Involvement of host stroma cells and tissue fibrosis in pancreatic tumor development in transgenic mice

Pancreatic cancer derived 3D organoids as a clinical tool to evaluate the treatment response

Background and purpose

Pancreatic cancer (PC) is the fourth leading cause of cancer death in both men and women. The standard of care for patients with locally advanced PC of chemotherapy, stereotactic radiotherapy (RT), or chemo-radiation-therapy has shown highly variable and limited success rates. However, three-dimensional (3D) Pancreatic tumor organoids (PTOs) have shown promise to study tumor response to drugs, and emerging treatments under in vitro conditions. We investigated the potential for using 3D organoids to evaluate the precise radiation and drug dose responses of in vivo PC tumors.

Methods

PTOs were created from mouse pancreatic tumor tissues, and their microenvironment was compared to that of in vivo tumors using immunohistochemical and immunofluorescence staining. The organoids and in vivo PC tumors were treated with fractionated X-ray RT, 3-bromopyruvate (3BP) anti-tumor drug, and combination of 3BP + fractionated RT.

Results

Pancreatic tumor organoids (PTOs) exhibited a similar fibrotic microenvironment and molecular response (as seen by apoptosis biomarker expression) as in vivo tumors. Untreated tumor organoids and in vivo tumor both exhibited proliferative growth of 6 folds the original size after 10 days, whereas no growth was seen for organoids and in vivo tumors treated with 8 (Gray) Gy of fractionated RT. Tumor organoids showed reduced growth rates of 3.2x and 1.8x when treated with 4 and 6 Gy fractionated RT, respectively. Interestingly, combination of 100 µM of 3BP + 4 Gy of RT showed pronounced growth inhibition as compared to 3-BP alone or 4 Gy of radiation alone. Further, positive identification of SOX2, SOX10 and TGFβ indicated presence of cancer stem cells in tumor organoids which might have some role in resistance to therapies in pancreatic cancer.

Conclusions

PTOs produced a similar microenvironment and exhibited similar growth characteristics as in vivo tumors following treatment, indicating their potential for predicting in vivo tumor sensitivity and response to RT and combined chemo-RT treatments.

Comprehensive bioinformatic analysis reveals a cancer-associated fibroblast gene signature as a poor prognostic factor and potential therapeutic target in gastric cancer

BACKGROUND

Gastric cancer is one of the deadliest cancers, currently available therapies have limited success. Cancer-associated fibroblasts (CAFs) are pivotal cells in the stroma of gastric tumors posing a great risk for progression and chemoresistance. The poor prognostic signature for CAFs is not clear in gastric cancer, and drugs that target CAFs are lacking in the clinic. In this study, we aim to identify a poor prognostic gene signature for CAFs, targeting which may increase the therapeutic success in gastric cancer.

METHODS

We analyzed four GEO datasets with a network-based approach and validated key CAF markers in The Cancer Genome Atlas (TCGA) and The Asian Cancer Research Group (ACRG) cohorts. We implemented stepwise multivariate Cox regression guided by a pan-cancer analysis in TCGA to identify a poor prognostic gene signature for CAF infiltration in gastric cancer. Lastly, we conducted a database search for drugs targeting the signature genes.

RESULTS

Our study revealed the COL1A1, COL1A2, COL3A1, COL5A1, FN1, and SPARC as the key CAF markers in gastric cancer. Analysis of the TCGA and ACRG cohorts validated their upregulation and poor prognostic significance. The stepwise multivariate Cox regression elucidated COL1A1 and COL5A1, together with ITGA4, Emilin1, and TSPAN9 as poor prognostic signature genes for CAF infiltration. The search on drug databases revealed collagenase clostridium histolyticum, ocriplasmin, halofuginone, natalizumab, firategrast, and BIO-1211 as the potential drugs for further investigation.

CONCLUSIONS

Our study demonstrated the central role of extracellular matrix components secreted and remodeled by CAFs in gastric cancer. The gene signature we identified in this study carries high potential as a predictive tool for poor prognosis in gastric cancer patients. Elucidating the mechanisms by which the signature genes contribute to poor patient outcomes can lead to the discovery of more potent molecular-targeted agents and increase the therapeutic success in gastric cancer.

Orally Administered Halofuginone-Loaded TPGS Polymeric Micelles Against Triple-Negative Breast Cancer: Enhanced Absorption and Efficacy with Reduced Toxicity and Metastasis

Background

Halofuginone (HF)-loaded TPGS polymeric micelles (HTPM) were successfully fabricated using the thin-film hydration technique. HTPM via intravenous injection have been demonstrated to exert an excellent anticancer effect against triple-negative breast cancer (TNBC) cells and subcutaneous xenografts. In the present study, we further explored the potential treatment effect and mechanism of orally administered HTPM alone and in combination with surgical therapy on TNBC in subcutaneous and orthotopic mouse models.

Methods

Herein, the stability and in vitro release behavior of HTPM were first evaluated in the simulated gastrointestinal fluids. Caco-2 cell monolayers were then used to investigate the absorption and transport patterns of HF with/without encapsulation in TPGS polymeric micelles. Subsequently, the therapeutic effect of orally administered HTPM was checked on subcutaneous xenografts of TNBC in nude mice. Ultimately, orally administered HTPM, combined with surgical therapy, were utilized to treat orthotopic TNBC in nude mice.

Results

Our data confirmed that HTPM exhibited good stability and sustained release in the simulated gastrointestinal fluids. HF was authenticated to be a substrate of P-glycoprotein (P-gp), and its permeability across Caco-2 cell monolayers was markedly enhanced via heightening intracellular absorption and inhibiting P-gp efflux due to encapsulation in TPGS polymeric micelles. Compared with HF alone, HTPM showed stronger tumor-suppressing effects in subcutaneous xenografts of MDA-MB-231 cells when orally administered. Moreover, compared with HTPM or surgical therapy alone, peroral HTPM combined with partial surgical excision synergistically retarded the growth of orthotopic TNBC. Fundamentally, HTPM orally administered at the therapeutic dose did not cause any pathological injury, while HF alone led to weight loss and jejunal bleeding in the investigated mice.

Conclusion

Taken together, HTPM could be applied as a potential anticancer agent for TNBC by oral administration.

Halofuginone, a promising drug for treatment of pulmonary hypertension

BACKGROUND AND PURPOSE

Halofuginone is a febrifugine derivative originally isolated from Chinese traditional herb Chang Shan that exhibits anti-hypertrophic, anti-fibrotic and anti-proliferative effects. We sought to investigate whether halofuginone induced pulmonary vasodilation and attenuates chronic hypoxia-induced pulmonary hypertension (HPH).

EXPERIMENTAL APPROACH

Patch-clamp experiments were conducted to examine the activity of voltage-dependent Ca²⁺ channels (VDCCs) in pulmonary artery smooth muscle cells (PASMCs). Digital fluorescence microscopy was used to measure intracellular Ca²⁺ concentration in PASMCs. Isolated perfused and ventilated mouse lungs were used to measure pulmonary artery pressure (PAP). Mice exposed to hypoxia (10% O₂ ) for 4 weeks were used as model of HPH for in vivo experiments.

KEY RESULTS

Halofuginone increased voltage-gated K⁺ (K_v ) currents in PASMCs and K⁺ currents through KCNA5 channels in HEK cells transfected with KCNA5 gene. HF (0.03-1 μM) inhibited receptor-operated Ca²⁺ entry in HEK cells transfected with calcium-sensing receptor gene and attenuated store-operated Ca²⁺ entry in PASMCs. Acute (3-5 min) intrapulmonary application of halofuginone significantly and reversibly inhibited alveolar hypoxia-induced pulmonary vasoconstriction dose-dependently (0.1-10 μM). Intraperitoneal administration of halofuginone (0.3 mg·kg^-1 , for 2 weeks) partly reversed established PH in mice.

CONCLUSION AND IMPLICATIONS

Halofuginone is a potent pulmonary vasodilator by activating K_v channels and blocking VDCC and receptor-operated and store-operated Ca²⁺ channels in PASMCs. The therapeutic effect of halofuginone on experimental PH is probably due to combination of its vasodilator effects, via inhibition of excitation-contraction coupling and anti-proliferative effects, via inhibition of the PI3K/Akt/mTOR signalling pathway.

Diversity and Biology of Cancer-Associated Fibroblasts

Efforts to develop anti-cancer therapies have largely focused on targeting the epithelial compartment, despite the presence of non-neoplastic stromal components that substantially contribute to the progression of the tumor. Indeed, cancer cell survival, growth, migration, and even dormancy are influenced by the surrounding tumor microenvironment (TME). Within the TME, cancer-associated fibroblasts (CAFs) have been shown to play several roles in the development of a tumor. They secrete growth factors, inflammatory ligands, and extracellular matrix proteins that promote cancer cell proliferation, therapy resistance, and immune exclusion. However, recent work indicates that CAFs may also restrain tumor progression in some circumstances. In this review, we summarize the body of work on CAFs, with a particular focus on the most recent discoveries about fibroblast heterogeneity, plasticity, and functions. We also highlight the commonalities of fibroblasts present across different cancer types, and in normal and inflammatory states. Finally, we present the latest advances regarding therapeutic strategies targeting CAFs that are undergoing preclinical and clinical evaluation.

A promotive effect for halofuginone on membrane repair and synaptotagmin-7 levels in muscle cells of dysferlin-null mice

In the absence of dysferlin, skeletal muscle cells fail to reseal properly after injury, resulting in slow progress of the dysferlinopathy muscular dystrophy (MD). Halofuginone, a leading agent in preventing fibrosis in MDs, was tested for its effects on membrane resealing post-injury. A hypo-osmotic shock assay on myotubes derived from wild-type (Wt) and dysferlin-null (dysf-/-) mice revealed that pre-treatment with halofuginone reduces the percentage of membrane-ruptured myotubes only in dysf-/- myotubes. In laser-induced injury of isolated myofibers, halofuginone decreased the amount of FM1-43 at the injury site of dysf-/- myofibers while having no effect on Wt myofibers. These results implicate halofuginone in ameliorating muscle-cell membrane integrity in dysf-/- mice. Halofuginone increased lysosome scattering across the cytosol of dysf-/- primary myoblasts, in a protein kinase/extracellular signal-regulated protein kinase and phosphoinositide 3 kinase/Akt-dependent manner, in agreement with an elevation in lysosomal exocytotic activity in these cells. A spatial- and age-dependent synaptotagmin-7 (Syt-7) expression pattern was shown in dysf-/- versus Wt mice, suggesting that these pattern alterations are related to the disease progress and that sytnaptotagmin-7 may be compensating for the lack of dysferlin at least with regard to membrane resealing post-injury. While halofuginone did not affect patch-repair-complex key proteins, it further enhanced Syt-7 levels and its spread across the cytosol in dysf-/- myofibers and muscle tissue, and increased its co-localization with lysosomes. Together, the data imply a novel role for halofuginone in membrane-resealing events with Syt-7 possibly taking part in these events.

Antifibrotic Therapy Disrupts Stromal Barriers and Modulates the Immune Landscape in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDA) remains one of the deadliest forms of cancer, in part, because it is largely refractory to current therapies. The failure of most standard therapies in PDA, as well as promising immune therapies, may be largely ascribed to highly unique and protective stromal microenvironments that present significant biophysical barriers to effective drug delivery, that are immunosuppressive, and that can limit the distribution and function of antitumor immune cells. Here, we utilized stromal reengineering to disrupt these barriers and move the stroma toward normalization using a potent antifibrotic agent, halofuginone. In an autochthonous genetically engineered mouse model of PDA, halofuginone disrupted physical barriers to effective drug distribution by decreasing fibroblast activation and reducing key extracellular matrix elements that drive stromal resistance. Concomitantly, halofuginone treatment altered the immune landscape in PDA, with greater immune infiltrate into regions of low hylauronan, which resulted in increased number and distribution of both classically activated inflammatory macrophages and cytotoxic T cells. In concert with a direct effect on carcinoma cells, this led to widespread intratumoral necrosis and reduced tumor volume. These data point to the multifunctional and critical role of the stroma in tumor protection and survival and demonstrate how compromising tumor integrity to move toward a more normal physiologic state through stroma-targeting therapy will likely be an instrumental component in treating PDA. SIGNIFICANCE: This work demonstrates how focused stromal re-engineering approaches to move toward normalization of the stroma disrupt physical barriers to effective drug delivery and promote antitumor immunity.See related commentary by Huang and Brekken, p. 328.

Loss of Sirt2 increases and prolongs a caerulein-induced pancreatitis permissive phenotype and induces spontaneous oncogenic Kras mutations in mice

Mice lacking Sirt2 spontaneously develop tumors in multiple organs, as well as when expressed in combination with oncogenic KrasG12D, leading to pancreatic tumors. Here, we report that after caerulein-induced pancreatitis, Sirt2-deficient mice exhibited an increased inflammatory phenotype and delayed pancreatic tissue recovery. Seven days post injury, the pancreas of Sirt2-/- mice display active inflammation, whereas wild-type mice had mostly recovered. In addition, the pancreas from the Sirt2-/- mice exhibited extensive tissue fibrosis, which was still present at six weeks after exposure. The mice lacking Sirt2 also demonstrated an enhanced whole body pro-inflammatory phenotype that was most obvious with increasing age. Importantly, an accumulation of a cell population with spontaneous cancerous KrasG12D mutations was observed in the Sirt2-/- mice that is enhanced in the recovering pancreas after exposure to caerulein. Finally, transcriptome analysis of the pancreas of the Sirt2-/- mice exhibited a pro-inflammatory genomic signature. These results suggest that loss of Sirt2, as well as increased age, enhanced the immune response to pancreatic injury and induced an inflammatory phenotype permissive for the accumulation of cells carrying oncogenic Kras mutations.

Trefoil factor 1 inhibits epithelial-mesenchymal transition of pancreatic intraepithelial neoplasm

The tumor-suppressive role of trefoil factor family (TFF) members in gastric carcinogenesis has been suggested, but their significance and mechanisms in other digestive diseases remain elusive. To clarify the role of TFF1 in pancreatic carcinogenesis, we performed IHC on human samples, transfected siRNA against TFF1 into pancreatic cancer cell lines, and employed mouse models in which PanIN development and loss of TFF1 occur simultaneously. In human samples, the expression of TFF1 was specifically observed in pancreatic intraepithelial neoplasm (PanIN), but was frequently lost in the invasive component of pancreatic ductal adenocarcinoma (PDAC). When the expression of TFF1 was suppressed in vitro, pancreatic cancer cell lines showed enhanced invasive ability and features of epithelial-mesenchymal transition (EMT), including upregulated Snail expression. TFF1 expression was also observed in PanIN lesions of Pdx-1 Cre; LSL-KRASG12D (KC) mice, a model of pancreatic cancer, and loss of TFF1 in these mice resulted in the expansion of PanIN lesions, an EMT phenotype in PanIN cells, and an accumulation of cancer-associated fibroblasts (CAFs), eventually resulting in the development of invasive adenocarcinoma. This study indicates that the acquisition of TFF1 expression is an early event in pancreatic carcinogenesis and that TFF1 might act as a tumor suppressor to prevent EMT and the invasive transformation of PanIN.

Antifibrotic effects of pentoxifylline improve the efficacy of gemcitabine in human pancreatic tumor xenografts

We investigated the combinatorial effects of pentoxifylline (PTX) on the efficacy of gemcitabine (GEM) in a human pancreatic tumor xenograft model. PTX significantly improved the efficacy of GEM, as shown by a 50% reduction in tumor growth rate at 4 weeks of treatment compared with that in animals given GEM alone. The fluorescent drug doxorubicin (DOX) was used to test whether drug delivery was improved by PTX, contributing to the improved efficacy of GEM. PTX given for 2 weeks prior to giving DOX improved drug distribution by 1.8‐ to 2.2‐fold with no changes in vessel density, suggesting that improvement in drug delivery was not related to the vascular mechanism. Instead, collagen I content in tumor stroma was significantly reduced, as was the expression of alpha‐smooth muscle actin of cancer‐associated fibroblasts and connective tissue growth factor (CTGF) by PTX pretreatment. Overall, our data demonstrated that increased efficacy of GEM by PTX was associated with improved drug delivery to tumor tissue, which may be attributed to decreased expression of CTGF and subsequent reduction in the stromal collagen matrix in the pancreatic ductal adenocarcinoma tumor. These results support the usefulness of PTX in combination with chemotherapy for targeting drug delivery barriers associated with the stromal matrix, which should be further evaluated for clinical development.

Seed-in-Soil: Pancreatic Cancer Influenced by Tumor Microenvironment

Pancreatic ductal adenocarcinoma is a fatal malignancy with a five-year survival rate lower than 7%, and most patients dying within six months of diagnosis. The factors that contribute to the aggressiveness of the disease include, but are not limited to: late diagnosis, prompt metastasis to adjacent vital organs, poor response, and resistance to anticancer treatments. This malignancy is uniquely associated with desmoplastic stroma that accounts for 80% of tumor mass. Understanding the biology of stroma can aid the discovery of innovative strategies for eradicating this lethal cancer in the future. This review highlights the critical components in the stroma and how they interact with the cancer cells to convey the devastating tumor progression.

Clustering of patients with intrahepatic cholangiocarcinoma based on serum periostin may be predictive of prognosis

An effective serum biomarker may improve cholangiocarcinoma (CCA) management. Periostin (PN) has been demonstrated to be associated with aggressive CCA. The current study evaluated PN in blood serum for its diagnostic and prognostic potential in patients with CCA. Sera of 68 patients with CCA were collected prior to treatment, and PN levels were measured using an ELISA. Sera from 50 normal controls, 6 patients with benign liver diseases, 2 with hepatocellular carcinoma and 21 with breast cancer were analyzed. Immunohistochemistry of PN in CCA tissues was also investigated. The data were analyzed using the Mann-Whitney U test, Kaplan-Meier log rank tests, Cox proportional hazard regression models and Fisher's exact tests. The median serum PN level in patients with CCA was significantly increased compared with that in healthy controls, patients with benign liver diseases and patients with breast cancer (all P<0.05). Using an optimal threshold value of 94 ng/ml PN, the diagnostic values for CCA compared with other conditions demonstrated a sensitivity level of 0.38 [95% confidence interval (CI), 0.27-0.51], specificity of 0.90 (95% CI, 0.81-0.96), accuracy of 0.66 (95% CI, 0.58-0.74), positive predictive value of 0.76 (95% CI, 0.59-0.89) and negative predictive value of 0.63 (95% CI, 0.53-0.72) (P<0.001). Furthermore, PN stain in stromal fibroblasts in CCA tissues was associated with serum PN levels (P=0.001), and patients with CCA were classified as low (≤94 ng/ml) or high PN (>94 ng/ml) accordingly. High serum and tissue PN levels were significantly associated with reduced survival rate (P<0.001 and P=0.033, respectively). Serum PN was an independent prognostic factor with a hazard ratio of 3.197 (P=0.001). In conclusion, serum PN may be used to divide patients with intrahepatic CCA into high and low PN groups. Elevated serum PN may be utilized as a marker of poor prognosis in patients with CCA.

Improved Treatment of Pancreatic Cancer With Drug Delivery Nanoparticles Loaded With a Novel AKT/PDK1 Inhibitor

OBJECTIVES

This research study sought to improve the treatment of pancreatic cancer by improving the drug delivery of a promising AKT/PDK1 inhibitor, PHT-427, in poly(lactic-co-glycolic) acid (PLGA) nanoparticles.

METHODS

PHT-427 was encapsulated in single-emulsion and double-emulsion PLGA nanoparticles (SE-PLGA-427 and DE-PLGA-427). The drug release rate was evaluated to assess the effect of the second PLGA layer of DE-PLGA-427. Ex vivo cryo-imaging and drug extraction from ex vivo organs was used to assess the whole-body biodistribution in an orthotopic model of MIA PaCa-2 pancreatic cancer. Anatomical magnetic resonance imaging (MRI) was used to noninvasively assess the effects of 4 weeks of nanoparticle drug treatment on tumor size, and diffusion-weighted MRI longitudinally assessed changes in tumor cellularity.

RESULTS

DE-PLGA-427 showed delayed drug release and longer drug retention in the pancreas relative to SE-PLGA-427. Diffusion-weighted MRI indicated a consistent decrease in cellularity during drug treatment with both types of drug-loaded nanoparticles. Both SE- and DE-PLGA-427 showed a 6-fold and 4-fold reduction in tumor volume relative to untreated tumors and an elimination of primary pancreatic tumor in 68% of the mice.

CONCLUSIONS

These results indicated that the PLGA nanoparticles improved drug delivery of PHT-427 to pancreatic tumors, which improved the treatment of MIA PaCa-2 pancreatic cancer.

The conflicting roles of tumor stroma in pancreatic cancer and their contribution to the failure of clinical trials: a systematic review and critical appraisal

A nearly universal feature of pancreatic ductal adenocarcinoma (PDAC) is an extensive presence of activated stroma. This stroma is thought to aid in various tumor-promoting processes and hampers response to therapy. Here, we aim to evaluate the evidence that supports this role of the stroma in PDAC with functional experiments in relevant models, discuss the clinical trials that have aimed to target the stroma in this disease, and examine recent work that explains why these clinical trials based on stroma-targeting strategies have thus far not achieved the expected success. We systematically searched PubMed through August 2014 with no restrictions to identify published peer-reviewed research articles assessing the effect of targeting the stroma on tumor growth or metastases in preclinical animal models. Five hundred and thirty articles were extracted of which 31 were included in the analysis. Unfortunately, due to the large variety in models and outcome measures, we could not perform a meta-analysis of our data. We find that despite an abundance of positive outcomes reported in previous studies on stroma targeting, a strong discrepancy exists with the outcomes of clinical trials and the more recent preclinical work that is in line with these trials. We explain the incongruities by the duration of stroma targeting and propose that chronic stroma targeting treatment is possibly detrimental in the treatment of this disease.

Gemcitabine-releasing mesenchymal stromal cells inhibit in vitro proliferation of human pancreatic carcinoma cells

BACKGROUND AIMS

Pancreatic cancer (pCa) is a tumor characterized by a fibrotic state and associated with a poor prognosis. The observation that mesenchymal stromal cells (MSCs) migrate toward inflammatory micro-environments and engraft into tumor stroma after systemic administration suggested new therapeutic approaches with the use of engineered MSCs to deliver and produce anti-cancer molecules directly within the tumor. Previously, we demonstrated that without any genetic modifications, MSCs are able to deliver anti-cancer drugs. MSCs loaded with paclitaxel by exposure to high concentrations release the drug both in vitro and in vivo, inhibiting tumor proliferation. On the basis of these observations, we evaluated the ability of MSCs (from bone marrow and pancreas) to uptake and release gemcitabine (GCB), a drug widely used in pCa treatment.

METHODS

MSCs were primed by 24-h exposure to 2000 ng/mL of GCB. The anti-tumor potential of primed MSCs was then investigated by in vitro anti-proliferation assays with the use of CFPAC-1, a pancreatic tumor cell line sensitive to GCB. The uptake/release ability was confirmed by means of high-performance liquid chromatography analysis. A cell-cycle study and secretome evaluation were also conducted to better understand the characteristics of primed MSCs.

RESULTS

GCB-releasing MSCs inhibit the growth of a human pCa cell line in vitro.

CONCLUSIONS

The use of MSCs as a "trojan horse" can open the way to a new pCa therapeutic approach; GCB-loaded MSCs that integrate into the tumor mass could deliver much higher concentrations of the drug in situ than can be achieved by intravenous injection.

Suppression of tumor growth in mice by rationally designed pseudopeptide inhibitors of fibroblast activation protein and prolyl oligopeptidase

Tumor microenvironments (TMEs) are composed of cancer cells, fibroblasts, extracellular matrix, microvessels, and endothelial cells. Two prolyl endopeptidases, fibroblast activation protein (FAP) and prolyl oligopeptidase (POP), are commonly overexpressed by epithelial-derived malignancies, with the specificity of FAP expression by cancer stromal fibroblasts suggesting FAP as a possible therapeutic target. Despite overexpression in most cancers and having a role in angiogenesis, inhibition of POP activity has received little attention as an approach to quench tumor growth. We developed two specific and highly effective pseudopeptide inhibitors, M83, which inhibits FAP and POP proteinase activities, and J94, which inhibits only POP. Both suppressed human colon cancer xenograft growth > 90% in mice. By immunohistochemical stains, M83- and J94-treated tumors had fewer microvessels, and apoptotic areas were apparent in both. In response to M83, but not J94, disordered collagen accumulations were observed. Neither M83- nor J94-treated mice manifested changes in behavior, weight, or gastrointestinal function. Tumor growth suppression was more extensive than noted with recently reported efforts by others to inhibit FAP proteinase function or reduce FAP expression. Diminished angiogenesis and the accompanying profound reduction in tumor growth suggest that inhibition of either FAP or POP may offer new therapeutic approaches that directly target TMEs.

Halofuginone - the multifaceted molecule

Halofuginone is an analog of febrifugine-an alkaloid originally isolated from the plant Dichroa febrifuga. During recent years, halofuginone has attracted much attention because of its wide range of beneficial biological activities, which encompass malaria, cancer, and fibrosis-related and autoimmune diseases. At present two modes of halofuginone actions have been described: (1) Inhibition of Smad3 phosphorylation downstream of the TGFβ signaling pathway results in inhibition of fibroblasts-to-myofibroblasts transition and fibrosis. (2) Inhibition of prolyl-tRNA synthetase (ProRS) activity in the blood stage of malaria and inhibition of Th17 cell differentiation thereby inhibiting inflammation and the autoimmune reaction by activation of the amino acid starvation and integrated stress responses. This review deals with the history and origin of this natural product, its synthesis, its known modes of action, and it's various biological activities in pre-clinical animal models and in humans.

Perspectives of TGF-β inhibition in pancreatic and hepatocellular carcinomas

Advanced pancreatic ductal adenocarcinoma (PDAC) and hepatocellular carcinoma (HCC) are non-curable diseases with a particularly poor prognosis. Over the last decade, research has increasingly focused on the microenvironment surrounding cancer cells, and its role in tumour development and progression. PDAC and HCC differ markedly regarding their pathological features: PDAC are typically stromal-predominant, desmoplastic, poorly vascularized tumours, whereas HCC are cellular and highly vascularized. Despite these very different settings, PDAC and HCC share transforming growth factor-β (TGF-β) as a common key-signalling mediator, involved in epithelial-to-mesenchymal transition, invasion, and stroma-tumour dialogue. Recently, novel drugs blocking the TGF-β pathway have entered clinical evaluation demonstrating activity in patients with advanced PDAC and HCC. TGF-β signalling is complex and mediates both pro- and anti-tumoural activities in cancer cells depending on their context, in space and time, and their microenvironment. In this review we provide a comprehensive overview of the role of the TGF-β pathway and its deregulation in PDAC and HCC development and progression at the cellular and microenvironment levels. We also summarize key preclinical and clinical data on the role of TGF-β as a target for therapeutic intervention in PDAC and HCC, and explore perspectives to optimize TGF-β inhibition therapy.

Transforming growth factor-β1 gene expression in hepatocellular carcinoma: a preliminary report

BACKGROUND AND STUDY AIMS

The transforming growth factor (TGF)-β signalling pathway plays a dual role in hepatocarcinogenesis. It has been recognised for its role as a tumour suppressor as well as a tumour promoter depending on the cellular context. The aim of this study was to investigate the clinical significance of serum TGF-β1 level and TGF-β1 messenger RNA (mRNA) in the peripheral blood of liver cirrhosis and hepatocellular carcinoma (HCC) patients as noninvasive biomarkers in diagnosing HCC.

PATIENTS AND METHODS

Twenty patients were allocated to each of the liver cirrhosis and HCC groups, in addition to 20 healthy volunteers. TGF-β1 gene expression in peripheral blood was quantitated using real-time polymerase chain reaction (PCR), while serum TGF-β1 was analysed using enzyme-linked immunosorbent assay (ELISA).

RESULTS

TGF-β1 gene expression was significantly lower in HCC patients (median 0.401 (0.241-0.699) fold change) than in liver cirrhosis patients (median 0.595 (0.464-0.816)) (p=0.042) and normal controls (median 1.00 (0.706-1.426) fold change) (p=0.001). TGF-β1 gene expression showed significant positive correlation with serum TGF-β1 (r=0.272, p=0.036) and significant negative correlation with alpha-fetoprotein (AFP) (r=-0.528, p=0.001). Receiver operating characteristic (ROC) analysis was conducted for TGF-β1 gene expression in comparison with AFP. The area under the curve for TGF-β1 gene expression was 0.688 (95% CI=0.517-0.858) (p=0.042) and AFP was 0.869 (95% CI=0.761-0.976) (p=0.001). The sensitivity and specificity of TGF-β1 gene expression were 65% and 75%, respectively, at a cutoff value of 0.462 fold change.

CONCLUSION

TGF-β1 gene expression in the peripheral blood may be used as a molecular marker for the diagnosis of HCC. Additional studies on a large-scale population are necessary to gain greater insight into the impact of TGF-β1 gene expression in the pathogenesis of HCC.

SIBLINGs and SPARC families: Their emerging roles in pancreatic cancer

Pancreatic cancer has a considerably poor prognosis with a 5-year survival probability of less than 5% when all stages are combined. Pancreatic cancer is characterized by its dense stroma, which is involved in the critical interplay with the tumor cells throughout tumor progression and furthermore, creates a barrier restricting efficient penetration of therapeutics. Alterations in a large number of genes are reflected by a limited number of signaling pathways, which are potential targets. Understanding more about the molecular basis of this devastating cancer type regarding tumor microenvironment, distinct subpopulations of cells, epithelial-to-mesenchymal transition and inflammation will lead to the development of various targeted therapies for controlling tumor growth and metastasis. In this complex scenario of pancreatic cancer, especially members of the “small integrin binding ligand N-linked glycoproteins” (SIBLINGs) and “secreted protein acidic and rich in cysteine” (SPARC) families have emerged due to their prominent roles in properties including proliferation, differentiation, apoptosis, adhesion, migration, angiogenesis, wound repair and regulation of extracellular matrix remodeling. SIBLINGs consist of five members, which include osteopontin (OPN), bone sialoprotein, dentin matrix protein 1, dentin sialophosphoprotein and matrix extracellular phosphoglycoprotein. The SPARC family of modular extracellular proteins is comprised of SPARC/osteonectin (ON) and SPARC-like 1 (hevin); secreted modular calcium binding proteins; testicans and follistatin-like protein. In this review, we especially focus on OPN and ON, elaborating on their special and growing importance in pancreatic cancer diagnosis and prognosis.

Halofuginone for fibrosis, regeneration and cancer in the gastrointestinal tract

Organ fibrosis and architectural remodeling can severely disrupt tissue function, often with fatal consequences. Fibrosis is the end result of chronic inflammatory reactions induced by a variety of stimuli, and the key cellular mediator of fibrosis comprises the myofibroblasts which, when activated, serve as the primary collagen-producing cells. Complex links exist between fibrosis, regeneration and carcinogenesis, and the concept that all organs contain common tissue fibrosis pathways that could be potential therapeutic targets is an attractive one. Because of the major impact of fibrosis on human health there is an unmet need for safe and effective therapies that directly target fibrosis. Halofuginone inhibits tissue fibrosis and regeneration, and thereby affects the development of tumors in various tissues along the gastrointestinal tract. The high efficacy of halofuginone in reducing the fibrosis that affects tumor growth and tissue regeneration is probably due to its dual role in inhibiting the signaling pathway of transforming growth factor β, on the one hand, and inhibiting the development of Th17 cells, on the other hand. At present halofuginone is being evaluated in a clinical trial for other fibrotic indication, and any clinical success in that trial would allow the use of halofuginone, also for all other fibrotic indications, including those of the gastrointestinal tract.

Halofuginone improves muscle-cell survival in muscular dystrophies

Halofuginone has been shown to prevent fibrosis via the transforming growth factor-β/Smad3 pathway in muscular dystrophies. We hypothesized that halofuginone would reduce apoptosis--the presumed cause of satellite-cell depletion during muscle degradation-in the mdx mouse model of Duchenne muscular dystrophy. Six-week-old mdx mouse diaphragm exhibited fourfold higher numbers of apoptotic nuclei compared with wild-type mice as determined by a TUNEL assay. Apoptotic nuclei were found in macrophages and in Pax7-expressing cells; some were located in centrally-nucleated regenerating myofibers. Halofuginone treatment of mdx mice reduced the apoptotic nuclei number in the diaphragm, together with reduction in Bax and induction in Bcl2 levels in myofibers isolated from these mice. A similar effect was observed when halofuginone was added to cultured myofibers. No apparent effect of halofuginone was observed in wild-type mice. Inhibition of apoptosis or staurosporine-induced apoptosis by halofuginone in mdx primary myoblasts and C2 myogenic cell line, respectively, was reflected by less pyknotic/apoptotic cells and reduced Bax expression. This reduction was reversed by a phosphinositide-3-kinase and mitogen-activated protein kinase/extracellular signal-regulated protein kinase inhibitors, suggesting involvement of these pathways in mediating halofuginone's effects on apoptosis. Halofuginone increased apoptosis in α smooth muscle actin- and prolyl 4-hydroxylase β-expressing cells in mdx diaphragm and in myofibroblasts, the major source of extracellular matrix. The data suggest an additional mechanism by which halofuginone improves muscle pathology and function in muscular dystrophies.

Pancreatic cancer stroma: Understanding biology leads to new therapeutic strategies

Pancreatic ductal adenocarcinoma (PDA) is among the deadliest cancers in the United States and in the world. Late diagnosis, early metastasis and lack of effective therapy are among the reasons why only 6% of patients diagnosed with PDA survive past 5 years. Despite development of targeted therapy against other cancers, little progression has been made in the treatment of PDA. Therefore, there is an urgent need for the development of new treatments. However, in order to proceed with treatments, the complicated biology of PDA needs to be understood first. Interestingly, majority of the tumor volume is not made of malignant epithelial cells but of stroma. In recent years, it has become evident that there is an important interaction between the stromal compartment and the less prevalent malignant cells, leading to cancer progression. The stroma not only serves as a growth promoting source of signals but it is also a physical barrier to drug delivery. Understanding the tumor-stroma signaling leading to development of desmoplastic reaction and tumor progression can lead to the development of therapies to decrease stromal activity and improve drug delivery. In this review, we focus on how the current understanding of biology of the pancreatic tumor microenvironment can be translated into the development of targeted therapy.

The chemistry and biology of febrifugine and halofuginone

The trans-2,3-disubstituted piperidine, quinazolinone-containing natural product febrifugine (also known as dichroine B) and its synthetic analogue, halofuginone, possess antimalarial activity. More recently studies have also shown that halofuginone acts as an agent capable of reducing fibrosis, an indication with clinical relevance for several disease states. This review summarizes historical isolation studies and the chemistry performed which culminated in the correct structural elucidation of naturally occurring febrifugine and its isomer isofebrifugine. It also includes the range of febrifugine analogues prepared for antimalarial evaluation, including halofuginone. Finally, a section detailing current opinion in the field of halofuginone's human biology is included.