GDF-15: a novel serum marker for metastases in uveal melanoma patients

TRPP2 is located in the primary cilia of human non-pigmented ciliary epithelial cells

PURPOSE

Mechanosensitive channels (MSCs) and primary cilium possess a possible relevance for the sensation of intraocular pressure (IOP). However, there is only limited data on their expression and localization in the ciliary body epithelium (CBE). The purpose of this study was to characterize the expression and localization of TRPP2 in a human non-pigmented ciliary epithelial cell (HNPCE) line.

METHODS

The expression of the TRPP2 was studied by quantitative (q)RT-PCR and in situ hybridization in rat and human tissue. Protein expression and distribution were studied by western blot analysis, immunohistochemistry, and immunoelectron microscopy. Cellular location of TRPP2 was determined in rat and human CBE by immunofluorescence and immunoblot analysis. Electron microscopy studies were conducted to evaluate where and with substructure TRPP2 is localized in the HNPCE cell line.

RESULTS

The expression of TRPP2 in rat and human non-pigmented ciliary epithelium was detected. TRPP2 was mainly located in nuclei, but also showed a punctate distribution pattern in the cytoplasm of HNPCE of the tissue and the cell line. In HNPCE cell culture, primary cilia did exhibit different length following serum starvation and hydrostatic pressure. TRPP2 was found to be colocalized with these cilia in HNPCE cells.

CONCLUSION

The expression of TRPP2 and the primary cilium in the CB may indicate a possible role, such as the sensing of hydrostatic pressure, for the regulation of IOP. Functional studies via patch clamp or pharmacological intervention have yet to clarify the relevance for the physiological situation or aqueous humor regulation.

Macrophage inhibitory cytokine-1 in cancer: Beyond the cellular phenotype

Despite technological advances in diagnostic abilities and improved treatment methods, the burden of cancers remains high, leading to significant morbidity and mortality. One primary reason is that cancer cell secretory factors modulate the tumor microenvironment, supporting tumor growth and circumvents anticancer activities of conventional therapies. Macrophage inhibitory cytokine-1 (MIC-1) is a pleiotropic cytokine elevated in various cancers. MIC-1 regulates various cancer hallmarks, including sustained proliferation, tumor-promoting inflammation, avoiding immune destruction, inducing invasion, metastasis, angiogenesis, and resisting cell death. Despite these facts, the molecular regulation and downstream signaling of MIC-1 in cancer remain elusive, partly because its receptor (GFRAL) was unknown until recently. Binding of MIC-1 to GFRAL recruits the coreceptor tyrosine kinase RET to execute its downstream signaling. So far, studies have shown that GFRAL expression is restricted to the brain stem and is responsible for MIC-1/GFRAL/RET-mediated metabolic disorders. Nevertheless, abundant levels of MIC-1 expression have been reported in all cancer types and have been proposed as a surrogate biomarker. Given the ubiquitous expression of MIC-1 in cancers, it is crucial to understand both upstream regulation and downstream MIC-1/GFRAL/RET signaling in cancer hallmark traits.

Proteomics in uveal melanoma

PURPOSE OF REVIEW

This article reviews the latest proteomic research on uveal melanoma.

RECENT FINDINGS

Proteomic analysis of uveal melanoma cell lines and tissue specimens has improved our understanding of the pathophysiology of uveal melanoma and helped identify potential prognostic biomarkers. Circulating proteins in patient serum may aid in the surveillance of metastatic disease. The proteomes of aqueous and vitreous biopsy specimens may provide safer biomarkers for metastatic risk and candidate therapeutic targets in uveal melanoma. Proteomic analysis has the potential to benefit patient outcomes by improving diagnosis, prognostication, surveillance, and treatment of uveal melanoma.

SUMMARY

These recent findings demonstrate that proteomic analysis is an important area of research to better understand the pathophysiology of uveal melanoma and improve the personalized management of our patients.

Emerging Roles for Browning of White Adipose Tissue in Prostate Cancer Malignant Behaviour

In addition to its well-known role as an energy repository, adipose tissue is one of the largest endocrine organs in the organism due to its ability to synthesize and release different bioactive molecules. Two main types of adipose tissue have been described, namely white adipose tissue (WAT) with a classical energy storage function, and brown adipose tissue (BAT) with thermogenic activity. The prostate, an exocrine gland present in the reproductive system of most mammals, is surrounded by periprostatic adipose tissue (PPAT) that contributes to maintaining glandular homeostasis in conjunction with other cell types of the microenvironment. In pathological conditions such as the development and progression of prostate cancer, adipose tissue plays a key role through paracrine and endocrine signaling. In this context, the role of WAT has been thoroughly studied. However, the influence of BAT on prostate tumor development and progression is unclear and has received much less attention. This review tries to bring an update on the role of different factors released by WAT which may participate in the initiation, progression and metastasis, as well as to compile the available information on BAT to discuss and open a new field of knowledge about the possible protective role of BAT in prostate cancer.

Evaluation of a Three-Marker Panel for the Detection of Uveal Melanoma Metastases: A Single-Center Retrospective Analysis

Simple Summary

Blood-based B-cell activating factor (BAFF), growth differentiation factor-15 (GDF-15) and osteopontin (OPN) have been reported to be biomarkers for the uveal melanoma (UM) metastases. This work intended to assess their kinetics and to evaluate their significance as a three-marker panel for clinical practice. Our results not only provided their cutoff values for differentiating the metastatic patients from non-metastatic patients, but also confirmed that the three-marker panel outperformed any single biomarker in distinguishing metastatic patients. Besides, the increasing trends of the levels of three biomarkers were detected in the two-year period before the imaging diagnosis of metastases. The multiplex panel of BAFF, GDF-15 and OPN might be a utilizable implementation for the detection of UM metastases. Since it is a retrospective pilot work, more well-designed prospective studies employing larger cohorts are still needed to validate the findings.

Abstract

Blood-based B-cell activating factor (BAFF), growth differentiation factor-15 (GDF-15) and osteopontin (OPN) have been identified to be promising biomarkers for the metastases of uveal melanoma (UM). This study intended to assess their kinetics and to evaluate their significance as a three-marker panel. A group of 36 UM patients with and 137 patients without metastases were included in the study. Their plasma OPN levels were measured by ELISA; serum BAFF and GDF-15 levels were determined with a Luminex MAGPIX system. Receiver operating characteristic (ROC) analysis was performed to calculate the cutoff values of the three markers for identifying the patients with metastases. The ability to identify patients with metastases was compared between the single markers and the combination as a three-marker panel. By using the Student’s t-test, we also investigated the kinetic changes of the levels of BAFF, GDF-15 and OPN across six periods (i.e., 0–6 months, 6–12 months, 12–18 months, 18–24 months, >24 months and post-metastasis) before the imaging diagnosis of metastases. By maximizing the Youden’s index, the serum GDF-15 level of 1209 pg/mL and the plasma OPN level of 92 ng/mL were identified to have the best performance for distinguishing the metastatic patients from non-metastatic patients. The three-marker panel offered a better performance in distinguishing patients with metastases, with an area under the curve of 0.802, than any single biomarker. Increasing trends of the levels of three biomarkers were observed in the two-year period before the imaging diagnosis of metastases. The combined panel of BAFF, GDF-15 and OPN might be a utilizable implementation for the detection of UM metastases. In the bioinformatics study with two external datasets, the high expression of gene BAFF and GDF-15 in primary UM tissues was identified to be associated with poor overall survival rates. As the current work is a single-center retrospective study, more well-designed prospective investigations employing larger cohorts are urgently needed to validate our findings.

Exploring the role of BAFF as biomarker in the detection of uveal melanoma metastases

PURPOSE

While B-cell activating factor (BAFF) was identified to promote the invasion in other malignancies, its role in the progression of uveal melanoma (UM) still remains unexplored. Here, we analysed the serum level of BAFF in UM patients with regard to its significance as biomarker for the metastases.

METHODS

In this retrospective study, serum BAFF levels in 173 UM patients (36 with metastases and 137 without), and 23 healthy controls were measured with a multiplexed sandwich ELISA system and then correlated with clinicopathological characteristics such as primary tumor size, tumor location, histological cell type, sex, cancer stage, cytogenetic alterations of chromosome 3, and the metastatic burden. Immunohistochemical staining of 50 UM tissue specimens was also performed to evaluate the expression of BAFF and its receptors BAFF-R and TACI.

RESULTS

The metastatic patients were identified to have significantly higher serum BAFF levels (mean ± SD, 1520.8 ± 1182.1 pg/ml) than those without metastases (950.4 ± 494.6 pg/ml) and controls (810.3 ± 140.5 pg/ml). While no distinctions were detected with regard to tumor location, histological cell type, gender, and monosomy 3, the patients in cancer stages II, III, and IV displayed higher serum BAFF levels than those in stage I. The serum BAFF level was significantly correlated with the metastatic burden. The serum BAFF level of 1120 pg/ml was identified to have the best performance for distinguishing the metastatic patients from non-metastatic patients. In the kinetic study, we noticed that 20.8% of the analysed patients already demonstrated elevated serum BAFF concentrations before the clinical diagnosis of metastases. Positive BAFF staining was detected in the cytoplasm of single tumor cells (in 13 specimens), macrophages (in 12 specimens), and tumor-infiltrating lymphocytes (TILs) (in 13 specimens). The expressions of BAFF-R and TACI were also observed in 17 and 36 of the 50 tested UM specimens, respectively.

CONCLUSIONS

Our study first suggests that BAFF might be a promising serum marker for the detection of UM metastases.

Monosomy 3 Influences Epithelial-Mesenchymal Transition Gene Expression in Uveal Melanoma Patients; Consequences for Liquid Biopsy

Despite outstanding advances in diagnosis and the treatment of primary uveal melanoma (UM), nearly 50% of UM patients develop metastases via hematogenous dissemination, driven by the epithelial-mesenchymal transition (EMT). Despite the failure in UM to date, a liquid biopsy may offer a feasible non-invasive approach for monitoring metastatic disease progression and addressing protracted dormancy. To detect circulating tumor cells (CTCs) in UM patients, we evaluated the mRNA expression of EMT-associated transcription factors in CD45-depleted blood fraction, using qRT-PCR. ddPCR was employed to assess UM-specific GNA11, GNAQ, PLCβ4, and CYSLTR2 mutations in plasma DNA. Moreover, microarray analysis was performed on total RNA isolated from tumor tissues to estimate the prognostic value of EMT-associated gene expression. In total, 42 primary UM and 11 metastatic patients were enrolled. All CD45-depleted samples were negative for CTC when compared to the peripheral blood fraction of 60 healthy controls. Tumor-specific mutations were detected in the plasma of 21.4% patients, merely, in 9.4% of primary UM, while 54.5% in metastatic patients. Unsupervised hierarchical clustering of differentially expressed EMT genes showed significant differences between monosomy 3 and disomy 3 tumors. Newly identified genes can serve as non-invasive prognostic biomarkers that can support therapeutic decisions.

Update on uveal melanoma: Translational research from biology to clinical practice (Review)

Uveal melanoma is the most common type of intraocular cancer with a low mean annual incidence of 5‑10 cases per million. Tumours are located in the choroid (90%), ciliary body (6%) or iris (4%) and of 85% are primary tumours. As in cutaneous melanoma, tumours arise in melanocytes; however, the characteristics of uveal melanoma differ, accounting for 3‑5% of melanocytic cancers. Among the numerous risk factors are age, sex, genetic and phenotypic predisposition, the work environment and dermatological conditions. Management is usually multidisciplinary, including several specialists such as ophthalmologists, oncologists and maxillofacial surgeons, who participate in the diagnosis, treatment and complex follow‑up of these patients, without excluding the management of the immense emotional burden. Clinically, uveal melanoma generates symptoms that depend as much on the affected ocular globe site as on the tumour size. The anatomopathological study of uveal melanoma has recently benefited from developments in molecular biology. In effect, disease classification or staging according to molecular profile is proving useful for the assessment of this type of tumour. Further, the improved knowledge of tumour biology is giving rise to a more targeted approach to diagnosis, prognosis and treatment development; for example, epigenetics driven by microRNAs as a target for disease control. In the present study, the main epidemiological, clinical, physiopathological and molecular features of this disease are reviewed, and the associations among all these factors are discussed.

GDF-15 Neutralization Alleviates Platinum-Based Chemotherapy-Induced Emesis, Anorexia, and Weight Loss in Mice and Nonhuman Primates

Platinum-based cancer therapy is restricted by dose-limiting side effects and is associated with elevation of growth differentiation factor 15 (GDF-15). But whether this elevation contributes to such side effects has been unclear. Here, we explored the effects of GDF-15 blockade on platinum-based chemotherapy-induced emesis, anorexia, and weight loss in mice and/or nonhuman primate models. We found that circulating GDF-15 is higher in subjects with cancer receiving platinum-based chemotherapy and is positively associated with weight loss in colorectal cancer (NCT00609622). Further, chemotherapy agents associated with high clinical emetic score induce circulating GDF-15 and weight loss in mice. Platinum-based treatment-induced anorexia and weight loss are attenuated in GDF-15 knockout mice, while GDF-15 neutralization with the monoclonal antibody mAB1 improves survival. In nonhuman primates, mAB1 treatment attenuates anorexia and emesis. These results suggest that GDF-15 neutralization is a potential therapeutic approach to alleviate chemotherapy-induced side effects and improve the quality of life.

Upregulated GDF-15 expression facilitates pancreatic ductal adenocarcinoma progression through orphan receptor GFRAL

Growth and differentiation factor 15 (GDF-15) has been studied as an important hallmark of cancer. However, the receptor of GDF-15 in pancreatic cancer cell remains unclear. Here, we investigated its biological effects in pancreatic ductal adenocarcinoma (PDAC). We found that aberrant GDF-15 expression positively correlated with poor survival of PDAC patients. GDF-15 protein enhanced tumor cell proliferation in two pancreatic cancer lines, AsPC-1 and BxPC-3. Knockdown GDF-15 attenuated its biological function in vitro and reduced PDAC cell tumorigenesis upon xenotransplantation into nude mice. Moreover, we identified that glial-derived neurotropic factor family receptor α-like (GFRAL) was upregulated in PDAC tissues and positively correlated with GDF-15 expression. High GFRAL expression was significantly associated with poor survival in PDAC patients. Furthermore, we identified that the biological effects of GDF-15 are mediated by its receptor GFRAL which is present in PDAC cells. After overexpression GFRAL in pancreatic cancer cells, the effect of GDF-15 was significantly enhanced. Overall, our findings demonstrated that the GDF-15 secreted by PDAC cells, binds to GFRAL, itself localized in PDAC cells, to promote cancer cell growth and metastasis through the GDF-15/GFRAL signaling pathway.

Growth differentiation factor 15 (GDF15) in cancer cell metastasis: from the cells to the patients

Growth differentiation factor 15 (GDF15), a member of the transforming growth factor β superfamily, has been postulated to be implicated in cancer cell metastasis although its role has not been fully elucidated yet. The purpose of this review is to clarify the role of GDF-15 in cancer cell metastasis based on current advances in the field. The studies were divided into those involving evaluation of GDF15 expression in the serum or tissue of cancer patients, and those involving in vitro experiments in cancer cell lines or in vivo experiments in animal models. GDF15 was shown to be elevated in the serum or tissues of cancer patients with its expression being correlated with decreased survival. Moreover, most in vitro and in vivo studies also corroborated a metastasis-promoting role for GDF15. However, there were a few studies, where GDF15 was shown to suppress the metastatic properties of cells. As, GDF15 has been known for its pleiotropic effects, it is not surprising to behave differently in different types of cancer. Thus, GDF15 has the potential of not only being a useful metastasis biomarker, but also a promising therapeutic target against cancer cell metastasis in many cancer types.

Growth/Differentiation Factor-15 (GDF-15): From Biomarker to Novel Targetable Immune Checkpoint

Growth/differentiation factor-15 (GDF-15), also named macrophage inhibitory cytokine-1, is a divergent member of the transforming growth factor β superfamily. While physiological expression is barely detectable in most somatic tissues in humans, GDF-15 is abundant in placenta. Elsewhere, GDF-15 is often induced under stress conditions, seemingly to maintain cell and tissue homeostasis; however, a moderate increase in GDF-15 blood levels is observed with age. Highly elevated GDF-15 levels are mostly linked to pathological conditions including inflammation, myocardial ischemia, and notably cancer. GDF-15 has thus been widely explored as a biomarker for disease prognosis. Mechanistically, induction of anorexia via the brainstem-restricted GDF-15 receptor GFRAL (glial cell-derived neurotrophic factor [GDNF] family receptor α-like) is well-documented. GDF-15 and GFRAL have thus become attractive targets for metabolic intervention. Still, several GDF-15 mediated effects (including its physiological role in pregnancy) are difficult to explain via the described pathway. Hence, there is a clear need to better understand non-metabolic effects of GDF-15. With particular emphasis on its immunomodulatory potential this review discusses the roles of GDF-15 in pregnancy and in pathological conditions including myocardial infarction, autoimmune disease, and specifically cancer. Importantly, the strong predictive value of GDF-15 as biomarker may plausibly be linked to its immune-regulatory function. The described associations and mechanistic data support the hypothesis that GDF-15 acts as immune checkpoint and is thus an emerging target for cancer immunotherapy.

Blood Biomarkers of Uveal Melanoma: Current Perspectives

The detection of metastases in patients with a diagnosis of uveal melanoma (UM) is a controversial issue. While only 1% of the patients have detectable metastases at the time of diagnosis, up to 30% of them will develop liver metastases within 5 years of treatment. UM spreads hematogenously, therefore, blood biomarkers may be helpful for prognosis and monitoring the disease progression. Despite the great progress achieved thanks to the genetic analysis of UM biopsies, this is an invasive technique and is limited by the heterogeneity of the tumor. The present review considers the current understanding in the field regarding biomarkers for the diagnosis and prognosis of UM and its metastasis, primarily to the liver. General covered topics include non-conventional markers such as proteins previously identified in cutaneous melanoma and UM cell lines, circulating tumor cells, microRNAs (miRNA), and circulating DNA, and how each may be critical in the development of novel blood biomarkers for UM.

GDF15 promotes osteosarcoma cell migration and invasion by regulating the TGF‑β signaling pathway

Growth and differentiation factor 15 (GDF15), a novel divergent member of the transforming growth factor‑β (TGF‑β) superfamily, was previously reported to be overexpressed in various types of cancers and was shown to be involved in tumor metastasis; however, the role of GDF15 in the development and malignant progression of osteosarcoma remains unclear. In the present study, reverse transcription‑quantitative polymerase chain reaction, western blot and ELISA analyses were performed to detect mRNA and protein expression, including that of GDF15, SMAD2 and SMAD3. Wound‑healing and cell invasion assays were conducted to determine the migratory and invasive abilities of osteosarcoma cells. A luciferase assay was performed to evaluate the transcriptional activity of a TGF‑β/SMAD‑responsive luciferase reporter. The Kaplan‑Meier method was used to generate survival curves, with a log‑rank test use to evaluate differences in survival. The results revealed that GDF15 expression was upregulated in metastatic osteosarcoma tissues compared with non‑metastatic osteosarcoma tissues. Patients with osteosarcoma that possessed high serum GDF15 levels exhibited significantly decreased overall survival (OS) and pulmonary metastasis‑free survival (PMFS) time compared with patients with low GDF15 expression. Furthermore, high serum GDF15 was an independent prognostic parameter for poor OS and short PMFS. Additionally, it was observed that the knockdown of GDF15 attenuated the migration and invasion of osteosarcoma cells. Silencing GDF15 markedly suppressed the TGF‑β signaling pathway. In conclusion, GDF15 may promote osteosarcoma cell metastasis by regulating the TGF‑β signaling pathway, and serum GDF15 levels may be a potential prognostic and pulmonary metastasis‑predictive biomarker in osteosarcoma.

Growth differentiation factor 15 and its role in carcinogenesis: an update

Growth differentiation factor-15 (GDF-15) is a novel cytokine secreted by a variety of cells like macrophages, adipocytes, normally expressed in high amounts by placenta. It is also highly expressed in multiple carcinomas like Colon, Breast, Pancreas, Liver, and Ovarian. Several reports on serum GDF-15 as a potential biomarker for diagnosis and prognosis of cancer are hampered by the lack of robust data, with large sample size and critical patient recruitment. However, experimental accounts on cancer tumors, cell lines, and animal models suggest GDF-15's role in cancer progression via endothelial mesenchymal transition, angiogenesis, metastasis, drug resistance and even stemness of various cancers. GDF-15 could be the point of amalgamation for the various hallmarks of cancer and can prove a useful therapeutic target in cancer. The current review was conceptualized with a thought of critically appraising the existing information of GDF-15 in carcinogenesis.

A multiplex immunoassay of serum biomarkers for the detection of uveal melanoma

Background

Approximately 50% of uveal melanoma (UM) patients develop metastases preferentially in the liver leading to death within 15 months. Currently, there is no effective treatment for metastatic UM, in part because the tumor burden is typically high when liver metastases are detected through abnormal liver function tests (LFTs) or imaging studies. The use of LFTs results followed by diagnostic tests has high specificity and predictive values but low sensitivity, and better tests are needed for early diagnosis of the primary tumor as well as its metastatic spread. To evaluate serum biomarkers for the early detection of UM, multiplex immunoassays were developed.

Methods

Magnetic bead-based multiplex immunoassays were developed for the selected serum biomarkers using a Bio-Plex 200 system. The dynamic ranges, lower limits of detection and quantification, cross-reactivity, and intra- and inter-assay precision were assessed. All proteins were analyzed in sera of 48 patients diagnosed with UM (14 metastatic, 9 disease–free (DF) ≥ 5 years, 25 unknown) and 36 healthy controls. The performance of the biomarkers was evaluated individually and in combination for their ability to detect UM.

Results

A 7-plex immunoassay of OPN, MIA, CEACAM-1, MIC-1, SPON1, POSTN and HSP27 was developed with negligible cross-reactivity, recovery of 84–105%, and intra-assay and inter-assay precision of 2.3–7.5% or 2.8–20.8%, respectively. Logistic regression identified a two-marker panel of HSP27 and OPN that significantly improved the individual biomarker performance in discriminating UM from healthy controls. The improved discrimination of a two-marker panel of MIA and MIC-1 was also observed between metastatic UM and DF, however not statistically significant due to the small sample size.

Conclusions

The multiplex immunoassay provides sufficient analytical performance to evaluate serum biomarkers that complement each other in detection of UM, and warrants further validation with a larger number of patient samples.

Electronic supplementary material

The online version of this article (10.1186/s12014-019-9230-8) contains supplementary material, which is available to authorized users.

Inhibition of Breast Cancer Cell Invasion by Ras Suppressor-1 (RSU-1) Silencing Is Reversed by Growth Differentiation Factor-15 (GDF-15)

Extracellular matrix (ECM)-related adhesion proteins are important in metastasis. Ras suppressor-1 (RSU-1), a suppressor of Ras-transformation, is localized to cell–ECM adhesions where it interacts with the Particularly Interesting New Cysteine-Histidine rich protein (PINCH-1), being connected to Integrin Linked Kinase (ILK) and alpha-parvin (PARVA), a direct actin-binding protein. RSU-1 was also found upregulated in metastatic breast cancer (BC) samples and was recently demonstrated to have metastasis-promoting properties. In the present study, we transiently silenced RSU-1 in BC cells, MCF-7 and MDA-MB-231. We found that RSU-1 silencing leads to downregulation of Growth Differentiation Factor-15 (GDF-15), which has been associated with both actin cytoskeleton reorganization and metastasis. RSU-1 silencing also reduced the mRNA expression of PINCH-1 and cell division control protein-42 (Cdc42), while increasing that of ILK and Rac regardless of the presence of GDF-15. However, the downregulation of actin-modulating genes PARVA, RhoA, Rho associated kinase-1 (ROCK-1), and Fascin-1 following RSU-1 depletion was completely reversed by GDF-15 treatment in both cell lines. Moreover, complete rescue of the inhibitory effect of RSU-1 silencing on cell invasion was achieved by GDF-15 treatment, which also correlated with matrix metalloproteinase-2 expression. Finally, using a graph clustering approach, we corroborated our findings. This is the first study providing evidence of a functional association between RSU-1 and GDF-15 with regard to cancer cell invasion.

Nestin expression in primary and metastatic uveal melanoma - possible biomarker for high-risk uveal melanoma

PURPOSE

Nestin, a member of the intermediate filament protein family, has been described as a putative cancer stem cell marker (CSC) in uveal melanoma and poor prognostic factor in a variety of tumours, including cutaneous melanoma. In this study, we examined the expression of nestin in primary (PUM) and metastatic uveal melanoma (MUM) samples, and correlated the findings with histological, clinical and survival data.

METHODS

Nestin expression was assessed by immunohistochemistry in 141 PUM and 26 MUM samples; 11 PUM cases were matched with their corresponding metastases. The percentage of tumour cells expressing nestin was scored by three independent observers. Statistical analysis of all data was performed with SPSS.

RESULTS

Nestin expression was identified in both the cytoplasm and membrane of UM cells. Increased expression of nestin in PUM samples was associated with known poor prognostic parameters, including epithelioid cell morphology (p < 0.001), closed loops (p = 0.001), higher mitotic count (p < 0.001), monosomy 3 (p = 0.007) and chromosome 8q gain (p < 0.001). Primary uveal melanoma (PUM) with nestin expression levels above a cut-off value of 10% [as determined by receiver operating characteristic (ROC) analysis] was associated with a significantly reduced survival time (Log-rank, p = 0.002). In MUM, a higher percentage of nestin-positive tumour cells combined with poor prognostic markers in the PUM led to a shorter survival time following the development of metastases.

CONCLUSION

In conclusion, increased nestin expression in PUM is a predictor of a tumour phenotype associated with metastatic progression and reduced survival time at onset of metastasis.

In-depth proteomic profiling of the uveal melanoma secretome

Uveal melanoma (UM), the most common primary intraocular tumour in adults, is characterised by a high frequency of metastases to the liver, typically with a fatal outcome. Proteins secreted from cancer cells (‘secretome’) are biologically important molecules thought to contribute to tumour progression. We examined the UM secretome by applying a label-free nanoLCMS/MS proteomic approach to profile proteins secreted into culture media by primary UM tumours with a high− (HR; n = 11) or low− (LR; n = 4) metastatic risk, compared to normal choroidal melanocytes (NCM) from unaffected post-mortem eyes. Across the three groups, 1843 proteins were identified at a 1% false discovery rate; 758 of these by at least 3 unique peptides, and quantified. The majority (539/758, 71%) of proteins were classified as secreted either by classical (144, 19%), non-classical (43, 6%) or exosomal (352, 46%) mechanisms. Bioinformatic analyzes showed that the secretome composition reflects biological differences and similarities of the samples. Ingenuity^® pathway analysis of the secreted protein dataset identified abundant proteins involved in cell proliferation-, growth- and movement. Hepatic fibrosis/hepatic stellate cell activation and the mTORC1-S6K signalling axis were among the most differentially regulated biological processes in UM as compared with NCM. Further analysis of proteins upregulated ≥ 2 in HR-UM only, identified exosomal proteins involved in extracellular matrix remodelling and cancer cell migration/invasion; as well as classically secreted proteins, possibly representing novel biomarkers of metastatic disease. In conclusion, UM secretome analysis identifies novel proteins and pathways that may contribute to metastatic development at distant sites, particularly in the liver.

An Assessment of Novel Biomarkers in Bone Metastatic Disease Using Multiplex Measurement and Multivariate Analysis

Aim:

Current diagnostics of bone metastatic disease is not satisfactory for early detection or regular process monitoring. The combination of biomarkers and the multiparametric approach was described as effective in other oncology diagnoses. The aim of the study was to improve the difference diagnostics between bone-metastatic disease and solid tumors using mutivariate logistic regression model.

Methods:

We assessed the group of 131 patients with the following diagnoses: prostate cancer, breast cancer, lung cancer, and colorectal cancer. According to the results of scintigraphy, the cohort was divided into 2 groups based on the occurrence of bone metastases. Group 0 was a control group of 75 patients with no signs of bone metastases and group 1 included 56 patients with bone metastases.

Results:

We used stepwise selection multivariate logistic regression for choosing the multimarker formula for calculation of risk score for bone metastases diagnostics. For detection of bone metastasis, it was shown to be most effective measurement of 3 biomarkers: procollagen type 1 N-terminal propeptide, growth differentiation factor-15, and osteonectin and combining with calculation of risk score by designating measured concentrations in mathematical formula: bone risk score = procollagen type 1 N-terminal propeptide × 0.0500 + growth differentiation factor-15 × 1.4179 + osteonectin × 0.00555.

Conclusion:

We identified growth differentiation factor-15 as the best individual marker for bone metastasis diagnostics. The best formula for risk score includes levels of 3 biomarkers—procollagen type 1 N-terminal propeptide, growth differentiation factor-15, and osteonectin. The new score has better performance described by higher area under the curve than individual biomarkers. A further study is necessary to confirm these findings incorporating a larger number of patients.

The biology of uveal melanoma

Uveal melanoma (UM), a rare cancer of the eye, is distinct from cutaneous melanoma by its etiology, the mutation frequency and profile, and its clinical behavior including resistance to targeted therapy and immune checkpoint blockers. Primary disease is efficiently controlled by surgery or radiation therapy, but about half of UMs develop distant metastasis mostly to the liver. Survival of patients with metastasis is below 1 year and has not improved in decades. Recent years have brought a deep understanding of UM biology characterized by initiating mutations in the G proteins GNAQ and GNA11. Cytogenetic alterations, in particular monosomy of chromosome 3 and amplification of the long arm of chromosome 8, and mutation of the BRCA1-associated protein 1, BAP1, a tumor suppressor gene, or the splicing factor SF3B1 determine UM metastasis. Cytogenetic and molecular profiling allow for a very precise prognostication that is still not matched by efficacious adjuvant therapies. G protein signaling has been shown to activate the YAP/TAZ pathway independent of HIPPO, and conventional signaling via the mitogen-activated kinase pathway probably also contributes to UM development and progression. Several lines of evidence indicate that inflammation and macrophages play a pro-tumor role in UM and in its hepatic metastases. UM cells benefit from the immune privilege in the eye and may adopt several mechanisms involved in this privilege for tumor escape that act even after leaving the niche. Here, we review the current knowledge of the biology of UM and discuss recent approaches to UM treatment.

High GDF-15 Serum Levels Independently Correlate with Poorer Overall Survival of Patients with Tumor-Free Stage III and Unresectable Stage IV Melanoma

Biomarkers are strongly needed for diagnostic surveillance of patients with metastatic melanoma. On the basis of its known association with tumor metastasis and its ability to induce cancer cachexia, we investigated serum levels of growth and differentiation factor 15 (sGDF-15) as a marker for overall survival (OS). sGDF-15 was retrospectively measured by ELISA in 761 samples obtained at distinct time points during routine clinical care of patients with stage III/IV melanoma. In the entire cohort, sGDF-15 ≥ 1.5 ng/ml was strongly associated with reduced OS after assessment. Subsequent analyses were performed separately for tumor-free stage III, tumor-free stage IV, and unresectable stage IV patients. For patients with unresectable distant metastasis (n = 206), sGDF-15 was independently associated with OS when considered together with the M-category and superior to serum level of lactate dehydrogenase. Analysis in tumor-free stage III patients during routine surveillance (n = 468) revealed sGDF-15 to be associated with OS and an independent factor when considered together with S100B and the pattern of locoregional metastasis. Only in tumor-free stage IV patients (n = 87) sGDF-15 was not associated with OS. sGDF-15 should thus be further validated as a marker for early detection of recurrence in stage III patients and as a prognostic or predictive marker particularly in the context newly available treatments in unresectable stage IV patients.

The divergent roles of growth differentiation factor-15 (GDF-15) in benign and malignant skin pathologies

GDF-15 (Growth Differentiation Factor-15) is a member of the transforming growth factor β (TGF-β) superfamily. GDF-15 is not only involved in cancer development, progression, angiogenesis and metastasis, but also controls stress responses, bone formation, hematopoietic development, adipose tissue function and cardiovascular diseases. GDF-15, which is regulated by p53, has shown antitumorigenic and proapoptotic activities in vivo and in vitro. Also, GDF-15 is involved in skin biology and histamine-induced melanogenesis; it is overexpressed in melanoma cells and is associated with depth of tumor invasion and metastasis. GDF-15 level is increased in patients with systemic sclerosis and is related with the degree of skin sclerosis and intensity of pulmonary fibrosis. In the future, GDF-15 may be a potential target for therapy in benign disorders with skin fibrosis and malignant lesions of the skin.

Growth Differentiation Factor-15 (GDF-15) is a potential marker of radiation response and radiation sensitivity

We have investigated the importance of GDF-15 (secreted cytokine belonging to the TGF-β superfamily) in low and high dose radiation-induced cellular responses. A telomerase immortalized human fibroblast cell line (F11hT) was used in the experiments. A lentiviral system encoding small hairpin RNAs (shRNA) was used to establish GDF-15 silenced cells. Secreted GDF-15 levels were measured in culture medium by ELISA. Cell cycle analysis was performed by flow cytometry. The experiments demonstrated that in irradiated human fibroblasts GDF-15 expression increased with dose starting from 100mGy. Elevated GDF-15 expression was not detected in bystander cells. The potential role of GDF-15 in radiation response was investigated by silencing GDF-15 in immortalized human fibroblasts with five different shRNA encoded in lentiviral vectors. Cell lines with considerably reduced GDF-15 levels presented increased radiation sensitivity, while a cell line with elevated GDF-15 was more radiation resistant than wild type cells. We have investigated how the reduced GDF-15 levels alter the response of several known radiation inducible genes. In F11hT-shGDF-15 cells the basal expression level of CDKN1A was unaltered relative to F11hT cells, while GADD45A and TGF-β1 mRNA levels were slightly higher, and TP53INP1 was considerably reduced. The radiation-induced expression of TP53INP1 was lower in the silenced than in wild type fibroblast cells. Cell cycle analysis indicated that radiation-induced early G2/M arrest was abrogated in GDF-15 silenced cells. Moreover, radiation-induced bystander effect was less pronounced in GDF-15 silenced fibroblasts. In conclusion, the results suggest that GDF-15 works as a radiation inducible radiation resistance increasing factor in normal human fibroblast cells, acts by regulating the radiation-induced transcription of several genes and might serve as a radiation-induced early biomarker in exposed cells.

Association of serum level of growth differentiation factor 15 with liver cirrhosis and hepatocellular carcinoma

Hepatocellular carcinoma (HCC) and liver cirrhosis are associated with high mortality worldwide. Currently, alpha-fetoprotein (AFP) is used as a standard serum marker for the detection of HCC, but its sensitivity and specificity are unsatisfactory, and optimal diagnostic markers for cirrhosis are lacking. We previously reported that growth differentiation factor 15 (GDF15) was significantly induced in HCV-infected hepatocytes. This study aimed to investigate GDF15 expression and its correlation with hepatitis virus-related liver diseases. A total of 412 patients with various liver diseases were studied. Healthy and Mycobacterium tuberculosis-infected subjects were included as controls. Serum and tissue GDF15 levels were measured. Serum GDF15 levels were significantly increased in patients with HCC (6.66±0.67 ng/mL, p<0.0001) and cirrhosis (6.51±1.47 ng/mL, p<0.0001) compared with healthy controls (0.31±0.01 ng/mL), though the GDF15 levels in HBV and HCV carriers were moderately elevated (1.34±0.19 ng/mL and 2.13±0.53 ng/mL, respectively). Compared with HBV or HCV carriers, GDF15 had a sensitivity of 63.1% and a specificity of 86.6% at the optimal cut-off point of 2.463 ng/mL in patients with liver cirrhosis or HCC. In HCC patients, the area under the receiver operating curve was 0.84 for GDF15 and 0.76 for AFP, but 0.91 for the combined GDF15 and AFP. Serum GDF15 levels did not significantly differ between the high-AFP and low-AFP groups. GDF15 protein expression in HCC was significantly higher than that in the corresponding adjacent paracarcinomatous tissue and normal liver. Using a combination of GDF15 and AFP will improve the sensitivity and specificity of HCC diagnosis. Further research and the clinical implementation of serum GDF15 measurement as a biomarker for HCC and cirrhosis are recommended.

Macrophage inhibitory cytokine-1 (MIC-1/GDF15) gene deletion promotes cancer growth in TRAMP prostate cancer prone mice

The divergent TGF-β superfamily member, macrophage inhibitory cytokine-1 (MIC-1/GDF15), is overexpressed by most cancers, including prostate cancer (PCa). Whilst its circulating levels are linked to cancer outcome, the role MIC-1/GDF15 plays in cancer development and progression is incompletely understood. To investigate its effect on PCa development and spread, we have used TRAMP prostate cancer prone mice bearing a germline deletion of MIC-1/GDF15 (TRAMPMIC-/-). On average TRAMPMIC-/- mice died about 5 weeks earlier and had larger prostatic tumors compared with TRAMP mice that were wild type for MIC-1/GDF15 (TRAMPMIC+/+). Additionally, at the time of death or ethical end point, even when adjusted for lifespan, there were no significant differences in the number of mice with metastases between the TRAMPMIC+/+ and TRAMPMIC-/- groups. However, consistent with our previous data, more than twice as many TRAMP mice overexpressing MIC-1/GDF15 (TRAMPfmsmic-1) had metastases than TRAMPMIC+/+ mice (p<0.0001). We conclude that germ line gene deletion of MIC-1/GDF15 leads to increased local tumor growth resulting in decreased survival consistent with an overall protective role for MIC-1/GDF15 in early primary tumor development. However, in advancing disease, as we have previously noted, MIC-1/GDF15 overexpression may promote local invasion and metastatic spread.

Role of GDF15 in radiosensitivity of breast cancer cells

The Growth Differentiation Factor-15 gene (GDF15) is a member of TGF-b superfamily and this cytokine family is considered to be a promising target for cancer therapy. The purpose of this study was to investigate the effect of tumor derived GDF15 on proliferation and radiosensitivity of breast cancer cells in vitro and in vivo. A mouse breast cancer LM2 cell line with stable transfection of full-length mouse GDF15 cDNA was established. Cell growth and proliferation was observed using WST assay and impedance-based method. Radiation induced GDF15 and TGF-b1 expression was determined by qRT-PCR. Radiosensitivity was measured by a colony formation assay in vitro and by a tumor growth delay assay in vivo. Cells with more than a 10-fold increase in GDF15 expression had a higher growth rate than parental control cells in vitro and in vivo. The radiation induced elevation of the expression of TGFb1 was reduced in GDF15 overexpressing cells. GDF15 may play a role in the radiation response of breast cancer cells by effecting cell survival, inhibiting radiation-induced cell death, and inhibiting the TGF-b1 related cytotoxic action.

Growth differentiation factor-15 suppresses maturation and function of dendritic cells and inhibits tumor-specific immune response

Dendritic cells (DCs) play a key role in the initiation stage of an antigen-specific immune response. A variety of tumor-derived factors (TDFs) can suppress DC maturation and function, resulting in defects in the tumor-specific immune response. To identify unknown TDFs that may suppress DCs maturation and function, we established a high-throughput screening technology based on a human liver tumor T7 phage cDNA library and screened all of the proteins derived from hepatoma cells that potentially interact with immature DCs. Growth/differentiation factor-15 (GDF-15) was detected and chosen for further study. By incubation of DCs cultures with GDF-15, we demonstrate that GDF-15 can inhibit surface protrusion formation during DC maturation; suppress the membrane expression of CD83, CD86 and HLA-DR on DCs; enhance phagocytosis by DCs; reduce IL-12 and elevate TGF-β1 secretion by DCs; inhibit T cell stimulation and cytotoxic T lymphocyte (CTL) activation by DCs. By building tumor-bearing mouse models, we demonstrate that GDF-15 can inhibit the ability of DCs to stimulate a tumor-specific immune response in vivo. These results indicate that GDF-15 may be one of the critical molecules that inhibit DC maturation and function and are involved in tumor immune escape. Thus, GDF-15 may be a novel target in tumor immunotherapy.

Histamine receptor 2-mediated growth-differentiation factor-15 expression is involved in histamine-induced melanogenesis

Vitiligo is a progressive depigmenting disorder. Histamine has been shown to induce melanogenesis via histamine receptor 2, suggesting the possibility of histamine as a repigmenting agent for the treatment of vitiligo. However, the role and signaling mechanism of histamine are still unclear in melanogenesis, especially in relation to growth-differentiation factor-15, which is a protein belonging to transforming growth factor beta and found to be overexpressed in metastatic or malignant melanoma. We found that histamine induces growth-differentiation factor-15 in melanoma cell lines such as SK-MEL-2, B16F10, and melan-a cells. Therefore, in the present study, the role of growth-differentiation factor-15 in histamine-induced melanogenesis was investigated using gene silencing or overexpression of growth-differentiation factor-15 and histamine related compounds such as histamine, amthamine, and cimetidine. Gene silencing of growth-differentiation factor-15 suppressed histamine-induced proliferation, melanin production, tyrosinase activity, and chemotactic migration of SK-MEL-2 cells. Histamine-induced expression of tyrosinase, tyrosinase-related protein 1, and tyrosinase-related protein 2 was also suppressed by growth-differentiation factor-15 gene silencing. On the other hand, overexpression of growth-differentiation factor-15 using a plasmid containing growth-differentiation factor-15 in SK-MEL-2 cells increased melanin production and chemotactic migration. Amthamine induced expression of growth-differentiation factor-15 in a time and concentration dependent manner. Amthamine-induced expression of growth-differentiation factor-15 was suppressed by cimetidine. Our results suggest that growth-differentiation factor-15 is a new player in histamine-induced melanogenesis, which can help researchers to extend the knowledge of the role of the transforming growth factor beta family in melanogenesis and in skin pigment disorders such as vitiligo.

Macrophage inhibitory cytokine-1 (MIC-1/GDF15) slows cancer development but increases metastases in TRAMP prostate cancer prone mice

Macrophage inhibitory cytokine-1 (MIC-1/GDF15), a divergent member of the TGF-β superfamily, is over-expressed by many common cancers including those of the prostate (PCa) and its expression is linked to cancer outcome. We have evaluated the effect of MIC-1/GDF15 overexpression on PCa development and spread in the TRAMP transgenic model of spontaneous prostate cancer. TRAMP mice were crossed with MIC-1/GDF15 overexpressing mice (MIC-1(fms)) to produce syngeneic TRAMP(fmsmic-1) mice. Survival rate, prostate tumor size, histopathological grades and extent of distant organ metastases were compared. Metastasis of TC1-T5, an androgen independent TRAMP cell line that lacks MIC-1/GDF15 expression, was compared by injecting intravenously into MIC-1(fms) and syngeneic C57BL/6 mice. Whilst TRAMP(fmsmic-1) survived on average 7.4 weeks longer, had significantly smaller genitourinary (GU) tumors and lower PCa histopathological grades than TRAMP mice, more of these mice developed distant organ metastases. Additionally, a higher number of TC1-T5 lung tumor colonies were observed in MIC-1(fms) mice than syngeneic WT C57BL/6 mice. Our studies strongly suggest that MIC-1/GDF15 has complex actions on tumor behavior: it limits local tumor growth but may with advancing disease, promote metastases. As MIC-1/GDF15 is induced by all cancer treatments and metastasis is the major cause of cancer treatment failure and cancer deaths, these results, if applicable to humans, may have a direct impact on patient care.