Therapeutic efficacy of once-daily oral administration of a Kunitz-type protease inhibitor, bikunin, in a mouse model and in human cancer

An Effective Modification Strategy to Build Multifunctional Peptides Based on a Trypsin Inhibitory Peptide of the Kunitz Family

Peptides with antimicrobial activity or protease inhibitory activity are potential candidates to supplement traditional antibiotics or cancer chemotherapies. However, the potential of many peptides are limited by drawbacks such as cytotoxicity or susceptibility to hydrolysis. Therefore, strategies to modify the structure of promising peptides may represent an effective approach for developing more promising clinical candidates. In this study, the mature peptide OSTI-1949, a Kunitz-type inhibitor from Odorrana schmackeri, and four designed analogues were successfully synthesised. In contrast to the parent peptide, the analogues showed impressive multi-functionality including antimicrobial, anticancer, and trypsin inhibitory activities. In terms of safety, there were no obvious changes observed in the haemolytic activity at the highest tested concentration, and the analogue OSTI-2461 showed an increase in activity against cancer cell lines without cytotoxicity to normal cells (HaCaT). In summary, through structural modification of a natural Kunitz-type peptide, the biological activity of analogues was improved whilst retaining low cytotoxicity. The strategy of helicity enhancement by forming an artificial α-helix and ß-sheet structure provides a promising way to develop original bioactive peptides for clinical therapeutics.

Molecular and pathobiological insights of bikunin/UTI in cancer

Bikunin is a small chondroitin sulfate proteoglycan (PG) with Ser-protease inhibitory activity that plays pleiotropic roles in health and disease. It is involved in several physiological processes including stabilization of the extracellular matrix (ECM) of connective tissues and key reproductive events. Bikunin is also implicated in both acute and chronic inflammatory conditions and represents a non-invasive circulating and/or urinary (as Urinary Trypsin Inhibitor or UTI) biomarker. It exerts inhibitory effects on urokinase-type plasminogen activator (uPA) and its receptor (uPAR) mediating tumor invasiveness by a down-regulation of uPA mRNA expression, thus representing an anti-metastatic agent. However, only limited data on its potential as a diagnostic and/or prognostic marker of cancer have been reported so far. Recent technological advances in mass spectrometry-based proteomics have provided researchers with a huge amount of information allowing for large-scale surveys of the cancer proteome. To address such issues, we analyzed bikunin expression data across several types of tumors, by using UALCAN proteogenomic analysis portal. In this article we critically review the roles of bikunin in human pathobiology, with a special focus on its inhibitory effects and mechanisms in cancer aggressiveness as well as its significance as cancer circulating biomarker.

Conjugation of a Cationic Cell-Penetrating Peptide with a Novel Kunitzin-like Trypsin Inhibitor: New Insights for Enhancement of Peptide Bioactivities

Cationic cell-penetrating peptides (CPPs), such as transactivator of transcription (TAT) peptide, have been proposed as effective drug carriers to improve intracellular delivery of biological macromolecules. Amphibian skin-derived Kunitz-type trypsin inhibitors (KTIs), short counterparts of KTIs from plant sources, were found to possess potent serine protease inhibitory activity. However, poor transmembrane permeability of these molecules has largely hindered the study of the full spectrum of their biological actions. As a result, this study aimed to extend the biological activities of amphibian KTIs by their conjugation to cationic CPPs. Herein, a novel peptide (kunitzin-OV2) and its phenylalanine-substituted analogue F9-kunitzin-OV2 (F9-KOV2) were evaluated for inhibition of trypsin/chymotrypsin and showed weak antibacterial activity against Escherichia coli (E. coli). As expected, the conjugation to TAT peptide did not increase membrane lysis compared with the original kunitzin-OV2, but effectively assisted this complex to enter cells. TAT-kunitzin-OV2 (TAT-KOV2) exhibited a 32-fold increase in antibacterial activity and an enhanced bactericidal rate against E. coli. In addition, the conjugation enabled the parent peptides to exhibit antiproliferative activity against cancer cells. Interestingly, TAT-F9-kunitzin-OV2 (TAT-F9-KOV2) showed stronger antiproliferative activity against human breast cancer (MCF-7) and human glioblastoma (U251MG) cell lines, which TAT-KOV2 did not possess. Moreover, TAT-F9-KOV2 showed a 20–25-fold increase in antiproliferative capacity against human lung cancer (H157, H460) cell lines compared with TAT-KOV2. Therefore, the conjugation of CPPs effectively solves the problem of cell penetration that short KTIs lack and provides evidence for new potential applications for their subsequent development as new antibacterial and anticancer agents.

Is there a role for urokinase-type plasminogen activator inhibitors as maintenance therapy in patients with ovarian cancer?

There is abundant evidence that the urokinase-type plasminogen activator (uPA), its inhibitors PAI-1 and PAI-2 (plasminogen activator inhibitor type-1 and type-2) and its cells surface receptor (uPA-R, CD87) play a fundamental role in tumor invasion and metastasis and are of significant prognostic significance for many tumor types. We performed a systematic Med-line search on uPA, PAI, uPA-R and (epithelial) ovarian cancer (EOC). The majority of malignant EOC specimens show moderate to strong immunostating of tumor and stromal cells. Overexpression of u-PA and PAI-1 can be found in more the 75% of primary ovarian carcinomas, in most metastatic EOC samples and all examined epithelial ovarian cancer cell lines. uPA overexpression in primary specimens was significantly associated with tumor stage, grade, residual disease status after cytoreductive surgery, and poor clinical outcome. This may be explained by increased chemoresistance, a lower resectability and more aggressive tumor biology and tumor dissemination in patients with high uPA and PAI-1. Several therapeutical approaches aimed at inhibiting the uPA/uPAR functions have shown to possess anti-tumor effects in vitro and in animal models. When treating a patient with advanced ovarian cancer it may to be assumed that inhibiting the progression of established (micro) metastases may be more therapeutically relevant than trying to destroy all tumor cells which is not possible in most cases with current systemic treatment modalities. Taking into account the role of uPA and PAI in cell detachment, formation of new stroma, tumor cell reimplantation and metastasis uPA inhibition should be further investigated as maintenance treatment in patients with advanced EOC.

Aberrant methylation of promoter region of SPINT2/HAI-2 gene: an epigenetic mechanism in hepatitis C virus-induced hepatocarcinogenesis

BACKGROUND

Epigenetic changes, including DNA methylation, are recognized as one of the potential mechanisms involved in the pathogenesis of hepatocellular carcinoma (HCC).

AIMS

We aimed to study the methylation status of the promoter region of Serine peptidase inhibitor/hepatocyte growth factor activator inhibitor type 2 (SPINT2/HAI-2) tumor suppressor gene in hepatitis C virus (HCV)-infected cirrhotic patients with and without HCC.

METHODS

Methyl-specific polymerase (MSP) chain reaction was used to detect CpG methylation of the SPINT2/HAI-2 gene promoter in peripheral blood samples of 30 HCC and 50 HCV cirrhotic cases, along with 50 normal individuals.

RESULTS

Aberrant methylation showed a stepwise increase in frequency from 40% in controls to 64% in HCV cirrhotics, and 66.7% in HCC cases with a significant difference among the studied groups (p=0.021). The combined patient groups had an increased risk of aberrant methylation with an odds ratio (OR) of 2.52, a 95% confidence interval (CI) of 1.23-5.14, and a p-value of 0.05 that became more statistically significant after adjusting for age (OR=2.4, 95% CI=1.13-5.26, p-value=0.012), thereby confirming the association between HCV infection and aberrant methylation.

CONCLUSIONS

Our study highlights the role of promoter hypermethylation in the multistep process of hepatocarcinogenesis, providing potential clinical applications in diagnosis and prognosis.

Ulinastatin reduces cancer recurrence after resection of hepatic metastases from colon cancer by inhibiting MMP-9 activation via the antifibrinolytic pathway

High recurrence of colon cancer liver metastasis is observed in patients after hepatic surgery, and the cause is believed to be mostly due to the growth of residual microscopic metastatic lesions within the residual liver. Therefore, triggering the progression of occult metastatic foci may be a novel strategy for improving survival from colon cancer liver metastases. In the present study, we identified an anti-recurrence effect of ulinastatin on colon cancer liver metastasis in mice after hepatectomy. Transwell cell invasion assays demonstrated that ulinastatin significantly inhibited the in vitro invasive ability of colon cancer HCT116 cells. Moreover, gelatin zymography and ELISA analysis showed that MMP-9 activity and plasmin activity of colon cancer HCT116 cells were inhibited by ulinastatin, respectively. Furthermore, in vivo BALB/C nu/nu mice model indicated that ulinastatin effectively reduced recurrence after resection of hepatic metastases from colon cancer. The optimum timing for ulinastatin administration was one week after hepatectomy. Taken together, our findings point to the potential of ulinastatin as an effective approach in controlling recurrence of hepatic metastases from colon cancer after hepatectomy via its anti-plasmin activity.

The P(2)' residue is a key determinant of mesotrypsin specificity: engineering a high-affinity inhibitor with anticancer activity

PRSS3/mesotrypsin is an atypical isoform of trypsin, the up-regulation of which has been implicated in promoting tumour progression. Mesotrypsin inhibitors could potentially provide valuable research tools and novel therapeutics, but small-molecule trypsin inhibitors have low affinity and little selectivity, whereas protein trypsin inhibitors bind poorly and are rapidly degraded by mesotrypsin. In the present study, we use mutagenesis of a mesotrypsin substrate, APPI (amyloid precursor protein Kunitz protease inhibitor domain), and of a poor mesotrypsin inhibitor, BPTI (bovine pancreatic trypsin inhibitor), to dissect mesotrypsin specificity at the key P(2)' position. We find that bulky and charged residues strongly disfavour binding, whereas acidic residues facilitate catalysis. Crystal structures of mesotrypsin complexes with BPTI variants provide structural insights into mesotrypsin specificity and inhibition. Through optimization of the P(1) and P(2)' residues of BPTI, we generate a stable high-affinity mesotrypsin inhibitor with an equilibrium binding constant K(i) of 5.9 nM, a >2000-fold improvement in affinity over native BPTI. Using this engineered inhibitor, we demonstrate the efficacy of pharmacological inhibition of mesotrypsin in assays of breast cancer cell malignant growth and pancreatic cancer cell invasion. Although further improvements in inhibitor selectivity will be important before clinical potential can be realized, the results of the present study support the feasibility of engineering protein protease inhibitors of mesotrypsin and highlight their therapeutic potential.

Urinary trypsin inhibitor as a therapeutic option for endotoxin-related inflammatory disorders

IMPORTANCE OF THE FIELD

Urinary trypsin inhibitor (UTI), a serine protease inhibitor, has been widely used as a drug for patients with inflammatory disorders such as pancreatitis, shock and disseminated intravascular coagulation (DIC). Previous in vitro studies have demonstrated that serine protease inhibitors may have anti-inflammatory properties at sites of inflammation. However, the therapeutic effects of UTI in vivo remain unclarified, as commercial UTI has been developed to act against humans, with the activity and selectivity toward the relevant animal UTI being less characterized.

AREAS COVERED IN THIS REVIEW

In this review, we introduce the roles of UTI in experimental endotoxin (lipopolysaccharide; LPS)-related inflammatory disorders using UTI-deficient (-/-) and corresponding wild-type mice.

WHAT THE READER WILL GAIN

Our experiments using genetic approach suggest that endogenous UTI can protect against the systemic inflammatory response and subsequent organ injury induced by LPS, at least partly, through the inhibition of pro-inflammatory cytokine and chemokine expression, which provide important in vivo evidence and understanding about a protective role of UTI in inflammatory conditions.

TAKE HOME MESSAGE

Using genetically targeted mice selectively lacking UTI, UTI has been evidenced to provide an attractive 'rescue' therapeutic option for endotoxin-related inflammatory disorders such as DIC, acute lung injury and acute liver injury.

Epigenetic inactivation and tumor suppressor activity of HAI-2/SPINT2 in gastric cancer

Hepatocyte growth factor (HGF) activator inhibitor type 2 (HAI-2/SPINT2) encodes Kunitz-type protease inhibitor that regulates HGF activity. Inspection of the human HAI-2/SPINT2 locus uncovered a large and dense CpG island within the 5' region of this gene. Analysis of cultured human gastric tumor lines indicated that HAI-2/SPINT2 expression is either undetectable or in low abundance in several lines; however, enhanced gene expression was measured in cells cultured on the DNA demethylating agent 5-aza-2'-deoxycytidine. Bisulfite DNA sequencing confirmed the densely methylated HAI-2/SPINT2 promoter region. Forced expression of HAI-2/SPINT2 induced cell apoptosis, suppressed anchorage independent growth in vitro and tumor growth in vivo. We investigated HAI-2/SPINT2 aberrant methylation in patients with gastric cancer. The HAI-2/SPINT2 methylation was found preferentially in cancerous tissues (30 of 40, 75%) compared with nontumor tissues (no methylation was detected), indicating that this aberrant characteristic is common in gastric malignancies. In conclusion, epigenetic inactivation of HAI-2/SPINT2 is a common event contributing to gastric carcinogenesis and may be a potential biomarker for gastric cancer.

Mesotrypsin promotes malignant growth of breast cancer cells through shedding of CD109

Serine proteases have been implicated in many stages of cancer development, facilitating tumor cell growth, invasion, and metastasis, and naturally occurring serine protease inhibitors have shown promise as potential anticancer therapeutics. Optimal design of inhibitors as potential therapeutics requires the identification of the specific serine proteases involved in disease progression and the functional targets responsible for the tumor-promoting properties. Here, we use the HMT-3522 breast cancer progression series grown in 3D organotypic culture conditions to find that serine protease inhibitors cause morphological reversion of the malignant T4-2 cells, assessed by inhibition of proliferation and formation of acinar structures with polarization of basal markers, implicating serine protease activity in their malignant growth behavior. We identify PRSS3/mesotrypsin upregulation in T4-2 cells as compared to their nonmalignant progenitors, and show that knockdown of PRSS3 attenuates, and treatment with recombinant purified mesotrypsin enhances, the malignant growth phenotype. Using proteomic methods, we identify CD109 as the functional proteolytic target of mesotrypsin. Our study identifies a new mediator and effector of breast cancer growth and progression.

The ternary structure of the double-headed arrowhead protease inhibitor API-A complexed with two trypsins reveals a novel reactive site conformation

The double-headed arrowhead protease inhibitors API-A and -B from the tubers of Sagittaria sagittifolia (Linn) feature two distinct reactive sites, unlike other members of their family. Although the two inhibitors have been extensively characterized, the identities of the two P1 residues in both API-A and -B remain controversial. The crystal structure of a ternary complex at 2.48 A resolution revealed that the two trypsins bind on opposite sides of API-A and are 34 A apart. The overall fold of API-A belongs to the beta-trefoil fold and resembles that of the soybean Kunitz-type trypsin inhibitors. The two P1 residues were unambiguously assigned as Leu(87) and Lys(145), and their identities were further confirmed by site-directed mutagenesis. Reactive site 1, composed of residues P5 Met(83) to P5' Ala(92), adopts a novel conformation with the Leu(87) completely embedded in the S1 pocket even though it is an unfavorable P1 residue for trypsin. Reactive site 2, consisting of residues P5 Cys(141) to P5' Glu(150), binds trypsin in the classic mode by employing a two-disulfide-bonded loop. Analysis of the two binding interfaces sheds light on atomic details of the inhibitor specificity and also promises potential improvements in enzyme activity by engineering of the reactive sites.

Expression, purification, crystallization and preliminary X-ray diffraction analysis of Sagittaria sagittifolia arrowhead protease inhibitor API-A in complex with bovine trypsin

Protease inhibitors play key roles in physiological processes. Arrowhead protease inhibitor A (API-A), a member of the serine protease inhibitor family, can inhibit two trypsin molecules simultaneously. In the present work, API-A from Sagittaria sagittifolia has been cloned, expressed, purified and crystallized in complex with bovine trypsin. The crystals were obtained by the sitting-drop method. A data set was collected to 2.48 A resolution from a single crystal. The crystal belonged to space group C222(1), with unit-cell parameters a = 76.63, b = 110.86, c = 152.99 A, alpha = beta = gamma = 90 degrees .

Drug development against metastasis-related genes and their pathways: a rationale for cancer therapy

It is well recognized that the majority of cancer related deaths is caused by metastatic diseases. Therefore, there is an urgent need for the development of therapeutic intervention specifically targeted to the metastatic process. In the last decade, significant progress has been made in this research field, and many new concepts have emerged that shed light on the molecular mechanism of metastasis cascade which is often portrayed as a succession of six distinct steps; localized invasion, intravasation, translocation, extravasation, micrometastasis and colonization. Successful metastasis is dependent on the balance and complex interplay of both the metastasis promoters and suppressors in each step. Therefore, the basic strategy of our interventions is aimed at either blocking the promoters or potentiating the suppressors in this disease process. Toward this goal, various kinds of antibodies and small molecules have been designed. These include agents that block the ligand-recepter interaction of metastasis promoters (HGF/c-Met), antagonize the metastasis-promoting enzymes (AMF, uPA and MMP) and inhibit the transcriptional activity of metastasis promoter (beta-Catenin). On the other hand, the intriguing roles of metastasis suppressors and their signal pathways have been extensively studied and various attempts have been made to potentiate these factors. Small molecules have been developed to restore the expression or mimic the function of metastasis-suppressor genes such as NM23, E-cadherin, Kiss-1, MKK4 and NDRG1, and some of them are under clinical trials. This review summarizes our current understanding of the molecular pathway of tumor metastasis and discusses strategies and recent development of anti-metastatic drugs.

Structural analysis of bikunin glycosaminoglycan

The structure of an intact glycosaminoglycan (GAG) chain of the bikunin proteoglycan (PG) was analyzed using a combined top-down and bottom-up sequencing strategy. PGs are proteins with one or more linear, high-molecular weight, sulfated GAG polysaccharides O-linked to serine or threonine residues. GAGs are often responsible for the biological functions of PGs, and subtle variations in the GAG structure have pronounced physiological effects. Bikunin is a serine protease inhibitor found in human amniotic fluid, plasma, and urine. Bikunin is posttranslationally modified with a chondroitin sulfate (CS) chain, O-linked to a serine residue of the core protein. Recent studies have shown that the CS chain of bikunin plays an important role in the physiological and pathological functions of this PG. While no PG or GAG has yet been sequenced, bikunin, the least complex PG, offers a compelling target. Electrospray ionization Fourier transform-ion cyclotron resonance mass spectrometry (ESI FTICR-MS) permitted the identification of several major components in the GAG mixture having molecular masses in a range of 5505-7102 Da. This is the first report of a mass spectrum of an intact GAG component of a PG. FTICR-MS analysis of a size-uniform fraction of bikunin GAG mixture obtained by preparative polyacrylamide gel electrophoresis, allowed the determination of chain length and number of sulfo groups in the intact GAGs.

Roles of Kunitz domains in the anti-invasive effect of hepatocyte growth factor activator inhibitor type 1 in human glioblastoma cells

Hepatocyte growth factor activator inhibitor type 1 (HAI-1) is a membrane-bound serine proteinase inhibitor having two extracellular Kunitz-type proteinase inhibitor domains (KD) namely KD-1 and KD-2. It efficiently inhibits hepatocyte growth factor activator, matriptase, hepsin, prostasin and trypsin. We have previously reported that the expression of HAI-1 suppresses the in vitro invasive capability of human glioblastoma cells. In this study we examined the role of each KD in the anti-invasive effect of HAI-1. Engineered over-expression of the mature membrane-form HAI-1 suppressed in vitro fibrin gel invasion of two human glioblastoma cell lines, U251 and YKG-1. The migratory activity on type IV collagen was also suppressed by the HAI-1 expression. These effects were not affected by the deletion of intracytoplasmic domain of HAI-1. A truncated secreted form of HAI-1 also suppressed in vitro invasion of the cells, indicating that the extracellular portion of HAI-1 was responsible for the anti-invasive effect. To determine the roles of each KD in the anti-invasive effect of HAI-1 in vitro, we constructed expression plasmids for HAI-1 with or without mutation at the P1 position of the reactive site of each KD. The results revealed that the proteinase inhibitor activity of N-terminal KD (KD-1) is responsible for the anti-invasion effect of HAI-1.

Enhanced spontaneous metastasis in bikunin-deficient mice

Previously, we showed that bikunin, a Kunitz-type protease inhibitor, inhibits invasion and metastasis in several types of cancer cells possibly through suppression of upregulation of urokinase-type plasminogen activator (uPA) expression. Bikunin corresponds to a light chain of the inter-alpha inhibitor. To explore critical role of endogenous bikunin, we used bikunin knockout (Bik-/-) mice. Here, we show that 1) higher frequency of spontaneous 3LL lung metastasis was observed in Bik-/- mice compared to Bik+/+ mice, suggesting that bikunin deficiency increases the sensitivity of mice to lung metastasis; 2) administration of exogenous bikunin caused a significant reduction of lung metastasis in Bik-/- and Bik+/+ mice; 3) primary and metastatic tumors significantly upregulated uPA and PAI-1 expression in Bik-/- mice relative to Bik+/+ mice at least through phosphorylation of ERK1/2 and 4) exogenous bikunin suppressed phosphorylation of ERK1/2 and upregulation of uPA and PAI-1 expression in 3LL cells in response to G-CSF. These data allow us to conclude that the increased sensitivity of Bik-/- mice to lung metastasis in vivo is due to a lack of circulating proteins of the inter-alpha inhibitor family, especially bikunin.

Immunosuppressive activity of proteases in cervical carcinoma

OBJECTIVE

The host immune response is essential for restraining both HPV infections and HPV-related cervical cancer. We previously reported a direct correlation between proteolytic activity and malignant progression from precursor lesions to invasive cervical carcinoma. The present study was undertaken to investigate whether proteinases from cervical carcinoma extracts and representative purified proteinases involved in tumor progression could regulate lymphocyte proliferation to phytohemagglutinin (PHA) mitogen.

METHODS

Extracts were prepared from tissue samples obtained from patients with invasive cervical squamous carcinoma, squamous intra-epithelial lesions or women with normal cervix. Lymphocytes obtained from a single healthy donor were pre-incubated with one of these extracts in the presence or absence of proteinase inhibitors, and stimulated with PHA during 72 h. The proliferative response was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) method (re-validated with thymidine uptake).

RESULTS

Lymphocyte proliferation was significantly decreased by cervical carcinoma extracts, while only slightly decreased by squamous intra-epithelial lesions or normal extracts. Inhibitor assays indicated that proteinases from cervical carcinoma were responsible for 53.30% of total suppressive activity. We found that purified enzymes such as trypsin, cathepsin B, uPA and type IV collagenase suppressed the proliferative response in a dose-dependent fashion.

CONCLUSIONS

Our data suggest that in addition to the classic role in tumor invasion, proteases could represent an immune evasion mechanism in cervical carcinoma.

Tumor Suppressor Activity and Epigenetic Inactivation of Hepatocyte Growth Factor Activator Inhibitor Type 2/SPINT2 in Papillary and Clear Cell Renal Cell Carcinoma

Following treatment with a demethylating agent, 5 of 11 renal cell carcinoma (RCC) cell lines showed increased expression of hepatocyte growth factor (HGF) activator inhibitor type 2 (HAI-2/SPINT2/Bikunin), a Kunitz-type protease inhibitor that regulates HGF activity. As activating mutations in the MET proto-oncogene (the HGF receptor) cause familial RCC, we investigated whether HAI-2/SPINT2 might act as a RCC tumor suppressor gene. We found that transcriptional silencing of HAI-2 in RCC cell lines was associated with promoter region methylation and HAI-2/SPINT2 protein expression was down-regulated in 30% of sporadic RCC. Furthermore, methylation-specific PCR analysis revealed promoter region methylation in 30% (19 of 64) of clear cell RCC and 40% (15 of 38) of papillary RCC, whereas mutation analysis (in 39 RCC cell lines and primary tumors) revealed a missense substitution (P111S) in one RCC cell line. Restoration of HAI-2/SPINT2 expression in a RCC cell line reduced in vitro colony formation, but the P111S mutant had no significant effect. Increased cell motility associated with HAI-2/SPINT2 inactivation was abrogated by treatment with extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) and phospholipase C-gamma inhibitors, but not by an inhibitor of atypical protein kinase C. These findings are consistent with frequent epigenetic inactivation of HAI-2/SPINT2, causing loss of RCC tumor suppressor activity and implicate abnormalities of the MET pathway in clear cell and papillary sporadic RCC. This information provides opportunities to develop novel targeted approaches to the treatment of RCC.

Bikunin inhibits lipopolysaccharide-induced tumor necrosis factor alpha induction in macrophages

Bikunin, a Kunitz-type protease inhibitor, exhibits anti-inflammatory activity in protection against cancer and inflammation. To investigate the molecular mechanism of this inhibition, we analyzed the effect of bikunin on tumor necrosis factor alpha (TNF-alpha) production in human peripheral mononuclear cells stimulated by lipopolysaccharide (LPS), an inflammatory inducer. Here, we show the following results. (i) LPS induced TNF-alpha expression in time- and dose-dependent manners through phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase pathways. (ii) Bikunin inhibits LPS-induced up-regulation of TNF-alpha protein expression in a dose-dependent manner, reaching 60% inhibition at the highest doses of bikunin tested (5.0 microM). (iii) Inhibition by bikunin of TNF-alpha induction correlates with the suppressive capacity of ERK1/2, JNK, and p38 signaling pathways, implicating repressions of at least three different signals in the inhibition. (iv) Bikunin blocks the induction of TNF-alpha target molecules interleukin-1beta (IL-1beta) and IL-6 proteins. (v) Bikunin is functional in vivo, and this glycoprotein blocks systemic TNF-alpha release in mice challenged with LPS. (vi) Finally, bikunin can prevent LPS-induced lethality. In conclusion, bikunin significantly inhibits LPS-induced TNF-alpha production, suggesting a mechanism of anti-inflammation by bikunin through control of cytokine induction during inflammation. Bikunin might be a candidate for the treatment of inflammation, including septic shock.

Dietary supplementation of soybean kunitz trypsin inhibitor reduces lipopolysaccharide-induced lethality in mouse model

We examined the modifying effects of a Kunitz trypsin inhibitor (KTI) and a Bowman-Birk trypsin inhibitor (BBI), purified from soybean, as intraperitoneal (i.p.) injection and dietary supplements on bacterial lipopolysaccharide (LPS)-induced lethality in mice. We initially examined the suppressing effects of i.p. injection of KTI (50 mg/kg) and BBI (50 mg/kg) on LPS-induced lethality after i.p. injection of LPS. Furthermore, groups of female C57BL/6 were fed a basal diet (control group) or the basal diet supplemented with KTI (50 g/kg) or BBI (50 g/kg). Here, we show that i.p. and daily oral administration of KTI, but not BBI, caused a significant reduction of the LPS-induced lethality; that LPS significantly induced plasma TNF-alpha, IL-1beta, and IL-6 levels in mice after LPS challenge; that concomitant administration of KTI, but not BBI, inhibits the LPS-induced plasma levels of these cytokines; and that KTI, but not BBI, suppressed LPS-induced upregulation of cytokine expression through suppression of phosphorylation of three mitogen-activated protein (MAP) kinase pathways, ERK1/2, JNK, and p38, in peritoneal macrophages. These data allow us to speculate that i.p. injection and dietary supplementation of a soybean KTI may play a role as a potent anti-inflammatory agent by inhibiting activation of MAP kinases, leading to the suppression of cytokine expression.

Plasma bikunin as a favorable prognostic factor in ovarian cancer

PURPOSE

Bikunin is a multifunctional glycoprotein, which mediates suppression of tumor cell invasion and metastasis. The measurement of bikunin levels in the tissue of patients with malignant diseases has been introduced as a new and simple diagnostic tool for the evaluation of prognosis. The high bikunin expression in ovarian cancer tissue would enable the use of soluble bikunin protein present in the circulation of ovarian cancer patients as a biomarker of disease.

PATIENTS AND METHODS

We developed a double-antibody immunoassay for bikunin and detected its presence in normal human circulation. We quantified, by enzyme-linked immunosorbent assay and/or immunoblot assay bikunin in sera from 200 healthy women (controls), 200 patients with benign gynecologic diseases, and 327 patients with ovarian cancer before surgical removal of the tumor.

RESULTS

When the values of bikunin corresponding to the median were used as the cutoff value (11.5 microg/mL), low plasma bikunin was strongly associated with late-stage, suboptimal debulking with large residual tumor (> 2 cm) and low response to chemotherapy. The median survival time of the patients with a high bikunin level was more than 60 months as compared with 26 months among those with low bikunin level (P = .002). This difference corresponded to a 2.2-fold increased risk of dying for the lower plasma bikunin patients (hazard ratio, 0.45; P = .023) and remained significant in multivariate analysis (hazard ratio, 0.63; P = .041).

CONCLUSION

Preoperative plasma bikunin concentration is a strong and independent favorable prognostic marker for ovarian cancer.

Expression and characterization of the first kunitz domain of human tissue factor pathway inhibitor-2

Human tissue factor pathway inhibitor-2 (hTFPI-2) has three kunitz domains whose structure and function are unclear. We expressed the first kunitz domain of hTFPI-2 (hTFPI-2/KD1) as functional form using Pichia pastoris and investigated its characterization. In the experiment, hTFPI-2/KD1 can inhibit the plasmin and trypsin activity and the Ki of hTFPI-2/KD1 towards plasmin (30nM) and trypsin (50nM) was determined as 10 and 7nM by chromogenic assay, respectively. hTFPI-2/KD1 can also inhibit MMP-2 and MMP-9 in zymography assay. Furthermore, the inhibition of hTFPI-2/KD1 to the Matrigel invasion by HT-1080 is also described. This study provides a method to produce hTFPI-2/KD1 efficiently and some insights into the structure and function of hTFPI-2/KD1.

Structure-Function Analysis of the Reactive Site in the First Kunitz-type Domain of Human Tissue Factor Pathway Inhibitor-2

Human tissue factor pathway inhibitor-2 (TFPI-2) is a Kunitz-type proteinase inhibitor that regulates a variety of serine proteinases involved in coagulation and fibrinolysis through their non-productive interaction with a P(1) residue (Arg-24) in its first Kunitz-type domain (KD1). Previous kinetic studies revealed that TFPI-2 was a more effective inhibitor of plasmin than several other serine proteinases, but the molecular basis for this specificity was unclear. In this study, we employed molecular modeling and mutagenesis strategies to produce several variants of human TFPI-2 KD1 in an effort to identify interactive site residues other than the P(1) Arg that contribute significantly to its inhibitory activity and specificity. Molecular modeling of KD1 based on the crystal structure of bovine pancreatic trypsin inhibitor revealed that KD1 formed a more energetically favorable complex with plasmin versus trypsin and/or the factor VIIa-tissue factor complex primarily due to strong ionic interactions between Asp-19 (P(6)) and Arg residues in plasmin (Arg-644, Arg-719, and Arg-767), Arg-24 (P(1)) with Asp-735 in plasmin, and Arg-29 (P(5)') with Glu-606 in plasmin. In addition, Leu-26 through Leu-28 (P(2)'-P(4)') in KD1 formed strong van der Waals contact with a hydrophobic cluster in plasmin (Phe-583, Met-585, and Phe-587). Mutagenesis of Asp-19, Tyr-20, Arg-24, Arg-29, and Leu-26 in KD1 resulted in substantial reductions in plasmin inhibitory activity relative to wild-type KD1, but the Asp-19 and Tyr-20 mutations revealed the importance of these residues in the specific inhibition of plasmin. In addition to the reactive site residues in the P(6)-P(5)' region of KD1, mutation of a highly conserved Phe at the P(18)' position revealed the importance of this residue in the inhibition of serine proteinases by KD1. Thus, together with the P(1) residue, the nature of other residues flanking the P(1) residue, particularly at P(6) and P(5)', strongly influences the inhibitory activity and specificity of human TFPI-2.

Suppressing effects of dietary supplementation of soybean trypsin inhibitor on spontaneous, experimental and peritoneal disseminated metastasis in mouse model

The modifying effects of a Kunitz trypsin inhibitor (KTI) and a Bowman-Birk trypsin inhibitor (BBI), purified from soybean trypsin inhibitor, as dietary supplements on experimental and spontaneous pulmonary metastasis of murine Lewis lung carcinoma 3LL cells as well as peritoneal disseminated metastasis model in human ovarian cancer HRA cells were investigated in i.v., s.c. and i.p. injection models in mice. Seven groups of female C57BL/6 or nude mice were fed a basal diet (control group) or the basal diet supplemented with KTI or BBI (5, 15, or 50 g/kg). Here we show that, in an in vivo spontaneous metastasis assay, the diet supplementation with KTI (15 and 50 g/kg), but not with BBI, for 28 days immediately after s.c. tumor cell inoculation significantly inhibited the formation of lung metastasis in C57BL/6 mice in a dose-dependent manner. The inhibition of lung metastasis was not due to direct antitumor effects of KTI. In an in vivo experimental metastasis assay, the diet supplementation with KTI or BBI for 21 days after i.v. tumor cell inoculation did not reduce the number of lung tumor colonies. In addition, KTI (15 or 50 g/kg) treatment in a peritoneal disseminated metastasis model of HRA cells resulted in a 40% reduction in total tumor burden when compared with control animals. Immunoblot analysis revealed that KTI specifically reduced expression of uPA protein as well as phosphorylation of MAP kinase and PI3 kinase proteins in the cells stimulated with agonists (G-CSF for 3LL cells or TGF-beta1 for HRA cells). These results suggest that dietary supplementation of KTI more efficiently regulates the mechanism involved in the entry into vascular circulation of tumor cells (intravasation) than in extravasation during the metastatic process. KTI treatment may also be beneficial for ovarian cancer patients with or at risk for peritoneal disseminated metastasis; it greatly reduces tumor burden in part by inhibiting phosphorylation of MAP kinase and PI3 kinase, leading to suppression of uPA expression.