Transforming growth factor-beta1 inhibits tumor growth in a mouse melanoma model by down-regulating the plasminogen activation system

Multiple Endocrine Neoplasia Type 1 Regulates TGFβ-Mediated Suppression of Tumor Formation and Metastasis in Melanoma

Over the past few decades, the worldwide incidence of cutaneous melanoma, a malignant neoplasm arising from melanocytes, has been increasing markedly, leading to the highest rate of skin cancer-related deaths. While localized tumors are easily removed by excision surgery, late-stage metastatic melanomas are refractory to treatment and exhibit a poor prognosis. Consequently, unraveling the molecular mechanisms underlying melanoma tumorigenesis and metastasis is crucial for developing novel targeted therapies. We found that the multiple endocrine neoplasia type 1 (MEN1) gene product Menin is required for the transforming growth factor beta (TGFβ) signaling pathway to induce cell growth arrest and apoptosis in vitro and prevent tumorigenesis in vivo in preclinical xenograft models of melanoma. We further identified point mutations in two MEN1 family members affected by melanoma that led to proteasomal degradation of the MEN1 gene product and to a loss of TGFβ signaling. Interestingly, blocking the proteasome degradation pathway using an FDA-approved drug and RNAi targeting could efficiently restore MEN1 expression and TGFβ transcriptional responses. Together, these results provide new potential therapeutic strategies and patient stratification for the treatment of cutaneous melanoma.

Latent-Transforming Growth Factor β-Binding Protein 1/Transforming Growth Factor β1 Complex Drives Antitumoral Effects upon ERK5 Targeting in Melanoma

Melanoma is the deadliest skin cancer, with a poor prognosis in advanced stages. Available treatments have improved survival, although long-term benefits still are unsatisfactory. The mitogen-activated protein kinase extracellular signal-regulated kinase 5 (ERK5) promotes melanoma growth, and ERK5 inhibition determines cellular senescence and the senescence-associated secretory phenotype. Here, latent-transforming growth factor β-binding protein 1 (LTBP1) mRNA was found to be up-regulated in A375 and SK-Mel-5 BRAFV600E melanoma cells after ERK5 inhibition. In keeping with a key role of LTBP1 in regulating transforming growth factor β (TGF-β), TGF-β1 protein levels were increased in lysates and conditioned media of ERK5-knockdown (KD) cells, and were reduced upon LTBP1 KD. Both LTBP1 and TGF-β1 proteins were increased in melanoma xenografts in mice treated with the ERK5 inhibitor XMD8-92. Moreover, treatment with conditioned media from ERK5-KD melanoma cells reduced cell proliferation and invasiveness, and TGF-β1-neutralizing antibodies impaired these effects. In silico data sets revealed that higher expression levels of both LTBP1 and TGFB1 mRNA are associated with better overall survival of melanoma patients, and that increased LTBP1 or TGF-β1 expression proved a beneficial role in patients treated with anti-PD1 immunotherapy, making a possible immunosuppressive role of LTBP1/TGF-β1 unlikely upon ERK5 inhibition. This study, therefore, identifies additional desirable effects of ERK5 targeting, providing evidence of an ERK5-dependent tumor-suppressive role of TGF-β in melanoma.

Transforming Growth Factor-β/Smad Signaling Inhibits Melanoma Cancer Stem Cell Self-Renewal, Tumor Formation and Metastasis

The secreted protein transforming growth factor-beta (TGFβ) plays essential roles, ranging from cell growth regulation and cell differentiation in both normal and cancer cells. In melanoma, TGFβ acts as a potent tumor suppressor in melanoma by blocking cell cycle progression and inducing apoptosis. In the present study, we found TGFβ to regulate cancer stemness in melanoma through the Smad signaling pathway. We discovered that TGFβ/Smad signaling inhibits melanosphere formation in multiple melanoma cell lines and reduces expression of the CD133+ cancer stem cell subpopulation in a Smad3-dependent manner. Using preclinical models of melanoma, we further showed that preventing Smad3/4 signaling, by means of CRISPR knockouts, promoted both tumorigenesis and lung metastasis in vivo. Collectively, our results define new functions for the TGFβ/Smad signaling axis in melanoma stem-cell maintenance and open avenues for new therapeutic approaches to this disease.

Progression of melanoma is suppressed by targeting all transforming growth factor‑β isoforms with an Fc chimeric receptor

Melanoma is an aggressive type of cancer originating from the skin that arises from neoplastic changes in melanocytes. Transforming growth factor-β (TGF-β) is a pleiotropic cytokine and is known to contribute to melanoma progression by inducing the epithelial-mesenchymal transition (EMT) program and creating an environment that favors tumor progression. There are three TGF-β isoforms, TGF-β1, TGF-β2 and TGF-β3, all of which engage in pro-tumorigenic activities by activating SMAD signaling pathways. All TGF-β isoforms activate signaling pathways by binding to their TGF-β type I (TβRI) and type II (TβRII) receptors. Thus, effective targeting of all TGF-β isoforms is of great importance. In the present study, chimeric proteins comprising the extracellular domains of TβRI and/or TβRII fused with the Fc portion of human immunoglobulin (IgG) were validated in the melanoma context. The Fc chimeric receptor comprising both TβRI and TβRII (TβRI-TβRII-Fc) effectively trapped all TGF-β isoforms. Conversely, TβRII-Fc chimeric receptor, that comprises TβRII only, was able to interact with TGF-β1 and TGF-β3 isoforms, but not with TGF-β2, which is a poor prognostic factor for melanoma patients. Accordingly, it was revealed that TβRI-TβRII-Fc chimeric receptor suppressed the EMT program in melanoma cells in vitro induced by any of the three TGF-β isoforms, as revealed by decreased expression of mesenchymal markers. Conversely, TβRII-Fc chimeric receptor inhibited the EMT program induced by TGF-β1 and TGF-β3. In addition, it was established that tumor growth in subcutaneous mouse melanoma was inhibited by TβRI-TβRII-Fc chimeric receptor indicating that Fc chimeric receptor could be applied to modify the tumor microenvironment (TME) of melanoma. Therefore, designing of Fc chimeric receptors targeting TGF-β signals that affect various components of the TME may result in the development of effective anti-melanoma agents.

Melanoma Progression under Obesity: Focus on Adipokines

Simple Summary

Obesity is a rapidly growing public health problem and the reason for numerous diseases in the human body, including cancer. This article reviews the current knowledge of the effect of molecules secreted by adipose tissue-adipokines on melanoma progression. We also discuss the role of these factors as markers of incidence, metastasis, and melanoma patient survival. Understanding the functions of adipokines will lead to knowledge of whether and how obesity promotes melanoma growth.

Abstract

Obesity is a growing problem in the world and is one of the risk factors of various cancers. Among these cancers is melanoma, which accounts for the majority of skin tumor deaths. Current studies are looking for a correlation between obesity and melanoma. They suspect that a potential cause of its development is connected to the biology of adipokines, active molecules secreted by adipose tissue. Under physiological conditions, adipokines control many processes, including lipid and glucose homeostasis, insulin sensitivity, angiogenesis, and inflammations. However, when there is an increased amount of fat in the body, their secretion is dysregulated. This article reviews the current knowledge of the effect of adipokines on melanoma growth. This work focuses on the molecular pathways by which adipose tissue secreted molecules modify the angiogenesis, migration, invasion, proliferation, and death of melanoma cells. We also discuss the role of these factors as markers of incidence, metastasis, and melanoma patient survival. Understanding the functions of adipokines will lead to knowledge of whether and how obesity promotes melanoma growth. Further studies may contribute to the innovations of therapies and the use of adipokines as predictive and/or prognostic biomarkers.

Metformin: oxidative and proliferative parameters in-vitro and in-vivo models of murine melanoma

Cutaneous melanoma is one of the most lethal cancers because of its increased rate of metastasis and resistance to available therapeutic options. Early studies indicate that metformin has beneficial effects on some types of cancer, including melanoma. To clarify knowledge of the mechanism of action of metformin on this disease, two treatment-based approaches are presented using metformin on melanoma progression: an in-vitro and an in-vivo model. The in-vitro assay was performed for two experimental treatment periods (24 and 48 h) at different metformin concentrations. The results showed that metformin decreased cell viability, reduced proliferation, and apoptosis was a major event 48 h after treating B16F10 cells. Oxidative stress was characterized by the decrease in total thiol antioxidants immediately following 24 h of metformin treatment and showed an increase in lipid peroxidation. The in-vivo model was performed by injecting B16F10 cells into the subcutaneous of C57/BL6 mice. Treatment with metformin began on day 3 and on day 14, the mice were killed. Treatment of mice with metformin reduced tumor growth by 54% of its original volume compared with nontreatment. The decrease in systemic vascular endothelial growth factor, restoration of antioxidants glutathione and catalase, and normal levels of lipid peroxidation indicate an improved outcome for melanoma following metformin treatment, meeting a need for new strategies in the treatment of melanoma.

Integrin β1 activation induces an anti-melanoma host response

TGF-β is a cytokine thought to function as a tumor promoter in advanced malignancies. In this setting, TGF-β increases cancer cell proliferation, survival, and migration, and orchestrates complex, pro-tumorigenic changes in the tumor microenvironment. Here, we find that in melanoma, integrin β1-mediated TGF-β activation may also produce tumor suppression via an altered host response. In the A375 human melanoma cell nu/nu xenograft model, we demonstrate that cell surface integrin β1-activation increases TGF-β activity, resulting in stromal activation, neo-angiogenesis and, unexpectedly for this nude mouse model, increase in the number of intra-tumoral CD8⁺ T lymphocytes within the tumor microenvironment. This is associated with attenuation of tumor growth and long-term survival benefit. Correspondingly, in human melanomas, TGF-β1 correlates with integrin β1/TGF-β1 activation and the expression of markers for vasculature and stromal activation. Surprisingly, this integrin β1/TGF-β1 transcriptional footprint also correlates with the expression of markers for tumor-infiltrating lymphocytes, multiple immune checkpoints and regulatory pathways, and, importantly, better long-term survival of patients. These correlations are unique to melanoma, in that we do not observe similar associations between β1 integrin/TGF-β1 activation and better long-term survival in other human tumor types. These results suggest that activation of TGF-β1 in melanoma may be associated with the generation of an anti-tumor host response that warrants further study.

Suppression of Type I Interferon Signaling Overcomes Oncogene-Induced Senescence and Mediates Melanoma Development and Progression

Oncogene activation induces DNA damage responses and cell senescence. We report a key role of type I interferons (IFNs) in oncogene-induced senescence. IFN signaling-deficient melanocytes expressing activated Braf do not exhibit senescence and develop aggressive melanomas. Restoration of IFN signaling in IFN-deficient melanoma cells induces senescence and suppresses melanoma progression. Additional data from human melanoma patients and mouse transplanted tumor models suggest the importance of non-cell-autonomous IFN signaling. Inactivation of the IFN pathway is mediated by the IFN receptor IFNAR1 downregulation that invariably occurs during melanoma development. Mice harboring an IFNAR1 mutant, which is partially resistant to downregulation, delay melanoma development, suppress metastatic disease, and better respond to BRAF or PD-1 inhibitors. These results suggest that IFN signaling is an important tumor-suppressive pathway that inhibits melanoma development and progression and argue for targeting IFNAR1 downregulation to prevent metastatic disease and improve the efficacy of molecularly target and immune-targeted melanoma therapies.

Correlation of TGF-β1 and oxidative stress in the blood of patients with melanoma: a clue to understanding melanoma progression?

TGF-β1 and oxidative stress are involved in cancer progression, but in melanoma, their role is still controversial. Our aim was to correlate plasma TGF-β1 levels and systemic oxidative stress biomarkers in patients with melanoma, with or without disease metastasis, to understand their participation in melanoma progression. Thirty patients were recruited for melanoma surveillance, together with 30 healthy volunteers. Patients were divided into two groups: Non-metastasis, comprising patients with tumor removal and no metastatic episode for 3 years; and Metastasis, comprising patients with a metastatic episode. The plasmatic cytokines TGF-β1, IL-1 β, and TNF-α were analyzed by ELISA. For oxidative stress, the following assays were performed: malondialdehyde (MDA), advanced oxidation protein products (AOPP) levels, total radical-trapping antioxidant parameter (TRAP) and thiol in plasma, and lipid peroxidation, SOD and catalase activity and GSH in erythrocytes. Patients with a metastatic episode had less circulating TGF-β1 and increased TRAP, thiol, AOPP and lipid peroxidation levels. MDA was increased in both melanoma groups, while catalase, GSH, and IL-1β was decreased in Non-metastasis patients. Significant negative correlations were observed between TGF-β1 levels and systemic MDA, and TGF-β1 levels and systemic AOPP, while a positive correlation was observed between TGF-β1 levels and erythrocyte GSH. Lower levels of TGF-β1 were related to increased oxidative stress in Metastasis patients, reinforcing new evidence that in melanoma TGF-β1 acts as a tumor suppressor, inhibiting tumor relapse. These findings provide new knowledge concerning this cancer pathophysiology, extending the possibilities of investigating new therapies based on this evidence.

Hypoxia inducible factor-1 mediates upregulation of urokinase-type plasminogen activator receptor gene transcription during hypoxia in cervical cancer cells

Hypoxia occurs during development of cervical cancer and is considered to correlate with its invasion. Hypoxia mediates tumor cells to have more invasive property in a variety of cancers. Urokinase plasminogen activator receptor (uPAR) which mediates invasion is considered to be induced by hypoxia. We sought to determine the regulators of uPAR expression during hypoxia in cervical cancer. We showed that cervical cancer cell lines, CaSki and CA, were more invasive under hypoxic condition (1% O2) than under normoxic condition (20% O2) by invasion assays. Using western blot analysis, hypoxia enhanced the endogenous hypoxia-inducible factor (HIF)-1α and uPAR protein expression. uPAR mRNA level was also upregulated by hypoxia using real-time RT-PCR. Overexpression of HIF-1α which is induced by hypoxia activated the transcriptional activity of the uPAR promoter by luciferase assays. HIF-1 protein bound the putative HIF-1 response element on the uPAR promoter using electrophoretic mobility shift analysis, and additional luciferase assays show that this is essential for uPAR transactivation by HIF-1. HIF-1 overexpression enhanced the endogenous uPAR expression and introduction of siRNA for HIF-1α diminishes uPAR expression during hypoxia. These results indicate the upregulation of uPAR by hypoxia in cervical cancer cells is mediated through HIF-1. In cervical cancer tissues, we also demonstrated that uPAR protein expression was detected in cervical cancer but not in normal cervix or cervical intraepithelial neoplasia (CIN) by immunohistopathological staining. Our results provide evidence that regulation of uPAR expression by HIF-1 represents a mechanism for cervical cancer invasion during hypoxia.

The leukemia inhibitory factor (LIF) and p21 mediate the TGFβ tumor suppressive effects in human cutaneous melanoma

BACKGROUND

Cutaneous melanoma is the most lethal skin cancer and its incidence in developed countries has dramatically increased over the past decades. Localized tumors are easily treated by surgery, but advanced melanomas lack efficient treatment and are associated with very poor outcomes. Thus, understanding the processes underlying melanoma development and progression is critical. The Transforming Growth Factor beta (TGFβ) acts as a potent tumor suppressor in human melanoma, by inhibiting cell growth and preventing cellular migration and invasion.

METHODS

In this study, we aimed at elucidating the molecular mechanisms underlying TGFβ-mediated tumor suppression. Human cutaneous melanoma cell lines, derived from different patients, were used to assess for cell cycle analysis, apoptosis/caspase activity and cell migration. Techniques involved immunoblotting, immunohistochemistry, real time PCR and luciferase reporter assays.

RESULTS

We found the leukemia inhibitory factor (LIF) to be strongly up-regulated by TGFβ in melanoma cells, defining LIF as a novel TGFβ downstream target gene in cutaneous melanoma. Interestingly, we also showed that TGFβ-mediated LIF expression is required for TGFβ-induced cell cycle arrest and caspase-mediated apoptosis, as well as for TGFβ-mediated inhibition of cell migration. Moreover, we found that TGFβ-mediated LIF expression leads to activation of transcription of the cell cycle inhibitor p21 in a STAT3-dependent manner, and further showed that p21 is required for TGFβ/LIF-mediated cell cycle arrest and TGFβ-induced gene activation of several pro-apoptotic genes.

CONCLUSIONS

Together, our results define the LIF/p21 signaling cascade as a novel tumor suppressive-like pathway in melanoma, acting downstream of TGFβ to regulate cell cycle arrest and cell death, further highlight new potential therapeutic strategies for the treatment of cutaneous melanoma.

Antiangiogenesis, loss of cell adhesion and apoptosis are involved in the antitumoral activity of Proteases from V. cundinamarcensis (C. candamarcensis) in murine melanoma B16F1

The proteolytic enzymes from V. cundinamarcensis latex, (P1G10), display healing activity in animal models following various types of lesions. P1G10 or the purified isoforms act as mitogens on fibroblast and epithelial cells by stimulating angiogenesis and wound healing in gastric and cutaneous ulcers models. Based on evidence that plant proteinases act as antitumorals, we verified this effect on a murine melanoma model. The antitumoral effect analyzed mice survival and tumor development after subcutaneous administration of P1G10 into C57BL/6J mice bearing B16F1 low metastatic melanoma. Possible factors involved in the antitumoral action were assessed, i.e., cytotoxicity, cell adhesion and apoptosis in vitro, haemoglobin (Hb), vascular endothelial growth factor (VEGF), tumor growth factor-β (TGF-β), tumor necrosis factor-α (TNF-α) content and N-acetyl-glucosaminidase (NAG) activity. We observed that P1G10 inhibited angiogenesis measured by the decline of Hb and VEGF within the tumor, and TGF-β displayed a non-significant increase and TNF-α showed a minor non-significant reduction. On the other hand, there was an increase in NAG activity. In treated B16F1 cells, apoptosis was induced along with decreased cell binding to extracellular matrix components (ECM) and anchorage, without impairing viability.

Resistance of MMP9 and TIMP1 to endotoxin tolerance

Inflammatory cytokines activate tissue collagenases such as matrix metalloproteinases (MMPs). MMPs are antagonized by tissue inhibitors of metalloproteinases (TIMPs) that attempt to regulate excessive collagenase activity during inflammatory conditions. During chronic inflammatory conditions, induction of endotoxin tolerance negatively regulates the cytokine response in an attempt to curtail excessive host tissue damage. However, little is known about how downregulation of inflammatory cytokines during endotoxin tolerance regulates MMP activities. In this study, human monocyte-derived macrophages were either sensitized or further challenged to induce tolerance with lipopolysaccharide (LPS) from Porphyromonas gingivalis (PgLPS) or Escherichia coli (EcLPS). Inflammatory cytokines, such as TNF-α and IL-1β, and levels of MMP9 and TIMP1 were analyzed by a combination of cytometric bead array, western blot/gelatin zymography and real-time RT-PCR. Functional blocking with anti-TLR4 but not with anti-TLR2 significantly downregulated TNF-α and IL-1β. However, MMP9 levels were not inhibited by toll-like receptor (TLR) blocking. Interestingly, endotoxin tolerance significantly upregulated TIMP1 relative to MMP9 and downmodulated MMP9 secretion and its enzymatic activity. These results suggest that regulatory mechanisms such as induction of endotoxin tolerance could inhibit MMP activities and could facilitate restoring host tissue homeostasis.

Transforming growth factor-Beta and urokinase-type plasminogen activator: dangerous partners in tumorigenesis-implications in skin cancer

Transforming growth factor-beta (TGF-β) is a pleiotropic factor, with several different roles in health and disease. TGF-β has been postulated as a dual factor in tumor progression, since it represses epithelial tumor development in early stages, whereas it stimulates tumor progression in advanced stages. During tumorigenesis, cancer cells acquire the capacity to migrate and invade surrounding tissues and to metastasize different organs. The urokinase-type plasminogen activator (uPA) system, comprising uPA, the uPA cell surface receptor, and plasminogen-plasmin, is involved in the proteolytic degradation of the extracellular matrix and regulates key cellular events by activating intracellular signal pathways, which together allow cancer cells to survive, thus, enhancing cell malignance during tumor progression. Due to their importance, uPA and its receptor are tightly transcriptionally regulated in normal development, but are deregulated in cancer, when their activity and expression are related to further development of cancer. TGF-β regulates uPA expression in cancer cells, while uPA, by plasminogen activation, may activate the secreted latent TGF-β, thus, producing a pernicious cycle which contributes to the enhancement of tumor progression. Here we review the specific roles and the interplay between TGF-β and uPA system in cancer cells and their implication in skin cancer.

The Dual Role of TGFβ in Human Cancer: From Tumor Suppression to Cancer Metastasis

The transforming growth factor-beta (TGFβ) superfamily encompasses widespread and evolutionarily conserved polypeptide growth factors that regulate and orchestrate growth and differentiation in all cell types and tissues. While they regulate asymmetric cell division and cell fate determination during early development and embryogenesis, TGFβ family members play a major regulatory role in hormonal and immune responses, cell growth, cell death and cell immortalization, bone formation, tissue remodeling and repair, and erythropoiesis throughout adult life. The biological and physiological functions of TGFβ, the founding member of this family, and its receptors are of central importance to human diseases, particularly cancer. By regulating cell growth, death, and immortalization, TGFβ signaling pathways exert tumor suppressor effects in normal cells and early carcinomas. Thus, it is not surprising that a high number of human tumors arise due to mutations or deletions in the genes coding for the various TGFβ signaling components. As tumors develop and progress, these protective and cytostatic effects of TGFβ are often lost. TGFβ signaling then switches to promote cancer progression, invasion, and tumor metastasis. The molecular mechanisms underlying this dual role of TGFβ in human cancer will be discussed in depth in this paper, and it will highlight the challenge and importance of developing novel therapeutic strategies specifically aimed at blocking the prometastatic arm of the TGFβ signaling pathway without affecting its tumor suppressive effects.

TGF-beta inhibits human cutaneous melanoma cell migration and invasion through regulation of the plasminogen activator system

Over the past decades, the incidence of cutaneous melanoma in developed countries has increased faster than any other cancer. Although most patients have localized disease at the time of diagnosis and are cured by surgical excision of the primary tumor, melanoma can be highly malignant and the survival dramatically decreases for advanced stage melanomas. It is thus necessary to understand the progression of this disease. Cell migration and invasion promote tumor metastasis, the major cause of melanoma cancer morbidity and death. In this study, we investigated the role of the TGFβ/Smad signaling pathway in melanoma tumor progression and found TGFβ to potently inhibit both cell migration and invasion in human melanoma cell lines, established from different patients. Furthermore, we elucidated the molecular mechanisms by which TGFβ exerts its effects and found the plasminogen activation system (PAS) to play a central role in the regulation of these effects. We found TGFβ to strongly up-regulate the Plasminogen Activator Inhibitor-1 (PAI-1) in melanoma cells, leading to reduced plasmin generation and activity and, in turn to inhibition of cell migration and invasion. Together, our results define TGFβ as a potent suppressor of tumor progression in cutaneous melanoma, inhibiting both cell migration and invasion.

A systems biology analysis of metastatic melanoma using in-depth three-dimensional protein profiling

Melanoma is an excellent model to study molecular mechanisms of tumor progression because melanoma usually develops through a series of architecturally and phenotypically distinct stages that are progressively more aggressive, culminating in highly metastatic cells. In this study, we used an in-depth, 3-D protein level, comparative proteome analysis of two genetically, very closely related melanoma cell lines with low- and high-metastatic potentials to identify proteins and key pathways involved in tumor progression. This proteome comparison utilized fluorescent tagging of cell lysates followed by microscale solution IEF prefractionation and subsequent analysis of each fraction on narrow-range 2-D gels. LC-MS/MS analysis of gel spots exhibiting significant abundance changes identified 110 unique proteins. The majority of observed abundance changes closely correlate with biological processes central to cancer progression, such as cell death and growth and tumorigenesis. In addition, the vast majority of protein changes mapped to six cellular networks, which included known oncogenes (JNK, c-myc, and N-myc) and tumor suppressor genes (p53 and transforming growth factor-β) as critical components. These six networks showed substantial connectivity, and most of the major biological functions associated with these pathways are involved in tumor progression. These results provide novel insights into cellular pathways implicated in melanoma metastasis.

Elastin-derived peptides enhance melanoma growth in vivo by upregulating the activation of Mcol-A (MMP-1) collagenase

Background:

Elastin peptides possess several biological activities and in vitro data suggest they could be involved in the early phase of melanoma growth.

Methods:

Using diverse in vitro and in vivo techniques (cell proliferation, invasion and migration assays, zymography, western blots, collagen degradation assay, reverse transcription PCR, melanoma allographs and immunohistochemistry), we analysed the effect of elastin-derived peptides (EDPs) on B16F1 melanoma growth and invasion, as well as on the proteolytic systems involved.

Results:

We found that EDPs dramatically promote in vivo tumour development of B16F1 melanoma, as well as their in vitro migration and invasion. The inhibition of serine proteases and matrix metalloproteinases (MMPs) activities, by aprotinin and galardin, respectively, demonstrated that these enzymes were involved in these processes. However, we found that EDPs did not increase urokinase-type plasminogen activator, tissue-type plasminogen activator or MMP-2 expression and/or activation, neither in vitro nor in vivo. Nevertheless, we observed a strong increase of pro-MMP-9 secretion in EDPs-treated tumours and, more importantly, an increase in the expression and activation of the murine counterpart of MMP-1, named murine collagenase-A (Mcol-A). Moreover, we show that plasminogen system inhibition decreases collagen degradation by this enzyme. Finally, the use of a specific blocking antibody against Mcol-A abolished EDP-induced B16F1 invasion in vitro, showing that this MMP was directly involved in this process.

Conclusion:

Our data show that in vivo, EDPs are involved in melanoma growth and invasion and reinforced the concept of elastin fragmentation as a predictive factor.

A t-butyloxycarbonyl-modified Wnt5a-derived hexapeptide functions as a potent antagonist of Wnt5a-dependent melanoma cell invasion

The influential role of Wnt5a in tumor progression underscores the requirement for developing molecules that can target Wnt5a-mediated cellular responses. In the aggressive skin cancer, melanoma, elevated Wnt5a expression promotes cell motility and drives metastasis. Two approaches can be used to counteract these effects: inhibition of Wnt5a expression or direct blockade of Wnt5a signaling. We have investigated both options in the melanoma cell lines, A2058 and HTB63. Both express Frizzled-5, which has been implicated as the receptor for Wnt5a in melanoma cells. However, only the HTB63 cell line expresses and secretes Wnt5a. In these cells, the cytokine, TGFbeta1, controlled the expression of Wnt5a, but due to the unpredictable effects of TGFbeta1 signaling on melanoma cell motility, targeting Wnt5a signaling via TGFbeta1 was an unsuitable strategy to pursue. We therefore attempted to target Wnt5a signaling directly. Exogenous Wnt5a stimulation of A2058 cells increased adhesion, migration and invasion, all crucial components of tumor metastasis, and the Wnt5a-derived N-butyloxycarbonyl hexapeptide (Met-Asp-Gly-Cys-Glu-Leu; 0.766 kDa) termed Box5, abolished these responses. Box5 also inhibited the basal migration and invasion of Wnt5a-expressing HTB63 melanoma cells. Box5 antagonized the effects of Wnt5a on melanoma cell migration and invasion by directly inhibiting Wnt5a-induced protein kinase C and Ca(2+) signaling, the latter of which we directly demonstrate to be essential for cell invasion. The Box5 peptide directly inhibits Wnt5a signaling, representing an approach to anti-metastatic therapy for otherwise rapidly progressive melanoma, and for other Wnt5a-stimulated invasive cancers.

RNAi targeting urokinase-type plasminogen activator receptor inhibits metastasis and progression of oral squamous cell carcinoma in vivo

It has been admitted that urokinase-type plasminogen activator receptor (u-PAR) is overexpressed in many human malignant tumors including oral squamous cell carcinoma (OSCC) and plays an important role in a variety of cancer key cellular events as a versatile signaling orchestrator. In our study, a retroviral vector expressing u-PAR-specific siRNA was injected into OSCC xenografts of nude mice to observe its inhibitory effects on OSCC. Our data demonstrate that siRNA targeting u-PAR markedly suppressed tumor growth, reduced the expression of proliferation-related gene, Ki-67 and increased cell apoptosis, accompanying with the efficient and specific inhibition of endogenous u-PAR expression in OSCC. More importantly, the mRNA and protein expression of MMP-2, MMP-9, VEGF-C, VEGF-D and VEGFR-3 that are intimately involved in oral cancer invasion and metastasis, was simultaneously downregulated significantly as determined by quantitative real-time RT-PCR, Western blot and immunohistochemistry; and Gelatin and fibrin zymography showed that MMP-9, MMP-2 and u-PA enzymatic activities were significantly reduced in u-PAR-specific siRNA group, compared to those in control groups. In addition, the expression of MDR-1 gene related to drug resistance was obviously inhibited by silencing of u-PAR. These findings suggest that RNAi targeting u-PAR could effectively inhibit the metastasis and progression of OSCC in vivo. Thus, it may be used as a potent and specific therapy for oral cancer, especially in inhibiting and preventing cancer cell invasion and metastasis.

Regulatory expression of genes related to metastasis by TGF-beta and activin A in B16 murine melanoma cells

TGF-beta induces epithelial-mesenchymal transition, which occurs during tumor cell invasiveness in pathological state, in limited cells. As a first step to understand the role of TGF-beta and the structurally related activin during melanoma metastasis, expression of metastasis-related genes was examined in murine melanoma cells. Treatment with TGF-beta1 or activin A down-regulated E-cadherin in B16 cells in a dose-dependent manner. In epithelial cells, TGF-beta-induced high mobility group A2 (HMGA2) gene product is suggested to down-regulate E-cadherin through up-regulation of zinc-finger transcription factors Slug and Snail, and basic helix-loop-helix transcription factor Twist. Unlike the regulation in epithelial cells, TGF-beta1 treatment rather decreased mRNA expression of HMGA2, indicating a distinct mechanism on TGF-beta/activin-induced down-regulation. Transfection of double-stranded interfering RNA (dsRNAi) for activin receptor-like kinase (ALK) type I receptors revealed that ALK5, a prototype of TGF-beta receptor, mainly transmits TGF-beta signals on the E-cadherin down-regulation at the mRNA level, and that a prototype receptor ALK4 elicited the activin effect. TGF-beta/activin potentiated down-regulation of E-cadherin and HMGA2 also in B16 sublines that are susceptible to metastasis. However, the extent of down-regulation tended to be smaller, and less Smad2, a signal mediator for TGF-beta/activin, was phosphorylated in response to the ligand, resulting from less expression of type I receptors in the B16 sublines. These results suggest that the receptor expression level determines strength of the signals for TGF-beta/activin through phosphorylation of Smad2, which explains pluripotency of the ligand family partly.

The molecular basis of melanomagenesis and the metastatic phenotype

The last two decades have seen spectacular advances in our understanding of the biology of melanoma and, in particular, have elucidated the mechanisms operative in disease initiation and progression. With respect to the former, the genetics of melanoma and in particular the impact of genetic defects on dysregulation of the cell cycle are key issues in malignant transformation and are a major focus of this review. With respect to the latter, consideration also is given to the acquisition of growth factor autonomy and the capacity for invasion and metastasis from the standpoint of cell adhesion, motility, and matrix digestion. These events have specific morphologic correlates that will be briefly addressed. Where relevant, we will address certain of the modern pharmacogenetic strategies that flow from these novel observations concerning melanoma biology.

Characterization and inhibition of fibrin hydrogel-degrading enzymes during development of tissue engineering scaffolds

The goal of articular cartilage tissue engineering is to provide cartilaginous constructs to replace abnormal cartilage. We have evaluated the chondroprogenitor clonal cell line RCJ3.1C5.18 (C5.18) as a model to guide the development of appropriate scaffolds for tissue engineering. Rapid degradation of fibrin hydrogels was observed after encapsulation of C5.18 cells. The enzymes responsible for this fibrin gel breakdown were characterized to control their activity and regulate gel stability. Western blotting, confirming zymography, revealed bands due to matrix metalloproteinases (MMP-2, MMP-3) that are secreted concomitantly with fibrin hydrogels breakdown. High plasmin activity was detected in conditioned media during hydrogel breakdown but not in the confluent cells before encapsulation. Reverse transcriptase polymerase chain reaction indicated the expression of MMP-2, -3, and -9 and plasminogen in the cells. MMP-9 was 100 times higher at day 1, whereas MMP-2 started to increase and reached its maximum level by day 7. Aprotinin, a known serine protease inhibitor, and galardin (GM6001), a potent MMP inhibitor, in combination or separately, prevented the breakdown of fibrin-C5.18 hydrogels, whereas only the combination of both promoted the accumulation of extracellular matrix. These findings suggest that plasmin and MMPs contribute independently to fibrin hydrogel breakdown, but that either enzyme can achieve extracellular matrix breakdown.

Reduced pSmad2 immunodetection correlates with increased primary melanoma thickness

Cutaneous melanoma is the most aggressive of cutaneous neoplasms. Identifying patients with an increased risk for the development of metastases is critical. This study investigates phospho-Smad2, a central factor of the transforming growth factor beta pathway, on formalin-fixed, paraffin-embedded tissues from 60 primary cutaneous melanomas (Breslow >1 mm), for its candidacy for being a prognostic marker in primary cutaneous melanoma. Phospho-Smad2 positivity was assessed for correlation with clinical parameters including Breslow index, melanoma type, survival, development of metastases, sentinel lymph node status and age. Phospho-Smad2 positivity was not associated with survival or development of metastases, suggesting that it would not be a useful prognostic marker. Despite this, we found phospho-Smad2 positivity to be correlated with low tumour thickness, indicating that as the primary tumour grows there is an increased inhibition of transforming growth factor beta signalling resulting in suppressed Smad2 phosphorylation. Additionally, phosphorylation of Smad2 in neighbouring melanoma cells and keratinocytes was interrelated, which is a further indication that Smad2 phosphorylation in primary melanoma is affected by local area microenvironmental factors. We hypothesize that the observed decrease in transforming growth factor beta signalling in thicker primary melanomas is due to the increased production of signalling inhibitors.

Nestin expression in cutaneous melanomas and melanocytic nevi

BACKGROUND

Nestin is one of the intermediate filaments that are expressed in proliferating neural progenitor cells during development of the central nervous system (CNS) and peripheral nervous system. Postnatal re-expression of the protein occurs mainly under pathological conditions, including injury and neoplasia. In this study, nestin expression was detected in both benign and malignant melanocytic skin lesions and its diagnostic relevance was then evaluated.

METHODS

Altogether 139 bioptic tissue samples consisting of 42 nodular melanomas, 32 superficial spreading melanomas, 12 metastatic melanomas, 10 dysplastic nevi and 43 common melanocytic intradermal and dermoepidermal nevi were analysed using indirect immunohistochemical staining.

RESULTS

We demonstrated that nestin immunostaining was significantly increased in melanomas where it correlated with more advanced stages of the disease.

CONCLUSION

We conclude that expression of the intermediate filament protein nestin might be an indicator of tumor dedifferentiation and more aggressive behaviour. Furthermore, we suggest that nestin might be a relevant marker of tumorous and non-tumorous angiogenesis.

Endogenous Growth Factors as Cosmeceuticals

BACKGROUND

Research into the pathophysiology of photodamaged skin has revealed correlations with certain aspects of acute and chronic wound healing. In wound healing, growth factors accumulate at the wound site and interact synergistically to initiate and coordinate wound healing.

OBJECTIVES

To review the effects of topical growth factors in wound healing and their potential use in treating photodamaged skin.

METHODS

A mixture of multiple growth factors derived from human fibroblasts was applied topically to 14 patients twice daily for 60 days to stimulate the remodeling phase of wound healing.

RESULTS

A total of 78.6% of patients with photodamaged skin showed clinical improvement at 60 days. New collagen formation increased by 37%, and epidermal thickening increased by 27%.

CONCLUSIONS

These data, as well as other studies of growth factors in wound healing, demonstrate positive cosmetic and clinical outcomes of topical application of growth factors for the treatment of photodamaged skin.

Transforming Growth Factor-β1 Induces Tissue Inhibitor of Metalloproteinase-1 Expression via Activation of Extracellular Signal-Regulated Kinase and Sp1 in Human Fibrosarcoma Cells

The net balance of matrix metalloproteinases (MMP) and tissue inhibitor of metalloproteinases (TIMP) system has been known to be a key factor in tumor cell invasion. In the present study, we investigated the molecular mechanisms of anti-invasive and antimigrative activity of transforming growth factor (TGF)-beta1 on HT1080 human fibrosarcoma cells. In in vitro Matrigel invasion and Transwell migration assays, TGF-beta1 dose-dependently inhibited the invasion and migration of HT1080 cells, respectively. Gelatin zymography, Western blot, and real-time PCR analysis showed that TGF-beta1 enhanced the expression and secretion of MMP-2, TIMP-1, and, to a lesser degree, MMP-9 but not membrane type 1-MMP and TIMP-2. The addition of recombinant TIMP-1 protein reduced the Matrigel invasion and Transwell migration of HT1080 cells, similar to TGF-beta1. Because augmentation of TIMP-1 might be the major factor for the anti-invasive and antimigrative activity of TGF-beta1, we investigated possible molecular mechanisms responsible for the expression of TIMP-1 induced by TGF-beta1. Treatment of HT1080 cells with TGF-beta1 rapidly phosphorylated three mitogen-activated protein kinases [MAPK; extracellular signal-regulated kinase 1/2 (ERK1/2), p38, and c-Jun NH2-terminal kinase] and Akt. Among these kinases, the inhibition of only ERK1/2 pathway by PD98059, a specific inhibitor of MAPK/ERK kinase(MEK)-1, and transfection of dominant-negative MEK 1 effectively blocked the TIMP-1 induction by TGF-beta1. Mithramycin, a specific inhibitor of Sp1 transcription factor, but not curcumin, an inhibitor of activator protein-1, and transfection of Sp1 small interfering RNA significantly inhibited the TGF-beta1-induced expression of TIMP-1. In addition, electrophoretic mobility shift assay showed that TGF-beta1 up-regulated Sp1 DNA-binding activity, and PD98059 and mithramycin effectively inhibited these events. Finally, pretreatment of HT1080 cells with PD98059 and mithramycin, but not curcumin, restored the invasive activity of these cells. Taken together, these data suggest that TGF-beta1 modulates the net balance of the MMPs/TIMPs the systems in HT1080 cells for anti-invasion and antimigration by augmenting TIMP-1 through ERK1/2 pathway and Sp1 transcription factor.

Hammerhead ribozyme-mediated silencing of the mutant fibrillin-1 of tight skin mouse: insight into the functional role of mutant fibrillin-1

The tight skin (Tsk/+) mouse is a model for fibrotic disorders. The genetic defect in the Tsk/+ is an in-frame duplication between exons 17 and 40 of the fibrillin-1 gene which gives rise to a large transcript and protein. Mice homozygous for the mutation die in utero, whereas heterozygotes survive and spontaneously develop connective tissue disease. In this study, we generated hammerhead ribozymes directed against the mutant fibrillin-1 transcript. A partially mispairing ribozyme was the most effective vehicle to cleave the mutant transcript without undesired cleavage of wild type transcripts, as shown by cell-free RNA cleavage and cleavage in cell lines harboring the ribozyme, by RT-PCR, Northern and Western Blotting. Global gene expression profiling using oligonucleotide microarrays showed the expected reduction in fibrillin-1 mRNA, and down-regulation of several gene cohorts in ribozyme harboring TskR1 cells compared to Tsk/+ cells. Two of the functional clusters included genes regulating extracellular matrix such as connective tissue growth factor, serpine-1 (plasminogen activator inhibitor-1) and TIMP-1 and TIMP-3, and those involved in cytoskeletal organization and myofibroblast formation including calponins and transgelin. Ribozyme-mediated inhibition was confirmed by Western Blot and functional analysis using cell-reporter systems and remodeling of three dimensional collagen gels. Our results underline the therapeutic potential of hammerhead ribozymes in dominant negative defects and suggest that changes in microfibril architecture brought about by fibrillin-1 mutation lead to a complex disease phenotype.

Differential regulation of metzincins in experimental chronic renal allograft rejection: Potential markers and novel therapeutic targets

Chronic renal allograft rejection is characterized by alterations in the extracellular matrix compartment and in the proliferation of various cell types. These features are controlled, in part by the metzincin superfamily of metallo-endopeptidases, including matrix metalloproteinases (MMPs), a disintegrin and metalloproteinase (ADAM) and meprin. Therefore, we investigated the regulation of metzincins in the established Fisher to Lewis rat kidney transplant model. Studies were performed using frozen homogenates and paraffin sections of rat kidneys at day 0 (healthy controls) and during periods of chronic rejection at day +60 and day +100 following transplantation. The messenger RNA (mRNA) expression was examined by Affymetrix Rat Expression Array 230A GeneChip and by real-time Taqman polymerase chain reaction analyses. Protein expression was studied by zymography, Western blot analyses, and immunohistology. mRNA levels of MMPs (MMP-2/-11/-12/-14), of their inhibitors (tissue inhibitors of metalloproteinase (TIMP)-1/-2), ADAM-17 and transforming growth factor (TGF)-beta1 significantly increased during chronic renal allograft rejection. MMP-2 activity and immunohistological staining were augmented accordingly. The most important mRNA elevation was observed in the case of MMP-12. As expected, Western blot analyses also demonstrated increased production of MMP-12, MMP-14, and TIMP-2 (in the latter two cases as individual proteins and as complexes). In contrast, mRNA levels of MMP-9/-24 and meprin alpha/beta had decreased. Accordingly, MMP-9 protein levels and meprin alpha/beta synthesis and activity were downregulated significantly. Members of metzincin families (MMP, ADAM, and meprin) and of TIMPs are differentially regulated in chronic renal allograft rejection. Thus, an altered pattern of metzincins may represent novel diagnostic markers and possibly may provide novel targets for future therapeutic interventions.

Proliferation of Pulmonary Interstitial Fibroblasts Is Mediated by Transforming Growth Factor-β1-induced Release of Extracellular Fibroblast Growth Factor-2 and Phosphorylation of p38 MAPK and JNK

Idiopathic pulmonary fibrosis (IPF; a progressive lung disease) is characterized by parenchymal remodeling with enlarged air spaces called honeycomb cysts and palisades of fibroblasts called fibroblast foci. In IPF, lung epithelial cells covering honeycomb cysts and fibroblast foci aberrantly express the active conformation of the potent fibrogenic cytokine transforming growth factor-beta1 (TGF-beta1). Using explanted rat lung slices, we transfected alveolar epithelial cells with the retrovirus pMX containing a site-directed mutation in which Cys223 and Cys225 were substituted with serines, resulting in release of biologically active TGF-beta1 and fibroblast proliferation and remodeling that resembled IPF. Fibroblasts obtained from transfected explants and in culture for 6 weeks incorporated 6.59 +/- 1.55-fold more [3H]thymidine compared with control fibroblasts without transfection or fibroblasts obtained from transfected explants cultured with antibody to fibroblast growth factor-2 (FGF-2). Primary lung fibroblasts obtained from normal rat lungs cultured with TGF-beta1 expressed increased levels of phosphorylated p38 MAPK and JNK, but not ERK1/2. The presence of TGF-beta1 caused an immediate release of extracellular FGF-2 from primary pulmonary fibroblasts; and in the presence of anti-FGF-2 antibody, phosphorylated p38 MAPK and JNK were abrogated. TGF-beta inhibits cell proliferation by suppression of c-Myc and induction of p15INK46, p21CIP1, or p27KIP. Fibroblasts cultured with TGF-beta1 showed no regulation of c-Myc or induction of p15INK46, p21CIP1,or p27KIP. These findings suggest that pulmonary fibroblasts may not respond to the anti-proliferative effects of TGF-beta1, but proliferate in response to TGF-beta1 indirectly by the release of FGF-2, which induces phosphorylation of p38 MAPK and JNK.

Control of melanoma progression by various matrikines from basement membrane macromolecules

Many biological processes such as cell differentiation, cell migration or gene expression are tightly controlled by cell-cell interactions or by various cytokines. During tumor progression, cancer cells are in contact with extracellular matrix (ECM) macromolecules involving specific receptors such as integrins. The different stages of tumor progression, and mainly the proteolytic cascades implicated in extracellular matrix degradation and cell migration, may be controlled by the extracellular matrix macromolecules or by domains released by directed and limited proteolysis of these molecules. In this review, we summarise the biological effects of various peptides, named matrikines, derived from basement membranes (BM) components, such as laminins (LN), proteoglycans or collagens. These peptides may control tumor progression by regulating the proteolytic cascades leading to cancer cell dissemination and metastasis.

Relationship between urokinase-type plasminogen activator receptor and vascular endothelial growth factor expression and metastasis of gallbladder cancer

AIM: To investigate the relationship of urokinase type plasminogen activator receptor (uPAR) and vascular endothelial growth factor (VEGF) expression with clinical and pathological characteristics of human gallbladder cancer.

METHODS: uPAR and VEGF expressions in 68 gallbladder cancer tissues were detected with anti-receptor immunohistochemical stain.

RESULTS: Expression rate of uPAR was 57.4% (39/68), and VEGF 51.5% (35/68) in gallbladder cancer tissues. Expression of both uPAR and VEGF was significantly related to metastasis, but not significantly correlated with differentiation stage and size of gallbladder cancer.

CONCLUSION: Expression of uPAR and VEGF may be an invasive phenotype of gallbladder cancer and indicator for predicting prognoses, and uPAR expression is significantly correlated with the expression of VEGF.