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BACKGROUND The current curative approaches for ischemia/reperfusion injury on liver transplantation are still under debate for their safety and efficacy in patients with end-stage liver disease. We present the SIMVA statin donor treatment before Liver Transplants study. METHODS SIMVA statin donor treatment before Liver Transplants is a monocentric, double-blind, randomized, prospective tial aiming to compare the safety and efficacy of preoperative brain-dead donors' treatment with the intragastric administration of 80 mg of simvastatin on liver transplant recipient outcomes in a real-life setting. Primary aim was incidence of patient and graft survival at 90 and 180 d post-transplant; secondary end-points were severe complications. RESULTS The trial enrolled 58 adult patients (18-65 y old). The minimum follow-up was 6 mo. No patient or graft was lost at 90 or 180 d in the experimental group (n = 28), whereas patient/graft survival were 93.1% (P = 0.016) and 89.66% (P = 0.080) at 90 d and 86.21% (P = 0.041) and 86.2% (P = 0.041) at 180 d in the control group (n = 29). The percentage of patients with severe complications (Clavien-Dindo ≥IIIb) was higher in the control group, 55.2% versus 25.0% in the experimental group (P = 0.0307). The only significant difference in liver tests was a significantly higher gamma-glutamyl transferase and alkaline phosphatase at 15 d (P = 0.017), (P = 0.015) in the simvastatin group. CONCLUSIONS Donor simvastatin treatment is safe, and may significantly improve early graft and patient survival after liver transplantation, although further research is mandatory.

Background: Hepatic interstitial T-lymphocytes (T-Li), Natural Killer (NK) and NK-T cells play an important role in both innate and adaptive immunity and contribute to the regulation of ischemia/reperfusion injury (IRI) after transplantation of abdominal organ. Methods: The cellular concentrations and phenotypes of NK, T-Li, NK-T were analyzed retrospectively in a consecutive series of hepatic perfusates after surgical removal of whole livers on the bench previously collected from adult multi-organ donors after brain death. (DBD), and compared with the demographic and pathological characteristics of the patients transplanted at our Institute with kidneys taken from the same donors. The liver interstitial cells were purified from the perfusate by density gradient centrifugation and the phenotype was determined by flow cytometric investigation using the following immunological markers: CD3, CD4, CD8 and CD56 in order to determine the relative percentage of T-Li, NK-T and NK cells. Results: The perfusates of 42 DBDs, and the related clinical outcome of kidney transplant recipients from 2010 to 2020, were analyzed. T-Li were significantly associated with the time in days of delayed functional recovery of transplanted kidneys (DGF) (p = 0.02), to onset of secondary infection from Cytomegalovirus (p = 0.03). On COX analysis, percent cell concentration of T-Li and time to DGF were significantly associated with an increased relative risk (HR) of organ survival (HR = 1.038, p = 0.04; and HR = 1.029, p = 0.01, respectively). The specificity of the NK and NK-T cell proportions were not associated with any relevant clinical outcomes in kidney transplant patients. Conclusions: The present study points to a new potential role of T-Li cells detected in the context of liver perfusate DBD, and could detect potential impacts in organ allocation, surgical harvesting techniques and in the analysis of IRI pathophysiological events after kidney transplants from multi-organ DBDs.

Chronic hepatitis C virus (HCV) infection is the principal etiology of cirrhosis and, ultimately, hepatocellular carcinoma (HCC). At present, approximately 71 million people are chronically infected with HCV, and 10%-20% of these are expected to develop severe liver complications throughout their lifetime. Scientific evidence has clearly shown the causal association between miRNAs, HCV infection and HCC. Although it is not completely clear whether miRNA dysregulation in HCC is the cause or the consequence of its development, variations in miRNA patterns have been described in different liver diseases, including HCC. Many studies have analyzed the importance of circulating miRNAs and their effect on cell proliferation and apoptosis. In this Review, we aim to summarize current knowledge on the association between miRNA, HCV and HCC from a diagnostic point of view, and also the potential implications for therapeutic approaches.

Over recent years, managing hypertension in older people has gained increasing attention, with reference to very old, frailer individuals. In these patients, hypertension treatment may be challenging due to a higher risk of hypotension-related adverse events which commonly overlaps with a higher cardiovascular risk. Additionally, frailer older adults rarely satisfy inclusion criteria of randomized clinical trials, which determines a substantial lack of scientific data. Although limited, available evidence suggests that the association between blood pressure and adverse outcomes significantly varies at advanced age according to frailty status. In particular, the negative prognostic impact of hypertension seems to attenuate or even revert in individuals with older biological age, e.g., patients with disability, cognitive impairment, and poor physical performance. Consequently, "one size does not fit all" and personalized treatment strategies are needed, customized to individuals' frailty and functional status. Similar to other cardiovascular diseases, hypertension management in older people should be characterized by a geriatric approach based on biological rather than chronological age and a geriatric comprehensive evaluation including frailty assessment is required to provide the most appropriate treatment, tailored to patients' prognosis and health care goals. The aim of this review was to illustrate the importance of a patient-centered geriatric approach to hypertension management in older people with the final purpose to promote a wider implementation of frailty assessment in routine practice.

Introduction Atrial fibrillation (AF) is the most common cardiac sustained arrhythmia, whose incidence and prevalence increase with age, representing a significant burden for health services in western countries. Older people contribute to the vast majority of patients affected from AF. Evidence acquisition Although oral anticoagulant therapy represents the cornerstone for the prevention of ischemic stroke and its disabling consequences, several other interventions - including left atrial appendage occlusion (LAAO), catheter ablation (CA) of AF, and rhythm control strategy (RCS) - have proved to be potentially effective in reducing the incidence of AF-associated clinical complications. Scientific literature focused on the three items will be discussed. Evidence synthesis Practical treatment of older AF patients is presented, including approach and management of patients with geriatric syndromes, selection of the most appropriate individualized drug treatment, clinical indications and potential clinical benefit of LAAO and CA in selected older AF patients. Conclusions Older people carry the greatest burden of AF in real world practice. Within a shared decision making process, the patient centered approach need to be put in the context of a comprehensive assessment, in order to gain maximal net clinical benefit and avoid futility or harm.

Principles and processes of comprehensive geriatric assessment (CGA) are increasingly being applied to subspecialties and subspecialty conditions, including cardiovascular patients (i.e., infective endocarditis; considerations of surgery or transcatheter aortic valve replacement, TAVR, for patients with aortic stenosis; vascular surgery) and postoperative mortality risk. In cardiovascular field CGA has mainly the aim to define ideal management according to the different typology of older adult patients (e.g., robust versus intermediate versus physical and cognitively disabled versus end-stage or dying), allowing physicians to select different therapeutic goals according to life expectancy; Aspect to be valued are by CGA are global health status and patient's decision-making capacity: CGA allows the individualized treatment definition and optimize the preprocedure condition.

Cancer immunotherapy has led to impressive advances in cancer treatment. Unfortunately, in a high percentage of patients is difficult to consistently restore immune responses to eradicate established tumors. It is well accepted that adaptive immune cells, such as B lymphocytes, CD4+helper T lymphocytes, and CD8+cytotoxic T-lymphocytes (CTLs), are the most effective cells able to eliminate tumors. However, it has been recently reported that innate immune cells, including natural killer cells (NK), dendritic cells (DC), macrophages, myeloid-derived suppressor cells (MDSCs), and innate lymphoid cells (ILCs), represent important contributors to modulating the tumor microenvironment and shaping the adaptive tumor response. In fact, their role as a bridge to adaptive immunity, make them an attractive therapeutic target for cancer treatment. Here, we provide a comprehensive overview of the pleiotropic role of tissue-resident innate immune cells in different tumor contexts. In addition, we discuss how current and future therapeutic approaches targeting innate immune cells sustain the adaptive immune system in order to improve the efficacy of current tumor immunotherapies.

Notch-1 pathway plays an important role in lung carcinoma, stem cell regulation, cellular communication, growth and differentiation. Cigarette smoke is involved in the regulation of Notch signaling. However, current data regarding the impact of cigarette smoke on the Notch pathway in lung cancer progression are limited. The present study aimed to explore whether cigarette smoke exposure altered Notch-1 pathway in ex-vivo (surgical samples of lung parenchyma from non-smoker and smoker patients with lung adenocarcinoma) and in vitro (adenocarcinoma A549 cell line) approaches. The expression of Notch-1, Jagged-1 and CD133 in surgical samples was evaluated by immunohistochemistry. A549 were exposed to cigarette smoke extracts (2.5% and 5% CSE for 6, 24 and 48 h) and the expression of Notch-1, Jagged-1 and Hes-1 was evaluated by Real-Time PCR and Western Blot (nuclear fractions). Expression and localization of Notch-1, Hes-1, CD133 and ABCG2 were assessed by immunofluorescence. The expression of survivin and Ki-67 was assessed by flow cytometry following CSE exposure and inhibition of Notch-1 signaling. Smokers lung parenchyma exhibited higher expression of Notch-1. CSE exposure increased Notch-1 and Hes-1 gene and nuclear protein expression in A549. Immunofluorescence confirmed higher expression of nuclear Hes-1 in CSE-stimulated A549 cells. CSE increased both survivin and Ki-67 expression and this effect was reverted by inhibition of the Notch-1 pathway. In conclusion, these data show that cigarette smoke may promote adenocarcinoma progression by activating the Notch-1 pathway thus supporting its role as hallmark of lung cancer progression and as a new target for lung cancer treatment.

Introduction Recently, transcatheter aortic valve replacement (TAVR) has emerged as established standard treatment for symptomatic severe aortic stenosis, providing an effective, less-invasive alternative to open cardiac surgery for inoperable or high-risk older patients. Evidence acquisition In order to assess the anticipated benefit of aortic replacement, considerable interest now lies in better identifying factors likely to predict outcome. In the elderly population frailty and medical comorbidities have been shown to significantly predict mortality, functional recovery and quality of life after transcatheter aortic valve replacement. Scientific literature focused on the three items will be discussed. Evidence synthesis High likelihood of futility is described in patients with severe chronic lung, kidney, liver disease and/or frailty. The addition of frailty components to conventional risk prediction has been shown to result in improved discrimination for death and disability following the procedure and identifies those individuals least likely to derive benefit. Several dedicated risk score have been proposed to provide new insights into predicted "futile" outcome. However, assessment of frailty according to a limited number of variables is not sufficient, while a multi-dimensional geriatric assessment significantly improves risk prediction. Conclusions A multidisciplinary heart team that includes geriatricians can allow the customization of therapeutic interventions in elderly patients to optimise care and avoid futility.

Notch-1 pathway plays an important role in lung carcinoma in the stem cell regulation, cellular communication, growth and differentiation. Cigarette smoke has an important role in Notch signaling activation in lung cancer. However, current data regarding the impact of cigarette smoke on the Notch pathway in lung cancer progression are limited. The present study was aimed at exploring whether cigarette smoke exposure altered the expression of Notch1 pathway by ex-vivo (surgical samples of lung parenchyma from smoker and non smoker patients with lung adenocarcinoma) and in vitro (adenocarcinoma A549 cell line) approaches. The expression of Notch1 and its ligand Jagged-1 in surgical samples was evaluated by immunohistochemistry. For the in vitro study, A549 were exposed to cigarette smoke extracts (CSE 2.5% and 5% for 6, 24 and 48 h) and the expression of Notch1, Jagged-1 and Hes-1 was evaluated by Real Time PCR and Western Blot (nuclear and cytoplasmic fractions). Expression and localization of Hes1 was also assessed by confocal microscopy. Higher expression of Notch-1 and Jagged-1 were observed in Smokers compared with non-Smokers. In A549, CSE exposure increased Notch-1, Jagged-1 and Hes-1 mRNA and protein levels. Confocal microscopy further confirmed higher expression of Hes-1 in the nuclei of cigarette smoke stimulated A549 cells. In conclusion, these data show that cigarette smoke may promote the activation of Notch1 pathway, corroborating its role as future hallmark of lung cancer progression and as a new target for lung cancer treatment.

Anaplastic thyroid carcinoma (ATC) is a rare and aggressive malignancy that accounts for the majority of deaths from all thyroid cancers. ATC exhibits invasiveness and highly resistance to conventional therapies which include cytotoxic chemotherapy, the combination of BRAF and MEK inhibition and, more recently, immunotherapies, that have shown promising but still limited results. A growing knowledge on ATC tumor biology is needed for developing more effective therapies with significant better survival. Researchers have begun to utilize 3D models to culture cancer cells for in vitro studies. In this work, C643 ATC cell line was cultured on polymeric scaffolds with high-interconnected porous matrix. They exhibited distinct viability, proliferation and 3D morphology similar to an in vivo solid tumor mass. We also carried out quantitative real-time PCR experiments for monitoring Cancer Stem Cells enrichment, since they are most probably the cause of tumor resistance, reoccurrence and metastasis. The same tests were performed after cell treatment with the chemotherapic Doxorubicin. An up-regulation of the analyzed stem-cell markers confirmed the high resistance to treatment of these cell line with respect to conventional drugs. In conclusion, 3D scaffolds could be an ideal platform for studying the mechanisms that regulate ACT growth and survival and also improving novel therapeutic approaches for treatment-resistant thyroid cancer.

Single-cell microarrays are emerging tools to unravel intrinsic diversity within complex cell populations, opening up new approaches for the in-depth understanding of highly relevant diseases. However, most of the current methods for their fabrication are based on cumbersome patterning approaches, employing organic solvents and/or expensive materials. Here, we demonstrate an unprecedented green-chemistry strategy to produce single-cell capture biochips onto glass surfaces by all-aqueous inkjet printing. At first, a chitosan film is easily inkjet printed and immobilized onto hydroxyl-rich glass surfaces by electrostatic immobilization. In turn, poly(ethylene glycol) diglycidyl ether is grafted on the chitosan film to expose reactive epoxy groups and induce antifouling properties. Subsequently, microscale collagen spots are printed onto the above surface to define the attachment area for single adherent human cancer cells harvesting with high yield. The reported inkjet printing approach enables one to modulate the collagen area available for cell attachment in order to control the number of captured cells per spot, from single-cells up to double- and multiple-cell arrays. Proof-of-principle of the approach includes pharmacological treatment of single-cells by the model drug doxorubicin. The herein presented strategy for single-cell array fabrication can constitute a first step toward an innovative and environmentally friendly generation of aqueous-based inkjet-printed cellular devices.

Prostate cancer (PCa) is the most common cancer in men. Nowadays, it is diagnosed through the test of serum prostate-specific antigen (PSA) and rectal examination; however, there is still debate about the PSA-based diagnosis. Seminal fluid (SF), contains a high concentration of subcellular lipid-bound microparticles, traditionally termed "prostasomes", that are extracellular vesicles (EVs) released into the extracellular space by prostate gland's epithelial cells. These vesicles, first described in 1982 promote motility of sperm cells, regulation of sperm cell capacitation, acrosome reaction and immune suppression within the female reproductive tract. It was demonstrated that prostasomes could contain PCa specific molecular fingerprints that can represent the status of their parental cells. Until now the analysis of isolated prostasomes released by PCa cells has proved several advantages compared to the analysis of parental cells. Moreover, the molecular composition of prostasomes could reflect their capacity to influence PCa growth and metastasis. In this review, we discuss the role of prostasomes in PCa, focusing in the possibility of exosomes to represent a non-invasive test for PCa diagnosis and as a possible agent for enhance the sexual transmission diseases (STD) through immunomodulation.

Identification of thyroid stem cells in the past few years has made important contributions to our understanding of the cellular and molecular mechanisms that induce tissue regeneration and repair. Embryonic stem (ES) cells and induced-pluripotent stem cells have been used to establish reliable protocols to obtain mature thyrocytes and functional follicles for the treatment of thyroid diseases in mice. In addition, the discovery of resident thyroid progenitor cells, along with other sources of stem cells, has defined in detail the mechanisms responsible for tissue repair upon moderate or severe organ injury.In this chapter, we highlight in detail the current state of research on thyroid stem cells by focusing on (1) the description of the first experiments performed to obtain thyroid follicles from embryonic stem cells, (2) the identification of resident stem cells in the thyroid gland, and (3) the definition of the current translational in vivo and in vitro models used for thyroid tissue repair and regeneration.

Identification of thyroid stem cells in the past few years has made important contributions to our understanding of the cellular and molecular mechanisms that induce tissue regeneration and repair. Embryonic stem (ES) cells and induced-pluripotent stem cells have been used to establish reliable protocols to obtain mature thyrocytes and functional follicles for the treatment of thyroid diseases in mice. In addition, the discovery of resident thyroid progenitor cells, along with other sources of stem cells, has defined in detail the mechanisms responsible for tissue repair upon moderate or severe organ injury.In this chapter, we highlight in detail the current state of research on thyroid stem cells by focusing on (1) the description of the first experiments performed to obtain thyroid follicles from embryonic stem cells, (2) the identification of resident stem cells in the thyroid gland, and (3) the definition of the current translational in vivo and in vitro models used for thyroid tissue repair and regeneration.

Mesenchymal stromal/stem cells (MSCs) are multipotent adult stem cells that support homeostasis during tissue regeneration. In the last decade, cell therapies based on the use of MSCs have emerged as a promising strategy in the field of regenerative medicine. Although these cells possess robust therapeutic properties that can be applied in the treatment of different diseases, variables in preclinical and clinical trials lead to inconsistent outcomes. MSC therapeutic effects result from the secretion of bioactive molecules affected by either local microenvironment or MSC culture conditions. Hence, MSC paracrine action is currently being explored in several clinical settings either using a conditioned medium (CM) or MSC-derived exosomes (EXOs), where these products modulate tissue responses in different types of injuries. In this scenario, MSC paracrine mechanisms provide a promising framework for enhancing MSC therapeutic benefits, where the composition of secretome can be modulated by priming of the MSCs. In this review, we examine the literature on the priming of MSCs as a tool to enhance their therapeutic properties applicable to the main processes involved in tissue regeneration, including the reduction of fibrosis, the immunomodulation, the stimulation of angiogenesis, and the stimulation of resident progenitor cells, thereby providing new insights for the therapeutic use of MSCs-derived products.

The NLRP3 inflammasome is a multi-protein complex that initiates innate immunity responses when exposed to a wide range of stimuli, including pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs). Inflammasome activation leads to the release of the pro-inflammatory cytokines interleukin (IL)-1β and IL-18 and to pyroptotic cell death. Over-activation of NLRP3 inflammasome has been associated with several chronic inflammatory diseases. A deep knowledge of NLRP3 inflammasome biology is required to better exploit its potential as therapeutic target and for the development of new selective drugs. To this purpose, in the past few years, several tools have been developed for the biological characterization of the multimeric inflammasome complex, the identification of the upstream signaling cascade leading to inflammasome activation, and the downstream effects triggered by NLRP3 activation. In this review, we will report cellular models and cellular, biochemical, and biophysical assays that are currently available for studying inflammasome biology. A special focus will be on those models/assays that have been used to identify NLRP3 inhibitors and their mechanism of action.

Biomedical imaging in recent decades has clarified our understanding of normal and pathological cellular processes in vivo. In particular, this approach recently provided insights into processes occurring at a molecular or genetic level rather than at the anatomical level. The evolution of this discipline by engineering have led to its integration into biomedical research to (1) increase sensitivity and resolution imaging and to (2) improve tissue and cell specificity. Currently, imaging approaches are used in three different biomedical areas: (a) identification of cellular processes in physiological and disease state; (b) in vivo single-cell imaging; and (c) identification of new prognostic and therapeutical strategies. In this review, we will focus on the state of art of biomedical imaging in cancer. Specifically, we will highlight the most important advances in imaging tools available for basic and translational cancer research, with a particular emphasis on solid tissue malignancies.Immunology and Cell Biology advance online publication, 4 April 2017; doi:10.1038/icb.2017.17.

A fundamental task in cancer research aims at the identification of new pharmacological therapies that can affect tumor growth. Differentiation therapy might exploit this function not only for hematological diseases, such as acute promyelocytic leukemia (APML) but also for epithelial tumors, including lung cancer. Here we show that Retinoic Acid (RA) arrests in vitro and in vivo the growth of Tyrosine Kinase Inhibitors (TKI) resistant Non Small Cell Lung Cancer (NSCLC). In particular, we found that RA induces G0/G1 cell cycle arrest in TKI resistant NSCLC cells and activates terminal differentiation programs by modulating the expression of GATA6, a key transcription factor involved in the physiological differentiation of the distal lung. In addition, our results demonstrate that RA inhibits EGFR and Wnt signaling activation, two pathways involved in NSCLC progression. Furthermore, we uncovered a novel mechanism in NSCLC that shows how RA exerts its function; we found that RA-mediated GATA6 activation is necessary for EGFR and Wnt inhibition, thus leading to 1) increased differentiation and 2) loss of proliferation. All together, these findings prove that differentiation therapy might be feasible in TKI resistant NSCLCs, and shed light on new targets to define new pharmacological therapies.

Coordinated Hair Growth Wnt/β-catenin signaling is a key pathway that plays a conserved role in regulating stem cell function during adult tissue regeneration. Using time-lapse imaging of live mice, Deschene et al. (p. 1353 ) show that genetic activation of β-catenin within hair follicle stem cells generates axes of hair growth by coordinated cell divisions and cell movements, even when the normal niches—the dermal papillae—are laser-ablated. Activated β-catenin enhances Wnt ligand secretion, and these ligands can then activate Wnt signaling in adjacent cells that do not have activated β-catenin, indicating how activated stem cells could influence neighboring cells during normal growth and in cancer.

Tissue development and regeneration depend on cell-cell interactions and signals that target stem cells and their immediate progeny. However, the cellular behaviours that lead to a properly regenerated tissue are not well understood. Using a new, non-invasive, intravital two-photon imaging approach we study physiological hair-follicle regeneration over time in live mice. By these means we have monitored the behaviour of epithelial stem cells and their progeny during physiological hair regeneration and addressed how the mesenchyme influences their behaviour. Consistent with earlier studies, stem cells are quiescent during the initial stages of hair regeneration, whereas the progeny are more actively dividing. Moreover, stem cell progeny divisions are spatially organized within follicles. In addition to cell divisions, coordinated cell movements of the progeny allow the rapid expansion of the hair follicle. Finally, we show the requirement of the mesenchyme for hair regeneration through targeted cell ablation and long-term tracking of live hair follicles. Thus, we have established an in vivo approach that has led to the direct observation of cellular mechanisms of growth regulation within the hair follicle and that has enabled us to precisely investigate functional requirements of hair-follicle components during the process of physiological regeneration. © 2012 Macmillan Publishers Limited. All rights reserved.

The New York Stem Cell Foundation's "Sixth Annual Translational Stem Cell Research Conference" convened on October 11-12, 2011 at the Rockefeller University in New York City. Over 450 scientists, patient advocates, and stem cell research supporters from 14 countries registered for the conference. In addition to poster and platform presentations, the conference featured panels entitled "Road to the Clinic" and "The Future of Regenerative Medicine."

Stem cells might provide unlimited supply of transplantable cells for β-cell replacement therapy in diabetes. The human limbus is a highly specialized region hosting a well-recognized population of epithelial stem cells, which sustain the continuous renewal of the cornea, and the recently identified stromal fibroblast-like stem cells (f-LSCs), with apparent broader plasticity. However, the lack of specific molecular markers for the identification of the multipotent limbal subpopulation has so far limited the investigation of their differentiation potential. In this study we show that the human limbus contains uncommitted cells that could be potentially harnessed for the treatment of diabetes. Fourteen limbal biopsies were obtained from patients undergoing surgery for ocular diseases not involving the conjunctiva or corneal surface. We identified a subpopulation of f-LSCs characterized by robust proliferative capacity, expressing several pluripotent stem cell markers and exhibiting self-renewal ability. We then demonstrated the potential of f-LSCs to differentiate in vitro into functional insulin-secreting cells by developing a four-step differentiation protocol that efficiently directed f-LSCs towards the pancreatic endocrine cell fate. The expression of specific endodermal, pancreatic, islet, and β-cell markers, as well as functional properties of f-LSC-derived insulin-producing cells, were evaluated during differentiation. With our stage-specific approach, up to 77% of f-LSCs eventually differentiated into cells expressing insulin (also assessed as C-peptide) and exhibited phenotypic features of mature β-cells, such as expression of critical transcription factors and presence of secretory granules. Although insulin content was about 160-fold lower than what observed in adult islets, differentiated cells processed ~98% of their proinsulin content, similar to mature β-cells. Moreover, they responded in vitro in a regulated manner to multiple secretory stimuli, including glucose. In conclusion, f-LSCs represent a possible relevant source of autologous, transplantable, insulin-producing cells that could be tested for the reversal of diabetes.

Hypoxia-inducible factor-1α is found frequently overexpressed in solid tumors cells, exerting an important role in angiogenesis, glucose metabolism, cell proliferation, survival and invasion. In thyroid carcinomas, hypoxia-inducible factor-1α expression was found increased in differentiated, poorly differentiated, medullary and anaplastic variants. Hypoxia represents the principal stimulus responsible for hypoxia-inducible factor-1α induction. Other nonhypoxic stimuli increase hypoxia-inducible factor-1α synthesis through the activation of phosphatidylinositol 3-kinase and mitogen-activated protein kinase pathways in a cell-type-specific manner. We have previously shown the role of BRAFV600E mutation in papillary thyroid cancer cells as a factor that facilitates tumor cell growth and progression. In this study, we tested the hypothesis that BRAFV600E mutation influences hypoxia-inducible factor-1α expression in papillary thyroid carcinoma cells. We analyzed 27 papillary thyroid carcinomas, 13 of which presented BRAFV600E mutation. In tumor tissues, immunoreactivity for hypoxia-inducible factor-1α was detected in the majority of analyzed BRAFV600E mutated cases. Transcriptional analyses revealed elevated hypoxia-inducible factor-1α levels with significant differences between wild-type and mutated group. A BRAF wild-type papillary thyroid carcinoma cell line and a BRAFV600E mutated papillary thyroid carcinoma cell line were selected to study the effects of BRAF mutation on hypoxia-inducible factor-1α expression in vitro. Knockdown of mutant BRAFV600E or both the wild type and the BRAFV600E by RNA interference induced a significant reduction of hypoxia-inducible factor-1α expression at mRNA and protein levels. Pharmacological inhibition of BRAF significantly reduces hypoxia-inducible factor-1α expression levels in papillary thyroid carcinoma cell line harboring BRAFV600E mutation. Our results suggest that hypoxia-inducible factor-1α is expressed in papillary thyroid carcinomas and is regulated not only by hypoxia but also by BRAFV600E-mediated signaling pathway.

Tissue homeostasis is achieved through a balance of cell production (growth) and elimination (regression). In contrast to tissue growth, the cells and molecular signals required for tissue regression remain unknown. To investigate physiological tissue regression, we use the mouse hair follicle, which cycles stereotypically between phases of growth and regression while maintaining a pool of stem cells to perpetuate tissue regeneration. Here we show by intravital microscopy in live mice that the regression phase eliminates the majority of the epithelial cells by two distinct mechanisms: terminal differentiation of suprabasal cells and a spatial gradient of apoptosis of basal cells. Furthermore, we demonstrate that basal epithelial cells collectively act as phagocytes to clear dying epithelial neighbours. Through cellular and genetic ablation we show that epithelial cell death is extrinsically induced through transforming growth factor (TGF)-β activation and mesenchymal crosstalk. Strikingly, our data show that regression acts to reduce the stem cell pool, as inhibition of regression results in excess basal epithelial cells with regenerative abilities. This study identifies the cellular behaviours and molecular mechanisms of regression that counterbalance growth to maintain tissue homeostasis.

A fundamental goal in cancer biology is to identify the cells and signalling pathways that are keys to induce tumour regression. Here we use a spontaneously self-regressing tumour, cutaneous keratoacanthoma (KAs), to identify physiological mechanisms that drive tumour regression. By using a mouse model system that recapitulates the behaviour of human KAs, we show that self-regressing tumours shift their balance to a differentiation programme during regression. Furthermore, we demonstrate that developmental programs utilized for skin hair follicle regeneration, such as Wnt, are hijacked to sustain tumour growth and that the retinoic acid (RA) signalling pathway promotes tumour regression by inhibiting Wnt signalling. Finally, we find that RA signalling can induce regression of malignant tumours that do not normally spontaneously regress, such as squamous cell carcinomas. These findings provide new insights into the physiological mechanisms of tumour regression and suggest therapeutic strategies to induce tumour regression., Keratoacanthomas are skin tumours that spontaneously regress but the mechanisms leading to regression are unknown. Here, using a mouse chemical carcinogenesis model, the authors show that tumour regression is driven by activation of retinoic acid signalling that induces Wnt inhibition and tumour differentiation.

BRAFV600E is the most common mutation found in papillary thyroid carcinoma (PTC). Tissue inhibitor of metalloproteinases (TIMP-1) and nuclear factor (NF)-κB have been shown to play an important role in thyroid cancer. In particular, TIMP-1 binds its receptor CD63 on cell surface membrane and activates Akt signaling pathway, which is eventually responsible for its anti-apoptotic activity. The aim of our study was to evaluate whether interplay among these three factors exists and exerts a functional role in PTCs. To this purpose, 56 PTC specimens were analyzed for BRAFV600E mutation, TIMP-1 expression, and NF-κB activation. We found that BRAFV600E mutation occurs selectively in PTC nodules and is associated with hyperactivation of NF-κB and upregulation of both TIMP-1 and its receptor CD63. To assess the functional relationship among these factors, we first silenced BRAF gene in BCPAP cells, harboring BRAFV600E mutation. We found that silencing causes a marked decrease in TIMP-1 expression and NF-κB binding activity, as well as decreased invasiveness. After treatment with specific inhibitors of MAPK pathway, we found that only sorafenib was able to increase IκB-α and reduce both TIMP-1 expression and Akt phosphorylation in BCPAP cells, indicating that BRAFV600E activates NF-κB and this pathway is MEK-independent. Taken together, our findings demonstrate that BRAFV600E causes upregulation of TIMP-1 via NF-κB. TIMP-1 binds then its surface receptor CD63, leading eventually to Akt activation, which in turn confers antiapoptotic behavior and promotion of cell invasion. The recognition of this functional trilogy provides insight on how BRAFV600E determines cancer initiation, progression, and invasiveness in PTC, also identifying new therapeutic targets for the treatment of highly aggressive forms.