In vitro anticancer effects of a novel immunostimulant: keyhole limpet hemocyanin

Therapeutic Potential of Marine Peptides in Prostate Cancer: Mechanistic Insights

Prostate cancer (PCa) is the leading cause of cancer death in men, and its treatment is commonly associated with severe adverse effects. Thus, new treatment modalities are required. In this context, natural compounds have been widely explored for their anti-PCa properties. Aquatic organisms contain numerous potential medications. Anticancer peptides are less toxic to normal cells and provide an efficacious treatment approach via multiple mechanisms, including altered cell viability, apoptosis, cell migration/invasion, suppression of angiogenesis and microtubule balance disturbances. This review sheds light on marine peptides as efficacious and safe therapeutic agents for PCa.

Inter-Subunit Dynamics Controls Tunnel Formation During the Oxygenation Process in Hemocyanin Hexamers

Hemocyanin from horseshoe crab in its active form is a homo-hexameric protein. It exists in open and closed conformations when transitioning between deoxygenated and oxygenated states. Here, we present a detailed dynamic atomistic investigation of the oxygenated and deoxygenated states of the hexameric hemocyanin using explicit solvent molecular dynamics simulations. We focus on the variation in solvent cavities and the formation of tunnels in the two conformational states. By employing principal component analysis and CVAE-based deep learning, we are able to differentiate between the dynamics of the deoxy- and oxygenated states of hemocyanin. Finally, our results identify the deoxygenated open conformation, which adopts a stable, closed conformation after the oxygenation process.

Marine peptides in breast cancer: Therapeutic and mechanistic understanding

Breast cancer is the most prevalent invasive form of cancer in females and posing a great challenge for overcoming disease burden. The growth in global cancer deaths mandates the discovery of new efficacious natural anti-tumor treatments. In this regard, aquatic species offer a rich supply of possible drugs. Studies have shown that several marine peptides damage cancer cells by a broad range of pathways, including apoptosis, microtubule balance disturbances, and suppression of angiogenesis. Traditional chemotherapeutic agents are characterized by a plethora of side effects, including immune response suppression. The discovery of novel putative anti-cancer peptides with lesser toxicity is therefore necessary and timely, especially those able to thwart multi drug resistance (MDR). This review addresses marine anti-cancer peptides for the treatment of breast cancer.

Human health and snails

Snails can provide a considerable variety of bioactive compounds for cosmetic and pharmaceutical industries, useful for the development of new formulations with less toxicity and post effects compared to regular compounds used for the purpose. Compounds from crude extract, mucus, slime consist of glycans, polypeptides, proteins, etc., and can be used for curing diseases like viral lesions, warts, and different dermal problems. Some particular uses of snails involve treating post-traumatic stress. Micro RNA of Lymnaea stagnalis, was known to be responsible for the development of long-term memory and treatment of Alzheimer's and Dementia like diseases. This review explores the application of various bioactive compounds from snails with its potential as new translational medicinal and cosmetic applications. Snail bioactive compounds like ω-MVIIA, μ-SIIIA, μO-MrVIB, Xen2174, δ-EVIA, α-Vc1.1, σ-GVIIA, Conantokin-G, and Contulakin-G, conopeptides can be used for the development of anti-cancer drugs. These compounds target the innate immunity and improve the defense system of humans and provide protection against these life-threatening health concerns.AbbreviationsFDA: Food and Drug Administration; UTI: urinal tract infection; nAChRs: nicotinic acetylcholine receptors; NMDA: N-methyl-D-aspartate; CNS: central nervous system; CAR T: chimeric antigen receptors therapy; Micro RNA: micro ribonucleic acid.

Folate-conjugated Helix lucorum hemocyanin - preparation, stability, and cytotoxicity

This is the first report on the modification of a hemocyanin from Helix lucorum (HlH), a large molluscan respiratory protein, with folic acid (FA). In a two-step synthetic reaction, we prepared samples of HlH conjugated with 20 and 50 FA residues denoted as FA-HlH-1 and FA-HlH-2, respectively. Comparison of the attenuated total reflectance-Fourier transform infrared spectra in the amide I band region showed a structural rearrangement in the HlH that is due to FA conjugation. The changes in the secondary structure were more noticeable for FA-HlH-2. The thermal stability of HlH was not significantly affected by the FA modification, which is consistent with the observed structural similarities with the native protein. Preliminary cytotoxicity assays showed that FA-HlH-1 and FA-HlH-2 stimulate fibroblast proliferation when applied in concentrations of 50 and 100 μg/well. A negligible reduction of fibroblast growth was observed only for FA-HlH-1 and FA-HlH-2, exposed to 200 μg/well for 48 h. We found that FA-HlH-2 exhibits a low to moderate cytotoxic effect on two breast cancer cell lines, which express folate receptors, a hormone-dependent (MCF-7) and a hormone-independent (MDA-MB-231). FA-HlH-2 protects nontransformed cells and affects only neoplastic cells, which could be an advantage, and the protein could have potential in combination with other chemotherapeutics.

Immunotherapeutic Potential of Mollusk Hemocyanins in Combination with Human Vaccine Adjuvants in Murine Models of Oral Cancer

Mollusk hemocyanins have been used for decades in immunological and clinical applications as natural, nontoxic, nonpathogenic, and nonspecific immunostimulants for the treatment of superficial bladder cancer, as carriers/adjuvants of tumor-associated antigens in cancer vaccine development and as adjuvants to dendritic cell-based immunotherapy, because these glycoproteins induce a bias towards Th1 immunity. Here, we analyzed the preclinical therapeutic potential of the traditional keyhole limpet hemocyanin (KLH) and two new hemocyanins from Concholepas concholepas (CCH) and Fissurella latimarginata (FLH) in mouse models of oral squamous cell carcinoma. Due to the aggressiveness and deadly malignant potential of this cancer, the hemocyanins were applied in combination with adjuvants, such as alum, AddaVax, and QS-21, which have been shown to be safe and effective in human vaccines, to potentiate their antitumor activity. The immunogenic performance of the hemocyanins in combination with the adjuvants was compared, and the best formulation was evaluated for its antitumor effects in two murine models of oral cancer: MOC7 cells implanted in the flank (heterotopic) and bioluminescent AT-84 E7 Luc cells implanted in the floor of the mouth (orthotopic). The results demonstrated that the hemocyanins in combination with QS-21 showed the greatest immunogenicity, as reflected by a robust, specific humoral response predominantly characterized by IgG2a antibodies and a sustained cellular response manifesting as a delayed hypersensitivity reaction. The KLH- and FLH-QS-21 formulations showed reduced tumor development and greater overall survival. Hemocyanins, as opposed to QS-21, had no cytotoxic effect on either oral cancer cell line cultured in vitro, supporting the idea that the antitumor effects of hemocyanins are associated with their modulation of the immune response. Therefore, hemocyanin utilization would allow a lower QS-21 dosage to achieve therapeutic results. Overall, our study opens a new door to further investigation of the use of hemocyanins plus adjuvants for the development of immunotherapies against oral carcinoma.

Anticancer potential of bioactive peptides from animal sources (Review)

Cancer is the most common cause of human death worldwide. Conventional anticancer therapies, including chemotherapy and radiation, are associated with severe side effects and toxicities as well as low specificity. Peptides are rapidly being developed as potential anticancer agents that specifically target cancer cells and are less toxic to normal tissues, thus making them a better alternative for the prevention and management of cancer. Recent research has focused on anticancer peptides from natural animal sources, such as terrestrial mammals, marine animals, amphibians, and animal venoms. However, the mode of action by which bioactive peptides inhibit the proliferation of cancer cells remains unclear. In this review, we present the animal sources from which bioactive peptides with anticancer activity are derived and discuss multiple proposed mechanisms by which these peptides exert cytotoxic effects against cancer cells.

C-Terminal Domain of Hemocyanin, a Major Antimicrobial Protein from Litopenaeus vannamei: Structural Homology with Immunoglobulins and Molecular Diversity

Invertebrates rely heavily on immune-like molecules with highly diversified variability so as to counteract infections. However, the mechanisms and the relationship between this variability and functionalities are not well understood. Here, we showed that the C-terminal domain of hemocyanin (HMC) from shrimp Litopenaeus vannamei contained an evolutionary conserved domain with highly variable genetic sequence, which is structurally homologous to immunoglobulin (Ig). This domain is responsible for recognizing and binding to bacteria or red blood cells, initiating agglutination and hemolysis. Furthermore, when HMC is separated into three fractions using anti-human IgM, IgG, or IgA, the subpopulation, which reacted with anti-human IgM (HMC-M), showed the most significant antimicrobial activity. The high potency of HMC-M is a consequence of glycosylation, as it contains high abundance of α-d-mannose relative to α-d-glucose and N-acetyl-d-galactosamine. Thus, the removal of these glycans abolished the antimicrobial activity of HMC-M. Our results present a comprehensive investigation of the role of HMC in fighting against infections through genetic variability and epigenetic modification.

Evaluating the potential of the GFAP-KLH immune-tolerizing vaccine for type 1 diabetes in mice

Glial fibrillary acidic protein (GFAP), expressed in peri-islet Schwann cells, is a novel target for the treatment of type 1 diabetes mellitus (T1DM). We designed a GFAP immune-tolerizing vaccine that successfully suppresses hyperglycemia and enhances C peptide secretion. The GFAP vaccine significantly prevented T cell infiltration into pancreatic islets. Moreover, after GFAP vaccination, naïve T-cell differentiation shifted from a cytotoxic Th1- to a Th2-biased humoral response. These results indicate that as a novel target, GFAP reliably predicts the development of T1DM, and that the GFAP vaccine successfully delays the progression of T1DM by regulating T-cell differentiation.

Hemocyanin from Shrimp Litopenaeus vannamei Has Antiproliferative Effect against HeLa Cell In Vitro

Hemocyanin (HMC) has been shown to participate in multiple roles of immune defence. In this study, we investigated the antiproliferative effect and underpinning mechanism of HMC from Litopenaeus vannamei in vitro. Sulforhodamine B (SRB) assay indicated that HMC could dramatically inhibit the growth of HeLa cells, but not 293T cells under the same conditions. Moreover, typical morphological features of apoptosis in HeLa cells including the formation of apoptotic body-like vesicles, chromatin condensation and margination were observed by using 4, 6-diamidino-2- phenylindole dihydrochloride (DAPI) staining and fluorescence analysis. An apoptotic DNA ladder from 180 to 300 bp was also detected. Furthermore, 10 variation proteins associated with apoptosis pathway, viz. G3PDH isoforms 1/2 (G3PDH1/2), aldosereductase, ectodemal dysplasia receptor associated death receptor domain isoform CRA_a (EDARADD), heat shock 60kD protein 1 variant 1 (HSP60), heat shock 70kDa protein 5 precursor (HSP70), heat shock protein 90kDa beta member 1 precursor (HSP90), 14-3-3 protein ζ/δ, Ran and ubiquitin activating enzyme E1(UBE1), were identified from HMC-treated HeLa cells by the proteomic and quantitative real-time RT-PCR strategies. Importantly, the reactive oxygen species (ROS), mitochondrial membrane potential (Δψm) and caspase-9/3 activities were changed significantly in HMC-treated HeLa cells. Together, the data suggests that L. vannamei HMC mediates antiproliferative properties through the apoptosis mechanism involving the mitochondria triggered pathway.

Immunomodulatory properties of shellfish derivatives associated with human health

Some vital components of marine shellfish are documented as an important source for both nutritional and pharmacological applications.

Rapana thomasiana hemocyanin modified with ionic liquids with enhanced anti breast cancer activity

This is the first study on the surface modification of a hemocyanin from marine snail Rapana thomasiana (RtH) with series of imidazolium-based amino acid ionic liquids [emim][AA]. We monitored the induced by [emim][AA] conformational changes in RtH molecule and evaluated the effect of these ionic liquids (ILs) on the protein thermal stability. The cytotoxicity of all obtained RtH-[emim][AA] complexes was assessed toward breast cancer cells (MCF-7) and murine fibroblasts (3T3). As a whole, even small amounts of the tested ILs altered the secondary structure of RtH. The thermal denaturation of RtH in presence of [emim][AA] displayed multi-component transitions, which were shifted toward lower temperatures in comparison to those estimated for the native RtH. The profiles of the RtH-IL calorimetric curves show a clear dependence on the structure of the added salts. In addition, all RtH-[emim][AA] complexes exhibited an enhanced antiprofilerative activity of toward MCF-7 cells in comparison to that of the native RtH. The best results are observed for RtH-[emim][Leu], RtH-[emim][Trp] or RtH-[emim][Ile], which applied in concentration of 700 μg/mL inhibited the MCF-7 cell viability (for 24h) by 66, 63 and 53%, respectively. In addition, these IL-RtH complexes were less cytotoxic to 3T3 cells, i.e. they exhibited some cell specificity.

Keyhole limpet haemocyanin - a model antigen for human immunotoxicological studies

Immunization with a T-cell dependent antigen has been promoted as a reliable and sensitive tool for assessing the influence of putative immunotoxic exposures or agents on immune function. Keyhole limpet haemocyanin (KLH) is a very large, copper-containing protein molecule derived from the haemolymph of the inedible mollusc, Megathura crenulata. KLH is a highly immunogenic T-cell dependent antigen that is used increasingly in immunotoxicological studies, particularly in those involving animals. This report systematically reviews the human clinical studies that have used trans-cutaneous KLH immunization for assessment of the influence of various physiological and disease states and exposures on immune function over the last 20 years (1994-2013). These studies varied in their immunization protocols, formulation of KLH, dose, site and route of administration and immunoassay platforms developed to assess KLH-specific responses. KLH immunization has been well tolerated with only mild to moderate adverse effects reported. Though very promising as a model antigen candidate in immunotoxicology research, more work on standardizing immunization and immunoassay protocols is required.

The addition of recombinant vaccinia HER2/neu to oncolytic vaccinia-GMCSF given into the tumor microenvironment overcomes MDSC-mediated immune escape and systemic anergy

Effective immunotherapeutic strategies require the ability to generate a systemic antigen-specific response capable of impacting both primary and metastatic disease. We have built on our oncolytic vaccinia a granulocyte-macrophage colony-stimulating factor (GM-CSF) strategy by adding recombinant tumor antigen to increase the response in the tumor microenvironment and systemically. In the present study, orthotopic growth of a syngeneic HER2/neu-overexpressing mammary carcinoma in FVB/N mice (NBT1) was associated with increased Gr1(+)CD11b(+) myeloid-derived suppressor cells (MDSCs) both systemically and in the tumor microenvironment. This MDSC population had inhibitory effects on the HER2/neu-specific Th1 immune response. VVneu and VVGMCSF are recombinant oncolytic vaccinia viruses that encode HER2/neu and GM-CSF, respectively. Naive FVB mice vaccinated with combined VVneu and VVGMCSF given systemically developed systemic HER2/neu-specific immunity. NBT1-bearing mice became anergic to systemic immunization with combined VVneu and VVGMCSF. Intratumoral VVGMCSF failed to result in systemic antitumor immunity until combined with intratumoral VVneu. Infection/transfection of the tumor microenvironment with combined VVGMCSF and VVneu resulted in development of systemic tumor-specific immunity, reduction in splenic and tumor MDSC and therapeutic efficacy against tumors. These studies demonstrate the enhanced efficacy of oncolytic vaccinia virus recombinants encoding combined tumor antigen and GM-CSF in modulating the microenvironment of MDSC-rich tumors.

Keyhole limpet hemocyanin augmented the killing activity, cytokine production and proliferation of NK cells, and inhibited the proliferation of Meth A sarcoma cells in vitro

Objective:

Keyhole limpet hemocyanin (KLH) is a popular tumor vaccine carrier protein and an immunostimulant. The present study aimed to investigate the immunoregulatory activity of KLH on cytotoxicity, cytokines production, and proliferation of natural killer (NK) cells. Moreover, antiproliferative activity of KLH on Meth A sarcoma cells was studied.

Materials and Methods:

Cytotoxicity was determined with killing ability of NK cells against yeast artificial chromosome (YAC)-1 cells. Interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) productions by NK cells were measured by enzyme-linked immunosorbent assay (ELISA). Proliferations of NK and Meth A cells were determined by [³H]thymidine incorporated proliferation and 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) methods, respectively.

Results:

KLH at 6.25, 12.5, and 25 μg/well augmented cytotoxicity of NK cells against YAC-1 cells by 2.5, three, and five-times, respectively. KLH at 25 μg/well enhanced IFN-γ and TNF-α productions by 17- and 23-folds, respectively. The proliferation of NK cells was three times stimulated by KLH. The proliferation of Meth A cells was markedly inhibited by all the doses; the highest (4-folds higher) inhibition was observed at a dose of KLH (25 μg/well).

Conclusion:

The study demonstrated the anticancer activity of KLH acting through the induction of NK cells and inhibition of cancer cells. KLH, therefore, may be a good candidate for an anticancer agent alone or in combination with other chemotherapeutic agents.

Anti-cancer properties of gastropodan hemocyanins in murine model of colon carcinoma

BACKGROUND

Various immunotherapeutic approaches have been used for the treatment of cancer. A number of natural compounds are designed to repair, stimulate, or enhance the immune system response. Among them are the hemocyanins (Hcs) - extracellular copper proteins isolated from different arthropod and mollusc species. Hcs are oxygen transporter molecules and normally are freely dissolved in the hemolymph of these animals. Hemocyanins are very promising class of anti-cancer therapeutics due to their immunogenic properties and the absence of toxicity or side effects. KLH (Megathura crenulata hemocyanin) is the most studied molecule of this group setting a standard for natural carrier protein for small molecules and has been used in anti-tumor clinical trials.

RESULTS

The Hcs isolated from marine snail Rapana thomasiana (RtH) and the terrestrial snail Helix pomatia (HpH) express strong in vivo anti-cancer and anti-proliferative effects in the developed by us murine model of colon carcinoma. The immunization with RtH and HpH prolonged the survival of treated animals, improve humoral anti-cancer response and moderate the manifestation of C-26 carcinoma symptoms as tumor growth, splenomegaly and lung metastasis appearance.

CONCLUSION

Hemocyanins are used so far for therapy of superficial bladder cancer and murine melanoma models. Our findings demonstrate a potential anti-cancer effect of hemocyanins on a murine model of colon carcinoma suggesting their use for immunotherapy of different types of cancer.

Formulation of abalone hemocyanin with high antiviral activity and stability

Hemocyanin has been shown to have potential antiviral activity against herpes simplex virus type-1. However, current liquid formulations have short shelf life and high risk of bacterial contamination. The aim of our study was to develop a stable functional formulation. Analytical techniques (nano-differential scanning calorimetry and spectroscopy) and biological assays (cytotoxicity and plaque reduction) were employed to measure the effect of sugar addition on the physical properties and shelf life of the solid formulated hemocyanin. Sucrose improved thermal stability significantly by both increasing the aggregation onset temperature (70°C to>78 °C) and enhancing the activation energy (18%). Lyophilisation without trehalose caused degradation and unfolding of the α-helices of hemocyanin. However, the addition of an optimal proportion of trehalose:protein (5:1 by weight) prevented the degradation and unfolding during lyophilisation, hence maintained the protein solubility. The estimated ED50 values of the formulated solid (0.43±0.1) and liquid samples (0.37±0.06) were similar in magnitude, and were significantly lower than the respective controls; thus, confirming enhanced antiviral activity of the formulation. Formulated compounds were stable for six months at 5 °C storage. The enhanced shelf life and stable antiviral activity of the formulation offers its significant potential as effective therapeutic agent in future clinical applications.

Positions of the glycans in molluscan hemocyanin, determined by fluorescence spectroscopy

Molluscan hemocyanins are glycoproteins with different quaternary and carbohydrate structures. It was suggested that the carbohydrate chains of some Hcs are involved in their antiviral and antitumor effect, as well in the organization of the quaternary structure of the molecules. Using a well-known complex for saccharide sensing, positions and access to the carbohydrate chains in the native hemocyanins from Rapana venosa (RvH) and Helix lucorum (HlH) and also their structural subunits (RvH1, RvH2 and βcHlH) and functional units (FUs) were analysed by fluorescence spectroscopy and circular dichroism. Almost no effect was observed in the fluorescence emission after titration of the complex with native RvH and HlH due to lack of free hydroxyl groups which are buried in the didecameric form of the molecules. Titration with the structural subunits βcHlH and RvH2, increasing of the emission indicates the presence of free hydroxyl groups compared to the native molecules. Complex titration with the structural subunit βc-HlH of H. lucorum Hcs leads to a 2.5 fold increase in fluorescence intensity. However, the highest emission was measured after titration of the complex with FU βcHlH-g. The result was explained by the structural model of βcHlH-g showing the putative position of the glycans on the surface of the molecule. The results of the fluorescent measurements are in good correlation with those of the circular dichroism data, applied to analyse the effect of titration on the secondary structure of the native molecules and functional units. The results also support our previously made suggestion that the N-linked oligosaccharide trees are involved in the quaternary organization of molluscan Hcs.

Evaluation of human antibody responses to keyhole limpet hemocyanin on a carbohydrate microarray

PURPOSE

Keyhole limpet hemocyanin (KLH) is used as a vaccine adjuvant, as a carrier protein for small haptens, and as a treatment for bladder cancer. Immunization with KLH produces antibodies to tumor-associated carbohydrate antigens (TACAs) in animals, and these antibodies have been postulated as the basis of efficacy for bladder cancer treatment. The purpose of this study was to evaluate antibody responses to KLH in humans.

EXPERIMENTAL DESIGN

A carbohydrate microarray was used to profile antibody responses in 14 individuals immunized with KLH plus alum adjuvant.

RESULTS

Eight out of fourteen individuals produced antibodies to at least one TACA. Increases to Lewis X, Lewis Y, GA1di, GM3, and sialyl Lewis A were observed in certain individuals, but, in general, antibody profiles were highly variable. Pre-immunization antibody levels to a subset of array antigens had a statistically significant correlation with the magnitude of the antibody response to KLH.

CONCLUSIONS AND CLINICAL RELEVANCE

Antibodies to TACAs can be produced in humans, but antibody profiles differ considerably from person to person, which may contribute to variable clinical responses with KLH. Pre-treatment antibody levels to certain antigens may be useful for predicting which patients will respond favorably to KLH.

Keyhole limpet hemocyanin induces the activation and maturation of human dendritic cells through the involvement of mannose receptor

Keyhole limpet hemocyanin (KLH) is a xenoantigen largely used in vitro as an immunogen to study primary antigen-specific T cell responses and in vivo as a vaccine component with optimal carrier qualities. So far, the mechanisms by which KLH exerts its immunostimulatory properties are still largely unknown. In particular, although dendritic cells (DCs) play a central role in the initiation and activation of immune responses, the effects of KLH on these cells have been poorly explored. In the present study we investigated the effects of KLH on DCs differentiated in vitro from human monocytes. We observed that KLH promotes the activation and maturation of DCs, as assessed by up-regulation of the surface expression of CD80, CD86, CD40, HLA-DR and CD83. Moreover, even if KLH stimulated the production of IL-12 and IL-10 by DCs, the final balance was clearly in favour of IL-12. According to these stimulatory effects, KLH significantly increased the allostimulatory activity of DCs. To verify whether these effects of KLH may be related to the binding of this highly glycosilated molecule to mannose receptor (MR), we performed inhibition experiments with anti-MR antibody. Results showed that the stimulatory activity of KLH is indeed partially mediated by its interaction with MR. Taken together, our results seem to indicate that KLH does promote the maturation of DCs endowed with the ability to stimulate cell-mediated immune responses. We suggest that this property of KLH may represent a novel further mechanism by which this molecule may exert its efficacy when co-administered with others antigens in immunotherapeutic protocols.

Neuroendocrine regulation of skin dendritic cells

It has long been postulated that stress can affect certain skin conditions, and there is increasing experimental evidence that the neuroendocrine system can directly participate in cutaneous inflammation. Neurohormones, such as glucocorticoids and catecholamines, can reach the skin through the bloodstream after activation of the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system, respectively. Multiple neuropeptides, among them calcitonin gene-related peptide, alpha-melanocyte stimulating hormone, pituitary adenylate cyclase-activating peptide, substance P, vasoactive intestinal peptide, and norepinephrine, may be released by cutaneous nerves or resident and infiltrating cells within the skin. Systemic neuromediators and cutaneous nerves can influence a number of target cells within the skin, among them Langerhans cells. Most of the experimental evidence to date indicates a suppressive effect of the neurohormones and neuropeptides on Langerhans cell function and cutaneous inflammation, but it has become evident lately that the timing of exposure to a stimulus is critical to the outcome of the immune response. Thus, administration of a stress hormone or exposure to a stressor before the dendritic cell (DC) encounters an antigen (Ag) may diminish the immune response toward that Ag, while a stressor may enhance immune function when acting on a maturing DC or before reexposure to the Ag. The neuroendocrine regulation of skin DCs is a complex system allowing for a quick adaptation to various stressors. Such a system, originally evolved to defend the organism against invading pathogens and maintain homeostasis, may under certain conditions become unbalanced and ultimately exacerbate cutaneous inflammation.

Keyhole limpet hemocyanin potentiates standard immunotherapy for melanoma

INTRODUCTION

Our hypothesis was that keyhole limpet hemocyanin (KLH) would augment the effects of standard immunotherapies for melanoma including interferon-alpha (AIFN) and interleukin (IL)-2.

METHODS

The HTB68 melanoma cell line was treated with KLH, AIFN, and IL-2 as single and combined agents. Cell viability, apoptotic activity, and vascular endothelial growth factor levels were all evaluated.

RESULTS

Cell growth was reduced with KLH (28%), AIFN (54%), and IL-2 (29%) (all P < .001). KLH and IL-2 combined exhibited a 47% inhibition of cell growth, whereas KLH and AIFN combined yielded a 67% reduction in cell growth (both P < .001). KLH and AIFN combined significantly increased both early (10%) and late (14%) apoptotic activity compared with controls (5% and 7%, P < .001).

CONCLUSIONS

The additive effects exhibited by the combination of KLH with AIFN or IL-2 are encouraging and support combination therapy as an effective treatment for this aggressive disease.

Inhibition of melanoma growth by hemocyanin occurs via early apoptotic pathways

BACKGROUND

We hypothesized that keyhole limpet hemocyanin (KLH) would reduce cellular proliferation and effect apoptosis of melanoma cell lines in vitro.

METHODS

Two human melanoma cell lines (HTB68 and HTB72) were subjected to a dose-response treatment regimen of KLH (0.4 microg to 100 microg/well). Cell viability was tested by MTT assay (SIGMA, St Louis, MO) at 72 hours. Apoptosis and necrosis were measured by the Annexin V FITC assay (Biovision Inc, Mountain View, CA).

RESULTS

Melanoma cell proliferation was significantly reduced in the HTB68 cell line treated with 6.3 microg or higher doses of KLH. A significant reduction in cell growth was also observed in the HTB72 cells at 50 and 100 microg of KLH. KLH increased early apoptotic activity, whereas both late apoptosis and necrosis were decreased by the addition of KLH.

CONCLUSIONS

KLH significantly reduces cellular proliferation in vitro in melanoma, via early apoptotic pathways. The results warrant in vivo studies into the effects of KLH in melanoma.

In vitro effects of keyhole limpet hemocyanin in breast and pancreatic cancer in regards to cell growth, cytokine production, and apoptosis

BACKGROUND

We have previously shown the inhibitory effects of keyhole limpet hemocyanin (KLH) against breast and pancreatic cancer in vitro. We hypothesize that its actions in breast and pancreas cancer cells are via apoptotic or cytokine pathways.

METHODS

Two breast cancer cell lines, ZR75-1 and MCF-7, and one pancreas cancer cell line, PANC-1, were treated with KLH at 500 mug, 250 mug, and 250 ng/mL. Cell viability, cytokine production, and apoptosis were measured.

RESULTS

Significant growth inhibition was observed in all cell lines at all KLH concentrations tested. Significant changes in cytokine production were observed in all cell lines. An increase in early and late apoptotic activity was observed in the MCF-7, whereas a reduction in late apoptotic activity was observed in the ZR75-1 cells.

CONCLUSIONS

KLH directly inhibits the growth of human breast and pancreas cancer in vitro by apoptotic and nonapoptotic mechanisms.

Antiproliferative and apoptotic effects of rofecoxib on esophageal cancer in vitro1

BACKGROUND

The incidence of Barrett's adenocarcinoma has increased dramatically in the United States, whereas squamous cell carcinoma of the esophagus remains a worldwide problem. Cyclooxygenase (COX)-2 may play an important role in gastrointestinal carcinogenesis and is overexpressed in both Barrett's metaplasia and adenocarcinoma. We hypothesized that a selective and commercially available COX-2 inhibitor, rofecoxib (Vioxx), would inhibit growth of Barrett's adenocarcinoma and squamous cell carcinoma of the esophagus by apoptotic pathways. Additional comparison studies were performed with commercially available COX-2 and COX-1 inhibitors.

MATERIALS AND METHODS

Two esophageal adenocarcinoma cell lines (SEG-1 and BIC) and two esophageal squamous cell cancer lines (KYSE 150 and KYSE 410) were treated with rofecoxib at doses ranging from 8.0 to 125 microg/well. NS-398 (a COX-2 antagonist) and Catechin (a COX-1 antagonist) were also used at doses of 50 and 100 microM. Esophageal cell viability was measured by MTT at 24 and 72 h. Apoptosis was evaluated after 18 h of incubation with rofecoxib, NS398, and Catechin by flow cytometry via annexin V assay.

RESULTS

Rofecoxib, NS-398, and Catechin treatments all resulted in significant antiproliferative effects in both adenocarcinoma and squamous cell carcinoma of the esophagus in vitro. Substantial increases in apoptotic activity were also found in all cell lines.

CONCLUSIONS

Our findings suggest that COX-2 and COX-1 inhibition has potential to become an effective treatment for both histological variants of esophageal cancer. Further in vivo and human studies are warranted to evaluate the safety and clinical utility of these agents in patients with all cancers of the esophagus.

A novel Gal(beta1-4)Gal(beta1-4)Fuc(alpha1-6)-core modification attached to the proximal N-acetylglucosamine of keyhole limpet haemocyanin (KLH) N-glycans

KLH (keyhole limpet haemocyanin), the oxygen-carrying molecule of the marine snail Megathura crenulata, is often used as an adjuvant or as a hapten carrier for immunizations with peptides, oligosaccharides or other low-molecular-mass organic compounds. KLH exhibits several carbohydrate determinants, at least some of which are immunogenic: it shares an antigenic Fuc(alpha1-3)GalNAc-determinant with schistosomes and contains unique Gal-(beta1-6)Man-structural motifs on its N-glycans. This study reveals the presence of N-glycans with unusual +/-Gal(beta1-4)Gal(beta1-4)Fuc- units (alpha1-6)-linked to the reducing end N -acetylglucosamine residue. The following novel structures of KLH N-glycans were deduced by linkage analysis, exoglycosidase digestion, matrix-assisted laser-desorption ionization-tandem MS and nano-LC-ESI-IT-MS (where LC stands for liquid chromatography, ESI for electrospray ionization and IT for ion trap): Man(alpha1-6)[+/-Man(alpha1-3)]Man(beta1-4)GlcNAc(beta1-4)[Gal(beta1-4)Fuc(alpha1-6)]GlcNAc and Man(alpha1-6)Man(beta1-4)GlcNAc(beta1-4)[Gal(beta1-4)Gal(beta1-4)Fuc(alpha1-6)]GlcNAc. The Gal(beta1-4)Fuc- and Gal(beta1-4)Gal(beta1-4)Fuc- core modifications are expected to be immunogenic, similar to other non-mammalian-type core modifications, and to contribute to the immunostimulatory properties of KLH.

Keyhole limpet hemocyanin, a novel immune stimulant with promising anticancer activity in Barrett's esophageal adenocarcinoma

BACKGROUND

Keyhole limpet hemocyanin (KLH) is a recently described immune stimulant and hapten carrier derived from a circulating glycoprotein of the marine mollusk Megathura crenulata. We previously reported that KLH has significant antiproliferative effects in vitro against breast, pancreas, and prostate cancers. We hypothesized that KLH would be effective against Barrett's esophageal adenocarcinoma in an in vitro model.

METHODS

Barrett's esophageal adenocarcinoma cell lines (SEG-1 and BIC-1) were cultured using standard techniques. Cells were plated at 1 x 10(5) and KLH was added at concentrations ranging from 400 ng to 100 microg/well. After 24 and 72 h incubation, cells were assayed for viability using the MTT technique. Statistical analysis was performed using ANOVA. Apoptosis was evaluated using a cell death detection kit after 16 hours of incubation with KLH.

RESULTS

KLH treatment significantly (p < 0.001) reduced viability in a dose and time-dependent manner. Apoptosis was increased in treated SEG-1 cells, but no changes in apoptosis were seen in treated BIC-1 cells.

CONCLUSIONS

KLH directly inhibits the growth of human Barrett's esophageal cancer in vitro by apoptotic and nonapoptotic mechanisms.

The current status of intravesical therapy for superficial bladder cancer

PURPOSE OF REVIEW

To analyse recent advances in intravesical instillation therapy for superficial bladder cancer.

RECENT FINDINGS

Although intravesical bacillus Calmette-Guérin has been used for many years in the treatment of superficial bladder cancer, its mechanism of action remains unclear, its poor tolerance remains a problem, the prediction of its efficacy has still to be validated, and its long-term effects on progression and survival are controversial. The exact timing and place of intravesical chemotherapy needs to be better defined, as well as the place of some new molecules. Finally, new approaches need to be explored for overcoming the limitations of the usual intravesical agents.

SUMMARY

No dramatic advances have been made in understanding the mechanisms of action of bacillus Calmette-Guérin during the past year. However, a careful dissection of this complex immunological pathway continues and immunological criteria are promising for predicting the response to bacillus Calmette-Guérin. Evidence has been accumulating to suggest that a dose reduction during the initial treatment remains effective and reduces side-effects. In addition, bacillus Calmette-Guérin maintenance therapy is useful for high-risk patients. However, long-term tolerance remains an important issue, and the optimal protocol has not yet been defined. On the other hand, it has been proved that intravesical chemotherapy, when administered early after transurethral resection, is effective in preventing frequent recurrences, whereas maintenance chemotherapy is ineffective. Finally, new approaches, including instillations of activated immune cells or targeted gene therapy, are being explored.