Bovine lactoferrin and Lactoferricin inhibit tumor metastasis in mice

Whey proteins as multifunctional food materials: Recent advancements in hydrolysis, separation, and peptidomimetic approaches

Whey protein derived bioactives, including α-lactalbumin, ß-lactoglobulin, bovine serum albumin, lactoferrin, transferrin, and proteose-peptones, have exhibited wide ranges of functional, biological and therapeutic properties varying from anticancer, antihypertensive, and antimicrobial effects. In addition, their functional properties involve gelling, emulsifying, and foaming abilities. For these reasons, this review article is framed to understand the relationship existed in between those compound levels and structures with their main functional, biological, and therapeutic properties exhibited either in vitro or in vivo. The impacts of hydrolysis mechanism and separation techniques in enhancing those properties are likewise discussed. Furthermore, special emphasize is given to multifunctional effects of whey derived bioactives and their future trends in ameliorating further food, pharmaceutical, and nutraceutical products. The underlying mechanism effects of those properties are still remained unclear in terms of activity levels, efficacy, and targeted effectiveness. For these reasons, some important models linking to functional properties, thermal properties and cell circumstances are established. Moreover, the coexistence of radical trapping groups, chelating groups, sulfhydryl groups, inhibitory groups, and peptide bonds seemed to be the key elements in triggering those functions and properties. Practical Application: Whey proteins are the byproducts of cheese processing and usually the exploitation of these food waste products has increasingly getting acceptance in many countries, especially European countries. Whey proteins share comparable nutritive values to milk products, particularly on their richness on important proteins that can serve immune protection, structural, and energetic roles. The nutritive profile of whey proteins shows diverse type of bioactive molecules like α-lactalbumin, ß-lactoglobulin, lactoferrin, transferrin, immunoglobulin, and proteose peptones with wide biological importance to the living system, such as in maintaining immunological, neuronal, and signaling roles. The diversification of proteins of whey products prompted scientists to exploit the real mechanisms behind of their biological and therapeutic effects, especially in declining the risk of cancer, tumor, and further complications like diabetes type 2 and hypertension risk effects. For these reasons, profiling these types of proteins using different proteomic and peptidomic approaches helps in determining their biological and therapeutic targets along with their release into gastrointestinal tract conditions and their bioavailabilities into portal circulation, tissue, and organs. The wide applicability of those protein fractions and their derivative bioactive products showed significant impacts in the field of emulsion and double emulsion stabilization by playing roles as emulsifying, surfactant, stabilizing, and foaming agents. Their amphoteric properties helped them to act as excellent encapsulating agents, particularly as vehicle for delivering important vitamins and bioactive compounds. The presence of ferric elements increased their transportation to several metal-ions in the same time increased their scavenging effects to metal-transition and peroxidation of lipids. Their richness with almost essential and nonessential amino acids makes them as selective microbial starters, in addition their richness in sulfhydryl amino acids allowed them to act a cross-linker in conjugating further biomolecules. For instance, conjugating gold-nanoparticles and fluorescent materials in targeting diseases like cancer and tumors in vivo is considered the cutting-edges strategies for these versatile molecules due to their active diffusion across-cell membrane and the presence of specific transporters to these therapeutic molecules.

Activity Changes of the Peptic Lactoferrin Hydrolysate in Human Gastric Cancer AGS Cells in Response to Cu(II) or Mn(II) Addition

Lactoferrin is an interesting bioactive protein in milk and can interact with various metal ions of trace elements such as copper, iron, manganese, and others. In this study, a lactoferrin hydrolysate (LFH) was generated from commercial bovine lactoferrin by protease pepsin, fortified with Cu²⁺ (or Mn²⁺) at two levels of 0.64 and 1.28 (or 0.28 and 0.56) mg/g protein, respectively, and then measured for the resultant bioactivity changes in the well-differentiated human gastric cancer AGS cells. The assaying results indicated that the LFH and Cu/Mn-fortified products had long-term anti-proliferation on the cells, while the treated cells showed DNA fragmentation and increased apoptotic cell proportions. Regarding the control cells, the cells treated with the LFH and especially Cu/Mn-fortified LFH had remarkably up-regulated mRNA expression of caspase-3 and Bax by respective 1.21-3.23 and 2.23-2.83 folds, together with down-regulated mRNA expression Bcl-2 by 0.88-0.96 folds. Moreover, Western-blot assaying results also indicated that the cells exposed to the LFH and Cu/Mn-fortified LFH (especially Mn at higher level) for 24 h had an enhanced caspase-3 expression and increased ratio of Bax/Bcl-2. It can thus be concluded that the used Cu/Mn-addition to the LFH may lead to increased bioactivity in the AGS cells; to be more specific, the two metal ions at the used addition levels could endow LFH with a higher ability to cause cell apoptosis by activating caspase-3 and increasing the Bax/Bcl-2 ratio.

Separation Technologies for Whey Protein Fractionation

Whey is a by-product of cheese, casein, and yogurt manufacture. It contains a mixture of proteins that need to be isolated and purified to fully exploit their nutritional and functional characteristics. Protein-enriched fractions and highly purified proteins derived from whey have led to the production of valuable ingredients for many important food and pharmaceutical applications. This article provides a review on the separation principles behind both the commercial and emerging techniques used for whey protein fractionation, as well as the efficacy and limitations of these techniques in isolating and purifying individual whey proteins. The fractionation of whey proteins has mainly been achieved at commercial scale using membrane filtration, resin-based chromatography, and the integration of multiple technologies (e.g., precipitation, membrane filtration, and chromatography). Electromembrane separation and membrane chromatography are two main emerging techniques that have been developed substantially in recent years. Other new techniques such as aqueous two-phase separation and magnetic fishing are also discussed, but only a limited number of studies have reported their application in whey protein fractionation. This review offers useful insights into research directions and technology screening for academic researchers and dairy processors for the production of whey protein fractions with desired nutritional and functional properties.

Identification of LTF as a Prognostic Biomarker for Osteosarcoma

Osteosarcoma remains a major health problem in teenagers. However, its pathogenesis mechanism remains not fully elucidated. This study aims to identify the prognostic biomarkers for osteosarcoma. In this study, we selected genes with a median absolute deviation (MAD) value of the top 5000 in the GSE32981 dataset for subsequent analysis. Weighted correlation network analysis (WGCNA) was used to construct a coexpression network. WGCNA showed that the tan module and midnight blue module were highly correlated with origin and metastases of osteosarcoma, respectively. Enrichment analysis was conducted using genes in the tan module and midnight blue module. A gene coexpression network was constructed by calculating the Spearman correlation coefficients. Four key genes (LTF, C10orf107, HIST1H2AK, and NEXN) were identified to be correlated with the prognosis of osteosarcoma patients. LTF has the highest AUC value, and its effect on osteosarcoma cells was then evaluated. The effect of LTF overexpression on proliferation, migration, and invasion of MG63 and 143B cells was detected by the CCK-8 assay, transwell cell migration assay, and transwell invasion assay, respectively. The overexpression of LTF promoted the proliferation, migration, and invasion of MG63 and 143B cells. In conclusion, LTF may serve as a prognostic biomarker for osteosarcoma.

Lactoferrin from Bovine Milk: A Protective Companion for Life

Lactoferrin (Lf), an iron-binding multifunctional glycoprotein belonging to the transferrin family, is present in most biological secretions and reaches particularly high concentrations in colostrum and breast milk. A key function of lactoferrin is non-immune defence and it is considered to be a mediator linking innate and adaptive immune responses. Lf from bovine milk (bLf), the main Lf used in human medicine because of its easy availability, has been designated by the United States Food and Drug Administration as a food additive that is generally recognized as safe (GRAS). Among the numerous protective activities exercised by this nutraceutical protein, the most important ones demonstrated after its oral administration are: Antianemic, anti-inflammatory, antimicrobial, immunomodulatory, antioxidant and anticancer activities. All these activities underline the significance in host defence of bLf, which represents an ideal nutraceutical product both for its economic production and for its tolerance after ingestion. The purpose of this review is to summarize the most important beneficial activities demonstrated following the oral administration of bLf, trying to identify potential perspectives on its prophylactic and therapeutic applications in the future.

Lactoferrin's Anti-Cancer Properties: Safety, Selectivity, and Wide Range of Action

Despite recent advances in cancer therapy, current treatments, including radiotherapy, chemotherapy, and immunotherapy, although beneficial, present attendant side effects and long-term sequelae, usually more or less affecting quality of life of the patients. Indeed, except for most of the immunotherapeutic agents, the complete lack of selectivity between normal and cancer cells for radio- and chemotherapy can make them potential antagonists of the host anti-cancer self-defense over time. Recently, the use of nutraceuticals as natural compounds corroborating anti-cancer standard therapy is emerging as a promising tool for their relative abundance, bioavailability, safety, low-cost effectiveness, and immuno-compatibility with the host. In this review, we outlined the anti-cancer properties of Lactoferrin (Lf), an iron-binding glycoprotein of the innate immune defense. Lf shows high bioavailability after oral administration, high selectivity toward cancer cells, and a wide range of molecular targets controlling tumor proliferation, survival, migration, invasion, and metastasization. Of note, Lf is able to promote or inhibit cell proliferation and migration depending on whether it acts upon normal or cancerous cells, respectively. Importantly, Lf administration is highly tolerated and does not present significant adverse effects. Moreover, Lf can prevent development or inhibit cancer growth by boosting adaptive immune response. Finally, Lf was recently found to be an ideal carrier for chemotherapeutics, even for the treatment of brain tumors due to its ability to cross the blood-brain barrier, thus globally appearing as a promising tool for cancer prevention and treatment, especially in combination therapies.

Protective effects of whey on rat liver damage induced by chronic alcohol intake

In 2012, alcohol liver disease resulted in 3.3 million-5.9% of global deaths. This study introduced whey protection capacity against chronic alcohol-induced liver injury. Rats were orally administered to 12% ethanol solution in water (ad libitum, average 8.14 g of ethanol/kg body weight (b.w.)/day) alone or combined with whey ( per os, 2 g/kg b.w./day). After 6-week treatment, chronic ethanol consumption induced significant histopathological liver changes: congestion, central vein dilation, hepatic portal vein branch dilation, Kupffer cells hyperplasia, fatty liver changes, and hepatocytes focal necrosis. Ethanol significantly increased liver catalase activity and glutathione reductase protein expression without significant effects on antioxidative enzymes: glutathione peroxidase (GPx), copper-zinc-containing superoxide dismutase (CuZnSOD) and manganese-containing superoxide dismutase (MnSOD). Co-treatment with whey significantly attenuated pathohistological changes induced by ethanol ingestion and increased GSH-Px and nuclear factor kappa B (NF-κB) protein expression. Our results showed positive effects of whey on liver chronically exposed to ethanol, which seem to be associated with NF-κB-GPx signaling.

Antimicrobial peptides with selective antitumor mechanisms: prospect for anticancer applications

In the last several decades, there have been significant advances in anticancer therapy. However, the development of resistance to cancer drugs and the lack of specificity related to actively dividing cells leading to toxic side effects have undermined these achievements. As a result, there is considerable interest in alternative drugs with novel antitumor mechanisms. In addition to the recent approach using immunotherapy, an effective but much cheaper therapeutic option of pharmaceutical drugs would still provide the best choice for cancer patients as the first line treatment. Ribosomally synthesized cationic antimicrobial peptides (AMPs) or host defense peptides (HDP) display broad-spectrum activity against bacteria based on electrostatic interactions with negatively charged lipids on the bacterial surface. Because of increased proportions of phosphatidylserine (negatively charged) on the surface of cancer cells compared to normal cells, cationic amphipathic peptides could be an effective source of anticancer agents that are both selective and refractory to current resistance mechanisms. We reviewed herein the prospect for AMP application to cancer treatment, with a focus on modes of action of cationic AMPs.

A Tetrameric Peptide Derived from Bovine Lactoferricin Exhibits Specific Cytotoxic Effects against Oral Squamous-Cell Carcinoma Cell Lines

Several short linear peptides derived from cyclic bovine lactoferricin were synthesized and tested for their cytotoxic effect against the oral cavity squamous-cell carcinoma (OSCC) cell lines CAL27 and SCC15. As a control, an immortalized and nontumorigenic cell line, Het-1A, was used. Linear peptides based on the RRWQWR core sequence showed a moderate cytotoxic effect and specificity towards tumorigenic cells. A tetrameric peptide, LfcinB(20–25)₄, containing the RRWQWR motif, exhibited greater cytotoxic activity (>90%) in both OSCC cell lines compared to the linear lactoferricin peptide or the lactoferrin protein. Additionally, this tetrameric peptide showed the highest specificity towards tumorigenic cells among the tested peptides. Interestingly, this effect was very fast, with cell shrinkage, severe damage to cell membrane permeability, and lysis within one hour of treatment. Our results are consistent with a necrotic effect rather than an apoptotic one and suggest that this tetrameric peptide could be considered as a new candidate for the therapeutic treatment of OSCC.

Effect of lactoferrin protein on red blood cells and macrophages: mechanism of parasite-host interaction

Background

Lactoferrin is a natural multifunctional protein known to have antitumor, antimicrobial, and anti-inflammatory activity. Apart from its antimicrobial effects, lactoferrin is known to boost the immune response by enhancing antioxidants. Lactoferrin exists in various forms depending on its iron saturation. The present study was done to observe the effect of lactoferrin, isolated from bovine and buffalo colostrum, on red blood cells (RBCs) and macrophages (human monocytic cell line-derived macrophages THP1 cells).

Methods

Lactoferrin obtained from both species and in different iron saturation forms were used in the present study, and treatment of host cells were given with different forms of lactoferrin at different concentrations. These treated host cells were used for various studies, including morphometric analysis, viability by MTT assay, survivin gene expression, production of reactive oxygen species, phagocytic properties, invasion assay, and Toll-like receptor-4, Toll-like receptor-9, and MDR1 expression, to investigate the interaction between lactoferrin and host cells and the possible mechanism of action with regard to parasitic infections.

Results

The mechanism of interaction between host cells and lactoferrin have shown various aspects of gene expression and cellular activity depending on the degree of iron saturation of lactoferrin. A significant increase (P<0.05) in production of reactive oxygen species, phagocytic activity, and Toll-like receptor expression was observed in host cells incubated with iron-saturated lactoferrin when compared with an untreated control group. However, there was no significant (P>0.05) change in percentage viability in the different groups of host cells treated, and no downregulation of survivin gene expression was found at 48 hours post-incubation. Upregulation of the Toll-like receptor and downregulation of the P-gp gene confirmed the immunomodulatory potential of lactoferrin protein.

Conclusion

The present study details the interaction between lactoferrin and parasite host cells, ie, RBCs and macrophages, using various cellular processes and expression studies. The study reveals the possible mechanism of action against various intracellular pathogens such as Toxoplasma, Plasmodium, Leishmania, Trypanosoma, and Mycobacterium. The presence of iron in lactoferrin plays an important role in enhancing the various activities taking place inside these cells. This work provides a lot of information about targeting lactoferrin against many parasitic infections which can rule out the exact pathways for inhibition of diseases caused by intracellular microbes mainly targeting RBCs and macrophages for their survival. Therefore, this initial study can serve as a baseline for further evaluation of the mechanism of action of lactoferrin against parasitic diseases, which is not fully understood to date.

Small lytic peptides escape the inhibitory effect of heparan sulfate on the surface of cancer cells

Background

Several naturally occurring cationic antimicrobial peptides (CAPs), including bovine lactoferricin (LfcinB), display promising anticancer activities. These peptides are unaffected by multidrug resistance mechanisms and have been shown to induce a protective immune response against solid tumors, thus making them interesting candidates for developing novel lead structures for anticancer treatment. Recently, we showed that the anticancer activity by LfcinB was inhibited by the presence of heparan sulfate (HS) on the surface of tumor cells. Based on extensive structure-activity relationship studies performed on LfcinB, shorter and more potent peptides have been constructed. In the present study, we have investigated the anticancer activity of three chemically modified 9-mer peptides and the influence of HS and chondroitin sulfate (CS) on their cytotoxic activity.

Methods

Various cell lines and red blood cells were used to investigate the anticancer activity and selectivity of the peptides. The cytotoxic effect of the peptides against the different cell lines was measured by use of a colorimetric MTT viability assay. The influence of HS and CS on their cytotoxic activity was evaluated by using HS/CS expressing and HS/CS deficient cell lines. The ability of soluble HS and CS to inhibit the cytotoxic activity of the peptides and the peptides' affinity for HS and CS were also investigated.

Results

The 9-mer peptides displayed selective anticancer activity. Cells expressing HS/CS were equally or more susceptible to the peptides than cells not expressing HS/CS. The peptides displayed a higher affinity for HS compared to CS, and exogenously added HS inhibited the cytotoxic effect of the peptides.

Conclusions

In contrast to the previously reported inhibitory effect of HS on LfcinB, the present study shows that the cytotoxic activity of small lytic peptides was increased or not affected by cell surface HS.

Intracellular delivery of bovine lactoferricin's antimicrobial core (RRWQWR) kills T-leukemia cells

Bovine lactoferricin (LfcinB) is a cationic antimicrobial peptide with potent cytotoxic activity against cancer cells. The antimicrobial activity of LfcinB resides in its RRWQWR amino acid sequence (referred to here as LfcinB6); however, the anticancer activity of LfcinB6 is not known. Here, we show that free LfcinB6 did not kill T-leukemia or breast cancer cells but LfcinB6 was strongly cytotoxic when delivered to the cytosolic compartment by fusogenic liposomes. LfcinB6 bound weakly to isolated mitochondria but, unlike LfcinB, did not permeabilize mitochondria or cause cytochrome c to be released. Cathepsin B and caspase activity were important for cytotoxicity caused by intracellular LfcinB6 whereas reactive oxygen species were not involved. The mechanism of LfcinB6-induced cytotoxicity is therefore different from that of LfcinB. We suggest that LfcinB6, in combination with a fusogenic liposome delivery system that selectively targets malignant cells, has potential as a novel anticancer agent.

The anticancer activity of lytic peptides is inhibited by heparan sulfate on the surface of the tumor cells

BACKGROUND

Cationic antimicrobial peptides (CAPs) with antitumor activity constitute a promising group of novel anticancer agents. These peptides induce lysis of cancer cells through interactions with the plasma membrane. It is not known which cancer cell membrane components influence their susceptibility to CAPs. We have previously shown that CAPs interact with the two glycosaminoglycans (GAGs), heparan sulfate (HS) and chondroitin sulfate (CS), which are present on the surface of most cells. The purpose of this study was to investigate the role of the two GAGs in the cytotoxic activity of CAPs.

METHODS

Various cell lines, expressing different levels of cell surface GAGs, were exposed to bovine lactoferricin (LfcinB) and the designer peptide, KW5. The cytotoxic effect of the peptides was investigated by use of the colorimetric MTT viability assay. The cytotoxic effect on wild type CHO cells, expressing normal amounts of GAGs on the cell surface, and the mutant pgsA-745, that has no expression of GAGs on the cell surface, was also investigated.

RESULTS

We show that cells not expressing HS were more susceptible to CAPs than cells expressing HS at the cell surface. Further, exogenously added heparin inhibited the cytotoxic effect of the peptides. Chondroitin sulfate had no effect on the cytotoxic activity of KW5 and only minor effects on LfcinB cytotoxicity.

CONCLUSION

Our results show for the first time that negatively charged molecules at the surface of cancer cells inhibit the cytotoxic activity of CAPs. Our results indicate that HS at the surface of cancer cells sequesters CAPs away from the phospholipid bilayer and thereby impede their ability to induce cytolysis.

Application of thermally responsive elastin-like polypeptide fused to a lactoferrin-derived peptide for treatment of pancreatic cancer

A well characterized, peptide derivative of bovine lactoferrin, L12, has been shown to possess anticancer properties in multiple cell lines. However, adverse side effects in normal tissues and poor plasma kinetics that hinder the clinical effectiveness of current chemotherapeutics also deter the potential for effective delivery of this L12 peptide. To overcome these limitations, we have developed an Elastin-like polypeptide (ELP) carrier that has the potential to thermally target therapeutic peptides and chemotherapeutics to a tumor site. The coding sequence of ELP was modified with the L12 peptide at the C-terminus and a membrane transduction domain derived from the HIV-1 Tat protein at the N-terminus (Tat-ELP-L12). The thermally responsive Tat-ELP1-L12 is soluble in aqueous solutions at 37 degrees C but aggregates near 41 degrees C, which makes Tat-ELP1-L12 ideal for targeting to solid tumors on application of focused hyperthermia. We observed that under hyperthermia conditions at 42 degrees C, Tat-ELP1-L12 mediated cytotoxicity in MIA PaCa-2 pancreatic adenocarcinoma cells was enhanced by nearly thirty-fold. We investigated the mechanisms of cell death and found evidence of mitochondrial membrane depolarization and caspase activation, which are characteristic of apoptosis, as well as, increased membrane permeability, as shown by LDH release. These results suggest that Tat-ELP1-L12 possesses cytotoxic properties to cancer cells in vitro and may have the potential to provide an effective vehicle to thermally target solid tumors.

Bovine lactoferrin supplementation supports immune and antioxidant status in healthy human males

Dietary supplements of bovine lactoferrin are purported in consumer literature to enhance and support the immune system response through their antioxidant, antibacterial, and antiviral properties. Our aim was to investigate more fully the potential immune modulating properties and antioxidant activity of an oral supplementation of bovine lactoferrin in humans. Using an intraindividual repeated measure design, 8 healthy males aged 30 to 55 years, self-administered daily for 21 days, one capsule of placebo for 7 days, followed by 100 mg of lactoferrin for 7 days, followed by 200 mg of lactoferrin for 7 days. Peripheral blood lymphocyte subset counts, T-cell activation, natural killer (NK) cell cytotoxicity, serum cytokine levels (tumor necrosis factor [TNF]-alpha, interferon [IFN]-gamma, interleukin [IL]-2, IL-4, IL-6, and IL-10), and serum hydrophilic, lipophilic, and total antioxidant capacity were repeatedly measured before and after each progressive supplementation. Statistically significant increases were found between presupplementation levels and levels after 200 mg of supplementation in total T-cell activation (as measure by CD3(+)) (P < .001), helper T-cell activation (as measure by CD4(+)) (P < .001), cytotoxic T-cell activation (as measured by CD8(+)) (P < .001), and hydrophilic antioxidant capacity (P < .05). No significant changes were seen in the other parameters measured. These results support the proposal that oral supplements of bovine lactoferrin may be a useful adjunct toward modulation of immune activity, in particular T-cell activation and antioxidant status.

Bovine lactoferrin inhibits Japanese encephalitis virus by binding to heparan sulfate and receptor for low density lipoprotein

Lactoferrin is a natural anti-microbial protein which affects Japanese encephalitis virus (JEV) activity. Binding of lactoferrin to cell surface expressed heparan sulfate (HS), one possible receptor for JEV, has been postulated to be the possible mechanism of anti-JEV antiviral activity. In this study, we evaluate the effects of bovine lactoferrin (bLF) against JEV infection in vitro, using both wild-type (WT) and laboratory-adapted strains. bLF inhibited the infectivity of all the JEV strains tested. In particular the infectivity of the HS-adapted JEV strains was strongly reduced, whereas the non HS-adapted JEV strains were inhibited to lesser extent. Using both HS-adapted CJN-S1 and non HS-adapted CJN-L1 viruses, the results showed that bLF inhibited the early events essential to initiate JEV infection, which includes blocking virus attachment to cellular membranes and reducing viral penetration. This anti-JEV activity was the highest using HS-adapted CJN-S1 strain on HS-expressed CHO-K1 cells. Also, binding of bLF to heparin-sepharose blocked JEV binding; and soluble HS attenuated the anti-JEV activity of bLF. The results support the premise that the interaction of bLF with cell surface expressed glycosaminoglycans, in particular the highly sulfated HS, plays an essential role in the antiviral activity of bLF. However, bLF was functional in inhibiting CJN-S1 entry into HS-deficient CHO-pgsA745 cells, and bLF-treated CHO-K1 and -pgsA745 cells also prevented non HS-adapted CJN-L1 virus entry, indicating that a non-HS pathway may be involved in bLF inhibition of JEV entry. The low-density lipoprotein receptor (LDLR), possibly involved in the entry of several RNA viruses, also binds to bLF. We found that both rLDLR and anti-LDLR antibodies reduced the effectiveness of bLF inhibition of JEV infection. This finding provided evidence to suggest that cell surface-expressed LDLR may play a role in JEV infection, especially for non HS-adapted strains.

Heterologous expression of bovine lactoferricin in Pichia methanolica

According to the bias of codon utilization of Pichia methanolica, a fragment encoding bovine lactoferricin has been cloned and expressed in the P. methanolica under the control of the alcohol oxidase promoter, which was followed by the Saccharomyces cerevisiae alpha-factor signal peptide. The alpha-factor signal peptide efficiently directed the secretion of bovine lactoferricin from the recombinant yeast cell. The recombinant bovine lactoferricin appears to be successfully expressed, as it displays antibacterial activity (antibacterial assay). Moreover, the identity of the recombinant product was estimated by Tricine-SDS-PAGE.

Multifunctional antimicrobial peptides: therapeutic targets in several human diseases

Antimicrobial peptides have emerged as promising agents against antibiotic-resistant pathogens. They represent essential components of the innate immunity and permit humans to resist infection by microbes. These gene-encoded peptides are found mainly in phagocytes and epithelial cells, showing a direct activity against a wide range of microorganisms. Their role has now broadened from that of simply endogenous antibiotics to multifunctional mediators, and their antimicrobial activity is probably not the only primary function. Although antimicrobial peptide deficiency, dysregulation, or overproduction is not known to be a direct cause of any single human disease, numerous studies have now provided compelling evidence for their involvement in the complex network of immune responses and inflammatory diseases, thereby influencing diverse processes including cytokine release, chemotaxis, angiogenesis, wound repair, and adaptive immune induction. The purpose of this review is to highlight recent literature, showing that antimicrobial peptides are associated with several human conditions including infectious and inflammatory diseases, and to discuss current clinical development of peptide-based therapeutics for future use.

Lactoferrin activates macrophages via TLR4-dependent and -independent signaling pathways

Lactoferrin (LF) is a component of innate immunity and is known to interact with accessory molecules involved in the TLR4 pathway, including CD14 and LPS binding protein, suggesting that LF may activate components of the TLR4 pathway. In the present study, we have asked whether bovine LF (bLF)-induced macrophage activation is TLR4-dependent. Both bLF and LPS stimulated IL-6 production and CD40 expression in RAW 264.7 macrophages and in BALB/cJ peritoneal exudate macrophages. However, in macrophages from congenic TLR4(-/-) C.C3-Tlr4(lps-d) mice, CD40 was not expressed while IL-6 secretion was increased relative to wild-type cells. The signaling components NF-kappaB, p38, ERK and JNK were activated in RAW 264.7 cells and BALB/cJ macrophages after bLF or LPS stimulation, demonstrating that the TLR4-dependent bLF activation pathway utilizes signaling components common to LPS activation. In TLR4 deficient macrophages, bLF-induced activation of NF-kappaB, p38, ERK and JNK whereas LPS-induced cell signaling was absent. We conclude from these studies that bLF induces limited and defined macrophage activation and cell signaling events via TLR4-dependent and -independent mechanisms. bLF-induced CD40 expression was TLR4-dependent whereas bLF-induced IL-6 secretion was TLR4-independent, indicating potentially separate pathways for bLF mediated macrophage activation events in innate immunity.

The antimicrobial peptide, lactoferricin B, is cytotoxic to neuroblastoma cellsin vitro and inhibits xenograft growthin vivo

Antimicrobial peptides have been shown to exert cytotoxic activity towards cancer cells through their ability to interact with negatively charged cell membranes. In this study the cytotoxic effect of the antimicrobial peptide, LfcinB was tested in a panel of human neuroblastoma cell lines. LfcinB displayed a selective cytotoxic activity against both MYCN-amplified and non-MYCN-amplified cell lines. Non-transformed fibroblasts were not substantially affected by LfcinB. Treatment of neuroblastoma cells with LfcinB induced rapid destabilization of the cytoplasmic membrane and formation of membrane blebs. Depolarization of the mitochondria membranes and irreversible changes in the mitochondria morphology was also evident. Immuno- and fluorescence-labeled LfcinB revealed that the peptide co-localized with mitochondria. Furthermore, treatment of neuroblastoma cells with LfcinB induced cleavage of caspase-6, -7 and -9 followed by cell death. However, neither addition of the pan-caspase inhibitor, zVAD-fmk, or specific caspase inhibitors could reverse the cytotoxic effect induced by LfcinB. Treatment of established SH-SY-5Y neuroblastoma xenografts with repeated injections of LfcinB resulted in significant tumor growth inhibition. These results revealed a selective destabilizing effect of LfcinB on two important targets in the neuroblastoma cells, the cytoplasmic- and the mitochondria membrane.

Fusion expression of bovine lactoferricin in Escherichia coli

The drug resistance problem has been growing with the utilization of current antibiotics in feed and medical industries. LfcinB, a 25-amino acid antibacterial peptide derived from bovine lactoferrin, is one of potential alternatives of antibiotics. According to the bias of codon utilization of Escherichia coli, a fragment encoding LfcinB has been chemically synthesized, inserted into vector pGEX-4T-2 and expressed in E. coli. The antibacterial peptide was fused with GST with a protease cleavage site located between them. Two constructs with different cleavage sites were made. One construct, pGEX-Th-LfcinB, contains a thrombin cleavage site carried by the vector, and the other, pGEX-Th-Xa-LfcinB, contains a Factor Xa cleavage site which was introduced after the thrombin cleavage site. Fusion protein GST-Th-LfcinB protein was efficiently cleaved by thrombin, yielding recombinant LfcinB showing antibacterial activity. However, fusion protein GEX-Th-Xa-Lfcin B containing Factor Xa recognition site could not be cleaved by Factor Xa at the conditions tried in this study. Successful expression of LfcinB in E. coli provides a possible method to produce LfcinB in large amounts.

Expression of the cationic antimicrobial peptide lactoferricin fused with the anionic peptide in Escherichia coli

Direct expression of lactoferricin, an antimicrobial peptide, is lethal to Escherichia coli. For the efficient production of lactoferricin in E. coli, we developed an expression system in which the gene for the lysine- and arginine-rich cationic lactoferricin was fused to an anionic peptide gene to neutralize the basic property of lactoferricin, and successfully overexpressed the concatemeric fusion gene in E. coli. The lactoferricin gene was linked to a modified magainin intervening sequence gene by a recombinational polymerase chain reaction, thus producing an acidic peptide-lactoferricin fusion gene. The monomeric acidic peptide-lactoferricin fusion gene was multimerized and expressed in E. coli BL21(DE3) upon induction with isopropyl-beta-D-thiogalactopyranoside. The expression levels of the fusion peptide reached the maximum at the tetramer, while further increases in the copy number of the fusion gene substantially reduced the peptide expression level. The fusion peptides were isolated and cleaved to generate the separate lactoferricin and acidic peptide. About 60 mg of pure recombinant lactoferricin was obtained from 1 L of E. coli culture. The purified recombinant lactoferricin was found to have a molecular weight similar to that of chemically synthesized lactoferricin. The recombinant lactoferricin showed antimicrobial activity and disrupted bacterial membrane permeability, as the native lactoferricin peptide does.

Dietary whey protein lowers serum C-peptide concentration and duodenal SREBP-1c mRNA abundance, and reduces occurrence of duodenal tumors and colon aberrant crypt foci in azoxymethane-treated male rats

We evaluated partially hydrolyzed whey protein (WPH) for inhibitory effects on the development of colon aberrant crypt foci (ACF) and intestinal tumors in azoxymethane (AOM)-treated rats. Pregnant Sprague-Dawley rats and their progeny were fed AIN-93G diets containing casein (CAS, control diet) or WPH as the sole protein source. Colons and small intestines from the male progeny were obtained at 6, 12, 20 and 23 weeks after AOM treatment. At 6 and 23 weeks, post-AOM, WPH-fed rats had fewer ACF than did CAS-fed rats. Intestinal tumors were most frequent at 23 weeks, post-AOM. At this time point, differences in colon tumor incidence with diet were not observed; however, WPH-fed rats had fewer tumors in the small intestine (7.6% vs. 26% incidence, P=.004). Partially hydrolized whey protein suppressed circulating C-peptide concentration (a stable indicator of steady-state insulin secretion) at all four time points relative to the corresponding CAS-fed animals. The relative mRNA abundance for the insulin-responsive, transcription factor gene, SREBP-1c, was reduced by WPH in the duodenum but not colon. Results indicate potential physiological linkages of dietary protein type with circulating C-peptide (and by inference insulin), local expression of SREBP-1c gene and propensity for small intestine tumorigenesis.

Antiviral activity of ovotransferrin derived peptides

Ovotransferrin and lactoferrin are iron-binding proteins with antiviral and antibacterial activities related to natural immunity, showing marked sequence and structural homologies. The antiviral activity of two hen ovotransferrin fragments DQKDEYELL (hOtrf(219-227)) and KDLLFK (hOtrf(269-301) and hOtrf(633-638)) towards Marek's disease virus infection of chicken embryo fibroblasts is reported here. These fragments have sequence homology with two bovine lactoferrin fragments with antiviral activity towards herpes simplex virus, suggesting that these fragments could have a role for the exploitation of the antiviral activity of the intact proteins towards herpes viruses. NMR analysis showed that these peptides, chemically synthetized, did not possess any favourite conformation in solution, indicating that both the aminoacid sequence and the conformation they display in the intact protein are essential for the antiviral activity.

Anti-HSV activity of lactoferricin analogues is only partly related to their affinity for heparan sulfate

Earlier studies have shown that the heparan sulfate (HS) on the cell surface acts as a receptor for herpes simplex virus (HSV). We have recently shown that bovine lactoferricin (LfcinB), a small part of the milk protein lactoferrin, inhibits HSV-1 and HSV-2 infection, probably by blocking the entry of the virus. The human homologue (18-42), which shares 36% sequence similarity with LfcinB (17-41), displayed much lower antiviral activity. In the present study, a set of cyclic and linear human and bovine Lfcin derivatives were constructed to investigate the relation between their affinity to HS and chondroitin sulfate (CS) and their antiviral activity against HSV-1 and HSV-2. The lactoferrin (LF) proteins and several of the Lfcin derivatives exhibited similar affinity for HS, but the LF proteins possess a much higher antiviral activity than the smaller peptides. Our structure-activity relationship studies on the Lfcin derivates confirmed that affinity for HS, that was correlated to the net positive charge, is an important factor, but does not well predict the antiviral activity. Structural parameters such as hydrophobicity, molecular size, spatial distribution of charged and lipophilic amino acids, and the cyclic structure of Lfcin also seem to be important factors to govern antiviral activity against HSV.

Search for unknown tumor-antagonizing genes

Following the ingenious prediction of Alfred Knudson in 1971, the first tumor suppressor gene, RB1, has been isolated. Its product, the RB1 protein, was found to play a major role in the control of the cell cycle. The loss of heterozygosity (LOH) technique, introduced by Cavenee and colleagues, was an important milestone toward the confirmation of Knudson's hypothesis and the identification of the gene. Subsequently, the LOH technique has provided important clues that have led to the discovery of other tumor suppressor genes. Most of them play important roles in the regulation of the cell cycle and/or of apoptosis. Circumstantial evidence suggests that still other and perhaps many unknown genes may participate in the protection of the organism against malignant growth. The numerous genome losses in tumors, detected by LOH, comparative genomic hybridization, and by cytogenetic techniques, support this possibility. The early work of one of us (G.K.), together with Henry Harris and Francis Wiener, had shown that the malignant phenotype can be suppressed by hybridizing malignant with low- or non-tumorigenic cells. However, analysis of this phenomenon failed to assign the inhibition of tumorigenicity to any particular gene. We have pursued the search for new tumor-antagonizing genes with two unconventional approaches, focusing on human chromosomal subband 3p21.3, a region frequently targeted by cytogenetically detectable deletions. We have detected four clusters of candidate tumor suppressor genes at 3p21.3 by a combination of deletion mapping and the "elimination test." These findings raise the question whether the number and variety of genes that may contribute to the defense against uncontrolled proliferation may have been underestimated.

Enhanced antitumour activity of 15-residue bovine lactoferricin derivatives containing bulky aromatic amino acids and lipophilic N-terminal modifications

In a structure-antibacterial activity relationship study of a peptide fragment of bovine lactoferricin consisting of FKCRRWQWRMKKLGA (LFB 17-31), it was revealed that the two Trp residues were important for antibacterial activity. It has further been demonstrated that the size, shape and the aromatic character of the side chains were even more important than the Trp itself. In this study the antitumour effect of a series of LFB 17-31 derivatives are reported, in which the two Trp residues in position 6 and 8 were replaced with the larger non-coded aromatic amino acids Tbt, Tpc, Bip and Dip. The counterproductive Cys in position 3 was also substituted with these larger aromatic residues. In addition, the effect of introducing lipophilic groups of different size and shape in the N-terminal of the LFB 17-31 sequence was addressed. The resulting peptide derivatives were tested for activity against three human tumour cell lines and against normal human umbilical vein endothelial cells and fibroblasts. High antitumour activity by several of the peptides demonstrated that Trp successfully could be substituted by the bulky aromatic residues, and peptides containing the large and rigid Tbt residue in position 6 and/or 8 in LFB 17-31 were the most active candidates. The antitumour effect was even more increased by the Tbt-modified peptides when the three counterproductive amino acids Cys3, Gln7 and Gly14 were replaced by Ala. Enhanced antitumour activity was also obtained by modifying the N-terminal of LFB 17-31 with either long-chained fatty acids or bulky moieties. Thus, our results revealed that the size and shape of the lipophilic groups and their position in the peptide sequence were important for antitumour activity.

Physical interaction of Epstein-Barr virus (EBV) nuclear antigen leader protein (EBNA-LP) with human oestrogen-related receptor 1 (hERR1): hERR1 interacts with a conserved domain of EBNA-LP that is critical for EBV-induced B-cell immortalization

Epstein-Barr virus (EBV) nuclear antigen leader protein (EBNA-LP) consists of W1W2 repeats and a unique C-terminal Y1Y2 domain and plays a critical role in EBV-induced transformation. To identify the cellular proteins associating with EBNA-LP, we performed a yeast two-hybrid screen using EBNA-LP cDNA containing a single W1W2 domain as bait and an EBV-transformed human peripheral blood lymphocyte cDNA library as the source of cellular genes. Our results were as follows. (i) A cDNA in the positive yeast colony was found to encode a cellular protein, human oestrogen-related receptor 1 (hERR1), which is a constitutive transcriptional activator of the various types of oestrogen response elements. (ii) A purified chimeric protein consisting of glutathione S-transferase (GST) fused to hERR1 specifically formed complexes with EBNA-LPs containing one (EBNA-LPR1), two (EBNA-LPR2) or four W1W2 repeats (EBNA-LPR4) transiently expressed in COS-7 cells. Reciprocally, GST fused to EBNA-LPR1 or EBNA-LPR2 pulled down hERR1 transiently expressed in COS-7 cells. (iii) Mutational analyses of EBNA-LP revealed that the Y2 domain of EBNA-LP is responsible for the interaction with hERR1 and two leucines in the Y2 domain (Leu-78 and -82), which are conserved among a subset of primate gammaherpesviruses, are interactive sites for hERR1. So far, it has been reported that the only domain of EBNA-LP critical for EBV-induced transformation is the Y1Y2 domain. Potential roles of hERR1 in EBV-induced transformation are discussed.

Anticancer properties of bovine milk

Improved means of cancer prevention and treatment remain key goals of global health programmes. This is particularly true in Western society, where the elderly represent a large proportion of the population, and where the likelihood of tumour development is compounded by risk factors such as poor fibre/high fat diets and environmental pollution. Dietary intervention represents an attractive, non-invasive means of providing anticancer preventative and therapeutic benefits to at-risk individuals. This review focuses on the evidence for anticancer properties of bovine milk and milk-derived components. Evidence of a role for whole milk constituents, as well as purified minor components, in combating tumorigenesis is outlined. Shortcomings in current studies are highlighted, and future opportunities for targeted research to characterize important anticancer properties of milk are discussed.