Disruption of the antiproliferative TGF-beta signaling pathways in human pancreatic cancer cells

Crosstalk of TGF-β and somatostatin signaling in adenocarcinoma and neuroendocrine tumors of the pancreas: a brief review

Although the vast majority of cancers affecting the human pancreas are pancreatic ductal adenocarcinomas (PDAC), there are several other cancer types originating from non-exocrine cells of this organ, i.e., pancreatic neuroendocrine tumors (panNET). Genomic analyses of PDAC and panNET revealed that certain signaling pathways such as those triggered by transforming growth factor-β (TGF-β) are frequently altered, highlighting their crucial role in pancreatic tumor development. In PDAC, TGF-β plays a dual role acting as a tumor suppressor in healthy tissue and early stages of tumor development but as a promoter of tumor progression in later stages. This peptide growth factor acts as a potent inducer of epithelial-to-mesenchymal transition (EMT), a developmental program that transforms otherwise stationary epithelial cells to invasive mesenchymal cells with enhanced metastatic potential. TGF-β signals through both the canonical Smad pathway involving the receptor-regulated Smad proteins, SMAD2 and SMAD3, and the common-mediator Smad, SMAD4, as well as Smad-independent pathways, i.e., ERK1/2, PI3K/AKT, and somatostatin (SST). Accumulating evidence indicates an intimate crosstalk between TGF-β and SST signaling, not only in PDAC but, more recently, also in panNET. In this work, we review the available evidence on signaling interactions between both pathways, which we believe are of potential but as yet insufficiently appreciated importance for pancreatic cancer development and/or progression as well as novel therapeutic approaches.

Radiogenomics and machine learning predict oncogenic signaling pathways in glioblastoma

BACKGROUND

Glioblastoma (GBM) is a highly aggressive brain tumor associated with a poor patient prognosis. The survival rate remains low despite standard therapies, highlighting the urgent need for novel treatment strategies. Advanced imaging techniques, particularly magnetic resonance imaging (MRI), are crucial in assessing GBM. Disruptions in various oncogenic signaling pathways, such as Receptor Tyrosine Kinase (RTK)-Ras-Extracellular signal-regulated kinase (ERK) signaling, Phosphoinositide 3- Kinases (PI3Ks), tumor protein p53 (TP53), and Neurogenic locus notch homolog protein (NOTCH), contribute to the development of different tumor types, each exhibiting distinct morphological and phenotypic features that can be observed at a microscopic level. However, identifying genetic abnormalities for targeted therapy often requires invasive procedures, prompting exploration into non-invasive approaches like radiogenomics. This study explores the utility of radiogenomics and machine learning (ML) in predicting these oncogenic signaling pathways in GBM patients.

METHODS

We collected post-operative MRI scans (T1w, T1c, FLAIR, T2w) from the BRATS-19 dataset, including scans from patients with both GBM and LGG, linked to genetic and clinical data via TCGA and CPTAC. Signaling pathway data was manually extracted from cBioPortal. Radiomic features were extracted from four MRI modalities using PyRadiomics. Dimensionality reduction and feature selection were applied and Data imbalance was addressed with SMOTE. Five ML models were trained to predict signaling pathways, with Grid Search optimizing hyperparameters and 5-fold cross-validation ensuring unbiased performance. Each model's performance was evaluated using various metrics on test data.

RESULTS

Our results showed a positive association between most signaling pathways and the radiomic features derived from MRI scans. The best models achieved high AUC scores, namely 0.7 for RTK-RAS, 0.8 for PI3K, 0.75 for TP53, and 0.4 for NOTCH, and therefore, demonstrated the potential of ML models in accurately predicting oncogenic signaling pathways from radiomic features, thereby informing personalized therapeutic approaches and improving patient outcomes.

CONCLUSION

We present a novel approach for the non-invasive prediction of deregulation in oncogenic signaling pathways in glioblastoma (GBM) by integrating radiogenomic data with machine learning models. This research contributes to advancing precision medicine in GBM management, highlighting the importance of integrating radiomics with genomic data to understand tumor behavior and treatment response better.

Tumor heterogeneity: An oncogenic driver of PDAC progression and therapy resistance under stress conditions

Pancreatic ductal adenocarcinoma (PDAC) is a clinically challenging disease usually diagnosed at advanced or metastasized stage. By this year end, there are an expected increase in 62,210 new cases and 49,830 deaths in the United States, with 90% corresponding to PDAC subtype alone. Despite advances in cancer therapy, one of the major challenges combating PDAC remains tumor heterogeneity between PDAC patients and within the primary and metastatic lesions of the same patient. This review describes the PDAC subtypes based on the genomic, transcriptional, epigenetic, and metabolic signatures observed among patients and within individual tumors. Recent studies in tumor biology suggest PDAC heterogeneity as a major driver of disease progression under conditions of stress including hypoxia and nutrient deprivation, leading to metabolic reprogramming. We therefore advance our understanding in identifying the underlying mechanisms that interfere with the crosstalk between the extracellular matrix components and tumor cells that define the mechanics of tumor growth and metastasis. The bilateral interaction between the heterogeneous tumor microenvironment and PDAC cells serves as another important contributor that characterizes the tumor-promoting or tumor-suppressing phenotypes providing an opportunity for an effective treatment regime. Furthermore, we highlight the dynamic reciprocating interplay between the stromal and immune cells that impact immune surveillance or immune evasion response and contribute towards a complex process of tumorigenesis. In summary, the review encapsulates the existing knowledge of the currently applied treatments for PDAC with emphasis on tumor heterogeneity, manifesting at multiple levels, impacting disease progression and therapy resistance under stress.

Increased risk of pancreatic cancer in individuals with non-alcoholic fatty liver disease

The association between non-alcoholic fatty liver disease (NAFLD) and the risk of pancreatic cancer in the general population remains unclear. This nationwide cohort study included 8,120,674 adults who underwent a national health screening in 2009 from the Korean National Health Insurance Service database. Participants were followed-up until December 2017 for the development of pancreatic cancer. NAFLD was assessed using the fatty liver index: ≥ 60, NAFLD and < 30, no NAFLD. Multivariable Cox proportional hazards regression was performed. During the follow-up of 59.1 million person-years, 10,470 participants were newly diagnosed with pancreatic cancer. NAFLD was significantly associated with an increased risk of pancreatic cancer compared to no NAFLD (adjusted hazard ratio [aHR], 1.17; 95% CI 1.09–1.26). This association was significant in both the obese (aHR, 1.14; 95% CI 1.05–1.23) and non-obese groups (aHR, 1.14; 95% CI 1.003–1.29). Individuals with fatty liver index 30–59 also had an increased risk (aHR, 1.10; 95% CI 1.05–1.16). The risk of pancreatic cancer increased with increasing fatty liver index scores (P for trend < 0.001). This study demonstrated that NAFLD was independently associated with an increased risk of pancreatic cancer, regardless of obesity. Our finding suggests that NAFLD may be a modifiable risk factor for pancreatic cancer.

Oncolytic adenovirus with hyaluronidase activity that evades neutralizing antibodies: VCN-11

Tumor targeting and intratumoral virus spreading are key features for successful oncolytic virotherapy. VCN-11 is a novel oncolytic adenovirus, genetically modified to express hyaluronidase (PH20) and display an albumin-binding domain (ABD) on the hexon. ABD allows the virus to self-coat with albumin when entering the bloodstream and evade neutralizing antibodies (NAbs). Here, we validate VCN-11 mechanism of action and characterize its toxicity. VCN-11 replication, hyaluronidase activity and binding to human albumin to evade NAbs was evaluated. Toxicity and efficacy of VCN-11 were assessed in mice and hamsters. Tumor targeting, and antitumor activity was analyzed in the presence of NAbs in several tumor models. VCN-11 induced 450 times more cytotoxicity in tumor cells than in normal cells. VCN-11 hyaluronidase production was confirmed by measuring PH20 activity in vitro and in virus-infected tumor areas in vivo. VCN-11 evaded NAbs from different sources and tumor targeting was demonstrated in the presence of high levels of NAbs in vivo, whereas the control virus without ABD was neutralized. VCN-11 showed a low toxicity profile in athymic nude mice and Syrian hamsters, allowing treatments with high doses and fractionated administrations without major toxicities (up to 1.2x10¹¹vp/mouse and 7.5x10¹¹vp/hamster). Fractionated intravenous administrations improved circulation kinetics and tumor targeting. VCN-11 antitumor efficacy was demonstrated in the presence of NAbs against Ad5 and itself. Oncolytic adenovirus VCN-11 disrupts tumor matrix and displays antitumor effects even in the presence of NAbs. These features make VCN-11 a safe promising candidate to test re-administration in clinical trials.

OncomiRs miR-106a and miR-17 negatively regulate the nucleoside-derived drug transporter hCNT1

High-affinity uptake of natural nucleosides as well as nucleoside derivatives used in anticancer therapies is mediated by human concentrative nucleoside transporters (hCNTs). hCNT1, the hCNT family member that specifically transports pyrimidines, is also a transceptor involved in tumor progression. In particular, oncogenesis appears to be associated with hCNT1 downregulation in some cancers, although the underlying mechanisms are largely unknown. Here, we sought to address changes in colorectal and pancreatic ductal adenocarcinoma-both of which are important digestive cancers-in the context of treatment with fluoropyrimidine derivatives. An analysis of cancer samples and matching non-tumoral adjacent tissues revealed downregulation of hCNT1 protein in both types of tumor. Further exploration of the putative regulation of hCNT1 by microRNAs (miRNAs), which are highly deregulated in these cancers, revealed a direct relationship between the oncomiRs miR-106a and miR-17 and the loss of hCNT1. Collectively, our findings provide the first demonstration that hCNT1 inhibition by these oncomiRs could contribute to chemoresistance to fluoropyrimidine-based treatments in colorectal and pancreatic cancer.

HisCoM-PAGE: Hierarchical Structural Component Models for Pathway Analysis of Gene Expression Data

Although there have been several analyses for identifying cancer-associated pathways, based on gene expression data, most of these are based on single pathway analyses, and thus do not consider correlations between pathways. In this paper, we propose a hierarchical structural component model for pathway analysis of gene expression data (HisCoM-PAGE), which accounts for the hierarchical structure of genes and pathways, as well as the correlations among pathways. Specifically, HisCoM-PAGE focuses on the survival phenotype and identifies its associated pathways. Moreover, its application to real biological data analysis of pancreatic cancer data demonstrated that HisCoM-PAGE could successfully identify pathways associated with pancreatic cancer prognosis. Simulation studies comparing the performance of HisCoM-PAGE with other competing methods such as Gene Set Enrichment Analysis (GSEA), Global Test, and Wald-type Test showed HisCoM-PAGE to have the highest power to detect causal pathways in most simulation scenarios.

Integrin-Mediated TGFβ Activation Modulates the Tumour Microenvironment

TGFβ (transforming growth factor-beta) is a pleotropic cytokine with contrasting effects in cancer. In normal tissue and early tumours, TGFβ acts as a tumour suppressor, limiting proliferation and inducing apoptosis. However, these effects are eventually abrogated by the loss or inactivation of downstream signalling within the TGFβ pathway, and in established tumours, TGFβ then acts as a tumour promotor through multiple mechanisms including inducing epithelial-to-mesenchymal transition (EMT), promoting formation of cancer-associated fibroblasts (CAFs) and increasing angiogenesis. TGFβ is secrereted as a large latent complex and is embedded in the extracellular matrix or held on the surface of cells and must be activated before mediating its multiple functions. Thus, whilst TGFβ is abundant in the tumour microenvironment (TME), its functionality is regulated by local activation. The αv-integrins are major activators of latent-TGFβ. The potential benefits of manipulating the immune TME have been highlighted by the clinical success of immune-checkpoint inhibitors in a number of solid tumour types. TGFβ is a potent suppressor of T-cell-mediated immune surveillance and a key cause of resistance to checkpoint inhibitors. Therefore, as certain integrins locally activate TGFβ, they are likely to have a role in the immunosuppressive TME, although this remains to be confirmed. In this review, we discussed the role of TGFβ in cancer, the role of integrins in activating TGFβ in the TME, and the potential benefits of targeting integrins to augment immunotherapies.

Loss of the transcriptional repressor TGIF1 results in enhanced Kras-driven development of pancreatic cancer

Background

The TG-interacting factor 1 (TGIF1) gene, which encodes a nuclear transcriptional corepressor of the TGFβ1/Smad signaling pathway, has been implicated in the pathogenesis of various types of human cancer; however, its role in pancreatic ductal adenocarcinoma (PDAC) has yet to be elucidated.

Methods

The expression of TGIF1 in human and murine PDAC specimens were detected by IHC analysis. The functions of TGIF1 in in vivo PDAC growth, dissemination, and metastasis were assessed using conditional inactivation of TGIF1 in well-established autochthonous mouse models of PDAC. Primary cells from TGIF1 null or wild type PDAC mice were examined by assays for cell proliferation, migration, invasion, soft agar and xenograft tumorigenesis. Gene expression profiling, pathway analyses, epigenetic changes associated with TGIF1 loss, and in vitro and in vivo effects of 4-MU were assessed.

Results

Conditional deletion of TGIF1 in the mouse pancreas had no discernible effect on pancreatic development or physiology. Notably, TGIF1 loss induced KrasG12D-driven PDAC models exhibited shorter latency and greater propensity for distant metastases. Deciphering the molecular mechanisms highlighted the TGIF1 loss-induced activation of the hyaluronan synthase 2 (HAS2)-CD44 signaling pathway and upregulation of the immune checkpoint regulator PD-L1 to facilitate the epithelial–mesenchymal transition (EMT) and tumor immune suppression. We also founded that TGIF1 might function as an epigenetic regulator and response for aberrant EMT gene expression during PDAC progression.

Conclusions

Our results imply that targeting the HAS2 pathway in TGIF1 loss of PDAC could be a promising therapeutic strategy for improving the clinical efficacy against PDAC metastasis.

Electronic supplementary material

The online version of this article (10.1186/s12943-019-1023-1) contains supplementary material, which is available to authorized users.

TGFβ receptor inhibitor galunisertib is linked to inflammation- and remodeling-related proteins in patients with pancreatic cancer

PURPOSE

Galunisertib, the first small molecule transforming growth factor beta (TGFβ) receptor inhibitor, plus gemcitabine resulted in the improvement of survival in patients with unresectable pancreatic cancer, but markers to identify patients likely to respond are lacking.

METHODS

In the Phase 1b/2 JBAJ study, 156 patients were randomized 2:1 to galunisertib + gemcitabine (N = 104) or placebo + gemcitabine (N = 52). Clinical outcome data were integrated with baseline markers and pharmacodynamic markers while patients were on treatment, including circulating proteins using a multi-analyte panel, T cell subset evaluation, and miRNA profiling.

RESULTS

Baseline biomarkers associated with overall prognosis regardless of treatment included CA19-9 and TGF-β1. In addition, IP-10, FSH, MIP-1α, and PAI-1 were potential predictive proteins. Baseline proteins that were changed during treatment included amphiregulin, CA15-3, cathepsin D, P-selectin, RAGE, sortilin, COMP, eotaxin-2, N-BNP, osteopontin, and thrombospondin-4. Plasma miRNA with potential prognostic value included miR-21-5p, miR-301a-3p, miR-210-3p, and miR-141-3p, while those with potential predictive value included miR-424-5p, miR-483-3p, and miR-10b-5p.

CONCLUSIONS

Galunisertib + gemcitabine resulted in improvement of overall survival, and 4 proteins (IP-10, FSH, MIP-1α, PAI-1) were potentially predictive for this combination treatment. Future studies should also include baseline evaluation of miR-424-5p, miR-483-3p, and miR-10b-5p.

TRIAL REGISTRATION

Clinicaltrials.gov NCT01373164.

Bioselection Reveals miR-99b and miR-485 as Enhancers of Adenoviral Oncolysis in Pancreatic Cancer

Oncolytic viruses are designed for cancer treatment. Cell-virus interactions are key determinants for successful viral replication. Therefore, the extensive reprogramming of gene expression that occurs in tumor cells might create a hurdle for viral propagation. We used a replication-based approach of a microRNA (miRNA) adenoviral library encoding up to 243 human miRNAs as a bioselection strategy to identify miRNAs that facilitate adenoviral oncolytic activity in pancreatic ductal adenocarcinoma. We identify two miRNAs, miR-99b and miR-485, that function as enhancers of adenoviral oncolysis by improving the intra- and extracellular yield of mature virions. An increased adenoviral activity is the consequence of enhanced E1A and late viral protein expression, which is probably mediated by the downregulation of the transcriptional repressors ELF4, MDM2, and KLF8, which we identify as miR-99b or miR-485 target genes. Arming the oncolytic adenovirus ICOVIR15 with miR-99b or miR-485 enhances its fitness and its antitumoral activity. Our results demonstrate the potential of this strategy to improve oncolytic adenovirus potency, and they highlight miR-99b and miR-485 as sensitizers of adenoviral replication.

Human Menstrual Blood-Derived Mesenchymal Stem Cells as Potential Cell Carriers for Oncolytic Adenovirus

Antitumor efficacy of systemically administered oncolytic adenoviruses (OAdv) is limited due to diverse factors such as liver sequestration, neutralizing interactions in blood, elimination by the immune system, and physical barriers in tumors. It is therefore of clinical relevance to improve OAdv bioavailability and tumor delivery. Among the variety of tumor-targeting strategies, the use of stem cells and specifically bone marrow-derived mesenchymal stem cells (BM-MSCs) is of particular interest due to their tumor tropism and immunomodulatory properties. Nonetheless, the invasive methods to obtain these cells, the low number of MSCs present in the bone marrow, and their restricted in vitro expansion represent major obstacles for their use in cancer treatments, pointing out the necessity to identify an alternative source of MSCs. Here, we have evaluated the use of menstrual blood-derived mesenchymal stem cells (MenSCs) as cell carriers for regional delivery of an OAdv in the tumor. Our results indicate that MenSCs can be isolated without invasive methods, they have an increased proliferation rate compared to BM-MSCs, and they can be efficiently infected with different serotype 5-based capsid-modified adenoviruses, leading to viral replication and release. In addition, our in vivo studies confirmed the tumor-homing properties of MenSCs after regional administration.

Inflammation and Epithelial-Mesenchymal Transition in Pancreatic Ductal Adenocarcinoma: Fighting Against Multiple Opponents

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer and one of the most lethal human cancers. Inflammation is a critical component in PDAC initiation and progression. Inflammation also contributes to the aggressiveness of PDAC indirectly via induction of epithelial-mesenchymal transition (EMT), altogether leading to enhanced resistance to chemotherapy and poor survival rates. This review gives an overview of the key pro-inflammatory signaling pathways involved in PDAC pathogenesis and discusses the role of inflammation in induction of EMT and development of chemoresistance in patients with PDAC.

[Inflammation and Cancer Development in Pancreatic and Biliary Tract Cancer]

Chronic inflammation has been known to be a risk for many kinds of cancers, including pancreatic and biliary tract cancer. Recently, inflammatory process has emerged as a key mediator of cancer development and progression. Many efforts with experimental results have been given to identify the underlying mechanisms that contribute to inflammation-induced tumorigenesis. Diverse inflammatory pathways have been investigated and inhibitors for inflammation-related signaling pathways have been developed for cancer treatment. This review will summarize recent outcomes about this distinctive process in pancreatic and biliary tract cancer. Taking this evidence into consideration, modulation of inflammatory process will provide useful options for pancreatic and biliary tract cancer treatment.

Self-renewal molecular mechanisms of colorectal cancer stem cells

Colorectal cancer stem cells (CCSCs) represent a small fraction of the colorectal cancer cell population that possess self-renewal and multi-lineage differentiation potential and drive tumorigenicity. Self-renewal is essential for the malignant biological behaviors of colorectal cancer stem cells. While the self-renewal molecular mechanisms of colorectal cancer stem cells are not yet fully understood, the aberrant activation of signaling pathways, such as Wnt, Notch, transforming growth factor-β (TGF-β)/bone morphogenetic protein (BMP) and Hedgehog-Gli (HH-GLI), specific roles mediated by cell surface markers and micro-environmental factors are involved in the regulation of self-renewal. The elucidation of the molecular mechanisms behind self-renewal may lead to the development of novel targeted interventions for the treatment of colorectal cancer.

The TGF-β Signalling Network in Muscle Development, Adaptation and Disease

Skeletal muscle possesses remarkable ability to change its size and force-producing capacity in response to physiological stimuli. Impairment of the cellular processes that govern these attributes also affects muscle mass and function in pathological conditions. Myostatin, a member of the TGF-β family, has been identified as a key regulator of muscle development, and adaptation in adulthood. In muscle, myostatin binds to its type I (ALK4/5) and type II (ActRIIA/B) receptors to initiate Smad2/3 signalling and the regulation of target genes that co-ordinate the balance between protein synthesis and degradation. Interestingly, evidence is emerging that other TGF-β proteins act in concert with myostatin to regulate the growth and remodelling of skeletal muscle. Consequently, dysregulation of TGF-β proteins and their associated signalling components is increasingly being implicated in muscle wasting associated with chronic illness, ageing, and inactivity. The growing understanding of TGF-β biology in muscle, and its potential to advance the development of therapeutics for muscle-related conditions is reviewed here.

Islet biology, the CDKN2A/B locus and type 2 diabetes risk

Type 2 diabetes, fuelled by the obesity epidemic, is an escalating worldwide cause of personal hardship and public cost. Diabetes incidence increases with age, and many studies link the classic senescence and ageing protein p16(INK4A) to diabetes pathophysiology via pancreatic islet biology. Genome-wide association studies (GWASs) have unequivocally linked the CDKN2A/B locus, which encodes p16 inhibitor of cyclin-dependent kinase (p16(INK4A)) and three other gene products, p14 alternate reading frame (p14(ARF)), p15(INK4B) and antisense non-coding RNA in the INK4 locus (ANRIL), with human diabetes risk. However, the mechanism by which the CDKN2A/B locus influences diabetes risk remains uncertain. Here, we weigh the evidence that CDKN2A/B polymorphisms impact metabolic health via islet biology vs effects in other tissues. Structured in a bedside-to-bench-to-bedside approach, we begin with a summary of the evidence that the CDKN2A/B locus impacts diabetes risk and a brief review of the basic biology of CDKN2A/B gene products. The main emphasis of this work is an in-depth look at the nuanced roles that CDKN2A/B gene products and related proteins play in the regulation of beta cell mass, proliferation and insulin secretory function, as well as roles in other metabolic tissues. We finish with a synthesis of basic biology and clinical observations, incorporating human physiology data. We conclude that it is likely that the CDKN2A/B locus influences diabetes risk through both islet and non-islet mechanisms.

Variant Profiling of Candidate Genes in Pancreatic Ductal Adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) has a poor prognosis. Variant profiling is crucial for developing personalized treatment and elucidating the etiology of this disease.

METHODS

Patients with PDAC undergoing surgery from 2007 to 2012 (n = 73) were followed from diagnosis until death or the end of the study. We applied an anchored multiplex PCR (AMP)-based next-generation sequencing (NGS) method to a panel of 65 selected genes and assessed analytical performance by sequencing a quantitative multiplex DNA reference standard. In clinical PDAC samples, detection of low-level KRAS (Kirsten rat sarcoma viral oncogene homolog) mutations was validated by allele-specific PCR and digital PCR. We compared overall survival of patients according to KRAS mutation status by log-rank test and applied logistic regression to evaluate the association between smoking and tumor variant types.

RESULTS

The AMP-based NGS method could detect variants with allele frequencies as low as 1% given sufficient sequencing depth (>1500×). Low-frequency KRAS G12 mutations (allele frequency 1%-5%) were all confirmed by allele-specific PCR and digital PCR. The most prevalent genetic alterations were in KRAS (78% of patients), TP53 (tumor protein p53) (25%), and SMAD4 (SMAD family member 4) (8%). Overall survival in T3-stage PDAC patients differed among KRAS mutation subtypes (P = 0.019). Transversion variants were more common in ever-smokers than in never-smokers (odds ratio 5.7; 95% CI 1.2-27.8).

CONCLUSIONS

The AMP-based NGS method is applicable for profiling tumor variants. Using this approach, we demonstrated that in PDAC patients, KRAS mutant subtype G12V is associated with poorer survival, and that transversion variants are more common among smokers.

TGF-β signaling in the control of hematopoietic stem cells

Blood is a tissue with high cellular turnover, and its production is a tightly orchestrated process that requires constant replenishment. All mature blood cells are generated from hematopoietic stem cells (HSCs), which are the self-renewing units that sustain lifelong hematopoiesis. HSC behavior, such as self-renewal and quiescence, is regulated by a wide array of factors, including external signaling cues present in the bone marrow. The transforming growth factor-β (TGF-β) family of cytokines constitutes a multifunctional signaling circuitry, which regulates pivotal functions related to cell fate and behavior in virtually all tissues of the body. In the hematopoietic system, TGF-β signaling controls a wide spectrum of biological processes, from homeostasis of the immune system to quiescence and self-renewal of HSCs. Here, we review key features and emerging concepts pertaining to TGF-β and downstream signaling pathways in normal HSC biology, featuring aspects of aging, hematologic disease, and how this circuitry may be exploited for clinical purposes in the future.

TGFβ signaling in pancreatic ductal adenocarcinoma

Transforming growth factor β (TGFβ) receptor signaling plays a paradoxical effect in the tumorigenesis of pancreatic ductal adenocarcinoma (PDAC), in which its tumor-inhibitory role at early stages turns into a tumor-promoting role at later stages. The underlying mechanism remains far from clear. Here we provide strong evidence that the activation of TGFβ receptor signaling in PDAC cells increased SMAD3 phosphorylation and nuclear translocation to inhibit cell growth. Meanwhile, it also activated SMAD7 to induce nuclear translocation and retention of β-catenin, which not only attenuated the inhibition of cell growth by nuclear SMAD3 but also activated vascular endothelial growth factor A (VEGF-A) to promote vascularization. Our data thus support a model involving crosstalk of the TGFβ and Wnt signaling pathways, for regulating the complicated effect of TGFβ signaling on the tumorigenesis of PDAC.

Safety and efficacy of VCN-01, an oncolytic adenovirus combining fiber HSG-binding domain replacement with RGD and hyaluronidase expression

PURPOSE

Tumor targeting upon intravenous administration and subsequent intratumoral virus dissemination are key features to improve oncolytic adenovirus therapy. VCN-01 is a novel oncolytic adenovirus that combines selective replication conditional to pRB pathway deregulation, replacement of the heparan sulfate glycosaminoglycan putative-binding site KKTK of the fiber shaft with an integrin-binding motif RGDK for tumor targeting, and expression of hyaluronidase to degrade the extracellular matrix. In this study, we evaluate the safety and efficacy profile of this novel oncolytic adenovirus.

EXPERIMENTAL DESIGN

VCN-01 replication and potency were assessed in a panel of tumor cell lines. VCN-01 tumor-selective replication was evaluated in human fibroblasts and pancreatic islets. Preclinical toxicity, biodistribution, and efficacy studies were conducted in mice and Syrian hamsters.

RESULTS

Toxicity and biodistribution preclinical studies support the selectivity and safety of VCN-01. Antitumor activity after intravenous or intratumoral administration of the virus was observed in all tumor models tested, including melanoma and pancreatic adenocarcinoma, both in immunodeficient mice and immunocompetent hamsters.

CONCLUSIONS

Oncolytic adenovirus VCN-01 characterized by the expression of hyaluronidase and the RGD shaft retargeting ligand shows an efficacy-toxicity prolife in mice and hamsters by intravenous and intratumoral administration that warrants clinical testing.

Meta-analysis of the prognostic value of smad4 immunohistochemistry in various cancers

Background

Accumulating evidence indicates that Smad4 (DPC4) plays a fundamental role in the development and prognosis of several types of cancer. The objective of this study was to conduct a meta-analysis to evaluate whether the loss of Smad4 staining could serve as a prognostic marker.

Methods

A comprehensive meta-analysis was conducted using major useful databases to determine the relationship between the immunohistochemical detection of Smad4 and the survival of patients with various cancers. We used hazard ratios (HRs) with 95% confidence interval (CIs) as the effect estimation to evaluate the association of Smad4 with overall survival (OS), cancer-specific survival (CSS) or recurrence-free survival (RFS). The relationship between the clinical characteristics of patients and Smad4 was also evaluated using the odds ratio (OR).

Results

A total of 7570 patients from 26 studies were included in the analysis. The pooled results showed that loss of Smad4 staining was a negative predictor of OS with an HR of 1.97 (95% CI: 1.55–2.51; P_{heterogeneity}<0.001) and CSS/RFS (HR = 1.81; 95% CI: 1.30–2.54; P_{heterogeneity}<0.001). In addition, loss of Smad4 staining was more likely to be found in older (OR = 1.69, 95% CI: 1.09–2.61; P_{heterogeneity} = 0.648) colorectal cancer patients with a late tumor stage (OR = 2.31, 95% CI: 1.71–3.10; P_{heterogeneity} = 0.218) and in gastric cancer patients with lymph node metastasis (OR = 2.11, 95% CI: 1.03–4.34; P_{heterogeneity} = 0.038).

Conclusion

Based on these results, our meta-analysis provided evidence that loss of Smad4 staining could act as an unfavorable biomarker in the prognosis of various cancers and should be used as a powerful tool in future clinical trials.

miR-148a- and miR-216a-regulated oncolytic adenoviruses targeting pancreatic tumors attenuate tissue damage without perturbation of miRNA activity

Oncolytic virotherapy shows promise for pancreatic ductal adenocarcinoma (PDAC) treatment, but there is the need to minimize associated-toxicities. In the current work, we engineered artificial target sites recognized by miR-216a and/or miR-148a to provide pancreatic tumor-selectivity to replication-competent adenoviruses (Ad-miRTs) and improve their safety profile. Expression analysis in PDAC patients identified miR-148a and miR-216a downregulated in resectable (FC(miR-148a) = 0.044, P < 0.05; FC(miR-216a) = 0.017, P < 0.05), locally advanced (FC(miR-148a) = 0.038, P < 0.001; FC(miR-216a) = 0.001, P < 0.001) and metastatic tumors (FC(miR-148a) = 0.041, P < 0.01; FC(miR-216a) = 0.002, P < 0.001). In mouse tissues, miR-216a was highly specific of the exocrine pancreas whereas miR-148a was abundant in the exocrine pancreas, Langerhans islets, and the liver. In line with the miRNA content and the miRNA target site design, we show E1A gene expression and viral propagation efficiently controlled in Ad-miRT-infected cells. Consequently, Ad-miRT-infected mice presented reduced pancreatic and liver damage without perturbation of the endogenous miRNAs and their targets. Interestingly, the 8-miR148aT design showed repressing activity by all miR-148/152 family members with significant detargeting effects in the pancreas and liver. Ad-miRTs preserved their oncolytic activity and triggered strong antitumoral responses. This study provides preclinical evidences of miR-148a and miR-216a target site insertions to confer adenoviral selectivity and proposes 8-miR148aT as an optimal detargeting strategy for genetically-engineered therapies against PDAC.

SMAD4 loss triggers the phenotypic changes of pancreatic ductal adenocarcinoma cells

BACKGROUND

SMAD4 is a gastrointestinal malignancy-specific tumor suppressor gene found mutated in one third of colorectal cancer specimens and half of pancreatic tumors. SMAD4 inactivation by allelic deletion or intragenic mutation mainly occurs in the late stage of human pancreatic ductal adenocarcinoma (PDAC). Various studies have proposed potential SMAD4-mediated anti-tumor effects in human malignancy; however, the relevance of SMAD4 in the PDAC molecular phenotype has not yet been fully characterized.

METHODS

The AsPC-1, CFPAC-1 and PANC-1 human PDAC cell lines were used. The restoration or knockdown of SMAD4 expression in PDAC cells were confirmed by western blotting, luciferase reporter and immunofluorescence assays. In vitro cell proliferation, xenograft, wound healing, quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR), Western blotting, and immunohistochemistry analysis were conducted using PDAC cells in which SMAD4 was either overexpressed or knocked down.

RESULTS

Here, we report that re-expression of SMAD4 in SMAD4-null PDAC cells does not affect tumor cell growth in vitro or in vivo, but significantly enhances cells migration in vitro. SMAD4 restoration transcriptionally activates the TGF-β1/Nestin pathway and induces expression of several transcriptional factors. In contrast, SMAD4 loss in PDAC leads to increased expression of E-cadherin, vascular endothelial growth factor (VEGF), epidermal growth factor receptor (EGFR) and CD133. Furthermore, SMAD4 loss causes alterations to multiple kinase pathways (particularly the phosphorylated ERK/p38/Akt pathways), and increases chemoresistance in vitro. Finally, PDAC cells with intact SMAD4 are more sensitive to TGF-β1 inhibitor treatment to reduced cell migration; PDAC cells lacking SMAD4 showed decreased cell motility in response to EGFR inhibitor treatment.

CONCLUSIONS

This study revealed the molecular basis for SMAD4-dependent differences in PDAC with the aim of identifying the subset of patients likely to respond to therapies targeting the TGF-β or EGFR signaling pathways and of identifying potential therapeutic interventions for PDAC patients with SMAD4 defects.

The role of inflammation in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with an extremely poor prognosis. Inflammatory processes have emerged as key mediators of pancreatic cancer development and progression. In genetically engineered mouse models, induction of pancreatitis accelerates PDAC development, and patients with chronic pancreatitis are known to have a higher risk of developing pancreatic cancer. In recent years, much effort has been given to identify the underlying mechanisms that contribute to inflammation-induced tumorigenesis. Many inflammatory pathways have been identified and inhibitors have been developed in order to prevent cancer development and progression. In this chapter, we discuss the role of inflammatory pathways in the initiation and progression of pancreatic cancer as well as the role of inhibitors used in treatment and prevention of pancreatic cancer.

Adeno-associated virus enhances wild-type and oncolytic adenovirus spread

The contamination of adenovirus (Ad) stocks with adeno-associated viruses (AAV) is usually unnoticed, and it has been associated with lower Ad yields upon large-scale production. During Ad propagation, AAV contamination needs to be detected routinely by polymerase chain reaction without symptomatic suspicion. In this study, we describe that the coinfection of either Ad wild type 5 or oncolytic Ad with AAV results in a large-plaque phenotype associated with an accelerated release of Ad from coinfected cells. This accelerated release was accompanied with the expected decrease in Ad yields in two out of three cell lines tested. Despite this lower Ad yield, coinfection with AAV accelerated cell death and enhanced the cytotoxicity mediated by Ad propagation. Intratumoral coinjection of Ad and AAV in two xenograft tumor models improved antitumor activity and mouse survival. Therefore, we conclude that accidental or intentional AAV coinfection has important implications for Ad-mediated virotherapy.

Concentrative nucleoside transporter 1 (hCNT1) promotes phenotypic changes relevant to tumor biology in a translocation-independent manner

Nucleoside transporters (NTs) mediate the uptake of nucleosides and nucleobases across the plasma membrane, mostly for salvage purposes. The canonical NTs belong to two gene families, SLC29 and SLC28. The former encode equilibrative nucleoside transporter proteins (ENTs), which mediate the facilitative diffusion of natural nucleosides with broad selectivity, whereas the latter encode concentrative nucleoside transporters (CNTs), which are sodium-coupled and show high affinity for substrates with variable selectivity. These proteins are expressed in most cell types, exhibiting apparent functional redundancy. This might indicate that CNTs have specific roles in the physiology of the cell beyond nucleoside salvage. Here, we addressed this possibility using adenoviral vectors to restore tumor cell expression of hCNT1 or a polymorphic variant (hCNT1S546P) lacking nucleoside translocation ability. We found that hCNT1 restoration in pancreatic cancer cells significantly altered cell-cycle progression and phosphorylation status of key signal-transducing kinases, promoted poly-(ADP-ribose) polymerase hyperactivation and cell death and reduced cell migration. Importantly, the translocation-defective transporter triggered these same effects on cell physiology. Moreover, this study also shows that restoration of hCNT1 expression is able to reduce tumor growth in a mouse model of pancreatic adenocarcinoma. These data predict a novel role for a NT protein, hCNT1, which appears to be independent of its role as mediator of nucleoside uptake by cells. Thereby, hCNT1 fits the profile of a transceptor in a substrate translocation-independent manner and is likely to be relevant to tumor biology.

Aquaporin 3 (AQP3) participates in the cytotoxic response to nucleoside-derived drugs

Background

Nucleoside analogs used in the chemotherapy of solid tumors, such as the capecitabine catabolite 5^′-deoxy-5-fluorouridine (5^′-DFUR) trigger a transcriptomic response that involves the aquaglyceroporin aquaporin 3 along with other p53-dependent genes. Here, we examined whether up-regulation of aquaporin 3 (AQP3) mRNA in cancer cells treated with 5^′-DFUR represents a collateral transcriptomic effect of the drug, or conversely, AQP3 participates in the activity of genotoxic agents.

Methods

The role of AQP3 in cell volume increase, cytotoxicity and cell cycle arrest was analyzed using loss-of-function approaches.

Results

5^′-DFUR and gemcitabine, but not cisplatin, stimulated AQP3 expression and cell volume, which was partially and significantly blocked by knockdown of AQP3. Moreover, AQP3 siRNA significantly blocked other effects of nucleoside analogs, including G₁/S cell cycle arrest, p21 and FAS up-regulation, and cell growth inhibition. Short incubations with 5-fluorouracil (5-FU) also induced AQP3 expression and increased cell volume, and the inhibition of AQP3 expression significantly blocked growth inhibition triggered by this drug. To further establish whether AQP3 induction is related to cell cycle arrest and apoptosis, cells were exposed to long incubations with escalating doses of 5-FU. AQP3 was highly up-regulated at doses associated with cell cycle arrest, whereas at doses promoting apoptosis induction of AQP3 mRNA expression was reduced.

Conclusions

Based on the results, we propose that the aquaglyceroporin AQP3 is required for cytotoxic activity of 5’-DFUR and gemcitabine in the breast cancer cell line MCF7 and the colon adenocarcinoma cell line HT29, and is implicated in cell volume increase and cell cycle arrest.

GALV expression enhances the therapeutic efficacy of an oncolytic adenovirus by inducing cell fusion and enhancing virus distribution

The limitations of the current oncolytic adenoviruses for cancer therapy include insufficient potency and poor distribution of the virus throughout the tumor mass. To address these problems, we generated an oncolytic adenovirus expressing the hyperfusogenic form of the gibbon-ape leukemia virus (GALV) envelope glycoprotein under the control of the adenovirus major late promoter. The oncolytic properties of the new fusogenic adenovirus, ICOVIR16, were analyzed both in vitro and in vivo, and compared with that of its non-fusogenic counterpart, ICOVIR15. Our results indicate that GALV expression by ICOVIR16 induced extensive syncytia formation and enhanced tumor cell killing in a variety of tumor cell types. When injected intratumorally or intravenously into mice with large pre-established melanoma or pancreatic tumors, ICOVIR16 rapidly reduced tumor burden, and in some cases, resulted in complete eradication of the tumors. Importantly, GALV expression induced tumor cell fusion in vivo and enhanced the spreading of the virus throughout the tumor. Taken together, these results indicate that GALV expression can improve the antitumoral potency of an oncolytic adenovirus and suggest that ICOVIR16 is a promising candidate for clinical evaluation in patients with cancer.

Oncolytic adenoviruses armed with thymidine kinase can be traced by PET imaging and show potent antitumoural effects by ganciclovir dosing

Replication-competent adenoviruses armed with thymidine kinase (TK) combine the concepts of virotherapy and suicide gene therapy. Moreover TK-activity can be detected by noninvasive positron emission-computed tomography (PET) imaging, what could potentially facilitate virus monitoring in vivo. Here, we report the generation of a novel oncolytic adenovirus that incorporates the Tat8-TK gene under the control of the Major Late Promoter in a highly selective backbone thus providing selectivity by targeting the retinoblastoma pathway. The selective oncolytic TK virus, termed ICOVIR5-TK-L, showed reduced potency compared to a non-selective counterpart. However the combination of ICOVIR5-TK-L with ganciclovir (GCV) induced a potent antitumoural effect similar to that of wild type adenovirus in a preclinical model of pancreatic cancer. Although the treatment with GCV provoked a reduction in the viral yield, both in vitro and in vivo, a two-cycle treatment of virus and GCV resulted in an enhanced antitumoral response that correlated with high TK-activity, based on microPET measurements. Thus, TK-expressing oncolytic adenoviruses can be traced by PET imaging providing real time information on the activity of the virus and its antitumoral potency can be optimized by GCV dosing.

A novel 3-dimensional culture system uncovers growth stimulatory actions by TGFβ in pancreatic cancer cells

Transforming Growth Factor-β (TGF-β) exerts cell type-specific and context-dependent effects. Understanding the intrinsic effects of TGF-β on cancer cells in pancreatic ductal adenocarcinoma (PDAC) is a prerequisite for rationalized clinical implementation of TGF-β targeting therapies. Since the tumor microenvironment can affect how cancer cell respond to TGF-β, we employed a novel three-dimensional (3D) culturing system to recapitulate stromal and extracellular matrix interactions. We show here that TGF-β stimulates growth of human and murine pancreatic cancer cell lines (PCCs) when embedded in a 3% collagen IV/laminin-rich gelatinous medium (Matrigel™) over a solidified layer of soft agar. Moreover, in this novel 3D model, concomitant treatment with TGF-β1 and epidermal growth factor (EGF) enhanced PCC growth to a greater extent than either growth factor alone, and conferred increased chemoresistance to cytotoxic compounds. These cooperative growth-stimulatory effects were blocked by pharmacological inhibition of TGF-β type I receptor with SB431542 or the EGF receptor with erlotinib. Co-incubation with SB431542 and erlotinib enhanced the efficacy of gemcitabine and cisplatin in PCCs and in primary cell cultures established from pancreata of genetically-engineered mouse models of PDAC. These findings suggest that concomitant inhibition of TGF-β and EGF signaling may represent an effective therapeutic strategy in PDAC, and that this 3D culturing system could be utilized to test ex vivo the therapeutic response of pancreatic tumor biopsies from PDAC patients, thereby providing a functional assay to facilitate personalized targeted therapies.

The role of Smad signaling in hematopoiesis and translational hematology

Hematopoietic stem cells (HSCs) reside in the bone marrow (BM) of adult individuals and function to produce and regenerate the entire blood and immune system over the course of an individual's lifetime. Historically, HSCs are among the most thoroughly characterized tissue-specific stem cells. Despite this, the regulation of fate options, such as self-renewal and differentiation, has remained elusive, partly because of the expansive plethora of factors and signaling cues that govern HSC behavior in vivo. In the BM, HSCs are housed in specialized niches that dovetail the behavior of HSCs with the need of the organism. The Smad-signaling pathway, which operates downstream of the transforming growth factor-β (TGF-β) superfamily of ligands, regulates a diverse set of biological processes, including proliferation, differentiation and apoptosis, in many different organ systems. Much of the function of Smad signaling in hematopoiesis has remained nebulous due to early embryonic lethality of most knockout mouse models. However, recently new data have been uncovered, suggesting that the Smad-signaling circuitry is intimately linked to HSC regulation. In this review, we bring the Smad-signaling pathway into focus, chronicling key concepts and recent advances with respect to TGF-β-superfamily signaling in normal and leukemic hematopoiesis.

Connexin-26 is a key factor mediating gemcitabine bystander effect

Gemcitabine is a nucleoside analogue with anticancer activity. Inside the cell, it is sequentially phosphorylated to generate the active drug. Phosphorylated nucleoside analogues have been shown to traffic through gap junctions. We investigated the participation of gap junctional intercellular communication (GJIC) as a possible mechanism spreading gemcitabine cytotoxicity in pancreatic tumors. Immunohistochemical analysis of pancreatic cancer biopsies revealed increased connexin 26 (Cx26) content but loss of connexins 32 (Cx32) and 43 (Cx43) expression. Cx26 abundance in neoplastic areas was confirmed by Cx26 mRNA in situ hybridization. Heterogeneity on the expression levels and the localization of Cx26, Cx32, and Cx43 were identified in pancreatic cancer cells and found to be associated with the extent of GJIC, and correlated with gemcitabine bystander cytotoxic effect. The abundance of Cx26 at the contact points in tumoral regions prompted us to study the involvement of Cx26 in the GJIC of gemcitabine toxic metabolites and their influence on the antitumoral effects of gemcitabine. Knockdown of Cx26 led to decreased GJIC and reduced gemcitabine bystander killing whereas overexpression of Cx26 triggered increased GJIC and enhanced the gemcitabine cytotoxic bystander effect. Gemcitabine treatment of mice bearing tumors, with a high GJIC capacity, resulted in a significant delay in tumor progression. Interestingly, gemcitabine administration in mice bearing tumors that overexpress Cx26 triggered a dramatic tumor regression of 50% from the initial volume. This study shows that Cx26 participates in the gap junction-mediated bystander cytoxic effect of gemcitabine and provides evidence that upregulation of Cx26 improves gemcitabine anticancer efficacy.

The use of caspase inhibitors in pulsed-field gel electrophoresis may improve the estimation of radiation-induced DNA repair and apoptosis

Background

Radiation-induced DNA double-strand break (DSB) repair can be tested by using pulsed-field gel electrophoresis (PFGE) in agarose-encapsulated cells. However, previous studies have reported that this assay is impaired by the spontaneous DNA breakage in this medium. We investigated the mechanisms of this fragmentation with the principal aim of eliminating it in order to improve the estimation of radiation-induced DNA repair.

Methods

Samples from cancer cell cultures or xenografted tumours were encapsulated in agarose plugs. The cell plugs were then irradiated, incubated to allow them to repair, and evaluated by PFGE, caspase-3, and histone H2AX activation (γH2AX). In addition, apoptosis inhibition was evaluated through chemical caspase inhibitors.

Results

We confirmed that spontaneous DNA fragmentation was associated with the process of encapsulation, regardless of whether cells were irradiated or not. This DNA fragmentation was also correlated to apoptosis activation in a fraction of the cells encapsulated in agarose, while non-apoptotic cell fraction could rejoin DNA fragments as was measured by γH2AX decrease and PFGE data. We were able to eliminate interference of apoptosis by applying specific caspase inhibitors, and improve the estimation of DNA repair, and apoptosis itself.

Conclusions

The estimation of radiation-induced DNA repair by PFGE may be improved by the use of apoptosis inhibitors. The ability to simultaneously determine DNA repair and apoptosis, which are involved in cell fate, provides new insights for using the PFGE methodology as functional assay.

E-cadherin contributes to the bystander effect of TK/GCV suicide therapy and enhances its antitumoral activity in pancreatic cancer models

The thymidine kinase/ganciclovir (TK/GCV) cancer gene therapy approach is based on inducing GCV metabolite cytotoxicity in tumor cells expressing the herpes simplex virus TK gene and exposed to GCV. A bystander effect, mediated by gap junctions, accounts for the transfer of toxic metabolites from TK-expressing cells to neighboring cells. It has been proposed that E-cadherin participates in the formation and function of such gap junctions. In this study we investigate the influence of E-cadherin on TK/GCV suicide therapy with a panel of cellular and in vivo models of pancreatic ductal adenocarcinoma. We observed a strong correlation of E-cadherin expression and the TK/GCV bystander effect, associated with the modulation of gap junction communication and connexin expression or localization. Importantly, the co-expression of TK and E-cadherin genes in the adenoviral vector AdTat8TKIE improved TK/GCV cytotoxicity and triggered a potent antitumoral effect, superior to standard AdTat8TK/GCV in MIAPaCa-2 xenografts. The increased expression of E-cadherin resulted in the reduction of the bcl-2 content. Interestingly, the knockdown of bcl-2 sensitized cells to TK/GCV. Thus, we propose that by restoring E-cadherin in pancreatic tumor cells we will improve TK/GCV therapy, both by enhancing the bystander effect and by facilitating the induction of apoptosis.

Targeting the TGF-beta1 pathway to prevent normal tissue injury after cancer therapy

With >10,000,000 cancer survivors in the U.S. alone, the late effects of cancer treatment are a significant public health issue. Over the past 15 years, much work has been done that has led to an improvement in our understanding of the molecular mechanisms underlying the development of normal tissue injury after cancer therapy. In many cases, these injuries are characterized at the histologic level by loss of parenchymal cells, excessive fibrosis, and tissue atrophy. Among the many cytokines involved in this process, transforming growth factor (TGF)-beta1 is thought to play a pivotal role. TGF-beta1 has a multitude of functions, including both promoting the formation and inhibiting the breakdown of connective tissue. It also inhibits epithelial cell proliferation. TGF-beta1 is overexpressed at sites of injury after radiation and chemotherapy. Thus, TGF-beta1 represents a logical target for molecular therapies designed to prevent or reduce normal tissue injury after cancer therapy. Herein, the evidence supporting the critical role of TGF-beta1 in the development of normal tissue injury after cancer therapy is reviewed and the results of recent research aimed at preventing normal tissue injury by targeting the TGF-beta1 pathway are presented.

Minimal RB-responsive E1A promoter modification to attain potency, selectivity, and transgene-arming capacity in oncolytic adenoviruses

Oncolytic adenoviruses are promising anticancer agents due to their ability to self-amplify at the tumor mass. However, tumor stroma imposes barriers difficult to overcome by these agents. Transgene expression is a valuable strategy to counteract these limitations and to enhance antitumor activity. For this purpose, the genetic backbone in which the transgene is inserted should be optimized to render transgene expression compatible with the adenovirus replication cycle and to keep genome size within the encapsidation size limit. In order to design a potent and selective oncolytic adenovirus that keeps intact all the viral functions with minimal increase in genome size, we inserted palindromic E2F-binding sites into the endogenous E1A promoter. The insertion of these sites controlling E1A-Δ24 results in a low systemic toxicity profile in mice. Importantly, the E2F-binding sites also increased the cytotoxicity and the systemic antitumor activity relative to wild-type adenovirus in all cancer models tested. The low toxicity and the increased potency results in improved antitumor efficacy after systemic injection and increased survival of mice carrying tumors. Furthermore, the constrained genome size of this backbone allows an efficient and potent expression of transgenes, indicating that this virus holds promise for overcoming the limitations of oncolytic adenoviral therapy.

Hyaluronidase expression by an oncolytic adenovirus enhances its intratumoral spread and suppresses tumor growth

Successful virotherapy requires efficient virus spread within tumors. We tested whether the expression of hyaluronidase, an enzyme which dissociates the extracellular matrix (ECM), could enhance the intratumoral distribution of an oncolytic adenovirus and improve its therapeutic activity. As a proof of concept, we demonstrated that intratumoral coadministration of hyaluronidase in mice-bearing tumor xenografts improves the antitumor activity of an oncolytic adenovirus. Next, we constructed a replication-competent adenovirus expressing a soluble form of the human sperm hyaluronidase (PH20) under the control of the major late promoter (MLP) (AdwtRGD-PH20). Intratumoral treatment of human melanoma xenografts with AdwtRGD-PH20 resulted in degradation of hyaluronan (HA), enhanced viral distribution, and induced tumor regression in all treated tumors. Finally, the PH20 cDNA was inserted in an oncolytic adenovirus that selectively kills pRb pathway-defective tumor cells. The antitumoral activity of the novel oncolytic adenovirus expressing PH20 (ICOVIR17) was compared to that of the parental virus ICOVIR15. ICOVIR17 showed more antitumor efficacy following intratumoral and systemic administration in mice with prestablished tumors, along with an improved spread of the virus within the tumor. Importantly, a single intravenous dose of ICOVIR17 induced tumor regression in 60% of treated tumors. These results indicate that ICOVIR17 is a promising candidate for clinical testing.

Verapamil enhances the antitumoral efficacy of oncolytic adenoviruses

The therapeutic potential of oncolytic adenoviruses is limited by the rate of adenovirus release. Based on the observation that several viruses induce cell death and progeny release by disrupting intracellular calcium homeostasis, we hypothesized that the alteration in intracellular calcium concentration induced by verapamil could improve the rate of virus release and spread, eventually enhancing the antitumoral activity of oncolytic adenoviruses. Our results indicate that verapamil substantially enhanced the release of adenovirus from a variety of cell types resulting in an improved cell-to-cell spread and cytotoxicity. Furthermore, the combination of the systemic administration of an oncolytic adenovirus (ICOVIR-5) with verapamil in vivo greatly improved its antitumoral activity in two different tumor xenograft models without affecting the selectivity of this virus. Overall, our findings indicate that verapamil provides a new, safe, and versatile way to improve the antitumoral potency of oncolytic adenoviruses in the clinical setting.

Growth factors as active participants in carcinogenesis: a perspective

Growth factors are low molecular peptides active in the stimulation of cell proliferation and in the regulation of embryonic development and cellular differentiation. Significant progress has been made in developing effective strategies to treat human malignancies with new chemical compounds based on a rationale directed against various components of signaling pathways. Many of these drugs target a growth factor receptor--for instance, in the form of monoclonal antibodies or inhibitors of tyrosine kinases, such as monoclonal antibodies against epidermal growth factor receptors used in treating certain types of breast cancer. Imatinib mesylate [Gleevec]) is an excellent example of mediators of signal transduction, such as tyrosine kinases. Growth factors proper are used to ameliorate various and sometimes fatal side effects of cytotoxic and/or myelosuppressive chemotherapy. Basic characteristics of several growth families are discussed with therapeutic modalities based on growth factor activity or, more often, inhibition of such activity.

Overexpression and interactions of interleukin-10, transforming growth factor beta, and vascular endothelial growth factor in esophageal squamous cell carcinoma

BACKGROUND

Sharing the role of immune suppression, interleukin-10 (IL-10), transforming growth factor beta (TGF-beta), and vascular endothelial growth factor (VEGF) are critical genes in several aspects of tumorigenesis. To elucidate the role of these cytokines in esophageal squamous cell carcinoma (ESCC), their relative mRNA expression in tumoral tissue compared with corresponding tumor-free tissue was evaluated.

METHODS

A total of 49 patients with histologically confirmed ESCC were included in the study prior to any therapeutic interventions. Quantitative analysis of the mRNA expression was performed by real-time reverse transcription-polymerase chain reaction and the clinicopathologic associations were assessed.

RESULTS

The mRNA of IL-10, VEGF, and TGF-beta was frequently overexpressed in 53.2%, 44.9%, and 37.5% of ESCC patients, respectively. TGF-beta was significantly co-expressed with IL-10 and with VEGF. Although VEGF was not independently associated with increased tumor size (p = 0.065), concomitant overexpression of VEGF with TGF-beta was significantly correlated with increased size of the tumor (p < 0.05).

CONCLUSIONS

Overexpression of IL-10, TGF-beta, and VEGF plays an important role in ESCC and consequently leads to the frequent event of immune evasion in ESCC. TGF-beta is concomitantly overexpressed with IL-10 and with VEGF in ESCC. A stimulatory signal from TGF-beta to VEGF is necessary for VEGF to promote tumor progression.

Dual role of Ski in pancreatic cancer cells: tumor-promoting versus metastasis-suppressive function

Ski used to be defined as an oncogene that contributes to the resistance of tumor cells to transforming growth factor-beta (TGF-beta)-induced growth arrest. As TGF-beta has a dual effect on tumor growth with both tumor-suppressing and -promoting activity depending on the stage of carcinogenesis and the cell type, the precise role of Ski in carcinogenesis remains unclear. In this study, we show that downregulation of Ski through lentivirus-mediated RNA interference decreases tumor growth both in vitro and in vivo, yet promotes cell invasiveness in vitro, and lung metastasis in vivo in the pancreatic cancer cell line SW1990, which contain wild-type Smad4 expression, and the BxPC3 cell line, which is Smad4 deficient. We also show that the downregulation of Ski increases TGF-beta-induced transcriptional activity, which is associated with increased TGF-beta-dependent Smad2/3 phosphorylation, and results in an altered expression profile of TGF-beta-inducible genes involved in metastasis, angiogenesis and cell proliferation and epithelial-mesenchymal transition. Immunohistochemical analysis of specimens from 71 patients with pancreatic adenocarcinoma showed a significant association between overexpression of Ski and decreased patient survival time (P = 0.0024). Our results suggest that Ski may act as a tumor proliferation-promoting factor or as a metastatic suppressor in human pancreatic cancer.

Sustained co-cultivation with human placenta-derived MSCs enhances ALK5/Smad3 signaling in human breast epithelial cells, leading to EMT and differentiation

The interaction between mammary epithelial cells and their surrounding microenvironment are important in the development of the mammary gland. Thus, mesenchymal stem cells (MSCs), which retain pluripotency for various mesenchymal lineages, may provide a permissive environment for the morphologic alteration and differentiation of mammary epithelial cells. To this end, we investigated whether the interactions between mammary epithelial cells and human placenta-derived MSCs (hPMSC) affect the morphology, proliferation, and differentiation of epithelial cells in a co-culture system. We show that after co-culture with hPMSCs, human mammary epithelial cell lines (MCF-10F and HEMC) underwent significant morphologic alterations and a dramatic increase in ductal-alveolar branching, which was accompanied by a decrease or loss of the epithelial marker E-cadherin and a gain of the mesenchymal markers, alpha-SMA and vimentin. MCF-10F and HEMC proliferation was also inhibited in the presence of hPMSCs, and this retardation in growth was due to cell cycle arrest. Furthermore, in MCF-10F and HMEC cells, hPMSCs induced the production of lipid droplets, milk fat globule protein, and milk protein lactoferrin, which are markers of functional mammary differentiation. We also noticed an elevation in ALK5 and phosphorylated Smad3 protein levels upon hPMSC co-culture. Strikingly, the changes in morphology, proliferation, and differentiation were reversed by treatment with ALK5 or Smad3 knockdown in MCF-10F/hPMSC co-cultures. Collectively, our findings suggest that co-cultivation with hPMSCs leads to epithelial to mesenchymal transition (EMT) and differentiation of human breast epithelial cells through the ALK5/Smad3 signaling pathway.

Low-level expression of Smad7 correlates with lymph node metastasis and poor prognosis in patients with pancreatic cancer

BACKGROUND

Whether Smad7 acts as a tumor proliferation promoting factor or as a metastatic suppressor in human pancreatic cancer remains unclear. This study aims to determine the prognostic value of Smad7 in patients with pancreatic adenocarcinoma.

METHODS

Surgical specimens obtained from 71 patients with pancreatic adenocarcinoma were immunohistochemically assessed for Smad7, Ki-67, MMP2, CD34, and Smad4 expression. The relationship between Smad7 expression and the clinicopathological characteristics of patients with pancreatic adenocarcinoma were also evaluated.

RESULTS

Fifty-one of 71 specimens (71.8%) were Smad7 positive and 20 specimens were Smad7 negative. Negative expression of Smad7 correlated with lymph node metastasis, liver metastasis after surgery, and a poor survival rate (P = 0.0004, 0.0044, and 0.0003, respectively). We also found an inverse correlation between the expression of Smad7 and MMP2 (P = 0.0189). Multivariate analysis revealed that Smad7 expression was an independent prognostic factor [hazard ratio (HR) 0.3902; 95% confidence interval (CI) 0.1839-0.8277; P = 0.0142]. Furthermore, in both Smad4-negative and Smad4-positive groups, survival of patients with Smad7-positive tumors was significantly better than those with Smad7-negative tumors (both P < 0.0001).

CONCLUSIONS

We conclude that low-level expression of Smad7 in pancreatic cancer is significantly associated with lymph node metastasis, high MMP2 expression, and poor prognosis.