Midkine: an emerging target of drug development for treatment of multiple diseases

GPC2 promotes prostate cancer progression via MDK-mediated activation of PI3K/AKT signaling pathway

Prostate cancer is a major medical problem for men worldwide. Advanced prostate cancer is currently incurable. Recently, much attention was paid to the role of GPC2 in the field of oncology. Nevertheless, there have been no investigations of GPC2 and its regulatory mechanism in prostate cancer. Here, we revealed a novel action of GPC2 and a tumor promoting mechanism in prostate cancer. GPC2 was upregulated in prostate cancer tissues and cell lines. Higher expression of GPC2 was correlated with higher Gleason score, lymphatic metastasis, and worse overall survival in prostate cancer patients. Decreased expression of GPC2 inhibited cell proliferation, migration, and invasion in prostate cancer, whereas GPC2 overexpression promoted these properties. Mechanistically, GPC2 promoted the activation of PI3K/AKT signaling pathway through MDK. The rescue assay results in prostate cancer cells demonstrated that overexpression of MDK could attenuate GPC2 knockdown induced inactivation of PI3K/AKT signaling and partly reverse GPC2 knockdown induced inhibition of cell proliferation, migration, and invasion. In all, our study identified GPC2 as an oncogene in prostate cancer. GPC2 promoted prostate cancer cell proliferation, migration, and invasion via MDK-mediated activation of PI3K/AKT signaling pathway. GPC2 might be a promising prognosis predictor and potential therapeutic target in prostate cancer.

The novel role of lymphatic vessels in the pathogenesis of ocular diseases

Historically, the eye has been considered as an organ free of lymphatic vessels. In recent years, however, it became evident, that lymphatic vessels or lymphatic-like vessels contribute to several ocular pathologies at various peri- and intraocular locations. The aim of this review is to outline the pathogenetic role of ocular lymphatics, the respective molecular mechanisms and to discuss current and future therapeutic options based thereon. We will give an overview on the vascular anatomy of the healthy ocular surface and the molecular mechanisms contributing to corneal (lymph)angiogenic privilege. In addition, we present (i) current insights into the cellular and molecular mechanisms occurring during pathological neovascularization of the cornea triggered e.g. by inflammation or trauma, (ii) the role of lymphatic vessels in different ocular surface pathologies such as dry eye disease, corneal graft rejection, ocular graft versus host disease, allergy, and pterygium, (iii) the involvement of lymphatic vessels in ocular tumors and metastasis, and (iv) the novel role of the lymphatic-like structure of Schlemm's canal in glaucoma. Identification of the underlying molecular mechanisms and of novel modulators of lymphangiogenesis will contribute to the development of new therapeutic targets for the treatment of ocular diseases associated with pathological lymphangiogenesis in the future. The preclinical data presented here outline novel therapeutic concepts for promoting transplant survival, inhibiting metastasis of ocular tumors, reducing inflammation of the ocular surface, and treating glaucoma. Initial data from clinical trials suggest first success of novel treatment strategies to promote transplant survival based on pretransplant corneal lymphangioregression.

Schwann cells regulate tumor cells and cancer-associated fibroblasts in the pancreatic ductal adenocarcinoma microenvironment

Neuropathy is a feature more frequently observed in pancreatic ductal adenocarcinoma (PDAC) than other tumors. Schwann cells, the most prevalent cell type in peripheral nerves, migrate toward tumor cells and associate with poor prognosis in PDAC. To unveil the effects of Schwann cells on the neuro-stroma niche, here we perform single-cell RNA-sequencing and microarray-based spatial transcriptome analysis of PDAC tissues. Results suggest that Schwann cells may drive tumor cells and cancer-associated fibroblasts (CAFs) to more malignant subtypes: basal-like and inflammatory CAFs (iCAFs), respectively. Moreover, in vitro and in vivo assays demonstrate that Schwann cells enhance the proliferation and migration of PDAC cells via Midkine signaling and promote the switch of CAFs to iCAFs via interleukin-1α. Culture of tumor cells and CAFs with Schwann cells conditioned medium accelerates PDAC progression. Thus, we reveal that Schwann cells induce malignant subtypes of tumor cells and CAFs in the PDAC milieu.

Role of Midkine in Cancer Drug Resistance: Regulators of Its Expression and Its Molecular Targeting

Molecules involved in drug resistance can be targeted for better therapeutic efficacies. Research on midkine (MDK) has escalated in the last few decades, which affirms a positive correlation between disease progression and MDK expression in most cancers and indicates its association with multi-drug resistance in cancer. MDK, a secretory cytokine found in blood, can be exploited as a potent biomarker for the non-invasive detection of drug resistance expressed in various cancers and, thereby, can be targeted. We summarize the current information on the involvement of MDK in drug resistance, and transcriptional regulators of its expression and highlight its potential as a cancer therapeutic target.

Mechano-cytoskeleton remodeling mechanism and molecular docking studies on nanosurface technology: Titania nanotube arrays

In biomedical implant technology, nanosurface such as titania nanotube arrays (TNA) could provide better cellular adaptation, especially for long-term tissue acceptance response. Mechanotransduction activities of TNA nanosurface could involve the cytoskeleton remodeling mechanism. However, there is no clear insight into TNA mechano-cytoskeleton remodeling activities, especially computational approaches. Epithelial cells have played critical interface between biomedical implant surface and tissue acceptance, particularly for long-term interaction. Therefore, this study investigates genomic responses that are responsible for cell-TNA mechano-stimulus using epithelial cells model. Findings suggested that cell-TNA interaction may improve structural and extracellular matrix (ECM) support on the cells as an adaptive response toward the nanosurface topography. More specifically, the surface topography of the TNA might improve the cell polarity and adhesion properties via the interaction of the plasma membrane and intracellular matrix responses. TNA nanosurface might engross the cytoskeleton remodeling activities for multidirectional cell movement and cellular protrusions on TNA nanosurface. These observations are supported by the molecular docking profiles that determine proteins' in silico binding mechanism on TNA. This active cell-surface revamping would allow cells to adapt to develop a protective barrier toward TNA nanosurface, thus enhancing biocompatibility properties distinctly for long-term interaction. The findings from this study will be beneficial toward nano-molecular knowledge of designing functional nanosurface technology for advanced medical implant applications.

Midkine promotes metastasis and therapeutic resistance via mTOR/RPS6 in uveal melanoma

Uveal melanoma is a rare form of melanoma that originates in the eye, exerts widespread therapeutic resistance and displays an inherent propensity for hepatic metastases. Since metastatic disease is characterized by poor survival, there is an unmet clinical need to identify new therapeutic targets in uveal melanoma. Here, we show that the pleiotropic cytokine midkine is expressed in uveal melanoma. Midkine expression in primary uveal melanoma significantly correlates with poor survival and is elevated in patients that develop metastatic disease. Monosomy 3 and histopathological staging parameters are associated with midkine expression. In addition, we demonstrate that midkine promotes survival, migration across a barrier of hepatic sinusoid endothelial cells and resistance to AKT/mTOR inhibition. Furthermore, midkine is secreted and mediates mTOR activation by maintaining phosphorylation of the mTOR target RPS6 in uveal melanoma cells. Therefore, midkine is identified as a uveal melanoma cell survival factor that drives metastasis and therapeutic resistance, and could be exploited as a biomarker as well as a new therapeutic target. Implications: Midkine is identified as a survival factor that drives liver metastasis and therapeutic resistance in melanoma of the eye.

Pleiotrophin Interaction with Synthetic Glycosaminoglycan Mimetics

Chondroitin sulfate (CS) E is the natural ligand for pleiotrophin (PTN) in the central nervous system (CNS) of the embryo. Some structures of PTN in solution have been solved, but no precise location of the binding site has been reported yet. Using ¹⁵N-labelled PTN and HSQC NMR experiments, we studied the interactions with a synthetic CS-E tetrasaccharide corresponding to the minimum binding sequence. The results agree with the data for larger GAG (glycosaminoglycans) sequences and confirm our hypothesis that a synthetic tetrasaccharide is long enough to fully interact with PTN. We hypothesize that the central region of PTN is an intrinsically disordered region (IDR) and could modify its properties upon binding. The second tetrasaccharide has two benzyl groups and shows similar effects on PTN. Finally, the last measured compound aggregated but beforehand, showed a behavior compatible with a slow exchange in the NMR time scale. We propose the same binding site and mode for the tetrasaccharides with and without benzyl groups.

Anticancer Effects of New Ceramides Isolated from the Red Sea Red Algae Hypnea musciformis in a Model of Ehrlich Ascites Carcinoma: LC-HRMS Analysis Profile and Molecular Modeling

Different classes of phytochemicals were previously isolated from the Red Sea algae Hypnea musciformis as sterols, ketosteroids, fatty acids, and terpenoids. Herein, we report the isolation of three fatty acids-docosanoic acid 4, hexadecenoic acid 5, and alpha hydroxy octadecanoic acid 6-as well as three ceramides-A (1), B (2), and C (3)-with 9-methyl-sphinga-4,8-dienes and phytosphingosine bases. Additionally, different phytochemicals were determined using the liquid chromatography coupled with electrospray ionization high-resolution mass spectrometry (LC-ESI-HRMS) technique. Ceramides A (1) and B (2) exhibited promising in vitro cytotoxic activity against the human breast adenocarcinoma (MCF-7) cell line when compared with doxorubicin as a positive control. Further in vivo study and biochemical estimation in a mouse model of Ehrlich ascites carcinoma (EAC) revealed that both ceramides A (1) and B (2) at doses of 1 and 2 mg/kg, respectively, significantly decreased the tumor size in mice inoculated with EAC cells. The higher dose (2 mg/kg) of ceramide B (2) particularly expressed the most pronounced decrease in serum levels of vascular endothelial growth factor -B (VEGF-B) and tumor necrosis factor-α (TNF-α) markers, as well as the expression levels of the growth factor midkine in tumor tissue relative to the EAC control group. The highest expression of apoptotic factors, p53, Bax, and caspase 3 was observed in the same group that received 2 mg/kg of ceramide B (2). Molecular docking simulations suggested that ceramides A (1) and B (2) could bind in the deep grove between the H2 helix and the Ser240-P250 loop of p53, preventing its interaction with MDM2 and leading to its accumulation. In conclusion, this study reports the cytotoxic, apoptotic, and antiangiogenic effects of ceramides isolated from the Red Sea algae Hypnea musciformis in an experimental model of EAC.

Diagnostic performance of Midkine ratios in fine-needle aspirates for evaluation of Cytologically indeterminate thyroid nodules

Background

Fine-needle aspiration cytology (FNAC) is a basic diagnostic tool for thyroid nodules. However, 15–30% of nodules are cytologically indeterminate. Midkine (MK), a pleiotropic growth factor, is often upregulated in patients with cancers. This study aimed to evaluate the role of MK and its ratios in fine-needle aspirates (FNA) for predicting thyroid malignancy.

Methods

This retrospective study included patients with thyroid nodules who underwent preoperative FNA and/or thyroidectomy between April 2017 and September 2017. MK levels in FNA washout were measured by enzyme-linked immunosorbent assay, and thyroglobulin (TG) and free thyroxine (FT4) levels in FNA washout were measured by chemiluminescent immunometric assays.

Results

A total of 217 patients with 242 nodules were included in this study. The concentrations of TG, FT4, MK/TG, MK/FT4, and FT4/MK were significantly different between papillary thyroid carcinomas and benign thyroid nodules. Both MK/TG and MK/FT4 ratios were positively correlated with maximum tumor diameter, extrathyroidal extension, and T and N stages. The area under the curve for MK/TG was 0.719 with a cutoff value of 55.57 ng/mg, while the area under the curve for MK/FT4 was 0.677 with a cutoff value of 0.11 μg/pmol. FNAC in combination with MK/FT4 had a higher sensitivity (95% vs. 91%) and accuracy (96% vs. 92%) than FNAC alone for cytologically indeterminate specimens, those of unknown significance, or those suspected of malignancy.

Conclusions

MK/FT4 and MK/TG may have diagnostic utility for evaluation of papillary thyroid carcinomas, particularly for cytologically indeterminate thyroid nodules.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13000-021-01150-y.

Comparison of diagnostic accuracy of Midkine and AFP for detecting hepatocellular carcinoma: a systematic review and meta-analysis

Objective: Midkine (MDK) has been proposed as one of the most promising markers for hepatocellular carcinoma (HCC). This meta-analysis was conducted to compare the diagnostic accuracy of MDK and α-fetoprotein (AFP) for HCC.

Methods: We systematically searched PubMed/MEDLINE, Ovid/EMBASE, and the Cochrane Library for all relevant studies up to 18 May 2019. The Revised Quality Assessment for Studies of Diagnostic Accuracy tool (QUADAS-2) was used to assess the methodological quality of the included studies. The sensitivity, specificity, and the area under the curve (AUC) of MDK and AFP for detecting HCC were pooled using random-effects model.

Results: Seventeen studies from five articles with a total of 1122 HCC patients and 2483 controls were included. The summary estimates using MDK and AFP for detecting HCC were as follows: sensitivity, 85 vs 52%, specificity, 82 vs 94%, and AUC, 0.90 vs 0.83. The summary estimates using MDK and AFP for detecting hepatitis virus-related HCC as follows: sensitivity, 93 vs 74%, specificity, 85 vs 97%, and AUC, 0.95 vs 0.97. The summary estimates using MDK and AFP for detecting early-stage HCC were as follows: sensitivity, 83.5 vs 44.4%, specificity, 81.7 vs 84.8%, and AUC, 0.87 vs 0.52. The summary estimates using MDK for detecting AFP-negative HCC as follows: sensitivity, 88.5%, specificity, 83.9%, and AUC, 0.91.

Conclusion: MDK is more accurate than AFP in diagnosing HCC, especially for early-stage HCC and AFP-negative HCC. Both MDK and AFP had excellent diagnostic performance for hepatitis virus-related HCC.

Gene networks and transcriptional regulators associated with liver cancer development and progression

BACKGROUND

Treatment options for hepatocellular carcinoma (HCC) are limited, and overall survival is poor. Despite the high frequency of this malignoma, its basic disease mechanisms are poorly understood. Therefore, the aim of this study was to use different methodological approaches and combine the results to improve our knowledge on the development and progression of HCC.

METHODS

Twenty-three HCC samples were characterized by histological, morphometric and cytogenetic analyses, as well as comparative genomic hybridization (aCGH) and genome-wide gene expression followed by a bioinformatic search for potential transcriptional regulators and master regulatory molecules of gene networks.

RESULTS

Histological evaluation revealed low, intermediate and high-grade HCCs, and gene expression analysis split them into two main sets: GE1-HCC and GE2-HCC, with a low and high proliferation gene expression signature, respectively. Array-based comparative genomic hybridization demonstrated a high level of chromosomal instability, with recurrent chromosomal gains of 1q, 6p, 7q, 8q, 11q, 17q, 19p/q and 20q in both HCC groups and losses of 1p, 4q, 6q, 13q and 18q characteristic for GE2-HCC. Gene expression and bioinformatics analyses revealed that different genes and gene regulatory networks underlie the distinct biological features observed in GE1-HCC and GE2-HCC. Besides previously reported dysregulated genes, the current study identified new candidate genes with a putative role in liver cancer, e.g. C1orf35, PAFAH1B3, ZNF219 and others.

CONCLUSION

Analysis of our findings, in accordance with the available published data, argues in favour of the notion that the activated E2F1 signalling pathway, which can be responsible for both inappropriate cell proliferation and initial chromosomal instability, plays a pivotal role in HCC development and progression. A dedifferentiation switch that manifests in exaggerated gene expression changes might be due to turning on transcriptional co-regulators with broad impact on gene expression, e.g. POU2F1 (OCT1) and NFY, as a response to accumulating cell stress during malignant development. Our findings point towards the necessity of different approaches for the treatment of HCC forms with low and high proliferation signatures and provide new candidates for developing appropriate HCC therapies.

New Blood Biomarkers for the Diagnosis of AFP-Negative Hepatocellular Carcinoma

An early diagnosis of hepatocellular carcinoma (HCC) followed by effective treatment is currently critical for improving the prognosis and reducing the associated economic burden. Alpha-fetoprotein (AFP) is the most widely used biomarker for HCC diagnosis. Based on elevated serum AFP levels as well as typical imaging features, AFP-positive HCC (APHC) can be easily diagnosed, but AFP-negative HCC (ANHC) is not easily detected due to lack of ideal biomarkers and thus mainly reliance on imaging. Imaging for the diagnosis of ANHC is probably insufficient in sensitivity and/or specificity because most ANHC tumors are small and early-stage HCC, and it is involved in sophisticated techniques and high costs. Moreover, ANHC accounts for nearly half of HCC and exhibits a better prognosis compared with APHC. Therefore, the diagnosis of ANHC in clinical practice has been a critical issue for the early treatment and prognosis improvement of HCC. In recent years, tremendous efforts have been made to discover new biomarkers complementary to AFP for HCC diagnosis. In this review, we systematically review and discuss the recent advances of blood biomarkers for HCC diagnosis, including DNA biomarkers, RNA biomarkers, protein biomarkers, and conventional laboratory metrics, focusing on their diagnostic evaluation alone and in combination, in particular on their diagnostic performance for ANHC.

Midkine (MDK) growth factor: a key player in cancer progression and a promising therapeutic target

Midkine is a heparin-binding growth factor, originally reported as the product of a retinoic acid-responsive gene during embryogenesis, but currently viewed as a multifaceted factor contributing to both normal tissue homeostasis and disease development. Midkine is abnormally expressed at high levels in various human malignancies and acts as a mediator for the acquisition of critical hallmarks of cancer, including cell growth, survival, metastasis, migration, and angiogenesis. Several studies have investigated the role of midkine as a cancer biomarker for the detection, prognosis, and management of cancer, as well as for monitoring the response to cancer treatment. Moreover, several efforts are also being made to elucidate its underlying mechanisms in therapeutic resistance and immunomodulation within the tumor microenvironment. We hereby summarize the current knowledge on midkine expression and function in cancer development and progression, and highlight its promising potential as a cancer biomarker and as a future therapeutic target in personalized cancer medicine.

Midkine-a Is Required for Cell Cycle Progression of Müller Glia during Neuronal Regeneration in the Vertebrate Retina

In the retina of zebrafish, Müller glia have the ability to reprogram into stem cells capable of regenerating all classes of retinal neurons and restoring visual function. Understanding the cellular and molecular mechanisms controlling the stem cell properties of Müller glia in zebrafish may provide cues to unlock the regenerative potential in the mammalian nervous system. Midkine is a cytokine/growth factor with multiple roles in neural development, tissue repair, and disease.

In the retina of zebrafish, Müller glia have the ability to reprogram into stem cells capable of regenerating all classes of retinal neurons and restoring visual function. Understanding the cellular and molecular mechanisms controlling the stem cell properties of Müller glia in zebrafish may provide cues to unlock the regenerative potential in the mammalian nervous system. Midkine is a cytokine/growth factor with multiple roles in neural development, tissue repair, and disease. In midkine-a loss-of-function mutants of both sexes, Müller glia initiate the appropriate reprogramming response to photoreceptor death by increasing expression of stem cell-associated genes, and entering the G₁ phase of the cell cycle. However, transition from G₁ to S phase is blocked in the absence of Midkine-a, resulting in significantly reduced proliferation and selective failure to regenerate cone photoreceptors. Failing to progress through the cell cycle, Müller glia undergo reactive gliosis, a pathological hallmark in the injured CNS of mammals. Finally, we determined that the Midkine-a receptor, anaplastic lymphoma kinase, is upstream of the HLH regulatory protein, Id2a, and of the retinoblastoma gene, p130, which regulates progression through the cell cycle. These results demonstrate that Midkine-a functions as a core component of the mechanisms that regulate proliferation of stem cells in the injured CNS.

SIGNIFICANCE STATEMENT The death of retinal neurons and photoreceptors is a leading cause of vision loss. Regenerating retinal neurons is a therapeutic goal. Zebrafish can regenerate retinal neurons from intrinsic stem cells, Müller glia, and are a powerful model to understand how stem cells might be used therapeutically. Midkine-a, an injury-induced growth factor/cytokine that is expressed by Müller glia following neuronal death, is required for Müller glia to progress through the cell cycle. The absence of Midkine-a suspends proliferation and neuronal regeneration. With cell cycle progression stalled, Müller glia undergo reactive gliosis, a pathological hallmark of the mammalian retina. This work provides a unique insight into mechanisms that control the cell cycle during neuronal regeneration.

Inhibition of midkine by metformin can contribute to its anticancer effects in malignancies: A proposal mechanism of action of metformin in context of endometrial cancer prevention and therapy

Metformin, a drug widely used in the treatment of type II diabetes mellitus (T2DM), has been the focus of interest as a potential therapeutic agent for certain types of malignancies, including gynaecological cancers [i.e. endometrial cancer (EC)]. Although the exact mechanism behind the potential anticancer activity of metformin is still not completely understood, certain studies have suggested that different effects on cell functions, such as inhibition of cell migration, apoptosis and tumor cell proliferation, are involved in its preventive and therapeutic effects in certain types of malignancies, including EC. In contrast, midkine (MK), a heparin-binding growth factor and cytokine, which induces carcinogenesis and chemoresistance, promotes the development and progression of many malignant tumours by increasing diverse cell functions such as cell proliferation, cell survival and antiapoptotic activities via mainly the activation of phosphatidyl inositol 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathways. The same pathways are also subject to certain therapeutic effects of metformin, although this cytokine and this drug have some different mechanism of action pathways as well. Taken together, MK and metformin appear to have opposite effects in various biological processes such as apoptosis, cell proliferation, cell survival, cell migration, and angiogenesis. On the other hand, MK activates PI3K and MAPK cell signal pathways, whereas metformin inhibits these two pathways. It seems likely that almost all the pathways and cell functions, which play important roles in malignancies, are inhibited by metformin and activated by MK. Given the opposite relationship between the actions of metformin and MK, we hypothesize that metformin may act like a novel MK inhibitor in some malignancies. We also discuss the possible relationship between metformin and MK in the context of EC, the most common gynecological cancer worldwide, which incidence is rising rapidly, in parallel with the increase in obesity, T2DM and insulin resistance. In this respect, the therapeutic use of metformin may improve the survival of EC or other cancers, via inhibiting or overcoming the unwanted effects of MK in carcinogenesis.

Plasma Midkine Is Associated With 28-Day Mortality and Organ Function in Sepsis

BACKGROUND

Midkine has been reported to play a crucial role in inflammatory, hypoxia, and tissue injury processes. We aimed to investigate plasma midkine in septic patients and its association with 28-day mortality and organ function.

METHODS

Septic patients admitted to the Department of Critical Care Medicine, Zhongda Hospital, a tertiary hospital, from November 2017 to March 2018 were enrolled in the study. The baseline characteristics of the septic patients were recorded at admission. A peripheral blood sample was obtained at admission, and plasma midkine levels were evaluated with an immunoassay. All patients were followed up with for 28 days, with all-cause mortality being recorded.

RESULTS

A total of 26 septic patients were enrolled, which included 18 survivors and 8 nonsurvivors at day 28. Plasma midkine levels were significantly elevated in the nonsurvivor group compared with the survivors (ng/L, 763.6 [404.7-1305], 268.5 [147.8-511.4]; P = .0387]. Plasma midkine levels were elevated in septic patients with moderate/severe acute respiratory distress syndrome (ARDS) compared with patients with non/mild ARDS (ng/L, 522.3 [336.6-960.1] vs 243.8 [110.3-478.9]; P = .0135) and in those with acute kidney injury compared with those without (ng/L, 489.8 [259.2-1058] vs 427.9 [129.6-510.3]; P = .0973). Changes in plasma midkine levels were also associated with extravascular lung water index (P = .063) and pulmonary vascular permeability index (P = .049).

CONCLUSIONS

Plasma midkine was associated with 28-day mortality, as well as pulmonary and kidney injury, in septic patients.

Midkine drives cardiac inflammation by promoting neutrophil trafficking and NETosis in myocarditis

Heart failure due to dilated cardiomyopathy is frequently caused by myocarditis. However, the pathogenesis of myocarditis remains incompletely understood. Here, we report the presence of neutrophil extracellular traps (NETs) in cardiac tissue of patients and mice with myocarditis. Inhibition of NET formation in experimental autoimmune myocarditis (EAM) of mice substantially reduces inflammation in the acute phase of the disease. Targeting the cytokine midkine (MK), which mediates NET formation in vitro, not only attenuates NET formation in vivo and the infiltration of polymorphonuclear neutrophils (PMNs) but also reduces fibrosis and preserves systolic function during EAM. Low-density lipoprotein receptor-related protein 1 (LRP1) acts as the functionally relevant receptor for MK-induced PMN recruitment as well as NET formation. In summary, NETosis substantially contributes to the pathogenesis of myocarditis and drives cardiac inflammation, probably via MK, which promotes PMN trafficking and NETosis. Thus, MK as well as NETs may represent novel therapeutic targets for the treatment of cardiac inflammation.

Changes of serum midkine as a dynamic prognostic factor to monitor disease status in papillary thyroid cancer

This study aimed to investigate the value of dynamic changes of midkine (MK) to monitor post-surgical patients with papillary thyroid cancer (PTC) who were managed with I therapies.MK concentration at initial I ablation therapy (MK1) as well as 10 to 12 months thereafter (MK2) was evaluated. And the dynamic changes of thyroglobulin (Tg) were compared (Tg1 and Tg2). Patients with MK influencing co-morbidities and with positive thyroglobulin antibodies were excluded. Concentrations of MK were measured by enzyme-linked immunosorbent assay.There were 241 PTC patients (36 males, 205 females) enrolled, 55 cases had metastases (8 males, 47 females) during their follow-up. Cox regression showed if Tg2 decreased (compared with Tg1), but not to less than 1.0ng/mL under TSH stimulation, the risk of metastases was 12.554 times more than if it could decrease to the optimal level. If Tg2 increased, the risk is 19.461 times higher. As for MK, if MK2 level decreased (compared with MK1), but not to a normal level, the risk of metastases is 3.006. If MK2 level increased, it would be 5.030 likely to had metastases.Our results indicated that MK could potentially be used as a disease monitoring biomarker for PTC, although inferior to Tg.

Clinical value of jointly detection pleural fluid Midkine, pleural fluid adenosine deaminase, and pleural fluid carbohydrate antigen 125 in the identification of nonsmall cell lung cancer-associated malignant pleural effusion

BACKGROUND

Midkine (MK) level has been shown to be elevated in serum of patients with nonsmall cell lung cancer (NSCLC). However, the diagnostic value of MK in pleural effusion in NSCLC has not been well validated and established.

METHODS

Samples of NSCLC-associated malignant pleural effusions (MPE) and benign effusions (BPE) were collected. The pleural fluid MK (pMK), pleural fluid adenosine deaminase (pADA), pleural fluid lactate dehydrogenase (pLDH), pleural fluid glucose (pGLU), pleural fluid ferritin (pFER), pleural fluid CA199 (pCA199), pleural fluid CA125 (pCA125), pleural effusion white cell count (pWBC), and pleural effusion red cell count (pRBC) were analyzed, and the clinical data of each group were collected for statistical analysis.

RESULT

The level of pMK, pCA125, pMK + pCA125, and pMK + pCA125 + pADA in the MPE was significantly higher than the BPE group (P = .003, .000, .000, .000). The pADA level in the BPE was significantly higher than the MPE group (P = .003). It showed that the area under the ROC curve (AUC) (0.816) of jointly detection pMK, pCA125, and pADA was significantly higher than other markers for the diagnosis of MPE. Therefore, joint detection of pMK + pCA125 + pADA suggested that the sensitivity, specificity, and AUC was 82.54%, 74.19% at the cutoff 0.47 and diagnostic performance was higher than others.

CONCLUSION

Joint detection of pMK + pCA125 + pADA can be used as a good indicator for the identification of MPE of NSCLC.

Midkine promotes hepatocellular carcinoma metastasis by elevating anoikis resistance of circulating tumor cells

Midkine is overexpressed in hepatocellular carcinoma (HCC) and plays a role in tumor progression, but less is known about its role in resistance of circulating tumor cells (CTCs) to anoikis which leading to recurrence and metastasis. The aim of the present study was to analyze whether midkine was associated with HCC progression with anoikis resistance. We found that cultured HCC cells were more resistant to anoikis, which paralleled midkine expression, and midkine treatment significantly inhibited anoikis in a dose-dependent manner. Furthermore, in in vitro and in vivo assays, knockdown of midkine resulted in significant sensitivity to anoikis, decreased cell survival and significantly decreased tumor occurrence rate. Patients with midkine-elevated HCC had higher CTC counts and less apoptotic CTCs, as well as significantly higher recurrence rate and shorter recurrence-free interval. To understand the molecular mechanism underlying the midkine with HCC progression, we performed in vitro and in vivo studies. We found that midkine plays an important role in enhancement of HCC cell resistance to anoikis, thereby promoting subsequent metastasis. Activation of PI3K/Akt/NF-κB/TrkB signaling by midkine-activated anaplastic lymphomakinase (ALK) is responsible for anoikis resistance.

Positive expression of Midkine predicts early recurrence and poor prognosis of initially resectable combined hepatocellular cholangiocarcinoma

Background

Post-surgical prognosis is usually poor for combined hepatocellular cholangiocarcinoma (CHCC-CC), a rare primary liver cancer. Although midkine (MK) is a prognostic biomarker for several known cancers, it is not known whether it can be used as such in resectable CHCC-CC. This study examined whether MK expression can predict recurrence and survival in patients with resectable CHCC-CC.

Methods

We retrospectively enrolled 52 patients with resectable CHCC-CC who had received curative hepatic resections. MK expression was assessed in post-surgical immunohistochemical studies of specimens in paraffin blocks. Clinical outcomes were analyzed from medical records.

Results

Two-year disease-free and three-year overall survival rates were 42.1% and 44.6%. MK was expressed in 30 patients. Univariate analysis showed patients positively expressing MK had a significantly poorer 2-year disease free and three-year overall survival. Multivariate analysis found positive MK expression independently predicted recurrence.

Conclusions

Positive expression of MK predicts poor prognosis in patients with resectable CHCC-CC.

Prognostic value of Midkine expression in patients with solid tumors: a systematic review and meta-analysis

Background

Accumulated studies have shown the important role of Midkine (MDK) protein in various solid tumors and indicated its correlation with patients' survival. This meta-analysis was performed to further explore the prognostic value of MDK expression in solid tumors.

Materials and Methods

We collected the literatures through searching PubMed, Embase and the Cochrane Library (last up to April 10, 2017) to assess the effect of MDK on survival in solid tumor patients. The STATA 12.0 software was used for the meta-analysis. Fixed-effects models or random-effects models were used to estimate the pooled hazard ratios (HRs) for overall survival (OS).

Results

A total of 2097 patients from 17 observational studies were summarized. High expression of MDK was notably associated with worse OS in solid tumor patients. (pooled HR = 1.96; 95% CI = 1.67-2.31). The subgroup analysis of tumor type demonstrated negative impact of elevated MDK on OS in most solid tumor patients (P < 0.05), while MDK had no relevance with OS in the patients with OSCC (pooled HR = 1.68; 95% CI = 0.84-3.36; P = 0.145) or HNSCC (pooled HR = 1.56; 95% CI = 0.96-2.51; P = 0.075).

Conclusions

The present meta-analysis clarifies that MDK is a potential prognostic biomarker in solid tumor patients. Future large-scale prospective clinical trials are needed to determine the prognostic value of MDK in solid tumor patients.

Whole-body imaging of lymphovascular niches identifies pre-metastatic roles of midkine

Cutaneous melanoma is a type of cancer with an inherent potential for lymph node colonization, which is generally preceded by neolymphangiogenesis. However, sentinel lymph node removal does not necessarily extend the overall survival of patients with melanoma. Moreover, lymphatic vessels collapse and become dysfunctional as melanomas progress. Therefore, it is unclear whether (and how) lymphangiogenesis contributes to visceral metastasis. Soluble and vesicle-associated proteins secreted by tumours and/or their stroma have been proposed to condition pre-metastatic sites in patients with melanoma. Still, the identities and prognostic value of lymphangiogenic mediators remain unclear. Moreover, our understanding of lymphangiogenesis (in melanomas and other tumour types) is limited by the paucity of mouse models for live imaging of distal pre-metastatic niches. Injectable lymphatic tracers have been developed, but their limited diffusion precludes whole-body imaging at visceral sites. Vascular endothelial growth factor receptor 3 (VEGFR3) is an attractive 'lymphoreporter' because its expression is strongly downregulated in normal adult lymphatic endothelial cells, but is activated in pathological situations such as inflammation and cancer. Here, we exploit this inducibility of VEGFR3 to engineer mouse melanoma models for whole-body imaging of metastasis generated by human cells, clinical biopsies or endogenously deregulated oncogenic pathways. This strategy revealed early induction of distal pre-metastatic niches uncoupled from lymphangiogenesis at primary lesions. Analyses of the melanoma secretome and validation in clinical specimens showed that the heparin-binding factor midkine is a systemic inducer of neo-lymphangiogenesis that defines patient prognosis. This role of midkine was linked to a paracrine activation of the mTOR pathway in lymphatic endothelial cells. These data support the use of VEGFR3 reporter mice as a 'MetAlert' discovery platform for drivers and inhibitors of metastasis.

Proteomic and transcriptomic analyses to explain the pleiotropic effects of Ankaferd blood stopper

Ankaferd blood stopper is a standardized mixture of the plants Thymus vulgaris, Glycyrrhiza glabra, Vitis vinifera, Alpinia officinarum, and Urtica dioica and has been used as a topical hemostatic agent and with its clinical application established in randomized controlled trials and case reports. Ankaferd has been successfully used in gastrointestinal endobronchial mucosal and cutaneous bleedings and also in abdominal, thoracic, dental and oropharyngeal, and pelvic surgeries. Ankaferd’s hemostatic action is thought to form a protein complex with coagulation factors that facilitate adhesion of blood components. Besides its hemostatic action, Ankaferd has demonstrated pleiotropic effects, including anti-neoplastic and anti-microbial activities and tissue-healing properties; the underlying mechanisms for these have not been well studied. Ankaferd’s individual components were determined by proteomic and chemical analyses. Ankaferd also augments transcription of some transcription factors which is shown with transcriptomic analysis. The independent effects of these ingredients and augmented transcription factors are not known precisely. Here, we review what is known of Ankaferd blood stopper components from chemical, proteomic, and transcriptomic analyses and propose that individual components can explain some pleiotropic effects of Ankaferd. Certainly more research is needed focusing on individual ingredients of Ankaferd to elucidate their precise and effects.

Dual inhibition of P-glycoprotein and midkine may increase therapeutic effects of anticancer drugs

Multidrug resistance (MDR) to chemotherapy may significantly affect the outcome of cancer treatment. ATP-dependent drug efflux pumps, including P-glycoprotein (P-gp), contribute to the resistance of various chemotherapeutic agents. Overexpression of P-gp in tumor cells induces chemoresistance via pumping the anticancer drugs out of the cells. In addition to taking part in many biological processes such as development, reproduction and repair, midkine (MK) also plays important roles in the pathogenesis of malignant diseases as well as in the regulation of MDR. Although, the mechanisms of action of P-gp and MK are different, overexpression of both proteins prevents the accumulation of many chemotherapeutics in tumor cells, leading to decreased therapeutic effects of anticancer drugs. Therefore, identification of the result of dual inhibition of P-gp and MK in overcoming chemoresistance may enhance the likelihood for a more efficient chemotherapy.

Diagnostic accuracy of ELISA for detecting serum Midkine in cancer patients

Midkine (MK) has been reported as the potential novel diagnostic biomarker for cancer in several studies, but their results were controversial. Therefore, we performed a diagnostic meta-analysis to assess the diagnostic value of serum MK in cancer patients. A systematic electronic and manual search was performed for relevant literatures through several databases up to June 1, 2017. The quality of the studies included in the meta-analysis was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. All analyses were conducted using stata12.0 software. Ten studies collectively included 1119 cancer patients and 1441 controls met the eligible criteria. The summary estimates were: sensitivity 0.78 (95% CI = 0.68-0.85), specificity 0.83 (95% CI = 0.72-0.90), positive likelihood ratio 4,54 (95% CI = 2.64-7.80), negative likelihood 0.27 (95% CI = 0.18-0.40), diagnostic odds ratio 16.79 (95% CI = 7.17-39.33), and area under the curve 0.87 (95% CI = 0.84-0.89). Publication bias was suggested by Deeks' funnel plot asymmetry test (P = 0.92). According to our results, serum MK has greater diagnostic value in diagnosing cancer, however, more reliable studies in larger cohort should be conducted to evaluate the diagnostic accuracy of serum MK.

The inflammatory phase of fracture healing is influenced by oestrogen status in mice

Background

Fracture healing is known to be delayed in postmenopausal, osteoporotic females under oestrogen-deficient conditions. Confirming this, experimental studies demonstrated impaired callus formation in ovariectomised animals. Oestrogen-deficiency is known to affect the immune system and the inflammatory response during wound healing. Because a balanced immune response is required for proper bone healing, we were interested to ascertain whether the early immune response after facture is affected by oestrogen depletion.

Methods

To address the above question, female mice received either a bilateral ovariectomy (OVX) or were sham-operated, and femur osteotomy was performed 8 weeks after OVX/sham operation. The effects of OVX on the presence of immune cells and pro-inflammatory cytokines were evaluated by flow cytometry and immunohistochemistry of the fracture calli on days 1 and 3 after fracture.

Results

One day after fracture, immune cell numbers and populations in the fracture haematoma did not differ between OVX- and sham-mice. However, on day 3 after fracture, OVX-mice displayed significantly greater numbers of neutrophils. Local expression of the oestrogen-responsive and pro-inflammatory cytokine midkine (Mdk) and interleukin-6 (IL-6) expression in the fracture callus were increased in OVX-mice on day 3 after fracture compared with sham-mice, indicating that both factors might be involved in the increased presence of neutrophils. Confirming this, Mdk-antibody treatment decreased the number of neutrophils in the fracture callus and reduced local IL-6 expression in OVX-mice.

Conclusions

These data indicate that oestrogen-deficiency influences the early inflammatory phase after fracture. This may contribute to delayed fracture healing after oestrogen depletion.

Heparanase: Potential roles in multiple sclerosis

Heparanase is a heparan sulfate degrading enzyme that cleaves heparan sulfate (HS) chains present on HS proteoglycans (HSPGs), and has been well characterized for its roles in tumor metastasis and inflammation. However, heparanase is emerging as a contributing factor in the genesis and severity of a variety of neurodegenerative diseases and conditions. This is in part due to the wide variety of HSPGs on which the presence or absence of HS moieties dictates protein function. This includes growth factors, chemokines, cytokines, as well as components of the extracellular matrix (ECM) which in turn regulate leukocyte infiltration into the CNS. Roles for heparanase in stroke, Alzheimer's disease, and glioma growth have been described; roles for heparanase in other disease such as multiple sclerosis (MS) are less well established. However, given its known roles in inflammation and leukocyte infiltration, it is likely that heparanase also contributes to MS pathology. In this review, we will briefly summarize what is known about heparanase roles in the CNS, and speculate as to its potential role in regulating disease progression in MS and its animal model EAE (experimental autoimmune encephalitis), which may justify testing of heparanase inhibitors for MS treatment.

MPA Modulates Tight Junctions' Permeability via Midkine/PI3K Pathway in Caco-2 Cells: A Possible Mechanism of Leak-Flux Diarrhea in Organ Transplanted Patients

Mycophenolic acid (MPA) is prescribed to prevent allograft rejection in organ transplanted patients. However, its use is sporadically linked to leak flux diarrhea and other gastrointestinal (GI) disturbances in around 75% of patients through yet unknown mechanisms. Recently, we identified Midkine as a modulator of tight junctions (TJs) permeability in MPA treated Caco-2 monolayer. In the present study, we investigated the possible involvement of Midkine dependent PI3K pathway in alteration of TJs under MPA treatment. Caco-2 cells were grown as monolayer to develop TJs and were treated for 72 h with DMSO (control) or MPA in presence and absence of Midkine inhibitor (iMDK) or PI3K inhibitors (LY/AMG). Caco-2 monolayer integrity was assessed by transepithelial electrical resistance (TEER) and FITC-dextran assays. Our functional assays showed that PI3K inhibitors (LY/AMG) can significantly inhibit the compromised TJs integrity of MPA-treated Caco-2 cells monolayer. Chromatin immunoprecipitation analyses showed a significant epigenetic activation of Midkine, PI3K, Cdx-2, and Cldn-2 genes and epigenetic repression of Cldn-1 gene after MPA treatment. The MPA-induced epigenetic alterations were further confirmed by mRNA and protein expression analysis. Collectively, our data shows that PI3K pathway as the downstream target of Midkine which in turn modulates p38MAPK and pAKT signaling to alter TJs permeability in Caco-2 cell monolayers treated with MPA. These results highlight the possible use of either Midkine or PI3K inhibitors as therapeutic agents to prevent MPA induced GI disturbances.

Serum midkine as a surrogate biomarker for metastatic prediction in differentiated thyroid cancer patients with positive thyroglobulin antibody

Serum thyroglobulin (Tg) is the main post-operative tumor biomarker for patients with differentiated thyroid cancer (DTC). However, the presence of thyroglobulin antibodies (TgAb) can interfere with Tg level and invalidate the test. In this study, we aimed to investigate the predicative value of midkine (MK) as a cancer biomarker for DTC patients with positive TgAb before the first 131I therapy. MK levels were measured by enzyme-linked immunosorbent assay in 151 recruited DTC patients after exercising strict inclusion and exclusion criteria. There were 28 TgAb positive DTC patients with metastases and 123 DTC patients without metastases. The value of pre-131I-ablative MK to predict metastasis was assessed by receiver operating characteristic (ROC) curves in these two groups of patients. MK levels in the TgAb positive DTC patients were significantly higher than the DTC patients without metastases. ROC showed good predictability of MK, with an area under the curve of 0.856 (P < 0.001), and a diagnostic accuracy of 83% at the optimal cut-off value of 550 pg/ml. In conclusion, we show that MK can potentially be used as a surrogate biomarker for predicting DTC metastases when Tg is not suitable due to TgAb positivity.

Lithium chloride has a biphasic effect on prostate cancer stem cells and a proportional effect on midkine levels

Prostate cancer (PCa) is the second most frequent type of cancer in men worldwide and the levels of differentiation growth factor midkine (MK) are increased in PCa. Cancer and/or the treatment process itself may lead to psychiatric disorders. Lithium chloride (LiCl) has anti-manic properties and has been used in cancer therapy; however, it has a queried safety profile. In addition, cancer stem cells are responsible for the heterogeneous phenotype of tumor cells; they are involved in progression, metastasis, recurrence and therapy resistance in various cancer types. The aims of the present study were to investigate the effect of different concentrations of LiCl on PCa stem cells (whether a shift from tumorigenic to non-tumorigenic cells occurs) and to determine if these results can be explained through changes in MK levels. Monolayer and spheroid cultures of human prostate stem cells and non-stem cells were incubated with low (1, 10 µM) and high (100, 500 µM) concentrations of LiCl for 72 h. Cell proliferation, apoptotic indices, MK levels and ultrastructure were evaluated. Cells stimulated with low concentrations showed high proliferation, low apoptotic indices, high MK levels and more healthy ultrastructure. Opposite results were obtained at high concentrations. Furthermore, stem cells were more sensitive to stimulation and more resistant to inhibition than non-stem cells. LiCl exhibited concentration-dependent effects on stem cell and non-stem cell groups. MK levels were not involved in the biphasic effect of LiCl; however, they were proportionally affected. To the best of our knowledge, the present study was the first to show the effect of LiCl on PCa stem cells through MK.

Midkine Increases Diagnostic Yield in AFP Negative and NASH-Related Hepatocellular Carcinoma

Robust biomarkers for population-level hepatocellular carcinoma (HCC) surveillance are lacking. We compared serum midkine (MDK), dickkopf-1 (DKK1), osteopontin (OPN) and AFP for HCC diagnosis in 86 HCC patients matched to 86 cirrhotics, 86 with chronic liver disease (CLD) and 86 healthy controls (HC). Based on the performance of each biomarker, we assessed a separate longitudinal cohort of 28 HCC patients, at and before cancer diagnosis. Serum levels of MDK and OPN were higher in HCC patients compared to cirrhosis, CLD and HC groups. DKK1 was not different between cases and controls. More than half of HCC patients had normal AFP. In this AFP-negative HCC cohort, 59.18% (n = 29/49) had elevated MDK, applying the optimal cut-off of 0.44 ng/ml. Using AFP ≥ 20 IU/ml or MDK ≥ 0.44 ng/ml, a significantly greater number (76.7%; n = 66/86) of HCC cases were detected. The area under the receiver operating curve for MDK was superior to AFP and OPN in NASH-HCC diagnosis. In the longitudinal cohort, MDK was elevated in 15/28 (54%) of HCC patients at diagnosis, of whom 67% had elevated MDK 6 months prior.

CONCLUSION

AFP and MDK have a complementary role in HCC detection. MDK increases the diagnostic yield in AFP-negative HCC and has greater diagnostic performance than AFP, OPN and DKK-1 in the diagnosis of NASH-HCC. Additionally, MDK has a promising role in the pre-clinical diagnosis of HCC.

Synergistic Effects of Combining Anti-Midkine and Hepatocyte Growth Factor Therapies Against Diabetic Nephropathy in Rats

PURPOSE

This study aimed to assess whether synergism could be achieved when combining midkine (MK) antisense oligodeoxynucleotides (anti-MK ODN) and recombinant human hepatocyte growth factor (HGF) in diabetic nephropathy (DN) rat models.

METHODS

Rats were randomized into 6 groups: control, DN rats without treatment, DN rats treated with scrambled ODN, DN rats treated with anti-MK ODN, DN rats treated with HGF and DN rats treated with anti-MK ODN plus HGF. DN models were created by intraperitoneal injection of streptozotocin. Two weeks later, treatments commenced. ODN (1 mg/kg) was intravenously injected weekly for 4 weeks. HGF (500 μg/kg) was subcutaneously injected daily for 4 weeks. Eight weeks later, rats were euthanized. Serum and urine parameters, kidney histopathological injury scores, immunohistochemistry and protein expressions were measured.

RESULTS

Blood glucose, creatinine, blood urea nitrogen and urine albumin were significantly elevated in DN rats. Any single treatment markedly reduced their levels, yet combined treatment decreased them significantly further. Any monotherapy could decrease renal injury score and immunohistochemistry positive percentage, although the most prominent change was displayed in combinational therapy. Western blot showed the expression of MK was significantly elevated in DN rats. Anti-MK ODN suppressed MK significantly. The protein expressions and serum concentrations of transforming growth factor-β1 and connective tissue growth factor between monotherapy and the combined therapy were significant.

CONCLUSIONS

This study demonstrated that combining MK gene suppressing ODN and HGF protein synergistically attenuates renal injury in DN rats. This study may provide a novel avenue for designing future therapeutic regimens against DN.

Evaluation of serum midkine as a biomarker in differentiated thyroid cancer

AIMS

Midkine is a multifunctional cytokine identified to be a promising cancer biomarker. We aimed to prospectively investigate serum midkine as a diagnostic and prognostic biomarker in differentiated thyroid cancer (DTC).

MAIN METHODS

162 patients with thyroid nodules participated in the surgical cohort (post-surgical pathology proved 70 cases with DTC and 92 cases with benign thyroid nodules), 75 healthy subjects served as control. Diagnostic values of pre-surgical midkine and thyroglobulin for DTC were conducted by receiver operating characteristic (ROC) curves. 214 DTC patients participated in the (131)I treatment cohort. Prognostic values of pre-(131)I-ablative midkine and thyroglobulin to predict (131)I-avid metastases were performed by ROC curves. Metastasis-free survival was analyzed by the Kaplan-Meier method.

KEY FINDINGS

Much better diagnostic capability of midkine than thyroglobulin was shown to differentiate DTC from benign thyroid nodules, with cut-off midkine value of 323.12pg/ml and diagnostic accuracy of 75.31%. Nearly similar diagnostic capabilities of midkine and thyroglobulin were shown to distinguish DTC from normal participants. Pre-(131)I-ablative thyroglobulin demonstrated perfect ability to predict metastases, with cut-off value and diagnostic accuracy of 19.50ng/ml and 96.73%. Midkine also performed well with a cut-off value and diagnostic accuracy of 504.71pg/ml and 89.25%. DTC patients with midkine or thyroglobulin levels higher than those of thresholds (500pg/ml or 20ng/ml) showed a significantly worse (131)I-avid metastasis-free survival by the Kaplan-Meier method (P<0.01).

SIGNIFICANCE

Our results show that midkine is as good as or even better than thyroglobulin to screen patients with thyroid nodules for DTC before surgery, and to predict whether metastases exist before the first (131)I ablative therapy.

Midkine expression in high grade gliomas: Correlation of this novel marker with proliferation and survival in human gliomas

BACKGROUND

High-grade primary glioma have poor prognosis and predictive biomarkers is very important. Midkine (MDK), a heparin-binding growth factor, is important in regulating carcinogenesis, cell proliferation, mitogenesis, and angiogenesis. This study aimed to identify over-expression of MDK in gliomas and correlate this with clinical outcomes. The authors put forward their hypothesis correlating proliferation and poor survival with over-expression of this novel protein.

METHODS

Two datasets from Gene Expression Omnibus (GEO) included human data of 100 and 180 patients, respectively. The MDK expression, World Health Organization (WHO) pathological grade, sex, age, and survival time were identified for statistical analysis.

RESULTS

A search of the GEO profile revealed that MDK expression level was statistically greater in the WHO grade IV compared with grade II (P = 0.002), in grades III and IV compared with nontumor control (P = 0.044 and P < 0.001, respectively) after adjustments using the Bonferroni method. By the Kaplan-Meier survival curve, the high MDK expression group had poorer survival outcome (2.38-fold hazard, 95% confidence interval: 1.22-4.63) than the low MDK expression group after adjustments for WHO grade and age.

CONCLUSIONS

Taken together, there is a positive correlation between MDK expression and WHO grading of human gliomas. Moreover, MDK over-expression is significant correlated to poor survival outcome in high-grade, suggesting that MDK may be an important therapeutic target.