Regulation of interleukin-8 expression in melanoma-stimulated neutrophil inflammatory response

Susceptibility of Melanoma Cells to Targeted Therapy Correlates with Protection by Blood Neutrophils

Elevated levels of peripheral blood and tumor tissue neutrophils are associated with poorer clinical response and therapy resistance in melanoma. The underlying mechanism and the role of neutrophils in targeted therapy is still not fully understood. Serum samples of patients with advanced melanoma were collected and neutrophil-associated serum markers were measured and correlated with response to targeted therapy. Blood neutrophils from healthy donors and patients with advanced melanoma were isolated, and their phenotypes, as well as their in vitro functions, were compared. In vitro functional tests were conducted through nonadherent cocultures with melanoma cells. Protection of melanoma cell lines by neutrophils was assessed under MAPK inhibition. Blood neutrophils from advanced melanoma patients exhibited lower CD16 expression compared to healthy donors. In vitro, both healthy-donor- and patient-derived neutrophils prevented melanoma cell apoptosis upon dual MAPK inhibition. The effect depended on cell-cell contact and melanoma cell susceptibility to treatment. Interference with protease activity of neutrophils prevented melanoma cell protection during treatment in cocultures. The negative correlation between neutrophils and melanoma outcomes seems to be linked to a protumoral function of neutrophils. In vitro, neutrophils exert a direct protective effect on melanoma cells during dual MAPK inhibition. This study further hints at a crucial role of neutrophil-related protease activity in protection.

Mechanobiology in oncology: basic concepts and clinical prospects

The interplay between genetic transformations, biochemical communications, and physical interactions is crucial in cancer progression. Metastasis, a leading cause of cancer-related deaths, involves a series of steps, including invasion, intravasation, circulation survival, and extravasation. Mechanical alterations, such as changes in stiffness and morphology, play a significant role in all stages of cancer initiation and dissemination. Accordingly, a better understanding of cancer mechanobiology can help in the development of novel therapeutic strategies. Targeting the physical properties of tumours and their microenvironment presents opportunities for intervention. Advancements in imaging techniques and lab-on-a-chip systems enable personalized investigations of tumor biomechanics and drug screening. Investigation of the interplay between genetic, biochemical, and mechanical factors, which is of crucial importance in cancer progression, offers insights for personalized medicine and innovative treatment strategies.

Granulocyte Apheresis: Can It Be Associated with Anti PD-1 Therapy for Melanoma?

In the field of advanced melanoma, there is an urgent need to investigate novel approaches targeting specific components of the cancer–immunity cycle beyond immune checkpoint inhibitors. The authors reviewed the basic understanding of the role of neutrophils in cancer biology, and the latest clinical evidence supporting the correlation between cancer-associated neutrophils and the prognosis and response to the immunotherapy of advanced melanoma. Finally, they propose that granulocyte and monocyte apheresis, an emerging non-pharmacological treatment in current dermatology, could become an investigative treatment targeting melanoma-associated neutrophils which could be potentially used in combination with the usual immune checkpoint inhibitors.

Melanoma Stem Cells Educate Neutrophils to Support Cancer Progression

Simple Summary

In melanoma patients, poor prognosis often correlates with high presence of cancer-associated neutrophils, indicating that tumors can recruit these immune cells to specifically sustain their own development and progression. However, the role of cancer stem cells (CSCs) in this dialogue has not been elucidated yet. Our results revealed that melanoma SCs can reshape the immune microenvironment by triggering a pro-tumor N2 phenotype in neutrophils, which in turn are able to confer stemness properties to melanoma cells.

Abstract

Background: It is now well-established that cancer stem cells (CSCs) can support melanoma progression by reshaping the tumor immune microenvironment. However, the molecular mechanisms underlying the crosstalk between melanoma SCs and cancer-associated neutrophils have not been elucidated yet. Methods: The aim of the present study was to unravel the role of melanoma SCs in neutrophil polarization. HL60 neutrophil-like (dHL60) cells were treated with conditioned medium from A375 melanoma SCs (CSC-CM), and their phenotype was investigated. Results: We demonstrated that CSC-CM could specifically activate immune cells by increasing CD66b and CD11b expression. In particular, we revealed that A375 CSCs could release various soluble factors, namely TGF-β, IL-6, and IL-8, able to promote the recruitment of neutrophils and their switch toward an N2 phenotype characterized by the activation of ERK, STAT3, and P38 pathways and the overexpression of CXCR2 and NF-kB. Moreover, after exposure to CSC-CM, dHL60 cells exhibited enhanced ROS production and NET release, without undergoing cell death; increased secretion of MMP-9 and pro-inflammatory cytokines was also observed. Finally, CSC-CM-activated neutrophils endowed A375 cells with stemness traits, stimulating both sphere formation and ABCG2 expression. Conclusion: Collectively, our results suggest that melanoma SCs can prime neutrophils to support cancer progression.

ALDH1A1 overexpression in melanoma cells promotes tumor angiogenesis by activating the IL‑8/Notch signaling cascade

ALDH1A1 is a cytosolic enzyme upregulated in tumor cells, involved in detoxifying cells from reactive aldehydes and in acquiring resistance to chemotherapeutic drugs. Its expression correlates with poor clinical outcomes in a number of cancers, including melanoma. The present study hypothesized that the increased ALDH1A1 expression and activity upregulated the release of proangiogenic factors from melanoma cells, which regulate angiogenic features in endothelial cells (ECs) through a rearrangement of the Notch pathway. In vivo, when subcutaneously implanted in immunodeficient mice, ALDH1A1 overexpressing melanoma cells displayed a higher microvessel density. In a 3D multicellular system, obtained co‑culturing melanoma cancer cells with stromal cells, including ECs, melanoma ALDH1A1 overexpression induced the recruitment of ECs into the core of the tumorspheres. By using a genes array, overexpression of ALDH1A1 in tumor cells also promoted modulation of Notch cascade gene expression in ECs, suggesting an interaction between tumor cells and ECs mediated by enrichment of angiogenic factors in the tumor microenvironment. To confirm this hypothesis, inactivation of ALDH1A1 by the pharmacological inhibitor CM037 significantly affected the release of angiogenic factors, including IL‑8, from melanoma cells. High levels of ALDH1A1, through the retinoic acid pathway, regulated the activation of NF‑kB‑p65 and IL‑8. Further, in a 2D co‑culture system, the addition of an IL‑8 neutralizing antibody to ECs co‑cultured with melanoma cells forced to express ALDH1A1 dampened endothelial angiogenic features, both at the molecular (in terms of gene and protein expression of mediators of the Notch pathway) and at the functional level (proliferation, scratch assay, tube formation and permeability). In conclusion, these findings demonstrated the existence of a link between melanoma ALDH1A1 expression and EC Notch signaling modification that results in a pro‑angiogenic phenotype. Based on the crucial role of ALDH1A1 in melanoma control of the tumor microenvironment, the enzyme seems a promising target for the development of novel drugs able to interrupt the cross‑talk between cancer (stem) cells and endothelial cells.

Thrombin-Activated Platelets Protect Vascular Endothelium against Tumor Cell Extravasation by Targeting Endothelial VCAM-1

When activated by thrombin, the platelets release their granular store of factors. These thrombin-activated platelets (TAPLT) have been shown to be capable of ameliorating pro-inflammatory processes. In this study, we tested if TAPLT could also protect the endothelium against tumor-related pro-inflammatory changes that promote angiogenesis and metastasis. Using endothelial cell (EC) models in vitro, we demonstrated that TAPLT protected EC against tumor conditioned medium (TCM)-induced increases of reactive oxygen species (ROS) production, EC permeability and angiogenesis, and inhibited transendothelial migration that was critical for cancer cell extravasation and metastasis. In vivo observations of TAPLT-mediated inhibition of angiogenesis and pulmonary colonization in a BALB/c nude mouse model were consistent with the in vitro findings. Neutralization of vascular cell adhesion molecule-1 (VCAM-1) binding significantly inhibited the ability of TAPLT to interact with EC and abrogated the TAPLT-mediated protection of EC against tumor angiogenesis and metastasis. Taken together, these findings suggest that VCAM-1-mediated linkage to EC is required for TAPLT to confer protection of EC against tumor-induced permeation and angiogenesis, thereby resisting tumor extravasation and metastasis.

Polymorphonuclear Neutrophils and Tumors: Friend or Foe?

Tumor microenvironment (TME) is a dynamic network that apart from tumor cells includes also cells of the immune system, e.g., neutrophils, which are recruited from blood circulation. In TME, neutrophils are strongly implicated in the direct and indirect interactions with tumor cells or other immune cells, and they play roles in both preventing and/or facilitating tumor progression and metastasis. The dual role of neutrophils is determined by their high plasticity and heterogeneity. Analogous to the macrophages, neutrophils can express antitumoral (N1) and protumoral (N2) phenotypes which differ substantially in morphology and function. N1 phenotype characterizes with a high cytotoxic and proinflammatory activities, while N2 phenotype with immunosuppressive and prometastatic properties. The antitumoral effect of neutrophils includes for example the production of reactive oxygen species or proapoptotic molecules. The protumoral action of neutrophils relies on releasing of proangiogenic and prometastatic mediators, immunosuppressive factors, as well as on direct helping tumor cells in extravasation process. This chapter summarizes the heterogeneity of neutrophils in TME, as well as their dual role on tumor cells.

Interleukin-8 in Melanoma Pathogenesis, Prognosis and Therapy-An Integrated View into Other Neoplasms and Chemokine Networks

Cutaneous melanoma accounts for only about 7% of skin cancers but is causing almost 90% of deaths. Melanoma cells have a distinct repertoire of mutations from other cancers, a high plasticity and degree of mimicry toward vascular phenotype, stemness markers, versatility in evading and suppress host immune control. They exert a significant influence on immune, endothelial and various stromal cells which form tumor microenvironment. The metastatic stage, the leading cause of mortality in this neoplasm, is the outcome of a complex, still poorly understood, cross-talk between tumor and other cell phenotypes. There is accumulating evidence that Interleukin-8 (IL-8) is emblematic for advanced melanomas. This work aimed to present an updated status of IL-8 in melanoma tumor cellular complexity, through a comprehensive analysis including data from other chemokines and neoplasms. The multiple processes and mechanisms surveyed here demonstrate that IL-8 operates following orchestrated programs within signaling webs in melanoma, stromal and vascular cells. Importantly, the yet unknown molecularity regulating IL-8 impact on cells of the immune system could be exploited to overturn tumor fate. The molecular and cellular targets of IL-8 should be brought into the attention of even more intense scientific exploration and valorization in the therapeutical management of melanoma.

Measurement of 45 cytokine, chemokine and growth factors in established cell culture supernatants and autologous serum from advanced melanoma patients

Melanoma is one of the most aggressive forms of human cancer and its incidence has significantly increased worldwide over the last decades. This neoplasia has been characterized by the release of a wide variety of soluble factors, which could stimulate tumor cell proliferation and survival in an autocrine and paracrine manner. Consequently, we sought to evaluate the pattern of soluble factors produced by pre-metastatic and metastatic melanoma established cultures, and to determine whether these factors can be detected in the autologous serum of malignant melanoma patients. Our results showed that both melanoma cultures had a common profile of 27 soluble factors mainly characterized by the high expression of VEGF-A, IL-6, MCP-1, IL-8, and SDF-1. In addition, when we compared supernatants, we observed significant differences in VEGF-A, BDNF, FGF-2, and NGF-β concentrations. As we found in melanoma cultures, serum samples also had their specific production pattern composed by 21 soluble factors. Surprisingly, PDGF-BB and EGF were only found in serum, whereas IL-2, IL-4, IL-8, IL31, FGF2, and GRO-α were only expressed in the supernatant. Significant differences in PDGF-BB, MIP-1β, HGF, PIGF-1, BDNF, EGF, Eotaxin, and IP-10 were also found after comparing autologous serum with healthy controls. According to this, no correlation was found between culture supernatants and autologous serum samples, which suggests that some factors may act locally, and others systemically. Nonetheless, after validation of our results in an independent cohort of patients, we concluded that PDGF-BB, VEGF-A, and IP-10 serum levels could be used to monitor different melanoma stages.

The Influence of Tumor Microenvironment on Immune Escape of Melanoma

The low efficiency of currently-used anti-cancer therapies poses a serious challenge, especially in the case of malignant melanoma, a cancer characterized by elevated invasiveness and relatively high mortality rate. The role of the tumor microenvironment in the progression of melanoma and its acquisition of resistance to treatment seems to be the main focus of recent studies. One of the factors that, in normal conditions, aids the organism in its fight against the cancer and, following the malignant transformation, adapts to facilitate the development of the tumor is the immune system. A variety of cell types, i.e., T and B lymphocytes, macrophages, and dendritic and natural killer cells, as well as neutrophils, support the growth and invasiveness of melanoma cells, utilizing a plethora of mechanisms, including secretion of pro-inflammatory molecules, induction of inhibitory receptors expression, or depletion of essential nutrients. This review provides a comprehensive summary of the processes regulated by tumor-associated cells that promote the immune escape of melanoma cells. The described mechanisms offer potential new targets for anti-cancer treatment and should be further studied to improve currently-employed therapies.

Antithrombin attenuates the progression of hepatocellular carcinoma by regulating neutrophil/interleukin-8 signaling

AIM

Inflammation plays an important role in hepatocellular carcinoma (HCC) progression. Here, we examined whether antithrombin (AT) plays a role in attenuating HCC progression, via its anti-inflammatory effects.

METHODS

HCCs were developed in AT-insufficient (AT^+/- ) mice and wild-type (AT^+/+ ) mice treated with diethyl nitrosamine and carbon tetrachloride. AT was administered to AT^+/- mice. The development of HCC was compared between the three groups. In vitro study, migration assay was performed. The association of the prognosis of patients with HCC and plasma AT values was clinically examined.

RESULTS

AT suppressed the release of interleukin (IL)-8 from lipopolysaccharide (LPS)-stimulated human neutrophils in vitro. Huh-7 cells that were co-cultured with neutrophils and stimulated with LPS showed significantly enhanced migration; however, Huh-7 cells co-cultured with LPS/AT-stimulated neutrophils showed significantly decreased migration. Moreover, the addition of anti-IL-8 antibodies to LPS-stimulated Huh-7 cells co-cultured with neutrophils also suppressed migration. AT^+/- mice (AT plasma activity: 64%) promoted liver cancer, as compared with wild-type mice (AT plasma activity: 135%); AT administration attenuated liver cancer in AT^+/- mice. Patients with HCC with a preoperative AT level of ≥70% showed better outcomes after liver resection, as compared with those with an AT level of <70%. IL-8 expression and neutrophil infiltration in HCC tissues were negatively correlated with the AT level.

CONCLUSIONS

AT attenuates HCC progression by regulating neutrophil/IL-8 signaling.

Elevated Neutrophil-to-Lymphocyte Ratio Is Associated With Poor Outcomes for Melanoma Patients Treated With PD-1 Inhibitor or Chemotherapy in a Chinese Population

Background: Previous studies have suggested that an elevated pre-treatment neutrophil-to-lymphocyte ratio (NLR) is associated with worse outcomes in patients with a variety of cancers. The purpose of this retrospective analysis is to investigate the prognostic value of the NLR in a Chinese melanoma population.

Methods: Melanoma patients were divided into two groups based on pre-treatment NLR values (≥3 vs. <3). Cox proportional hazard regression analysis and the Kaplan-Meier method were employed to study the prognostic role of the NLR for overall survival (OS) and progression-free survival (PFS).

Results: A total of 159 melanoma patients were included in this study, including 40 patients treated with PD-1 inhibitor and 119 patients treated with chemotherapy. In the PD-1 inhibitor group, the median OS was 18.0 months in the low NLR subgroup and 5.6 months in the high NLR subgroup; the median PFS was 7.0 and 2.2 months, respectively. In chemotherapy group, the median OS was 23.0 months in the low NLR group and 8.0 months in the high NLR group, and the median PFS was 9.0 and 4.0 months, respectively. Multivariate analysis showed that the NLR was significantly associated with OS and PFS in melanoma patients treated with either PD-1 inhibitor immunotherapy or chemotherapy.

Conclusion: In the Chinese population, an elevated NLR was closely related to worse survival in patients with melanoma treated with either PD-1 inhibitor monotherapy or chemotherapy.

Neutrophils: Accomplices in metastasis

Metastasis is a critical cause of treatment failure and death in patients with advanced malignancies. Tumor cells can leave the primary site and enter the bloodstream; these circulating tumor cells then colonize target organs by overcoming blood shear stress, evading immune surveillance, and silencing the offensive capabilities of immune cells, eventually forming metastatic foci. From leaving the primary focus to the completion of distant metastasis, malignant tumor cells are supported and/or antagonized by certain immune cells. In particular, it has been found that myeloid granulocytes play an important role in this process. This review therefore aims to comprehensively describe the significance of neutrophils in solid tumor metastasis in terms of their supporting role in initiating the invasion and migration of tumor cells and assisting the colonization of circulating tumor cells in distant target organs, with the hope of providing insight into and ideas for anti-tumor metastasis treatment of tumor patients.

Pre-clinical modeling of cutaneous melanoma

Metastatic melanoma is challenging to manage. Although targeted- and immune therapies have extended survival, most patients experience therapy resistance. The adaptability of melanoma cells in nutrient- and therapeutically-challenged environments distinguishes melanoma as an ideal model for investigating therapy resistance. In this review, we discuss the current available repertoire of melanoma models including two- and three-dimensional tissue cultures, organoids, genetically engineered mice and patient-derived xenograft. In particular, we highlight how each system recapitulates different features of melanoma adaptability and can be used to better understand melanoma development, progression and therapy resistance.

Despite the new targeted and immunotherapies for metastatic melanoma, several patients show therapeutic plateau. Here, the authors review the current pre-clinical models of cutaneous melanoma and discuss their strengths and limitations that may help with overcoming therapeutic plateau.

Two-Faced Roles of Tumor-Associated Neutrophils in Cancer Development and Progression

Neutrophils are the most abundant circulating leukocytes in humans. Neutrophil infiltration into tumor tissues has long been observed but its roles have been ignored due to the presumed short life cycle and metabolic incompetence of neutrophils. Recent advances in neutrophil biology research have revealed that neutrophils have a longer life cycle with a potential to express various bioactive molecules. Clinical studies have simultaneously unraveled an increase in the neutrophil–lymphocyte ratio (NLR), a ratio of absolute neutrophil to absolute lymphocyte numbers in cancer patient peripheral blood and an association of higher NLR with more advanced or aggressive disease. As a consequence, tumor-associated neutrophils (TANs) have emerged as important players in tumor microenvironment. The elucidation of the roles of TANs, however, has been hampered by their multitude of plasticity in terms of phenotypes and functionality. Difficulties are further enhanced by the presence of a related cell population—polymorphonuclear leukocyte (PMN)-myeloid-derived suppressor cells (MDSCs)—and various dissimilar aspects of neutrophil biology between humans and mice. Here, we discuss TAN biology in various tumorigenesis processes, and particularly focus on the context-dependent functional heterogeneity of TANs.

ICAM1 expression is induced by proinflammatory cytokines and associated with TLS formation in aggressive breast cancer subtypes

Intratumoral formation of tertiary lymphoid structures (TLS) within the tumor microenvironment is considered to be a consequence of antigen challenge during anti-tumor responses. Intracellular adhesion molecule 1 (ICAM1) has been implicated in a variety of immune and inflammatory responses, in addition to associate with triple negative breast cancer (TNBC). In this study, we detected TLS in the aggressive tumor phenotypes TNBC, HER2+ and luminal B, whereas the TLS negative group contained solely tumors of the luminal A subtype. We show that ICAM1 is exclusively expressed in TNBC and HER2 enriched subtypes known to be associated with inflammation and the formation of TLS. Furthermore, cell from normal mammary epithelium and breast cancer cell lines expressed ICAM1 upon stimulation with the proinflammatory cytokines TNFα, IL1β and IFNγ. ICAM1 overexpression was induced in MCF7, MDA-MB-468 and SK-BR-3 cells regardless of hormone receptor status. Taken together, our findings show that ICAM1 is expressed in aggressive subtypes of breast cancer and its expression is inducible by well-known proinflammatory cytokines. ICAM1 may be an attractive molecular target for TNBC, but further investigations elucidating the role of ICAM1 in targeted therapies have to take into consideration selective subtypes of breast cancer.

The Role of Lipoproteins in Mycoplasma-Mediated Immunomodulation

Mycoplasma infections, such as walking pneumonia or pelvic inflammatory diseases, are a major threat to public health. Despite their relatively small physical and genomic size, mycoplasmas are known to elicit strong host immune responses, generally inflammatory, while also being able to evade the immune system. The mycoplasma membrane is composed of approximately two-thirds protein and one-third lipid and contains several lipoproteins that are known to regulate host immune responses. Herein, the immunomodulatory effects of mycoplasma lipoproteins are reviewed. A better understanding of the immunomodulatory effects, both activating and evasive, of Mycoplasma surface lipoproteins will contribute to understanding mechanisms potentially relevant to mycoplasma disease vaccine development and treatment.

Prognostic values of hematological biomarkers in nasopharyngeal carcinoma patients treated with intensity-modulated radiotherapy

Purpose

In this study, we evaluated the prognostic values of hematological biomarkers in primary nasopharyngeal carcinoma (NPC) patients receiving definitive intensity-modulated radiotherapy (IMRT).

Methods

There were 427 NPC patients enrolled between January 2010 and March 2013 at Fudan University Shanghai Cancer Center. Pre-treatment absolute neutrophil count (ANC), platelet count (APC), lymphocyte count (ALC), neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) were collected as prognostic biomarkers. The Kaplan–Meier method and log-rank test were utilized to calculate progression-free survival (PFS) and overall survival (OS). The Cox proportional hazard models were applied to assess variables.

Results

ANC, APC and ALC were declined, while NLR and PLR were elevated significantly after therapy (P < 0.001 each). On multivariate analysis, pre-treatment NLR ≥ 2.32 was associated with shortened OS (P = 0.048) and PFS (P = 0.008), whereas PLR ≥ 123.0 was related with inferior OS (P = 0.032), yet it was not correlated with PFS (P = 0.161).

Conclusions

High pre-treatment NLR and PLR indicated poor survival in NPC patients treated with IMRT-based therapy. As easily accessible and economically feasible biomarkers, NLR and PLR can be applied into clinical practice, in combination with current TNM staging, to design a more personalized treatment in these patients.

From Cancer Immunoediting to New Strategies in Cancer Immunotherapy: The Roles of Immune Cells and Mechanics in Oncology

For the last three decades, the concept of immunoediting has evolved to characterize our increasing understanding of the interactions between cells from the immune system and cancer development. Elucidating the role of immune cells in the progression of cancer has been very challenging due to their dual role; the immune system can either suppress tumor formation by killing cancer cells, or it can also promote tumor growth. Revealing how immune cells are hampered by the tumor microenvironment and how they aid tumor progression has signaled strategies to reverse these effects and control cancer cell growth; this has been the advent of immunotherapy design. More recently, the role of physical forces in the process of immunoediting has been highlighted by multiple studies focusing on understanding how force changes in the stiffness of the extracellular matrix and fluid flow shear stress contribute to tumor development. Using models in vitro that incorporate biomechanical components, it has been shown that these physical aspects are not only important during the formation and growth of primary tumors, but in the metastatic process as well. In this way, we have also gained insight into the interactions occurring within the vascular system, which are highly affected by the dynamics of physical collisions between cells and by shear forces. Here, we review the concept of cancer immunoediting with an emphasis on biomechanics and conclude with a summary on current immunotherapies and potential new strategies.

VE-Cadherin Disassembly and Cell Contractility in the Endothelium are Necessary for Barrier Disruption Induced by Tumor Cells

During metastasis, breakdown of the endothelial barrier is critical for tumor cell extravasation through blood vessel walls and is mediated by a combination of tumor secreted soluble factors and receptor-ligand interactions. However, a complete mechanism governing tumor cell transendothelial migration remains unclear. Here, we investigate the roles of tumor-associated signals in regulating endothelial cell contractility and adherens junction disassembly leading to endothelial barrier breakdown. We show that Src mediates VE-cadherin disassembly in response to metastatic melanoma cells. Through the use of pharmacological inhibitors of cytoskeletal contractility we find that endothelial cell contractility is responsive to interactions with metastatic cancer cells and that reducing endothelial cell contractility abrogates migration of melanoma cells across endothelial monolayers. Furthermore, we find that a combination of tumor secreted soluble factors and receptor-ligand interactions mediate activation of Src within endothelial cells that is necessary for phosphorylation of VE-cadherin and for breakdown of the endothelial barrier. Together, these results provide insight into how tumor cell signals act in concert to modulate cytoskeletal contractility and adherens junctions disassembly during extravasation and may aid in identification of therapeutic targets to block metastasis.

Immune Cell-Mediated Biodegradable Theranostic Nanoparticles for Melanoma Targeting and Drug Delivery

Although tremendous efforts have been made on targeted drug delivery systems, current therapy outcomes still suffer from low circulating time and limited targeting efficiency. The integration of cell-mediated drug delivery and theranostic nanomedicine can potentially improve cancer management in both therapeutic and diagnostic applications. By taking advantage of innate immune cell's ability to target tumor cells, the authors develop a novel drug delivery system by using macrophages as both nanoparticle (NP) carriers and navigators to achieve cancer-specific drug delivery. Theranostic NPs are fabricated from a unique polymer, biodegradable photoluminescent poly (lactic acid) (BPLP-PLA), which possesses strong fluorescence, biodegradability, and cytocompatibility. In order to minimize the toxicity of cancer drugs to immune cells and other healthy cells, an anti-BRAF V600E mutant melanoma specific drug (PLX4032) is loaded into BPLP-PLA nanoparticles. Muramyl tripeptide is also conjugated onto the nanoparticles to improve the nanoparticle loading efficiency. The resulting nanoparticles are internalized within macrophages, which are tracked via the intrinsic fluorescence of BPLP-PLA. Macrophages carrying nanoparticles deliver drugs to melanoma cells via cell-cell binding. Pharmacological studies also indicate that the PLX4032 loaded nanoparticles effectively kill melanoma cells. The "self-powered" immune cell-mediated drug delivery system demonstrates a potentially significant advancement in targeted theranostic cancer nanotechnologies.

Are neutrophil/lymphocyte ratio and platelet/lymphocyte ratio reliable parameters as prognostic indicators in malignant mesothelioma?

BACKGROUND

Malignant mesothelioma (MM) is an aggressive asbestos-related pleural tumor. The incidence is increasing with intensive use of asbestos in developing countries. We need an easily accessible, inexpensive, and reliable method for determining the low survival time prognosis of this tumor. The aim of our study was to investigate the viability of neutrophil/lymphocyte ratio (NLR) and platelet/lymphocyte ratio (PLR) as prognostic indicators in MM.

PATIENTS AND METHODS

Thirty-six patients with MM, whose histopathologic diagnosis and follow-up were performed by our clinic and whose complete archive data were accessible, were included in this retrospective study. The patients' histopathologic disease types and stages, complete blood count parameters at diagnosis, and survival were recorded.

RESULTS

Eighteen of the patients with MM were male and the remaining 18 of them were female; the average follow-up period was 24.83±3.61 months. The PLR levels of the patients were statistically significant (P<0.05). The NLR and PLR area under the receiver operating characteristic curve values were 0.559 and 0.749, respectively (P=0.631 and P=0.044, respectively).

CONCLUSION

PLR was a significant prognostic indicator of MM at diagnosis on complete blood count parameters; however, NLR was not a significant prognostic indicator. A large number of prospective studies are needed to prove the reliability of the parameters.

Neutrophil-derived chemokines on the road to immunity

During recent years, it has become clear that polymorphonuclear neutrophils are remarkably versatile cells, whose functions go far beyond phagocytosis and killing. In fact, besides being involved in primary defense against infections-mainly through phagocytosis, generation of toxic molecules, release of toxic enzymes and formation of extracellular traps-neutrophils have been shown to play a role in finely regulating the development and the evolution of inflammatory and immune responses. These latter neutrophil-mediated functions occur by a variety of mechanisms, including the production of newly manufactured cytokines. Herein, we provide a general overview of the chemotactic cytokines/chemokines that neutrophils can potentially produce, either under inflammatory/immune reactions or during their activation in more prolonged processes, such as in tumors. We highlight recent observations generated from studying human or rodent neutrophils in vitro and in vivo models. We also discuss the biological significance of neutrophil-derived chemokines in the context of infectious, neoplastic and immune-mediated diseases. The picture that is emerging is that, given their capacity to produce and release chemokines, neutrophils exert essential functions in recruiting, activating and modulating the activities of different leukocyte populations.

Inhibition of BET bromodomains as a therapeutic strategy for cancer drug discovery

As a conserved protein interaction module that recognizes and binds to acetylated lysine, bromodomain (BRD) contains a deep, largely hydrophobic acetyl lysine binding site. Proteins that share the feature of containing two BRDs and an extra-terminal domain belong to BET family, including BRD2, BRD3, BRD4 and BRDT. BET family proteins perform transcription regulatory function under normal conditions, while in cancer, they regulate transcription of several oncogenes, such as c-Myc and Bcl-2. Thus, targeting BET proteins may be a promising strategy, and intense interest of BET proteins has fueled the development of structure-based bromodomain inhibitors in cancer. In this review, we focus on summarizing several small-molecule BET inhibitors and their relevant anti-tumor mechanisms, which would provide a clue for exploiting new targeted BET inhibitors in the future cancer therapy.

Mutant B-Raf(V600E) Promotes Melanoma Paracellular Transmigration by Inducing Thrombin-mediated Endothelial Junction Breakdown

Tumor invasiveness depends on the ability of tumor cells to breach endothelial barriers. In this study, we investigated the mechanism by which the adhesion of melanoma cells to endothelium regulates adherens junction integrity and modulates tumor transendothelial migration (TEM) by initiating thrombin generation. We found that the B-Raf(V600E) mutation in metastatic melanoma cells up-regulated tissue factor (TF) expression on cell membranes and promoted thrombin production. Co-culture of endothelial monolayers with metastatic melanoma cells mediated the opening of inter-endothelial spaces near melanoma cell contact sites in the presence of platelet-free plasma (PFP). By using small interfering RNA (siRNA), we demonstrated that B-Raf(V600E) and TF silencing attenuated the focal disassembly of adherens junction induced by tumor contact. Vascular endothelial-cadherin (VE-cadherin) disassembly was dependent on phosphorylation of p120-catenin on Ser-879 and VE-cadherin on Tyr-658, Tyr-685, and Tyr-731, which can be prevented by treatment with the thrombin inhibitor, hirudin, or by silencing the thrombin receptor, protease-activated receptor-1, in endothelial cells. We also provided strong evidence that tumor-derived thrombin enhanced melanoma TEM by inducing ubiquitination-coupled VE-cadherin internalization, focal adhesion formation, and actin assembly in endothelium. Confocal microscopic analysis of tumor TEM revealed that junctions transiently opened and resealed as tumor cells accomplished TEM. In addition, in the presence of PFP, tumor cells preferentially transmigrated via paracellular routes. PFP supported melanoma transmigration under shear conditions via a B-Raf(V600E)-thrombin-dependent mechanism. We concluded that the activation of thrombin generation by cancer cells in plasma is an important process regulating melanoma extravasation by disrupting endothelial junction integrity.

Nuclear stiffening inhibits migration of invasive melanoma cells

During metastasis, melanoma cells must be sufficiently deformable to squeeze through extracellular barriers with small pore sizes. We visualize and quantify deformability of single cells using micropipette aspiration and examine the migration potential of a population of melanoma cells using a flow migration apparatus. We artificially stiffen the nucleus with recombinant overexpression of Δ50 lamin A, which is found in patients with Hutchison Gilford progeria syndrome and in aged individuals. Melanoma cells, both WM35 and Lu1205, both show reduced nuclear deformability and reduced cell invasion with the expression of Δ50 lamin A. These studies suggest that cellular aging including expression of Δ50 lamin A and nuclear stiffening may reduce the potential for metastatic cancer migration. Thus, the pathway of cancer metastasis may be kept in check by mechanical factors in addition to known chemical pathway regulation.

CD44 variant, but not standard CD44 isoforms, mediate disassembly of endothelial VE-cadherin junction on metastatic melanoma cells

Loss of endothelial adherens junctions is involved in tumor metastasis. Here, we demonstrate that, in the metastatic Lu1205 melanoma cells, expression of the CD44 variant CD44v8-v10 induced junction disassembly and vascular endothelial (VE)-cadherin phosphorylation at Y658 and Y731. Short interfering RNA (siRNA)-mediated CD44 knockdown or sialic acid cleavage reversed these effects. Moreover, microspheres coated with recombinant CD44v8-v10 promoted endothelial junction disruption. Overexpression of CD44v8-v10 but not of standard CD44 (CD44s) promoted gap formation in the non-metastatic WM35 melanoma cells, whereas CD44 knockdown or neuraminidase treatment dramatically diminished melanoma transendothelial migration. Endothelial cells transfected with the phosphomimetic VE-cadherin mutant Y658E supported transmigration of CD44-silenced Lu1205 cells. Our findings imply that CD44 variant isoform (CD44v) but not CD44s regulates endothelial junction loss, promoting melanoma extravasation.

Thrombospondin-1 is part of a Slug-independent motility and metastatic program in cutaneous melanoma, in association with VEGFR-1 and FGF-2

Differently from most transformed cells, cutaneous melanoma expresses the pleiotropic factor thrombospondin-1 (TSP-1). Herein, we show that TSP-1 (RNA and protein), undetectable in four cultures of melanocytes and a RGP melanoma, was variously present in 13 cell lines from advanced melanomas or metastases. Moreover, microarray analysis of 55 human lesions showed higher TSP-1 expression in primary melanomas and metastases than in common and dysplastic nevi. In a functional enrichment analysis, the expression of TSP-1 correlated with motility-related genes. Accordingly, TSP-1 production was associated with melanoma cell motility in vitro and lung colonization potential in vivo. VEGF/VEGFR-1 and FGF-2, involved in melanoma progression, regulated TSP-1 production. These factors were coexpressed with TSP-1 and correlated negatively with Slug (SNAI2), a cell migration master gene implicated in melanoma metastasis. We conclude that TSP-1 cooperates with FGF-2 and VEGF/VEGFR-1 in determining melanoma invasion and metastasis, as part of a Slug-independent motility program.

Melanoma upregulates ICAM-1 expression on endothelial cells through engagement of tumor CD44 with endothelial E-selectin and activation of a PKCα-p38-SP-1 pathway

Cancer metastasis involves multistep adhesive interactions between tumor cells (TCs) and endothelial cells (ECs), but the molecular mechanisms of intercellular communication in the tumor microenvironment remain elusive. Using static and flow coculture systems in conjunction with flow cytometry, we discovered that certain receptors on the ECs are upregulated on melanoma cell adhesion. Direct contact but not separate coculture between human umbilical endothelial cells (HUVECs) and a human melanoma cell line (Lu1205) increased intercellular adhesion molecule 1 (ICAM-1) and E-selectin expression on HUVECs by 3- and 1.5-fold, respectively, compared with HUVECs alone. The nonmetastatic cell line WM35 failed to promote ICAM-1 expression changes in HUVECs on contact. Enzyme-linked immunosorbent assay (ELISA) revealed that EC-TC contact has a synergistic effect on the expression of the cytokines interleukin (IL)-8, IL-6, and growth-related oncogene α (Gro-α). By using E-selectin cross-linking and beads coated with CD44 immunopurified from Lu1205 cells, we showed that CD44/selectin ligation was responsible for the ICAM-1 up-regulation on HUVECs. Protein kinase Cα (PKC-α) activation was found to be the downstream target of the CD44/selectin-initiated signaling, as ICAM-1 elevation was inhibited by siRNA targeting PKCα or a dominant negative form of PKCα (PKCα DN). Western blot analysis and electrophoretic mobility shift assays (EMSAs) showed that TC-EC contact mediated p38 phosphorylation and binding of the transcription factor SP-1 to its regulation site. In conclusion, CD44/selectin binding signals ICAM-1 up-regulation on the EC surface through a PKCα-p38-SP-1 pathway, which further enhances melanoma cell adhesion to ECs during metastasis.

The IL-6-STAT3 axis mediates a reciprocal crosstalk between cancer-derived mesenchymal stem cells and neutrophils to synergistically prompt gastric cancer progression

Emerging evidence indicate that mesenchymal stem cells (MSCs) affect tumor progression by reshaping the tumor microenvironment. Neutrophils are essential component of the tumor microenvironment and are critically involved in cancer progression. Whether the phenotype and function of neutrophils is influenced by MSCs is not well understood. Herein, we investigated the interaction between neutrophils and gastric cancer-derived MSCs (GC-MSCs) and explored the biological role of this interaction. We found that GC-MSCs induced the chemotaxis of neutrophils and protected them from spontaneous apoptosis. Neutrophils were activated by the conditioned medium from GC-MSCs with increased expression of IL-8, TNFα, CCL2, and oncostatin M (OSM). GC-MSCs-primed neutrophils augmented the migration of gastric cancer cells in a cell contact-dependent manner but had minimal effect on gastric cancer cell proliferation. In addition, GC-MSCs-primed neutrophils prompted endothelial cells to form tube-like structure in vitro. We demonstrated that GC-MSCs stimulated the activation of STAT3 and ERK1/2 pathways in neutrophils, which was essential for the functions of activated neutrophils. We further revealed that GC-MSCs-derived IL-6 was responsible for the protection and activation of neutrophils. In turn, GC-MSCs-primed neutrophils induced the differentiation of normal MSCs into cancer-associated fibroblasts (CAFs). Collectively, our results suggest that GC-MSCs regulate the chemotaxis, survival, activation, and function of neutrophils in gastric cancer via an IL-6-STAT3-ERK1/2 signaling cascade. The reciprocal interaction between GC-MSCs and neutrophils presents a novel mechanism for the role of MSCs in remodeling cancer niche and provides a potential target for gastric cancer therapy.

Characterization of LY2228820 dimesylate, a potent and selective inhibitor of p38 MAPK with antitumor activity

p38α mitogen-activated protein kinase (MAPK) is activated in cancer cells in response to environmental factors, oncogenic stress, radiation, and chemotherapy. p38α MAPK phosphorylates a number of substrates, including MAPKAP-K2 (MK2), and regulates the production of cytokines in the tumor microenvironment, such as TNF-α, interleukin-1β (IL-1β), IL-6, and CXCL8 (IL-8). p38α MAPK is highly expressed in human cancers and may play a role in tumor growth, invasion, metastasis, and drug resistance. LY2228820 dimesylate (hereafter LY2228820), a trisubstituted imidazole derivative, is a potent and selective, ATP-competitive inhibitor of the α- and β-isoforms of p38 MAPK in vitro (IC(50) = 5.3 and 3.2 nmol/L, respectively). In cell-based assays, LY2228820 potently and selectively inhibited phosphorylation of MK2 (Thr334) in anisomycin-stimulated HeLa cells (at 9.8 nmol/L by Western blot analysis) and anisomycin-induced mouse RAW264.7 macrophages (IC(50) = 35.3 nmol/L) with no changes in phosphorylation of p38α MAPK, JNK, ERK1/2, c-Jun, ATF2, or c-Myc ≤ 10 μmol/L. LY2228820 also reduced TNF-α secretion by lipopolysaccharide/IFN-γ-stimulated macrophages (IC(50) = 6.3 nmol/L). In mice transplanted with B16-F10 melanoma, tumor phospho-MK2 (p-MK2) was inhibited by LY2228820 in a dose-dependent manner [threshold effective dose (TED)(70) = 11.2 mg/kg]. Significant target inhibition (>40% reduction in p-MK2) was maintained for 4 to 8 hours following a single 10 mg/kg oral dose. LY2228820 produced significant tumor growth delay in multiple in vivo cancer models (melanoma, non-small cell lung cancer, ovarian, glioma, myeloma, breast). In summary, LY2228820 is a p38 MAPK inhibitor, which has been optimized for potency, selectivity, drug-like properties (such as oral bioavailability), and efficacy in animal models of human cancer.

CD82/KAI expression prevents IL-8-mediated endothelial gap formation in late-stage melanomas

Melanoma cells facilitate endothelial gap formation, the first step during tumor transendothelial migration, which is mediated by both adhesion and endogenously produced chemokines (in particular, interleukin-8 (IL-8)). Tetraspanins are localized to the cell surface in cancer and participate in various functions including invasion of tissues mediated by secretion of cytokines and matrix metalloproteinases. However, little is known about the role of CD82 tetraspanins in malignant melanomas during cancer cell invasion. In this study, we investigated the functional importance of CD82 expression in melanoma-mediated gap formation by using cDNAs to induce CD82 expression in highly invasive melanoma cell lines. Results showed that CD82 expression inhibited melanoma cell-induced gap formation, melanoma cell extravasation in vitro and subsequent lung metastasis development in vivo. Mechanistic studies showed that inducible expression of CD82 in highly metastatic melanoma cells significantly increased p21 expression upon binding of Duffy antigen receptor group (DARC), inducing tumor cell senescence and interrupting IL-8-mediated vascular endothelial (VE)-cadherin disassembly. Taken together, these studies provide a rationale for using drug therapies that restore CD82 expression and inhibit IL-8 production to inhibit late-stage melanoma cell extravasation and subsequent metastasis development.

Tumor associated macrophages and neutrophils in cancer

The tumor microenvironment is a complex framework, in which myeloid cells play important roles in sculpting cancer development from tumor initiation to metastasis. Immune cells are key participants of the tumor microenvironment where they can promote or inhibit cancer formation and development. Plasticity is a widely accepted hallmark of myeloid cells and in particular of the monocyte-macrophage lineage. It includes the ability to display a wide spectrum of activation states in response to distinct signals and classical M1 or alternative M2 macrophages represent a paradigm of this feature. Neutrophils have long been viewed as terminally differentiated effector cells, playing a major role during the acute phase of inflammation and resistance against microbes. Recent evidence questioned this limited point of view, indicating that neutrophils can interact with distinct cell populations and produce a wide number of cytokines and effector molecules. Therefore, macrophages and neutrophils are both integrated in the regulation of the innate and adaptive immune responses in various inflammatory situations, including cancer.

Monocytes mediate metastatic breast tumor cell adhesion to endothelium under flow

Endothelial adhesion is necessary for the hematogenous dissemination of tumor cells. However, the metastatic breast tumor cell MDA-MB-231 does not bind to the endothelium under physiological flow conditions, suggesting alternate mechanisms of adhesion. Since monocytes are highly represented in the tumor microenvironment, and also bind to endothelium during inflammation, we hypothesized that the monocytes assist in the arrest of MDA-MB-231 on the endothelium. Using in vitro models of the dynamic shear environment of the vasculature, we show that TNF-α-activated THP1/primary human monocytes and MDA-MB-231 cells form stable aggregates, and that the monocytes in these aggregates mediate the adhesion of otherwise nonadherent MDA-MB-231 cells to inflamed endothelium under flow (55±2.4 vs. 1.7±0.82 at a shear stress of 0.5 dyn/cm(2), P<0.01). We also show that the hydrodynamic forces determine the size and orientation of aggregates adhered to the endothelium, and strongly favor the attachment of small aggregates with tumor cells downstream of flow (74-86% doublets at 0.5-2 dyn/cm(2), P<0.01). The 5-fold up-regulation of ICAM-1 on TNF-α-activated MDA-MB-231 cells through the Nf-κB pathway was found to be critical in MDA-MB-231-monocyte aggregation and endothelial adhesion. Our results demonstrate that, under inflammatory conditions, monocytes may serve to disseminate tumor cells through circulation, and the tumor-monocyte-endothelial axis may represent a new therapeutic target to reduce cancer metastasis.

The kinship of neutrophils and granulocytic myeloid-derived suppressor cells in cancer: cousins, siblings or twins?

Neutrophils in the tumor host may promote tumor progression by enhancing angiogenesis, invasion and metastasis. Granulocytic myeloid-derived suppressor cells (MDSC) share many features with neutrophils. Classically, MDSC are viewed as and defined as immunosuppressive cells. In this article we summarize and critically review evidence for a role of MDSC in promoting angiogenesis, invasion and metastasis of solid tumors. We also attempt to provide a critical evaluation of the relationship between neutrophils and G-MDSC in the tumor host with a particular focus on human cancer.

Modulation of neutrophil granulocytes in the tumor microenvironment: mechanisms and consequences for tumor progression

Accumulating evidence indicates a critical role of myeloid cells in the pathophysiology of human cancers. In contrast to the well-characterized tumor-associated macrophages (TAMs), the significance of granulocytes in cancer has only recently begun to emerge. Increased numbers of neutrophil granulocytes have been observed both in the peripheral blood and in the tumor tissues of patients with different types of cancer. Importantly, these studies linked neutrophils to poor clinical outcome in cancer patients which suggests that these cells might have important tumor-promoting activities. Indeed, a number of functional in vitro and in vivo studies demonstrated that tumors stimulated neutrophils to promote angiogenesis and immunosuppression, as well as migration, invasion and metastasis of the tumor cells. Therefore, it became necessary to understand the mechanisms modulating the changes in the biology and functions of neutrophils in the context of the tumor microenvironment. In this review we will discuss several functions of neutrophils that might contribute to tumor progression. Furthermore, we will address in detail the cellular and molecular mechanisms that control modulation of neutrophils in the tumor microenvironment, such as recruitment to the tumor site (chemotaxis), prolonged survival and enhanced release of protumoral mediators.

Dysfunctional activation of neurotensin/IL-8 pathway in hepatocellular carcinoma is associated with increased inflammatory response in microenvironment, more epithelial mesenchymal transition in cancer and worse prognosis in patients

Aim

To investigate the role of neurotensin (NTS) in hepatocellular carcinoma (HCC) sub- grouping and the clinical and pathological significance of activation of NTS/IL-8 pathway in HCC.

Methods

The genome-wide gene expression profiling were conducted in 10 pairs of cancer tissues and corresponding normal adjacent tissues samples using Affymetrix GeneChip® Human Genome U133 Plus 2.0 microarray to screen differentially expressing genes and enrich dysfunctional activated pathways among different HCC subgroups. The levels of NTS protein and multiple inflammation and epithelial mesenchymal transition (EMT) related proteins, including IL-8, VEGF, MMP9, CD68, E-Cadherin, β-Catenin and Vimentin were examined in 64 cases of paraffin-embedded HCC samples using immunohistochemistry (IHC) staining method. The clinical outcome and overall survival (OS) were compared.

Results

A subgroup of HCC characterized by up-regulated NTS expression was accompanied by up-regulated inflammatory responses and EMT. The direct interaction between NTS and IL-8 was identified by pathway enrichment analysis. Significantly increased IL-8 protein was confirmed in 90.91% of NTS⁺ HCC samples and significantly positively correlated to the levels of NTS protein in cancer tissues (P = 0.036), which implied activation of NTS/IL-8 pathway in HCC. The levels of VEGF and MMP9 correlated with co-expression of NTS and IL-8. Increased infiltration of CD68⁺ macrophages and more cancer cells displaying EMT features were found in NTS⁺IL-8⁺ samples. The co-expression of NTS and IL-8 in cancer significantly correlated with the clinical outcomes, as the mortality rate of NTS⁺IL-8⁺ HCC patients is 2.5-fold higher than the others after the surgery (P = 0.022). Accordingly, the OS of NTS⁺IL-8⁺ HCC patients significantly decreased who are under a higher hazard of death at an expected hazard ratio (HR) of 3.457.

Conclusion

Dysfunctional activation of the NTS/IL-8 pathway was detected in HCC which is associated with increased inflammatory response in microenvironment, enhanced EMT in cancer, and worse prognosis in HCC patients.

On the cytokines produced by human neutrophils in tumors

Although traditionally viewed as short-lived innate immunity cells, only playing a crucial role in host defense toward infections, neutrophils have recently become subject of a new wave of research in diverse areas including in tumors. Indeed, increasing experimental evidence indicate that neutrophils may directly or indirectly influence the tumor fate through the release of a wide array of molecules able to exert either pro-tumor or anti-tumor functions depending on the microenvironment milieu, including cytokines. This review therefore attempts to uncover the role that neutrophils play during the different steps of tumor development (from promotion to progression), as well as in anti-tumor responses, via cytokine production.

On the dual roles and polarized phenotypes of neutrophils in tumor development and progression

Inconsistencies plague our understanding of the role of neutrophils in cancer and the literature provides evidence for a duality in neutrophil activity on the outcome of cancer. Here, the different effects of neutrophils during the multiple subprocesses of cancer development and progression are overviewed, in order to gain insight into the features of both antitumoral and protumoral tumor-associated neutrophils (TAN). Neutrophils can counteract the progression of malignancies through tumor cytotoxicity, tumor rejection and enhancement of antitumoral immune memory. These cells have recently been phenotypically denominated N1 neutrophils. Recent studies indicate that cytokines, such as TGF-β and IFN-β, are involved in directing neutrophil polarization by the tumor microenvironment. With the opposite polarity, N2 neutrophils may be detrimental for the host and beneficial for tumor growth, invasion and metastasis, e.g. through proteolysis of extracellullar matrix components, promotion of angiogenesis and mediation of immunosuppression.

Suppression of the proinflammatory response of metastatic melanoma cells increases TRAIL-induced apoptosis

Melanoma is the most lethal form of human skin cancer. However, only limited chemotherapy is currently available for the metastatic stage of the disease. Since chemotherapy, radiation and sodium arsenite treatment operate mainly through induction of the intrinsic mitochondrial pathway, a strongly decreased mitochondrial function in metastatic melanoma cells, could be responsible for low efficacy of the conventional therapy of melanoma. Another feature of metastatic melanoma cells is their proinflammatory phenotype, linked to endogenous expression of the inflammatory cytokines, such as TNFα IL6 and IL8, their receptors, and constitutive NF-κB- and STAT3-dependent gene expression, including cyclooxygenase-2 (PTGS2/COX2). In the present study, we treated melanoma cells with immunological (monoclonal antibody against TNFα or IL6), pharmacological (small molecular inhibitors of IKKβ-NF-κB and JAK2-STAT3) or genetic (specific RNAi for COX-2) agents that suppressed the inflammatory response in combination with induction of apoptosis via TRAIL. As a result of these combined treatments, exogenous TRAIL via interactions with TRAIL-R2/R1 strongly increased levels of apoptosis in resistant melanoma cells. The present study provides new understanding of the regulation of TRAIL-mediated apoptosis in melanoma and will serve as the foundation for the potential development of a novel approach for a therapy of resistant melanomas.

Inflammation and tumor microenvironment in lymph node metastasis

In nearly all human cancers, the presence of lymph node (LN) metastasis increases clinical staging and portends worse prognosis (compared to patients without LN metastasis). Herein, principally reviewing experimental and clinical data related to malignant melanoma, we discuss diverse factors that are mechanistically involved in LN metastasis. We highlight recent data that link tumor microenvironment, including inflammation (at the cellular and cytokine levels) and tumor-induced lymphangiogenesis, with nodal metastasis. Many of the newly identified genes that appear to influence LN metastasis facilitate general motility, chemotactic, or invasive properties that also increase the ability of cancer cells to disseminate and survive at distant organ sites. These new biomarkers will help predict clinical outcome and point to novel future therapies in metastatic melanoma as well as other cancers.

Cell context-dependent activities of parthenolide in primary and metastatic melanoma cells

BACKGROUND AND PURPOSE

Growing evidence implicates NF-kappaB as an important contributor to metastasis and increased chemoresistance of melanoma. Here, we report the effects of parthenolide on either untreated, cisplatin- or TNFalpha-treated melanoma cell lines A375, 1205Lu and WM793, exhibiting different levels of constitutive NF-kappaB activity.

EXPERIMENTAL APPROACH

Electrophoretic mobility shift assay was used to assess changes in NF-kappaB activity, and real-time PCR to evaluate expression of NF-kappaB-regulated genes. Cell cycle arrest and apoptosis were assessed by flow cytometry. Cell death was also visualized by fluorescence microscopy. Migration was determined by scratch assay and invasiveness by Matrigel assay.

KEY RESULTS

Parthenolide suppressed both constitutive and induced NF-kappaB activity in melanoma cells. This was accompanied by down-regulation of cancer-related genes, with NF-kappaB-binding sites in their promoters, including: Bcl-X(L), survivin, cyclin D1, interleukin 8 and matrix metalloproteinase 9. When the various effects of 6 microM parthenolide were compared, apoptosis associated with loss of mitochondrial membrane potential was most efficiently induced in 1205Lu cells, cell cycle arrest in G(0)/G(1) phase was observed in WM793 cells, and high metastatic potential was markedly reduced in A375 cells. These findings not only reflected differences between melanoma cell lines in basal expression of NF-kappaB-regulated genes, but also suggested other parthenolide targets involved in cell cycle progression, migration, invasiveness and survival.

CONCLUSIONS

Inhibition of constitutive and therapeutically induced NF-kappaB pathway by parthenolide might be useful in the treatment of melanoma, although the diversity of changes induced in melanoma cells with different genetic backgrounds indicate context-dependent poly-pharmacological properties of this compound.

Transiently entrapped circulating tumor cells interact with neutrophils to facilitate lung metastasis development

It is unknown why only a minority of circulating tumor cells trapped in lung capillaries form metastases and involvement of immune cells remains uncertain. A novel model has been developed in this study showing that neutrophils regulate lung metastasis development through physical interaction and anchoring of circulating tumor cells to endothelium. Human melanoma cells were i.v. injected into nude mice leading to the entrapment of many cancer cells; however, 24 hours later, very few remained in the lungs. In contrast, injection of human neutrophils an hour after tumor cell injection increased cancer cell retention by approximately 3-fold. Entrapped melanoma cells produced and secreted high levels of a cytokine called interleukin-8 (IL-8), attracting neutrophils and increasing tethering beta(2) integrin expression by 75% to 100%. Intercellular adhesion molecule-1 on melanoma cells and beta(2) integrin on neutrophils interacted, promoting anchoring to vascular endothelium. Decreasing IL-8 secretion from melanoma cells lowered extracellular levels by 20% to 50%, decreased beta(2) integrin on neutrophils by approximately 50%, and reduced neutrophil-mediated extravasation by 25% to 60%, resulting in approximately 50% fewer melanoma cells being tethered to endothelium and retained in lungs. Thus, transendothelial migration and lung metastasis development decreased by approximately 50%, showing that targeting IL-8 in melanoma cells has the potential to decrease metastasis development by disrupting interaction with neutrophils.

Tumor cell extravasation mediated by leukocyte adhesion is shear rate dependent on IL-8 signaling

To complete the metastatic journey, cancer cells have to disseminate through the circulation and extravasate to distal organs. However, the extravasation process, by which tumor cells leave a blood vessel and invade the surrounding tissue from the microcirculation, remains poorly understood at the molecular level. In this study, tumor cell adhesion to the endothelium (EC) and subsequent extravasation were investigated under various flow conditions. Results have shown polymorphonuclear neutrophils (PMNs) facilitate melanoma cell adhesion to the EC and subsequent extravasation by a shear-rate dependent mechanism. Melanoma cell-PMN interactions are mediated by the binding between intercellular adhesion molecule-1 (ICAM-1) on melanoma cells and beta2 integrins on PMNs. In addition, the fluid convection affects the extent of activation of beta2 integrins on PMNs by endogenously secreted interleukin 8 (IL-8) within the tumor microenvironment. Results also indicate that shear rate affects the binding kinetics between PMNs and melanoma cells, which may contribute to the shear-rate dependence of melanoma extravasation in a shear flow when mediated by PMNs.

p38 MAP kinase is necessary for melanoma-mediated regulation of VE-cadherin disassembly

Vascular endothelial (VE)-cadherin is localized to the endothelial borders and the adherens junctions, which are regulated by changes in mitogen-activated protein (MAP) kinases, GTPases, and intracellular calcium. We previously showed that melanoma cells induce VE-cadherin disassembly through contact with human umbilical vein endothelial cells in coculture. However, the exact mechanism by which melanoma cells signal endothelial cells to induce VE-cadherin junction disassembly is not well understood. In this study, VE-cadherin junction disassembly was further examined under fluorescence microscopy. We found that melanoma-induced VE-cadherin junction disassembly and upregulation of p38 MAP kinase in endothelial cells is regulated by both soluble factors from melanomas, particularly interleukin (IL)-8, IL-6, and IL-1beta, and through vascular cell adhesion molecule-1. Neutralizing melanoma-secreted soluble factors reduced endothelial gap formation. Endothelial cells transfected with MAP kinase kinase 6, a direct activator of p38 MAP kinase, increased VE-cadherin-mediated gap formation, facilitating melanoma transendothelial migration. In contrast, endothelial cells transfected with small-interfering RNA against p38 MAP kinase expression largely prevented melanoma transendothelial migration in Boyden chamber experiments. These findings indicate that p38 MAP kinase proteins regulate VE-cadherin junction disassembly, facilitating melanoma migration across endothelial cells.

Immunoediting of leukocyte functions within the tumor microenvironment promotes cancer metastasis development

Attachment of tumor cells to the endothelium (EC) under flow conditions is critical for migration of tumor cells out of the vascular system to establish metastases. We found that neutrophils (PMN) increased melanoma cell extravasation. Endogenous IL-8 liberated from melanoma cells or from PMN induced by melanoma cells contributed to PMN-facilitated melanoma cell arrest on the EC in the microcirculation. Functional blocking of IL-8 receptors on PMN or neutralizing soluble IL-8 in the tumor circulation decreased the level of CD11b/CD18 up-regulation on PMN and subsequently reduced melanoma cell extravasation. We also found that targeting mutant V600EB-Raf interrupted melanoma cell extravasation in vitro and subsequent lung metastasis development in vivo. B-Raf encodes a RAS-regulated kinase that mediates cell growth and malignant transformation kinase pathway activation. Results showed that inhibition of V600EB-Raf reduced IL-8 secretion from melanoma cells and reduced the capacity of IL-8 production from the tumor microenvironment involving PMN. Furthermore, reduction in intercellular adhesion molecule-1 (ICAM-1) expression on melanoma cells was found after V600EB-Raf knockdown. These results provide new evidence for the complex role of secreted chemokine and PMN-melanoma adhesion in the recruitment of metastatic cancer cells to the EC, which are significant in fostering new approaches to cancer treatment through anti-inflammatory therapeutics.

Overexpression of tissue inhibitors of metalloproteinase 2 up-regulates NF-kappaB activity in melanoma cells

Background

Matrix Metalloproteinase functions in the remodeling of the extracellular matrix that is integral for many normal and pathological processes such as morphogenesis, angiogenesis, tissue repair, and tumor invasion. The tissue inhibitor of the metalloproteinase family including the tissue inhibitor of metalloproteinase-2 (TIMP-2) regulates the activity of multifunctional metalloproteinase. It is known that IL-8, the target gene of NF-κB pathway, increases in the melanoma cells. However, it is not clear whether the TIMP-2 expression regulates the NF-κB pathway. In this study, we have used stable melanoma cell lines, parental A2058, A2058T2-1 overexpressing TIMP-2, and A2058T2R-7 underexpressing TIMP-2, to determine the TIMP-2 regulation of the NF-κB activity.

Results

We found that the IL-8 secretion and IL-8 mRNA expression significantly increased in the A2058T2-1 overexpressing TIMP-2. TIMP-2 overexpressed cells had the lower basal level of IκBα, the inhibitor of NF-κB, compared to the parental A2058 cells. The transcriptional NF-κB activity was increased by the TIMP-2 overexpression. In contrast, A2058T2R-7 underexpressing TIMP-2 had the similar NF-κB activity as that in the parental A2058 cell. The apoptotic cells induced by TNF were less in TIMP-2 over-expression cells compared to those in the parental A2058 cells. TIMP-2 over-expression was able to protect cells from apoptosis.

Conclusion

Our data demonstrate that the expression level of TIMP-2 protein can directly modulate the NF-κB pathway in human melanoma cells.