Inflammation-mediated genetic and epigenetic alterations drive cancer development in the neighboring epithelium upon stromal abrogation of TGF-β signaling

TGF-β signaling in health, disease, and therapeutics

Transforming growth factor (TGF)-β is a multifunctional cytokine expressed by almost every tissue and cell type. The signal transduction of TGF-β can stimulate diverse cellular responses and is particularly critical to embryonic development, wound healing, tissue homeostasis, and immune homeostasis in health. The dysfunction of TGF-β can play key roles in many diseases, and numerous targeted therapies have been developed to rectify its pathogenic activity. In the past decades, a large number of studies on TGF-β signaling have been carried out, covering a broad spectrum of topics in health, disease, and therapeutics. Thus, a comprehensive overview of TGF-β signaling is required for a general picture of the studies in this field. In this review, we retrace the research history of TGF-β and introduce the molecular mechanisms regarding its biosynthesis, activation, and signal transduction. We also provide deep insights into the functions of TGF-β signaling in physiological conditions as well as in pathological processes. TGF-β-targeting therapies which have brought fresh hope to the treatment of relevant diseases are highlighted. Through the summary of previous knowledge and recent updates, this review aims to provide a systematic understanding of TGF-β signaling and to attract more attention and interest to this research area.

Skin aging from the perspective of dermal fibroblasts: the interplay between the adaptation to the extracellular matrix microenvironment and cell autonomous processes

This article summarizes important molecular mechanisms that drive aging in human skin from the perspective of dermal fibroblasts. The dermis comprises the bulk of the skin and is largely composed of a collagen-rich extracellular matrix (ECM). The dermal ECM provides mechanical strength, resiliency, and an environment that supports the functions of ibroblasts and other types of dermal cells. Fibroblasts produce the dermal ECM and maintain its homeostasis. Fibroblasts attach to the ECM and this attachment controls their morphology and function. During aging, the ECM undergoes gradual degradation that is nitiated by matrix metalloproteinases (MMPs). This degradation alters mechanical forces within the dermal ECM and disrupts he interactions between fibroblasts and the ECM thereby generating an aged fibroblast phenotype. This aged fibroblast phenotype is characterized by collapsed morphology, altered mechanosignaling, induction of CCN1, and activation of transcription factor AP-1, with consequent upregulation of target genes including MMPs and pro-inflammatory mediators. The TGF-beta pathway coordinately regulates ECM production and turnover. Altered mechanical forces, due to ECM fragmentation, down-regulate the type II TGF-beta receptor, thereby reducing ECM production and further increasing ECM breakdown. Thus, dermal aging involves a feed-forward process that reinforces the aged dermal fibroblast phenotype and promotes age-related dermal ECM deterioration. As discussed in the article, the expression of the aged dermal fibroblast phenotype involves both adaptive and cell-autonomous mechanisms.

TGFβ control of immune responses in cancer: a holistic immuno-oncology perspective

The immune system responds to cancer in two main ways. First, there are prewired responses involving myeloid cells, innate lymphocytes and innate-like adaptive lymphocytes that either reside in premalignant tissues or migrate directly to tumours, and second, there are antigen priming-dependent responses, in which adaptive lymphocytes are primed in secondary lymphoid organs before homing to tumours. Transforming growth factor-β (TGFβ) - one of the most potent and pleiotropic regulatory cytokines - controls almost every stage of the tumour-elicited immune response, from leukocyte development in primary lymphoid organs to their priming in secondary lymphoid organs and their effector functions in the tumour itself. The complexity of TGFβ-regulated immune cell circuitries, as well as the contextual roles of TGFβ signalling in cancer cells and tumour stromal cells, necessitates the use of rigorous experimental systems that closely recapitulate human cancer, such as autochthonous tumour models, to uncover the underlying immunobiology. The diverse functions of TGFβ in healthy tissues further complicate the search for effective and safe cancer therapeutics targeting the TGFβ pathway. Here we discuss the contextual complexity of TGFβ signalling in tumour-elicited immune responses and explain how understanding this may guide the development of mechanism-based cancer immunotherapy.

C-Reactive Protein as Predictive Biomarker for Response to Chemoradiotherapy in Patients with Locally Advanced Rectal Cancer: A Retrospective Study

The standard of care for the treatment of locally advanced rectal cancer is neoadjuvant chemoradiotherapy (nCRT) followed by surgery, but complete response rates are reduced. To find predictive biomarkers of response to therapy, we conducted a retrospective study evaluating blood biomarkers before nCRT. Hemoglobin (Hg), C-reactive protein (CRP), platelets, carcinoembryonic antigen, carbohydrate antigen 19.9 levels, and neutrophil/lymphocyte ratio were obtained from 171 rectal cancer patients before nCRT. Patients were classified as responders (Ryan 0-1; ycT0N0), 59.6% (n = 102), or nonresponders (Ryan 2-3), 40.3% (n = 69), in accordance with the Ryan classification. A logistic regression using prognostic pretreatment factors identified CRP ≤ 3.5 (OR = 0.05; 95%CI: 0.01-0.21) as a strong independent predictor of response to treatment. Multivariate analysis showed that CRP was an independent predictor of disease-free survival (DFS) (HR = 5.48; 95%CI: 1.54-19.48) and overall survival (HR = 6.10; 95%CI 1.27-29.33) in patients treated with nCRT. Platelets were an independent predictor of DFS (HR = 3.068; 95%CI: 1.29-7.30) and OS (HR= 4.65; 95%CI: 1.66-13.05) and Hg was revealed to be an independent predictor of DFS (HR = 0.37; 95%CI: 0.15-0.90) in rectal cancer patients treated with nCRT. The lower expression of CRP is independently associated with an improved response to nCRT, DFS, and OS.

Overcoming TGFβ-mediated immune evasion in cancer

Transforming growth factor-β (TGFβ) signalling controls multiple cell fate decisions during development and tissue homeostasis; hence, dysregulation of this pathway can drive several diseases, including cancer. Here we discuss the influence that TGFβ exerts on the composition and behaviour of different cell populations present in the tumour immune microenvironment, and the context-dependent functions of this cytokine in suppressing or promoting cancer. During homeostasis, TGFβ controls inflammatory responses triggered by exposure to the outside milieu in barrier tissues. Lack of TGFβ exacerbates inflammation, leading to tissue damage and cellular transformation. In contrast, as tumours progress, they leverage TGFβ to drive an unrestrained wound-healing programme in cancer-associated fibroblasts, as well as to suppress the adaptive immune system and the innate immune system. In consonance with this key role in reprogramming the tumour microenvironment, emerging data demonstrate that TGFβ-inhibitory therapies can restore cancer immunity. Indeed, this approach can synergize with other immunotherapies - including immune checkpoint blockade - to unleash robust antitumour immune responses in preclinical cancer models. Despite initial challenges in clinical translation, these findings have sparked the development of multiple therapeutic strategies that inhibit the TGFβ pathway, many of which are currently in clinical evaluation.

Transforming Growth Factor-β: An Agent of Change in the Tumor Microenvironment

Transforming Growth Factor-β (TGF-β) is a key regulator of embryonic development, adult tissue homeostasis, and lesion repair. In tumors, TGF-β is a potent inhibitor of early stage tumorigenesis and promotes late stage tumor progression and metastasis. Here, we review the roles of TGF-β as well as components of its signaling pathways in tumorigenesis. We will discuss how a core property of TGF-β, namely its ability to change cell differentiation, leads to the transition of epithelial cells, endothelial cells and fibroblasts to a myofibroblastoid phenotype, changes differentiation and polarization of immune cells, and induces metabolic reprogramming of cells, all of which contribute to the progression of epithelial tumors.

Can Pre-Treatment Inflammatory Parameters Predict the Probability of Sphincter-Preserving Surgery in Patients with Locally Advanced Low-Lying Rectal Cancer?

There is evidence suggesting that pre-treatment clinical parameters can predict the probability of sphincter-preserving surgery in rectal cancer; however, to date, data on the predictive role of inflammatory parameters on the sphincter-preservation rate are not available. The aim of the present cohort study was to investigate the association between inflammation-based parameters and the sphincter-preserving surgery rate in patients with low-lying locally advanced rectal cancer (LARC). A total of 848 patients with LARC undergoing radiotherapy from 2004 to 2019 were retrospectively reviewed in order to identify patients with rectal cancer localized ≤6 cm from the anal verge, treated with neo-adjuvant radiochemotherapy (nRCT) and subsequent surgery. Univariable and multivariable analyses were used to investigate the role of pre-treatment inflammatory parameters, including the C-reactive protein (CRP), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR) for the prediction of sphincter preservation. A total of 363 patients met the inclusion criteria; among them, 210 patients (57.9%) underwent sphincter-preserving surgery, and in 153 patients (42.1%), an abdominoperineal rectum resection was performed. Univariable analysis showed a significant association of the pre-treatment CRP value (OR = 2.548, 95% CI: 1.584–4.097, p < 0.001) with sphincter preservation, whereas the pre-treatment NLR (OR = 1.098, 95% CI: 0.976–1.235, p = 0.120) and PLR (OR = 1.002, 95% CI: 1.000–1.005, p = 0.062) were not significantly associated with the type of surgery. In multivariable analysis, the pre-treatment CRP value (OR = 2.544; 95% CI: 1.314–4.926; p = 0.006) was identified as an independent predictive factor for sphincter-preserving surgery. The findings of the present study suggest that the pre-treatment CRP value represents an independent parameter predicting the probability of sphincter-preserving surgery in patients with low-lying LARC.

Roles of TGF-β signaling pathway in tumor microenvirionment and cancer therapy

Transforming growth factor β (TGF- β) signaling pathway has pleiotropic effects on cell proliferation, differentiation, adhesion, senescence, and apoptosis. TGF-β can be widely produced by various immune or non-immune cells and regulate cell behaviors through autocrine and paracrine. It plays essential roles in biological processes including embryological development, immune response, and tumor progression. Few cell signalings can contribute to so many pleiotropic functions as the TGF- β signaling pathway in mammals. The significant function of TGF-β signaling in tumor progression and evasion leading it to draw great attention in scientific and clinical research. Understanding the mechanism of TGF- β signaling provides us with chances to potentiate the effectiveness and selectivity of this therapeutic method. Herein, we review the molecular and cellular mechanisms of TGF-β signaling in carcinomas and tumor microenvironment. Then, we enumerate main achievements of TGF-β blockades used or being evaluated in cancer therapy, providing us opportunities to improve therapeutical approaches in the tumor which thrive in a TGF-β-rich environment.

The Elevated Pre-Treatment C-Reactive Protein Predicts Poor Prognosis in Patients with Locally Advanced Rectal Cancer Treated with Neo-Adjuvant Radiochemotherapy

The aim of the present study was to investigate the association of the pre-treatment C-reactive protein (CRP) plasma level with survival outcomes in a cohort of 423 consecutive patients with locally advanced rectal cancer treated with neo-adjuvant radiochemotherapy followed by surgical resection. To evaluate the prognostic value of the CRP level for clinical endpoints recurrence-free survival (RFS), local-regional control (LC), metastases-free survival (MFS), and overall survival (OS), uni- and multivariate Cox regression analyses were applied, and survival rates were calculated using Kaplan–Meier analysis. The median follow-up time was 73 months. In univariate analyses, the pre-treatment CRP level was a significant predictor of RFS (hazard ratio (HR) 1.015, 95% CI 1.006–1.023; p < 0.001), LC (HR 1.015, 95% CI 1.004–1.027; p = 0.009), MFS (HR 1.014, 95% CI 1.004–1.023; p = 0.004), and OS (HR 1.016, 95% CI 1.007–1.024; p < 0.001). Additionally, univariate analysis identified the MRI circumferential resection margin (mrCRM) and pre-treatment carcinoembryonic antigen (CEA) as significant predictor of RFS (HR 2.082, 95% CI 1.106–3.919; p = 0.023 and HR 1.005, 95% CI 1.002–1.008; p < 0.001). Univariate analysis also revealed a significant association of the mrCRM (HR 2.089, 95% CI 1.052–4.147; p = 0.035) and CEA (HR 1.006, 95% CI 1.003–1.008; p < 0.001) with MFS. Age and CEA were prognostic factors for OS (HR 1.039, 95% CI 1.013–1.066; p = 0.003 and HR 1.005, 95% CI 1.002–1.008; p < 0.001). In multivariate analysis that included parameters with a p-level < 0.20 in univariate analysis, the pre-treatment CRP remained a significant prognostic factor for RFS (HR 1.013, 95%CI 1.001–1.025; p = 0.036), LC (HR 1.014, 95% CI 1.001–1.027; p = 0.031), and MFS (HR 1.013, 95% CI 1.000–1.027; p = 0.046). The results support the hypothesis that an elevated pre-treatment CRP level is a predictor of poor outcome. If confirmed by additional studies, this easily measurable biomarker could contribute to the identification of patients who might be candidates for more aggressive local or systemic treatment approaches or the administration of anti-inflammatory drugs.

Dualism of FGF and TGF-β Signaling in Heterogeneous Cancer-Associated Fibroblast Activation with ETV1 as a Critical Determinant

Heterogeneity of cancer-associated fibroblasts (CAFs) can result from activation of distinct signaling pathways. We show that in primary human dermal fibroblasts (HDFs), fibroblast growth factor (FGF) and transforming growth factor β (TGF-β) signaling oppositely modulate multiple CAF effector genes. Genetic abrogation or pharmacological inhibition of either pathway results in induction of genes responsive to the other, with the ETV1 transcription factor mediating the FGF effects. Duality of FGF/TGF-β signaling and differential ETV1 expression occur in multiple CAF strains and fibroblasts of desmoplastic versus non-desmoplastic skin squamous cell carcinomas (SCCs). Functionally, HDFs with opposite TGF-β versus FGF modulation converge on promoting cancer cell proliferation. However, HDFs with increased TGF-β signaling enhance invasive properties and epithelial-mesenchymal transition (EMT) of SCC cells, whereas HDFs with increased FGF signaling promote macrophage infiltration. The findings point to a duality of FGF versus TGF-β signaling in distinct CAF populations that promote cancer development through modulation of different processes.

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FGF and TGF-β signaling exert opposite control over multiple CAF effector genes

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ETV1 transcription factor mediates FGF effects and suppresses those of TGF-β

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Modulation of either pathway leads to different tumor-promoting CAF populations

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TGF-β-activated CAFs promote EMT, but FGF-activated CAFs increase inflammation

Dermal Fibroblast CCN1 Expression in Mice Recapitulates Human Skin Dermal Aging

The aging process deleteriously alters the structure and function of dermal collagen. These alterations result in thinning, fragility, wrinkles, laxity, impaired wound healing, and a microenvironment conducive to cancer. However, the key factors responsible for these changes have not been fully elucidated, and relevant models for the study of skin aging progression are lacking. CCN1, a secreted extracellular matrix‒associated matricellular protein, is elevated in dermal fibroblasts in aged human skin. Toward constructing a mouse model to study the key factors involved in skin-aging progression, we demonstrate that transgenic mice, with selective expression of CCN1 in dermal fibroblasts (COL1A2-CCN1), display accelerated skin dermal aging. The aged phenotype in COL1A2-CCN1 mice resembles aged human dermis: the skin is wrinkled and the dermis is thin and composed of loose, disorganized, and fragmented collagen fibrils. These dermal alterations reflect reduced production of collagen due to impaired TGFβ signaling and increased expression of matrix metalloproteinases driving the induction of c-Jun/activator protein-1. Importantly, similar mechanisms drive human dermal aging. Taken together, the data demonstrate that elevated expression of CCN1 by dermal fibroblasts functions as a key mediator of dermal aging. The COL1A2-CCN1 mouse model provides a novel tool for understanding and studying the mechanisms of skin aging and age-related skin disorders.

The Pre-Treatment C-Reactive Protein Represents a Prognostic Factor in Patients with Oral and Oropharyngeal Cancer Treated with Radiotherapy

The purpose of the present study was to evaluate the prognostic significance of the pre- treatment C-reactive protein (CRP) level in a cohort of 503 patients with oral and oropharyngeal cancer treated at a tertiary academic center between 2000 and 2017. Cancer-specific survival (CSS), overall survival (OS) and loco-regional control (LC) were calculated using Kaplan-Meier analysis. To evaluate the prognostic value of the CRP level for the clinical endpoints, univariate and multivariate Cox regression models were applied. The median follow-up period was 61 months. Patients were divided into elevated CRP (≥5 mg/L) and normal CRP groups, according to pre-treatment plasma levels. An increased CRP level was significantly associated with shorter CSS (p < 0.001, log-rank test), as well as with shorter OS (p < 0.001, log-rank test) and loco-regional control (p = 0.001, log-rank test). In addition, multivariate analysis identified CRP as an independent predictor for CSS (hazard ratio (HR) 1.59, 95% confidence interval (CI) 1.08-2.35; p = 0.020) as well as for OS (HR 1.62, 95%CI 1.17-2.24; p = 0.004) and LC (HR 1.50, 95%CI 1.06-2.14; p = 0.023). In subgroup analysis, Kaplan Meier curves revealed that an elevated pre-treatment CRP level was a consistent prognostic factor for poor CSS (p = 0.003, log-rank test), OS (p = 0.001, log-rank test), and LC (p = 0.028, log-rank test) in patients treated with definitive (chemo-) radiotherapy, whereas a significant association in patients undergoing surgery and postoperative radiotherapy was not detected. The pre-treatment CRP level seems to represent a prognostic factor for CSS, OS, and LC in patients with oral and oropharyngeal cancer, particularly in those treated with definitive (chemo-) radiotherapy. Additional large-scale prospective studies are warranted to confirm and extend our findings.

Oncolytic adenovirus targeting TGF-β enhances anti-tumor responses of mesothelin-targeted chimeric antigen receptor T cell therapy against breast cancer

Chimeric antigen receptor (CAR)-modified T cell therapy evokes only modest antitumor responses in solid tumors. Meso-CAR-T cells are CAR-T cells targeted mesothelin, which are over-expressed in tumor tissues of breast cancer patients. To improve the therapeutic effects, we combined it with rAd.sT, a transforming growth factor β signaling-targeted oncolytic adenovirus, to therapy breast cancer. In subcutaneous MDA-MB-231 xenograft of NSG mice, both rAd.sT and meso-CAR-T inhibited tumor growth, however combination therapy produced stronger inhibitory effects. Interestingly, rAd.sT reduced tumor burden at initial stage following vector treatments, while meso-CAR-T cells decreased tumor burden at a later stage. Moreover, meso-CAR-T could target tumor microenvironments, and combination therapy could enhance cytokines production, such as interleukin (IL)-6 and IL-12 in tumor microenvironment. In conclusion, combination of rAd.sT with meso-CAR-T produced much more impressive antitumor responses to breast cancer and its metastasis, which could be developed as a promising therapeutic strategy.

Transforming Growth Factor-β Signaling in Immunity and Cancer

Transforming growth factor (TGF)-β is a crucial enforcer of immune homeostasis and tolerance, inhibiting the expansion and function of many components of the immune system. Perturbations in TGF-β signaling underlie inflammatory diseases and promote tumor emergence. TGF-β is also central to immune suppression within the tumor microenvironment, and recent studies have revealed roles in tumor immune evasion and poor responses to cancer immunotherapy. Here, we present an overview of the complex biology of the TGF-β family and its context-dependent nature. Then, focusing on cancer, we discuss the roles of TGF-β signaling in distinct immune cell types and how this knowledge is being leveraged to unleash the immune system against the tumor.

Transforming Growth Factor-β Signaling in Immunity and Cancer

Transforming growth factor (TGF)-β is a crucial enforcer of immune homeostasis and tolerance, inhibiting the expansion and function of many components of the immune system. Perturbations in TGF-β signaling underlie inflammatory diseases and promote tumor emergence. TGF-β is also central to immune suppression within the tumor microenvironment, and recent studies have revealed roles in tumor immune evasion and poor responses to cancer immunotherapy. Here, we present an overview of the complex biology of the TGF-β family and its context-dependent nature. Then, focusing on cancer, we discuss the roles of TGF-β signaling in distinct immune cell types and how this knowledge is being leveraged to unleash the immune system against the tumor.

Platelets and extracellular vesicles in cancer: diagnostic and therapeutic implications

Several pieces of evidence support the role of activated platelets in the development of the chronic inflammation-related diseases, such as atherothrombosis and cancer, mainly via the release of soluble factors and microparticles (MPs). Platelets and MPs contain a repertoire of proteins and genetic material (i.e., mRNAs and microRNAs) which may be influenced by the clinical condition of the individuals. In fact, platelets are capable of up-taking proteins and genetic material during their lifespan. Moreover, the content of platelet-derived MPs can be delivered to other cells, including stromal, immune, epithelial, and cancer cells, to change their phenotype and functions, thus contributing to cancer promotion and its metastasization. Platelets and MPs can play an indirect role in the metastatic process by helping malignant cells to escape from immunological surveillance. Furthermore, platelets and their derived MPs represent a potential source for blood biomarker development in oncology. This review provides an updated overview of the roles played by platelets and MPs in cancer and metastasis formation. The possible analysis of platelet and MP molecular signatures for the detection of cancer and monitoring of anticancer treatments is discussed. Finally, the potential use of MPs as vectors for drug delivery systems to cancer cells is put forward.

Tumour-vasculature development via endothelial-to-mesenchymal transition after radiotherapy controls CD44v6+ cancer cell and macrophage polarization

It remains controversial whether targeting tumour vasculature can improve radiotherapeutic efficacy. We report that radiation-induced endothelial-to-mesenchymal transition (EndMT) leads to tumour vasculature with abnormal SMA⁺NG2⁺ pericyte recruitment during tumour regrowth after radiotherapy. Trp53 (but not Tgfbr2) deletion in endothelial cells (ECs) inhibited radiation-induced EndMT, reducing tumour regrowth and metastases with a high CD44v6⁺ cancer-stem-cell (CSC) content after radiotherapy. Osteopontin, an EndMT-related angiocrine factor suppressed by EC-Trp53 deletion, stimulated proliferation in dormant CD44v6⁺ cells in severely hypoxic regions after radiation. Radiation-induced EndMT significantly regulated tumour-associated macrophage (TAM) polarization. CXCR4 upregulation in radioresistant tumour ECs was highly associated with SDF-1⁺ TAM recruitment and M2 polarization of TAMs, which was suppressed by Trp53 deletion. These EndMT-related phenomena were also observed in irradiated human lung cancer tissues. Our findings suggest that targeting tumour EndMT might enhance radiotherapy efficacy by inhibiting the re-activation of dormant hypoxic CSCs and promoting anti-tumour immune responses.

Radiotherapy is the main treatment for most cancer, but it is unclear if targeting tumour vasculature can enhance tumour radiosensitivity. Here, the authors show that tumour endothelial-mesenchymal transition after radiotherapy leads to proliferation of radioresistant CSCs and tumour associated macrophages polarization.

BMP7 Signaling in TGFBR2-Deficient Stromal Cells Provokes Epithelial Carcinogenesis

Deregulated transforming growth factor-β (TGFβ) signaling is a common feature of many epithelial cancers. Deletion of TGFβ receptor type 2 (TGFBR2) in fibroblast specific protein-1 (FSP1)-positive stromal cells induces squamous cell carcinoma in the murine forestomach, implicating fibroblast-derived hepatocyte growth factor (HGF) as the major driver of the epithelium carcinogenesis. Prior to cancer development, hyperproliferative FSP1⁺ fibroblasts lacking TGFBR2 accumulate in the forestomach, disrupting the regulatory signaling cross-talk with the forestomach epithelium. Here, concurrent loss in TGFBR2 and SMAD4 completely abrogates the development of forestomach cancer. Bone morphogenic protein-7 (BMP7) was highly upregulated in forestomach cancer tissue, activating Smad1/5/8 signaling, cell proliferation, and HGF production in TGFBR2-deficient FSP1⁺ fibroblasts. This stimulation by BMP7 was lost in the combined TGFBR2 and SMAD4 double knockout fibroblasts, which included a profound decrease in HGF expression. Thus, Smad4-mediated signaling is required to initiate epithelial carcinogenesis subsequent to TGFBR2 deletion in FSP1⁺ fibroblasts.Implications: These findings reveal a complex cross-talk between epithelial cells and the stroma, wherein Smad4 is required to elicit squamous cell carcinomas in the forestomach of mice with TGFBR2-deficient stromal cells. Mol Cancer Res; 16(10); 1568-78. ©2018 AACR.

Oesophageal Stem Cells and Cancer

Oesophageal cancer remains one of the least explored malignancies. However, in recent years its increasing incidence and poor prognosis have stimulated interest from the cancer community to understand the pathways to the initiation and progression of the disease.

Critical understanding of the molecular processes controlling changes in stem cell fate and the cross-talk with their adjacent stromal neighbours will provide essential knowledge on the mechanisms that go awry in oesophageal carcinogenesis. Advances in lineage tracing techniques have represented a powerful tool to start understanding changes in oesophageal cell behaviour in response to mutations and mutagens that favour tumour development.

Environmental cues constitute an important factor in the aetiology of oesophageal cancer. The oesophageal epithelium is a tissue exposed to harsh conditions that not only damage the DNA of epithelial cells but also result in an active stromal reaction, promoting tumour progression. Ultimately, cancer represents a complex interplay between malignant cells and their microenvironment. Indeed, increasing evidence suggests that the accumulation of somatic mutations is not the sole cause of cancer. Instead, non-cell autonomous components, coming from the stroma, can significantly contribute from the earliest stages of tumour formation.

The realisation that stromal cells play an important role in cancer has transformed this cellular compartment into an attractive and emerging field of research. It is becoming increasingly clear that the tumour microenvironment provides unique opportunities to identify early diagnostic and prognostic markers, as well as potential therapeutic strategies that may synergise with those targeting tumour cells.

This chapter compiles recent observations on oesophageal epithelial stem cell biology, and how environmental and micro-environmental changes may lead to oesophageal disease and cancer.

Genetics of metastasis: melanoma and other cancers

Melanoma is a malignant neoplasm of melanocytes that accounts for the majority of skin cancer deaths despite comprising less than 5% of all cutaneous malignancies. Its incidence has increased faster than that of any other cancer over the past half-century and the annual costs of treatment in the United States alone have risen rapidly. Although the majority of primary melanomas are cured with local excision, metastatic melanoma historically carries a grim prognosis, with a median survival of 9 months and a long-term survival rate of 10%. Given the urgent need to develop treatment strategies for metastatic melanoma and the explosion of genetic technologies over the past 20 years, there has been extensive research into the genetic alterations that cause melanocytes to become malignant. More recently, efforts have focused on the genetic changes that drive melanoma metastasis. This review aims to summarize the current knowledge of the genetics of primary cutaneous and ocular melanoma, the genetic changes associated with metastasis in melanoma and other cancer types, and non-genetic factors that may contribute to metastasis.

Major Challenges and Potential Microenvironment-Targeted Therapies in Glioblastoma

Glioblastoma (GBM) is considered one of the most malignant, genetically heterogeneous, and therapy-resistant solid tumor. Therapeutic options are limited in GBM and involve surgical resection followed by chemotherapy and/or radiotherapy. Adjuvant therapies, including antiangiogenic treatments (AATs) targeting the VEGF–VEGFR pathway, have witnessed enhanced infiltration of bone marrow-derived myeloid cells, causing therapy resistance and tumor relapse in clinics and in preclinical models of GBM. This review article is focused on gathering previous clinical and preclinical reports featuring major challenges and lessons in GBM. Potential combination therapies targeting the tumor microenvironment (TME) to overcome the myeloid cell-mediated resistance problem in GBM are discussed. Future directions are focused on the use of TME-directed therapies in combination with standard therapy in clinical trials, and the exploration of novel therapies and GBM models for preclinical studies. We believe this review will guide the future of GBM research and therapy.

Mechanisms that drive inflammatory tumor microenvironment, tumor heterogeneity, and metastatic progression

Treatment of cancer metastasis has been largely ineffective. It is paramount to understand the mechanisms underlying the metastatic process, of which the tumor microenvironment is an indispensable participant. What are the critical cellular and molecular players at the primary tumor site where metastatic cascade initiates? How is tumor-associated inflammation regulated? How do altered vasculatures contribute to metastasis? What is the dynamic nature or heterogeneity of primary tumors and what are the challenges to catch a moving target? This review summarizes recent progress, mechanistic understanding, and options for metastasis-targeted therapy.

Clinical characteristics of angioimmunoblastic T-cell lymphoma in China and C-reactive protein as an independent prognostic factor

Angioimmunoblastic T-cell lymphoma (AITL) is a major subtype of peripheral T-cell lymphoma (PTCL). Due to its low incidence, the characteristics of AITL are still not well understood. The prognostic evaluation of this disease has not been established.We retrospectively analyzed 52 patients with newly diagnosed AITL in China between January 2008 and September 2016.Among these patients, the median age at diagnosis was 62 (40-83) and 58% (30/52) of the patients were older than 60 years. Thirty-five patients were male, accounting for 67.3% of the whole. Among these, 90% (47/52) of the diagnoses were estimated at advanced stage. A total of 25 (48%) patients were scored >1 by the ECOG performance status. Systemic B symptoms were described in 34 (65%) patients. When evaluated by International Prognostic Index (IPI), 81% were scored >2, and 77% got >1 score according to the prognostic index for PTCL (PIT) upon diagnosis. The 3-year progression-free survival (PFS) was 44% and the 3-year overall survival (OS) rate was 52%. IPI and PIT scores could not be effectively applied to stratify those AITL patients into subgroups. Our multivariate analysis results found that the elevated serum C-reactive protein (CRP) level was an independent adverse factor to the OS of the AITL patients.Patients with AITL had a poor outcome. The serum level of CRP may be applied as an independent prognostic factor for AITL.

Transcriptome analysis of human colorectal cancer biopsies reveals extensive expression correlations among genes related to cell proliferation, lipid metabolism, immune response and collagen catabolism

Precise characterization of biological processes critical to proliferation and metastasis of colorectal cancer should facilitate the development of diagnostic and prognostic biomarkers as well as novel treatments. Using mRNA-Seq, we examined the protein coding messenger RNA (mRNA) expression profiles across different histologically defined stages of primary colon cancers and compared them to their patient matched normal tissue controls. In comparing 79 colorectal cancers to their matched normal mucosa, tumors were distinguished from normal non-malignant tissues not only in the upregulation of biological processes pertaining to cell proliferation, inflammation, and tissue remodeling, but even more strikingly, in downregulated biological processes including fatty acid beta oxidization for ATP production and epithelial cell differentiation and function. A network analysis of deregulated genes revealed newly described cancer networks and putative hub genes.

Taken together, our findings suggest that, within an inflammatory microenvironment, invasive, dedifferentiated and rapidly dividing tumor cells divert the oxidation of fatty acids and lipids from energy production into lipid components of cell membranes and organelles to support tumor proliferation. A gene co-expression network analysis provides a clear and broad picture of biological pathways in tumors that may significantly enhance or supplant current histopathologic studies.

TGF-β, Bone Morphogenetic Protein, and Activin Signaling and the Tumor Microenvironment

The cellular and noncellular components surrounding the tumor cells influence many aspects of tumor progression. Transforming growth factor β (TGF-β), bone morphogenetic proteins (BMPs), and activins have been shown to regulate the phenotype and functions of the microenvironment and are attractive targets to attenuate protumorigenic microenvironmental changes. Given the pleiotropic nature of the cytokines involved, a full understanding of their effects on numerous cell types in many contexts is necessary for proper clinical intervention. In this review, we will explore the various effects of TGF-β, BMP, and activin signaling on stromal phenotypes known to associate with cancer progression. We will summarize these findings in the context of their tumor suppressive or promoting effects, as well as the molecular changes that these cytokines induce to influence stromal phenotypes.

Concomitant underexpression of TGFBR2 and overexpression of hTERT are associated with poor prognosis in cervical cancer

The human telomerase reverse transcriptase (hTERT) is highly expressed in a variety of tumors. The transforming growth factor beta receptor type II (TGFBR2) is a downstream protein of transforming growth factor beta (TGF-β) which suppresses telomerase activity. However, the relevance of survival to the expression of TGFBR2, hTERT or TGFBR2/hTERT has not been previously investigated in cervical cancer tissues. Our study showed that patients with low level of TGFBR2 were associated with poor prognosis (HR = 1.704, P = 0.021), but no significant relevance between hTERT expression and survival (HR = 1.390, P = 0.181). However, a combination of low level of TGFBR2 and high level of hTERT was associated with a worse survival (HR = 1.892, P = 0.020), which had higher impact of hazard ratio (HR) on the overall survival (OS) than the low TGFBR2 expression alone. Knockdown of TGFBR2 expression by shRNA in Hela cells increased cell proliferation, cell invasion, G1/S transition and telomere homeostasis but decreased cell apoptosis. Overexpressing TGFBR2 and inhibiting hTERT suppressed Hela cell growth. These results would lead us to further explore whether a phenotype of TGFBR2^low/hTERT^high could be considered as a predictor of poor prognosis, and whether simultaneous use of TGFBR2 agonist and hTERT inhibitor could be developed as a therapeutic strategy.

Mammary Gland Involution Provides a Unique Model to Study the TGF-β Cancer Paradox

Transforming Growth Factor-β (TGF-β) signaling in cancer has been termed the “TGF-β paradox”, acting as both a tumor suppresser and promoter. The complexity of TGF-β signaling within the tumor is context dependent, and greatly impacted by cellular crosstalk between TGF-β responsive cells in the microenvironment including adjacent epithelial, endothelial, mesenchymal, and hematopoietic cells. Here we utilize normal, weaning-induced mammary gland involution as a tissue microenvironment model to study the complexity of TGF-β function. This article reviews facets of mammary gland involution that are TGF-β regulated, namely mammary epithelial cell death, immune activation, and extracellular matrix remodeling. We outline how distinct cellular responses and crosstalk between cell types during physiologically normal mammary gland involution contribute to simultaneous tumor suppressive and promotional microenvironments. We also highlight alternatives to direct TGF-β blocking anti-cancer therapies with an emphasis on eliciting concerted microenvironmental-mediated tumor suppression.

Runx3 in Immunity, Inflammation and Cancer

In this chapter we summarize the pros and cons of the notion that Runx3 is a major tumor suppressor gene (TSG). Inactivation of TSGs in normal cells provides a viability/growth advantage that contributes cell-autonomously to cancer. More than a decade ago it was suggested that RUNX3 is involved in gastric cancer development, a postulate extended later to other epithelial cancers portraying RUNX3 as a major TSG. However, evidence that Runx3 is not expressed in normal gastric and other epithelia has challenged the RUNX3-TSG paradigm. In contrast, RUNX3 is overexpressed in a significant fraction of tumor cells in various human epithelial cancers and its overexpression in pancreatic cancer cells promotes their migration, anchorage-independent growth and metastatic potential. Moreover, recent high-throughput quantitative genome-wide studies on thousands of human samples of various tumors and new investigations of the role of Runx3 in mouse cancer models have unequivocally demonstrated that RUNX3 is not a bona fide cell-autonomous TSG. Importantly, accumulating data demonstrated that RUNX3 functions in control of immunity and inflammation, thereby indirectly influencing epithelial tumor development.

The hallmarks of CAFs in cancer invasion

The ability of cancer cells to move out of the primary tumor and disseminate through the circulation to form metastases is one of the main contributors to poor patient outcome. The tumor microenvironment provides a niche that supports cancer cell invasion and proliferation. Carcinoma-associated fibroblasts (CAFs) are a highly enriched cell population in the tumor microenvironment that plays an important role in cancer invasion. However, it remains unclear whether CAFs directly stimulate cancer cell invasion or they remodel the extracellular matrix to make it more permissive for invasion. Here we discuss paracrine communication between cancer cells and CAFs that promotes tumor invasion but also stimulates CAFs to remodel the matrix increasing cancer dissemination.

Prognostic and Predictive Value of Serum C-Reactive Protein Levels in Patients with Metastatic Or Locally Recurrent Gastric Cancer

Background and Aims

Increasing evidence suggests that elevated serum levels of C-reactive protein (CRP) are associated with poor survival in many malignant tumors. However, the prognostic value of CRP in advanced gastric cancer (AGC) remains uncertain. This study was undertaken to evaluate the significance of serum CRP as a biomarker of long-term survival in patients with AGC.

Methods

The serum CRP levels of AGC patients were analyzed for clinicopathological significance. Data were collected retrospectively for 244 patients treated between October 1, 2006 and September 30, 2013. The prognostic effect of serum CRP levels was evaluated.

Results

The baseline CRP level before chemotherapy was significantly associated with overall survival. The median survival was 351 days for patients with CRP ≥10 mg/L and 370 days for patients with CRP c10 mg/L (p = 0.033). Cox analysis revealed CRP to be an independent prognostic factor for overall survival. In the 93 patients whose baseline CRP was ≥10 mg/L, a cutoff point of 22% for the CRP declining rate provided optimum sensitivity and specificity for 1-year survival based on ROC curves. A CRP declining rate >22% was found to predict longer overall survival (410 days versus 299 days; p = 0.001).

Conclusions

Elevated serum CRP baseline levels before chemotherapy were associated with reduced overall survival in patients with AGC. The CRP declining rate was also associated with overall survival. The CRP baseline concentration before chemotherapy and CRP declining rate after chemotherapy may be used as novel, widely available and real-time independent prognostic and predictive markers of AGC.

C-Reactive Protein is a Prognostic Marker for Patients with Castration-Resistant Prostate Cancer

INTRODUCTION

As an acute-phase protein synthesized in response to systemic inflammation, the C-reactive protein (CRP) has been shown to be an independent prognostic factor for patients with castration-resistant prostate cancer (CRPC). The aim of this study was to investigate the association between CRP and progression-free survival (PFS), overall survival (OS) and radiological response in CRPC patients treated with docetaxel.

METHODS

115 histologically confirmed CRPC patients who were treated with docetaxel chemotherapy from 2008 to 2013 were selected. Univariable and multivariable Cox regression models were used to predict the association of CRP as a dichotomous variable with PFS and OS after chemotherapy initiation.

RESULTS

None of the clinicopathological features were associated with the CRP. In Kaplan-Meier analysis, the median PFS (9.8 vs. 7.5 months, p < 0.001) and OS (26.5 vs. 13.5 months, p = 0.002) were higher in patients who did not have an elevated CRP than in those with an elevated CRP. In univariable analysis, the pretreatment CRP was significantly associated with PFS (p < 0.001) and OS (p = 0.003).In multivariable analysis, patients with a CRP > 8 mg/l were at significantly higher risk of tumor progress (hazard ratio (HR) 2.184; 95% confidence interval (CI) 1.401-3.403; p = 0.001) and death (HR 2.003; 95% CI 1.285-3.121; p = 0.002) than patients with a CRP ≤ 8 mg/l.

CONCLUSIONS

CRP may be an important biomarker of PFS and OS in CRPC patients treated with docetaxel. The findings require validation in further prospective, large cohort-size studies.

The role of cancer-associated fibroblasts in esophageal cancer

Fibroblasts are known as critical stromal cells in wound healing by synthesizing extracellular matrix and collagen. A subpopulation of them is called cancer-associated fibroblasts (CAFs), because their production of proteins participated in various biological activities including tumor cell proliferation, invasion and metastasis. Currently some studies shed light on their role in esophageal cancer which was an aggressive cancer with a dismal survival and high rate of metastasis. Thus, to find cures for it relies on elucidating the epithelial-fibroblasts crosstalk. Herein, we reviewed the present knowledge of the CAFs’ role in esophageal premalignant condition, cancer initiation, progression, metastasis and prognosis prediction and further provided some insights into its clinical application.

Disruptive environmental chemicals and cellular mechanisms that confer resistance to cell death

Cell death is a process of dying within biological cells that are ceasing to function. This process is essential in regulating organism development, tissue homeostasis, and to eliminate cells in the body that are irreparably damaged. In general, dysfunction in normal cellular death is tightly linked to cancer progression. Specifically, the up-regulation of pro-survival factors, including oncogenic factors and antiapoptotic signaling pathways, and the down-regulation of pro-apoptotic factors, including tumor suppressive factors, confers resistance to cell death in tumor cells, which supports the emergence of a fully immortalized cellular phenotype. This review considers the potential relevance of ubiquitous environmental chemical exposures that have been shown to disrupt key pathways and mechanisms associated with this sort of dysfunction. Specifically, bisphenol A, chlorothalonil, dibutyl phthalate, dichlorvos, lindane, linuron, methoxychlor and oxyfluorfen are discussed as prototypical chemical disruptors; as their effects relate to resistance to cell death, as constituents within environmental mixtures and as potential contributors to environmental carcinogenesis.

Genetic instability in the tumor microenvironment: a new look at an old neighbor

The recent exponential increase in our knowledge of cellular and molecular mechanisms involved in carcinogenesis has largely failed to translate into new therapies and clinical practices. This lack of success may result in part from the fact that most studies focus on tumor cells as potential therapeutic targets and neglect the complex microenvironment that undergoes profound changes during tumor development. Furthermore, an unfortunate association of factors such as tumor genetic complexity, overestimation of biomarker and drug potentials, as well as a poor understanding of tumor microenvironment in diagnosis and prognosis leads to the current levels of treatment failure regarding a vast majority of cancer types. A growing body of evidence points to the importance of the functional diversity of immune and structural cells during tumor development. In this sense, the lack of technologies that would allow for molecular screening of individual stromal cell types poses a major challenge for the development of therapies targeting the tumor microenvironment. Progress in microenvironment genetic studies represents a formidable opportunity for the development of new selective drugs because stromal cells have lower mutation rates than malignant cells, and should prove to be good targets for therapy.

Runx3 at the interface of immunity, inflammation and cancer

Inactivation of tumor suppressor genes (TSG) in normal cells provides a viability/growth advantage that contributes cell-autonomously to cancer. More than a decade ago claims arose that the RUNX3 member of the RUNX transcription factor family is a major TSG inactivated in gastric cancer, a postulate extended later to other cancers. However, evidence that Runx3 is not expressed in normal gastric and other epithelia has challenged the RUNX3-TSG paradigm. Here we critically re-appraise this paradigm in light of recent high-throughput, quantitative genome-wide studies on thousands of human samples of various tumors and new investigations of the role of Runx3 in mouse cancer models. Collectively, these studies unequivocally demonstrate that RUNX3 is not a bona fide cell-autonomous TSG. Accordingly, RUNX3 is not recognized as a TSG and is not included among the 2000 cancer genes listed in the "Cancer Gene Census" or "Network for Cancer Genes" repositories. In contrast, RUNX3 does play important functions in immunity and inflammation and may thereby indirectly influence epithelial tumor development.

Role of TGFβ in regulation of the tumor microenvironment and drug delivery (review)

Deregulation of cell signaling homeostasis is a predominant feature of cancer initiation and progression. Transforming growth factor β (TGFβ) is a pleiotropic cytokine, which regulates numerous biological processes of various tissues in an autocrine and paracrine manner. Aberrant activity of TGFβ signaling is well known to play dual roles in cancer, depending on tumor stage and cellular context. The crucial roles of TGFβ in modulating the tumor microenvironment, its contribution to the accumulation of mechanical forces within the solid constituents of a tumor and its effects on the effective delivery of drugs are also becoming increasingly clear. In this review, we discuss the latest advances in the efforts to unravel the effects of TGFβ signaling in various components of the tumor microenvironment and how these influence the generation of forces and the efficacy of drugs. We also report the implications of tumor mechanics in cancer therapy and the potential usage of anti-TGFβ agents to enhance drug delivery and augment existing therapeutic approaches. These findings provide new insights towards the significance of targeting TGFβ pathway to enhance personalized tumor treatment.

Roles of tumor suppressors in regulating tumor-associated inflammation

Loss or silencing of tumor suppressors (TSs) promotes neoplastic transformation and malignant progression. To date, most work on TS has focused on their cell autonomous effects. Recent evidence, however, demonstrates an important noncell autonomous role for TS in the control of tumor-associated inflammation. We review evidence from clinical data sets and mouse model studies demonstrating enhanced inflammation and altered tumor microenvironment (TME) upon TS inactivation. We discuss clinical correlations between tumor-associated inflammation and inactivation of TS, and their therapeutic implications. This review sets forth the concept that TS can also suppress tumor-associated inflammation, a concept that provides new insights into tumor-host interactions. We also propose that in some cases the loss of TS function in cancer can be overcome through inhibition of the resulting inflammatory response, regardless whether it is a direct or an indirect consequence of TS loss.

Roles of tumor suppressors in regulating tumor-associated inflammation

Loss or silencing of tumor suppressors (TSs) promotes neoplastic transformation and malignant progression. To date, most work on TS has focused on their cell autonomous effects. Recent evidence, however, demonstrates an important noncell autonomous role for TS in the control of tumor-associated inflammation. We review evidence from clinical data sets and mouse model studies demonstrating enhanced inflammation and altered tumor microenvironment (TME) upon TS inactivation. We discuss clinical correlations between tumor-associated inflammation and inactivation of TS, and their therapeutic implications. This review sets forth the concept that TS can also suppress tumor-associated inflammation, a concept that provides new insights into tumor-host interactions. We also propose that in some cases the loss of TS function in cancer can be overcome through inhibition of the resulting inflammatory response, regardless whether it is a direct or an indirect consequence of TS loss.

The contribution of neuronal-glial-endothelial-epithelial interactions to colon carcinogenesis

Several different cell types constitute the intestinal wall and interact in different manners to maintain tissue homeostasis. Elegant reports have explored these physiological cellular interactions revealing that glial cells and neurons not only modulate peristalsis and mechanical stimulus in the intestines but also control epithelial proliferation and sub-epithelial angiogenesis. Although colon carcinoma arises from epithelial cells, different sub-epithelial cell phenotypes are known to support the manifestation and development of tumors from their early steps on. Therefore, new perspectives in cancer research have been proposed, in which neurons and glial cells not only lead to higher cancer cell proliferation at the tumor invasion front but also further enhance angiogenesis and neurogenesis in tumors. Transformation of physiological neural activity into a pro-cancer event is thus discussed for colon carcinogenesis herein.

BMPR2 loss in fibroblasts promotes mammary carcinoma metastasis via increased inflammation

Bone Morphogenetic Protein (BMP) receptors mediate a diverse range of signals to regulate both development and disease. BMP activity has been linked to both tumor promoting and suppressive functions in both tumor cells and their surrounding microenvironment. We sought to investigate the requirement for BMPR2 in stromal fibroblasts during mammary tumor formation and metastasis. We utilized FSP1 (Fibroblast Specific Protein-1) promoter driven Cre to genetically delete BMPR2 in mice expressing the MMTV.PyVmT mammary carcinoma oncogene. We found that abrogation of stromal BMPR2 expression via FSP1 driven Cre resulted in increased tumor metastasis. Additionally, similar to epithelial BMPR2 abrogation, stromal loss of BMPR2 results in increased inflammatory cell infiltration. We proceeded to isolate and establish fibroblast cell lines without BMPR2 and found a cell autonomous increase in inflammatory cytokine secretion. Fibroblasts were co-implanted with syngeneic tumor cells and resulted in accelerated tumor growth and increased metastasis when fibroblasts lacked BMPR2. We observed that the loss of BMPR2 results in increased chemokine expression, which facilitates inflammation by a sustained increase in myeloid cells. The chemokines increased in BMPR2 deleted cells correlated with poor outcome in human breast cancer patients. We conclude that BMPR2 has tumor suppressive functions in the stroma by regulating inflammation.

Vicious cycle of TGF-β signaling in tumor progression and metastasis

TGF-β is an important biological mediator. It regulates a wide range of functions including embryonic development, wound healing, organ development, immuno-modulation, and cancer progression. Interestingly, TGF-β is known to inhibit cell growth in benign cells but promote progression in cancer cells, a phenomenon known as TGF-β paradox. TGF-β stimulation in cancer cells leads to a differential Erk activation, which srves as the basis of TGF-β paradox between benign and cancer cells. The critical events of TGF-β mediated Erk activation are suppressed TBRs and elevated TGF-β in tumor cells but not in benign cells. These events form the basis of the "vicious cycle of TGF-β signaling". The term "vicious cycle", implies that, with each advancing cycle of TGF-β signaling, the tumor will accumulate more TGF-β and will be more "aggressive" than that of the previous cycle. Understanding this vicious cycle of TGF-β signaling in tumor progression and metastasis will help us to predict indolent from aggressive cancers and will help us to develop novel anti-cancer strategies.

Myeloid Derived Suppressor Cells: Fuel the Fire

Low oxygen tension, hypoxia, is a characteristic of many tumors and associated with the poor prognosis. Hypoxia invites bone marrow derived cells (BMDCs) from bone marrow to the site of tumor. These recruited CXCR4+ BMDCs provide favorable environment for the tumor growth by acquiring pro-angiogenic phenotype such as CD45+VEGFR2+ Endothelial Progenitor Cells (EPC), or CD45+Tie2+ myeloid cells. CD11b+CD13+ myeloid population of the BMDCs modulate tumor progression. These myeloid populations retain immunosuppressive characteristics, for example, myeloid derived suppressor cells (MDSCs), and regulates immune- suppression by inhibiting cytotoxic T cell function. In addition, MDSCs were observed at the premetastatic niche of the distant organs in other tumors. Protumorigenic and prometastatic role of the myeloid cells provides a basis for therapeutic targeting of immunosuppression and thus inhibiting tumor development and metastasis.

Inflammatory cues acting on the adult intestinal stem cells and the early onset of cancer (review)

The observation that cancer often arises at sites of chronic inflammation has prompted the idea that carcinogenesis and inflammation are deeply interwoven. In fact, the current literature highlights a role for chronic inflammation in virtually all the steps of carcinogenesis, including tumor initiation, promotion and progression. The aim of the present article is to review the current literature on the involvement of chronic inflammation in the initiation step and in the very early phases of tumorigenesis, in a type of cancer where adult stem cells are assumed to be the cells of origin of neoplasia. Since the gastrointestinal tract is regarded as the best-established model system to address the liaison between chronic inflammation and neoplasia, the focus of this article will be on intestinal cancer. In fact, the anatomy of the intestinal epithelial lining is uniquely suited to study adult stem cells in their niche, and the bowel crypt is an ideal developmental biology system, as proliferation, differentiation and cell migration are all distributed linearly along the long axis of the crypt. Moreover, crypt stem cells are regarded today as the most likely targets of neoplastic transformation in bowel cancer. More specifically, the present review addresses the molecular mechanisms whereby a state of chronic inflammation could trigger the neoplastic process in the intestine, focusing on the generation of inflammatory cues evoking enhanced proliferation in cells not initiated but at risk of neoplastic transformation because of their stemness. Novel experimental approaches, based on triggering an inflammatory stimulus in the neighbourhood of adult intestinal stem cells, are warranted to address some as yet unanswered questions. A possible approach, the targeted transgenesis of Paneth cells, may be aimed at 'hijacking' the crypt stem cell niche from a status characterized by the maintenance of homeostasis to local chronic inflammation, with the prospect of initiating neoplastic transformation in that site.