Co-localization of Protein Z, Protein Z-Dependent protease inhibitor and coagulation factor X in human colon cancer tissue: implications for coagulation regulation on tumor cells

F10 Gene Expression and Ethnic Disparities Present in Papillary Thyroid Carcinoma

Papillary thyroid carcinoma (PTC) presents a significant health concern, particularly among Hispanic women in the United States, who exhibit a disproportionately higher chance of developing an advanced disease when compared to the non-Hispanic population. Emerging evidence suggests coagulation factor X, encoded by the F10 gene, has a potential role in inhibiting cancer cell migration. However, comprehensive investigations into the differential expression patterns of F10 in Hispanic versus non-Hispanic females remain limited. RNA-sequencing data were acquired from the TCGA database for white female patients, 166 non-Hispanic and 25 Hispanic. A statistically significant (p < 0.05) 2.06-fold increase in F10 expression levels was detected in disease-free tumors compared to recurrent PTC tumors. Furthermore, an increase in F10 gene expression levels was also observed, corresponding to approximately a 1.74-fold increase in non-Hispanic patients compared to Hispanic patients. The probability of tumor recurrence was 1.82 times higher in the cohort with low expression of F10 compared to the high-expression cohort, correlating with the lower disease-free rates observed in the Hispanic patient cohort when compared to non-Hispanics. This finding underscores the relevance of ethnic disparities in molecular profiles for understanding cancer susceptibility. Identifying F10 as a potential prognostic biomarker highlights avenues for targeted interventions and contributes to improving diagnostic and treatment strategies for diverse patient populations.

Protein Z modulates the metastasis of lung adenocarcinoma cells

Protein Z (PZ), a vitamin-K-dependent anticoagulant glycoprotein, is reported to be highly expressed in various malignant tissues and correlated with a poor prognosis in patients with lung cancer. This study aimed to investigate the pathological activity of PZ on lung cancer cell migration, invasion, and metastasis. PZ was assessed by Western blot in three non-small-cell lung cancer cell lines (A549, H1299, and H1975). Meanwhile,western blot was used to detect the expression of EMT pathway-related proteins (Slug, Vimentin, and N-cadherin) in the A549 cells knocked down with siRNA. The cellular proliferation, migration, and invasion were detected by Cell Counting Kit (CCK)-8, wound healing, and Transwell assays in the A549 cells. The results showed that PZ expression was higher in A549, H1299, and H1975 cells, according to Western blot. CCK-8, wound healing, and Transwell assays showed that knockdown of PZ significantly decreased cellular proliferation, migration, and invasion, as well as the protein levels of Slug, Vimentin, and N-cadherin in the A549 cells. In conclusion, the pro-metastasis activity of PZ may modulate the epithelial-mesenchymal transition pathway in lung cancer A549 cells.

Impact of hereditary thrombophilia on cancer-associated thrombosis, tumour susceptibility and progression: A review of existing evidence

Venous thromboembolism (VTE) is a cardiovascular disorder frequently diagnosed among cancer patients. Aside from being common, VTE severely deteriorates the prognosis of these patients as they face a higher risk of morbidity and mortality, which makes clinical tools able to identify the patients more prompt to thrombogenesis very attractive. Over the years, several genetic polymorphisms have been linked with VTE susceptibility in the general population. However, their clinical usefulness as predictive biomarkers for cancer-related VTE is yet unclear. Furthermore, as a two-way association between cancer and VTE is well-recognized, with haemostatic components fuelling tumour progression, haemostatic gene polymorphisms constitute potential cancer predictive and/or prognostic biomarkers as well. Thus, in this article, we review the existing evidence on the role of these polymorphisms on cancer-related VTE and their impact on cancer onset and progression. Despite the promising findings, the existing studies had inconsistent results most likely due to their limited statistical power and population heterogeneity. Future studies are therefore required to clarify the role of these polymorphisms in setting of malignancy.

ZPI prevents ox-LDL-mediated endothelial injury leading to inhibition of EndMT, inflammation, apoptosis, and oxidative stress through activating Pi3k/Akt signal pathway

Oxidized low-density lipoprotein (ox-LDL)-mediated endothelial dysfunction exerts an essential role in the development of atherosclerosis. Protein Z-dependent protease inhibitor (ZPI), a member of the serine protease inhibitor superfamily, could inhibit the function of activated coagulation factor X (FXa) via interaction with protein Z (PZ). Studies have pointed out that ZPI was statistically related to atherosclerotic diseases, which may have a robust cardiovascular protective effect. However, the underlying mechanism of ZPI on ox-LDL-mediated endothelial injury requires further elucidation. Human umbilical vein endothelial cells (HUVECs) were treated with ox-LDL (100 μg/ml) and ZPI (10 μg/ml). Cell viability was measured by the Cell Counting Kit-8 (CCK-8) assay. Cell apoptosis, oxidative stress, and endothelial-to-mesenchymal transition (EndMT) were analyzed by immunofluorescence (IF). Cell migration was measured using a wound-healing assay. Quantitative real-time polymerase chain reaction and western blot analysis were performed to determine messenger RNA and protein expression. Ox-LDL (100 μg/ml, 48 h) significantly reduced cell viability and migration, increased EndMT, inflammation, apoptosis, and oxidative stress. The related protein expression of phosphatidylinositol 3 kinase/protein kinase B (Pi3k/Akt) signal pathway in HUVECs was also simultaneously decreased. We also discovered that ZPI treatment could prevent ox-LDL-mediated endothelial injury through the improvement of cell viability and alleviation of apoptosis, oxidative stress, EndMT, and inflammation. Thus, the protective effect of ZPI on HUVECs may be mediated by activation of the Pi3k/Akt signal pathway. ZPI may exert an important protective role in HUVECs dysfunction triggered by ox-LDL via activation of the Pi3k/Akt signal pathway. Therefore, ZPI may possess potential therapeutic effects on atherosclerotic endothelial injury-related diseases.

The Proteolytic Inactivation of Protein Z-Dependent Protease Inhibitor by Neutrophil Elastase Might Promote the Procoagulant Activity of Neutrophil Extracellular Traps in Sepsis

Septic shock is the archetypal clinical setting in which extensive crosstalk between inflammation and coagulation dysregulates the latter. The main anticoagulant systems are systematically impaired, depleted, and/or downregulated. Protein Z-dependent protease inhibitor (ZPI) is an anticoagulant serpin that not only targets coagulation factors Xa and XIa but also acts as an acute phase reactant whose plasma concentration rises in inflammatory settings. The objective of the present study was to assess the plasma ZPI antigen level in a cohort of patients suffering from septic shock with or without overt-disseminated intravascular coagulation (DIC). The plasma ZPI antigen level was approximately 2.5-fold higher in the patient group (n = 100; 38 with DIC and 62 without) than in healthy controls (n = 31). The elevation's magnitude did not appear to depend on the presence/absence of DIC. Furthermore, Western blots revealed the presence of cleaved ZPI in plasma from patients with severe sepsis, independently of the DIC status. In vitro, ZPI was proteolytically inactivated by purified neutrophil elastase (NE) and by NE on the surface of neutrophil extracellular traps (NETs). The electrophoretic pattern of ZPI after NE-catalyzed proteolysis was very similar to that resulting from the clotting process-suggesting that the cleaved ZPI observed in severe sepsis plasma is devoid of anticoagulant activity. Taken as a whole, our results (1) suggest that NE is involved in ZPI inactivation during sepsis, and (2) reveal a novel putative mechanism for the procoagulant activity of NETs in immunothrombosis.

Glioma stem cells activate platelets by plasma-independent thrombin production to promote glioblastoma tumorigenesis

Background

The interaction between platelets and cancer cells has been underexplored in solid tumor models that do not metastasize, for example, glioblastoma (GBM) where metastasis is rare. Histologically, it is known that glioma stem cells (GSCs) are found in perivascular and pseudsopalisading regions of GBM, which are also areas of platelet localization. High platelet counts have been associated with poor clinical outcomes in many cancers. While platelets are known to promote the progression of other tumors, mechanisms by which platelets influence GBM oncogenesis are unknown. Here, we aimed to understand how the bidirectional interaction between platelets and GSCs drives GBM oncogenesis.

Methods

Male and female NSG mice were transplanted with GSC lines and treated with antiplatelet and anti-thrombin inhibitors. Immunofluorescence, qPCR, and Western blots were used to determine expression of coagulation mechanism in GBM tissue and subsequent GSC lines.

Results

We show that GSCs activate platelets by endogenous production of all the factors of the intrinsic and extrinsic coagulation cascades in a plasma-independent manner. Therefore, GSCs produce thrombin resulting in platelet activation. We further demonstrate that the endogenous coagulation cascades of these cancer stem cells are tumorigenic: they activate platelets to promote stemness and proliferation in vitro and pharmacological inhibition delays tumor growth in vivo.

Conclusions

Our findings uncover a specific preferential relationship between platelets and GSCs that drive GBM malignancies and identify a therapeutically targetable novel interaction.

PROZ May Serve as a Prognostic Biomarker for Early Hepatocellular Carcinoma

Objective

The occurrence and development of hepatocellular carcinoma (HCC) remain unclear. This study aimed to investigate potential diagnostic or prognostic markers for early HCC by applying bioinformatic analysis.

Methods

The gene expression profiles of early HCC and normal tissues from a TCGA dataset were used to identify differentially expressed genes (DEGs) and then analysed by weighted gene coexpression network analysis. The integrated genes were selected to construct the protein–protein interaction (PPI) network and determine the hub genes. The prognostic impact of the hub genes was then analysed.

Results

A total of 508 integrated genes were selected from the 615 DEGs and 8956 genes in the turquoise module. A PPI network was constructed, and the top 20 hub genes, including apolipoprotein A-IV (APOA4), fibrinogen gamma chain (FGG), vitamin K-dependent protein Z (PROZ), secreted phosphoprotein 24 (SPP2) and fetuin-B (FETUB), were identified. Only PROZ was significantly associated with the prognosis of early HCC.

Conclusion

In this study, we demonstrated that the expression of PROZ was decreased in early HCC compared with normal liver controls, and low PROZ expression might result in poor overall survival of early HCC.

Insights into the Role of Tick Salivary Protease Inhibitors during Ectoparasite-Host Crosstalk

Protease inhibitors (PIs) are ubiquitous regulatory proteins present in all kingdoms. They play crucial tasks in controlling biological processes directed by proteases which, if not tightly regulated, can damage the host organism. PIs can be classified according to their targeted proteases or their mechanism of action. The functions of many PIs have now been characterized and are showing clinical relevance for the treatment of human diseases such as arthritis, hepatitis, cancer, AIDS, and cardiovascular diseases, amongst others. Other PIs have potential use in agriculture as insecticides, anti-fungal, and antibacterial agents. PIs from tick salivary glands are special due to their pharmacological properties and their high specificity, selectivity, and affinity to their target proteases at the tick-host interface. In this review, we discuss the structure and function of PIs in general and those PI superfamilies abundant in tick salivary glands to illustrate their possible practical applications. In doing so, we describe tick salivary PIs that are showing promise as drug candidates, highlighting the most promising ones tested in vivo and which are now progressing to preclinical and clinical trials.

Adenovirus Receptor Expression in Cancer and Its Multifaceted Role in Oncolytic Adenovirus Therapy

Oncolytic adenovirus therapy is believed to be a promising way to treat cancer patients. To be able to target tumor cells with an oncolytic adenovirus, expression of the adenovirus receptor on the tumor cell is essential. Different adenovirus types bind to different receptors on the cell, of which the expression can vary between tumor types. Pre-existing neutralizing immunity to human adenovirus species C type 5 (HAdV-C5) has hampered its therapeutic efficacy in clinical trials, hence several adenoviral vectors from different species are currently being developed as a means to evade pre-existing immunity. Therefore, knowledge on the expression of appropriate adenovirus receptors on tumor cells is important. This could aid in determining which tumor types would benefit most from treatment with a certain oncolytic adenovirus type. This review provides an overview of the known receptors for human adenoviruses and how their expression on tumor cells might be differentially regulated compared to healthy tissue, before and after standardized anticancer treatments. Mechanisms behind the up- or downregulation of adenovirus receptor expression are discussed, which could be used to find new targets for combination therapy to enhance the efficacy of oncolytic adenovirus therapy. Additionally, the utility of the adenovirus receptors in oncolytic virotherapy is examined, including their role in viral spread, which might even surpass their function as primary entry receptors. Finally, future directions are offered regarding the selection of adenovirus types to be used in oncolytic adenovirus therapy in the fight against cancer.

A Panel of Three Biomarkers Identified by iTRAQ for the Early Diagnosis of Pancreatic Cancer

PURPOSE

Due to a lack of early diagnostic markers, pancreatic cancer (PC) remains a lethal disease. Proteomic approaches are now being applied to identify novel PC biomarkers.

EXPERIMENTAL DESIGN

In this study, iTRAQ and LC-MS/MS are used to perform comparative analyses of serum from PC patients and healthy controls (HC), to identify specific serum biomarkers for PC. Serum levels of candidate proteins are determined using ELISA.

RESULTS

Among 869 proteins identified, 55 are potential biomarkers; Vitamin K-dependent protein Z (PROZ) and tumor necrosis factor receptor superfamily member 6b (TNFRSF6B) are selected for further analysis. Serum levels of PROZ and TNFRSF6B are significantly higher in PC patients than in HC or pancreatic benign controls (BC) (p < 0.01). The AUCs range from 0.816 to 0.971 for PROZ, TNFRSF6B, and carbohydrate antigen 19-9, either individually or in combination, in PC versus HC+BC, and from 0.711 to 0.932 in PC Stage I versus HC+BC.

CONCLUSIONS AND CLINICAL RELEVANCE

It is demonstrated that PROZ and TNFRSF6B are novel serum biomarkers for detecting early stage PC, and for distinguishing PC from pancreatic benign tumor and healthy individuals. Additional large cohort studies are needed to develop PROZ and TNFRSF6B as clinical PC biomarkers.

Co-localization of Coagulation Factor X and its Inhibitory System, PZ/ZPI, in Human Endometrial Cancer Tissue

BACKGROUND/AIM

Hemostatic system components contribute to cancer progression independently from their roles in hemostasis. It has been shown that protein Z (PZ)/protein Z-dependent protease inhibitor (ZPI) inhibit coagulation factor X (FX). The aim of the study was to analyze the expression of PZ/ZPI in relation to the main coagulation factor - FX in human endometrial cancer tissue.

MATERIALS AND METHODS

Immunohistochemical analysis was performed on 21 endometrial cancer specimens employing antibodies against ZPI, PZ and FX.

RESULTS

Endometrial cancer cells showed a strong expression of ZPI and PZ and medium expression of FX. Normal endometrial tissue showed no expression of ZPI, PZ or FX.

CONCLUSION

Strong expression of PZ and ZPI in endometrial cancer cells suggests a role of these proteins in endometrial cancer.

Soft fibrin matrix downregulates DAB2IP to promote Nanog-dependent growth of colon tumor-repopulating cells

Colon cancer stem cells (CSCs) have been shown to be responsible for the recurrence and metastasis of colorectal cancer (CRC). As a crucial microenvironmental factor, extracellular matrix (ECM) stiffness is known to affect the stemness of CSCs. Recently, fibrin deposition in the stroma of CRC was demonstrated to be responsible for tumor development. In this study, we used salmon fibrin gel to provide a 3D ECM for colon cancer cells and investigated its effects on cell growth as well as the underlying mechanisms. Compared with stiff 420 Pascal (Pa) and 1 050 Pa gels, 90 Pa soft fibrin gel was most efficient at isolating and enriching tumor colonies. The size and number of colony formation negatively correlated with gel stiffness. Specifically, these tumor colonies exhibited efficient tumorigenicity, upregulated stem cell markers, and had anti-chemotherapeutic properties and were thus named tumor-repopulating cells (TRCs). More importantly, the self-renewal molecule Nanog was sharply induced in 3D-cultured colon TRCs; further, Nanog siRNA significantly inhibited colony formation, suggesting the indispensable role of Nanog in TRC growth. A subsequent mechanistic study illustrated that Nanog expression could be modulated through fibrin gel stiffness-induced DAB2IP/PI3K/FOXA1 signaling in colon TRCs.

Subtype-specific clinical and prognostic relevance of tumor-expressed F5 and regulatory F5 variants in breast cancer: the CoCaV study

Essentials The role of coagulation factor V (encoded by F5) in cancer pathogenesis is unknown. The clinical significance of tumor-expressed F5 was evaluated in breast cancer patient cohorts. F5 was expressed in human breast tumors, and the expression was higher than in normal tissue. High F5 expression was associated with aggressive tumors, but also with survival in breast cancer.

SUMMARY

Background Tumor expression of certain coagulation factors has been linked to cancer progression. Single nucleotide polymorphisms (SNPs) in F5 (encoding the FV protein) have been found to be associated with breast cancer; however, the role of coagulation factor V (FV) in cancer pathogenesis remains undiscovered. Objectives We aimed to investigate the clinical significance of FV and the regulatory role of F5 gene variants in breast cancer. Patients/Methods A Scandinavian 503-sample breast cancer cohort and three public breast cancer datasets (GOBO, TCGA and KM plotter) were used to determine associations between F5 gene expression (tumor-specific), circulating FV, F5 SNPs, clinical characteristics and breast cancer survival. Immunohistochemistry (IHC) was used to detect FV antigen in tumors. Results F5 expression was 2-fold higher in breast tumors compared with normal tissue, and the presence of FV antigen in breast tumors was confirmed by IHC staining. F5 expression was increased in patients with hormone receptor negative tumors, triple negative tumors, HER2-enriched and basal-like tumors. In patients with basal tumors, high expression of F5 was associated with improved overall survival (hazard ratio, HR = 0.52, 95% confidence interval, 0.31-0.86). SNPs in F5 were associated with tumor size and luminal A tumors. The rs6427202-rs9332542 C-G haplotype, previously associated with breast cancer, displayed a cis-regulatory effect on F5 expression in tumors and plasma FV antigen levels. In silico mining supported this regulatory function. Conclusions FV was a possible marker of aggressive breast cancer, yet also a predictor of favorable outcome. Evaluation of FV expression may be clinically useful for prognosis and treatment decisions in aggressive breast cancer.

Low Protein Z levels in patients with plasma cell neoplasms are inversely correlated with IL-6 levels

Patients with multiple myeloma (MM) have an increased thrombotic risk, but pathogenesis remains uncertain. Low levels of Protein Z (PZ), a vitamin K-dependent plasma protein, are associated with venous as well as arterial thrombosis. The purpose of this study was to analyze PZ levels in patients with plasma cell neoplasms.

PATIENTS AND METHODS

The study consisted of 64 plasma cells neoplasm patients and 42 healthy individuals. Clinical investigations included measurement of plasma PZ and IL-6 levels.

RESULTS

PZ levels in patients with plasma cell neoplasms were significantly lower compared to healthy controls in the entire cohort (1392±659 vs.2010±603ng/mL, P<0.01), as well as in specific disease subgroups; symptomatic MM (1428±652ng/mL, p<0.01), smoldering MM (1437±883ng/mL, p=0.045) and monoclonal gammopathy of undetermined significance (MGUS) (1247±593ng/mL, p=0.01). PZ was negatively correlated with IL-6 levels in MM patients (r=-0.7, P<0.01). There was no significant difference in PZ levels between patients with or without thrombotic event.

CONCLUSION

Plasma cell neoplasm patients have low levels of PZ. This is presumably related to the increased IL-6 production by the bone marrow microenvironment, and could have a potential role in the increased thrombotic tendency in those patients.

Revisiting antithrombotic therapeutics; sculptin, a novel specific, competitive, reversible, scissile and tight binding inhibitor of thrombin

Thrombin is a multifunctional enzyme with a key role in the coagulation cascade. Its functional modulation can culminate into normal blood coagulation or thrombosis. Thus, the identification of novel potent inhibitors of thrombin are of immense importance. Sculptin is the first specific thrombin inhibitor identified in the transcriptomics analysis of tick’s salivary glands. It consists of 168 residues having four similar repeats and evolutionary diverged from hirudin. Sculptin is a competitive, specific and reversible inhibitor of thrombin with a K_i of 18.3 ± 1.9 pM (k_on 4.04 ± 0.03 × 10⁷ M⁻¹ s⁻¹ and k_off 0.65 ± 0.04 × 10⁻³ s⁻¹). It is slowly consumed by thrombin eventually losing its activity. Contrary, sculptin is hydrolyzed by factor Xa and each polypeptide fragment is able to inhibit thrombin independently. A single domain of sculptin alone retains ~45% of inhibitory activity, which could bind thrombin in a bivalent fashion. The formation of a small turn/helical-like structure by active site binding residues of sculptin might have made it a more potent thrombin inhibitor. In addition, sculptin prolongs global coagulation parameters. In conclusion, sculptin and its independent domain(s) have strong potential to become novel antithrombotic therapeutics.

Serum amyloid A, protein Z, and C4b-binding protein β chain as new potential biomarkers for pulmonary tuberculosis

The aim of this study was to discover novel biomarkers for pulmonary tuberculosis (TB). Differentially expressed proteins in the serum of patients with TB were screened and identified by iTRAQ-two dimensional liquid chromatography tandem mass spectrometry analysis. A total of 79 abnormal proteins were discovered in patients with TB compared with healthy controls. Of these, significant differences were observed in 47 abnormally expressed proteins between patients with TB or pneumonia and chronic obstructive pulmonary disease (COPD). Patients with TB (n = 136) exhibited significantly higher levels of serum amyloid A (SAA), vitamin K-dependent protein Z (PROZ), and C4b-binding protein β chain (C4BPB) than those in healthy controls (n = 66) (P<0.0001 for each) albeit significantly lower levels compared with those in patients with pneumonia (n = 72) (P<0.0001 for each) or COPD (n = 72) (P<0.0001, P<0.0001, P = 0.0016, respectively). After 6 months of treatment, the levels of SAA and PROZ were significantly increased (P = 0.022, P<0.0001, respectively), whereas the level of C4BPB was significantly decreased (P = 0.0038) in treated TB cases (n = 72). Clinical analysis showed that there were significant differences in blood clotting and lipid indices in patients with TB compared with healthy controls, patients with pneumonia or COPD, and treated TB cases (P<0.05). Correlation analysis revealed significant correlations between PROZ and INR (rs = 0.414, P = 0.044), and between C4BPB and FIB (rs = 0.617, P = 0.0002) in patients with TB. Receiver operating characteristic curve analysis revealed that the area under the curve value of the diagnostic model combining SAA, PROZ, and C4BPB to discriminate the TB group from the healthy control, pneumonia, COPD, and cured TB groups was 0.972, 0.928, 0.957, and 0.969, respectively. Together, these results suggested that SAA, PROZ, and C4BPB may serve as new potential biomarkers for TB. Our study may thus provide experimental data for the differential diagnosis of TB.

Novel risk models for early detection and screening of ovarian cancer

PURPOSE

Ovarian cancer (OC) is the most lethal gynaecological cancer. Early detection is required to improve patient survival. Risk estimation models were constructed for Type I (Model I) and Type II (Model II) OC from analysis of Protein Z, Fibronectin, C-reactive protein and CA125 levels in prospectively collected samples from the United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS).

RESULTS

Model I identifies cancers earlier than CA125 alone, with a potential lead time of 3-4 years. Model II detects a number of high grade serous cancers at an earlier stage (Stage I/II) than CA125 alone, with a potential lead time of 2-3 years and assigns high risk to patients that the ROCA Algorithm classified as normal.

MATERIALS AND METHODS

This nested case control study included 418 individual serum samples serially collected from 49 OC cases and 31 controls up to six years pre-diagnosis. Discriminatory logit models were built combining the ELISA results for candidate proteins with CA125 levels.

CONCLUSIONS

These models have encouraging sensitivities for detecting pre-clinical ovarian cancer, demonstrating improved sensitivity compared to CA125 alone. In addition we demonstrate how the models improve on ROCA for some cases and outline their potential future use as clinical tools.

Quantification of protein Z expression in lung adenocarcinoma tissues and cells

As a regulator of coagulation, abnormal Protein Z (PZ) expression may lead to the formation of blood clots in humans. While previous studies have shown that PZ protein is altered in several types of cancer, however, additional observations are needed to understand the complex biology involved. Herein, we investigated local alterations in PZ expression in lung adenocarcinomas by measuring gene and protein expression in both cancerous and normal lung tissues. Twenty-two (22) specimens of lung adenocarcinoma and 22 specimens of normal lung tissues from human patients were compared for the expression of PZ. In addition, A549 adenocarcinoma cells were compared to a normal epithelial cell line, 16-HBE, for in vitro PZ expression. In tissues and cells, PZ protein and gene expression were determined using western blot, immunohistochemistry and PCR. Lung adenocarcinoma tissues showed elevated expression of both PZ mRNA and protein compared with healthy tissue. Only protein expression was increased in cultured cell lines, which holds implications for the dominant source of PZ in tissues, as well as protein modifications necessary for PZ function. Protein Z appears to be associated with the presence of lung adenocarcinoma and may be a viable prognostic biomarker for lung cancer.

Thermodynamic and kinetic characterization of the protein Z-dependent protease inhibitor (ZPI)-protein Z interaction reveals an unexpected role for ZPI Lys-239

The anticoagulant serpin, protein Z-dependent protease inhibitor (ZPI), circulates in blood as a tight complex with its cofactor, protein Z (PZ), enabling it to function as a rapid inhibitor of membrane-associated factor Xa. Here, we show that N,N'-dimethyl-N-(acetyl)-N'-(7-nitrobenz-3-oxa-1,3-diazol-4-yl)ethylenediamine (NBD)-fluorophore-labeled K239C ZPI is a sensitive, moderately perturbing reporter of the ZPI-PZ interaction and utilize the labeled ZPI to characterize in-depth the thermodynamics and kinetics of wild-type and variant ZPI-PZ interactions. NBD-labeled K239C ZPI bound PZ with ∼3 nM KD and ∼400% fluorescence enhancement at physiologic pH and ionic strength. The NBD-ZPI-PZ interaction was markedly sensitive to ionic strength and pH but minimally affected by temperature, consistent with the importance of charged interactions. NBD-ZPI-PZ affinity was reduced ∼5-fold by physiologic calcium levels to resemble NBD-ZPI affinity for γ-carboxyglutamic acid/EGF1-domainless PZ. Competitive binding studies with ZPI variants revealed that in addition to previously identified Asp-293 and Tyr-240 hot spot residues, Met-71, Asp-74, and Asp-238 made significant contributions to PZ binding, whereas Lys-239 antagonized binding. Rapid kinetic studies indicated a multistep binding mechanism with diffusion-limited association and slow complex dissociation. ZPI complexation with factor Xa or cleavage decreased ZPI-PZ affinity 2-7-fold by increasing the rate of PZ dissociation. A catalytic role for PZ was supported by the correlation between a decreased rate of PZ dissociation from the K239A ZPI-PZ complex and an impaired ability of PZ to catalyze the K239A ZPI-factor Xa reaction. Together, these results reveal the energetic basis of the ZPI-PZ interaction and suggest an important role for ZPI Lys-239 in PZ catalytic action.

Rhizoma Pinelliae trypsin inhibitor separation, purification and inhibitory activity on the proliferation of BGC-823 gastric adenocarcinoma cells

The aim of this study was to isolate and purify Rhizoma Pinelliae trypsin inhibitor (RPTI), determine its N-terminal amino acid sequence and evaluate its inhibitory effect on the proliferation of poorly differentiated BGC-823 human gastric adenocarcinoma cells. RPTI was separated and purified from a 40% (NH₄)₂SO₄ precipitate of crude protein extract of Pinellia ternata tuber using affinity chromatography with trypsin as the ligand. The N-terminal amino acid sequence of RPTI was determined using the Edman degradation method. The inhibitory effect of RPTI on BGC-823 cell proliferation was detected in vitro using the MTT method and in vivo in tumour-bearing mice. The purified RPTI showed a single band under SDS-PAGE, its molecular weight was 14 kDa and its N-terminal amino acid sequence was DPVVDG. RPTI inhibited trypsin activity, with an inhibition ratio of 1:6.78 (mass). RPTI significantly inhibited the proliferation of BGC-823 cells in vitro. The IC₅₀ of RPTI was 16.96 μg/ml within 48 h after treatment and 9.61 μg/ml within 72 h after treatment. Subcutaneous injection of RPTI around the tumour significantly inhibited BGC-823 tumour growth in mice. The tumour inhibitory effect was concentration- and dose-dependent. RPTI did not significantly influence the spleen coefficient of the mice. In conclusion, RPTI is a serine proteinase inhibitor with antitumour activity.

Protein Z/protein Z-dependent protease inhibitor system in loco in human gastric cancer

In gastric cancer, hemostatic system components contribute to cancer progression, as activation of factor X (FX) was observed. The protein Z (PZ)/protein Z-dependent protease inhibitor (ZPI) complex inhibits factor Xa proteolytic activity. The purpose of this study was to determine the distribution of ZPI and PZ in relation to FX, and prothrombin fragment (F1 + 2), a standard marker for blood coagulation activation, in human gastric cancer tissue. ABC procedures and a double staining method employed polyclonal antibodies against PZ, FX, and F1 + 2 and a monoclonal antibody against ZPI. In situ hybridization (ISH) methods employed biotin-labeled 25-nucleotide single-stranded DNA probes directed to either PZ or ZPI mRNAs. FX and components of PZ/ZPI coagulation inhibitory system were observed in cancer cells. F1 + 2 was observed in gastric cancer cells as well. Double staining studies revealed FX/PZ, FX/ZPI, and PZ/ZPI co-localization on gastric cancer cells. ISH studies demonstrated the presence of PZ mRNA and ZPI mRNA in gastric cancer cells indicating induced synthesis of these proteins. The co-localization of PZ/ZPI and FX in gastric cancer cells indicates in loco that these proteins may play a role in anticoagulant events at the tumor tissue.