during the past decades. Increasing knowledge about the molecular pathogenesis of the disease has shown that genetic alterations, such as mutations of K-ras, and especially epigenetic dysregulation of tumor-associated genes, such as silencing of the tumor suppressor p16(ink4a), are hallmarks of pancreatic cancer. Here, we describe genes that are commonly affected by epigenetic dysregulation in pancreatic cancer via DNA methylation, histone acetylation or miRNA (microRNA) expression, and review the implications on pancreatic cancer biology such as epithelial-mesenchymal transition, morphological pattern formation, or cancer stem cell regulation during carcinogenesis from PanIN (pancreatic intraepithelial lesions) to invasive cancer and resistance development. Epigenetic drugs, such as DNA methyltransferases or histone deactylase inhibitors, have shown promising preclinical results in pancreatic cancer and are currently in early phases of clinical development. Combinations of epigenetic drugs with established cytotoxic drugs or targeted therapies are promising approaches to improve the poor response and survival rate of pancreatic cancer patients.

Cumulative incidence of permanent stoma after sphincter preserving low anterior resection of mid and low rectal cancer.

BACKGROUND: Changes in the treatment of rectal cancer during the past decades have led to an increase in sphincter preservation with a consecutive decline in abdominoperineal resection rates. OBJECTIVE: The aim of this study was to analyze the cumulative incidence of permanent stoma in patients undergoing sphincter-preserving resection of mid and low rectal cancer. DESIGN: This study is a retrospective analysis of prospectively collected data. SETTINGS: This study was conducted at a tertiary referral cancer hospital. PATIENTS: From 2003 to 2010, 125 patients with primary mid and low rectal cancer who underwent sphincter-preserving low anterior resection were included. MAIN OUTCOME MEASURES: The occurrence of a permanent stoma over time was investigated by using a Cox proportional hazards regression model and competing-risk models, with death as a competing risk. The risk factors were assessed by computing HRs and a Cox proportional hazards regression. RESULTS: After a median follow-up time of 61 months (range, 22–113), 15 of 125 patients ended up with a permanent stoma, accounting for a 5-year cumulative incidence of 6% (95% CI, 4%–11%). The reasons for obtaining a permanent stoma were anastomotic leakage (60%, 9/15), intractable fecal incontinence (27%, 4/15), and local recurrence (13%, 2/15). The Cox proportional hazards regression identified anastomotic leakage (HR, 6.10; 95% CI, 2.23–16.71; p = 0.0004) and coloanal anastomosis (HR, 4.31; 95% CI, 1.49–12.47; p = 0.007) as statistically significant risk factors. LIMITATIONS: Because of the small number of events in this sample, further investigations with a larger number of patients are required. Fecal incontinence was assessed by patient self-reported data without the use of a validated score. CONCLUSION: The 5-year cumulative incidence of a permanent stoma was 6%. Anastomotic leakage and coloanal anastomosis were identified as risk factors. These details should be considered before sphincter-preserving surgery.

Robust linear regression model of Ki-67 for mitotic rate in gastrointestinal stromal tumors.

Risk stratification of gastrointestinal stromal tumors (GISTs) by tumor size, lymph node and metastasis status is crucially affected by mitotic activity. To date, no studies have quantitatively compared mitotic activity in hematoxylin and eosin (H&E)-stained tissue sections with immunohistochemical markers, such as phosphohistone H3 (PHH3) and Ki-67. According to the TNM guidelines, the mitotic count on H&E sections and immunohistochemical PHH3-stained slides has been assessed per 50 high-power fields of 154 specimens of clinically documented GIST cases. The Ki-67-associated proliferation rate was evaluated on three digitalized hot spots using image analysis. The H&E-based mitotic rate was found to correlate significantly better with Ki-67-assessed proliferation activity than with PHH3-assessed proliferation activity (r=0.780; P<0.01). A linear regression model (analysis of variance; P<0.001) allowed reliable predictions of the H&E-associated mitoses based on the Ki-67 expression alone. Additionally, the Ki-67-associated proliferation revealed a higher and significant impact on the recurrence and metastasis rate of the GIST cases than by the classical H&E-based mitotic rate. The results of the present study indicated that the mitotic rate may be reliably and time-efficiently estimated by immunohistochemistry of Ki-67 using only three hot spots.

Comprehensive immunohistochemical analysis of histone deacetylases in pancreatic neuroendocrine tumors: HDAC5 as a predictor of poor clinical outcome ☆ ☆☆

Epigenetic factors contribute to carcinogenesis, tumor promotion, and chemoresistance. Histone deacetylases (HDACs) are epigenetic regulators that primarily cause chromatin compaction, leading to inaccessibility of promoter regions and eventually gene silencing. Many cancer entities feature overexpression of HDACs. Currently, the role of HDACs in pancreatic neuroendocrine tumors (pNETs) is unclear. We analyzed the expression patterns of all HDAC classes (classes I, IIA, IIB, III, and IV) in 5 human tissue microarrays representing 57 pNETs resected between 1997 and 2013 and corresponding control tissue. All pNET cases were characterized clinically and pathologically according to recent staging guidelines. The investigated cases included 32 (56.1%) female and 25 (43.9%) male pNET patients (total n=57, 47.4% immunohistochemically endocrine positive). Immunohistochemical profiling revealed a significant up-regulation of all HDAC classes in pNET versus control, with different levels of intensity and extensity ranging from 1.5- to >7-fold up-regulation. In addition, expression of several HDACs (HDAC1, HDAC2, HDAC5, HDAC11, and Sirt1) was significantly increased in G3 tumors. Correlation analysis showed a significant association between the protein expression of HDAC classes I, III, and IV and rate of the pHH3/Ki-67-associated mitotic and proliferation index. Furthermore, especially HDAC5 proved as a negative predictor of disease-free and overall survival in pNET patients. Overall, we demonstrate that specific members of all 4 HDAC classes are heterogeneously expressed in pNET. Moreover, expression of HDACs was associated with tumor grading, proliferation markers, and patient survival, therefore representing interesting new targets in pNET treatment.

Thoughts on investigational hedgehog pathway inhibitors for the treatment of cancer

Department of Surgery, Paracelsus Medical University, Salzburger Landeskliniken (SALK), Salzburg, Austria; Experimental Medicine Oncology, Bayer Pharma AG, Berlin, Germany; Department of Gastroenterology CBF, Charité University Medicine Berlin, Berlin, Germany; Department of Internal Medicine I, Paracelsus Medical University, Salzburger Landeskliniken (SALK), Salzburg, Austria; Laboratory for Tumour Biology and Experimental Therapies (TREAT), Institute of Physiology and Pathophysiology, Paracelsus Medical University, Salzburg, Austria; Faculty of Chemistry, University of Vienna, Vienna, Austria; Institute of Pathology, Paracelsus Medical University, Salzburger Landeskliniken (SALK), Salzburg, Austria; Cancer Cluster Salzburg (CCS), Salzburg, Austria

Differential role of Hedgehog signaling in human pancreatic (patho-) physiology: An up to date review.

Since the discovery of the Hedgehog (Hh) pathway in drosophila melanogaster, our knowledge of the role of Hh in embryonic development, inflammation, and cancerogenesis in humans has dramatically increased over the last decades. This is the case especially concerning the pancreas, however, real therapeutic breakthroughs are missing until now. In general, Hh signaling is essential for pancreatic organogenesis, development, and tissue maturation. In the case of acute pancreatitis, Hh has a protective role, whereas in chronic pancreatitis, Hh interacts with pancreatic stellate cells, leading to destructive parenchym fibrosis and atrophy, as well as to irregular tissue remodeling with potency of initiating cancerogenesis. In vitro and in situ analysis of Hh in pancreatic cancer revealed that the Hh pathway participates in the development of pancreatic precursor lesions and ductal adenocarcinoma including critical interactions with the tumor microenvironment. The application of specific inhibitors of components of the Hh pathway is currently subject of ongoing clinical trials (phases 1 and 2). Furthermore, a combination of Hh pathway inhibitors and established chemotherapeutic drugs could also represent a promising therapeutic approach. In this review, we give a structured survey of the role of the Hh pathway in pancreatic development, pancreatitis, pancreatic carcinogenesis and pancreatic cancer as well as an overview of current clinical trials concerning Hh pathway inhibitors and pancreas cancer.

Thermographic real-time-monitoring of surgical radiofrequency and microwave ablation in a perfused porcine liver model

Radiofrequency ablation (RFA) and microwave ablation (MWA) are currently the dominant modalities to treat unresectable liver tumors. Monitoring the ablation process with b-mode-sonography is often hampered by artefacts. Furthermore, vessels may cause cooling in the adjacent tumor target (heat-sink-effect) with risk of local recurrence. The present study evaluated infrared-thermography to monitor surgical RFA/MWA and detect heat-sink-effects in real-time. RFA and MWA of perfused porcine livers was conducted at peripheral and central-vessel-adjacent locations, and monitored by real-time thermography. Ablation was measured and evaluated by gross pathology. The mean time for ablation was significantly longer in RFA compared with MWA (8 vs. 2 min). Although mean macroscopic ablation diameter was similar (RFA, 3.17 cm; MWA, 3.38 cm), RFA showed a significant heat-sink-effect compared with MWA. The surface temperature during central RFA near vessels was 1/3 lower compared with peripheral RFA (47.11±8.35°C vs. 68.72±12.70°C; P<0.001). There was no significant difference in MWA (50.52±8.35°C vs. 50.18±10.35°C; P=0.74). In conclusion, thermography is suitable to monitor the correct ablation with MWA and RFA. The results of the current study demonstrated a significant heat-sink-effect for RFA, but not MWA near vessels. MWA reaches consistent surface temperatures much faster than RFA. With further in vivo validation, thermography may be useful to ensure appropriate ablation particularly near vulnerable or vascular structures.

Applicability of American Joint Committee on Cancer and College of American Pathologists Regression Grading System in Rectal Cancer

BACKGROUND: Different tumor grading systems have been proposed to predict the association between tumor response and clinical outcome after preoperative chemoradiotherapy in patients with rectal cancer. The American Joint Committee on Cancer and College of American Pathologists regression grading system was recommended as the standard tumor regression grading system for rectal adenocarcinoma. OBJECTIVE: This study evaluated the clinical applicability of the American Joint Committee on Cancer and College of American Pathologists regression grading system in neoadjuvant-treated patients with rectal cancer. DESIGN: This is a retrospective cohort study based on clinical data from a prospectively maintained colorectal cancer database. SETTINGS: This study was performed at a single tertiary referral center. PATIENTS: A total of 144 patients with primary locally advanced mid-to-low rectal adenocarcinoma who underwent preoperative long-course chemoradiotherapy and total mesorectal excision between 2003 and 2012 were included. MAIN OUTCOMES MEASURES: The primary outcome measures were the 5-year overall survival rate, the relapse-free survival rate, the cancer-specific survival rate, and cumulative recurrence rates. RESULTS: Of the 144 patients, 16 (11%) were diagnosed as American Joint Committee on Cancer and College of American Pathologists regression grade 0, 43 patients (30%) as grade 1, 61 patients (42%) as grade 2, and 25 patients (17%) as grade 3. After a median follow-up time of 83 months (range, 3 to 147 mo), 5-year survival estimates for grades 0, 1, 2, and 3, were 93%, 77%, 81%, and 54% for overall survival (p = 0.006); 93%, 82%, 75%, and 55% for relapse-free survival (p = 0.03); and 100%, 86%, 89%, and 63% for cancer-specific survival (p = 0.006). The multivariate Cox regression analyses confirmed the American Joint Committee on Cancer and College of American Pathologists regression grading system as a prognostic factor for overall (p = 0.04), relapse-free (p = 0.02), and cancer-specific survival (p = 0.04). LIMITATIONS: This was a retrospective study. CONCLUSIONS: Our study findings confirm the clinical relevance and applicability of the American Joint Committee on Cancer and College of American Pathologists regression grade system as a predictive factor for patients with rectal cancer. See Video Abstract at http://links.lww.com/DCR/A320.

Intrathoracic major duodenal papilla with transhiatal herniation of the pancreas and duodenum: A case report and review of the literature

Transhiatal herniation of the pancreas is an extremely rare condition. In the published literature we found only eleven cases reported in the period of 1958 to 2011. A coincidental hiatal herniation of the duodenum is described in two cases only. To our knowledge, we report the first case with a hiatal herniation of the complete duodenum and proximal pancreas presenting an intrathoracic major duodenal papilla with consecutive intrahepatic and extrahepatic cholestasis. A 72-year-old Caucasian woman was admitted to our department with a hiatal hernia grade IV for further evaluation. According to our recommendation of surgical hernia repair soon after the diagnosis of a transhiatal herniation of the proximal pancreas and entire duodenum, we had to respect the declared intention of the patient for a conservative procedure. So we were forced to wait for surgical repair within an emergency situation complicated by a myocardial infarction and reduced general condition. We discuss the therapeutic decision making process and a complete literature review of this rare entity.

Pharmacological Inhibition of Class IIA HDACs by LMK-235 in Pancreatic Neuroendocrine Tumor Cells

Histone deacetylases (HDACs) play a key role in epigenetic mechanisms in health and disease and their dysfunction is implied in several cancer entities. Analysis of expression patterns in pancreatic neuroendocrine tumors (pNETs) indicated HDAC5 to be a potential target for future therapies. As a first step towards a possible treatment, the aim of this study was to evaluate the in vitro cellular and molecular effects of HDAC5 inhibition in pNET cells. Two pNET cell lines, BON-1 and QGP-1, were incubated with different concentrations of the selective class IIA HDAC inhibitor, LMK-235. Effects on cell viability were determined using the resazurin-assay, the caspase-assay, and Annexin-V staining. Western Blot and immunofluorescence microscopy were performed to assess the effects on HDAC5 functionality. LMK-235 lowered overall cell viability by inducing apoptosis in a dose- and time-dependent manner. Furthermore, acetylation of histone-H3 increased with higher LMK-235 concentrations, indicating functional inhibition of HDAC4/5. Immunocytochemical analysis showed that proliferative activity (phosphohistone H3 and Ki-67) decreased at highest concentrations of LMK-235 while chromogranin and somatostatin receptor 2 (SSTR2) expression increased in a dose-dependent manner. HDAC5 expression was found to be largely unaffected by LMK-235. These findings indicate LMK-235 to be a potential therapeutic approach for the development of an effective and selective pNET treatment.