Interplay of tumor microenvironment cell types with parenchymal cells in pancreatic cancer development and therapeutic implications

Distinct Response of Circulating microRNAs to the Treatment of Pancreatic Cancer Xenografts with FGFR and ALK Kinase Inhibitors

Pancreatic adenocarcinoma is typically detected at a late stage and thus shows only limited sensitivity to treatment, making it one of the deadliest malignancies. In this study, we evaluate changes in microRNA (miR) patterns in peripheral blood as a potential readout of treatment responses of pancreatic cancer to inhibitors that target tumor-stroma interactions. Mice with pancreatic cancer cell (COLO357PL) xenografts were treated with inhibitors of either fibroblast growth factor receptor kinase (FGFR; PD173074) or anaplastic lymphoma kinase receptor (ALK; TAE684). While both treatments inhibited tumor angiogenesis, signal transduction, and mitogenesis to a similar extent, they resulted in distinct changes in circulating miR signatures. Comparison of the miR pattern in the tumor versus that in circulation showed that the inhibitors can be distinguished by their differential impact on tumor-derived miRs as well as host-derived circulating miRs. Distinct signatures that include circulating miR-1 and miR-22 are associated with the efficacy of ALK and FGFR inhibition, respectively. We propose that monitoring changes in circulating miR profiles can provide an early signature of treatment response or resistance to pathway-targeted drugs, and thus provide a non-invasive measurement to rapidly assess the efficacy of candidate therapies.

Irreversible electroporation and the pancreas: What we know and where we are going?

Pancreatic adenocarcinoma continues to have a poor prognosis with 1 and 5 years survival rates of 27% and 6% respectively. The gold standard of treatment is resection, however, only approximately 10% of patients present with resectable disease. Approximately 40% of patients present with disease that is too locally advanced to resect. There is great interest in improving outcomes in this patient population and ablation techniques have been investigated as a potential solution. Unfortunately early investigations into thermal ablation techniques, particularly radiofrequency ablation, resulted in unacceptably high morbidity rates. Irreversible electroporation (IRE) has been introduced and is promising as it does not rely on thermal energy and has shown an ability to leave structural cells such as blood vessels and bile ducts intact during animal studies. IRE also does not suffer from heat sink effect, a concern given the large number of blood vessels surrounding the pancreas. IRE showed significant promise during preclinical animal trials and as such has moved on to clinical testing. There are as of yet only a few studies which look at the applications of IRE within humans in the setting of pancreatic adenocarcinoma. This paper reviews the basic principles, techniques, and current clinical data available on IRE.

Apoptosis and anergy of T cell induced by pancreatic stellate cells-derived galectin-1 in pancreatic cancer

Galectin-1, a β-galactoside-binding protein implicated in cancer cell immune privilege, was highly expressed in activated pancreatic stellate cells (PSCs). This study was designed to investigate the relationship between PSC-derived galectin-1 and tumor immunity in pancreatic cancer. Isolated PSCs were identified as normal pancreas cells (hNPSCs) or pancreatic cancer cells (hCaPSCs) by immunohistochemical staining for α-SMA and vimentin, and galectin-1 expression was evaluated by Western blotting and quantitative RT-PCR. Apoptosis, caspase activity, and cytokine production (IL-6, IL-10, TNF-β, and IFN-γ) of T cells co-cultured with PSCs were evaluated, and immunohistochemical staining of galectin-1 was correlated with CD3 and clinicopathological variables in 66 pancreatic cancer and 10 normal pancreatic tissue samples. hCaPSCs exhibited higher galectin-1 expression than did hNPSCs, and hCaPSCs induced higher levels of apoptosis in T cells following co-culture. hCaPSCs activated caspase-9 and caspase-3 in the mitochondrial apoptotic pathway and stimulated secretion of Th2 cytokines (IL-6 and IL-10) but decreased secretion of Th1 cytokines (TNF-β and IFN-γ), compared with hNPSCs. Immunohistochemical staining indicated that galectin-1 and CD3 were more highly expressed in pancreatic cancer tissue. Galectin-1 expression was highest in poorly differentiated pancreatic cancer cells and lowest in well-differentiated pancreatic cancer cells and was associated with tumor size, lymph node metastasis, differentiation, and UICC stage. However, CD3 expression showed the opposite trend and was highest in well-differentiated pancreatic cancer cells and was associated with tumor differentiation and UICC stage. High expression of galectin-1 was associated with short survival, as was low expression of CD3. hCaPSC-derived galectin-1 enhanced apoptosis and anergy of T cells in pancreatic cancer, which contributes to the immune escape of pancreatic cancer cells.

The role of pancreatic stellate cells in pancreatic cancer

BACKGROUND

The prognosis of pancreatic cancer remains desperately poor, with little progress made over the past 30 years despite the development of new combination chemotherapy regimens. Stromal activity is especially prominent in the tissue surrounding pancreatic tumours, and has a profound influence in dictating tumour development and dissemination. Pancreatic stellate cells (PaSCs) have a key role in this tumour microenvironment, and have been the subject of much research in the past decade. This review examines the relationship between PaSCs and cancer cells.

METHODS

A comprehensive literature search was performed of multiple databases up to March 2014, including Medline, Pubmed and Google Scholar.

RESULTS

A complex bidirectional interplay exists between PaSCs and cancer cells, resulting in a perpetuating loop of increased activity and an overriding pro-tumorigenic effect. This involves a number of signalling pathways that also impacts on other stromal components and vasculature, contributing to chemoresistance. The Reverse Warburg Effect is also introduced as a novel concept in tumour stroma.

CONCLUSION

This review highlights the pancreatic tumour microenvironment, and in particular PaSCs, as an ideal target for therapeutics. There are a number of cellular processes involving PaSCs which could hold the key to more effectively treating pancreatic cancer. The feasibility of targeting these pathways warrant further in depth investigation, with the aim of reducing the aggressiveness of pancreatic cancer and improving chemodelivery.

Human Pancreatic Cancer-Associated Stellate Cells Remain Activated after in vivo Chemoradiation

Pancreatic ductal adenocarcinoma (PDAC) is characterized by an extensive fibrotic reaction or desmoplasia and complex involvement of the surrounding tumor microenvironment. Pancreatic stellate cells are a key mediator of the pancreatic matrix and they promote progression and invasion of pancreatic cancer by increasing cell proliferation and offering protection against therapeutic interventions. Our study utilizes human tumor-derived pancreatic stellate cells (HTPSCs) isolated from fine needle aspirates of pancreatic cancer tissue from patients with locally advanced, unresectable pancreatic adenocarcinoma before and after treatment with full-dose gemcitabine plus concurrent hypo-fractionated stereotactic radiosurgery. We show that HTPSCs survive in vivo chemotherapy and radiotherapy treatment and display a more activated phenotype post-therapy. These data support the idea that stellate cells play an essential role in supporting and promoting pancreatic cancer and further research is needed to develop novel treatments targeting the pancreatic tumor microenvironment.

Necrotizing fasciitis in three university hospitals in Korea: a change in causative microorganisms and risk factors of mortality during the last decade

Background

Necrotizing fasciitis is a life-threatening infectious disease with rapidly progressive involvement of the affected site. Because of the high mortality rate of this disease, early diagnosis, surgical exploration, and administration of appropriate antibiotics are necessary. The present study aimed to further review the changes in the clinical and microbiological characteristics of necrotizing fasciitis using patients' medical records from consecutive databases of 3 hospitals in Korea.

Materials and Methods

In this study, we retrospectively reviewed the medical records of patients with necrotizing fasciitis who were clinically diagnosed between May 2001 and February 2012 in 3 university hospitals in Korea. In total, the data of 83 patients were analyzed, including those of 20 patients from our previous study in 2006. An organism found in a blood culture or surgical specimen was regarded as a causative organism.

Results

Of the 83 patients, 68(81.9%) had community-acquired infections. Ninety microorganism species were indentifed by culture. Streptococcus was the most commonly identified pathogen. Non-fermentative gram-negative bacteria and Candida species have recently emerged, especially in immunocompromised hosts.

Conclusions

Gram-positive organisms are still the most common pathogens of necrotizing fasciitis. However in our study, various gram-negative bacteria with different levels of susceptibility to antibiotics, as well as Candida species, were responsible for the necrotizing fasciitis. Initial empirical antimicrobial agents for necrotizing fasciitis should be considered depending on the individual patient's condition.

How fibrosis influences imaging and surgical decisions in pancreatic cancer

Our understanding of pancreatic ductal adenocarcinoma (PDAC) is shifting away from a disease of malignant ductal cells-only, toward a complex system where tumor evolution is a result of interaction of cancer cells with their microenvironment. This change has led to intensification of research focusing on the fibrotic stroma of PDAC. Pancreatic stellate cells (PSCs) are the main fibroblastic cells of the pancreas which are responsible for producing the desmoplasia in chronic pancreatitis (CP) and PDAC. Clinically, the effect of desmoplasia is two-sided; on the negative side it is a hurdle in the diagnosis of PDAC because the fibrosis in cancer resembles that of CP. It is also believed that PSCs and pancreatic fibrosis are partially responsible for the therapy resistance in pancreatic cancer. On the positive side, a fibrotic pancreas is safer to operate on compared to a fatty and soft pancreas which is prone for postoperative pancreatic fistula. In this review the impact of pancreatic fibrosis on diagnosis of pancreatic cancer and surgical decisions are discussed from a clinical point of view.

Mucin-based targeted pancreatic cancer therapy

The prognosis of pancreatic cancer (PC) patients is very poor with a five-year survival of less than 5%. One of the major challenges in developing new therapies for PC is the lack of expression of specific markers by pancreatic tumor cells. Mucins are heavily Oglycosylated proteins characterized by the presence of short stretches of amino acid sequences repeated several times in tandem. The expression of several mucins including MUC1, MUC4, MUC5AC, and MUC16 is strongly upregulated in PC. Recent studies have also demonstrated a link between the aberrant expression and differential overexpression of mucin glycoproteins to the initiation, progression, and poor prognosis of the disease. These studies have led to increasing recognition of mucins as potential diagnostic markers and therapeutic targets in PC. In this focused review we present an overview of the therapies targeting mucins in PC, including immunotherapy (i.e. vaccines, antibodies, and radioimmunoconjugates), gene therapy, and other novel therapeutic strategies.

The role of stroma in pancreatic cancer: diagnostic and therapeutic implications

Pancreatic ductal adenocarcinoma (PDAC) is one of the five most lethal malignancies worldwide and survival has not improved substantially in the past 30 years. Desmoplasia (abundant fibrotic stroma) is a typical feature of PDAC in humans, and stromal activation commonly starts around precancerous lesions. It is becoming clear that this stromal tissue is not a bystander in disease progression. Cancer-stroma interactions effect tumorigenesis, angiogenesis, therapy resistance and possibly the metastatic spread of tumour cells. Therefore, targeting the tumour stroma, in combination with chemotherapy, is a promising new option for the treatment of PDAC. In this Review, we focus on four issues. First, how can stromal activity be used to detect early steps of pancreatic carcinogenesis? Second, what is the effect of perpetual pancreatic stellate cell activity on angiogenesis and tissue perfusion? Third, what are the (experimental) antifibrotic therapy options in PDAC? Fourth, what lessons can be learned from Langton's Ant (a simple mathematical model) regarding the unpredictability of genetically engineered mouse models?

Self-expanding metal stents for biliary drainage in patients with resectable pancreatic cancer: single-center experience with 79 cases

BACKGROUND AND AIMS

To study pre-operative and peri-operative course and outcome on follow up after pancreaticoduodenenctomy (PD) for resectable pancreatic cancer amongst patients receiving self-expanding metal stents (SEMS).

METHODS

Medical charts of consecutively reviewed patients (2005-2009) with resectable pancreatic cancer and SEMS placement before PD at the MD Anderson Cancer Center (MDACC) were studied.

RESULTS

Seventy-nine patients (mean age, 68 ± 9 years; 54% males) undergoing PD after SEMS placement were analyzed. Of these, 70% (55/79) had come with previous plastic stents placed within a median of 29 (5-216) days because of presentation and most (95%) underwent neoadjuvant chemoradiation after SEMS placement. The median interval between SEMS placement and PD was 120 (range 28-306) days. There were no technical difficulties during PD. The resected tumor was stage T3 in 72 patients, positive node in 44, lymphovascular invasion in 47, and perineural invasion in 62. Within 30 days after surgery, 26 (33%) patients developed complications requiring intervention, but none died. During a median follow-up of 349 (14-1,508) days after surgery, 32 (41%) patients developed metastatic disease, and 20 (25%) died; median survival was approximately 3 years. Development of metastatic disease during follow-up independently predicted survival with hazard ratio of 16 (95% CI: 4-68; P = 0.0001).

CONCLUSIONS

Contrary to the tendency of avoiding the use of metal stents for biliary decompression amongst patients with resectable pancreatic cancer, our study demonstrated that SEMS did not adversely affect surgical technique, postoperative course, or long-term outcome. Therefore, metal stents should be considered for patients with resectable pancreatic cancer who will undergo preoperative chemoradiation.

A Cancer and Leukemia Group B phase II study of sunitinib malate in patients with previously treated metastatic pancreatic adenocarcinoma (CALGB 80603)

BACKGROUND

The Cancer and Leukemia Group B (CALGB) conducted a phase II study evaluating sunitinib in patients with progressive metastatic pancreas adenocarcinoma following prior gemcitabine-based therapy (trial CALGB 80603; ClinicalTrials.gov identifier, NCT00397787). The primary endpoint was to determine the disease control rate (DCR) as measured by the Response Evaluation Criteria in Solid Tumors (complete response, partial response [PR], and stable disease) at 6 weeks.

PATIENTS AND METHODS

Patients aged ≥18 years with an Eastern Cooperative Oncology Group (ECOG) performance status score of 0-2 and with progressive pancreas adenocarcinoma following treatment with gemcitabine were eligible. Sunitinib was dosed at 50 mg orally days 1-28, every 42 days (1 cycle). The statistical plan called for a three-stage design. A DCR ≥15% was considered worthy of further study.

RESULTS

In total, 77 patients were enrolled. Forty-two (54.6%) enrollees were male. The median age was 65 years. The ECOG performance status score distribution was: 0, 39%; 1, 50%; 2, 11%. The DCR was 21.6%; one patient (1.4%) had a PR and 15 patients (20.3%) had stable disease as their best response. The progression-free survival time was 1.31 months (95% confidence interval [CI] 1.25-1.38 months) and overall survival time was 3.68 months (95% CI, 3.06-4.24 months).

CONCLUSIONS

The study met its primary endpoint; however sunitinib had minimal activity and moderate toxicity in a population of gemcitabine-refractory pancreas adenocarcinoma patients. For future studies, limiting enrollment to patients with an ECOG performance status score of 0-1 is recommended.

Interplay of tumor microenvironment cell types with parenchymal cells in pancreatic cancer development and therapeutic implications

INTRODUCTION

The process of "induction," namely, the formation of a tissue by the functional interaction between the epithelial layer and the stroma, is key for the development of many organs, in particular to the pancreas.

DISCUSSION

In diseases like pancreatic cancer, most studies performed to date, in the area of pancreatic cancer, have focused on studying epithelial cells and their contribution to this disease. Strikingly, until recently, the stroma that surrounds cancer cells in pancreatic tumors (desmoplastic reaction-tumor microenvironment) has remained an underrepresented area of research. However, several laboratories are increasingly posing questions as what is the role of this tumor microenvironment in the development and progression of this fatal disease. Therefore, in the current article, we define and describe the components of this desmoplastic reaction and the pancreatic tumor microenvironment and briefly review advances being made. More importantly, we highlight the urgent need of research in this field.

CONCLUSION

We anticipate that, because of the paucity of knowledge on this subject, studies on the pancreatic tumor microenvironment will bring new concepts which will ultimately impact in designing new diagnosis and treatment for this disease.