AZGP1 is a tumor suppressor in pancreatic cancer inducing mesenchymal-to-epithelial transdifferentiation by inhibiting TGF-β-mediated ERK signaling

Epithelial-to-mesenchymal transdifferentiation (EMT) mediated by transforming growth factor-β (TGF-β) signaling leads to aggressive cancer progression. In this study, we identified zinc-α2-glycoprotein (AZGP1, ZAG) as a tumor suppressor in pancreatic ductal adenocarcinoma whose expression is lost due to histone deacetylation. In vitro, ZAG silencing strikingly increased invasiveness of pancreatic cancer cells accompanied by the induction of a mesenchymal phenotype. Expression analysis of a set of EMT markers showed an increase in the expression of mesenchymal markers (vimentin (VIM) and integrin-α5) and a concomitant reduction in the expression of epithelial markers (cadherin 1 (CDH1), desmoplakin and keratin-19). Blockade of endogenous TGF-β signaling inhibited these morphological changes and the downregulation of CDH1, as elicited by ZAG silencing. In a ZAG-negative cell line, human recombinant ZAG (rZAG) specifically inhibited exogenous TGF-β-mediated tumor cell invasion and VIM expression. Furthermore, rZAG blocked TGF-β-mediated ERK2 phosphorylation. PCR array analysis revealed that ZAG-induced epithelial transdifferentiation was accompanied by a series of concerted cellular events including a shift in the energy metabolism and prosurvival signals. Thus, epigenetically regulated ZAG is a novel tumor suppressor essential for maintaining an epithelial phenotype.

Herpes simplex virus sepsis and acute liver failure

Acute liver failure is a life threatening disease mostly triggered by drug-induced or toxic liver damage or viral hepatitis. Herpes Simplex virus (HSV) hepatitis is rare and accounts for only 1% of all acute liver failures. The importance of HSV-induced acute liver failure is based on its extremely severe clinical course with lethality rates of almost 75%. HSV hepatitis is just one of several clinical manifestations of HSV sepsis leading more frequently to encephalitis, pneumonia and esophagitis. Local herpes infection or recurrence of dermal lesions (herpes labialis, herpes genitalis), however, is common and account for the high prevalence of HSV-1 or HSV-2 infection in adults. Another rare entity is visual dissemination, which mostly affects immunocompromised patients. Compromised cellular immunity is a major risk factor for HSV sepsis because of either primary infection or reactivation of occult chronic HSV infection. Delayed diagnosis without antiviral therapy significantly contributes to the unfavorable outcome. Typically, anicteric hepatitis is seen in patients with HSV hepatitis. Because of its low incidence, however, and the lack of dermal manifestations, HSV hepatitis is rarely considered in the context of acute liver failure. In addition, diagnostic tests might not always be available. Therefore, it is a generally accepted consensus to begin antiviral therapy pre-emptively with acyclovir in cases of acute liver failure of unknown origin, in which high urgency (HU) liver transplantation remains the only therapeutical option. Even in the case of early specific therapy, sepsis may prevail and the indication for HU transplantation must be evaluated carefully. The outcome after liver transplantation for HSV-induced liver failure with reported survival rates of more than 40% is good. Because of the risk of recurrence, lifelong prophylaxis with acyclovir is recommended.

The microenvironment in chronic pancreatitis and pancreatic cancer induces neuronal plasticity

BACKGROUND

Pancreatic neuropathy in chronic pancreatitis (CP) and pancreatic cancer (PCa) is characterized by pancreatic neuropathy, i.e. increased neural density and hypertrophy, which are associated with neuropathic pain. To better understand the mechanism of these neuropathic alterations, we aimed at achieving an in-vitro simulation of the intrapancreatic neuroplasticity.

METHODS

Dissociated myenteric plexus (MP) and dorsal root ganglia (DRG) neurons of newborn rats were treated with normal human pancreas (NP), CP or PCa tissue extracts. Furthermore, MP and DRG neurons were cultured in supernatants from different pancreatic cancer cell lines (PCC) and human pancreatic stellate cells (hPSC) obtained from either CP or PCa tissues. For analysis, the neurite density, outgrowth, neuronal branching capacity and perikaryonal size were quantified.

KEY RESULTS

Myenteric plexus and DRG neurons grown in CP and PCa tissue extracts built denser networks than in NP extracts. Both neuronal types showed a strong neurite outgrowth, more complex branching pattern and a somatic hypertrophy in CP and PCa extracts. Pancreatic cancer cell supernatants induced a prominent neurite outgrowth, increased neurite density and perikaryonal hypertrophy in MP and DRG neurons. Supernatants of CP-derived hPSC strongly stimulated neurite outgrowth. Glial density in MP cultures was strikingly increased by PCa tissue extracts.

CONCLUSIONS & INFERENCES

Intrapancreatic microenvironment in CP and PCa induces neuroplastic alterations under in-vitro conditions, leading to increased neural density and hypertrophy. Thus, due to its neurotrophic attributes, the intrapancreatic microenviroment in CP and PCa seems to be a key player in the generation of pancreatic neuropathy and neuroplasticity.

Liver transplantation in the rat: single-center experience with technique, long-term survival, and functional and histologic findings

OBJECTIVE

Orthotopic liver transplantation (OLT) in rats is frequently used as an experimental model. Numerous surgical techniques have been developed that enable the investigator to conduct clinically relevant studies. The objective of this study was to develop a rat model of acute and chronic rejection, to explicitly study technical modifications of vascular anastomoses with precision, and to examine histopathologic and functional changes in the graft.

MATERIALS AND METHODS

With DA-(RT1av1) rats as donors and Lewis-(RT1) rats as recipients, arterialized OLT was performed using a combined suture, cuff, and splint method. Recipients were divided into 5 groups: syngeneic control rats (group 1), allogeneic control rats (group 2), allogeneic OLT rats with low-dose tacrolimus (FK506) immunosuppression (group 3), allogeneic OLT rats with high-dose tacrolimus immunosuppression (group 4), and allogeneic OLT rats with high-dose tacrolimus immunosuppression and retrograde reperfusion via the infrahepatic caval vein (group 5). After OLT, serum parameters were determined and hepatic biopsy specimens were sampled. We examined the effects of acute rejection with or without immunosuppression therapy at histopathologic evaluation.

RESULTS

Liver grafts in syngeneic and allogeneic rats (groups 1, 2, 4, and 5) demonstrated normal serum parameters and histopathologic findings at 10 days after OLT, and 93% survival at 3 months. The simplified technique using 1 suture and 2 cuff anastomoses provided the best short- and long-term survival after OLT in all groups. Retrograde perfusion via the infrahepatic caval vein resulted in lower postoperative liver enzyme values.

CONCLUSION

The present model is feasible, enabling comprehensive preclinical experimental research on liver transplantation. Furthermore, we provide helpful instructions for learning this surgical technique.

[Middle segmental pancreatic resection: an organ-preserving option for benign lesions]

Benign and low malignant tumors of the middle pancreatic segment can be resected by extended pancreaticoduodenectomy or distal pancreatic resection. Both procedures involve unavoidably extensive loss of normal pancreatic parenchyma, leading to deteriorated endocrine and exocrine pancreatic function. Segmental pancreatic resection represents an organ-preserving surgical procedure. Normal pancreatic tissue can be preserved as only the tumor with a pancreatic segment is resected. Several reports confirm lower mortality and minimal risk of postoperative endocrine or exocrine insufficiency than with standard pancreatic resections. The indication should be limited exclusively to benign or low malignant pancreatic tumors, metastases from other tumors, and focal chronic pancreatitis, as this type of resection cannot be deemed oncologic. Segmental pancreatic resections are technically more demanding and therefore should be performed in experienced centers.

Expression of YPEL1 in pancreatic cancer cell lines and tissues

YPEL1 is a nuclear protein that is suggested to be involved in mesenchymal to epithelial-like transition during tissue development. Recently we have identified YPEL1 as a gene whose expression is deregulation in perineural invasive pancreatic cancer cells. In this study we assessed the expression of YPEL1 in normal and diseased pancreatic tissues and pancreatic cancer cell lines. Quantitative real time polymerase chain reaction was used to analyze the expression of YPEL1 mRNA in nine cultured pancreatic cancer cell lines and pancreatic bulk tissues of the normal pancreas (n=19), chronic pancreatitis (n=19) and pancreatic adenocarcinoma tissues (n=31). Quantitative real time polymerase chain reaction analysis revealed a significant down-regulation of YPEL1 mRNA expression in pancreatic adenocarcinoma tissues compared to normal tissues (54.1+/-5.2 vs. 85.8+/-14.1 copies/10,000 copies cpb) and low expression of this gene indicated a tendency for better survival of pancreatic cancer patients (16 vs. 13 months; p=0.17). Expression of YPEL1 mRNA was present in all tested pancreatic cancer cell lines with comparably low to moderate expression levels of 4.3 - 88.0 copies/10,000 copies cpb. Reduced expression of YPEL1 in pancreatic cancer might be related to perineural invasion. and prognosis. YPEL1 might be an important factor during the development and malignant transformation of tissues. Further studies are required to better assess the role of human YPEL1 in pancreatic cancer pathogenesis.

Systematic review and meta-analysis of prophylactic gastroenterostomy for unresectable advanced pancreatic cancer

BACKGROUND

The value of prophylactic gastroenterostomy (usually combined with a biliary bypass) in patients with unresectable cancer of the pancreatic head is controversial.

METHODS

A systematic review of retrospective and prospective studies, and a meta-analysis of prospective studies, on the use of prophylactic gastroenterostomy for unresectable pancreatic cancer were performed.

RESULTS

Analysis of retrospective studies did not reveal any advantage or disadvantage of prophylactic gastroenterostomy. Three prospective studies comparing prophylactic gastroenterostomy plus biliodigestive anastomosis with no bypass or a biliodigestive anastomosis alone were identified (altogether 218 patients). For patients who had prophylactic gastroenterostomy, the chance of gastric outlet obstruction during follow-up was significantly lower (odds ratio (OR) 0.06 (95 per cent confidence interval (c.i.) 0.02 to 0.21); P < 0.001). The rates of postoperative delayed gastric emptying were similar in both groups (OR 1.93 (95 per cent c.i. 0.57 to 6.53); P = 0.290), as were morbidity and mortality. The estimated duration of hospital stay after prophylactic gastroenterostomy was 3 days longer than for patients without bypass (weighted mean difference 3.1 (95 per cent c.i. 0.7 to 5.5); P = 0.010).

CONCLUSION

Prophylactic gastroenterostomy should be performed during surgical exploration of patients with unresectable pancreatic head tumours because it reduces the incidence of long-term gastroduodenal obstruction without impairing short-term outcome.

Weekly cetuximab (CET) plus oxaliplatin (OX), infusional 5-fluorouracil (5-FU) and radiation therapy (RT) as neoadjuvant treatment for esophageal squamous cell carcinoma (ESCC): A phase I study of the Arbeitsgemeinschaft Internistische Onkologie (AIO)

e15507

Background: CET, a chimeric monoclonal IgG1 antibody that targets the epidermal growth factor receptor (EGFR), has proven activity in a variety of SCC models in vitro and in vivo and has also been shown to enhance the activity of both chemo- and radiotherapy. Methods: Patients (pts) with locally advanced ESCC received CET for 2 weeks at an initial dose of 400mg/m2 (d - 15) i.v. followed by 250mg/m2(d -8) before they started a neoadjuvant dose escalation regimen. Pts received weekly CET 250mg/m2 plus RT 25 x 1.8 Gy (cumulative dose 45 Gy) d1–33. Cohort 1–3 received escalating doses of OX 45–50 mg/m2 d1,8,22,29 plus 5-FU 180–200–225 mg/m2/d; d1–5,8–12,15–19,22–26,29–33). Surgery was scheduled 4–6 weeks after RT. Toxicity was assessed according to NCI-CTC. Response was categorized according to the histopathologic score. Results: 15 pts were enrolled (2 female, 13 male; mean age 62 years, ECOG-PS 0 or 1). All pts had locally advanced SCC (uT2–4, cNx, cM0–1a) of the cervical (n=1), the upper (n=5) or the distal (n=7) esophagus. 6 pts were treated in cohort 1 and 3 pts in cohort 2 without any dose limiting toxicity (DLT). Of 6 pts treated in cohort 3, 1 pt developed grade 3 diarrhea and mucositis. All other observed toxicities were mild or moderate: anemia n=12, neutropenia n=2, thrombocytopenia n=3, nausea/vomiting n=8, mucositis n=6, diarrhea n=4, neuropathy n=4, hand-foot-syndrome n=8, skin rash n=14, no infection and no infusion-related reactions were observed. 12 pts underwent abdomino-thoracic esophagectomy with no postop. mortality; 3 pts were not resected. 8/12 resected pts had an R0 resection (67%) and 4 pts (33%) achieved a histopathological complete response (score 1a). Conclusions: 2 weeks of CET (400mg/m2 and 250mg/m2) followed by weekly CET (250mg/m2) plus OX 50mg/m2 d1,8,22,29, 5-FU 225 mg/m2/d d1–5,8–12,15–19,22–26,29–33 and RT 45 Gy (1.8Gy/f) was shown to be safe as neoadjuvant treatment for locally advanced ESCC. The anti-tumor activity of this regimen is promising and is being further investigated in an ongoing phase II study.

[Table: see text]

Defining new pancreatic tumour entities by molecular analysis

Recent advances in molecular biology, biochemistry and genetics have broadened our understanding of tumourigenesis and of the maintenance and spread of pancreatic cancer far beyond traditional microscopic histopathological analysis. While the main focus of pancreatic cancer research has been on pancreatic ductal adenocarcinoma, molecular research has also led to a better understanding of rare tumours of the pancreas, as well as to the definition of previously unknown tumour entities that can only be identified through the application of molecular tools. Furthermore, molecular analysis increasingly reveals the genetic and cell biological heterogeneity of established tumour entities, making subclassification of tumours possible. Genetic and molecular approaches may, therefore, not only lead to a better understanding of the pathogenesis of pancreatic tumours, but also culminate in more precise diagnosis as well as individually tailored treatment strategies for affected patients.

The "ELITE" model: construct validation of a new training system for natural orifice transluminal endoscopic surgery (NOTES)

BACKGROUND AND STUDY AIMS

The ELITE (endoscopic-laparoscopic interdisciplinary training entity) trainer is a new ex vivo model designed to train conventional laparoscopic and endoscopic skills and to perform hybrid interventions. The aim of the present study was to assess its usefulness for natural orifice transluminal endoscopic surgery (NOTES) procedures.

MATERIALS AND METHODS

A group of 30 participants (eight gastroenterologists, 22 surgeons) ranging from novices to experts completed the following tasks. Via a trans-sigmoidal approach, anchor points in each quadrant in the abdominal cavity had to be reached. Each participant performed five consecutive courses. The time needed to perform the experiment was evaluated. In a second step to assess advanced skill for NOTES in an external face validation, 20 randomly selected individuals performed a cholecystectomy via the same trans-sigmoidal access.

RESULTS

All participants passed a significant learning curve during the assessment (total time needed: 473.1 +/- 178.5 seconds for first pass vs. 321.9 +/- 182.0 seconds for fifth pass; P = 0.02, Wilcoxon test). There were 15 novices and 15 endoscopy experts. Significant differences were observed for the total time required to perform the respective procedures between these two groups (first pass: 394.3 +/- 176.6 seconds for experts vs. 531.9 +/- 166.7 seconds for novices; P = 0.040, Mann-Whitney test). Furthermore, NOTES cholecystectomies could successfully be simulated. Participants considered the ELITE to represent a useful simulator for NOTES.

CONCLUSION

The newly developed ELITE trainer is a suitable tool to train NOTES techniques. Experts could reliably be distinguished from novices and a significant progress by training could be demonstrated.

[Molecular mechanisms and its clinical impact in cancer cachexia]

Cachexia is a term used to describe the poor status of a patient suffering from a benign disease (Crohn's disease, chronic heart and kidney failure) as well as from a malignant disease. Cachexia has an important impact on the survival and morbidity in patients with cancer. The aim of this study is to elucidate the pathophysiology in cancer cachexia with a special emphasis on pancreatic cancer. The dramatic weight loss in malignant diseases is due to anorexia resulting in malnutrition and is characterised by a progressive loss of muscle and fat tissue. Different cytokines like TNF-alpha, IFN-gamma, IL-1, IL-6 are involved in this process. Via the ubiquitin-proteasome pathway, in which also the proteolysis inducing factor (PIF) is involved, the majority of protein is degraded. In patients with cancer cachexia we find an elevated level of lipases, which indicates that rather fat catabolism and not reduced fat synthesis is the main factor in fat metabolism. The development of an effective (pharmacological) treatment is still the main challenge. As yet, none of the used therapies show a long-lasting effect on weight stabilisation and survial. Cachexia is an important issue, especially in pancreatic cancer; it influences the qualitiy of life and has an important impact on survival. Today, there are only a few different pharmacological therapies used in the treatment of cancer cachexia, but each and every single treatment has failed to show a persistent effect on survival. The aim of research and treatment is to interrupt the natural clinical course of cachexia.

Expression of the CXCR6 on polymorphonuclear neutrophils in pancreatic carcinoma and in acute, localized bacterial infections

The chemokine receptor CXCR6 has been described on lymphoid cells and is thought to participate in the homing of activated T-cells to non-lymphoid tissue. We now provide evidence that the chemokine receptor CXCR6 is also expressed by activated polymorphonuclear neutrophils (PMN) in vivo: Examination of biopsies derived from patients with pancreatic carcinoma by confocal laser scan microscopy revealed a massive infiltration of PMN that expressed CXCR6, while PMN of the peripheral blood of these patients did not. To answer the question whether CXCR6 expression is a property of infiltrated and activated PMN, leucocytes were collected from patients with localized soft tissue infections in the course of the wound debridement. By cytofluorometry, the majority of these cells were identified as PMN. Up to 50% of these PMN were also positive for CXCR6. Again, PMN from the peripheral blood of these patients were nearly negative for CXCR6, as were PMN of healthy donors. In a series of in vitro experiments, up-regulation of CXCR6 on PMN of healthy donors by a variety of cytokines was tested. So far, a minor, although reproducible, effect of tumour necrosis factor (TNFalpha) was seen: brief exposure with low-dose TNFalpha induced expression of CXCR6 on the surface of PMN. Furthermore, we could show an increased migration of PMN induced by the axis CXCL16 and CXCR6. In summary, our data provide evidence that CXCR6 is not constitutively expressed on PMN, but is up-regulated under inflammatory conditions and mediates migration of CXCR6-positive PMN.

Clinical outcome and long-term survival in 118 consecutive patients with neuroendocrine tumours of the pancreas

BACKGROUND

The aim was to assess the clinical relevance of the World Health Organization and tumour node metastasis (TNM) classifications in patients with pancreatic neuroendocrine tumours (pNETs).

METHODS

Prospectively collected data from 118 consecutive patients with a pNET receiving surgical intervention were analysed.

RESULTS

Forty-one patients had well differentiated neuroendocrine tumours, 64 had well differentiated neuroendocrine carcinomas and 13 had poorly differentiated neuroendocrine carcinomas. Five-year survival rates were 95, 44 and 0 per cent respectively (P < 0.001). There was no difference in survival after R0 and R1/R2 resections in patients with neuroendocrine carcinomas (P = 0.905). In those with well differentiated neuroendocrine carcinomas, any resection and having a clinically non-functional tumour significantly increased survival (P = 0.003 and P = 0.037 respectively). The TNM stage was I in 37 patients, II in 15 patients, III in 32 patients and IV in 34 patients. There were significant differences in 5-year survival between stage I and II (88 and 85 per cent respectively) and stage III and IV (31 and 42 per cent respectively) (P = 0.010).

CONCLUSION

Both classifications accurately reflect the clinical outcome of patients with pNET. The resection status may not be critical for long-term survival in patients with pNET.

A new invasion score for determining the resectability of pancreatic carcinomas with contrast-enhanced multidetector computed tomography

OBJECTIVE

It was the aim of this study to evaluate a new infiltration score to determine the resectability of pancreatic carcinomas in preoperative planning.

MATERIALS AND METHODS

Eighty patients with suspected pancreatic tumor were examined prospectively using 16-row spiral CT. The scans were evaluated for the presence of pancreatic carcinoma, peripancreatic tumor extension and vascular invasion using a standardized questionnaire. Invasion of the surgically relevant vessels was evaluated using a new invasion score. The operative and histological findings and the clinical follow-up served as the gold standard.

RESULTS

Forty patients had a pancreatic carcinoma, 5 had metastasis of a different primary tumor, and in 35 patients, there was no malignant pancreatic disease. The sensitivity for tumor detection was 100%, with a specificity of 88% for differentiating between malignant and benign pancreatic tumors. Invasion of the surrounding vessels was evaluated correctly using the invasion score, with a sensitivity of 89% and a specificity of 99%. In evaluation of resectability, a sensitivity of 94% and a specificity of 89% were achieved.

CONCLUSION

Using 16-row spiral CT, the invasion score is a valid tool for correctly assessing invasion in relevant vessels in cases of pancreatic carcinoma and for determining resectability.

Long-term follow-up of a randomized clinical trial comparing Beger with pylorus-preserving Whipple procedure for chronic pancreatitis

BACKGROUND

Duodenum-preserving pancreatic head resection according to Beger and the pylorus-preserving Whipple (ppWhipple) procedure were compared in patients with chronic pancreatitis (CP) in a randomized clinical trial. Perioperative data and short-term outcome have been reported previously. The present study evaluated long-term follow-up.

METHODS

Forty patients were enrolled originally, 20 in each group. Long-term follow-up included mortality, morbidity, pain status, occupational rehabilitation, quality of life (QoL), and endocrine and exocrine function at median follow-up of 7 and 14 years.

RESULTS

One patient who had a ppWhipple procedure was lost to follow-up. There were five late deaths in each group. No differences were noted in pain status and exocrine pancreatic function. Loss of appetite was significantly worse in the ppWhipple group at 14 years' follow-up, but there were no other differences in QoL parameters examined. After 14 years, diabetes mellitus was present in seven of 15 patients who had the Beger procedure and 11 of 14 patients after ppWhipple resection (P = 0.128).

CONCLUSION

After long-term follow-up of up to 14 years early advantages of the Beger procedure were no longer present.

An audit of outcomes of a series of periampullary carcinomas

BACKGROUND

Non-pancreatic periampullary carcinoma such as ampullary carcinoma (AmpCA), distal cholangiocellular carcinoma (CholCA) and duodenal carcinoma (DuoCA) have a better prognosis than pancreatic head adenocarcinoma (PanCA). This study describes the outcome and parameters, which predict survival of non-pancreatic periampullary carcinoma after resection.

METHODS AND PATIENTS

Data from 148 consecutive patients with non-pancreatic periampullary carcinomas were recorded prospectively between 1993 and 2005 and analyzed using univariate and multivariate models.

RESULTS

One hundred thirty-three of 148 (90%) patients were resected for histologically proven non-pancreatic periampullary carcinomas. R0 resection was achieved for 92% of AmpCA, for 88% of CholCA and for all the DuoCA. The lowest recurrence rate was seen in DuoCA with 18%, followed by AmpCA with 21% and CholCA with 46%. The mean survival time was 60.9 months for AmpCA patients, 42.9 months for CholCA and 45.4 months for DuoCA patients. Five-year survival was 50.5%, 29.9% and 24.5% for AmpCA, CholCA and DuoCA, respectively. Multivariate analysis identified low bilirubin levels (<100 micromol/l), R0 resections and absence of surgical complications to be strong independent predictors of survival (p<0.05). In AmpCA low tumor stages are also an independent predictor of long-term survival (p<0.01). For T1/T2 AmpCA the 5-year survival rate was 61%, whereas none of the patients with a T3/T4 tumor survived 5 years.

CONCLUSION

Only T1/T2 ampullary carcinomas have a good prognosis, whereas T3/T4 ampullary tumors show aggressiveness similar to that of pancreatic head adenocarcinomas. Absence of surgical complications determines long-term outcome. Therefore, the combination of a complication-free and radical resection is essential for long-term survival.

[The effect of R1 resection in the hepatobiliary pancreatic system]

Macroscopic and microscopic complete resection, i.e. R0 resection, is a basic principle of oncologic hepatopancreatobiliary (HPB) surgery. The reported R1 rates for different HPB tumor entities vary considerably, most likely because of ambiguities in the exact definition of R1 resection and the lack of standardized histopathologic examination and reporting. R1 resections can be interpreted as technical/surgical failure (e.g. for small, peripherally located liver tumors). In most cases, however, R1 resections are determined by the anatomic location of the tumor and the growth pattern (e.g. pancreatic cancer with perineural invasion). R0 resections have been identified as positive predictive markers for several HPB tumors (in comparison to R1 resection). Therefore HPB surgeons should always aim at macroscopic and microscopic complete resections. Nonetheless, R1 resections often provide an advantage over no resection with respect to survival and quality of life in patients with these tumors.

Improved lentiviral transduction of human mesenchymal stem cells for therapeutic intervention in pancreatic cancer

Genetic modification of human bone marrow mesenchymal stem cells (MSC) is highly valuable for their exploitation in basic science and therapeutic applications, for example in cancer. We present here a new, fast and easy-to-use method to enrich a functional population of lentiviral (LV)-transduced MSC expressing enhanced green fluorescent protein (eGFP). We replaced the eGFP gene by a fusion gene of puromycin acetyltransferase and eGFP. Upon LV gene transfer and puromycin selection, we quickly obtained a pure transduced MSC population, in which growth, differentiation capacity and migration preferences were not compromised. Furthermore, we are the first to report the migration velocity of MSC among which 30% were moving and velocity of about 15 mum h(-1) was not altered by LV transduction. Manipulated MSC underwent senescence one passage earlier than non-transduced cells, suggesting the use for therapeutic intervention in early passage numbers. Upon tail vein application in nude mice, the majority of LV-transduced MSC could be detected in human orthotopic pancreatic tumor xenografts and to a minor extent in mouse liver, kidney and lung. Together, LV transduction of genes to MSC followed by puromycin selection is a powerful tool for basic research and improves the therapeutic prospects of MSC as vehicles in gene therapy.