TAK-ing aim at chemoresistance: The emerging role of MAP3K7 as a target for cancer therapy.

Cellular drug resistance remains the main obstacle to the clinical efficacy of cancer chemotherapy. Alterations in key pathways regulating cell cycle checkpoints, apoptosis and Epithelial to Mesenchymal Transition (EMT), such as the Mitogen-activated protein kinase (MAPK) pathway, appear to be closely associated to cancer chemoresistance. Transforming growth factor-ß (TGF-ß)- activated kinase 1 (TAK1, also known as MAP3K7) is a serine/threonine kinase in the mitogen-activated protein kinase (MAP3K) family. It represents the cellular hub to which IL1, TGF-ß and Wnt signaling pathways converge. By regulating the phosphorylation status and activities of transcription factors including Activated Protein-1 (AP-1) and nuclear factor κ-B (NF-κB), TAK1 mediates inflammatory and pro-survival responses. The interest towards the therapeutic targeting of TAK1 is due to its identification as one of the main mediators of both chemoresistance and EMT in several types of tumors, and as the possible target for a subset of treatment-refractory colon cancers exhibiting mutated KRAS or activated WNT pathways. For these reasons, many efforts have been made to design inhibitors of TAK1 kinase activity, which could be used to reverse TAK1-mediated chemoresistance. The activity of these inhibitors, in combination with the most commonly used chemotherapeutic drugs, has been tested in preclinical studies, proving the efficacy of TAK1 inhibition in reducing tumor growth and survival following chemotherapy administration. In the first part of this review, we describe the mechanisms underlying TAK1 regulation such as phosphorylation, ubiquitination and targeting by microRNAs. We then focus on the development of therapeutic small molecule inhibitors of TAK1 kinase activity, as well as preclinical studies supporting the role of TAK1 as a potential target for enhancing the response of tumors to anticancer therapies.

Pancreatic Cancer and Obesity: Molecular Mechanisms of Cell Transformation and Chemoresistance.

Cancer and obesity are the two major epidemics of the 21st century. Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of death, with a five-year overall survival rate of only 8%. Its incidence and mortality have increased in recent years, and this cancer type is expected to be among the top five leading causes of cancer-related death by 2030 in the United States (US). In the last three decades, the prevalence of overweight people has boosted with a consequent increase in obesity-related diseases. Considerable epidemiologic evidence correlates overweight and obese conditions to an increased risk of several types of cancer, including PDAC. Besides being a risk factor for multiple metabolic disorders, the tumor-promoting effects of obesity occur at the local level via inflammatory mediators that are associated with adipose inflammation and metabolic or hormones mediators and microbiota dysbiosis. Although an excess of body mass index (BMI) represents the second most modifiable risk factor for PDAC with an increased cancer related-death of more than 20⁻40%, still little is known about the molecular mechanisms that underlie this strong association. In this review, we focused on the role of obesity as a preventable risk factor of PDAC, discussing the molecular mechanisms linking obesity to cancer initiation and progression. Moreover, we highlighted the role of obesity in defining chemoresistance, showing how a high BMI can actually reduce response to chemotherapy.

Angiopoietin-Like Proteins in Angiogenesis, Inflammation and Cancer.

Altered expression of secreted factors by tumor cells or cells of the tumor microenvironment is a key event in cancer development and progression. In the last decade, emerging evidences supported the autocrine and paracrine activity of the members of the Angiopoietin-like (ANGPTL) protein family in angiogenesis, inflammation and in the regulation of different steps of carcinogenesis and metastasis development. Thus, ANGPTL proteins become attractive either as prognostic or predictive biomarkers, or as novel target for cancer treatment. Here, we outline the current knowledge about the functions of the ANGPTL proteins in angiogenesis, cancer progression and metastasis. Moreover, we discuss the most recent evidences sustaining their role as prognostic or predictive biomarkers for cancer therapy. Although the role of ANGPTL proteins in cancer has not been fully elucidated, increasing evidence suggest their key effects in the proliferative and invasive properties of cancer cells. Moreover, given the common overexpression of ANGPTL proteins in several aggressive solid tumors, and their role in tumor cells and cells of the tumor microenvironment, the field of research about ANGPTL proteins network may highlight new potential targets for the development of future therapeutic strategies.

Transcriptional regulation by mutant p53 and oncogenesis.

More than half of all human cancers carry p53 gene mutations whose resulting proteins are mostly full-length with a single amino acid change, abundantly present in cancer cells and unable to exert oncosuppressor activities. Frequently, mutant p53 proteins gain oncogenic functions through which they actively contribute to the establishment, the maintenance and the spreading of a given cancer cell. Intense research effort has been devoted to the deciphering of the molecular mechanisms underlying the gain of function of mutant p53 proteins. Here we mainly review the oncogenic transcriptional activity of mutant p53 proteins that mainly occurs through the aberrant cooperation with bona-fide transcription factors and leads to either aberrant up-regulation or down-regulation of selected target genes. Thus, mutant p53 proteins are critical components of oncogenic transcriptional networks that have a profound impact in human cancers.

Exemestane blocks mesothelioma growth through downregulation of cAMP, pCREB and CD44 implicating new treatment option in patients affected by this disease.

BACKGROUND: Recent evidence suggests that aromatase may be involved in the pathogenesis of malignant mesothelioma. Here, we evaluated the effect of exemestane, an inhibitor of aromatase, in the treatment of mesothelioma using in vitro and in vivo preclinical models. RESULTS: We show a significant reduction of cell proliferation, survival, migration and block of cells in S phase of cell cycle in mesothelioma cells upon exemestane treatment. Moreover, we find that CD44, which is involved in mesothelioma cells migration, was modulated by exemestane via cAMP and pCREB. Most importantly, in mice mesothelioma xenograft exemestane causes a significant decrease in tumor size and the association pemetrexed/exemestane is more effective than pemetrexed/cisplatin. CONCLUSION: The preclinical mesothelioma model suggests that exemestane might be beneficial in mesothelioma treatment.

Blockage of melatonin receptors impairs p53-mediated prevention of DNA damage accumulation.

Melatonin has been known to be a chemopreventive agent since its levels inversely correlate with the risk of developing cancer. We have recently shown that melatonin induces p38-dependent phosphorylation of both p53 and histone H2AX. This is associated with a p53-mediated increase in repair of both endogenous and chemotherapy-induced DNA damage. In addition, the inhibition of p38 activities impairs melatonin's capability to induce a p53-dependent DNA damage response and thus its ability to maintain genome integrity. Since melatonin-induced p53 phosphorylation requires an intact p38 phosphorylation cascade and p38 can be activated by G proteins, we supposed that melatonin's activities could be mediated by its G-protein-coupled membrane receptors, MT1 and MT2. Here, we show that the activation of the p53-dependent DNA damage response by melatonin is indeed mediated by MT1 and MT2. As a result, the absence of either receptor impairs melatonin's ability to reduce both cell proliferation and clonogenic potential of cancer cells. In addition, this causes an impairment of the p53-dependent DNA damage response. By providing molecular insight, our findings might have translational impact, suggesting the involvement of melatonin receptors in tumorigenesis.

Plasma IL8 Is a Biomarker for TAK1 Activation and Predicts Resistance to Nanoliposomal Irinotecan in Patients with Gemcitabine-Refractory Pancreatic Cancer.

PURPOSE: Pancreatic cancer is one of the most lethal solid tumors, mainly because of its intrinsic chemoresistance. We identified TAK1 as a central hub sustaining this resistance. Nanoliposomal irinotecan (nal-IRI) is a novel treatment for metastatic gemcitabine-refractory pancreatic cancer. We endeavored to identify circulating markers for TAK1 activation predicting chemoresistance in this setting. EXPERIMENTAL DESIGN: In vivo activity of nal-IRI was validated in an orthotopic nude murine model expressing TAK1-specific shRNA. Plasma concentration of 20 different cytokines were measured by a multiplex xMAP/Luminex technology in patients prospectively enrolled to receive nal-IRI plus 5-fluorouracil/leucovorin (5-FU/LV). The optimal cutoff thresholds able to significantly predict patients' outcome were obtained on the basis of the maximization of the Youden's statistics. RESULTS: Differential expression profiling revealed the gene coding for IL8 as the most significantly downregulated in shTAK1 pancreatic cancer cell lines. Mice bearing shTAK1 tumors had significantly lower plasma levels of IL8 and experienced a significant reduction in tumor growth if treated with nal-IRI, whereas those bearing TAK1-proficient tumors were resistant to this agent. In a discovery cohort of 77 patients, IL8 was the circulating factor most significantly correlated with survival (plasma levels lower vs higher than cutoff: mPFS 3.4 months vs 2.8 months; hazard ratio [HR], 2.55; 95% CI, 1.39-4.67; P = 0.0017; median overall survival 8.9 months vs 5.3 months; HR, 3.51; 95% CI, 0.84-6.68; P = 4.9e-05). These results were confirmed in a validation cohort of 50 patients. CONCLUSIONS: Our study identified IL8 as the most significant circulating factor for TAK1 pathway activation and candidates IL8 as a potential predictive biomarker of resistance to nal-IRI in gemcitabine-refractory patients with pancreatic cancer.

From Genetic Alterations to Tumor Microenvironment: The Ariadne's String in Pancreatic Cancer.

The threatening notoriety of pancreatic cancer mainly arises from its negligible early diagnosis, highly aggressive progression, failure of conventional therapeutic options and consequent very poor prognosis. The most important driver genes of pancreatic cancer are the oncogene KRAS and the tumor suppressors TP53, CDKN2A, and SMAD4. Although the presence of few drivers, several signaling pathways are involved in the oncogenesis of this cancer type, some of them with promising targets for precision oncology. Pancreatic cancer is recognized as one of immunosuppressive phenotype cancer: it is characterized by a fibrotic-desmoplastic stroma, in which there is an intensive cross-talk between several cellular (e.g., fibroblasts, myeloid cells, lymphocytes, endothelial, and myeloid cells) and acellular (collagen, fibronectin, and soluble factors) components. In this review; we aim to describe the current knowledge of the genetic/biological landscape of pancreatic cancer and the composition of its tumor microenvironment; in order to better direct in the intrinsic labyrinth of this complex tumor type. Indeed; disentangling the genetic and molecular characteristics of cancer cells and the environment in which they evolve may represent the crucial step towards more effective therapeutic strategies.

Modulating TAK1 Expression Inhibits YAP and TAZ Oncogenic Functions in Pancreatic Cancer.

YAP and TAZ are central determinants of malignancy; however, their functions remain still undruggable. We identified TGFß-activated kinase 1 (TAK1) as a central hub integrating the most relevant signals sustaining pancreatic cancer aggressiveness and chemoresistance. Glycogen synthase kinase (GSK)3 is known to stabilize TAK1, and its inhibition causes a reduction in TAK1 levels. Here, we hypothesized that TAK1 could sustain YAP/TAZ program, and thus, modulation of TAK1 expression through the inhibition of GSK3 could impair YAP/TAZ functions in pancreatic cancer.Differentially expressed transcripts between pancreatic cancer cells expressing scramble or TAK1-specific shRNA were annotated for functional interrelatedness by ingenuity pathway analysis. TAK1 expression was modulated by using different GSK3 inhibitors, including LY2090314. In vivo activity of LY2090314 alone or in combination with nab-paclitaxel was evaluated in an orthotopic nude mouse model.Differential gene expression profiling revealed significant association of TAK1 expression with HIPPO and ubiquitination pathways. We measured a significant downregulation of YAP/TAZ and their regulated genes in shTAK1 cells. TAK1 prevented YAP/TAZ proteasomal degradation in a kinase independent manner, through a complex with TRAF6, thereby fostering their K63-ubiquitination versus K48-ubiquitination. Pharmacologic modulation of TAK1 by using GSK3 inhibitors significantly decreased YAP/TAZ levels and suppressed their target genes and oncogenic functions. In vivo, LY2090314 plus nab-paclitaxel significantly prolonged mice survival duration.Our study demonstrates a unique role for TAK1 in controlling YAP/TAZ in pancreatic cancer. LY2090314 is a novel agent that warrants further clinical development in combination with nab-paclitaxel for the treatment of pancreatic cancer.

A phase II trial of the FGFR inhibitor pemigatinib in patients with metastatic esophageal-gastric junction/gastric cancer trastuzumab resistant: the FiGhTeR trial.

BACKGROUND: Prognosis of patients affected by metastatic esophageal-gastric junction (EGJ) or gastric cancer (GC) remains dismal. Trastuzumab, an anti-HER2 monoclonal antibody, is the only targeted agent approved for the first-line treatment of patients with HER2-overexpressing advanced EGJ or GC in combination with chemotherapy. However, patients invariably become resistant during this treatment. We recently identified the overexpression of fibroblast growth factor (FGF) receptor 3 (FGFR3) as a molecular mechanism responsible for trastuzumab resistance in GC models, providing the rationale for the inhibition of this receptor as a potential second-line strategy in this disease. Pemigatinib is a selective, potent, oral inhibitor of FGFR1, 2, and 3. METHODS: The FiGhTeR trial is a phase II, single-arm, open-label study to assess safety and activity of the FGFR inhibitor pemigatinib as second-line treatment strategy in metastatic EGJ/GC patients progressing under trastuzumab-containing therapies. The primary endpoint is the 12-week progression-free survival rate. Plasma and tumor tissue samples will be collected for translational research analyses at baseline, during treatment, and at progression on pemigatinib. DISCUSSION: Co-alterations in genes coding for different tyrosine-kinase receptors are emerging as relevant mechanisms of acquired resistance to anti-HER2 therapeutic strategies in GC. In particular, our group has recently identified that in GC models the overexpression of FGFR3 sustains the acquired resistance to trastuzumab. This trial aims to assess the safety, tolerability and activity of the FGFR inhibitor pemigatinib as a second-line treatment in metastatic EGJ/GC patients refractory to first-line trastuzumab-containing therapies. Furthermore, this study offers the opportunity to prospectively study mechanisms and pathways involved in trastuzumab resistance. PROTOCOL NUMBER: CRC2017_02. EUDRACT NUMBER: 2017-004522-14.

Novel Biomarkers for Prediction of Response to Preoperative Systemic Therapies in Gastric Cancer.

Preoperative chemo- and radiotherapeutic strategies followed by surgery are currently a standard approach for treating locally advanced gastric and esophagogastric junction cancer in Western countries. However, in a large number of cases, the tumor is extremely resistant to these treatments and the patients are exposed to unnecessary toxicity and delayed surgical therapy. The current clinical trials evaluating the combination of preoperative systemic therapies with modern targeted and immunotherapeutic agents represent a unique opportunity for identifying predictive biomarkers of response to select patients that would benefit the most from these treatments. However, it is of utmost importance that these potential biomarkers are corroborated by extensive preclinical and translational research. The aim of this review article is to present the most promising biomarkers of response to classic chemotherapeutic, anti-HER2, antiangiogenic, and immunotherapeutic agents that can be potentially useful for personalized preoperative systemic therapies in gastric cancer patients.

Predictive biomarkers for the treatment of resectable esophageal and esophago-gastric junction adenocarcinoma: from hypothesis generation to clinical validation.

INTRODUCTION: Esophageal and esophago-gastric junction (EGJ) adenocarcinomas remain a major health problem worldwide with a worryingly increasing incidence. Recent trials indicate survivals benefit for preoperative or perioperative chemoradiotherapy compared to surgery alone. Beside standard chemoradiotherapy regimens, new therapeutic approaches with targeted therapies have been proposed for the treatment of resectable disease. However, clinical outcomes remain extremely poor due to drug resistance phenomena. The failure of these approaches could be partially ascribed to their incorrect application in patients. Therefore, the identification of strong biomarkers for optimal patient management is urgently needed. Areas covered: This review aims to summarize and critically discuss the most relevant findings regarding predictive biomarker development for neoadjuvant treatment of resectable esophageal and esophago-gastric junction adenocarcinoma patients. Expert commentary: Optimizing the currently available therapeutic modalities through a more accurate selection of patients may avoid the use of ineffective and potentially toxic treatments. During the last decade, the advent of high-throughput '-omics' technologies has set the basis for a new biomarker discovery approach from 'molecule by molecule' screening towards a large-scale systematic screening process with exponential increases in putative biomarkers, which often failed to provide adequate clinical validation.

MEKK3 Sustains EMT and Stemness in Pancreatic Cancer by Regulating YAP and TAZ Transcriptional Activity.

BACKGROUND/AIM: Pancreatic cancer is one of the most threatening and poorly understood human malignancies. MEKK3 (MAP3K3) is a serine/threonine kinase activated by different signaling pathways. YAP and TAZ are critical oncogenic effectors in pancreatic cancer. We hypothesized that MEKK3 could sustain pancreatic cancer by inducing YAP/TAZ oncogenic activities. MATERIALS AND METHODS: In Panc1 and AsPC1 pancreatic cancer cell lines MEKK3 was knocked-out (KO) by the CRISPR/Cas9 method. These cells were used to evaluate MEKK3 contribution to the expression of YAP/TAZ and their target genes, cell migration, stemness, and in vivo tumor growth. RESULTS: MEKK3 KO reduced both EMT and cell migration, the size of 3D colonies and the percentage of CD44+/CD24+/EpCAM+ CSC, promoter recruitment of YAP/TAZ and the expression of their target genes. It reduced tumor growth and prolonged mice overall survival. CONCLUSION: Silencing of MEKK3 represents a valid approach to revert in vivo the aggressiveness of pancreatic cancer by modulating YAP/TAZ transcriptional activities.

Inhibition of p63 transcriptional activity by p14ARF: functional and physical link between human ARF tumor suppressor and a member of the p53 family.

The ARF/MDM2/p53 pathway is a principal defense mechanism to protect the organism from uncontrolled effects of deregulated oncogenes. Oncogenes activate ARF, which interacts with and inhibits the ubiquitin ligase MDM2, resulting in p53 stabilization and activation. Once stabilized and activated, p53 can either induce or repress a wide array of different gene targets, which in turn can regulate cell cycle, DNA repair, and a number of apoptosis-related genes. Here we show that, unlike p53, p63, a member of the p53 family, directly interacts with p14(ARF). Through this interaction ARF inhibits p63-mediated transactivation and transrepression. In p63-transfected cells, ARF, which normally localizes into nucleoli, accumulates in the nucleoplasm. Based on these observations, we suggest that stimuli inducing p14(ARF) expression can, at the same time, activate p53 and impair p63 transcriptional activity, altering the pattern of p53 target gene expression. Here we show, for the first time, a physical and functional link between the p14(ARF) tumor suppressor protein and p63, a member of the p53 family.

A circulating TH2 cytokines profile predicts survival in patients with resectable pancreatic adenocarcinoma.

Surgery is the only potentially curative option for patients with pancreatic ductal adenocarcinoma (PDAC), but metastatic relapse remains common. We hypothesized that the expression levels of inflammatory cytokines could predict recurrence of PDAC, thus allowing to select patients who most likely could benefit from surgical resection. We prospectively collected plasma at diagnosis from 287 patients with pancreatic resectable neoplasms. The expression levels of 23 cytokines were measured in 90 patients with PDAC by using a multiplex analyte profiling assay. Levels higher than cutoff identified of the TH2 cytokines interleukin (IL)4, IL5, IL6 of macrophage inflammatory protein (MIP)1α, granulocyte-macrophage colony-stimulating factor (GM-CSF), and monocyte chemoattractant protein (MCP)1, and of IL17α, IFNγ-induced protein (IP)10, and IL1b were significantly associated with a shorter median OS. In particular, levels of IL4 and IP10 higher than cutoff identified, and level of TH1 cytokines TNFα and INFγ, and of IL9 and IL1Rα lower than cutoff identified were significantly associated with a shorter DFS. In the multivariate analysis, high IP10 was confirmed as negatively associated with OS (HR = 3.097, p = 0.014) and IL4 and TNFα remain negatively (HR = 2.75, p = 0.002) and positively (HR = 0.224, p = 0.049) associated with DFS, respectively. Simultaneous expression of low IL4 and high TNFα identified patients with best prognosis (HR = 0.313, p < 0.0001). In conclusion, we demonstrated that, among a series of cytokines, IL4 is the most significant independent prognostic factor for DFS in resectable PDAC patients, and it could be useful to select patients with high risk of early recurrence who may avoid an unnecessary resection.

Homeobox B9 Mediates Resistance to Anti-VEGF Therapy in Colorectal Cancer Patients.

Purpose: The identification of predictive biomarkers for antiangiogenic therapies remains an unmeet need. We hypothesized that the transcription factor Homeobox B9 (HOXB9) could be responsible for the tumor resistance to the anti-VEGF agent bevacizumab.Experimental Design: HOXB9 expression and activation were measured in eight models of colorectal and pancreatic cancer with different resistance to bevacizumab. Serum levels of Angiopoietin-like Protein (Angptl)2, CXC receptor ligand (CXCL)1, IL8, and TGFß1 in tumor-bearing mice were measured by multiplex xMAP technology. HOXB9 expression was measured by immunohistochemical analysis in 81 pretreatment specimens from metastatic colorectal cancer patients. Differences in progression-free survival (PFS) were determined using a log-rank test.Results: HOXB9-positive tumors were resistant to bevacizumab, whereas mice bearing HOXB9-negative tumors were cured by this agent. Silencing HOXB9 in bevacizumab-resistant models significantly (P < 0.05) reduced Angptl2, CXCL1, IL8, and TGFß1 levels, reverted their mesenchymal phenotype, reduced CD11b+ cells infiltration, and restored, in turn, sensitivity to bevacizumab. HOXB9 had no prognostic value in patients treated with a first-line chemotherapeutic regimen noncontaining bevacizumab. However, patients affected by an HOXB9-negative tumor had a significantly longer PFS compared with those with an HOXB9-positive tumor if treated with a first-line regimen containing bevacizumab (18.0 months vs. 10.4 months; HR 2.037; 95% confidence interval, 1.006-4.125; P = 0.048).Conclusions: These findings integrate the complexity of numerous mechanisms of anti-VEGF resistance into the single transcription factor HOXB9. Silencing HOXB9 could be a promising approach to modulate this resistance. Our results candidate HOXB9 as predictive biomarker for selecting colorectal cancer patients for antiangiogenic therapy. Clin Cancer Res; 23(15); 4312-22. ©2017 AACR.

Comet Assay in Cancer Chemoprevention.

The comet assay can be useful in monitoring DNA damage in single cells caused by exposure to genotoxic agents, such as those causing air, water, and soil pollution (e.g., pesticides, dioxins, electromagnetic fields) and chemo- and radiotherapy in cancer patients, or in the assessment of genoprotective effects of chemopreventive molecules. Therefore, it has particular importance in the fields of pharmacology and toxicology, and in both environmental and human biomonitoring. It allows the detection of single strand breaks as well as double-strand breaks and can be used in both normal and cancer cells. Here we describe the alkali method for comet assay, which allows to detect both single- and double-strand DNA breaks.

Multitargeting activity of miR-24 inhibits long-term melatonin anticancer effects.

We have previously shown that melatonin exerts tumor suppressor activities by inducing the p38-p53 axis. This occurred within a few hours while no data are available on how melatonin pathway can be sustained on the long term. Here we show that miR-24, which has been demonstrated to target genes involved in the DNA repair process, targets p38, p53, PML and H2AX simultaneously. We show that long-term treatment with melatonin can decrease miR-24 levels post-transcriptionally, which pairs with a long-wave regulation of genes involved in cell proliferation, DNA damage, RNA metabolism and cell shape and transformation. Moreover, we show that melatonin can inhibit cell proliferation and migration, at least in part, by downregulating miR-24. Furthermore, we propose the involvement of hnRNP A1, which is downregulated by melatonin and involved in miRNA processing, in the regulation of miR-24 levels by melatonin. We conclude showing that miR-24 is upregulated in colon, breast and head and neck datasets and its levels negatively correlate with overall survival.