Elevated Midkine Serum Levels Are Associated with Long-Term Survival in Critically Ill Patients

Midkine (Mdk) is a multifunctional protein involved in inflammatory processes. Hence, circulating Mdk is increased in sepsis and has been previously suggested as a potential biomarker in these patients. The aim of this study was to elucidate the role of Mdk serum concentrations in critical illness and sepsis and to verify its value as a prognostic biomarker. Thus, we analyzed the Mdk serum concentrations of 192 critically ill patients on admission to the medical intensive care unit (ICU). While the serum levels of Mdk at admission were similar in septic and nonseptic critical illness (362 vs. 337 ng/L, p = 0.727), we found several interesting correlations of Mdk to laboratory and clinical markers associated with ischemia or hypoxia, e.g., to renal failure and hepatic injury. Mdk serum concentrations at admission did not differ between various causes of sepsis or other critical illness. Most noticeable, we observed upregulated Mdk serum concentrations at admission in patients surviving in the long-term, which was only seen in nonseptic critical illness but not in sepsis. Our study suggests a relevant role of Mdk in critically ill patients in general and highlights the possible protective features of Mdk in critical illness.

Synthesis and interaction with growth factors of sulfated oligosaccharides containing an anomeric fluorinated tail

Compounds that mimic the biological properties of glycosaminoglycans (GAGs) and can be more easily prepared than the native GAG oligosaccharides are highly demanded. Here, we present the synthesis of sulfated oligosaccharides displaying a perfluorinated aliphatic tag at the reducing end as GAG mimetics. The preparation of these molecules was greatly facilitated by the presence of the fluorinated tail since the reaction intermediates were isolated by simple fluorous solid-phase extraction. Fluorescence polarization competition assays indicated that the synthesized oligosaccharides interacted with two heparin-binding growth factors, midkine (MK) and FGF-2, showing higher binding affinities than the natural oligosaccharides, and can be therefore considered as useful GAG mimetics. Moreover, NMR experiments showed that the 3D structure of these compounds is similar to that of the native sequences, in terms of sugar ring and glycosidic linkage conformations. Finally, we also demonstrated that these derivatives are able to block the MK-stimulating effect on NIH3T3 cells growth.

Large-scale proximity extension assay reveals CSF midkine and DOPA decarboxylase as supportive diagnostic biomarkers for Parkinson's disease

BACKGROUND

There is a need for biomarkers to support an accurate diagnosis of Parkinson's disease (PD). Cerebrospinal fluid (CSF) has been a successful biofluid for finding neurodegenerative biomarkers, and modern highly sensitive multiplexing methods offer the possibility to perform discovery studies. Using a large-scale multiplex proximity extension assay (PEA) approach, we aimed to discover novel diagnostic protein biomarkers allowing accurate discrimination of PD from both controls and atypical Parkinsonian disorders (APD).

METHODS

CSF from patients with PD, corticobasal syndrome (CBS), progressive supranuclear palsy (PSP), multiple system atrophy and controls, were analysed with Olink PEA panels. Three cohorts were used in this study, comprising 192, 88 and 36 cases, respectively. All samples were run on the Cardiovascular II, Oncology II and Metabolism PEA panels.

RESULTS

Our analysis revealed that 26 and 39 proteins were differentially expressed in the CSF of test and validation PD cohorts, respectively, compared to controls. Among them, 6 proteins were changed in both cohorts. Midkine (MK) was increased in PD with the strongest effect size and results were validated with ELISA. Another most increased protein in PD, DOPA decarboxylase (DDC), which catalyses the decarboxylation of DOPA (L-3,4-dihydroxyphenylalanine) to dopamine, was strongly correlated with dopaminergic treatment. Moreover, Kallikrein 10 was specifically changed in APD compared with both PD and controls, but unchanged between PD and controls. Wnt inhibitory factor 1 was consistently downregulated in CBS and PSP patients in two independent cohorts.

CONCLUSIONS

Using the large-scale PEA approach, we have identified potential novel PD diagnostic biomarkers, most notably MK and DDC, in the CSF of PD patients.

Evaluation of serum midkine levels and metabolic parameters in patients with hidradenitis suppurativa

The exact pathogenesis of Hidradenitis suppurativa (HS) has not been known yet. Midkine (MK) is a heparin-binding protein that has crucial roles in many processes such as cell proliferation, cell survival, cell migration, anti-apoptotic activity, and also inflammation and angiogenesis. No data exists in the literature on the evaluation of MK in patients with HS. The present study aimed to determine the serum levels of MK and metabolic parameters in patients with HS and to compare them with healthy subjects. Forty-five patients with HS and 45 healthy controls were included. The severity of the disease was assessed with Hurley staging system in the patient group. Levels of MK, C-reactive protein (CRP), lipids, and fasting glucose were measured with the enzyme-linked immunosorbent assay (ELISA) method. MK levels were significantly higher in the patient group (p < 0.05). Moreover, smoking habit, total cholesterol, triglyceride (TG), low-density lipoprotein (LDL) and CRP were significantly higher in the patient group (for all p < 0.05). Correlation analyses revealed that MK value was correlated positively with waist circumference, TG, total cholesterol level and diastolic blood pressure (for all p < 0.05), while negatively correlated with high-density lipoprotein (HDL) level (p = 0.046, r = - 0.219). There was no difference in the MK levels according to the severity of the disease among patients. This is the first preliminary study showing that these patients with HS have higher serum MK levels, which may also be related to autoinflammation, angiogenesis, atherosclerosis and metabolic syndrome risk.

Endothelin Receptor-A Inhibition Decreases Ductular Reaction, Liver Fibrosis, and Angiogenesis in a Model of Cholangitis

BACKGROUND & AIMS

Primary sclerosing cholangitis (PSC) leads to ductular reaction and fibrosis and is complicated by vascular dysfunction. Cholangiocyte and endothelial cell crosstalk modulates their proliferation in cholestatic models. Endothelin (ET)-1 and ET-2 bind to their receptor, ET-A, and cholangiocytes are a key source of ET-1 after bile duct ligation. We aimed to evaluate the therapeutic potential of ET-A inhibition in PSC and biliary-endothelial crosstalk mediated by this pathway.

METHODS

Wild-type and multidrug resistance 2 knockout (Mdr2-/-) mice at 12 weeks of age were treated with vehicle or Ambrisentan (ET-A antagonist) for 1 week by daily intraperitoneal injections. Human control and PSC samples were used.

RESULTS

Mdr2-/- mice at 4, 8, and 12 weeks displayed angiogenesis that peaked at 12 weeks. Mdr2-/- mice at 12 weeks had enhanced biliary ET-1/ET-2/ET-A expression and secretion, whereas human PSC had enhanced ET-1/ET-A expression and secretion. Ambrisentan reduced biliary damage, immune cell infiltration, and fibrosis in Mdr2-/- mice. Mdr2-/- mice had squamous cholangiocytes with blunted microvilli and dilated arterioles lacking cilia; however, Ambrisentan reversed these alterations. Ambrisentan decreased cholangiocyte expression of pro-angiogenic factors, specifically midkine, through the regulation of cFOS. In vitro, ET-1/ET-A caused cholangiocyte senescence, endothelial cell angiogenesis, and macrophage inflammation. In vitro, human PSC cholangiocyte supernatants increased endothelial cell migration, which was blocked with Ambrisentan treatment.

CONCLUSIONS

ET-A inhibition reduced biliary and liver damage in Mdr2-/- mice. ET-A promotes biliary angiocrine signaling that may, in turn, enhance angiogenesis. Targeting ET-A may prove therapeutic for PSC, specifically patients displaying vascular dysfunction.

Implication of the PTN/RPTPβ/ζ Signaling Pathway in Acute Ethanol Neuroinflammation in Both Sexes: A Comparative Study with LPS

Binge drinking during adolescence increases the risk of alcohol use disorder, possibly by involving alterations of neuroimmune responses. Pleiotrophin (PTN) is a cytokine that inhibits Receptor Protein Tyrosine Phosphatase (RPTP) β/ζ. PTN and MY10, an RPTPβ/ζ pharmacological inhibitor, modulate ethanol behavioral and microglial responses in adult mice. Now, to study the contribution of endogenous PTN and the implication of its receptor RPTPβ/ζ in the neuroinflammatory response in the prefrontal cortex (PFC) after acute ethanol exposure in adolescence, we used MY10 (60 mg/kg) treatment and mice with transgenic PTN overexpression in the brain. Cytokine levels by X-MAP technology and gene expression of neuroinflammatory markers were determined 18 h after ethanol administration (6 g/kg) and compared with determinations performed 18 h after LPS administration (5 g/kg). Our data indicate that Ccl2, Il6, and Tnfa play important roles as mediators of PTN modulatory actions on the effects of ethanol in the adolescent PFC. The data suggest PTN and RPTPβ/ζ as targets to differentially modulate neuroinflammation in different contexts. In this regard, we identified for the first time important sex differences that affect the ability of the PTN/RPTPβ/ζ signaling pathway to modulate ethanol and LPS actions in the adolescent mouse brain.

Can maternal serum midkine level predict chorionicity in twin pregnancies?

Sometimes it can be difficult to chorionicity determination in twin pregnancies. This study aimed to compare maternal serum midkine levels between twin and singleton pregnancies. We also evaluated the relationship between chorionicity and maternal serum midkine level in twin pregnancies. The present prospective cohort study included 16 patients with monochorionic diamniotic twin pregnancies, 38 with dichorionic diamniotic twin pregnancies, and 66 healthy singleton pregnancies admitted to Ankara City Hospital Perinatology Clinic between June 2021 and June 2022. Demographic features, clinical characteristics, and serum midkine levels were compared between the groups. Additionally, a receiver operator characteristics (ROC) analysis was performed to assess the performance of midkine for detecting chorionicity. The median maternal serum midkine level was found to be 0.64 ng/ml in twin pregnancies and 0.26 ng/ml in singleton pregnancies (p < 0.001). When twin pregnancies were compared in terms of chorionicity, serum midkine level was determined as 1.20 ng/ml in the monochorionic diamniotic group and 0.50 ng/ml in the dichorionic diamniotic group (p = 0.034). An optimal cut-off value of 1.03 ng/ml was found for the determination of chorionicity (AUC: 0.68, p = 0.03, 95% CI: 0.53-0.83, %56.3 sensitivity, 76.3% specificity). In advanced weeks of pregnancy, biomarkers can be used as helpful parameters for ultrasonography in the diagnosis of twin pregnancies. Maternal serum midkine levels might be used to determine chorionicity in equivocal cases.

Intercellular crosstalk in adult dental pulp is mediated by heparin-binding growth factors Pleiotrophin and Midkine

BACKGROUND

In-depth knowledge of the cellular and molecular composition of dental pulp (DP) and the crosstalk between DP cells that drive tissue homeostasis are not well understood. To address these questions, we performed a comparative analysis of publicly available single-cell transcriptomes of healthy adult human DP to 5 other reference tissues: peripheral blood mononuclear cells, bone marrow, adipose tissue, lung, and skin.

RESULTS

Our analysis revealed that DP resident cells have a unique gene expression profile when compared to the reference tissues, and that DP fibroblasts are the main cell type contributing to this expression profile. Genes coding for pleiotrophin (PTN) and midkine (MDK), homologous heparin-binding growth-factors, possessed the highest differential expression levels in DP fibroblasts. In addition, we identified extensive crosstalk between DP fibroblasts and several other DP resident cells, including Schwann cells, mesenchymal stem cells and odontoblasts, mediated by PTN and MDK.

CONCLUSIONS

DP fibroblasts emerge as unappreciated players in DP homeostasis, mainly through their crosstalk with glial cells. These findings suggest that fibroblast-derived growth factors possess major regulatory functions and thus have a potential role as dental therapeutic targets.

Evaluation of Midkine levels in pregnant women with preterm premature rupture of membranes: A cohort study from a tertiary hospital

OBJECTIVE

To assess midkine (MK) levels in pregnant women with preterm premature rupture of membranes (PPROM) and compare them to healthy pregnant women. We also assessed the performance of the maternal serum MK level in predicting neonatal intensive care unit (NICU) requirement in the PPROM group.

METHODS

Forty pregnant women who presented to our clinic at 24-37 gestational weeks and were diagnosed with PPROM were included in the study group. During the same period, 40 healthy pregnant women at similar gestational weeks were randomly selected as the control group. Clinical characteristics, inflammatory markers, and serum MK levels were compared between the groups. The same parameters were then compared between the PPROM cases with and without NICU requirement. Finally, the receiver operating characteristic (ROC) analysis was performed to assess the predictive value of MK for NICU requirement.

RESULTS

The PPROM and control groups were similar in terms of demographics. The MK level of the pregnant woman with PPROM was significantly higher than that of the controls. No statistically significant difference was found between the MK levels of the cases with and without NICU requirement in the PPROM group. In the ROC analysis, the optimal cut-off value of was found to be 0.287, at which it had 63 % sensitivity and 65 % specificity (area under the curve(AUC): 0.78, 95 % confidence interval(CI): 0.683-0.881, p < 0.001) for the prediction of NICU requirement in cases with PPROM. In the same analysis performed for the prediction of PPROM, when the optimal cut-off value was taken as 0.298, MK had 56 % sensitivity and 60 % specificity (AUC: 0.65, 95 % CI: 0.522-0.770, p = 0.037).

CONCLUSION

Serum MK seems to be associated with complicated inflammatory processes leading to PPROM, and this novel marker has the potential to predict NICU requirement in PPROM cases.

Cancer-associated fibroblasts facilitate DNA damage repair by promoting the glycolysis in non-small cell lung cancer

Radiotherapy is an essential treatment modality for the management of non-small cell lung cancer (NSCLC) patients. Tumor radioresistance is the major factor limiting the efficacy of radiotherapy in NSCLC patients. Our study aimed to reveal whether cancer-associated fibroblasts (CAFs), one main component of the tumor microenvironment, regulated DNA damage response of NSCLC cells following irradiation and clarify the involved mechanisms. We found CAFs inhibited irradiation-induced DNA damage while promoted DNA repair of NSCLC cells and caused cell cycle arrest in the radioresistant S phase. CAFs have the ability of up-regulating and stabilizing c-Myc, leading to the transcription activation of HK2 kinase, a key rate-limiting enzyme in glycolysis by activating Wnt/β-catenin pathway. Attenuation of glycolysis significantly reversed the effect of CAFs on DNA damage response of NSCLC cells. By high-throughput screening of human cytokines/chemokines array, we found CAFs-secreted midkine led to the promotion of glycolysis by activating Wnt/β-catenin pathway in NSCLC cells. In vivo, CAFs caused the radioresistance of NSCLC cells also by promoting the glycolysis in a β-catenin signaling-dependent manner. These findings may provide novel strategies for reversing the radioresistance of NSCLC cells.

Midkine mediates dysfunction of liver sinusoidal endothelial cells through integrin α4 and α6

Midkine (MK)² is an important regulatory molecule that promotes pathological angiogenesis of hepatocellular carcinoma (HCC). Although some studies have shown that its expression is increased in chronic liver disease, its effect on sinusoidal vasculopathy are still unclear. In this study, we demonstrated that MK was mainly secreted by liver sinus endothelial cells (LSECs) during the stage of precancerous lesions. Increased expression of its receptor integrin was an important mechanism by which MK participated in sinusoidal vasculopathy through autocrine and positive feedback effects. LSECs with high expression of integrin α6 (Itgα6⁺) and integrin α4 (Itgα4⁺) were used to study the mechanism of MK, and it was found that the effect of MK on LSECs was closely related to the integrin subtypes. The activation of MK /integrin α6/Src/Shc signaling pathway promoted the expression of ET-1, TXA2 and reduced the production of NO, and then induced the capillary vascularization of liver sinusoids, while the activation of MK/integrin α4/NF-κB pathway mainly induced angiogenesis by promoting the production of VEGF and Ang2. In the three-dimensional co-culture system of hepatocytes (BRL-3A) and LSECs, MK significantly increased the production of reactive oxygen species (ROS) in the co-culture system of highly expressed integrin LSECs and decreased the expression of tumor suppressor gene P53 in hepatocytes. These results suggested that MK /integrin signaling pathway, especially MK /integrin α6, was an important mechanism leaded to persistent sinusoidal hepatic vasculopathy in chronic liver disease and induced HCC，while MK/integrin α 4 activation was more involved in pathological angiogenesis.

Elevated serum midkine levels in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infected patients

BACKGROUND

The coronavirus disease-2019 (COVID-19) pandemic has caused important health, economic, social, and cultural problems worldwide. Recent findings demonstrate an excessive cytokine release during the disease development, especially in the seriously life-threatening form of COVID-19. Among other chemokines and cytokines that are released in high amounts at the infection site of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), midkine (MK), which is a potent pro-inflammatory growth factor/ cytokine, can be also overexpressed and contribute to the pathophysiological process in patients infected with SARS-CoV-2.

MATERIALS AND METHOD

Serum was collected from 87 intensive care unit (ICU) patients that are COVID-19 positive and 50 healthy volunteers in the control group with a negative PCR test and without disease symptoms. Circulating MK concentration was measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

COVID-19 patients had a significantly higher serum MK concentration compared to non-COVID-19 control subjects (1892.8 ± 1615.8 pg/mL versus 680.7 ± 907.6 pg/mL, respectively; P < 0.001). The cut-off MK concentration was 716.7 pg/ mL, with the sensitivity and specificity of 75.9 % and 76.0 %, respectively. The area under the receiver operating characteristic (ROC) curve of MK was = 0.827. Our findings showed that circulating MK levels are significantly increased in SARS-CoV-2 infected patients.

CONCLUSION

We suggest that MK is involved in the pathogenesis of COVID-19 and may be a part of hypercytokinaemia. Therefore, MK may serve as a supporting biomarker in the diagnosis of COVID-19, and blocking MK actions or its targets may attenuate the inflammatory process and the severity of the disease.

Identification and validation of a poor clinical outcome subtype of primary prostate cancer with Midkine abundance

Recent studies identified Midkine (MDK) as playing a key role in immune regulation. In this study, we aimed to discover the clinical significance and translational relevance in prostate cancer (PCa). We retrospectively analyzed 759 PCa patients who underwent radical prostatectomy from Huashan Hospital, Fudan University (training cohort, n = 369) and Chinese Prostate Cancer Consortium (validation cohort, n = 390). A total of 325 PCa patients from The Cancer Genome Atlas (TCGA) database (external cohort) were analyzed for exploration. Immune landscape and antitumor immunity were assessed through immunohistochemistry and flow cytometry. Patient‐derived explant culture system was applied for evaluating the targeting potential of MDK. We found that intratumoral MDK expression correlated with PCa progression, which indicated an unfavorable biochemical recurrence (BCR)‐free survival for postoperative PCa patients. Addition of MDK expression to the postoperative risk assessment tool CAPRA‐S could improve its prognostic value. Tumors with MDK abundance characterized the tumor‐infiltrating CD8⁺ T cells with less cytotoxicity production and increased immune checkpoint expression, which were accompanied by enriched immunosuppressive contexture. Moreover, MDK inhibition could reactivate CD8⁺ T cell antitumor immunity. MDK mRNA expression negatively correlated with androgen receptor activity signature and positively associated with radiotherapy‐related signature. In conclusion, intratumoral MDK expression could serve as an independent prognosticator for BCR in postoperative PCa patients. MDK expression impaired the antitumor function of CD8⁺ T cells through orchestrating an immunoevasive microenvironment, which could be reversed by MDK inhibition. Moreover, tumors with MDK enrichment possessed potential sensitivity to postoperative radiotherapy while resistance to adjuvant hormonal therapy of PCa. MDK could be considered as a potential therapeutic target for PCa.

Targeting of midkine alleviates cardiac hypertrophy via attenuation of oxidative stress and autophagy

Midkine levels are related to various diseases, including cardiovascular disease, renal disease and autoimmune disease. The research aimed to investigate the mitigation influence of downregulation of intermediate factors on myocardial hypertrophy induced by angiotensin Ⅱ (Ang), and whether downregulation of midkine could attenuate oxidative stress and autophagy. Induced myocardial hypertrophy of the mice model and treated HL-1 cells with Ang Ⅱ in vitro. The expressions of midkine were increased in the model and HL-1 cells with Ang II treatment. Midkine silence alleviated cardiac hypertrophy induced by Ang II, and inhibited the increases of atrial natriuretic peptide (ANP), Brain natriuretic peptide (BNP) and beta-myosin heavy chain (β-MHC) in the heart of mice. The raises of ANP, BNP and β-MHC in Ang II-induced HL-1 cells were also suppressed after midkine downregulation. Downregulating of midkine inhibited the increases of oxidative stress markers 8-OHdG, superoxide anions and MDA in the heart of mice or in the Ang II-treated HL-1 cells. The raises of LC3B, Atg3, Atg5 and Beclin1 in mice heart and in the Ang II.-induced HL-1 cells were attenuated after midkine silence. These outcomes showed that midkine was upregulated in myocardial hypertrophy mice. Targeting of midkine could alleviate cardiac hypertrophy via attenuation of oxidative stress and autophagy.

CAF-derived midkine promotes EMT and cisplatin resistance by upregulating lncRNA ST7-AS1 in gastric cancer

This study aimed to investigate the role of cancer-associated fibroblast (CAF)-derived midkine (MK) in cisplatin (DDP) resistance. The primary cultures of CAFs and non-cancer fibroblasts (NFs) were isolated and purified. The DDP-resistant gastric cancer (GC) cells were cultured with CAF-conditioned medium. QRT-PCR and Elisa assays were employed to determine MK expression. The expression of ST7-AS1 was measured by qRT-PCR. The impact of CAFs, MK, and ST7-AS1 silencing on DDP resistance was determined by MTT and Annexin V/PI staining assay. Expression of EMT markers and PI3K/AKT was determined by Western blot and qRT-PCR. The role of MK in DDP resistance was confirmed in a xenograft model. Incubation with CAF-conditioned medium increased the IC50 to DDP. Also, incubation with CAF-conditioned medium increased cell viability, reduced cell apoptosis, and promoted EMT in DDP-resistant GC cells, which were all blocked with MK neutralization antibody treatment. MK increased the DDP resistance and upregulated the expression of ST7-AS1 in DDP-resistant GC cells. Additionally, ST7-AS1 knockdown increased the sensitivity to DDP by inhibiting EMT. Moreover, ST7-AS1 knockdown significantly decreased the phosphorylation of PI3K and AKT, and suppressed EMT, which were restored by MK addition. Finally, MK promoted tumor growth and DDP resistance in a mice model bearing the SGC-7901/DDP xenografts. CAF-derived MK promotes EMT-mediated DDP resistance via upregulation of ST7-AS1 and activation of PI3K/AKT pathway.

Maternal serum midkine level increases in pregnant women with diabetes mellitus: a case-control study

OBJECTIVE

We aimed to compare maternal serum midkine level in pregnant women with different types of diabetes mellitus (DM) and healthy pregnant women. We also assessed maternal serum midkine level performance to predict adverse neonatal outcomes in the DM group.

METHODS

The study included 57 pregnant women diagnosed with gestational diabetes mellitus (GDM) and 41 pregnant women with preexisting DMThe control group consisted of 98 healthy pregnant women.

RESULTS

Serum midkine level is higher in the DM group than healthy ones (0.93 ± 0.8 vs. 0.23 ± 0.2, p<.001). When the diabetic groups were compared, the highest serum midkine level was found in GDM, followed by Type 1 DM and Type 2 DM (1.33 ± 0.9 ng/ml, 0.58 ± 0.5 ng/ml vs. 0.30 ± 0.2, respectively). Maternal serum midkine level was higher in the DM group with adverse perinatal outcomes than those without adverse outcomes, but there was no statistical difference (0.97 ± 0.91vs. 0.87 ± 0.73, p=.571).

CONCLUSIONS

Serum midkine level was significantly higher in pregnant women with GDM, Type 1, and 2 DM than healthy ones. Serum midkine level did not predict adverse neonatal outcomes in the DM group.

Midkine release during hemodialysis is predictive of hypervolemia and associates with excess (cardiovascular) mortality in patients with end-stage renal disease: a prospective study

Background

In end-stage renal disease, a high cardiovascular risk profile and endothelial damage prevails. The heparin-binding growth factor midkine stimulates neo-angiogenesis in ischemic diseases, coordinates neutrophil influx, and raises blood pressure through stimulated angiotensin synthesis.

Methods

We determined changes of midkine serum levels during hemodialysis sessions under the assumption that endothelial cell-derived midkine is released. Periprocedural differences (∆midkine) were calculated and correlated with cardiovacular biomarkers and fluid status (clinical assessment, V. cava collapse, comet tail phenomenon), cardiovascular morbidities, mortality rates. Blood was collected before and after dialysis from hemodialysis patients (n = 171; diabetes: n = 70; hypervolemia: n = 83; both: n = 32).

Results

Baseline midkine levels were ~ fourfold elevated compared to healthy controls (n = 100). Further, on average a tenfold rise was detected during dialysis, the extent of which was partially related to non-fractionated heparin application (r² = 0.17). Inter-individual differences were highly reproducible. Hypervolemic patients responded with a less than average rise in midkine levels during dialysis (p < 0.02), this difference became more obvious with co-existing diabetes (p < 0.001 for long dialysis-free interval) and was confirmed in an independently enrolled dialysis cohort (n = 88). In Kaplan Meier survival curves, low delta midkine levels correlated with cardiovascular/overall mortality rates, similar to elevated uPAR levels, whereas other markers (NTproANP, galectin, tenascin-C) were less predictive. Following intervention with successful fluid removal in hypervolemic dialysis patients to optimize fluid homeostasis, midkine values increased (p < 0.002), which was not observed in patients that failed to decrease weight.

Conclusion

Thus, for dialysis patients inadequate periprocedural midkine upregulation is linked with hypervolemia and associates with cardiovascular events.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11255-022-03141-4.

Insulin-Like Growth Factor 1 Receptor Drives Hepatocellular Carcinoma Growth and Invasion by Activating Stat3-Midkine-Stat3 Loop

BACKGROUND

Activation of the insulin-like growth factor 1 receptor (IGF-1R)-mediated Janus kinase (JAK)1/2-Stat3 pathway contributes to hepatocarcinogenesis. Specifically, a previous study showed that IGF-1R inhibition downregulated Midkine expression in hepatocellular carcinoma (HCC).

AIMS

The present study investigated the role of IGF-1R-JAK1/2-Stat3 and Midkine signaling in HCC, in addition to the molecular link between the IGF-1R-Stat3 pathway and Midkine.

METHODS

The expression levels of IGF-1R, Stat3, and Midkine were measured using reverse transcription-quantitative PCR, following which the association of IGF-1R with Stat3 and Midkine expression was evaluated in HCC. The molecular link between the IGF-1R-Stat3 pathway and Midkine was then investigated in vitro before the effect of IGF-1R-Stat3 and Midkine signaling on HCC growth and invasion was studied in vitro and in vivo.

RESULTS

IGF-1R, Stat3, and Midkine mRNA overexpressions were all found in HCC, where the levels of Stat3 and Midkine mRNA correlated positively with those of IGF-1R. In addition, Midkine mRNA level also correlated positively with Stat3 mRNA expression in HCC tissues. IGF-1R promoted Stat3 activation, which in turn led to the upregulation of Midkine expression in Huh7 cells. Similarly, Midkine also promoted Stat3 activation through potentiating JAK1/2 phosphorylation. Persistent activation of this Stat3-Midkine-Stat3 positive feedback signal loop promoted HCC growth and invasion, the inhibition of which resulted in significant antitumor activities both in vitro and in vivo.

CONCLUSIONS

Constitutive activation of the IGF-1R-mediated Stat3-Midkine-Stat3 positive feedback loop is present in HCC, the inhibition of which can serve as a potential therapeutic intervention strategy for HCC.

Midkine promotes breast cancer cell proliferation and migration by upregulating NR3C1 expression and activating the NF-κB pathway

BACKGROUND

Breast cancer (BC) is the most common malignancy in females and is the second leading cause of cancer-related death among women worldwide. Midkine (MDK) is a heparin-binding growth factor that is abnormally expressed at high levels in various human malignancies. We aimed to uncover the biological function and molecular mechanism of MDK in BC cells.

METHODS AND RESULTS

MDA-MB-231-shMDK and T47D-shMDK BC cells were established. The in vitro biological functions of MDK were demonstrated by CCK-8 assays, Transwell assays and Western blotting, whereas qPCR pathway arrays were implemented to explore the mechanism of MDK in BC cells. Functionally, we verified that silencing MDK significantly suppressed BC cell proliferation and migration by inhibiting the activation of the nuclear factor kappa B (NF-κB) pathway and the nuclear distribution of NF-κB. Meanwhile, Ingenuity Pathway Analysis (IPA) and a qPCR pathway array revealed that silencing MDK decreased the expression of NR3C1, a potential downstream target of the NF-κB pathway. We also confirmed that treatment with an NF-κB inhibitor suppressed NR3C1 expression in BC cells. Finally, we demonstrated that silencing NR3C1 repressed BC cell proliferation and migration.

CONCLUSIONS

Our findings highlight a novel mechanism by which MDK influences BC progression via regulation of the NF-κB-NR3C1 pathway.

The Serum Level of Midkine in Patients With Multiple Sclerosis and Neuromyelitis Optica

Introduction

Midkine (MK), a heparin-binding growth factor, is involved in neurological diseases by mediating the inflammatory responses through enhancing the leukocyte migration. The present study assesses the serum concentration of this growth factor among newly developed Multiple Sclerosis (MS) and Neuromyelitis Optica (NMO) patients.

Methods

The present research, as a cross-sectional study, was performed at Isfahan University of Medical Sciences, Isfahan City, Iran. All samples were selected from patients who visited Kashani and Alzahra hospitals for two years (2014 to 2016). The MK level was assessed in 80 new MS cases, 80 NMO patients, and 80 healthy subjects. After collecting blood sera samples, MK serum level was measured using the ELISA. The obtained data were analyzed in SPSS.

Results

The Mean±SD MK level was 1038.58±44.73 pg/mL in the MS group, which was significantly higher than the Mean±SD MK level in the NMO (872.62±55.42 pg/mL) and control groups (605.02±9.42 pg/mL).

Conclusion

Overall, these results demonstrated that MK plays a prominent role in inflammatory reactions and neuroautoimmune diseases, especially in MS. So, the MK level may be used for earlier diagnosis and also prevention of disease progression by using a special inhibitor.

Blood and urinary cytokine balance and renal outcomes at cardiac surgery

BACKGROUND

Increased perioperative pro-inflammatory biomarkers, renal hypoperfusion and ischemia reperfusion injury (IRI) heighten cardiac surgery acute kidney injury (CS-AKI) risk. Increased urinary anti-inflammatory cytokines attenuate risk. We evaluated whether blood and urinary anti-inflammatory biomarkers, when expressed as ratios with biomarkers of inflammation, hypoperfusion and IRI are increased in CS-AKI patients.

METHODS

Preoperative and 24-h postoperative blood and urinary pro-inflammatory and anti-inflammatory cytokines, blood VEGF and H-FABP (hypoperfusion biomarkers), and MK, a biomarker for IRI, were measured in 401 cardiac surgery patients. Pre- and postoperative concentrations of biomarkers and selected ratios thereof, were compared between non-CS-AKI and CS-AKI patients.

RESULTS

Compared with non-CS-AKI, blood pro-inflammatory (pre- and post-op TNFα, IP-10, IL-12p40, MIP-1α, NGAL; pre-op IL-6; post-op IL-8, MK) and anti-inflammatory (pre- and post-op sTNFsr1, sTNFsr2, IL-1RA) biomarkers together with urinary pro-inflammatory (pre- and post-op uIL-12p40; post-op uIP-10, uNGAL) and anti-inflammatory (pre- and post-op usTNFsr1, usTNFsr2, uIL-1RA) biomarkers, were significantly higher in CS-AKI patients. Urinary anti-inflammatory biomarkers, when expressed as ratios with biomarkers of inflammation (blood and urine), hypoperfusion (blood H-FABP and VEGF) and IRI (blood MK) were decreased in CS-AKI. In contrast, blood anti-inflammatory biomarkers expressed as similar ratios with blood biomarkers were increased in CS-AKI.

CONCLUSIONS

The urinary anti-inflammatory response may protect against the injurious effects of perioperative inflammation, hypoperfusion and IRI. These finding may have clinical utility in bioprediction and earlier diagnosis of CS-AKI and informing future therapeutic strategies for CS-AKI patients.

Extracellular vesicles derived from pancreatic cancer cells are enriched in the growth factor Midkine

The growth factor Midkine is a heparin-binding cytokine originally discovered during the differentiation process induced by the retinoic acid in embryonal carcinoma cells. Several studies pointed out the key role of this protein in tumour progression and its elevated expression in different malignancies, including pancreatic cancer. New diagnostic and therapeutic tools are urgently required to treat this highly aggressive and incurable disease capable of metastasising, evading diagnosis, and resisting therapy. Serum midkine promises to be a very functional tumour marker and a target for cancer treatment as an elevated concentration of serum midkine is consistently reported in patients with various tumours. Here, we identified high levels of midkine in extracellular vesicles isolated from pancreatic cancer cell lines and showed that it stimulates the growth of pancreatic cancer cells not expressing midkine.

Serum midkine levels for the diagnosis and assessment of response to interventional therapy in patients with hepatocellular carcinoma

Objective

To explore the clinical significance of serum midkine (MDK) levels for the diagnosis of hepatocellular carcinoma (HCC) and evaluate the efficacy of interventional therapy.

Methods

Eighty-four patients with HCC were enrolled in this retrospective study. They received an interventional treatment. A follow-up was performed every 2 months, using magnetic resonance imaging, to determine whether the treatment should be continued. Serum alpha-fetoprotein (AFP) and MDK levels were measured at the first diagnosis and during the follow-ups, and the HCC detection rates based on the cutoff values of these two measurements were compared. The relationships between AFP and MDK and the clinical tumor characteristics and changes in APK and MDK before and after treatment were also compared using a rank sum test and χ² test, respectively. The prognostic significance of MDK for HCC was determined through regression analysis. A two-sided P ​< ​0.05 was considered statistically significant.

Results

MDK expression was detected in 95.24% of the cases. Subgroup analysis revealed MDK expression in 95.35%, 95.12%, 85.19%, 86.67%, and 83.33% of the AFP-positive, AFP-negative, stage A Barcelona clinic liver cancer (BCLC-A), BCLC-A/AFP-positive, and BCLC-A/AFP-negative cases, respectively. MDK expression after the interventional treatment (66.7%) was significantly lower than that before the treatment (95.2%). The mean post-treatment MDK level was 0.67 ​ng/mL in patients with a positive response to therapy as compared with 3.66 ​ng/mL in those with no positive response. All patients were followed up for 18 months, and those positive for MDK expression before the intervention were more likely to relapse than patients without MDK expression. Subgroup analysis revealed the highest recurrence rate for patients who were positive for MDK expression before and after treatment.

Conclusions

Serum MDK may serve as a powerful complement to AFP in the diagnosis of HCC. MDK measurement may improve the detection rate of BCLC-A and AFP-negative HCC. Serum MDK may help to determine the vascular invasion and poor clinical staging of HCC tumors. Patients with MDK-positive HCC before treatment may be more prone to postoperative tumor progression.

Efficient drug delivery by novel cell-penetrating peptide derived from Midkine, with two heparin binding sites braced by a length-specific helix

Cell-penetrating peptides (CPPs) have been regarded as potential drug carriers for cancer therapy. However, most well-studied CPPs fail to deliver exogenous drugs efficiently and selectively. In this study, a tumour-targeted CPP with high efficiency derived from heparin-binding domain (HBD) of Midkine (named HMD) was discovered. HMD exhibited higher delivery efficiency than classic CPPs (TAT and R9) and manifested selectivity in tumour cells. Normally, the positive charge is the key factor for the transmembrane activity of CPPs such as TAT and R9. Here, the length of α-helix inside CPP was found also important for in the recognition of heparan sulphate proteoglycans (HSPGs). Subsequently, the introduction of HMD enhanced the inhibitory effect of Momordica antiviral protein of 30 kDa (MAP30) on tumour cells, resulting in a 6.07-fold and 5.42-fold increase in HeLa cells and MGC80-3 cells respectively without enhanced cytotoxicity in normal cells. These results show that HMD possesses high efficiency and good tumour specificity and can be utilised as a promising agent for the tumour-targeted delivery of drug. This study is also a supplement to the existing theories about the biological activities of the α-helix in CPPs.

Serum midkine level might be a diagnostic tool for COVID19 disease in pregnancy: From the disease severity, hospitalization and disease progression respects

BACKGROUND

New biomarkers for diagnosis and monitoring the COVID-19 disease are the most important topics to be studied recently. We aimed to investigate the association between midkine levels and disease severity in pregnant women with COVID-19.

METHODS

Totally 186 pregnant women were participated in this study. 96 of them were healthy pregnant women, 90 of them were pregnant women with COVID19. Pregnant women were evaluated according to their trimesters. Serum midkine level, biochemical profile clinical and disease severity outcomes of pregnant women were obtained.

RESULTS

Our results showed that pregnant women with COVID19 have significantly increased serum midkine level compared to healthy pregnant women (1.801 ± 0.977 vs 0.815 ± 0.294 ng/dL). According to the data among each trimester, it was shown that there were significant increase in serum midkine level during all pregnancy trimesters (1st trimester Control Group: 0.714 ± 0.148, COVID-19 group 1.623 ± 0.824, p < 0.0001; 2nd trimester Control Group: 0.731 ± 0.261, COVID-19 group 2.059 ± 1.146, p < 0.0001; 3rd trimester Control Group: 1.0 ± 0.35, COVID-19 group 1.723 ± 0.907, p = 0.001). Serum midkine levels were significantly different between disease severity subgroups of pregnant women with COVID19; moderate and severe/critic groups had significantly higher serum midkine level than mild group. There was also significant correlation between serum midkine level and severity status (p:0.0001, r: 0.468). The most striking results of serum midkine levels were corelation between length of hospitalization (p: 0.01, r: 0.430) and O² saturation (p < 0.0001, r: -0.521). ROC curve analysis showed that serum midkine level might be a tool for predicting COVID-19 in pregnant women with COVID-19 (AUC: 0.912, 95% CI: [0.871, 0.952], p < 0.0001) CONCLUSION: Our data showed that there is an obvious relation between COVID19 progression and serum midkine level for the first time which might be used for monitoring the disease process.

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.

Midkine promotes glioblastoma progression via PI3K-Akt signaling

Background

Our previous bioinformatics-based study found that midkine (MDK) was associated with poor prognosis of glioblastoma (GBM). However, the mechanism of MDK in GBM remains elusive.

Methods

A public GBM-related dataset and GBM tissues from our center were used validate the aberrant expression of MDK in GBM at the RNA and protein levels. The relationship between MDK expression and survival of GBM patients was also explored through survival analysis. Subsequently, we identified MDK-related GBM-specific genes using differential expression analysis. Functional enrichment analyses were performed to reveal their potential biological functions. CCK-8, 5-ethynyl-2′-deoxyuridine, and Matrigel-transwell assays were performed in GBM cell lines in which MDK was knocked out or overexpressed in order assess the effects of MDK on proliferation, migration, and invasion of GBM cells. Western blotting was performed to detect candidate proteins.

Results

Our study showed MDK is a promising diagnostic and prognostic biomarker for GBM because it is highly expressed in the disease and it is associated with poor prognosis. MDK is involved in various cancer-related pathways, such as PI3K-Akt signaling, the cell cycle, and VEGF signaling. A comprehensive transcriptional regulatory network was constructed to show the potential pathways through which MDK may be involved in GBM. In vitro, Overexpression of MDK augmented proliferation, migration, and invasion of GBM cell lines, whereas suppression of MDK led to the opposite effects. Furthermore, our study confirmed that MDK promotes the progression of GBM by activating the PI3K-Akt signaling pathway.

Conclusions

Our present study proposes that MDK promotes GBM by activating the PI3K-Akt signaling pathway, and it describes a potential regulatory network involved.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02212-3.

Midkine and chronic kidney disease-associated multisystem organ dysfunctions

Chronic kidney disease (CKD) is a progressive multisystem condition with yet undefined mechanistic drivers and multiple implicated soluble factors. If identified, these factors could be targeted for therapeutic intervention for a disease that currently lacks specific treatment. There is increasing preclinical evidence that the heparin/endothelial glycocalyx-binding molecule midkine (MK) has a pathological role in multiple CKD-related, organ-specific disease processes, including CKD progression, hypertension, vascular and cardiac disease, bone disease and CKD-related cancers. Concurrent with this are studies documenting increases in circulating and urine MK proportional to glomerular filtration rate (GFR) loss in CKD patients and evidence that administering soluble MK reverses the protective effects of MK deficiency in experimental kidney disease. This review summarizes the growing body of evidence supporting MK's potential role in driving CKD-related multisystem disease, including MK's relationship with the endothelial glycocalyx, the deranged MK levels and glycocalyx profile in CKD patients and a proposed model of MK organ interplay in CKD disease processes and highlights the importance of ongoing research into MK's potential as a therapeutic target.

Midkine: Utility as a Predictor of Early Diabetic Nephropathy in Children with Type 1 Diabetes Mellitus

Objective

This study aimed to assess the role of serum midkine (MK) as a biomarker for early detection of diabetic nephropathy in children with type 1 diabetes mellitus (T1DM) before microalbuminuria emerges.

Methods

A total of 120 children with T1DM, comprising 60 microalbuminuric patients (Group 1), 60 normoalbuminuric patients (Group 2), and 60 healthy participants as a control group (Group 3) were included. Detailed medical history, clinical examination, and laboratory assessment of high-sensitivity C-reactive protein (hs-CRP), hemoglobin A1c percentage (HbA1c%), lipid profile, urinary albumin to creatinine ratio (ACR), serum MK and estimated glomerular filtration rate based on serum creatinine were performed in all participants.

Results

Both Group 1 and Group 2 had significantly higher serum MK compared to controls (p<0.001). Additionally, significantly higher MK concentrations were present in Group 1 compared with Group 2 (p<0.001). Receiver operating characteristic curve analysis revealed that the MK concentration cutoff value of 1512 pg/mL was able to predict microalbuminuria with a sensitivity of 96% and specificity of 92%. Stepwise regression analysis revealed that HbA1c%, hs-CRP, and ACR were independently related to MK levels (p<0.001 for each).

Conclusion

The results of this study suggest that serum MK is a useful, novel, practical marker for the evaluation of renal involvement in children with T1DM, especially in normoalbuminuric children.

Midkine: A multifaceted driver of atherosclerosis

Atherosclerosis constitutes the pathological basis of life-threatening events, including heart attack and stroke. Midkine is a heparin-binding growth factor and forms a small protein family with pleiotrophin. Under inflammatory or hypoxic conditions, midkine expression is up-regulated. Upon binding to its receptors, midkine can activate multiple signal pathways to regulate cell survival and migration, epithelial-to-mesenchymal transition, and oncogenesis. Circulating midkine levels are significantly increased in patients with essential hypertension, obesity or severe peripheral artery disease. Importantly, midkine exerts a proatherogenic effect by altering multiple pathophysiological processes involving atherogenesis, including macrophage lipid accumulation, vascular inflammation, neointima formation, insulin resistance and macrophage apoptosis. Midkine represents a potential therapeutic target for atherosclerosis-associated diseases. This review described the structure characteristics, expression patterns and signal transduction pathways of midkine with an emphasis on its role in atherosclerosis.

Shedding more light on the role of Midkine in hepatocellular carcinoma: New perspectives on diagnosis and therapy

One of the most common malignant tumors is hepatocellular carcinoma (HCC). Progression of HCC mainly results from highly complex molecular and pathological pathways. Midkine (MDK) is a growth factor that impacts viability, migration, and other cell activities. Since MDK has been involved in the inflammatory responses, it has been claimed that MDK has a crucial role in HCC. MDK acts as an anti-apoptotic factor, which mediates tumor cell viability. In addition, MDK blocks anoikis to promote metastasis. There is also evidence that MDK is involved in angiogenesis. It has been shown that the application of anti-MDK approaches might be promising in the treatment of HCC. Besides, due to the elevated expression in HCC, MDK has been proposed as a biomarker in the prognosis and diagnosis of HCC. In this review, we will discuss the role of MDK in HCC. It is hoped that the development of new strategies concerning MDK-based therapies will be promising in HCC management.

Pulmonary midkine inhibition ameliorates sepsis induced lung injury

Background

Midkine is a multi-functional molecule participating in a various key pathological process. We aimed to evaluate the change of midkine in sepsis and its association with angiotensin-converting enzyme (ACE) system, as well as the mechanism by which midkine induced in sepsis and lung injury.

Methods

The peripheral blood sample of septic patients on admission was obtained and measured for midkine, ACE and angiotensin II. Cecal ligation and puncture (CLP) mouse model was used, and adeno-associated virus (AAV) was stilled trans-trachea for regional targeting midkine expression, comparing the severity of lung injury. Furthermore, we studied the in vitro mechanism of midkine activates ACE system by using inhibitors targeting candidate receptors of midkine, and its effects on the vascular endothelial cells.

Results

Plasma midkine was significantly elevated in sepsis, and was closely associated with ACE system. Both circulating and lung midkine was increased in CLP mouse, and was related to severe lung injury. Regional interfering midkine expression in lung tissue by AAV could alleviate acute lung injury in CLP model. In vitro study elucidated that Notch 2 participated in the activation of ACE system and angiotensin II release, induced by midkine and triggered vascular endothelial injury by angiotensin II induced reactive oxygen species production.

Conclusions

Midkine inhibition ameliorates sepsis induced lung injury, which might via ACE/Ang II pathway and the participation of Notch 2 in the stimulation of ACE.

Trial registration

Clinicaltrials.gov NCT02605681. Registered 12 November 2015

Ultra-small lipid nanoparticles encapsulating sorafenib and midkine-siRNA selectively-eradicate sorafenib-resistant hepatocellular carcinoma in vivo

Hepatocellular carcinoma (HCC) is a fatal disease with limited therapeutic choices. The stroma-rich tumor microenvironment hinders the in vivo delivery of most nanomedicines. Ultra-small lipid nanoparticles (usLNPs) were designed for the selective co-delivery of the cytotoxic drug, sorafenib (SOR), and siRNA against the Midkine gene (MK-siRNA) to HCC in mice. The usLNPs composed of a novel pH-sensitive lipid, a diversity of phospholipids and a highly-selective targeting peptide. A microfluidic device, iLiNP, was used and a variety of factors were controlled to tune particle size aiming at maximizing tumor penetration efficiency. Optimizing the composition and physico-chemical properties of the usLNPs resulted in an enhanced tumor accumulation, selectivity and in vivo gene silencing. The optimized usLNPs exerted potent gene silencing in the tumor (median effective dose, ED₅₀~0.1 mg/Kg) with limited effect on the healthy liver. The novel combination synergistically-eradicated HCC in mice (~85%) at a surprisingly-low dose of SOR (2.5 mg/Kg) which could not be achieved via individual monotherapy. Toxicity studies revealed the biosafety of the usLNPs upon either acute or chronic treatment. Furthermore, the SOR-resistant HCC established in mice was eradicated by 70% using this approach. We conclude that our strategy is promising for potential clinical applications in HCC treatment.

Multiple pathophysiological roles of midkine in human disease

Midkine (MK) is a low molecular-weight protein that was first identified as the product of a retinoic acid-responsive gene involved in embryonic development. Recent studies have indicated that MK levels are related to various diseases, including cardiovascular disease (CVD), renal disease and autoimmune disease. MK is a growth factor involved in multiple pathophysiological processes, such as inflammation, the repair of damaged tissues and cancer. The pathophysiological roles of MK are diverse. MK enhances the recruitment and migration of inflammatory cells upon inflammation directly and also through induction of chemokines, and contributes to tissue damage. In lung endothelial cells, oxidative stress increased the expression of MK, which induced angiotensin-converting enzyme (ACE) expression and the consequent conversion from Ang I to Ang II, leading to further oxidative stress. MK inhibited cholesterol efflux from macrophages by reducing ATP-binding cassette transporter A1 (ABCA1) expression, which is involved in lipid metabolism, suggesting that MK is an important positive factor involved in inflammation, oxidative stress and lipid metabolism. Furthermore, MK can regulate the expansion, differentiation and activation of T cells as well as B-cell survival; mediate angiogenic and antibacterial activity; and possess anti-apoptotic activity. In this paper, we summarize the pathophysiological roles of MK in human disease.

Oncolytic effect of Midkine promoter-based conditionally replicating adenoviruses expressing EGFR siRNA in head and neck squamous cancer cell line T891

Background

Epidermal growth factor receptor (EGFR) is overexpressed in head and neck squamous cell carcinomas (HNSCCs). Midkine expression is restricted in adult tissues but is increased in several malignant tumors, including HNSCCs.

Aim

Here, we evaluated the antitumor effect of Midkine promoter–based conditionally replicative adenovirus expressing siRNA against EGFR for targeting HNSCCs expressing Midkine.

Methods and results

A conditionally replicative adenovirus vector controlled by the Midkine promoter, Ad‐MK‐siEGFR, was generated by integrating gene‐expressing siRNA against EGFR. Antitumor effect of Ad‐MK‐siEGFR was tested in vitro using established HNSCC cell line, T891 with strong Midkine expression. Expression of EGFR in T891 infected with Ad‐MK‐siEGFR was significantly lower than that of T891 infected with control. Cytotoxicity assays showed significant growth suppression of Ad‐MK‐siEGFR in T891 cells.

Conclusions

This study demonstrated the possibility of oncolytic therapy using the Midkine promoter–based conditional replication‐selective adenovirus containing siRNA against EGFR in HNSCC cell line T891. Further validation of the findings in more cell lines and in vivo should be performed to clarify the potential clinical application.

Midkine level may be used as a noninvasive biomarker in Crohn’s disease

Background/aim

Crohn’s disease (CD) is a kind of inflammatory bowel disease. Midkine (MDK) is an endogenous inflammatory marker. We aimed to investigate the relationship between MDK levels and inflammation and hence determine whether MDK can be used as a noninvasive biomarker in active CD.

Materials and methods

Sixty-five consecutive patients over the age of 18 with CD and 36 healthy controls were included in this study. CD patients’ venous blood samples were taken before treatment. Serum MDK levels were determined in human plasma samples by enzyme-linked immunosorbent assay (ELISA) method.

Results

The mean age of the study patients was 44.8 ± 12.5 years, 35 patients were female, and 30 were male. Of these 65 patients, 37 had active CD and 28 were in the remission phase. MDK levels were significantly higher in active and remission CD than in healthy controls (P = 0.01, P = 0.038, respectively).

Conclusion

We report that there is an association between MDK levels and CD activation, and therefore with enhanced inflammation. MDK levels were significantly correlated with inflammatory indices. In line with our findings, we suggest the theory that MDK inhibitors may be useful in treating Crohn’s disease.

Midkine signaling maintains the self-renewal and tumorigenic capacity of glioma initiating cells

Glioblastoma (GBM) is one of the most aggressive forms of cancer. It has been proposed that the presence within these tumors of a population of cells with stem-like features termed Glioma Initiating Cells (GICs) is responsible for the relapses that take place in the patients with this disease. Targeting this cell population is therefore an issue of great therapeutic interest in neuro-oncology. We had previously found that the neurotrophic factor MIDKINE (MDK) promotes resistance to glioma cell death. The main objective of this work is therefore investigating the role of MDK in the regulation of GICs.

Methods: Assays of gene and protein expression, self-renewal capacity, autophagy and apoptosis in cultures of GICs derived from GBM samples subjected to different treatments. Analysis of the growth of GICs-derived xenografts generated in mice upon blockade of the MDK and its receptor the ALK receptor tyrosine kinase (ALK) upon exposure to different treatments.

Results: Genetic or pharmacological inhibition of MDK or ALK decreases the self-renewal and tumorigenic capacity of GICs via the autophagic degradation of the transcription factor SOX9. Blockade of the MDK/ALK axis in combination with temozolomide depletes the population of GICs in vitro and has a potent anticancer activity in xenografts derived from GICs.

Conclusions: The MDK/ALK axis regulates the self-renewal capacity of GICs by controlling the autophagic degradation of the transcription factor SOX9. Inhibition of the MDK/ALK axis may be a therapeutic strategy to target GICs in GBM patients.

Inhibition of Receptor Protein Tyrosine Phosphatase β/ζ Reduces Alcohol Intake in Rats

BACKGROUND

Pleiotrophin (PTN) and midkine (MK) are cytokines that are up-regulated in the prefrontal cortex (PFC) after alcohol administration and have been shown to reduce alcohol intake and reward. Both cytokines are endogenous inhibitors of receptor protein tyrosine phosphatase (RPTP) β/ζ (a.k.a. PTPRZ1). Recently, a new compound named MY10 was designed with the aim of mimicking the activity of PTN and MK. MY10 has already shown promising results regulating alcohol-related behaviors in mice.

METHODS

We have now tested the effects of MY10 on alcohol operant self-administration and Drinking In the Dark-Multiple Scheduled Access (DID-MSA) paradigms in rats. Gene expression of relevant genes in the PTN/MK signaling pathway in the PFC was analyzed by real-time PCR.

RESULTS

MY10, at the highest dose tested (100 mg/kg), reduced alcohol consumption in the alcohol operant self-administration paradigm (p = 0.040). In the DID-MSA paradigm, rats drank significantly less alcohol (p = 0.019) and showed a significant decrease in alcohol preference (p = 0.002). We observed that the longer the exposure to alcohol, the greater the suppressing effects of MY10 on alcohol consumption. It was demonstrated that the effects of MY10 were specific to alcohol since saccharin intake was not affected by MY10 (p = 0.804). MY10 prevented the alcohol-induced down-regulation of Ptprz1 (p = 0.004) and anaplastic lymphoma kinase (Alk; p = 0.013) expression.

CONCLUSIONS

Our results support and provide further evidence regarding the efficacy of MY10 on alcohol-related behaviors and suggest the consideration of the blockade of RPTPβ/ζ as a target for reducing excessive alcohol consumption.

Urinary Biomarkers may Complement the Cleveland Score for Prediction of Adverse Kidney Events After Cardiac Surgery: A Pilot Study

Background

The ability of urinary biomarkers to complement established clinical risk prediction models for postoperative adverse kidney events is unclear. We assessed the effect of urinary biomarkers linked to suspected pathogenesis of cardiac surgery-induced acute kidney injury (AKI) on the performance of the Cleveland Score, a risk assessment model for postoperative adverse kidney events.

Methods

This pilot study included 100 patients who underwent open-heart surgery. We determined improvements to the Cleveland Score when adding urinary biomarkers measured using clinical laboratory platforms (neutrophil gelatinase-associated lipocalin [NGAL], interleukin-6) and those in the preclinical stage (hepcidin-25, midkine, alpha-1 microglobulin), all sampled immediately post-surgery. The primary endpoint was major adverse kidney events (MAKE), and the secondary endpoint was AKI. We performed ROC curve analysis, assessed baseline model performance (odds ratios [OR], 95% CI), and carried out statistical reclassification analyses to assess model improvement.

Results

NGAL (OR [95% CI] per 20 concentration-units wherever applicable): (1.07 [1.01–1.14]), Interleukin-6 (1.51 [1.01–2.26]), midkine (1.01 [1.00–1.02]), 1-hepcidin-25 (1.08 [1.00–1.17]), and NGAL/hepcidin-ratio (2.91 [1.30–6.49]) were independent predictors of MAKE and AKI (1.38 [1.03–1.85], 1.08 [1.01–1.15], 1.01 [1.00–1.02], 1.09 [1.01–1.18], and 3.45 [1.54–7.72]). Category-free net reclassification improvement identified interleukin-6 as a model-improving biomarker for MAKE and NGAL for AKI. However, only NGAL/hepcidin-25 improved model performance for event- and event-free patients for MAKE and AKI.

Conclusions

NGAL and interleukin-6 measured immediately post cardiac surgery may complement the Cleveland Score. The combination of biomarkers with hepcidin-25 may further improve diagnostic discrimination.

Pharmacokinetics of midkine with different N-terminal structures in rats

Midkine (MK) is a heparin-binding growth factor that functions in multiple physiological processes, making it a promising drug target for treating various diseases including osteoarthritis (OA). However, the lack of pharmacokinetic studies on MK limits further clinical research. As the N-domain of MK protein appears to be more important for its stability, this study aimed to investigate the pharmacokinetic profiles of recombinant human (rh)MK with different structures at the N-terminus via different administration routes in rats and guinea pigs. A single intramuscular (IM) injection of 1 mg/kg rhMK with or without extended sequences at the N-terminus expressed by E. coli or Pichia was administered to six male SD rats. rhMK concentrations in sequential tail blood samples were measured by ELISA. rhMK without extended N-terminal sequences expressed by Pichia had a greater area under the curve (AUC), slower clearance, and longer half-life in rats following a single IM injection than those of the other rhMK proteins. The AUC values for rhMK after IM and intra-articular (IA) administration were 1523.3 ± 35.2 h × ng/mL and 872.0 ± 36.1 h × ng/mL, whereas the apparent volumes of distribution (Vd/f) were 0.184 ± 0.067 L/kg and 11.6 ± 0.8 L/kg, respectively, suggesting that rhMK was distributed more locally after IA injection than after IM injection as Vd/f magnitude gives a general idea of extent distribution in the body and higher Vd/f represents more locally distribution. rhMK concentration in the articular cartilage was markedly higher than that in serum and reached the highest level at 3 days after a single IA injection in Hartley guinea pigs. As the dose increased from 10 to 50 mg/kg, the AUC increased in a greater-than-dose-proportional manner, suggesting that rhMK exhibits non-linear pharmacokinetics in rats after a single IM injection in this dose range. These results indicated that the N-terminal structure and administration route have substantial effects on the pharmacokinetics of rhMK in rats. Furthermore, rhMK was maintained in articular cartilage with minimal diffusion into the blood following IA injection in Hartley guinea pigs, providing a foundation for clinical research on the use of rhMK for OA treatment via IA delivery.

Heparin Administration, but Not Myocardial Ischemia or Necrosis, Leads to Midkine Elevation

Midkine (MK) is a heparin-binding growth factor, whose role as a biomarker of coronary artery disease, myocardial ischaemia and necrosis has not been well measured. This study quantified serial MK levels in patients undergoing coronary angiography (CA) and identified factors associated with MK. In this single-centre, parallel cohort study, forty patients undergoing CA had arterial samples collected prior, 10 and 20 min after heparin administration. Four groups were examined: 1-stable coronary artery disease (CAD) without percutaneous coronary intervention (PCI); 2-stable CAD for elective PCI; 3-non-ST elevation myocardial infarction (NSTEMI) with or without PCI; 4-ST elevation myocardial infarction (STEMI) with primary PCI. Groups 1, 2 and 4 were heparin naïve, allowing assessment of the effects of myocardial necrosis between baseline levels; group 3 had received low-molecular-weight heparin. MK levels were analysed by ELISA. Median MK at baseline did not differ between groups, demonstrating that myocardial ischaemia or necrosis does not affect MK levels. Heparin administration had an immediate effect on median MK at 10 min, showing an average 500-fold increase that is dose-dependent (R² = 0.35, p = 0.001). Median MK levels remained elevated at 20 min following heparin administration. Multivariate analysis showed that the estimated glomerular filtration rate (eGFR) was the only predictor of elevated baseline MK (p = 0.02). Baseline MK did not correlate with high-sensitivity troponin-I (HsTnI) taken just before CA (p = 0.97), or peak HsTnI during admission (p = 0.74). MK is not a reliable marker of myocardial ischaemia or necrosis. MK increased significantly in all patients following heparin administration in a dose-dependent manner.

Disruption of Midkine gene reduces traumatic brain injury through the modulation of neuroinflammation

Background

Midkine (MK) is a multifunctional cytokine found upregulated in the brain in the presence of different disorders characterized by neuroinflammation, including neurodegenerative disorders and ischemia. The neuroinflammatory response to traumatic brain injury (TBI) represents a key secondary injury factor that can result in further neuronal injury. In the present study, we investigated the role of endogenous MK in secondary injury, including neuroinflammation, immune response, and neuronal apoptosis activity, after TBI.

Methods

Wild type (Mdk^+/+) and MK gene deficient (Mdk^−/−) mice were subjected to fluid percussion injury for TBI models and compared at 3, 7, and 14 days after TBI, in terms of the following: brain tissue loss, neurological deficits, microglia response, astrocytosis, expression of proinflammatory M1 and anti-inflammatory M2 microglia/macrophage phenotype markers, and apoptotic activity.

Results

As opposed to Mdk^+/+ mice, Mdk^−/− mice reported a significantly reduced area of brain tissue loss and an improvement in their neurological deficits. The ratios of the Iba1-immunoreactive microglia/macrophages in the perilesional site were significantly decreased in Mdk^−/− than in the Mdk^+/+ mice at 3 days after TBI. However, the ratios of the glial fibrillary acidic protein immunoreactive area were similar between the two groups. The M1 phenotype marker (CD16/32) immunoreactive areas were significantly reduced in Mdk^−/− than in the Mdk^+/+ mice. Likewise, the mRNA levels of the M1 phenotype markers (TNF-α, CD11b) were significantly decreased in Mdk^−/− mice than in Mdk^+/+ mice. Furthermore, flow cytometry analysis identified the M2 markers, i.e., CD163⁺ macrophages cells and arginase-1⁺ microglia cells, to be significantly higher in Mdk^−/− than in Mdk^+/+ mice. Finally, the ratios of apoptotic neurons were significantly decreased in the area surrounding the lesion in Mdk^−/− than in Mdk^+/+ mice following TBI.

Conclusion

Our findings suggest that MK-deficiency reduced tissue infiltration of microglia/macrophages and altered their polarization status thereby reducing neuroinflammation, neuronal apoptosis, and tissue loss and improving neurological outcomes after TBI. Therefore, targeting MK to modulate neuroinflammation may represent a potential therapeutic strategy for TBI management.

Serum Midkine is a clinical significant biomarker for colorectal cancer and associated with poor survival

Colorectal carcinoma (CRC) is one of the most common carcinomas worldwide. Early detection is crucial for reducing morbidity and mortality. Several promising studies described the use of midkine (MK) as a tumor marker. This study aimed to investigate a larger collective to ascertain if the preoperative serum midkine level (S‐MK) is suitable as a marker for screening and if S‐MK correlates with tumor progression and localization. It was also investigated for the first time whether patients with high S‐MK show poor survival. This prospective single‐center study included 299 patients with CRC. The preoperative serum midkine level (S‐MK) was determined using ELISA. Established tumor markers Carcinoembryonic antigen (CEA) and Carbohydrate antigen 19‐9 (CA 19‐9) were collected for comparison. The median follow‐up period was 65 months. S‐MK was significantly elevated in patients with CRC (P < .001). The receiver operation characteristic (ROC) curve has an area under the curve (AUC) of 0.868 (P < .001). A cut‐off value of 56.42 pg/mL results in a sensitivity of 84.3% and a specificity of 75.4%. In the one‐way analysis of variance (ANOVA), there were no significant correlations between S‐MK and tumor progression, localization. Furthermore, no significant correlation to CEA und CA 19‐9 could be found. Kaplan‐Meier survival analysis was able to show for the first time that patients with S‐MK of more than 225 pg/mL have a significantly shorter survival. Multivariate Cox regression showed that only CEA was an independent prognostic factor for survival. S‐MK helps estimate the prognosis for CRC and is a valuable component for developing a multimarker panel for screening and surveillance.

Midkine promotes articular chondrocyte proliferation through the MK-LRP1-nucleolin signaling pathway

Osteoarthritis (OA) is the most common disease of joint tissues; unfortunately, there are currently no curative therapies available for OA. Chondrocytes, the only cell type residing in cartilage, secrete many types of collagen (the mainly one is type II collagen) and aggrecan, which are the main components of the cartilage matrix. Chondrocyte apoptosis can lead to OA degenerative progression. We previously indicated that recombinant human midkine (rhMK), as a chondrocyte growth factor has a significant reparative effect on cartilage injury animal models. However, the molecular mechanism of this restorative function remains under investigation. Herein, we focused on the molecular mechanism underlying the role of MK in promoting the proliferation of chondrocytes cultured in vitro. Chondrocytes from rats and OA patients were successfully isolated by the digestion of articular cartilage using type II collagenase, and their proliferation was evaluated by a CCK8 assay and flow cytometry. rhMK stimulated the proliferation of chondrocytes from both OA patients and rats. Furthermore, qRT-PCR, shRNA-mediated knockdown, Western blot and immunoprecipitation (IP) assays were performed to identify the receptor and key elements responsible for the role of MK in promoting chondrocyte proliferation. Low-density lipoprotein receptor-related protein 1 (LRP1) was identified as the dominant MK receptor in chondrocytes that, as a translocator, mediates the endocytosis of MK. After being transferred into chondrocytes, MK was shown to form a complex with nucleolin that interacts with the active form of K-Ras. Upon the activation of ERK1/2, cyclin D1 expression was upregulated, promoting the chondrocyte cell cycle. Our data reveal for the first time the role of the MK-LRP1-nucleolin signaling pathway in facilitating MK-induced chondrocyte proliferation, thus providing a strong theoretical foundation for the further use of MK in OA clinical therapy.

Relationship between cachexia and perineural invasion in pancreatic adenocarcinoma

BACKGROUND

Cachexia is responsible for the low quality of life in pancreatic adenocarcinoma (PDAC). The rapid disease progression and patient deterioration seems related to perineural invasion, but the relationship between cachexia and perineural invasion for the evolution of the disease has been rarely studied. As perineural invasion is difficult to be highlighted, a biomarker such as the neurotrophic factor Midkine (MK) which promotes the neuronal differentiation and the cell migration could be helpful. Also, Activin (ACV) has been described as cachexia related to PDAC. However, their role for assessing and predicting the disease course in daily practice is not known.

AIM

To assess the relationship between perineural invasion and cachexia and their biomarkers, MK and ACV, respectively, and their prognostic value.

METHODS

This study included prospectively enrolled patients with proven adenocarcinoma and a matched group of controls without any malignancies. Patients with other causes of malnutrition were excluded. The plasma levels of ACV and MK were analyzed using western blotting and were correlated with the clinicopathological features and survival data. These results were validated by immunohistochemical analyses of the pancreatic tumor tissue of the patients included in the study and a supplementary group of surgically resected specimens from patients with a benign disease.

RESULTS

The study comprised 114 patients with PDAC, 125 controls and a supplementary group of 14 benign pancreatic tissue samples. ACV and MK were both overexpressed more frequently in the plasma of patients with PDAC than in the controls (63% vs 32% for ACV, P < 0.001; 47% vs 16% for MK, P < 0.001), with similar levels in pancreatic tissue the MK protein expression was closely related to the advanced clinical stage (P = 0.006), the presence of metastasis (P = 0.04), perineural invasion (P = 0.03) and diabetes (P = 0.002), but with no influence on survival. No correlation between clinicopathological factors and ACV expression was noted. Cachexia, present in 19% of patients, was unrelated to ACV or MK level. Higher ACV expression was associated with a shorter survival (P = 0.008).

CONCLUSION

The MK was a biomarker of perineural invasion, associated with tumor stage and diabetes, but without prognostic value as ACV. Cachexia was unrelated to perineural invasion, ACV level or survival.

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.

Diagnostic value of the serum Midkine in patients with rheumatoid arthritis

Early diagnosis and detection of rheumatoid arthritis (RA) activity which is a potential therapeutic target, depends mainly on clinical presentation. However, laboratory tests may contribute to diagnosis and disease activity assessment of RA. This study aims to evaluate the accuracy of serum Midkine as serological marker for RA diagnosis and its activity detection. All patients with RA were recruited during the period from January 2016 to August 2018 in addition to healthy subjects as control. Serum Midkine level was estimated using enzyme immunoassay. The accuracy was determined for serum Midkine against the used American College of Rheumatology/European League Against Rheumatism 2010 classification criteria for RA diagnosis and disease activity score derivative for 28 joints-erythrocyte sedimentation rate (ESR) score for assessment of RA disease activity. A total of 211 of patients with RA (group I) were enrolled in this study with 112 healthy subjects (group II). Patients with RA were divided into two subgroups according to the disease activity; patients with active RA (group IA) and RA in remission (group IB). We detected that the area under curve (AUC) of serum Midkine level (AUC=0.851) was significantly lower than that of rheumatoid factor IgM and anti-cyclic citrullinated peptide IgG for RA diagnosis. However, Midkine presents a significantly higher diagnostic accuracy (AUC=0.939) in detecting RA activity than that offered by C reactive protein (CRP) or ESR. Our study suggested that serum Midkine is a potential serological marker for detection of active inflammatory state with higher diagnostic accuracy than other inflammatory markers as CRP or ESR. Therefore, it can be used as an inflammatory marker for detection of disease activity rather than diagnosis of RA.

The effectiveness of serum midkine in detecting esophageal squamous cell carcinoma

BACKGROUND

Studies investigating serum midkine (s-MK) concentrations have employed a polyclonal antibody enzyme-linked immunosorbent assay system (ELISA), because the targeted polyclonal antibody has low specificity. We used a newly developed monoclonal antibody ELISA to investigate the prognostic and diagnostic capabilities of s-MK in patients with esophageal squamous cell carcinoma.

METHODS

Serum samples from 102 patients with esophageal squamous cell carcinoma were analyzed using a newly developed monoclonal antibody ELISA specifically developed to detect s-MK. s-MK cutoff value was set at 421 pg/mL (mean + 2 SD) based on data from healthy controls. Clinicopathological characteristics, including tumor stage and positivity rates for two conventional tumor markers, serum p53 (s-p53-Abs) antibodies and SCC-antigen, were evaluated to assess a possible correlation with s-MK. The prognostic capability of a high s-MK level was evaluated using univariate and multivariate methods.

RESULTS

Overall positive rate for s-MK concentrations: 21%. Large tumors (> 50 mm) showed significantly higher concentrations than smaller specimens, but other clinicopathological factors were not associated with s-MK. A combination assay using SCC-antigen together with s-p53-Abs and s-MK clearly increased our capability to detect esophageal squamous cell carcinoma. Although the difference was not statistically significant (P = 0.310), the high s-MK group experienced worse overall survival than our low s-MK group.

CONCLUSIONS

s-MK and conventional tumor marker combination increased our capability to detect esophageal squamous cell carcinoma. Although s-MK might be associated with esophageal squamous cell carcinoma progression, it was not an independent risk factor reducing patient survival. This study was registered as UMIN000014530.

Inhibition of RPTPβ/ζ blocks ethanol-induced conditioned place preference in pleiotrophin knockout mice

Pleiotrophin (PTN) and Midkine (MK) are neurotrophic factors that are upregulated in the prefrontal cortex after alcohol administration and have been shown to reduce ethanol drinking and reward. PTN and MK are endogenous inhibitors of Receptor Protein Tyrosine Phosphatase (RPTP) β/ζ. Interestingly, pharmacological inhibition of RPTPβ/ζ reduces ethanol consumption and blocks ethanol-induced conditioned place preference (CPP) in wild type mice. Since PTN-knockout (Ptn^-/-) mice are more sensitive to the conditioning effects of alcohol, we aimed to test the effects of MY10, a small-molecule inhibitor of RPTPβ/ζ, on ethanol-induced CPP in Ptn^-/- mice. The data presented here demonstrate for the first time that a regular dose of MY10, known to block ethanol consumption and reward in wild type mice, also blocks the rewarding effects of ethanol in the more vulnerable individuals lacking PTN, the endogenous inhibitor of RPTPβ/ζ. In addition, since MY10 readily penetrates the blood brain barrier (BBB), we tested its effects in a series of behavioural tests in Ptn^+/+ and Ptn^-/- mice. The data indicate that MY10 does not cause gross behavioural effects in wild type mice. However, MY10 tended to induce anxiolytic effects in Ptn^-/- mice in the elevated plus maze paradigm. Overall, the data indicate that MY10 rescues Ptn^-/- mice from their increased susceptibility to the conditioning effects of ethanol and may induce anxiolytic effects in individuals with reduced or absent PTN functions. Further studies are needed to confirm the potential of pharmacological inhibition of RPTPβ/ζ as a new therapeutic strategy in the treatment of anxiety-related disorders.

Expression of the heparin-binding growth factors Midkine and pleiotrophin during ocular development

Midkine (MDK) and Pleiotrophin (PTN) belong to a group of heparin-binding growth factors that has been shown to have pleiotropic functions in various biological processes during development and disease. Development of the vertebrate eye is a multistep process that involves coordinated interactions between neuronal and non-neuronal cells, but very little is known about the potential function of MDK and PTN in these processes. In this study, we demonstrate by section in situ hybridization, the spatiotemporal expression of MDK and PTN during ocular development in chick and mouse. We show that MDK and PTN are expressed in dynamic patterns that overlap in a few non-neuronal tissues in the anterior eye and in neuronal cell layers of the posterior eye. We show that the expression patterns of MDK and PTN are only conserved in a few tissues in chick and mouse but they overlap with the expression of some of their receptors LRP1, RPTPZ, ALK, NOTCH2, ITGβ1, SDC1, and SDC3. The dynamic expression patterns of MDK, PTN and their receptors suggest that they function together during the multistep process of ocular development and they may play important roles in cell proliferation, adhesion, and migration of neuronal and non-neuronal cells.