FGF21 in obesity and cancer: New insights.

The endocrine FGF21 was discovered as a novel metabolic regulator in 2005 with new functions bifurcating from the canonic heparin-binding FGFs that directly promote cell proliferation and growth independent of a co-receptor. Early studies have demonstrated that FGF21 is a stress sensor in the liver and possibly, several other endocrine and metabolic tissues. Hepatic FGF21 signals via endocrine routes to quench episodes of metabolic derangements, promoting metabolic homeostasis. The convergence of mouse and human studies shows that FGF21 promotes lipid catabolism, including lipolysis, fatty acid oxidation, mitochondrial oxidative activity, and thermogenic energy dissipation, rather than directly regulating insulin and appetite. The white and brown adipose tissues and, to some extent, the hypothalamus, all of which host a transmembrane receptor binary complex of FGFR1 and co-receptor KLB, are considered the essential tissue and molecular targets of hepatic or pharmacological FGF21. On the other hand, a growing body of work has revealed that pancreatic acinar cells form a constitutive high-production site for FGF21, which then acts in an autocrine or paracrine mode. Beyond regulation of macronutrient metabolism and physiological energy expenditure, FGF21 appears to function in forestalling the development of fatty pancreas, steato-pancreatitis, fatty liver, and steato-hepatitis, thereby preventing the development of advanced pathologies such as pancreatic ductal adenocarcinoma or hepatocellular carcinoma. This review is intended to provide updates on these new discoveries that illuminate the protective roles of FGF21-FGFR1-KLB signal pathway in metabolic anomalies-associated severe tissue damage and malignancy, and to inform potential new preventive or therapeutic strategies for obesity-inflicted cancer patients via reducing metabolic risks and inflammation.

Vitamin C and Vitamin E Mitigate the Risk of Pancreatic Ductal Adenocarcinoma from Meat-Derived Mutagen Exposure in Adults in a Case-Control Study.

BACKGROUND: Previous studies have found that meat-derived mutagens increase, and vitamin C or E decrease, the risk of pancreatic cancer. OBJECTIVE: The aim of this study was to determine whether intake of vitamin C or E modulates the association between meat-derived mutagen exposure and risk of pancreatic cancer. DESIGN: We conducted a case-control study in 1321 patients with pathologically confirmed pancreatic ductal adenocarcinoma (PDAC) and 1061 healthy controls (aged 28-88 y). Cases and controls were frequency-matched by age, sex, and race/ethnicity. Mutagen intake was assessed using a meat preparation questionnaire. Intakes of vitamin C, E, and other dietary components were assessed via a food-frequency questionnaire in a subset of 811 cases and 818 controls. ORs and 95% CIs were estimated in multivariable-adjusted logistic regression models. RESULTS: The risk of PDAC was not associated with meat intake but was associated with consumption of well-done grilled or barbecued chicken (OR: 1.57; 95% CI: 1.18, 2.09; P = 0.001). Intake of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline was associated with increased PDAC risk (Ptrend = 0.047). Participants in the highest, as compared with the lowest, quintile of 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (PhIP) intake experienced a 38% increased risk of PDAC (95% CI: 1.00, 1.90; P = 0.048). Intakes of total vitamin C or E from food and supplements or from supplements alone were each inversely associated with PDAC risk. Stratified analyses showed differential associations for PhIP intake and PDAC risk, such that risk increased among individuals with lower intake of vitamin C or E and decreased among those with higher vitamin intake. Significant interactions of dietary vitamin C, dietary vitamin E, and total vitamin E with PhIP intake were detected (Pinteraction = 0.023, <0.001, and 0.013, respectively). CONCLUSIONS: Consistent with experimental evidence, this study of 811 cases and 818 controls has shown that high intake of dietary vitamin C or E mitigates the risk of PhIP-related PDAC.

RN1, a novel galectin-3 inhibitor, inhibits pancreatic cancer cell growth in vitro and in vivo via blocking galectin-3 associated signaling pathways.

Galectin-3 (Gal-3) has been implicated in pancreatic ductal adenocarcinoma (PDAC), and its candidacy as a therapeutic target has been evaluated. Gal-3 is widely upregulated in tumors, and its expression is associated with the development and malignancy of PDAC. In the present study, we demonstrate that a polysaccharide, RN1, purified from the flower of Panax notoginseng binds to Gal-3 and suppresses its expression. In addition, RN1 markedly inhibits PDAC cells growth in vitro, in vivo and in patient-derived xenografts. Mechanistically, RN1 binds to epidermal growth factor receptor (EGFR) and Gal-3, thereby disrupting the interaction between Gal-3 and EGFR and downregulating extracellular-related kinase (ERK) phosphorylation and the transcription factor of Gal-3, Runx1 expression. Inhibiting the expression of Runx1 by RN1, suppresses Gal-3 expression and inactivates Gal-3-associated signaling pathways, including the EGFR/ERK/Runx1, BMP/smad/Id-3 and integrin/FAK/JNK signaling pathways. In addition, RN1 can also bind to bone morphogenetic protein receptors (BMPR1A and BMPR2) and block the interaction between Gal-3 and the BMPRs. Thus, our results suggest that a novel Gal-3 inhibitor RN1 may be a potential candidate for human PDAC treatment via multiple targets and multiple signaling pathways.

Ablation of sensory neurons in a genetic model of pancreatic ductal adenocarcinoma slows initiation and progression of cancer.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by an exuberant inflammatory desmoplastic response. The PDAC microenvironment is complex, containing both pro- and antitumorigenic elements, and remains to be fully characterized. Here, we show that sensory neurons, an under-studied cohort of the pancreas tumor stroma, play a significant role in the initiation and progression of the early stages of PDAC. Using a well-established autochthonous model of PDAC (PKC), we show that inflammation and neuronal damage in the peripheral and central nervous system (CNS) occurs as early as the pancreatic intraepithelial neoplasia (PanIN) 2 stage. Also at the PanIN2 stage, pancreas acinar-derived cells frequently invade along sensory neurons into the spinal cord and migrate caudally to the lower thoracic and upper lumbar regions. Sensory neuron ablation by neonatal capsaicin injection prevented perineural invasion (PNI), astrocyte activation, and neuronal damage, suggesting that sensory neurons convey inflammatory signals from Kras-induced pancreatic neoplasia to the CNS. Neuron ablation in PKC mice also significantly delayed PanIN formation and ultimately prolonged survival compared with vehicle-treated controls (median survival, 7.8 vs. 4.5 mo; P = 0.001). These data establish a reciprocal signaling loop between the pancreas and nervous system, including the CNS, that supports inflammation associated with oncogenic Kras-induced neoplasia. Thus, pancreatic sensory neurons comprise an important stromal cell population that supports the initiation and progression of PDAC and may represent a potential target for prevention in high-risk populations.

Triptolide reverses hypoxia-induced epithelial-mesenchymal transition and stem-like features in pancreatic cancer by NF-κB downregulation.

Pancreatic ductal adenocarcinoma (PDA) is one of the most lethal malignancies characterized by an intense tumor stroma with hypoperfused regions, a significant inflammatory response and pronounced therapy resistance. New therapeutic agents are urgently needed. The plant-derived agent triptolide also known as "thunder god vine" has a long history in traditional Chinese medicine for treatment of rheumatoid arthritis and cancer and is now in a clinical phase II trial for establishing the efficacy against a placebo. The authors mimicked the situation in patient tumors by induction of hypoxia in experimental models of pancreatic cancer stem cells (CSCs) and evaluated the therapeutic effect of triptolide. Hypoxia led to induction of colony and spheroid formation, aldehyde dehydrogenase 1 (ALDH1) and NF-κB activity, migratory potential and a switch in morphology to a fibroblastoid phenotype, as well as stem cell- and epithelial-mesenchymal transition-associated protein expression. Triptolide efficiently inhibited hypoxia-induced transcriptional signaling and downregulated epithelial-mesenchymal transition (EMT) and CSC features in established highly malignant cell lines, whereas sensitive cancer cells or nonmalignant cells were less affected. In vivo triptolide inhibited tumor take and tumor growth. In primary CSCs isolated from patient tumors, triptolide downregulated markers of CSCs, proliferation and mesenchymal cells along with upregulation of markers for apoptosis and epithelial cells. This study is the first to show that triptolide reverses EMT and CSC characteristics and therefore may be superior to current chemotherapeutics for treatment of PDA.

Atorvastatin inhibits pancreatic carcinogenesis and increases survival in LSL-KrasG12D-LSL-Trp53R172H-Pdx1-Cre mice.

There are several studies supporting the role of HMG-CoA reductase inhibitors such as atorvastatin against carcinogenesis, in which inhibiting the generation of prenyl intermediates involved in protein prenylation plays the crucial role. Mutation of Kras gene is the most common genetic alteration in pancreatic cancer and the Ras protein requires prenylation for its membrane localization and activity. In the present study, the effectiveness of atorvastatin against pancreatic carcinogenesis and its effect on protein prenylation were determined using the LSL-KrasG12D-LSL-Trp53R172H-Pdx1-Cre mouse model (called Pankras/p53 mice). Five-week-old Pankras/p53 mice were fed either an AIN93M diet or a diet supplemented with 100 ppm atorvastatin. Kaplan-Meier survival analysis with Log-Rank test revealed a significant increase in survival in mice fed 100 ppm atorvastatin (171.9 ± 6.2 d) compared to the control mice (144.9 ± 8.4 d, P < 0.05). Histologic and immunohistochemical analysis showed that atorvastatin treatment resulted in a significant reduction in tumor volume and Ki-67-labeled cell proliferation. Mechanistic studies on primary pancreatic tumors and the cultured murine pancreatic carcinoma cells revealed that atorvastatin inhibited prenylation in several key proteins, including Kras protein and its activities, and similar effect was observed in pancreatic carcinoma cells treated with farnesyltransferase inhibitor R115777. Microarray assay on the global gene expression profile demonstrated that a total of 132 genes were significantly modulated by atorvastatin; and Waf1p21, cyp51A1, and soluble epoxide hydrolase were crucial atorvastatin-targeted genes which involve in inflammation and carcinogenesis. This study indicates that atorvastatin has the potential to serve as a chemopreventive agent against pancreatic carcinogenesis.

The angiotensin-I-converting enzyme inhibitor enalapril and aspirin delay progression of pancreatic intraepithelial neoplasia and cancer formation in a genetically engineered mouse model of pancreatic cancer.

BACKGROUND AND AIMS: There are no chemopreventive strategies for pancreatic cancer or its precursor lesions, pancreatic intraepithelial neoplasia (PanINs). Recent evidence suggests that aspirin and inhibitors of angiotensin-I converting enzyme (ACE inhibitors) have potential chemopreventive properties. In this study, we used a genetically engineered mouse model of pancreatic cancer to evaluate the chemopreventive potential of these drugs. METHODS: Drug treatment was initiated at the age of 5 weeks. LsL-Kras(G12D); Pdx1-Cre or LsL-Kras(G12D); LsL-Trp53(R172H); Pdx1-Cre transgenic mice were randomly assigned to receive either mock treatment, aspirin, enalapril, or a combination of both. After 3 and 5 months, animals were killed. The effect of aspirin and enalapril was evaluated by histopathological analyses, immunostaining, and real-time PCR. RESULTS: After 3 and 5 months of treatment, enalapril and aspirin were able to significantly delay progression of mPanINs in LsL-Kras(G12D); Pdx1-Cre mice. Furthermore, development of invasive pancreatic cancer in LsL-Kras(G12D); LsL-Trp53(R172H); Pdx1-Cre transgenic mice was partially inhibited by enalapril and aspirin. Invasive pancreatic cancer was identified in 15 of 25 (60%) LsL-Kras(G12D); LsL-Trp53(R172H); Pdx1-Cre untreated control mice, but in only three of 17 (17.6%, p=0.01) mice treated with aspirin, in four of 17 (23.5%, p=0.03) in mice treated with enalapril alone, and in five of 16 (31.2%, p=0.11) mice treated with a combination of both drugs. Using real-time PCR we found a significant downregulation of the target genes VEGF and RelA demonstrating our ability to achieve effective pharmacological levels of aspirin and enalapril during pancreatic cancer formation in vivo. CONCLUSION: Using a transgenic mouse model that imitates human pancreatic cancer, this study provides first evidence that aspirin and enalapril are effective chemopreventive agents by delaying the progression of PanINs and partially inhibiting the formation of murine pancreatic cancer. This study together supports the hypothesis that aspirin and ACE inhibitors might be a valid chemopreventive strategy.

Progression of pancreatic adenocarcinoma is significantly impeded with a combination of vaccine and COX-2 inhibition.

With a 5-year survival rate of <5%, pancreatic cancer is one of the most rapidly fatal malignancies. Current protocols for the treatment of pancreas cancer are not as effective as we desire. In this study, we show that a novel Mucin-1 (MUC1)-based vaccine in combination with a cyclooxygenase-2 inhibitor (celecoxib), and low-dose chemotherapy (gemcitabine) was effective in preventing the progression of preneoplastic intraepithelial lesions to invasive pancreatic ductal adenocarcinomas. The study was conducted in an appropriate triple transgenic model of spontaneous pancreatic cancer induced by the KRAS(G12D) mutation and that expresses human MUC1 as a self molecule. The combination treatment elicited robust antitumor cellular and humoral immune responses and was associated with increased apoptosis in the tumor. The mechanism for the increased immune response was attributed to the down-regulation of circulating prostaglandin E(2) and indoleamine 2, 3,-dioxygenase enzymatic activity, as well as decreased levels of T regulatory and myeloid suppressor cells within the tumor microenvironment. The preclinical data provide the rationale to design clinical trials with a combination of MUC1-based vaccine, celecoxib, and gemcitabine for the treatment of pancreatic cancer.

Prophylactic hepatic irradiation following curative resection of pancreatic cancer.

BACKGROUND/PURPOSE: It is unlikely that adjuvant chemoradiotherapy applied to the pancreatic bed alone significantly improves the survival of patients with resectable pancreatic cancer. The aim of the present study was to determine whether prophylactic hepatic irradiation (PHI) improved patient outcome after the curative resection of pancreatic cancer. METHODS: The study population was comprised of 34 patients (PHI group) who were administered PHI after curative resection of pancreatic cancer between September 1994 and December 2003. The whole liver was irradiated with a total dose of 19.8-22.0 Gy under continuous infusion of 5-fluorouracil. The cumulative rate of liver metastasis and the survival outcomes of the PHI group were compared with those of 31 patients without PHI (non-PHI group) who underwent curative resection of pancreatic cancer. RESULTS: The planned PHI was completed for 32 of the 34 patients. Two patients developed complications that might have been PHI-related. One developed liver abscesses which were successfully managed by percutaneous drainage. The other died of liver failure without recurrence 11 months after the operation. The cumulative incidence of liver metastasis was significantly lower for the PHI group than the non-PHI group (P=0.0455). Patients in the PHI group also survived significantly longer compared to those in the non-PHI group (P=0.0002). CONCLUSIONS: The present findings suggest that PHI is well tolerated and is a potentially effective treatment strategy after curative resection of pancreatic cancer, thereby providing the basis for a randomized controlled trial.