Novel agents for the treatment of adenocarcinoma of the pancreas

Development of detection method for novel fusion gene using GeneChip exon array

Background

Fusion genes have been recognized to play key roles in oncogenesis. Though, many techniques have been developed for genome-wide analysis of fusion genes, a more efficient method is desired.

Results

We introduced a new method of detecting the novel fusion gene by using GeneChip Exon Array that enables exon expression analysis on a whole-genome scale and TAIL-PCR. To screen genes with abnormal exon expression profiles, we developed computational program, and confirmed that the program was able to search the fusion partner gene using Exon Array data of T-cell acute lymphocytic leukemia (T-ALL) cell lines. It was reported that the T-ALL cell lines, ALL-SIL, BE13 and LOUCY, harbored the fusion gene NUP214-ABL1, NUP214-ABL1 and SET-NUP214, respectively. The program extracted the candidate genes with abnormal exon expression profiles: 1 gene in ALL-SIL, 1 gene in BE13, and 2 genes in LOUCY. The known fusion partner gene NUP214 was included in the genes in ALL-SIL and LOUCY. Thus, we applied the proposed program to the detection of fusion partner genes in other tumors. To discover novel fusion genes, we examined 24 breast cancer cell lines and 20 pancreatic cancer cell lines by using the program. As a result, 20 and 23 candidate genes were obtained for the breast and pancreatic cancer cell lines respectively, and seven genes were selected as the final candidate gene based on information of the EST data base, comparison with normal cell samples and visual inspection of Exon expression profile. Finding of fusion partners for the final candidate genes was tried by TAIL-PCR, and three novel fusion genes were identified.

Conclusions

The usefulness of our detection method was confirmed. Using this method for more samples, it is thought that fusion genes can be identified.

Decreased TIP30 expression predicts poor prognosis in pancreatic cancer patients

Pancreatic ductal adenocarcinoma (PDAC) is known for its aggressive growth, and is characterized by early tissue invasion and metastasis with poor prognosis. Identifying prognostic markers and delineating the underlying mechanisms that promote progression of PDAC are important for the treatment of pancreatic cancer. TIP30, a newly identified tumor suppressor, appears to be involved in multiple processes during tumor development and metastasis. Here, we investigated the expression of TIP30 in PDAC and its prognostic value in PDAC patients. We examined the expression of TIP30 by immunohistochemistry in tissue microarrays containing 106 surgically resected PDAC. Kaplan-Meier analysis and Cox proportional hazards regression modeling analysis showed that TIP30 expression independently predicted better survival in pancreatectomy patients (p < 0.01). Moreover, decreased TIP30 expression was associated with lymph node metastasis (p < 0.05) and loss of E-cadherin expression (r = 0.329, p < 0.01). Suppression of TIP30 resulted in upregulation of Snail and subsequent downregulation of E-cadherin in SW1990 cells containing high-level of endogenous TIP30. However, in the PANC-1 cells containing low level of endogenous TIP30, suppressing TIP30 caused upregulation of Slug instead of Snail, followed by upregulation of MMP9 rather than E-cadherin. Taken together, our work reveals that decreased TIP30 expression is able to enhance invasion and metastasis of pancreatic cancer cells through upregulation of the Snail family members and may serve as an independent predictor for poor outcomes in PDAC patients.

Role of α-gal epitope/anti-Gal antibody reaction in immunotherapy and its clinical application in pancreatic cancer

Pancreatic cancer is one of the most common causes of death from cancer. Despite the availability of various treatment modalities, such as surgery, chemotherapy and radiotherapy, the 5-year survival remains poor. Although gemcitabine-based chemotherapy is typically offered as the standard care, most patients do not survive longer than 6 months. Therefore, new therapeutic approaches are needed. The α-gal epitope (Galα1-3Galβ1-4GlcNAc-R) is abundantly synthesized from glycoproteins and glycolipids in non-primate mammals and New World monkeys, but is absent in humans, apes and Old World monkeys. Instead, they produce anti-Gal antibody (Ab) (forming approximately 1% of circulating immunoglobulins), which specifically interacts with α-gal epitopes. Anti-Gal Ab can be exploited in cancer immunotherapy as vaccines that target antigen-presenting cells (APC) to increase their immunogenicity. Tumor cells or tumor cell membranes from pancreatic cancer are processed to express α-gal epitopes. Subsequent vaccination with such processed cell membranes results in in vivo opsonization by anti-Gal IgG in cancer patients. The interaction of the Fc portion of the vaccine-bound anti-Gal with Fcγ receptors of APC induces effective uptake of the vaccinating tumor cell membranes by the APC, followed by effective transport of the vaccinating tumor membranes to the regional lymph nodes, and processing and presentation of the tumor-associated antigens. Activation of tumor-specific B and T cells could elicit an immune response that in some patients is potent enough to eradicate the residual cancer cells that remain after completion of standard therapy. This review addresses these topics and new avenues of clinical importance related to this unique antigen/antibody system (α-gal epitope/anti-Gal Ab) and advances in immunotherapy in pancreatic cancer.

ATF2, a novel factor promoting epithelial-mesenchymal transition in human pancreatic cancer cells

AIM: To investigate whether ATF2 together with TGF-β1 can induce epithelial-mesenchymal transition (EMT) in human pancreatic cancer cell line Capan2.

METHODS: Capan2 cells were induced with TGF-β1 after transfection with PGEX-ATF2, and the negative control group was treated with DMSO. Cell morphological alternations were examined by phase contrast microscopy. The expression of mesenchymal marker vimentin and epithelial markers E-cadherin and ATF2 were detected by Western blot. Cell migration was determined by Transwell motility assay.

RESULTS: Compare to the negative control group, cells transfected with ATF2 and treated with TGF-β1 showed loss of cell-cell contacts, fibroblastic morphology, decreased expression of E-cadherin, up-regulated expression of vimentin and ATF2, and increased migration ability (P = 0.008).

CONCLUSION: ATF2 together with TGF-β1 can induce EMT in human pancreatic cancer cell line Capan2. ATF2 may be a new molecular target for therapy of pancreatic cancer.

Myxoma virus sensitizes cancer cells to gemcitabine and is an effective oncolytic virotherapeutic in models of disseminated pancreatic cancer

Myxoma virus (MYXV) is a novel oncolytic virus that has been shown to replicate in pancreatic cancer cells, but its efficacy in animal models of pancreatic cancer has not been determined. The efficacy of MYXV as monotherapy or in combination with gemcitabine was evaluated in intraperitoneal dissemination (IPD) models of pancreatic cancer. The effects of an intact immune system on the efficacy of MYXV therapy was tested by comparing immunodeficient versus immunocompetent murine models and combination therapy with gemcitabine was also evaluated. In cell culture, MYXV replication was robust in a broad range of pancreatic cancer cells and also showed increased oncolysis in combination with gemcitabine. In animal models, MYXV treatment conferred survival benefits over control or gemcitabine-treated cohorts regardless of the cell line or animal model used. MYXV monotherapy was most effective in an immunocompetent IPD model, and resulted in 60% long-term survivors. In Pan02 engrafted immunocompetent IPD models, sequential treatment in which MYXV was administered first, followed by gemcitabine, was the most effective and resulted in 100% long-term survivors. MYXV is an effective oncolytic virus for pancreatic cancer and can be combined with gemcitabine to enhance survival, particularly in the presence of an intact host immune system.

2-Triazenoazaindoles: α novel class of triazenes inducing transcriptional down-regulation of EGFR and HER-2 in human pancreatic cancer cells

Pancreatic cancer is a complex malignancy arising from the accumulation of genetic and epigenetic defects in the affected cells. Standard chemotherapy for patients with advanced disease shows only modest effects and is associated with considerable toxicity. Overexpression or aberrant activation of members of the epidermal growth factor receptor tyrosine kinase family, which includes EGFR and HER-2, occurs frequently and is associated with multiple drug resistance and decreased patient survival. In this study, we have investigated the therapeutic potential of AS104, a novel compound of the triazene class, with potential inhibitory effects on EGFR. We found that treatment of cells with AS104 causes significant reduction of cell growth and metabolic activity in four human pancreatic cancer cell lines. Furthermore, we show that the AS104-mediated induction of apoptotic cell death is associated with stimulation of autophagy in a dose-dependent manner. Treatment of cells with AS104 results in significant down-regulation of EGFR and HER-2 expression and activity and subsequent inhibition of downstream signaling proteins. Quantitative RT-PCR analysis and assays with proteasome inhibitors revealed that AS104 regulates the expression of EGFR and HER-2 at the transcriptional level. These findings provide for the first time experimental evidence for efficacy of AS104 in the simultaneous transcriptional repression of EGFR and HER-2 genes and suggest that AS104 may have therapeutic potential in the treatment of pancreatic cancers that express high levels of the aforementioned receptor tyrosine kinases.

A recombinant decoy comprising EGFR and ErbB-4 inhibits tumor growth and metastasis

EGF-like growth factors control tumor progression, as well as evasion from the toxic effects of chemotherapy. Accordingly, antibodies targeting the cognate receptors, such as EGFR/ErbB-1 and the co-receptor HER2/ErbB-2, are widely used to treat cancer patients, but agents that target the EGF-like growth factors are not available. To circumvent the existence of 11 distinct ErbB ligands, we constructed a soluble fusion protein (hereinafter: TRAP-Fc) comprising truncated extracellular domains of EGFR/ErbB-1 and ErbB-4. The recombinant TRAP-Fc retained high affinity ligand binding to EGF-like growth factors and partially inhibited growth of a variety of cultured tumor cells. Consistently, TRAP-Fc displayed an inhibitory effect in xenograft models of human cancer, as well as synergy with chemotherapy. Additionally, TRAP-Fc inhibited invasive growth of mammary tumor cells and reduced their metastatic seeding in the lungs of animals. Taken together, the activities displayed by TRAP-Fc reinforce critical roles of EGF-like growth factors in tumor progression, and they warrant further tests of TRAP-Fc in pre-clinical models.

JDP2 suppresses transforming growth factor-β1-induced epithelial-mesenchymal transition in human pancreatic cancer cell line Panc-1

AIM: To determine the correlation between overexpression of Jun dimerization protein 2 (JDP2) and epithelial-mesenchymal transition (EMT) in human pancreatic cancer cell line Panc-1.

METHODS: Panc-1 cells were divided into three groups: negative control group, JDP2-transfected group, and empty vector-transfected group. The JDP2-transfected group and empty vector-transfected group were transiently transfected with PCEFL-HA-JDP2 vector and pCEFL vector, respectively. Untreated Panc-1 cells were used as normal controls. Forty-eight hours after transfection, cells were treated with TGF-β1 (10 ng/mL). Cell morphological alternations were examined by phase-contrast microscopy. The expression of mesenchymal marker vimentin and epithelial marker E-cadherin was detected by RT-PCR and Western blot. Cell migration was determined by Transwell motility assay.

RESULTS: TGF-β1-induced EMT was inhibited in the JDP2-transfected group. Compare to the negative control group, cells in the JDP2-transfected group showed no fibroblastic morphology and no significant changes in the levels of E-cadherin and vimentin and in migration ability (48.0 ± 5.3 vs 52.0 ± 7.2). However, cells in the vector-transfected group showed loss of cell-cell contacts, fibroblastic morphology, decreased expression of E-cadherin (mRNA: P < 0.01; protein: P < 0.05), increased expression of vimentin (P < 0.01) and migration ability (48.0 ± 5.3 vs 81.0 ± 10.7, P < 0.01) when compared to the negative control group.

CONCLUSION: JDP2 can inhibit TGF-β1-induced EMT in Panc-1 cells and may be a molecular target for pancreatic carcinoma therapy.

Management of pancreatic cancer: current status and future directions

Pancreatic ductal adenocarcinoma has a dismal prognosis, despite advances in surgery, and adjuvant therapy. Surgical resection with negative margins remains the mainstay of treatment, and results can be improved with neoadjuvant therapy when the lesion is of borderline respectability. Extended lymphadenectomy has no role in improving survival, but may worsen quality of life. Venous resection can be performed if it helps to achieve an R0 resection, but arterial resection is not justified. A host of newer agents, both cytotoxic and targeted, are being evaluated. The article summarizes the critical issues and looks ahead to the future.

Potential targets for pancreatic cancer immunotherapeutics

Pancreatic adenocarcinoma is the fourth leading cause of cancer death with an overall 5-year survival of less than 5%. As there is ample evidence that pancreatic adenocarcinomas elicit antitumor immune responses, identification of pancreatic cancer-associated antigens has spurred the development of vaccination-based strategies for treatment. While promising results have been observed in animal tumor models, most clinical studies have found only limited success. As most trials were performed in patients with advanced pancreatic cancer, the contribution of immune suppressor mechanisms should be taken into account. In this article, we detail recent work in tumor antigen vaccination and the recently identified mechanisms of immune suppression in pancreatic cancer. We offer our perspective on how to increase the clinical efficacy of vaccines for pancreatic cancer.

Myeloid-derived suppressor cells: general characteristics and relevance to clinical management of pancreatic cancer

Recent studies describe a heterogeneous population of cells of the myeloid lineage, termed myeloid derived suppressor cells (MDSC), which are observed with increased prevalence in the peripheral blood and tumor microenvironment of cancer patients, including pancreatic cancer. Accumulation of MDSC in the peripheral circulation has been related to extent of disease, and correlates with stage. MDSC have primarily been implicated in promoting tumor growth by suppressing antitumor immunity. There is also compelling evidence MDSC are also involved in angiogenesis and metastatic spread. Two main subsets of MDSC have been identified in cancer patients: a monocytic subset, characterized by expression of CD14, and a granulocytic subset characterized by expression of CD15. Both subsets of MDSC actively suppress host immunity through a variety of mechanisms including production of reactive oxygen species and arginase. Just as in humans, accumulation of monocytic and granulocytic MDSC has been noted in the bone marrow, spleen, peripheral circulation, and tumors of tumor bearing mice. Successful targeting of MDSC in mice is associated with improved immune responses, delayed tumor growth, improved survival, and increased efficacy of vaccine therapy. By further elucidating mechanisms of MDSC recruitment and maintenance in the tumor environment, strategies could be developed to reverse immune tolerance to tumor. We discuss here what is currently known about MDSC as well as some potential strategies targeting MDSC in the context of our work on pancreatic cancer and recent literature. Due to the number of new reports on MDSC, the most pertinent ones have been selected.

Oncolytic virotherapy for pancreatic cancer

Within the past decade, many oncolytic viruses (OVs) have been studied as potential treatments for pancreatic cancer and some of these are currently under clinical trials. The applicability of certain OVs, such as adenoviruses, herpesviruses and reoviruses, for the treatment of pancreatic cancer has been intensively studied for several years, whereas the applicability of other more recently investigated OVs, such as poxviruses and parvoviruses, is only starting to be determined. At the same time, studies have identified key characteristics of pancreatic cancer biology that provide a better understanding of the important factors or pathways involved in this disease. This review aims to summarise the different replication-competent OVs proposed as therapeutics for pancreatic cancer. It also focuses on the unique biology of these viruses that makes them exciting candidate virotherapies for pancreatic cancer and discusses how they could be genetically manipulated or combined with other drugs to improve their efficacy based on what is currently known about the molecular biology of pancreatic cancer.

Tyrosine 23 phosphorylation-dependent cell-surface localization of annexin A2 is required for invasion and metastases of pancreatic cancer

The aggressiveness of pancreatic ductal adenocarcinoma (PDA) is characterized by its high metastatic potential and lack of effective therapies, which is the result of a lack of understanding of the mechanisms involved in promoting PDA metastases. We identified Annexin A2 (ANXA2), a member of the Annexin family of calcium-dependent phospholipid binding proteins, as a new molecule that promotes PDA invasion and metastases. We found ANXA2 to be a PDA-associated antigen recognized by post-treatment sera of patients who demonstrated prolonged survival following treatment with a PDA-specific vaccine. Cell surface ANXA2 increases with PDA development and progression. Knockdown of ANXA2 expression by RNA interference or blocking with anti-ANXA2 antibodies inhibits in vitro invasion of PDA cells. In addition, post-vaccination patient sera inhibits in vitro invasion of PDA cells, suggesting that therapeutic anti-ANXA2 antibodies are induced by the vaccine. Furthermore, cell-surface localization of ANXA2 is tyrosine 23 phosphorylation-dependent; and tyrosine 23 phosphorylation is required for PDA invasion. We demonstrated that tyrosine 23 phosphorylation resulting in surface expression of ANXA2 is required for TGFβ-induced, Rho-mediated epithelial-mesenchymal transition (EMT), linking the cellular function of ANXA2 which was previously shown to be associated with small GTPase-regulated cytoskeletal rearrangements, to the EMT process in PDA. Finally, using mouse PDA models, we showed that shRNA knock-down of ANXA2, a mutation at tyrosine 23, or anti-ANXA2 antibodies, inhibit PDA metastases and prolong mouse survival. Thus, ANXA2 is part of a novel molecular pathway underlying PDA metastases and a new target for development of PDA therapeutics.

Slug enhances invasion ability of pancreatic cancer cells through upregulation of matrix metalloproteinase-9 and actin cytoskeleton remodeling

Slug, a member of the Snail family of transcription factors, has a crucial role in the regulation of epithelial-mesenchymal transition (EMT) by suppressing several epithelial markers and adhesion molecules, including E-cadherin. A recent study demonstrated that no relationship exists between Slug and E-cadherin in pancreatic cancer. Another study showed that in malignant mesothelioma effusions Slug was associated with matrix metalloproteinase (MMP) expression, but that there was no association with E-cadherin. F-ascin is an actin-bundling protein involved in filopodia assembly and cancer invasion and metastasis of multiple epithelial cancer types. In this study, we investigated Slug, E-cadherin, and MMP-9 expression using immunohistochemistry in 60 patients with pancreatic cancer and their correlation with carcinoma invasion and metastasis. Additionally, we observed the effects of Slug on invasion and metastasis in the pancreatic cancer cell line PANC-1. Alterations in Slug, MMP-9, and E-cadherin were determined by RT-PCR, western blot, and immunohistochemistry. Alterations in MMP-9 and F-actin cytoskeleton were determined by immunofluorescence staining, flow cytometry (FCM), or gelatin zymography. Slug, E-cadherin, and MMP-9 expression in pancreatic cancer was significantly associated with lymph node metastases and we found a significant correlation between Slug and MMP-9 expression; however, no significant correlation was observed between Slug and E-cadherin expression. Slug transfection significantly increased invasion and metastasis in PANC-1 cells and orthotopic tumor of mouse in vivo, and significantly upregulated and activated MMP-9; however, there was no effect on E-cadherin expression. Slug promoted the formation of lamelliopodia or filopodia in PANC-1 cells. The intracellular F-actin and MMP-9 was increased and relocated to the front of the extending pseudopodia from the perinuclear pool in Slug-transfected PANC-1 cells. These results suggest that Slug promotes migration and invasion of PANC-1 cells, which may correlate with the reorganization of MMP-9 and remodeling of the F-actin cytoskeleton, but not with E-cadherin expression.

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.

The role of radiotherapy in locally advanced pancreatic carcinoma

The prognosis for locally advanced pancreatic carcinoma remains dismal despite advances in chemotherapy and radiotherapy over the past few decades. The use of radiotherapy for pancreatic carcinoma is often disputed because of the hypothesis that patients with pancreatic cancer die from distant metastases. It is well accepted that the greatest chance for cure of pancreatic cancer involves surgical resection of the primary tumor. However, there is much controversy about the role of radiotherapy in local disease control. The aim of this Review is to discuss data from the available studies, both prospective and retrospective, that evaluate treatment options for locally advanced pancreatic cancer. We focus on the benefits associated with local therapies, including radiotherapy and surgical resection, as they relate to improved local disease control, prolonged overall survival and improved symptom control.

Gemcitabine in combination with dendritic cell-induced immunoeffector cells inhibits the growth of BxPC-3 cells

AIM: To investigate the effect of gemcitabine (GEM) in combination with T lymphocytes activated by BxPC-3 cell whole lysate-pulsed dendritic cells (DCs) on the growth of BxPC-3 cells.

METHODS: After T lymphocytes were incubated with monocyte-derived DCs sensitized with whole lysate of BxPC-3 cells, the concentrations of IL-2, IFN-γ, TNF-α, IL-10 and TGF-β in cell supernatants were measured by enzyme-linked immunosorbent assay (ELISA). Subsequently, GEM and activated T lymphocytes, alone or in combination, were added into cultured BxPC-3 cells. After incubation for 24 h, BxPC-3 cell proliferation was measured by methyl thiazolyl tetrazolium (MTT) assay and colony formation assay, and early apoptosis of BxPC-3 cells was detected by flow cytometry.

RESULTS: After stimulation with sensitized DCs, the secretion of IL-2, IFN-γ and TNF-α by T lymphocytes was significantly enhanced (1 379 ng/L ± 307 ng/L vs 370 ng/L ± 64 ng/L, 1 269 ng/L ± 264 ng/L vs 420 ± 114 ng/L, and 1 062 ng/L ± 172 ng/L vs 515 ± 27 ng/L, all P < 0.01), while the production of IL-10 and TGF-β showed no significant changes (both P > 0.05). Compared with the negative control group, activated T lymphocytes and GEM, alone or in combination, could inhibit the growth of BxPC-3 cells. The death rate and apoptosis rate were highest, and the rate of colony formation was lowest in BxPC-3 cells treated with activated T lymphocytes and GEM in combination.

CONCLUSION: DCs sensitized with BxPC-3 cell whole lysate can induce the formation of tumor-killing cytotoxic T cells. Dendritic cell-induced immunoeffector cells in combination with gemcitabine have stronger tumor-killing activity than immunoeffector cells alone.

Tailored cancer immunotherapy using combinations of chemotherapy and a mixture of antibodies against EGF-receptor ligands

Growth factors are implicated in several processes essential for cancer progression. Specifically, growth factors that bind to ErbB family receptors have been implicated in cell proliferation and in resistance of solid tumors to chemotherapy. We quantified ligand secretion by several human cancer cell lines, and generated mAbs against two ligands, namely TGF-alpha and heparin-binding EGF-like growth factor. These growth factors are frequently secreted by pancreatic tumor cell lines, including BxPC3 cells. The monoclonal antibodies were tested for their antigen specificity and ability to inhibit growth of BxPC3 cells in vitro. Combining the two antibodies resulted in enhanced inhibition of BxPC3 cell growth, both in vitro and in tumor-bearing animals. Hence, we combined the two antibodies with gemcitabine, an effective chemotherapeutic drug commonly used to treat pancreatic cancer patients. Because treatment with a combination of two monoclonal antibodies enhanced the ability of chemotherapy to inhibit BxPC3 tumors in mice, we propose a general cancer therapeutic strategy that entails profiling the repertoire of growth factors secreted by a tumor, and combining with chemotherapy several antibodies capable of blocking autocrine ligands.

Gemcitabine combined with gum mastic causes potent growth inhibition and apoptosis of pancreatic cancer cells

AIM

To investigate the antiproliferative and apoptotic effects of gemcitabine combined with gum mastic and the underlying mechanisms in human pancreatic cancer cell lines.

METHODS

Cell proliferation and apoptosis were examined using the methyl thiazolyl tetrazolium (MTT) assay and propidium iodine staining, respectively. The expression of Bcl-2, Bax, NF-kappaB p65 subunit, and IkappaBalpha protein was measured using Western blotting.

RESULTS

Gemcitabine 0.01-100 microg/mL inhibited cell proliferation and induced apoptosis in both pancreatic cancer BxPC-3 and COLO 357 cells. Gum mastic 40 microg/mL significantly potentiated the antiproliferative and apoptotic effects of gemcitabine 10 microg/mL after 72-h treatment. When cells were treated with gemcitabine in combination with gum mastic, the IkappaBalpha level was increased, whereas NF-kappaB activation was blocked; the expression of Bax protein was substantially increased, but Bcl-2 protein was down-regulated.

CONCLUSION

Gemcitabine combined with gum mastic causes potent apoptosis in pancreatic cancer cells. The combination may be an effective therapeutic strategy for pancreatic cancer.

Extended pancreatic resections and lymphadenectomy: An appraisal of the current evidence

Surgery remains the mainstay of treatment for pancreatic ductal adenocarcinoma and complete removal of the cancer confers a definite survival advantage, especially in early disease. However, the majority of patients do not present with early disease, thus precluding the chance of a cure by standard pancreatoduodenectomy (PD), distal pancreatectomy or total pancreatectomy. For this reason, pancreatic surgeons have attempted to push the limits of resection over the last three decades. The aim of these resections has been to determine whether obtaining a complete resection by extending the limits of conventional resection in patients with advanced disease will yield the results seen with PD alone in early disease. This article revisits the data from such studies in an attempt to determine if the available literature supports the performance of extended resections for pancreatic cancer in terms of improvement of survival.

Management of pancreatic cancer: Current status and future directions

Despite advances in surgery and adjuvant therapy pancreatic ductal adenocarcinoma has a dismal prognosis. Surgical resection with negative margins remains the mainstay of treatment, and results can be improved with neoadjuvant therapy when the lesion is of borderline resectability. Extended lymphadenectomy has no role in improving survival, but may worsen quality of life. Venous resection can be performed if it helps to achieve an R0 resection, but arterial resection is not justified. A host of newer agents, both cytotoxic and targeted, are being evaluated. The article summarizes the critical issues and looks ahead to the future.