Emerging pathways and future targets for the molecular therapy of pancreatic cancer

ArticleinExpert Opinion on Therapeutic Targets 15(10):1183-96 · August 2011with9 Reads
DOI: 10.1517/14728222.2011.607438 · Source: PubMed
Introduction: Pancreatic cancer treatment remains a challenge for clinicians and researchers. Despite undisputable advances in the comprehension of the molecular mechanisms underlying cancer development and progression, early disease detection and clinical management of patients has made little, if any, progress in the past 20 years. Clinical development of targeted agents directed against validated pathways, such as the EGF/EGF receptor axis, the mutant KRAS protein, MMPs, and VEGF-mediated angiogenesis, alone or in combination with gemcitabine-based standard chemotherapy, has been disappointing. Areas covered: This review explores the preclinical rationale for clinical approaches aimed at targeting the TGF-β, IGF, Hedgehog, Notch and NF-κB signaling pathways, to develop innovative therapeutic strategies for pancreatic cancer. Expert opinion: Although some of the already clinically explored approaches (particularly EGFR and KRAS targeting) deserve further clinical consideration, by employing more innovative and creative clinical trial designs than the gemcitabine-targeted agent paradigm that has thus far invariably failed, the targeting of emerging and relatively unexplored signaling pathways holds great promise to increase our understanding of the complex molecular biology and to advance the clinical management of pancreatic cancer.
    • "Most pancreatic cancer patients are usually presented at an advanced stage once being diagnosed [3]. Currently, there are very few therapeutic options available for pancreatic cancer patients due to limited response or resistance to available systemic treatments [4]. At present, gemcitabine is the first-line chemotherapeutic agent for advanced and metastatic pancreatic cancers. "
    [Show abstract] [Hide abstract] ABSTRACT: As the standard therapy for pancreatic cancer, gemcitabine shows limited efficacy in pancreatic cancer patients because of chemoresistance. Aberrant expression of Bmi1 has been reported to activate multiple growth-regulatory pathways and confer anti-apoptotic abilities to many cancer cells. However, the role of Bmi1 in response of pancreatic cancer cells towards gemcitabine resistance remains elusive. In this study, we found that certain dose of gemcitabine treatment induced Bmi1 expression in pancreatic cancer cells. Knockdown of Bmi1 enhanced ROS production and promoted the cytotoxic effect of gemcitabine. The increased oxidative stress upon gemcitabine treatment could disrupt mitochondrial membrane and decrease mitochondrial membrane potential, eventually leading to apoptosis. Bmi1 inhibition also suppressed the activation of NF-κB signaling and the expressions of downstream molecules in pancreatic cancer cells treated with gemcitabine. Moreover, we observed Bmi1 inhibition sensitized the pancreatic xenograft tumors to gemcitabine in vivo. Taken together, our study demonstrated that Bmi1 could decrease the sensitivity of pancreatic cancer cells to gemcitabine through increasing oxidative stress and inhibiting NF-κB signaling, thus Bmi1 may serve as a promising target for sensitizing pancreatic cancer cells to chemotherapy.
    Full-text · Article · Apr 2016
    Tao YinTao YinZhengle ZhangZhengle ZhangBin CaoBin Cao+1more author...[...]
    • "Negative results for this combination were also observed in the adjuvant setting [66]. Insulin-Like Growth Factor Receptor (IGF-R) Blockade Blockade of IGF-R1 is underpinned by strong pre-clinical data [67, 68] . Ganitumab, Amgen's human monoclonal antibody that targets IGF-1R, was studied in combination with gemcitabine in a Phase II trial of 42 patients with metastatic disease. "
    [Show abstract] [Hide abstract] ABSTRACT: Over the last couple of years, we have witnessed the availability of a wide variety of different therapeutic agents and the identification of effective combinations of existing ones that have transformed the way we approach and treat pancreatic cancer. Proof of this are the recent validations that combinations of conventional chemotherapy drugs, the FOLFIRINOX regimen and gemcitabine plus nab-paclitaxel, significantly improves clinical outcomes in patients with metastatic disease. However, deeper and more sophisticated understanding of the biology of this cancer as well as the ability to develop better and perhaps more precise drugs predict that the landscape may be changing even more. In this review, we will summarize the most recent treatment advances including FOLFIRINOX, gemcitabine plus nab-paclitaxel and discuss novel approaches such as immune-mediated therapies, drugs that disrupt the tumor-stromal compartment, PARP inhibitors for BRCA pathway-deficient pancreatic cancer and new generations of conventional chemotherapeutics, which are in early phases of clinical development and have shown promising early results. We will also discuss some examples of drugs that failed, despite very good preliminary data, in order to appraise the lessons learned from these negative clinical trials. Lastly, we will comment on ongoing adjuvant and neoadjuvant trials. We hope that at least some of these will result in positive trials and add to our armamentarium for treating this challenging malignancy.
    Full-text · Article · Dec 2013
    • "More than half of PDAC tumors also exhibit loss of the functional tumor suppressor gene, deleted in pancreatic cancer, locus 4 (DPC4), either due to homozygous deletion or intragenic mutations, and up to 75% of PDAC have a p53 mutation [4]. As found with other solid tumors, PDAC shows aberrant over-expression and/or constitutive activation of a number of growth factor receptors [5]. "
    [Show abstract] [Hide abstract] ABSTRACT: Among the solid tumors, human pancreatic ductal adenocarcinoma (PDAC) has the worst prognosis. Gemcitabine is the standard first line of therapy for pancreatic cancer but has limited efficacy due to inherent or rapid development of resistance and combining EGFR inhibitors with this regimen results in only a modest clinical benefit. The goal of this study was to identify molecular targets that are activated during gemcitabine therapy alone or in combination with an EGFR inhibitor. PDAC cell lines were used to determine molecular changes and rates of growth after treatment with gemcitabine or an EGFR inhibitor, AG1478, by Western blot analysis and MTT assays respectively. Flow cytometric analysis was performed to study the cell cycle progression and rate of apoptosis after gemcitabine treatment. ShRNA was used to knockdown STAT3. An in vivo orthotopic animal model was used to evaluate STAT3 as a target. Immunohistochemical analysis was performed to analyze Ki67 and STAT3 expression in tumors. Treatment with gemcitabine increased the levels of EGFRTyr1068 and ERK phosphorylation in the PDAC cell lines tested. The constitutive STAT3Tyr705 phosphorylation observed in PDAC cell lines was not altered by treatment with gemcitabine. Treatment of cells with gemcitabine or AG1478 resulted in differential rate of growth inhibition. AG1478 efficiently blocked the phosphorylation of EGFRTyr1068 and inhibited the phosphorylation of down-stream effectors AKT and ERKs, while STAT3Tyr705 phosphorylation remained unchanged. Combining these two agents neither induced synergistic growth suppression nor inhibited STAT3Tyr705 phosphorylation, thus prompting further studies to assess whether targeting STAT3 improves the response to gemcitabine or AG1478. Indeed, knockdown of STAT3 increased sensitivity to gemcitabine by inducing pro-apoptotic signals and by increasing G1 cell cycle arrest. However, knockdown of STAT3 did not enhance the growth inhibitory potential of AG1478. In vivo orthotopic animal model results show that knockdown of STAT3 caused a significant reduction in tumor burden and delayed tumor progression with increased response to gemcitabine associated with a decrease in the Ki-67 positive cells. This study suggests that STAT3 should be considered an important molecular target for therapy of PDAC for enhancing the response to gemcitabine.
    Full-text · Article · Sep 2013
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