p38MAPK plays a crucial role in stromal-mediated tumorigenesis

Immune Aging and Immunotherapy in Cancer

Immune functions decline as we age, while the incidence of cancer rises. The advent of immune checkpoint blockade (ICB) has not only revolutionized cancer therapy, but also spawned great interest in identifying predictive biomarkers, since only one third of patients show treatment response. The aging process extensively affects the adaptive immune system and thus T cells, which are the main target of ICB. In this review, we address age-related changes regarding the adaptive immune system with a focus on T cells and their implication on carcinogenesis and ICB. Differences between senescence, exhaustion, and anergy are defined and current knowledge, treatment strategies, and studies exploring T cell aging as a biomarker for ICB are discussed. Finally, novel approaches to improve immunotherapies and to identify biomarkers of response to ICB are presented and their potential is assessed in a comparative analysis.

Inflammation, epigenetics, and metabolism converge to cell senescence and ageing: the regulation and intervention

Remarkable progress in ageing research has been achieved over the past decades. General perceptions and experimental evidence pinpoint that the decline of physical function often initiates by cell senescence and organ ageing. Epigenetic dynamics and immunometabolic reprogramming link to the alterations of cellular response to intrinsic and extrinsic stimuli, representing current hotspots as they not only (re-)shape the individual cell identity, but also involve in cell fate decision. This review focuses on the present findings and emerging concepts in epigenetic, inflammatory, and metabolic regulations and the consequences of the ageing process. Potential therapeutic interventions targeting cell senescence and regulatory mechanisms, using state-of-the-art techniques are also discussed.

Overcoming the senescence-associated secretory phenotype (SASP): a complex mechanism of resistance in the treatment of cancer

Senescence is a cellular state in which cells undergo persistent cell cycle arrest in response to nonlethal stress. In the treatment of cancer, senescence induction is a potent method of suppressing tumour cell proliferation. In spite of this, senescent cancer cells and adjacent nontransformed cells of the tumour microenvironment can remain metabolically active, resulting in paradoxical secretion of pro-inflammatory factors, collectively termed the senescence-associated secretory phenotype (SASP). The SASP plays a critical role in tumorigenesis, affecting numerous processes including invasion, metastasis, epithelial-to-mesenchymal transition (EMT) induction, therapy resistance and immunosuppression. With increasing evidence, it is becoming clear that cell type, tissue of origin and the primary cellular stressor are key determinants in how the SASP will influence tumour development and progression, including whether it will be pro- or antitumorigenic. In this review, we will focus on recent evidence regarding therapy-induced senescence (TIS) from anticancer agents, including chemotherapy, radiation, immunotherapy, and targeted therapies, and how each therapy can trigger the SASP, which in turn influences treatment efficacy. We will also discuss novel pharmacological manipulation of senescent cancer cells and the SASP, which offers an exciting and contemporary approach to cancer therapeutics. With future research, these adjuvant options may help to mitigate many of the negative side effects and protumorigenic roles that are currently associated with TIS in cancer.

Exosomes Derived from the Human Primary Colorectal Cancer Cell Line SW480 Orchestrate Fibroblast-Led Cancer Invasion

In localized tumors, basement membrane (BM) prevents invasive outgrowth of tumor cells into surrounding tissues. When carcinomas become invasive, cancer cells either degrade BM or reprogram stromal fibroblasts to breach BM barrier and lead invasion of cancer cells into surrounding tissues in a process called fibroblast-led invasion. However, tumor-derived factors orchestrating fibroblast-led invasion remain poorly understood. Here it is shown that although early-stage primary colorectal adenocarcinoma (SW480) cells are themselves unable to invade Matrigel matrix, they secrete exosomes that reprogram normal fibroblasts to acquire de novo capacity to invade matrix and lead invasion of SW480 cells. Strikingly, cancer cells follow leading fibroblasts as collective epithelial-clusters, thereby circumventing need for epithelial to mesenchymal transition, a key event associated with invasion. Moreover, acquisition of pro-invasive phenotype by fibroblasts treated with SW480-derived exosomes relied on exosome-mediated MAPK pathway activation. Mass spectrometry-based protein profiling reveals that cancer exosomes upregulate fibroblasts proteins implicated in focal adhesion (ITGA2/A6/AV, ITGB1/B4/B5, EGFR, CRK), regulators of actin cytoskeleton (RAC1, ARF1, ARPC3, CYFIP1, NCKAP1, ICAM1, ERM complex), and signalling pathways (MAPK, Rap1, RAC1, Ras) important in pro-invasive remodeling of extracellular matrix. Blocking tumor exosome-mediated signaling to fibroblasts therefore represents an attractive therapeutic strategy in restraining tumors by perturbing stroma-driven invasive outgrowth.

Role of MicroRNA-145 in DNA Damage Signalling and Senescence in Vascular Smooth Muscle Cells of Type 2 Diabetic Patients

Increased cardiovascular morbidity and mortality in individuals with type 2 diabetes (T2DM) is a significant clinical problem. Despite advancements in achieving good glycaemic control, this patient population remains susceptible to macrovascular complications. We previously discovered that vascular smooth muscle cells (SMC) cultured from T2DM patients exhibit persistent phenotypic aberrancies distinct from those of individuals without a diagnosis of T2DM. Notably, persistently elevated expression levels of microRNA-145 co-exist with characteristics consistent with aging, DNA damage and senescence. We hypothesised that increased expression of microRNA-145 plays a functional role in DNA damage signalling and subsequent cellular senescence specifically in SMC cultured from the vasculature of T2DM patients. In this study, markers of DNA damage and senescence were unambiguously and permanently elevated in native T2DM versus non-diabetic (ND)-SMC. Exposure of ND cells to the DNA-damaging agent etoposide inflicted a senescent phenotype, increased expression of apical kinases of the DNA damage pathway and elevated expression levels of microRNA-145. Overexpression of microRNA-145 in ND-SMC revealed evidence of functional links between them; notably increased secretion of senescence-associated cytokines and chronic activation of stress-activated intracellular signalling pathways, particularly the mitogen-activated protein kinase, p38α. Exposure to conditioned media from microRNA-145 overexpressing cells resulted in chronic p38α signalling in naïve cells, evidencing a paracrine induction and reinforcement of cell senescence. We conclude that targeting of microRNA-145 may provide a route to novel interventions to eliminate DNA-damaged and senescent cells in the vasculature and to this end further detailed studies are warranted.

mTOR as a senescence manipulation target: A forked road

Cellular senescence, cancer and aging are highly interconnected. Among many important molecular machines that lie at the intersection of this triad, the mechanistic (formerly mammalian) target of rapamycin (mTOR) is a central regulator of cell metabolism, proliferation, and survival. The mTOR signaling cascade is essential to maintain cellular homeostasis in normal biological processes or in response to stress, and its dysregulation is implicated in the progression of many disorders, including age-associated diseases. Accordingly, the pharmacological implications of mTOR inhibition using rapamycin or others rapalogs span the treatment of various human diseases from immune disorders to cancer. Importantly, rapamycin is one of the only known pan-species drugs that can extend lifespan. The molecular and cellular mechanisms explaining the phenotypic consequences of mTOR are vast and heavily studied. In this review, we will focus on the potential role of mTOR in the context of cellular senescence, a tumor suppressor mechanism and a pillar of aging. We will explore the link between senescence, autophagy and mTOR and discuss the opportunities to exploit senescence-associated mTOR functions to manipulate senescence phenotypes in age-associated diseases and cancer treatment.

Netrin G1 Promotes Pancreatic Tumorigenesis through Cancer-Associated Fibroblast-Driven Nutritional Support and Immunosuppression

Pancreatic ductal adenocarcinoma (PDAC) has a poor 5-year survival rate and lacks effective therapeutics. Therefore, it is of paramount importance to identify new targets. Using multiplex data from patient tissue, three-dimensional coculturing in vitro assays, and orthotopic murine models, we identified Netrin G1 (NetG1) as a promoter of PDAC tumorigenesis. We found that NetG1+ cancer-associated fibroblasts (CAF) support PDAC survival, through a NetG1-mediated effect on glutamate/glutamine metabolism. Also, NetG1+ CAFs are intrinsically immunosuppressive and inhibit natural killer cell-mediated killing of tumor cells. These protumor functions are controlled by a signaling circuit downstream of NetG1, which is comprised of AKT/4E-BP1, p38/FRA1, vesicular glutamate transporter 1, and glutamine synthetase. Finally, blocking NetG1 with a neutralizing antibody stunts in vivo tumorigenesis, suggesting NetG1 as potential target in PDAC. SIGNIFICANCE: This study demonstrates the feasibility of targeting a fibroblastic protein, NetG1, which can limit PDAC tumorigenesis in vivo by reverting the protumorigenic properties of CAFs. Moreover, inhibition of metabolic proteins in CAFs altered their immunosuppressive capacity, linking metabolism with immunomodulatory function.See related commentary by Sherman, p. 230.This article is highlighted in the In This Issue feature, p. 211.

Diversity and versatility of p38 kinase signalling in health and disease

The ability of cells to deal with different types of stressful situations in a precise and coordinated manner is key for survival and involves various signalling networks. Over the past 25 years, p38 kinases — in particular, p38α — have been implicated in the cellular response to stress at many levels. These span from environmental and intracellular stresses, such as hyperosmolarity, oxidative stress or DNA damage, to physiological situations that involve important cellular changes such as differentiation. Given that p38α controls a plethora of functions, dysregulation of this pathway has been linked to diseases such as inflammation, immune disorders or cancer, suggesting the possibility that targeting p38α could be of therapeutic interest. In this Review, we discuss the organization of this signalling pathway focusing on the diversity of p38α substrates, their mechanisms and their links to particular cellular functions. We then address how the different cellular responses can be generated depending on the signal received and the cell type, and highlight the roles of this kinase in human physiology and in pathological contexts.

p38α — the best-characterized member of the p38 kinase family — is a key mediator of cellular stress responses. p38α is activated by a plethora of signals and functions through a multitude of substrates to regulate different cellular behaviours. Understanding context-dependent p38α signalling provides important insights into p38α roles in physiology and pathology.

The Jekyll and Hyde of Cellular Senescence in Cancer

Cellular senescence is a state of stable cell cycle arrest that can be triggered in response to various insults and is characterized by distinct morphological hallmarks, gene expression profiles, and the senescence-associated secretory phenotype (SASP). Importantly, cellular senescence is a key component of normal physiology with tumor suppressive functions. In the last few decades, novel cancer treatment strategies exploiting pro-senescence therapies have attracted considerable interest. Recent insight, however, suggests that therapy-induced senescence (TIS) elicits cell-autonomous and non-cell-autonomous implications that potentially entail detrimental consequences, reflecting the Jekyll and Hyde nature of cancer cell senescence. In essence, the undesirable manifestations that generally culminate in inflammation, cancer stemness, senescence reversal, therapy resistance, and disease recurrence are dictated by the persistent accumulation of senescent cells and the SASP. Thus, mitigating these pro-tumorigenic effects by eliminating these cells or inhibiting their SASP production holds great promise for developing innovative therapeutic strategies. In this review, we describe the fundamental aspects and dynamics of cancer cell senescence and summarize the comprehensive research on the adverse outcomes of TIS. Furthermore, we underline the rationale and motivation of emerging senotherapeutic modalities surrounding the removal of senescent cells and the SASP to help maximize the overall efficacy of cancer therapies.

Implication of cellular senescence in the progression of chronic kidney disease and the treatment potencies

Chronic kidney disease (CKD) is an increasing major public health problem worldwide. And CKD shares numerous phenotypic similarities with kidney as well as systemic ageing. Cellular senescence is mainly characterized by a stable cell cycle arrest, senescence-associated secretory phenotype (SASP) and senescent cell anti-apoptotic pathways (SCAPs). Herein, the regulations and the internal mechanisms of cellular senescence will be discussed. Meanwhile, efforts are made to give a comprehensive overview of the recent advances of the implication of cellular senescence in CKD. To date, numerous studies have focused on the effects of ageing risk factors in kidney and thereby trying to interrupt the kidney ageing processes with senolytics. Interestingly, some of them showed enormous clinical application potentials. Therefore, senotherapeutics can be applied as novel potential strategies for the treatment of CKD.

Malignancy and IFITM3: Friend or Foe?

The prevalence and incidence of cancers has risen over the last decade. Available treatments have improved outcomes, yet mortality and morbidity remain high, creating an urgent demand for personalized and new therapy targets. Interferon induced transmembrane protein (IFITM3) is highly expressed in cancers and is a marker of poor prognosis. In this review, we discuss recent advances in IFITM3 biology, the regulatory pathways, and its function within cancer as part of immunity and maintaining stemness. Overexpression of IFITM3 is likely an indirect effect of ongoing inflammation, immune and cancer epithelial-to-mesenchymal (EMT) related pathways i.e., interferons, TGF-β, WNT/β-catenin, etc. However, IFITM3 also influences tumorigenic phenotypes, such as cell proliferation, migration and invasion. Furthermore, IFITM3 plays a key role in cancer growth and maintenance. Silencing of IFITM3 reduces these phenotypes. Therefore, targeting of IFITM3 will likely have implications for potential cancer therapies.

Blockade of p38 kinase impedes the mobilization of protumorigenic myeloid populations to impact breast cancer metastasis

Patients with metastatic breast cancer (MBC) have limited therapeutic options and novel treatments are critically needed. Prior research implicates tumor-induced mobilization of myeloid cell populations in metastatic progression, as well as being an unfavorable outcome in MBC; however, the underlying mechanisms for these relationships remain unknown. Here, we provide evidence for a novel mechanism by which p38 promotes metastasis. Using triple-negative breast cancer models, we showed that a selective inhibitor of p38 (p38i) significantly reduced tumor growth, angiogenesis, and lung metastasis. Importantly, p38i decreased the accumulation of myeloid populations, namely, myeloid-derived suppressor cells (MDSCs) and CD163+ tumor-associated macrophages (TAMs). p38 controlled the expression of tumor-derived chemokines/cytokines that facilitated the recruitment of protumor myeloid populations. Depletion of MDSCs was accompanied by reduced TAM infiltration and phenocopied the antimetastatic effects of p38i. Reciprocally, p38i increased tumor infiltration by cytotoxic CD8+ T cells. Furthermore, the CD163+ /CD8+ expression ratio inversely correlated with metastasis-free survival in breast cancer, suggesting that targeting p38 may improve clinical outcomes. Overall, our study highlights a previously unknown p38-driven pathway as a therapeutic target in MBC.

Deconstructing tumor heterogeneity: the stromal perspective

Significant advances have been made towards understanding the role of immune cell-tumor interplay in either suppressing or promoting tumor growth, progression, and recurrence, however, the roles of additional stromal elements, cell types and/or cell states remain ill-defined. The overarching goal of this NCI-sponsored workshop was to highlight and integrate the critical functions of non-immune stromal components in regulating tumor heterogeneity and its impact on tumor initiation, progression, and resistance to therapy. The workshop explored the opposing roles of tumor supportive versus suppressive stroma and how cellular composition and function may be altered during disease progression. It also highlighted microenvironment-centered mechanisms dictating indolence or aggressiveness of early lesions and how spatial geography impacts stromal attributes and function. The prognostic and therapeutic implications as well as potential vulnerabilities within the heterogeneous tumor microenvironment were also discussed. These broad topics were included in this workshop as an effort to identify current challenges and knowledge gaps in the field.

Non-canonical ATM/MRN activities temporally define the senescence secretory program

Senescent cells display senescence-associated (SA) phenotypic programs such as stable proliferation arrest (SAPA) and a secretory phenotype (SASP). Senescence-inducing persistent DNA double-strand breaks (pDSBs) cause an immediate DNA damage response (DDR) and SAPA, but the SASP requires days to develop. Here, we show that following the immediate canonical DDR, a delayed chromatin accumulation of the ATM and MRN complexes coincides with the expression of SASP factors. Importantly, histone deacetylase inhibitors (HDACi) trigger SAPA and SASP in the absence of DNA damage. However, HDACi-induced SASP also requires ATM/MRN activities and causes their accumulation on chromatin, revealing a DNA damage-independent, non-canonical DDR activity that underlies SASP maturation. This non-canonical DDR is required for the recruitment of the transcription factor NF-κB on chromatin but not for its nuclear translocation. Non-canonical DDR further does not require ATM kinase activity, suggesting structural ATM functions. We propose that delayed chromatin recruitment of SASP modulators is the result of non-canonical DDR signaling that ensures SASP activation only in the context of senescence and not in response to transient DNA damage-induced proliferation arrest.

Micro-strains in the extracellular matrix induce angiogenesis

An improved understanding of biomechanical factors that control tumor development, including angiogenesis, could explain why few of the promising treatment strategies discovered via in vitro models translate well into in vivo or clinical studies. The ability to manipulate and in real-time study the multiple independent biomechanical properties on cellular activity has been limited, primarily due to limitations in traditional in vitro platforms or the inability to manipulate such factors in vivo. We present a novel microfluidic platform that mimics the vascularized tumor microenvironment with independent control of interstitial flow and mechanical strain. The microtissue platform design isolates mechanically-stimulated angiogenesis in the tumor microenvironment, by manipulating interstitial flow to eliminate soluble factors that could drive blood vessel growth. Our studies demonstrate that enhanced mechanical strain induced by cancer-associated fibroblasts (CAFs) promotes angiogenesis in microvasculature models, even when preventing diffusion of soluble factors to the growing vasculature. Moreover, small but significant decreases in micro-strains induced by inhibited CAFs were sufficient to reduce angiogenesis. Ultimately, we believe this platform represents a significant advancement in the ability to investigate biomechanical signals while controlling for biochemical signals, with a potential to be utilized in fields beyond cancer research.

LGR5 in breast cancer and ductal carcinoma in situ: a diagnostic and prognostic biomarker and a therapeutic target

BACKGROUND

Novel biomarkers are required to discern between breast tumors that should be targeted for treatment from those that would never become clinically apparent and/or life threatening for patients. Moreover, therapeutics that specifically target breast cancer (BC) cells with tumor-initiating capacity to prevent recurrence are an unmet need. We investigated the clinical importance of LGR5 in BC and ductal carcinoma in situ (DCIS) to explore LGR5 as a biomarker and a therapeutic target.

METHODS

We stained BC (n = 401) and DCIS (n = 119) tissue microarrays with an antibody against LGR5. We examined an LGR5 knockdown ER^- cell line that was orthotopically transplanted and used for in vitro colony assays. We also determined the tumor-initiating role of Lgr5 in lineage-tracing experiments. Lastly, we transplanted ER^- patient-derived xenografts into mice that were subsequently treated with a LGR5 antibody drug conjugate (anti-LGR5-ADC).

RESULTS

LGR5 expression correlated with small tumor size, lower grade, lymph node negativity, and ER-positivity. ER⁺ patients with LGR5^high tumors rarely had recurrence, while high-grade ER^- patients with LGR5^high expression recurred and died due to BC more often. Intriguingly, all the DCIS patients who later died of BC had LGR5-positive tumors. Colony assays and xenograft experiments substantiated a role for LGR5 in ER^- tumor initiation and subsequent growth, which was further validated by lineage-tracing experiments in ER^- /triple-negative BC mouse models. Importantly, by utilizing LGR5^high patient-derived xenografts, we showed that anti-LGR5-ADC should be considered as a therapeutic for high-grade ER^- BC.

CONCLUSION

LGR5 has distinct roles in ER^- vs. ER⁺ BC with potential clinical applicability as a biomarker to identify patients in need of therapy and could serve as a therapeutic target for high-grade ER^- BC.

Activation of p38α stress-activated protein kinase drives the formation of the pre-metastatic niche in the lungs

Primary tumor-derived factors (TDFs) act upon normal cells to generate a pre-metastatic niche, which promotes colonization of target organs by disseminated malignant cells. Here we report that TDFs-induced activation of the p38α kinase in lung fibroblasts plays a critical role in the formation of a pre-metastatic niche in the lungs and subsequent pulmonary metastases. Activation of p38α led to inactivation of type I interferon signaling and stimulation of expression of fibroblast activation protein (FAP). FAP played a key role in remodeling of the extracellular matrix as well as inducing the expression of chemokines that enable lung infiltration by neutrophils. Increased activity of p38 in normal cells was associated with metastatic disease and poor prognosis in human melanoma patients whereas inactivation of p38 suppressed lung metastases. We discuss the p38α-driven mechanisms stimulating the metastatic processes and potential use of p38 inhibitors in adjuvant therapy of metastatic cancers.

GALC Triggers Tumorigenicity of Colorectal Cancer via Senescent Fibroblasts

Colorectal cancer (CRC)-associated senescent fibroblasts may play a crucial role in tumor progression, but the mechanism remains unclear. In order to solve this complicated problem, we randomly collected 16 patients with CRC, who had been treated with oxaliplatin and capecitabine (XELOX). Hematoxylin-eosin (HE) staining revealed that the tumor-stroma ratio (TSR) of CRC was affected by XELOX treatment. Immunohistochemistry (IHC) and senescence-associated β-galactosidase (SAβG) staining were used to verify a stable model of senescent fibroblasts. IHC analysis showed that high expression levels of galactosylceramidase (GALC) and significant senescence-associated β-galactosidase (SAβG) staining were associated with CRC patient survival. We observed that fibroblasts overexpressing GALC underwent cell cycle arrest. Changes in cell morphology and cell cycle characteristics were accompanied by the upregulation of the p16, p21, and p53 gene, and the downregulation of hTERT expression. In a co-culture system, fibroblasts overexpressing GALC significantly increased the proliferation of CRC cells. Transmission electron microscopy (TEM) analysis confirmed that GALC overexpression fibroblasts co-cultured with CRC caused changes in CRC cell morphology. The aging fibroblast co-culture group (70%) had a higher migration ability. In vivo experiments and transcriptomics analysis were performed to verify the effect of senescent fibroblasts on tumor formation and to identify the potential mechanisms for the above results. We found that a high expression of ATF3 was related to good survival rates. However, a high expression of KIAA0907 was bad for survival rates (p < 0.05). The knockdown of ATF3 can promote cell proliferation, migration, and clonogenic assays, while downregulation of KIAA0907 inhibits cell proliferation, migration, and clonogenic assays. The results demonstrate that senescent fibroblasts with a high level of GALC regulated several aspects of the tumor growth process, including migration and invasion.

Regulation of senescence traits by MAPKs

A phenotype of indefinite growth arrest acquired in response to sublethal damage, cellular senescence affects normal aging and age-related disease. Mitogen-activated protein kinases (MAPKs) are capable of sensing changes in cellular conditions, and in turn elicit adaptive responses including cell senescence. MAPKs modulate the levels and function of many proteins, including proinflammatory factors and factors in the p21/p53 and p16/RB pathways, the main senescence-regulatory axes. Through these actions, MAPKs implement key traits of senescence-growth arrest, cell survival, and the senescence-associated secretory phenotype (SASP). In this review, we summarize and discuss our current knowledge of the impact of MAPKs in senescence. In addition, given that eliminating or suppressing senescent cells can improve health span, we discuss the function and possible exploitation of MAPKs in the elimination (senolysis) or suppression (senostasis) of senescent cells.

Therapy-Induced Senescence Drives Bone Loss

Chemotherapy is important for cancer treatment, however, toxicities limit its use. While great strides have been made to ameliorate the acute toxicities induced by chemotherapy, long-term comorbidities including bone loss remain a significant problem. Chemotherapy-driven estrogen loss is postulated to drive bone loss, but significant data suggests the existence of an estrogen-independent mechanism of bone loss. Using clinically relevant mouse models, we showed that senescence and its senescence-associated secretory phenotype (SASP) contribute to chemotherapy-induced bone loss that can be rescued by depleting senescent cells. Chemotherapy-induced SASP could be limited by targeting the p38MAPK-MK2 pathway, which resulted in preservation of bone integrity in chemotherapy-treated mice. These results transform our understanding of chemotherapy-induced bone loss by identifying senescent cells as major drivers of bone loss and the p38MAPK-MK2 axis as a putative therapeutic target that can preserve bone and improve a cancer survivor's quality of life. SIGNIFICANCE: Senescence drives chemotherapy-induced bone loss that is rescued by p38MAPK or MK2 inhibitors. These findings may lead to treatments for therapy-induced bone loss, significantly increasing quality of life for cancer survivors.

The Role of HSF1 and the Chaperone Network in the Tumor Microenvironment

Tumors are stressful environments. As tumors evolve from single mutated cancer cells into invasive malignancies they must overcome various constraints and barriers imposed by a hostile microenvironment. To achieve this, cancer cells recruit and rewire cells in their microenvironment to become pro-tumorigenic. We propose that chaperones are vital players in this process, and that activation of stress responses helps tumors adapt and evolve into aggressive malignancies, by enabling phenotypic plasticity in the tumor microenvironment (TME). In this chapter we will review evidence supporting non-cancer-cell-autonomous activity of chaperones in human patients and mouse models of cancer, discuss the mechanisms by which this non-cell-autonomous activity is mediated and provide an evolutionary perspective on the basis of this phenomenon.

A Comprehensive Review on MAPK: A Promising Therapeutic Target in Cancer

The mitogen-activated protein kinase (MAPK) pathway is an important bridge in the switch from extracellular signals to intracellular responses. Alterations of signaling cascades are found in various diseases, including cancer, as a result of genetic and epigenetic changes. Numerous studies focused on both the homeostatic and the pathologic conduct of MAPK signaling; however, there is still much to be deciphered in terms of regulation and action models in both preclinical and clinical research. MAPK has implications in the response to cancer therapy, particularly the activation of the compensatory pathways in response to experimental MAPK inhibition. The present paper discusses new insights into MAPK as a complex cell signaling pathway with roles in the sustenance of cellular normal conduit, response to cancer therapy, and activation of compensatory pathways. Unfortunately, most MAPK inhibitors trigger resistance due to the activation of compensatory feed-back loops in tumor cells and tumor microenvironment components. Therefore, novel combinatorial therapies have to be implemented for cancer management in order to restrict the possibility of alternative pathway activation, as a perspective for developing novel therapies based on integration in translational studies.

Unmasking senescence: context-dependent effects of SASP in cancer

Cellular senescence plays a critical role in tumorigenesis. Once thought of as a tissue culture artefact by some researchers, senescence is now a major field of study. Although there are common molecular mechanisms that enforce the growth arrest that characterizes the phenotype, the impact of senescence is varied and can, in some instances, have opposite effects on tumorigenesis. It has become clearer that the cell of origin and the tissue in question dictate the impact of senescence on tumorigenesis. In this Review, we unravel this complexity by focusing on how senescence impacts tumorigenesis when it arises within incipient tumour cells versus stromal cells, and how these roles can change in different stages of disease progression. In addition, we highlight the diversity of the senescent phenotype and its functional output beyond growth arrest: the senescence-associated secretory phenotype (SASP). Fortunately, a number of new genetic and pharmacologic tools have been developed that are now allowing the senescence phenotype to be parsed further.

PEGylated immunoliposome-loaded endoglin single-chain antibody enhances anti-tumor capacity of porcine α1,3GT gene

Tumor could not be completely removed due to the absence of immune storm against tumor. The porcine α1,3 galactosyltransferase (α1,3 GT) induce the hyperacute rejection by synthesizing Galα1-3Galβ1-(3)4GlcNAc-R (αGal) on the surface of graft endothelial cells (ECs) during xeno-transplantation. This study aimed to develop anti-endoglin single-chain Fv fragments (ENG-scFv) conjugated PEGylated immunoliposomes (iLPs) to induce immune storm against tumor. Immune fluorescence was performed to detect the binding of ENG-scFv to human ENG, the endosomal/lysosomal escape of ENG-scFv-iLPs/α1,3 GT, and αGal expression in hENG-HEK293 cells. In vitro MTT assay was performed to measure ENG-scFv-iLPs/α1,3 GT cytotoxicity. NOD/SCID mouse born A549 tumor model was used to evaluate the therapeutic potency of ENG-scFv-iLPs/α1,3 GT. ENG-scFv-iLPs enabled efficient targeting delivery of α1,3 GT plasmid to ENG + tumors neovascular endothelial cells (TnECs), promoted endosomal/lysosomal escape due to the pH-sensitive ability, then synthesized carbohydrate epitope αGal on the surface of these cells to achieve the purpose of destroying the tumor. The mechanism of uptake for nanoparticles was energy driven, the clathrin-mediated endocytosis was the main endocytic pathway of the ENG-mAb-iLPs/α1,3 GT and lipid-raft-mediated of the ENG-scFv-iLPs/α1,3 GT, and macropinocytosis was also involved in intracellular entry. The inhibition of tumor angiogenesis and proliferation by ENG-scFv-iLPs/α1,3 GT was closely related to down-regulation of VEGF. Our findings establish an alternative therapeutic paradigm for scFv-conjugated nanoparticles to induce tumor cell apoptosis and inhibit tumor growth early. Such iLPs nanocarrier could efficiently release α1,3 GT to their distinct sites of action, where the endoglin + tumor neovascular endothelial cells (ENG + TnECs) exist, in a site-specific manner. Therefore, we believe that these scFv-targeted core-shell immunocomplexes are an important potential α1,3 GT delivery system for various solid tumor-targeted therapy.

Stress responses in stromal cells and tumor homeostasis

In most (if not all) solid tumors, malignant cells are outnumbered by their non-malignant counterparts, including immune, endothelial and stromal cells. However, while the mechanisms whereby cancer cells adapt to microenvironmental perturbations have been studied in great detail, relatively little is known on stress responses in non-malignant compartments of the tumor microenvironment. Here, we discuss the mechanisms whereby cancer-associated fibroblasts and other cellular components of the tumor stroma react to stress in the context of an intimate crosstalk with malignant, endothelial and immune cells, and how such crosstalk influences disease progression and response to treatment.

Identification of stable senescence-associated reference genes

Cellular senescence is a state of permanent cell cycle arrest activated in response to damaging stimuli. Many hallmarks associated with senescent cells are measured by quantitative real-time PCR (qPCR). As the selection of stable reference genes for interpretation of qPCR data is often overlooked, we performed a systematic review to understand normalization strategies entailed in experiments involving senescent cells. We found that, in violation of the Minimum Information for publication of qPCR Experiments (MIQE) guidelines, most reports used only one reference gene to normalize qPCR data, and that stability of the reference genes was either not tested or not reported. To identify new and more stable reference genes in senescent fibroblasts, we analyzed the Shapiro-Wilk normality test and the coefficient of variation per gene using in public RNAseq datasets. We then compared the new reference gene candidates with commonly used ones by using both RNAseq and qPCR data. Finally, we defined the best reference genes to be used universally or in a strain-dependent manner. This study intends to raise awareness of the instability of classical reference genes in senescent cells and to serve as a first attempt to define guidelines for the selection of more reliable normalization methods.

Nuclear factor-erythroid 2-related factor 3 (NRF3) is low expressed in colorectal cancer and its down-regulation promotes colorectal cancer malignance through activating EGFR and p38/MAPK

Nuclear factor-erythroid 2-related factor 3 (NRF3), a nuclear transcription factor, has been implicated in various cellular processes including carcinogenesis. However, mechanisms underlying its regulation in carcinogenesis are unclear. Herein, we found that NRF3 is lowly expressed in colorectal cancer (CRC) tissues and cells, and NRF3 low-expressions in CRC tissue samples are associated with CRC carcinogenesis and poor patient outcomes. Nrf3-knockdown increased CRC cell growth, colony formation, and cell motility and invasion, and Nrf3-knockin dramatically decreased CRC cell growth and colony formation. Mechanistically, NRF3 increased CRC cell apoptosis and arrested cell G2/M stage. NRF3 was found to be reversely with epidermal growth factor receptor (EGFR) and p38. Strikingly, Nrf3-knockin dramatically decreased phosphorylated-EGFR at Tyrosine845 (pEGFR Tyr845) and phosphorylated-p38 at Threonine180/Tyrosine182 (p-p38 Thr180/Tyr182) expressions, and Nrf3-knockdown increased pEGFR Tyr845 and p-p38 Thr180/Tyr182. Moreover, NRF3 regulated EGFR and p38 down-stream molecules, protein kinase B (AKT), activating transcription factor (ATF) 2, and C/EBP homologous protein (CHOP) expressions. NRF3 loss-increased CRC growth through EGFR and p38 was confirmed in nude mice. Collectively, NRF3-loss in CRC cell increases EGFR and p38 phosphorylation activation, enhances cell proliferation and decreases cell apoptosis, and finally promotes CRC malignance.

Fibroblasts Mobilize Tumor Cell Glycogen to Promote Proliferation and Metastasis

Successful metastasis requires the co-evolution of stromal and cancer cells. We used stable isotope labeling of amino acids in cell culture coupled with quantitative, label-free phosphoproteomics to study the bidirectional signaling in ovarian cancer cells and human-derived, cancer-associated fibroblasts (CAFs) after co-culture. In cancer cells, the interaction with CAFs supported glycogenolysis under normoxic conditions and induced phosphorylation and activation of phosphoglucomutase 1, an enzyme involved in glycogen metabolism. Glycogen was funneled into glycolysis, leading to increased proliferation, invasion, and metastasis of cancer cells co-cultured with human CAFs. Glycogen mobilization in cancer cells was dependent on p38α MAPK activation in CAFs. In vivo, deletion of p38α in CAFs and glycogen phosphorylase inhibition in cancer cells reduced metastasis, suggesting that glycogen is an energy source used by cancer cells to facilitate metastatic tumor growth.

Tumor-on-a-chip platform to investigate progression and drug sensitivity in cell lines and patient-derived organoids

Most cancer treatment strategies target cell proliferation, angiogenesis, migration, and intravasation of tumor cells in an attempt to limit tumor growth and metastasis. An in vitro platform to assess tumor progression and drug sensitivity could provide avenues to enhance our understanding of tumor metastasis as well as precision medicine. We present a microfluidic platform that mimics biological mass transport near the arterial end of a capillary in the tumor microenvironment. A central feature is a quiescent perfused 3D microvascular network created prior to loading tumor cells or patient-derived tumor organoids in an adjacent compartment. The physiological delivery of nutrients and/or drugs to the tumor then occurs through the vascular network. We demonstrate the culture, growth, and treatment of tumor cell lines and patient-derived breast cancer organoids. The platform provides the opportunity to simultaneously and dynamically observe hallmark features of tumor progression including cell proliferation, angiogenesis, cell migration, and tumor cell intravasation. Additionally, primary breast tumor organoids are viable in the device for several weeks and induce robust sprouting angiogenesis. Finally, we demonstrate the feasibility of our platform for drug discovery and personalized medicine by analyzing the response to chemo- and anti-angiogenic therapy. Precision medicine-based cancer treatments can only be realized if individual tumors can be rapidly assessed for therapeutic sensitivity in a clinically relevant timeframe (⪅14 days). Our platform indicates that this goal can be achieved and provides compelling opportunities to advance precision medicine for cancer.

ZNF580 - a brake on Interleukin-6

Background

Zinc finger protein 580 (ZNF580) was reported to modulate angiogenesis, endothelial homeostasis and blood pressure control. ZNF580 regulated genes include VEGF-A and IL-8. However, it is unknown if ZNF580 could play a role during inflammation. The aim of this study was to find out if ZNF580 affects the expression of IL-6, if it occurs in monocytic cells and responds to inflammatory mediators.

Results

Overexpression of ZNF580 reduced LPS-induced promotor activity of IL-6. Consistently, overexpression of ZNF580 reduced by half the LPS-induced expression of IL-6. ZNF580 was strongly expressed in the nucleus of MonoMac6, a human monocytic cell line. LPS-stimulated IL-6 secretion increased when ZNF580 was suppressed with siRNA. After stimulation of MonoMac6 with LPS for 24 h, ZNF580 negatively correlated with the amount of secreted IL-6. In response to LPS, ZNF580 was increased within the first 8 h, followed by a marked decrease after 16 h. This decrease coincided with sustained IL-6 production.

Conclusion

This study demonstrated that ZNF580 inhibits LPS-induced expression of IL-6. ZNF580 was highly expressed in monocytic cells and therefore may contribute to the modulation of its IL-6 production, at least in response to LPS. This suggests cooperation between ZNF580 and NFκB, which could play a role during sepsis.

Inhibition of the Stromal p38MAPK/MK2 Pathway Limits Breast Cancer Metastases and Chemotherapy-Induced Bone Loss

The role of the stromal compartment in tumor progression is best illustrated in breast cancer bone metastases, where the stromal compartment supports tumor growth, albeit through poorly defined mechanisms. p38MAPKα is frequently expressed in tumor cells and surrounding stromal cells, and its expression levels correlate with poor prognosis. This observation led us to investigate whether inhibition of p38MAPKα could reduce breast cancer metastases in a clinically relevant model. Orally administered, small-molecule inhibitors of p38MAPKα or its downstream kinase MK2 each limited outgrowth of metastatic breast cancer cells in the bone and visceral organs. This effect was primarily mediated by inhibition of the p38MAPKα pathway within the stromal compartment. Beyond effectively limiting metastatic tumor growth, these inhibitors reduced tumor-associated and chemotherapy-induced bone loss, which is a devastating comorbidity that drastically affects quality of life for patients with cancer. These data underscore the vital role played by stromal-derived factors in tumor progression and identify the p38MAPK-MK2 pathway as a promising therapeutic target for metastatic disease and prevention of tumor-induced bone loss.Significance: Pharmacologically targeting the stromal p38MAPK-MK2 pathway limits metastatic breast cancer growth, preserves bone quality, and extends survival. Cancer Res; 78(19); 5618-30. ©2018 AACR.

Cellular Senescence: The Sought or the Unwanted?

Cellular senescence is a process that results in irreversible cell-cycle arrest, and is thought to be an autonomous tumor-suppressor mechanism. During senescence, cells develop distinctive metabolic and signaling features, together referred to as the senescence-associated secretory phenotype (SASP). The SASP is implicated in several aging-related pathologies, including various malignancies. Accumulating evidence argues that cellular senescence acts as a double-edged sword in human cancer, and new agents and innovative strategies to tackle senescent cells are in development pipelines to counter the adverse effects of cellular senescence in the clinic. We focus on recent discoveries in senescence research and SASP biology, and highlight the potential of SASP suppression and senescent cell clearance in advancing precision medicine.

IFITM3 promotes hepatocellular carcinoma invasion and metastasis by regulating MMP9 through p38/MAPK signaling

Interferon-induced transmembrane protein 3 (IFITM3) has been shown to be overexpressed in multiple cancers. However, the role of IFITM3 in metastasis of hepatocellular carcinoma (HCC) is still poorly understood. In this study, we showed that IFITM3 was frequently overexpressed in HCC tissues compared with adjacent nontumor tissues. Overexpression of IFITM3 was significantly correlated with tumor metastasis and poor prognosis in HCC. Knockdown of IFITM3 dramatically decreased MMP9 expression and inhibited the invasion and metastasis of HCC in vitro and in vivo. Moreover, the upregulation of MMP9 rescued the decreased migration and invasion induced by the knockdown of IFITM3, whereas the knockdown of MMP9 decreased IFITM3-enhanced HCC migration and invasion. Mechanistically, we found that IFITM3 regulates MMP9 expression through the p38/MAPK pathway. Taken together, we identified a novel IFITM3-p38/MAPK-MMP9 regulatory circuitry, the dysfunction of which drives invasive and metastatic character in HCC.

The senescence-associated secretory phenotype is potentiated by feedforward regulatory mechanisms involving Zscan4 and TAK1

The senescence-associated secretory phenotype (SASP) can be provoked by side effects of therapeutic agents, fueling advanced complications including cancer resistance. However, the intracellular signal network supporting initiation and development of the SASP driven by treatment-induced damage remains unclear. Here we report that the transcription factor Zscan4 is elevated for expression by an ATM-TRAF6-TAK1 axis during the acute DNA damage response and enables a long term SASP in human stromal cells. Further, TAK1 activates p38 and PI3K/Akt/mTOR to support the persistent SASP signaling. As TAK1 is implicated in dual feedforward mechanisms to orchestrate the SASP development, pharmacologically targeting TAK1 deprives cancer cells of resistance acquired from treatment-damaged stromal cells in vitro and substantially promotes tumour regression in vivo. Together, our study reveals a novel network that links functionally critical molecules associated with the SASP development in therapeutic settings, thus opening new avenues to improve clinical outcomes and advance precision medicine.

In cancer the side effects of therapeutic agents can provoke senescence-associated secretory phenotype (SASP), which can drive cancer resistance. During the DNA damage response, transcription factor Zscan4 expression is elevated by an ATM-TRAF6-TAK1 axis leading to long term SASP in human stromal cells.

Role of p38 MAPK in disease relapse and therapeutic resistance by maintenance of cancer stem cells in head and neck squamous cell carcinoma

AIM

This study aimed to investigate the role of p38 MAPK in maintenance of cancer stem cell (CSC) phenotype, therapy resistance, and DNA damage repair and response in head and neck squamous cell carcinoma (HNSCC).

METHODS

In this study, 104 HNSCC patients were included. Western blot, immunohistochemistry, and qPCR analysis were performed to investigate the expression level of p-p38 and CSC markers in cut margin and tumor area of HNSCC patients. The expression level of p-p38 and CSC markers was also evaluated in HNSCC cells with or without p38 inhibitor. Chemoresistance, wound healing capacity, and multicellular tumor spheroids (MCTS) formation capacity were evaluated in HNSCC-derived cell lines with or without p38 inhibitor. In addition, DNA damage response and repair capacities were also evaluated in HNSCC cells after p38 inhibition using alkaline comet assay and γ-H₂ AX immunostaining.

RESULT

We observed that recurrence could be associated with upregulated status of p-p38 and p38α gene in cut margin area of HNSCC patients as compared to tumor region. p38-inhibited cells showed significantly reduced expression of CSC markers, chemosensitivity toward cisplatin, reduced migration potential, and sphere-forming ability along with increased apoptotic population after treatment with increasing concentration of cisplatin. p38-inhibited cells also exhibited significantly increased comet olive tail moment and accumulation of γ-H₂ AX, demonstrating increased DNA damage.

CONCLUSION

This study demonstrated that p38 MAPK activation may play a role in therapeutic resistance and disease relapse in HNSCC by maintenance of CSCs phenotype.

Lung carcinogenesis and fibrosis taken together: just coincidence?

PURPOSE OF REVIEW

The pathogenesis of lung cancer and pulmonary fibrotic disorders partially overlaps. This review focuses on the common features of the two disease categories, aimed at advancing our translational understanding of their pathobiology and at fostering the development of new therapies.

RECENT FINDINGS

Both malignant and collagen-producing lung cells display enhanced cellular proliferation, increased resistance to apoptosis, a propensity for invading and distorting the lung parenchyma, as well as stemness potential. These characteristics are reinforced by the tissue microenvironment and inflammation seems to play an important adjuvant role in both types of disorders.

SUMMARY

Unraveling the thread of the common and distinct characteristics of lung fibrosis and cancer might contribute to a more comprehensive approach of the pathobiology of both diseases and to a pathfinder for novel and personalized therapeutic strategies.

c-Myb and C/EBPβ regulate OPN and other senescence-associated secretory phenotype factors

Tumorigenesis results from the convergence of cell autonomous mutations and corresponding stromal changes that promote tumor cell growth. Senescent cells, which secrete a plethora of pro-tumorigenic factors termed the senescence-associated secretory phenotype (SASP), play an important role in tumor formation. Investigation into SASP regulation revealed that many but not all SASP factors are subject to NF-kB and p38MAPK regulation. However, many pro-tumorigenic SASP factors, including osteopontin (OPN), are not responsive to these canonical pathways leaving the regulation of these factors an open question. We report that the transcription factor c-Myb regulates OPN, IL-6, and IL-8 in addition to 57 other SASP factors. The regulation of OPN is direct as c-Myb binds to the OPN promoter in response to senescence. Further, OPN is also regulated by the known SASP regulator C/EBPβ. In response to senescence, the full-length activating C/EBPβ isoform LAP2 increases binding to the OPN, IL-6, and IL-8 promoters. The importance of both c-Myb and C/EBPβ is underscored by our finding that the depletion of either factor reduces the ability of senescent fibroblasts to promote the growth of preneoplastic epithelial cells.

"Social Life" of Senescent Cells: What Is SASP and Why Study It?

Cellular senescence was first described as a failure of normal human cells to divide indefinitely in culture. Until recently, the emphasis in the study of cell senescence has been focused on the accompanying intracellular processes. The focus of the attention has been on the irreversible growth arrest and two important physiological functions that rely on it: suppression of carcinogenesis due to the proliferation loss of damaged cells, and the acceleration of organism aging due to the deterioration of the tissue repair mechanism with age. However, the advances of the past years have revealed that senescent cells can impact the surrounding tissue microenvironment, and, thus, that the main consequences of senescence are not solely mediated by intracellular alterations. Recent studies have provided evidence that a pool of molecules secreted by senescent cells, including cytokines, chemokines, proteases and growth factors, termed the senescence-associated secretory phenotype (SASP), via autocrine/paracrine pathways can affect neighboring cells. Today it is clear that SASP functionally links cell senescence to various biological processes, such as tissue regeneration and remodeling, embryonic development, inflammation, and tumorigenesis. The present article aims to describe the "social" life of senescent cells: basically, SASP constitution, molecular mechanisms of its regulation, and its functional role.

Phase 1 and pharmacokinetic study of LY3007113, a p38 MAPK inhibitor, in patients with advanced cancer

Background The signaling protein p38 mitogen-activated protein kinase (MAPK) regulates the tumor cell microenvironment, modulating cell survival, migration, and invasion. This phase 1 study evaluated the safety of p38 MAPK inhibitor LY3007113 in patients with advanced cancer to establish a recommended phase 2 dose. Methods In part A (dose escalation), LY3007113 was administered orally every 12 h (Q12H) at doses ranging from 20 mg to 200 mg daily on a 28-day cycle until the maximum tolerated dose (MTD) was reached. In part B (dose confirmation), patients received MTD. Safety, pharmacokinetics, pharmacodynamics, and tumor response data were evaluated. Results MTD was 30 mg Q12H. The most frequent treatment-related adverse events (>10%) were tremor, rash, stomatitis, increased blood creatine phosphokinase, and fatigue. Grade ≥ 3 treatment-related adverse events included upper gastrointestinal haemorrhage and increased hepatic enzyme, both occurring at 40 mg Q12H and considered dose-limiting toxicities. LY3007113 exhibited an approximately dose-proportional increase in exposure and time-independent pharmacokinetics after repeated dosing. Maximal inhibition (80%) of primary biomarker MAPK-activated protein kinase 2 in peripheral blood mononuclear cells was not reached, and sustained minimal inhibition (60%) was not maintained for 6 h after dosing to achieve a biologically effective dose (BED). The best overall response in part B was stable disease in 3 of 27 patients. Conclusions The recommended phase 2 dosage of LY3007113 was 30 mg Q12H. Three patients continued treatment after the first radiographic assessment, and the BED was not achieved. Further clinical development of this compound is not planned as toxicity precluded achieving a biologically effective dose.

Spatial and Temporal Control of Senescence

Cellular senescence is an autonomous tumor suppressor mechanism leading to stable cell cycle arrest. Senescent cells are highly secretory, driving a range of different functions through the senescence-associated secretory phenotype (SASP). Recent findings have suggested that the composition of the SASP is dynamically and spatially regulated and that the changing composition of the SASP can determine the beneficial and detrimental aspects of the senescence program, tipping the balance to either an immunosuppressive/profibrotic environment or proinflammatory/fibrolytic state. Here, we discuss the current understanding of the temporal and spatial regulation of the SASP and the novel finding of NOTCH signaling as a regulator of SASP composition.

Cancer-associated fibroblasts support vascular growth through mechanical force

The role of cancer-associated fibroblasts (CAFs) as regulators of tumor progression, specifically vascular growth, has only recently been described. CAFs are thought to be more mechanically active but how this trait may alter the tumor microenvironment is poorly understood. We hypothesized that enhanced mechanical activity of CAFs, as regulated by the Rho/ROCK pathway, contributes to increased blood vessel growth. Using a 3D in vitro tissue model of vasculogenesis, we observed increased vascularization in the presence of breast cancer CAFs compared to normal breast fibroblasts. Further studies indicated this phenomenon was not simply a result of enhanced soluble signaling factors, including vascular endothelial growth factor (VEGF), and that CAFs generated significantly larger deformations in 3D gels compared to normal fibroblasts. Inhibition of the mechanotransductive pathways abrogated the ability of CAFs to deform the matrix and suppressed vascularization. Finally, utilizing magnetic microbeads to mechanically stimulate mechanically-inhibited CAFs showed partial rescue of vascularization. Our studies demonstrate enhanced mechanical activity of CAFs may play a crucial and previously unappreciated role in the formation of tumor-associated vasculature which could possibly offer potential novel targets in future anti-cancer therapies.

Tumor p38MAPK signaling enhances breast carcinoma vascularization and growth by promoting expression and deposition of pro-tumorigenic factors

The breast carcinoma microenvironment strikingly influences cancer progression and response to therapy. Various cell types in the carcinoma microenvironment show significant activity of p38 mitogen-activated protein kinase (MAPK), although the role of p38MAPK in breast cancer progression is still poorly understood. The present study examined the contribution of tumor p38MAPK to breast carcinoma microenvironment and metastatic capacity. Inactivation of p38MAPK signaling in metastatic breast carcinoma cells was achieved by forced expression of the kinase-inactive mutant of p38/MAPK14 (a dominant-negative p38, dn-p38). Disruption of tumor p38MAPK signaling reduced growth and metastases of breast carcinoma xenografts. Importantly, dn-p38 markedly decreased tumor blood-vessel density and lumen sizes. Mechanistic studies revealed that p38 controls expression of pro-angiogenic extracellular factors such as matrix protein Fibronectin and cytokines VEGFA, IL8, and HBEGF. Tumor-associated fibroblasts enhanced tumor growth and vasculature as well as increased expression of the pro-angiogenic factors. These effects were blunted by dn-p38. Metadata analysis showed elevated expression of p38 target genes in breast cancers and this was an unfavorable marker of disease recurrence and poor-outcome. Thus, our study demonstrates that tumor p38MAPK signaling promotes breast carcinoma growth, invasive and metastatic capacities. Importantly, p38 enhances carcinoma vascularization by facilitating expression and deposition of pro-angiogenic factors. These results argue that p38MAPK is a valuable target for anticancer therapy affecting tumor vasculature. Anti-p38 drugs may provide new therapeutic strategies against breast cancer, including metastatic disease.

Unmasking Transcriptional Heterogeneity in Senescent Cells

Cellular senescence is a state of irreversibly arrested proliferation, often induced by genotoxic stress [1]. Senescent cells participate in a variety of physiological and pathological conditions, including tumor suppression [2], embryonic development [3, 4], tissue repair [5-8], and organismal aging [9]. The senescence program is variably characterized by several non-exclusive markers, including constitutive DNA damage response (DDR) signaling, senescence-associated β-galactosidase (SA-βgal) activity, increased expression of the cyclin-dependent kinase (CDK) inhibitors p16INK4A (CDKN2A) and p21CIP1 (CDKN1A), increased secretion of many bio-active factors (the senescence-associated secretory phenotype, or SASP), and reduced expression of the nuclear lamina protein LaminB1 (LMNB1) [1]. Many senescence-associated markers result from altered transcription, but the senescent phenotype is variable, and methods for clearly identifying senescent cells are lacking [10]. Here, we characterize the heterogeneity of the senescence program using numerous whole-transcriptome datasets generated by us or publicly available. We identify transcriptome signatures associated with specific senescence-inducing stresses or senescent cell types and identify and validate genes that are commonly differentially regulated. We also show that the senescent phenotype is dynamic, changing at varying intervals after senescence induction. Identifying novel transcriptome signatures to detect any type of senescent cell or to discriminate among diverse senescence programs is an attractive strategy for determining the diverse biological roles of senescent cells and developing specific drug targets.

Isolation of Fibroblast-Activation Protein-Specific Cancer-Associated Fibroblasts

The current study is to develop a gentle and efficient method for purification of fibroblast-activation protein positive (FAP⁺) cancer-associated fibroblasts (CAFs) from tumor tissues. Fresh tissues were isolated from BALB/c-Nude mice bearing human liver cancer cell line (HepG2), fully minced and separated into three parts, and digested with trypsin digestion and then treated with collagenase type IV once, twice, or thrice, respectively. Finally, the cells were purified by using FAP magnetic beads. The isolated CAFs were grown in culture medium and detected for the surface expression of fibroblast-activation protein (FAP). The number of adherent cells which were obtained by digestion process with twice collagenase type IV digestion was (5.99 ± 0.18) × 10⁴, much more than that with the only once collagenase type IV digestion (2.58 ± 0.41) × 10⁴ (P < 0.0001) and similar to thrice collagenase type IV digestion. The percentage of FAP⁺ CAFs with twice collagenase type IV digestion (38.5%) was higher than that with the only once collagenase type IV digestion (20.0%) and little higher than thrice collagenase type IV digestion (37.5%). The FAP expression of CAFs was quite different from normal fibroblasts (NFs). The fibroblasts isolated by the innovation are with high purity and being in wonderful condition and display the features of CAFs.

Cancer secretome and inflammation: The bright and the dark sides of NF-κB

Tumour promoting inflammation is widely recognized as a hallmark of cancer. The source of this chronic inflammation in cancer has been ascribed to the progressive activation over time of immune cells, mostly of the innate arm of the immune system. However, recent evidence has shown that chronic inflammation may also derive, at least in part, from senescent cells. Hence, due to the prominent role of inflammation in cancer, the cancer secretome definition includes all the secretory factors ensuing from the crosstalk between the cancer cell and the tumour microenvironment. The mechanistic basis underlying the paracrine signalling between the cancer cell and the surrounding tumour microenvironment in malignancy have been widely investigated by using in vivo models of cancers, thus identifying the NF-κB transcription factor as the molecular hub linking inflammation and cancer. In this review, we highlight the roles of NF-κB in regulating the inflammation-derived secretome emanating from immune and senescent cells, with a special focus on the bright and the dark sides of their pro-inflammatory signalling on tumorigenesis.

p38 MAPK inhibits nonsense-mediated RNA decay in response to persistent DNA damage in noncycling cells

Persistent DNA damage induces profound alterations in gene expression that, in turn, influence tissue homeostasis, tumorigenesis, and cancer treatment outcome. However, the underlying mechanism for gene expression reprogramming induced by persistent DNA damage remains poorly understood. Here, using a highly effective bioluminescence-based reporter system and other tools, we report that persistent DNA damage inhibits nonsense-mediated RNA decay (NMD), an RNA surveillance and gene-regulatory pathway, in noncycling cells. NMD suppression by persistent DNA damage required the activity of the p38α MAPK. Activating transcription factor 3 (ATF3), an NMD target and a key stress-inducible transcription factor, was stabilized in a p38α- and NMD-dependent manner following persistent DNA damage. Our results reveal a novel p38α-dependent pathway that regulates NMD activity in response to persistent DNA damage, which, in turn, controls ATF3 expression in affected cells.

p38MAPK builds a hyaluronan cancer niche to drive lung tumorigenesis

Brichkina et al. show that lung cancer growth depends on short-distance cues produced by the cancer niche and identify fibroblast-specific hyaluronan synthesis at the center of p38-driven tumorigenesis. This in turn regulates early stromal fibroblast activation, the conversion to carcinoma-associated fibroblasts (CAFs), and cancer cell proliferation.

Expansion of neoplastic lesions generates the initial signal that instigates the creation of a tumor niche. Nontransformed cell types within the microenvironment continuously coevolve with tumor cells to promote tumorigenesis. Here, we identify p38MAPK as a key component of human lung cancer, and specifically stromal interactomes, which provides an early, protumorigenic signal in the tissue microenvironment. We found that lung cancer growth depends on short-distance cues produced by the cancer niche in a p38-dependent manner. We identified fibroblast-specific hyaluronan synthesis at the center of p38-driven tumorigenesis, which regulates early stromal fibroblast activation, the conversion to carcinoma-associated fibroblasts (CAFs), and cancer cell proliferation. Systemic down-regulation of p38MAPK signaling in a knock-in model with substitution of activating Tyr182 to phenylalanine or conditional ablation of p38 in fibroblasts has a significant tumor-suppressive effect on K-ras lung tumorigenesis. Furthermore, both Kras-driven mouse lung tumors and orthotopically grown primary human lung cancers show a significant sensitivity to both a chemical p38 inhibitor and an over-the-counter inhibitor of hyaluronan synthesis. We propose that p38MAPK–hyaluronan-dependent reprogramming of the tumor microenvironment plays a critical role in driving lung tumorigenesis, while blocking this process could have far-reaching therapeutic implications.

The p38 pathway, a major pleiotropic cascade that transduces stress and metastatic signals in endothelial cells

By gating the traffic of molecules and cells across the vessel wall, endothelial cells play a central role in regulating cardiovascular functions and systemic homeostasis and in modulating pathophysiological processes such as inflammation and immunity. Accordingly, the loss of endothelial cell integrity is associated with pathological disorders that include atherosclerosis and cancer. The p38 mitogen-activated protein kinase (MAPK) cascades are major signaling pathways that regulate several functions of endothelial cells in response to exogenous and endogenous stimuli including growth factors, stress and cytokines. The p38 MAPK family contains four isoforms p38α, p38β, p38γ and p38δ that are encoded by four different genes. They are all widely expressed although to different levels in almost all human tissues. p38α/MAPK14, that is ubiquitously expressed is the prototype member of the family and is referred here as p38. It regulates the production of inflammatory mediators, and controls cell proliferation, differentiation, migration and survival. Its activation in endothelial cells leads to actin remodeling, angiogenesis, DNA damage response and thereby has major impact on cardiovascular homeostasis, and on cancer progression. In this manuscript, we review the biology of p38 in regulating endothelial functions especially in response to oxidative stress and during the metastatic process.

Senescent peritoneal mesothelium creates a niche for ovarian cancer metastases

Although both incidence and aggressiveness of ovarian malignancy rise with age, the exact reason for this tendency, in particular the contribution of senescent cells, remains elusive. In this project we found that the patient's age determines the frequency of intraperitoneal metastases of ovarian cancer. Moreover, we documented that senescent human peritoneal mesothelial cells (HPMCs) stimulate proliferation, migration and invasion of ovarian cancer cells in vitro, and that this effect is related to both the activity of soluble agents released to the environment by these cells and direct cell-cell contact. The panel of mediators of the pro-cancerous activity of senescent HPMCs appeared to be cancer cell line-specific. The growth of tumors in a mouse peritoneal cavity was intensified when the cancer cells were co-injected together with senescent HPMCs. This effect was reversible when the senescence of HPMCs was slowed down by the neutralization of p38 MAPK. The analysis of lesions excised from the peritoneum of patients with ovarian cancer showed the abundance of senescent HPMCs in close proximity to the cancerous tissue. Collectively, our findings indicate that senescent HPMCs which accumulate in the peritoneum in vivo may create a metastatic niche facilitating intraperitoneal expansion of ovarian malignancy.