Mistletoe lectin induces apoptosis and telomerase inhibition in human A253 cancer cells through dephosphorylation of Akt

Lectins in oncology and virology: Mechanisms of anticancer activity and SARS-CoV-2 inhibition

Lectins are proteins or glycoproteins of non-immune origin with carbohydrate-binding properties. They are found both prokaryotic and eukaryotic organisms. The most abundant source of the lectins are plants. Many lectins have anticancer effects by directly exerting cytotoxic effects on malignant cells or indirectly activating the immune system. Lectins also have antiviral activities. These proteins can recognise glycoproteins on the surface of enveloped viruses and bind to them. This creates a physical barrier between them and the corresponding receptors on the surface of the host cell, which prevents the virus from entering the cell and can thus effectively inhibit the replication of the virus. In this review, we focus on the anticancer activities of selected lectins and the underlying mechanisms. We also discuss different types of lectins with antiviral activity. We have paid special attention to lectins with inhibitory activity against SARS-CoV-2. Finally, we outline the challenges of using lectins in therapy and suggest future research directions.

Patients with Advanced or Metastasised Non-Small-Cell Lung Cancer with Viscum album L. Therapy in Addition to PD-1/PD-L1 Blockade: A Real-World Data Study

Immunotherapy with PD-1/PD-L1 inhibitors has significantly improved the survival rates of patients with metastatic non-small-cell lung cancer (NSCLC). Results of a real-world data study investigating add-on VA (Viscum album L.) to chemotherapy have shown an association with the improved overall survival of patients with NSCLC. We sought to investigate whether the addition of VA to PD-1/PD-L1 inhibitors in patients with advanced or metastasised NSCLC would have an additional survival benefit. In the present real-world data study, we enrolled patients from the accredited national registry, Network Oncology, with advanced or metastasised NSCLC. The reporting of data was performed in accordance with the ESMO-GROW criteria for the optimal reporting of oncological real-world evidence (RWE) studies. Overall survival was compared between patients receiving PD-1/PD-L1 inhibitor therapy (control, CTRL group) versus the combination of anti-PD-1/PD-L1 therapy and VA (combination, COMB group). An adjusted multivariate Cox proportional hazard analysis was performed to investigate variables associated with survival. From 31 July 2015 to 9 May 2023, 415 patients with a median age of 68 years and a male/female ratio of 1.2 were treated with anti-PD-1/PD-L1 therapy with or without add-on VA. Survival analyses included 222 (53.5%) patients within the CRTL group and 193 (46.5%) in the COMB group. Patients in the COMB group revealed a median survival of 13.8 months and patients in the CRTL group a median survival of 6.8 months (adjusted hazard ratio, aHR: 0.60, 95% CI: 0.43-0.85, p = 0.004) after adjustment for age, gender, tumour stage, BMI, ECOG status, oncological treatment, and PD-L1 tumour proportion score. A reduction in the adjusted hazard of death by 56% was seen with the addition of VA (aHR 0.44, 95% CI: 0.26-0.74, p = 0.002) in patients with PD-L1-positive tumours (tumour proportion score > 1%) treated with first-line anti-PD-1/PD-L1 therapy. Our findings suggest that add-on VA correlates with improved survival in patients with advanced or metastasised NSCLC who were treated with PD-1/PD-L1 inhibitors irrespective of age, gender, tumour stage, or oncological treatment. The underlying mechanisms may include the synergistic modulation of the immune response. A limitation of this study is the observational non-randomised study design, which only allows limited conclusions to be drawn and prospective randomised trials are warranted.

Elucidating the glycan-binding specificity and structure of Cucumis melo agglutinin, a new R-type lectin

Plant lectins have garnered attention for their roles as laboratory probes and potential therapeutics. Here, we report the discovery and characterization of Cucumis melo agglutinin (CMA1), a new R-type lectin from melon. Our findings reveal CMA1's unique glycan-binding profile, mechanistically explained by its 3D structure, augmenting our understanding of R-type lectins. We expressed CMA1 recombinantly and assessed its binding specificity using multiple glycan arrays, covering 1,046 unique sequences. This resulted in a complex binding profile, strongly preferring C2-substituted, beta-linked galactose (both GalNAc and Fuca1-2Gal), which we contrasted with the established R-type lectin Ricinus communis agglutinin 1 (RCA1). We also report binding of specific glycosaminoglycan subtypes and a general enhancement of binding by sulfation. Further validation using agglutination, thermal shift assays, and surface plasmon resonance confirmed and quantified this binding specificity in solution. Finally, we solved the high-resolution structure of the CMA1 N-terminal domain using X-ray crystallography, supporting our functional findings at the molecular level. Our study provides a comprehensive understanding of CMA1, laying the groundwork for further exploration of its biological and therapeutic potential.

Recent advances in the use of legume lectins for the diagnosis and treatment of breast cancer

Poor lifestyle choices and genetic predisposition are factors that increase the number of cancer cases, one example being breast cancer, the third most diagnosed type of malignancy. Currently, there is a demand for the development of new strategies to ensure early detection and treatment options that could contribute to the complete remission of breast tumors, which could lead to increased overall survival rates. In this context, the glycans observed at the surface of cancer cells are presented as efficient tumor cell markers. These carbohydrate structures can be recognized by lectins which can act as decoders of the glycocode. The application of plant lectins as tools for diagnosis/treatment of breast cancer encompasses the detection and sorting of glycans found in healthy and malignant cells. Here, we present an overview of the most recent studies in this field, demonstrating the potential of lectins as: mapping agents to detect differentially expressed glycans in breast cancer, as histochemistry/cytochemistry analysis agents, in lectin arrays, immobilized in chromatographic matrices, in drug delivery, and as biosensing agents. In addition, we describe lectins that present antiproliferative effects by themselves and/or in conjunction with other drugs in a synergistic effect.

Coacervate-mediated novel pancreatic cancer drug Aleuria Aurantia lectin delivery for augmented anticancer therapy

Background

Pancreatic cancer, one of the cancers with the highest mortality rate, has very limited clinical treatment. Cancer cells express abnormal glycans on the surface, and some lectins with a high affinity for the glycans induce apoptosis in cancer. In this study, the efficacy of Aleuria Aurantia lectin (AAL) for the treatment of pancreatic cancer was evaluated and the efficacy improvement through AAL delivery with mPEGylated coacervate (mPEG-Coa) was investigated.

Methods

AAL was treated with pancreatic cancer cells, PANC-1, and the expression level of caspase-3 and subsequent apoptosis was analyzed. In particular, the anticancer efficacy of AAL was compared with that of concanavalin A, one of the representative anticancer lectins. Then, methoxypolyethylene glycol-poly(ethylene arginylaspartate diglyceride), a polycation, was synthesized, and an mPEG-Coa complex was prepared with polyanion heparin. The AAL was incorporated into the mPEG-Coa and the release kinetics of the AAL from the mPEG-Coa and the cargo protection capacity of the mPEG-Coa were evaluated. Finally, improved anticancer ability through Coa-mediated AAL delivery was assessed.

Results

These results indicated that AAL is a potential effective pancreatic cancer treatment. Moreover, mPEG-Coa rapidly released AAL at pH 6.5, an acidic condition in the cancer microenvironment. The initial rapid release of AAL effectively suppressed pancreatic cancer cells, and the continuous supply of AAL through the Coa transporter effectively inhibited proliferation recurrence of cancer cells.

Conclusion

AAL is a potential novel drug for the treatment of pancreatic cancer therapeutic agent. In addition, a continuous supply of drugs above the therapeutic threshold using mPEG-Coa could improve therapeutic efficacy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40824-022-00282-6.

In-Vitro Growth Kinetics of Mesenchymal Stem Cells in Cytotoxicity Tests Using Low-Diluted Viscum Album

INTRODUCTION

 The use of mesenchymal stem cells (MSC) in cytotoxicity tests is an in-vitro alternative model for predicting initial doses. Homeopathic medicines may stimulate the immune system to combat a pathology effectively and have been used for over two centuries. Viscum album (VA) extracts are widely used in the treatment of cancer, due to their immunomodulatory, cytotoxic and pro-apoptotic properties.

OBJECTIVE

 This study aimed to evaluate the in-vitro growth kinetics of canine MSC in relation to cytotoxicity, cell differentiation and expression of pluripotentiality markers, using a VA preparation at the D1D2 (1×10^-1, 1×10^-2 potency (VAD1D2).

METHODS

 MSC were obtained from adipose tissue sampled from a healthy dog that was undergoing an elective veterinary procedure and with its owner's permission. The experiments were performed in three groups: MSC treated with VAD1D2 or diluent or untreated (control). The cytotoxicity was evaluated by MTT assay. The differentiation was induced in three lineages, and apoptotic cell labeling was performed by an Annexin-V test.

RESULTS

 At the concentration of 10 μL/mL of VA, the number of cells after in-vitro culture was maintained when compared with the control (untreated) group. A significant and gradual decrease in cell viability was recorded as VA concentrations increased. The apoptosis analysis showed that VA at 20 μL/mL presented absolute percentages of initial apoptosis twice as high as at 10 μL/mL, which was similar to the control (untreated group).

CONCLUSION

 The results suggest that the use of efficient methods to assess the in-vitro cytotoxicity of VA-based homeopathic medicines using MSC lineages may predict the potential action at different concentrations. These findings demonstrated that VAD1D2 interferes with canine MSC growth kinetics.

The accurate prediction and characterization of cancerlectin by a combined machine learning and GO analysis

Cancerlectins, lectins linked to tumor progression, have become the focus of cancer therapy research for their carbohydrate-binding specificity. However, the specific characterization for cancerlectins involved in tumor progression is still unclear. By taking advantage of the g-gap tripeptide and tetrapeptide composition feature descriptors, we increased the accuracy of the classification model of cancerlectin and lectin to 98.54% and 95.38%, respectively. About 36 cancerlectin and 135 lectin features were selected for functional characterization by P/N feature ranking method, which particularly selects the features in positive samples. The specific protein domains of cancerlectins are found to be p-GalNAc-T, crystal and annexin by comparing with lectins through the exclusion method. Moreover, the combined GO analysis showed that the conserved cation binding sites of cancerlectin specific domains are covered by selected feature peptides, suggesting that the capability of cation binding, critical for enzyme activity and stability, could be the key characteristic of cancerlectins in tumor progression. These results will help to identify potential cancerlectin and provide clues for mechanism study of cancerlectin in tumor progression.

Identification of Cancerlectins By Using Cascade Linear Discriminant Analysis and Optimal g-gap Tripeptide Composition

Background:

Lectins are a diverse group of glycoproteins or glycoconjugate proteins that can be extracted from plants, invertebrates and higher animals. Cancerlectins, a kind of lectins, which play a key role in the process of tumor cells interacting with each other and are being employed as therapeutic agents. A full understanding of cancerlectins is significant because it provides a tool for the future direction of cancer therapy.

Objective:

To develop an accurate and practically useful timesaving tool to identify cancerlectins. A novel sequence-based method is proposed along with a correlative webserver to access the proposed tool.

Methods:

Firstly, protein features were extracted in a newly feature building way termed, g-gap tripeptide composition. After which a proposed cascade linear discriminant analysis (Cascade LDA) is used to alleviate the high dimensional difficulties with the Analysis Of Variance (ANOVA) as a feature importance criterion. Finally, Support Vector Machine (SVM) is used as the classifier to identify cancerlectins.

Results:

The proposed method achieved an accuracy of 91.34% with sensitivity of 89.89%, specificity of 92.48% and an 0.8318 Mathew’s correlation coefficient based on only 13 fusion features in jackknife cross validation, the result of which is superior to other published methods in this domain.

Conclusion:

In this study, a new method based only on primary structure of protein is proposed and experimental results show that it could be a promising tool to identify cancerlectins. An openaccess webserver is made available in this work to facilitate other related works.

Biological activity of mistletoe: in vitro and in vivo studies and mechanisms of action

Mistletoe has been used as treatment of many diseases in traditional and folk medicine. To date, anticancer, immunomodulatory, cardiac, antidiabetic, hepatoprotective, neuropharmacological, antibacterial and antifungal properties of mistletoe extracts have been studied the most. In this review, we summarized in vitro and in vivo studies on the pharmacological activity of Viscum species. Furthermore, we proposed the possible mechanisms of action of this herb, which might include many signalling pathways. Mistletoe could regulate either similar or different targets in various pathways that act on membrane receptors, enzymes, ion channels, transporter proteins and transcriptional targets. Still, pharmacological activities of mistletoe have been investigated mainly for crude extracts. It is a new field for scientists to determined which chemical compounds are responsible for the individual biological activities of mistletoe and how these activities are achieved. As a result, mistletoe might become a source of new complementary therapies supporting the treatment of many diseases.

Plant-Derived Lectins as Potential Cancer Therapeutics and Diagnostic Tools

Cancer remains a global health challenge, with high morbidity and mortality, despite the recent advances in diagnosis and treatment. Multiple compounds assessed as novel potential anticancer drugs derive from natural sources, including microorganisms, plants, and animals. Lectins, a group of highly diverse proteins of nonimmune origin with carbohydrate-binding abilities, have been detected in virtually all kingdoms of life. These proteins can interact with free and/or cell surface oligosaccharides and might differentially bind cancer cells, since malignant transformation is tightly associated with altered cell surface glycans. Therefore, lectins could represent a valuable tool for cancer diagnosis and be developed as anticancer therapeutics. Indeed, several plant lectins exert cytotoxic effects mainly by inducing apoptotic and autophagic pathways in malignant cells. This review summarizes the current knowledge regarding the basis for the use of lectins in cancer diagnosis and therapy, providing a few examples of plant-derived carbohydrate-binding proteins with demonstrated antitumor effects.

Identification of Cancerlectins Using Support Vector Machines With Fusion of G-Gap Dipeptide

The cancerlectin plays an important role in the initiation, survival, growth, metastasis, and spread of cancer. Therefore, to study the function of cancerlectin is greatly significant because it can help to identify tumor markers and tumor prevention, treatment, and prognosis. However, plenty of studies have generated a large amount of protein data. Traditional prediction methods have been unable to meet the needs of analysis. Developing powerful computational models based on these data to discriminate cancerlectins and non-cancerlectins on a large scale has been treated as one of the most important topics. In this study, we developed a feature extraction method to identify cancerlectins based on fusion of g-gap dipeptides. The analysis of variance was used to select the optimal feature set and a support vector machine was used to classify the data. The rigorous nested 10-fold cross-validation results, demonstrated that our method obtained the prediction accuracy of 83.91% and sensitivity of 83.15%. At the same time, in order to evaluate the performance of the classification model constructed in this work, we constructed a new data set. The prediction accuracy of the new data set reaches 83.3%. Experimental results show that the performance of our method is better than the state-of-the-art methods.

Tepary Bean (Phaseolus acutifolius) Lectins Induce Apoptosis and Cell Arrest in G0/G1 by P53(Ser46) Phosphorylation in Colon Cancer Cells

A Tepary bean lectin fraction (TBLF) has been studied because it exhibits differential cytotoxic and anticancer effects on colon cancer. The present work focuses on the evaluation of the apoptotic mechanism of action on colon cancer cells. Initially, lethal concentrations (LC₅₀) were obtained for the three studied cell lines (HT-29, RKO and SW-480). HT-29 showed the highest LC₅₀, 10 and 100 times higher than that of RKO and SW-480 cells, respectively. Apoptosis was evaluated by flow cytometry, where HT-29 cells showed the highest levels of early and total apoptosis, caspases activity was confirmed and necrosis was discarded. The effect on cell cycle arrest was shown in the G0/G1 phase. Specific apoptosis-related gene expression was determined, where an increase in p53 and a decrease in Bcl-2 were observed. Expression of p53 gene showed the maximum level at 8 h with an important decrease at 12 and 24 h, also the phosphorylated p53(ser46) increased at 8 h. Our results show that TBLF induces apoptosis in colon cancer cells by p-p53(ser46) involvement. Further studies will focus on studying the specific signal transduction pathway.

lncRNA CCAT2 Enhanced Resistance of Glioma Cells Against Chemodrugs by Disturbing the Normal Function of miR-424

Background

Aggressive metastasis of tumor cells assumed a constructive role in strengthening chemoresistance of tumors, so this investigation was intended to elucidate if lncRNA CCAT2 sponging downstream miR-424 regulated chemotolerance of glioma cells by boosting metastasis of glioma cells.

Methods

One hundred and twenty-eight pairs of glioma tissues and corresponding adjacent tissues were resected from glioma patients during their operation, and we also purchased a series of glioma cell lines, including U251, U87, A172 and SHG44. Furthermore, pcDNA3.1-CCAT2, si-CCAT2, miR-424 mimic and miR-424 inhibitor were transfected into SHG44 and U251 cell lines, so as to evaluate impacts of CCAT2 and miR-424 on chemosensitivity of the glioma cells. Besides, proliferation, invasion and metastasis of the cells were determined through the implementation of colony formation assay, transwell assay and scratch assay.

Results

Glioma tissues and cells were monitored with higher CCAT2 expression and lower miR-424 expression than adjacent normal tissues and NHA cell line (P<0.05). Among the glioma cell lines, the SHG44 cell line showed the strongest resistance against teniposide, temozolomide and cisplatin (P<0.05), whereas the U251 cell line was more sensitive to teniposide, temozolomide, vincristine and cisplatin than any other cell line (P<0.05). Besides, pcDNA3.1-CCAT2 and miR-424 inhibitor could enhance tolerance of glioma cell lines against drugs (P<0.05). Moreover, in-vitro transfection of si-CCAT2 and miR-424 mimic could significantly retard proliferation, invasion and migration of SHG44 and U251 cells (P<0.05), and CCAT2 was found to negatively regulate miR-424 expression by sponging it (P<0.05). In addition, CHK1 was deemed as the molecule targeted by upstream miR-424, and its overexpression can changeover the effects of miR-424 mimic on proliferation and metastasis of SHG44 and U251 cells.

Conclusion

lncRNA CCAT2/miR-424/Chk1 axis might serve as a promising target for improving chemotherapeutic efficacies in glioma treatment.

Structure-function and application of plant lectins in disease biology and immunity

Lectins are proteins with a high degree of stereospecificity to recognize various sugar structures and form reversible linkages upon interaction with glyco-conjugate complexes. These are abundantly found in plants, animals and many other species and are known to agglutinate various blood groups of erythrocytes. Further, due to the unique carbohydrate recognition property, lectins have been extensively used in many biological functions that make use of protein-carbohydrate recognition like detection, isolation and characterization of glycoconjugates, histochemistry of cells and tissues, tumor cell recognition and many more. In this review, we have summarized the immunomodulatory effects of plant lectins and their effects against diseases, including antimicrobial action. We found that many plant lectins mediate its microbicidal activity by triggering host immune responses that result in the release of several cytokines followed by activation of effector mechanism. Moreover, certain lectins also enhance the phagocytic activity of macrophages during microbial infections. Lectins along with heat killed microbes can act as vaccine to provide long term protection from deadly microbes. Hence, lectin based therapy can be used as a better substitute to fight microbial diseases efficiently in future.

A Two-Step Feature Selection Method to Predict Cancerlectins by Multiview Features and Synthetic Minority Oversampling Technique

Cancerlectins have an inhibitory effect on the growth of cancer cells and are currently being employed as therapeutic agents. The accurate identification of the cancerlectins should provide insight into the molecular mechanisms of cancers. In this study, a new computational method based on the RF (Random Forest) algorithm is proposed for further improving the performance of identifying cancerlectins. Hybrid feature space before feature selection is developed by combining different individual feature spaces, CTD (Composition, Transition, and Distribution), PseAAC (Pseudo Amino Acid Composition), PSSM (Position-Specific Scoring Matrix), and disorder. The SMOTE (Synthetic Minority Oversampling Technique) is applied to solve the imbalanced data problem. To reduce feature redundancy and computation complexity, we propose a two-step feature selection process to select informative features. A 5-fold cross-validation technique is used for the evaluation of various prediction strategies. The proposed method achieves a sensitivity of 0.779, a specificity of 0.717, an accuracy of 0.748, and an MCC (Matthew's Correlation Coefficient) of 0.497. The prediction results are also compared with other existing methods on the same dataset using 5-fold cross-validation. The comparison results demonstrate the high effectiveness of our method for predicting cancerlectins.

Telomerase Inhibitors from Natural Products and Their Anticancer Potential

Telomeres and telomerase are nowadays exploring traits on targets for anticancer therapy. Telomerase is a unique reverse transcriptase enzyme, considered as a primary factor in almost all cancer cells, which is mainly responsible to regulate the telomere length. Hence, telomerase ensures the indefinite cell proliferation during malignancy—a hallmark of cancer—and this distinctive feature has provided telomerase as the preferred target for drug development in cancer therapy. Deactivation of telomerase and telomere destabilization by natural products provides an opening to succeed new targets for cancer therapy. This review aims to provide a fundamental knowledge for research on telomere, working regulation of telomerase and its various binding proteins to inhibit the telomere/telomerase complex. In addition, the review summarizes the inhibitors of the enzyme catalytic subunit and RNA component, natural products that target telomeres, and suppression of transcriptional and post-transcriptional levels. This extensive understanding of telomerase biology will provide indispensable information for enhancing the efficiency of rational anti-cancer drug design.

Phaseolus acutifolius Lectin Fractions Exhibit Apoptotic Effects on Colon Cancer: Preclinical Studies Using Dimethilhydrazine or Azoxi-Methane as Cancer Induction Agents

Phaseolus acutifolius (Tepary bean) lectins have been studied as cytotoxic molecules on colon cancer cells. The toxicological profile of a Tepary bean lectin fraction (TBLF) has shown low toxicity in experimental animals; exhibiting anti-nutritional effects such as a reduction in body weight gain and a decrease in food intake when using a dose of 50 mg/kg on alternate days for six weeks. Taking this information into account, the focus of this work was to evaluate the effect of the TBLF on colon cancer using 1,2-dimethylhydrazine (DMH) or azoxy-methane/dextran sodium sulfate (AOM/DSS) as colon cancer inductors. Rats were treated with DMH or AOM/DSS and then administered with TBFL (50 mg/kg) for six weeks. TBLF significantly decreased early tumorigenesis triggered by DMH by 70%, but without any evidence of an apoptotic effect. In an independent experiment, AOM/DSS was used to generate aberrant cryptic foci, which decreased by 50% after TBLF treatment. TBLF exhibited antiproliferative and proapoptotic effects related to a decrease of the signal transduction pathway protein Akt in its activated form and an increase of caspase 3 activity, but not to p53 activation. Further studies will deepen our knowledge of specific apoptosis pathways and cellular stress processes such as oxidative damage.

Plant Lectins Targeting O-Glycans at the Cell Surface as Tools for Cancer Diagnosis, Prognosis and Therapy

Aberrant O-glycans expressed at the surface of cancer cells consist of membrane-tethered glycoproteins (T and Tn antigens) and glycolipids (Lewis a, Lewis x and Forssman antigens). All of these O-glycans have been identified as glyco-markers of interest for the diagnosis and the prognosis of cancer diseases. These epitopes are specifically detected using T/Tn-specific lectins isolated from various plants such as jacalin from Artocarpus integrifola, and fungi such as the Agaricus bisporus lectin. These lectins accommodate T/Tn antigens at the monosaccharide-binding site; residues located in the surrounding extended binding-site of the lectins often participate in the binding of more extended epitopes. Depending on the shape and size of the extended carbohydrate-binding site, their fine sugar-binding specificity towards complex O-glycans readily differs from one lectin to another, resulting in a great diversity in their sugar-recognition capacity. T/Tn-specific lectins have been extensively used for the histochemical detection of cancer cells in biopsies and for the follow up of the cancer progression and evolution. T/Tn-specific lectins also induce a caspase-dependent apoptosis in cancer cells, often associated with a more or less severe inhibition of proliferation. Moreover, they provide another potential source of molecules adapted to the building of photosensitizer-conjugates allowing a specific targeting to cancer cells, for the photodynamic treatment of tumors.

Targeted apoptosis in ovarian cancer cells through mitochondrial dysfunction in response to Sambucus nigra agglutinin

Ovarian carcinoma (OC) patients encounter the severe challenge of clinical management owing to lack of screening measures, chemoresistance and finally dearth of non-toxic therapeutics. Cancer cells deploy various defense strategies to sustain the tumor microenvironment, among which deregulated apoptosis remains a versatile promoter of cancer progression. Although recent research has focused on identifying agents capable of inducing apoptosis in cancer cells, yet molecules efficiently breaching their survival advantage are yet to be classified. Here we identify lectin, Sambucus nigra agglutinin (SNA) to exhibit selectivity towards identifying OC by virtue of its specific recognition of α-2, 6-linked sialic acids. Superficial binding of SNA to the OC cells confirm the hyper-sialylated status of the disease. Further, SNA activates the signaling pathways of AKT and ERK1/2, which eventually promotes de-phosphorylation of dynamin-related protein-1 (Drp-1). Upon its translocation to the mitochondrial fission loci Drp-1 mediates the central role of switch in the mitochondrial phenotype to attain fragmented morphology. We confirmed mitochondrial outer membrane permeabilization resulting in ROS generation and cytochrome-c release into the cytosol. SNA response resulted in an allied shift of the bioenergetics profile from Warburg phenotype to elevated mitochondrial oxidative phosphorylation, altogether highlighting the involvement of mitochondrial dysfunction in restraining cancer progression. Inability to replenish the SNA-induced energy crunch of the proliferating cancer cells on the event of perturbed respiratory outcome resulted in cell cycle arrest before G2/M phase. Our findings position SNA at a crucial juncture where it proves to be a promising candidate for impeding progression of OC. Altogether we unveil the novel aspect of identifying natural molecules harboring the inherent capability of targeting mitochondrial structural dynamics, to hold the future for developing non-toxic therapeutics for treating OC.

Transcriptomic and proteomic insight into the effects of a defined European mistletoe extract in Ewing sarcoma cells reveals cellular stress responses

BACKGROUND

The hydrophobic triterpenes, oleanolic and betulinic acid as well as the hydrophilic mistletoe lectins and viscotoxins possess anticancer properties. They do all occur in combination in European mistletoe (Viscum album L.). Commercial Viscum album L. extracts are aqueous, excluding the insoluble triterpenes. We have previously shown that mistletoe lectins and triterpene acids are effective against Ewing sarcoma in vitro, ex vivo and in vivo.

METHODS

We recreated a total mistletoe effect (viscumTT) by combining an aqueous extract (viscum) and a triterpene extract (TT) solubilised with cyclodextrins and analysed the effects of viscumTT and the single extracts on TC-71 Ewing sarcoma cells in vitro by transcriptomic and proteomic profiling.

RESULTS

Treatment with the extracts strongly impacted Ewing sarcoma cell gene and protein expression. Apoptosis-associated and stress-activated genes were upregulated, proteasomal protein abundance enhanced and ribosomal and spliceosomal proteins downregulated. The mechanism of action of viscum, TT and viscumTT in TC-71 and MHH-ES-1 cells suggests the involvement of the unfolded protein response. While viscum and viscumTT extract treatment indicate response to oxidative stress and activation of stress-mediated MAPK signalling, TT extract treatment suggests the involvement of TLR signalling and autophagy.

CONCLUSIONS

Since the combinatory extract viscumTT exerts highly effective pro-apoptotic effects on Ewing sarcoma cells in vitro, this phytopolychemotherapy could be a promising adjuvant therapeutic option for paediatric patients with Ewing sarcoma.

Harnessing benefit from targeting tumor associated carbohydrate antigens

Integrating additive or synergistic antitumor effects that focus on distinct elements of tumor biology are the most rational strategies for cancer treatment. Treatments for breast cancer have increased overall survival, but remain limited by lack of efficacy in a subset of breast cancer patients. The real challenge is to define what elements of tumor biology make the most sense to be integrated. An emerging strategy is to consider a systems biology approach to impact multiple interactions in networks as compare with hitting a specific protein-protein interaction target. In this review, we consider how targeting tumor associated carbohydrate antigens (TACA) that are fundamental to signal pathways might be tailored to harness benefit from combination therapy of sustained immunity with chemotherapy. An approach we are developing makes use of a carbohydrate mimetic peptide (CMP) to induce polyspecific antibodies, which by their nature have numerous on and off target effects. Linking multi-target TACA recognition with mechanisms affecting tumor growth in the context of network heterogeneity and concepts of immune surveillance to tumor cells and the type of breast cancer patients that would benefit from such an approach provides a novel integrative treatment.

Agglutinin isolated from Arisema heterophyllum Blume induces apoptosis and autophagy in A549 cells through inhibiting PI3K/Akt pathway and inducing ER stress

Arisaema heterophyllum Blume is one of the three medicinal plants known as traditional Chinese medicine Rhizoma Arisaematis (RA). RA has been popularly used to treat patients with convulsions, inflammation, and cancer for a long time. However, the underlying mechanisms for RA effects are still unclear. The present study was designed to determine the cytotoxicity of agglutinin isolated from Arisema heterophyllum Blume (AHA) and explore the possible mechanisms in human non-small-cell lung cancer A549 cells. AHA with purity up to 95% was isolated and purified from Arisaema heterophyllum Blume using hydrophobic interaction chromatography. AHA dose-dependently inhibited the proliferation of A549 cells and induced G₁ phase cell cycle arrest. AHA induced apoptosis by up-regulating pro-apoptotic Bax, decreasing anti-apoptotic Bcl-2, and activating caspase-9 and caspase-3. In A549 cells treated with AHA, the PI3K/Akt pathway was inhibited. Furthermore, AHA induced increase in the levels of ER stress markers such as phosphorylated eukaryotic initiation factor 2α (p-eIF2α), C/EBP-homologous protein (CHOP), inositol-requiring enzyme 1α (IRE1α), and phosphorylated c-Jun NH₂-terminal kinase (p-JNK). AHA also induced autophagy in A549 cells. Staining of acidic vesicular organelles (AVOs) and increase in the levels of LC3II and ATG7 were observed in AHA-treated cells. These findings suggested that AHA might be one of the active components with anti-cancer effects in Arisaema heterophyllum Blume. In conclusion, cytotoxicity of AHA on cancer cells might be related to its effects on apoptosis and autophagy through inhibition of PI3K/Akt pathway and induction of ER stress.

Viscolin Inhibits In Vitro Smooth Muscle Cell Proliferation and Migration and Neointimal Hyperplasia In Vivo

Viscolin, an extract of Viscum coloratum, has anti-inflammatory and anti-proliferative properties against harmful stimuli. The aim of the study was to examine the anti-proliferative effects of viscolin on platelet derived growth factor-BB (PDGF)-treated human aortic smooth muscle cells (HASMCs) and identify the underlying mechanism responsible for these effects. Viscolin reduced the PDGF-BB-induced HASMC proliferation and migration in vitro; it also arrested HASMCs in the G0/G1 phase by decreasing the protein expression of Cyclin D1, CDK2, Cyclin E, CDK4, and p21^Cip1 as detected by Western blot analysis. These effects may be mediated by reduced PDGF-induced phosphorylation of ERK1/2, JNK, and P38, but not AKT as well as inhibition of PDGF-mediated nuclear factor (NF)-κB p65 and activator protein 1 (AP-1)/c-fos activation. Furthermore, viscolin pre-treatment significantly reduced neointimal hyperplasia of an endothelial-denuded femoral artery in vivo. Taken together, viscolin attenuated PDGF–BB-induced HASMC proliferation in vitro and reduced neointimal hyperplasia in vivo. Thus, viscolin may represent a therapeutic candidate for the prevention and treatment of vascular proliferative diseases.

High-Dose Viscum album Extract Treatment in the Prevention of Recurrent Bladder Cancer: A Retrospective Case Series

INTRODUCTION

Viscum album extract (European mistletoe), containing immuno-active compounds with dose-dependent cytotoxic activity, is being used as an adjuvant cancer treatment in Europe. Few studies have yet been done with high-dose, fever-inducing Viscum album treatment.

OBJECTIVE

To explore whether subcutaneous injections of high-dose Viscum album have a preventive effect on risk of recurrence of bladder cancer.

METHODS

We retrospectively analyzed the case records of patients with resectable bladder cancer who underwent initiation of high-dose Viscum album treatment at our clinic between January 2006 and December 2012.

MAIN OUTCOME MEASURES

We calculated tumor recurrence and progression risk and explored case records to assess whether treatment had a likely, possible, or unlikely beneficial effect.

RESULTS

Eight patients were identified, 7 of whom had nonmuscle-invasive bladder cancer and 1 with muscle-invasive cancer. Four patients had frequently recurring tumors before treatment. Among the 8 patients, 28 episodes of recurrence were observed. Median tumor-free follow-up duration was 48.5 months. High-dose Viscum album showed a possible beneficial effect in 5 of 8 patients, could not be assessed in 2 patients, and had an uncertain effect in 1 patient. No tumor progression was observed. Treatment was generally well tolerated and no patient stopped treatment because of side effects.

CONCLUSION

High-dose Viscum album treatment may have interrupted frequently recurring tumors in individual patients with recurrent bladder cancer. Prospective studies are needed to assess whether this treatment offers an additional, bladder-sparing preventive option for patients with intermediate- to high-risk nonmuscle-invasive bladder cancer.. Treatment was generally well tolerated and no patient stopped treatment because of side effects.

Jacalin-Activated Macrophages Exhibit an Antitumor Phenotype

Tumor-associated macrophages (TAMs) have an ambiguous and complex role in the carcinogenic process, since these cells can be polarized into different phenotypes (proinflammatory, antitumor cells or anti-inflammatory, protumor cells) by the tumor microenvironment. Given that the interactions between tumor cells and TAMs involve several players, a better understanding of the function and regulation of TAMs is crucial to interfere with their differentiation in attempts to skew TAM polarization into cells with a proinflammatory antitumor phenotype. In this study, we investigated the modulation of macrophage tumoricidal activities by the lectin jacalin. Jacalin bound to macrophage surface and induced the expression and/or release of mainly proinflammatory cytokines via NF-κB signaling, as well as increased iNOS mRNA expression, suggesting that the lectin polarizes macrophages toward the antitumor phenotype. Therefore, tumoricidal activities of jacalin-stimulated macrophages were evaluated. High rates of tumor cell (human colon, HT-29, and breast, MCF-7, cells) apoptosis were observed upon incubation with supernatants from jacalin-stimulated macrophages. Taken together, these results indicate that jacalin, by exerting a proinflammatory activity, can direct macrophages to an antitumor phenotype. Deep knowledge of the regulation of TAM functions is essential for the development of innovative anticancer strategies.

European Viscum album: a potent phytotherapeutic agent with multifarious phytochemicals, pharmacological properties and clinical evidence

Viscum albumL. or European mistletoe (Loranthaceae), a semi-parasitic shrub, has been used as a traditional medicine in Europe for centuries to treat various diseases like cancer, cardiovascular disorder, epilepsy, infertility, hypertension and arthritis.

Enhanced anti-oxidative effect of fermented Korean mistletoe is originated from an increase in the contents of caffeic acid and lyoniresinol

The crude enzyme extract derived from Aspergillus kawachii increased the anti-oxidants, caffeic acid and lyoniresinol, in Korean mistletoe.

Predicting cancerlectins by the optimal g-gap dipeptides

The cancerlectin plays a key role in the process of tumor cell differentiation. Thus, to fully understand the function of cancerlectin is significant because it sheds light on the future direction for the cancer therapy. However, the traditional wet-experimental methods were money- and time-consuming. It is highly desirable to develop an effective and efficient computational tool to identify cancerlectins. In this study, we developed a sequence-based method to discriminate between cancerlectins and non-cancerlectins. The analysis of variance (ANOVA) was used to choose the optimal feature set derived from the g-gap dipeptide composition. The jackknife cross-validated results showed that the proposed method achieved the accuracy of 75.19%, which is superior to other published methods. For the convenience of other researchers, an online web-server CaLecPred was established and can be freely accessed from the website http://lin.uestc.edu.cn/server/CalecPred. We believe that the CaLecPred is a powerful tool to study cancerlectins and to guide the related experimental validations.

Development and Applications of Lectins as Biological Tools in Biomedical Research

As a new and burgeoning area following genomics and proteomics, glycomics has become a hot issue due to its pivotal roles in many physiological and pathological processes. Glycans are much more complicated than genes or proteins since glycans are highly branched and dynamic. Antibodies and lectins are the two major molecular tools applied for glycan profiling. Though the study of antibodies and lectins started at almost the same time in 1880s, lectins gained much less attention than the antibodies until recent decades when the importance and difficulties of glycomics were realized. The present review summarizes the discovery history of lectins and their biological functions with a special emphasis on their various applications as biological tools. Both older techniques that had been developed in the last century and new technologies developed in recent years, especially lectin microarrays and lectin-based biosensors, are included in this account.

The inhibitory effect of PIK-75 on inflammatory mediator response induced by hydrogen peroxide in feline esophageal epithelial cells

Isoform-selective inhibitors of phosphoinositide 3-kinase (PI3K) activation have an anti-inflammatory effect by reducing proinflammatory cytokines. Cultured feline esophageal epithelial cells (EEC) of passages 3~4 were treated with hydrogen peroxide and PIK-75. The cell viability was measured by a MTT incorporation assay. The distribution of PI3K isoforms, p-Akt, IL-1β, and IL-8 was inferred from Western blots. The release of IL-6 was determined by ELISA. The cell morphology was not considerably different from nontreated cells if the cells were pretreated with PIK-75 and treated with 300 μM hydrogen peroxide. The density of p110α of PI3K was increased, but that of other types was not affected after the treatment with hydrogen peroxide. The density of p-Akt, when the cells were exposed to PIK-75 and hydrogen peroxide, was diminished dose dependently more than that of hydrogen peroxide treatment only. The decrease of p-Akt showed an inhibition of PI3K by PIK-75. PIK-75 dose dependently reduced the expression of IL-1β, IL-8, and the level of IL-6 compared with hydrogen peroxide treatment only. These results suggest evidence that p110α mediates esophageal inflammation and that PIK-75 has an anti-inflammatory effect by reducing proinflammatory cytokines on feline esophageal epithelial cultured cells.

Synergistic anticancer effects of lectin and doxorubicin in breast cancer cells

We studied the effects, either combined or alone, of lectin from Korean mistletoe (Viscum album var. coloratum agglutinin, VCA) and doxorubicin (DOX) in MCF-7 (estrogen receptor-positive) and MDA-MB231 (estrogen receptor-negative) human breast cancer cells. When VCA and DOX were combined, a strong synergistic effect was shown in cell growth inhibition, compared to VCA or DOX treatment alone. In quantitative apoptosis studies analyzed by flow cytometry, a combination of two agents showed an increase in apoptosis in both cells, compared to agents alone. Also, pro-apoptotic proteins including Bax, Bik, and Puma were increased in both cells, and the survival factor Bcl-2 was inhibited in MCF-7 cells when drugs were combined. Furthermore, VCA combined with DOX mediated S phase arrest, accompanied with a decrease of cell number at G0/G1 phase. This suggests that VCA and DOX combination may possibly lead to a novel strategy for the treatment of breast cancer.

Intratumoral Mistletoe (Viscum album L) Therapy in Patients With Unresectable Pancreas Carcinoma: A Retrospective Analysis

Pancreatic carcinoma remains one of the main causes for cancer-related death. Intratumoral application of anticancer agents is discussed as a promising method for solid tumors such as pancreatic cancer. Endoscopic ultrasound provides a good tool to examine and treat the pancreas. European mistletoe (Viscum album L) is a phytotherapeutic commonly used in integrative oncology in Central Europe. Its complementary use seeks to induce immunostimulation and antitumoral effects as well as alleviate chemotherapeutic side effects. Intratumoral mistletoe application has induced local tumor response in various cancer entities. This off-label use needs to be validated carefully in terms of safety and benefits. Here we report on 39 patients with advanced, inoperable pancreatic cancer, who received in total 223 intratumoral applications of mistletoe, endoscopic ultrasound guided or under transabdominal ultrasound control. No severe procedure-related events were reported. Adverse drug reactions were mainly increased body temperature or fever in 14% and 11% of the applications, respectively. Other adverse drug reactions, such as pain or nausea, occurred in less than 7% of the procedures. No severe adverse drug reaction was recorded. Patients received standard first- and second-line chemotherapy and underwent adequate palliative surgical interventions as well as additive subcutaneous and partly intravenous mistletoe application. A median survival of 11 months was observed for all patients, or 11.8 and 8.3 months for stages III and IV, respectively. Due to the multimodal therapeutic setting and the lack of a control group, the effect of intratumoral mistletoe administration alone remains unclear. This retrospective analysis suggests that intratumoral-applicated mistletoe might contribute to improve survival of patients with pancreatic cancer. In conclusion, the application is feasible and safe, and its efficacy should be evaluated in a randomized controlled trial.

Cancer Prevention and Therapy: Integrating Traditional Korean Medicine Into Modern Cancer Care

In spite of billions of dollars spent on cancer research each year, overall cancer incidence and cancer survival has not changed significantly in the last half century. Instead, the recent projection from the World Health Organization suggests that global cancer incidence and death is expected to double within the next decade. This requires an "out of the box" thinking approach. While traditional medicine used for thousands of years is safe and affordable, its efficacy and mechanism of action are not fully reported. Demonstrating that traditional medicine is efficacious and how it works can provide a "bed to bench" and "bench to bed" back approach toward prevention and treatment of cancer. This current review is an attempt to describe the contributions of traditional Korean medicine (TKM) to modern medicine and, in particular, cancer treatment. TKM suggests that cancer is an outcome of an imbalance of body, mind, and spirit; thus, it requires a multimodal treatment approach that involves lifestyle modification, herbal prescription, acupuncture, moxibustion, traditional exercise, and meditation to restore the balance. Old wisdoms in combination with modern science can find a new way to deal with the "emperor of all maladies."

Korean mistletoe lectin regulates self-renewal of placenta-derived mesenchymal stem cells via autophagic mechanisms

OBJECTIVES

The balance between survival and death is a key point for regulation of physiology of stem cells. Recently, applications of natural products to enhance efficiencies in culturing and differentiation of stem cells are increasing. Korean mistletoe lectin (Viscum album L. var. coloratum agglutinin, VCA) has been known to be toxic to some cancer cells, but it is still unclear whether VCA has a cytotoxic or indeed a proliferative effect on mesenchymal stem cells (MSCs). Here, we have compared effects of VCA in naïve placenta-derived stem cells (PDSCs), immortalized PDSCs and cancer cells (HepG2), and analysed their mechanisms.

MATERIALS AND METHODS

MTT assay was performed to analyse effects of VCA on naïve PDSCs, immortalized PDSCs and HepG2. FACS, ROS, caspase-3 assay, western blotting and immunofluorescence were performed to detect signalling events involved in self-renewal of the above cell types.

RESULTS

VCA had cancer cell-specific toxicity to HepG2 cells even with low concentrations of VCA (1-5 pg/ml), toxicity was observed to immortalized PDSCs and HepG2s, while proliferation of naïve PDSCs was significantly increased (P < 0.05). ROS production by VCA treatment in naïve PDSCs was significantly lower compared to controls (P < 0.05). Furthermore, autophagy was activated in naïve PDSCs treated with VCA through increase in type II LC3 and decrease in phosphorylated mTOR.

CONCLUSIONS

VCA can promote MSC proliferation through an activated autophagic mechanism.

Fermented mistletoe extract as a multimodal antitumoral agent in gliomas

In Europe, commercially available extracts from the white-berry mistletoe (Viscum album L.) are widely used as a complementary cancer therapy. Mistletoe lectins have been identified as main active components and exhibit cytotoxic effects as well as immunomodulatory activity. Since it is still not elucidated in detail how mistle toe extracts such as ISCADOR communicate their effects, we analyzed the mechanisms that might be responsible for their antitumoral function on a molecular and functional level. ISCADOR-treated glioblastoma (GBM) cells down-regulate central genes involved in glioblastoma progression and malignancy such as the cytokine TGF-β and matrix-metalloproteinases. Using in vitro glioblastoma/immune cell co-cultivation assays as well as measurement of cell migration and invasion, we could demonstrate that in glioblastoma cells, lectin-rich ISCADOR M and ISCADOR Q significantly enforce NK-cell-mediated GBM cell lysis. Beside its immune stimulatory effect, ISCADOR reduces the migratory and invasive potential of glioblastoma cells. In a syngeneic as well as in a xenograft glioblastoma mouse model, both pretreatment of tumor cells and intratumoral therapy of subcutaneously growing glioblastoma cells with ISCADOR Q showed delayed tumor growth. In conclusion, ISCADOR Q, showing multiple positive effects in the treatment of glioblastoma, may be a candidate for concomitant treatment of this cancer.

Apoptosis of K562 leukemia cells by Abnobaviscum F®, a European mistletoe extract

Evidence suggests that mistletoe extract has the potential to be used as an anticancer agent. Abnobaviscum F® is a European mistletoe extract from the host tree Fraxinus. We investigated the effect of Abnobaviscum F on the growth and survival of different leukemia cell lines. Abnobaviscum F treatment strongly reduced survival and induced apoptosis of K562 (human myeloid leukemia), RPMI-8226 (human plasmacytoma) and L1210 (murine lymphocytic leukemia) cells in culture. Using K562 cells to further investigate the mechanism of action of Abnobaviscum F, we showed that Abnobaviscum F-induced cell death was associated with the activation of caspase-9, JNK-1/2 and p38 MAPK, as well as with the downregulation of Mcl-1, and inhibition of ERK-1/2 and PKB phosphorylation. Moreover, Abnobaviscum F treatment led to both a reduction of cellular glutathione (GSH) and the induction of ER stress (GRP78 and CHOP induction and eIF-2α phosphorylation). By contrast, Abnobaviscum F did not impact the expression of the DR4 and DR5 death receptors. The Abnobaviscum F-induced apoptosis of K562 cells was blocked by pretreatment with either GSH, z-VAD-fmk or SP600125. Our results, therefore, show that Abnobaviscum F induces apoptosis of K562 cells through the activation of the intrinsic caspase pathway, the phosphorylation of JNK-1, the reduction of cellular GSH, and the induction of ER stress.

Homoharringtonine-Induced Apoptosis of Human Leukemia HL-60 Cells is Associated with Down-Regulation of Telomerase

Homoharringtonine (HHT), first isolated from the Chinese evergreen Cephalotaxus Harringtonia, has been shown inhibiting activity in leukemia in initial studies in China and in later studies in the US, but the detailed mechanism of action is still unclear. The goal of the experiments shown here is to explore the effect of HHT on the telomerase activity and apoptosis of human leukemia HL-60 cells. The telomerase activity of HL-60 cells was examined by the telomeric repeat amplification protocol (TRAP) — an enzyme-linked immunosorbent assay (ELISA). Apoptosis was analyzed by morphological observation, DNA agarose gel electrophoresis, flow cytometry (FCM), and TdT-mediated dUTP-biotin nick end labeling (TUNEL). After treatment with HHT at 5–500 μg/l for 48 hours, the level of telomerase activity in HL-60 cells decreased in a dose-and time-dependent manner. Simultaneously, HL-60 cells underwent apoptosis. In conclusion, our data suggest that HHT can inhibit the telomerase content of HL-60 cells effectively and induce apoptosis.

Astragalus membranaceus lectin (AML) induces caspase-dependent apoptosis in human leukemia cells

OBJECTIVES

Recently, plant lectins have attracted great interest due to their various biological activities such as anti-cancer, anti-fungal and anti-viral activities. We have reported earlier concerning anti-proliferation of human cancer cell lines by a galactose-binding lectin (AML), from a Chinese herb, ASTRAGALUS MEMBRANACEUS: In the present study, detailed investigations into the mechanism of such anti-proliferation properties have been carried out.

MATERIALS AND METHODS

Mechanism of apoptosis initiation in K562 cells by AML was investigated by morphology, flow cytometry and western blot analysis.

RESULTS

AML induced apoptosis in a caspase-dependent manner in the chronic myeloid leukemia cell line, K562. Furthermore, we observed that cytotoxicity and apoptosis of K562 cells induced by AML were completely abolished in presence of lactose or galactose.

CONCLUSIONS

Our results suggest that AML could act as a potential anti-cancer drug.

Analysis and prediction of cancerlectins using evolutionary and domain information

BACKGROUND

Predicting the function of a protein is one of the major challenges in the post-genomic era where a large number of protein sequences of unknown function are accumulating rapidly. Lectins are the proteins that specifically recognize and bind to carbohydrate moieties present on either proteins or lipids. Cancerlectins are those lectins that play various important roles in tumor cell differentiation and metastasis. Although the two types of proteins are linked, still there is no computational method available that can distinguish cancerlectins from the large pool of non-cancerlectins. Hence, it is imperative to develop a method that can distinguish between cancer and non-cancerlectins.

RESULTS

All the models developed in this study are based on a non-redundant dataset containing 178 cancerlectins and 226 non-cancerlectins in which no two sequences have more than 50% sequence similarity. We have applied the similarity search based technique, i.e. BLAST, and achieved a maximum accuracy of 43.25%. The amino acids compositional analysis have shown that certain residues (e.g. Leucine, Proline) were preferred in cancerlectins whereas some other (e.g. Asparatic acid, Asparagine) were preferred in non-cancerlectins. It has been found that the PROSITE domain "Crystalline beta gamma" was abundant in cancerlectins whereas domains like "SUEL-type lectin domain" were found mainly in non-cancerlectins. An SVM-based model has been developed to differentiate between the cancer and non-cancerlectins which achieved a maximum Matthew's correlation coefficient (MCC) value of 0.32 with an accuracy of 64.84%, using amino acid compositions. We have developed a model based on dipeptide compositions which achieved an MCC value of 0.30 with an accuracy of 64.84%. Thereafter, we have developed models based on split compositions (2 and 4 parts) and achieved an MCC value of 0.31, 0.32 with accuracies of 65.10% and 66.09%, respectively. An SVM model based on Position Specific Scoring Matrix (PSSM), generated by PSI-BLAST, was developed and achieved an MCC value of 0.36 with an accuracy of 68.34%. Finally, we have integrated the PROSITE domain information with PSSM and developed an SVM model that has achieved an MCC value of 0.38 with 69.09% accuracy.

CONCLUSION

BLAST has been found inefficient to distinguish between cancer and non-cancerlectins. We analyzed the protein sequences of cancer and non-cancerlectins and identified interesting patterns. We have been able to identify PROSITE domains that are preferred in cancer and non-cancerlectins and thus provided interesting insights into the two types of proteins. The method developed in this study will be useful for researchers studying cancerlectins, lectins and cancer biology. The web-server based on the above study, is available at http://www.imtech.res.in/raghava/cancer_pred/

N-acetyl-D-galactosamine-specific lectin isolated from the seeds of Carica papaya

N-Acetyl-D-galactosamine (GalNAc)-specific lectins are of great interest because they have been reported to detect tumor-associated antigens of malignant cells. We isolated a novel lectin from Carica papaya seeds, named C. papaya lectin (CPL). Purification of the lectin involved ammonium sulfate fractionation and DEAE anion exchange and repeated gel filtration chromatography. Inhibition of CPL causing hemagglutination on human erythrocytes showed that the lectin shows specificity to GalNAc and lactose. Surface plasmon resonance further revealed that the lectin possesses high specificity toward GalNAc with a dissociation constant of 5.5 × 10(-9) M. The lectin is composed of 38- and 40-kDa subunits with a molecular mass of ∼804 kDa estimated by size-exclusion high-performance liquid chromatography. Incubation of CPL with Jurkat T cells showed significant induction of IL-2 cytokine, which suggests that CPL has potent immunomodulatory effects on immune cells.

Antitumor and HIV-1 Reverse Transcriptase Inhibitory Activities of a Hemagglutinin and a Protease Inhibitor from Mini-Black Soybean

Protease inhibitors (PIs) and hemagglutinins are defense proteins produced by many organisms. From Chinese mini-black soybeans, a 17.5-kDa PI was isolated using chromatography on Q-Sepharose, SP-Sepharose, and DEAE-cellulose. A 25-kDa hemagglutinin was purified similarly, but using Superdex 75 instead of DEAE-cellulose in the final step. The PI inhibited trypsin and chymotrypsin (IC₅₀ = 7.2 and 8.8 μM). Its trypsin inhibitory activity was stable from pH 2 to pH 13 and from 0°C to 70°C. The hemagglutinin activity of the hemagglutinin was stable from pH 2 to pH 13 and from 0°C to 75°C. The results indicated that both PI and hemagglutinin were relatively thermostable and pH-stable. The trypsin inhibitory activity was inhibited by dithiothreitol, signifying the importance of the disulfide bond to the activity. The hemagglutinating activity was inhibited most potently by D (+)-raffinose and N-acetyl-D-galactosamine, suggesting that the hemagglutinin was specific for these two sugars. Both PI and hemagglutinin inhibited HIV-1 reverse transcriptase (IC₅₀ = 3.2 and 5.5 μM), proliferation of breast cancer cells (IC₅₀ = 9.7 and 3.5 μM), and hepatoma cells (IC₅₀ = 35 and 6.2 μM), with relatively high potencies.

Difficulties and perspectives of immunomodulatory therapy with mistletoe lectins and standardized mistletoe extracts in evidence-based medicine

Viscum album preparations are aqueous mistletoe plant extracts used in complementary and alternative medicine as immunomodulators in cancer therapy. However, evidence of immunological efficacy of mistletoe extracts (MEs) used in clinical trials is often lacking. Mechanisms involved in anti-tumor properties of ME and mistletoe lectins (MLs) modify both innate and adaptive immune systems, according to animal model experiments. In the background of these effects, a selective binding of ML on CD75 ganglioside receptors of interleukin 12 (IL-12)-producing macrophages or dendritic cells can play an important role. Immunological effects of ME correlate with their lectin activity, showing a bell-shaped dose-response curve of efficacy. Therefore, a correct determination of MLs for the standardization of commercial ME is essential. However, plant MLs exhibit heterogeneity, which most likely results from post-translational processing. In addition, amino acid analysis of ML has revealed numerous conservative substitutions along their amino acid sequence. Consequently, ML research needs new perspectives, and the advantages and disadvantages of purified and biologically better defined ML preparations are also discussed in this article.

Human telomerase activity regulation

Telomerase has been recognized as a relevant factor distinguishing cancer cells from normal cells. Thus, it has become a very promising target for anticancer therapy. The cell proliferative potential can be limited by replication end problem, due to telomeres shortening, which is overcome in cancer cells by telomerase activity or by alternative telomeres lengthening (ALT) mechanism. However, this multisubunit enzymatic complex can be regulated at various levels, including expression control but also other factors contributing to the enzyme phosphorylation status, assembling or complex subunits transport. Thus, we show that the telomerase expression targeting cannot be the only possibility to shorten telomeres and induce cell apoptosis. It is important especially since the transcription expression is not always correlated with the enzyme activity which might result in transcription modulation failure or a possibility for the gene therapy to be overcome. This review summarizes the current state of knowledge of numerous telomerase regulation mechanisms that take place after telomerase subunits coding genes transcription. Thus we show the possible mechanisms of telomerase activity regulation which might become attractive anticancer therapy targets.

Lectins: production and practical applications

Lectins are proteins found in a diversity of organisms. They possess the ability to agglutinate erythrocytes with known carbohydrate specificity since they have at least one non-catalytic domain that binds reversibly to specific monosaccharides or oligosaccharides. This articles aims to review the production and practical applications of lectins. Lectins are isolated from their natural sources by chromatographic procedures or produced by recombinant DNA technology. The yields of animal lectins are usually low compared with the yields of plant lectins such as legume lectins. Lectins manifest a diversity of activities including antitumor, immunomodulatory, antifungal, HIV-1 reverse transcriptase inhibitory, and anti-insect activities, which may find practical applications. A small number of lectins demonstrate antibacterial and anti-nematode activities.

A new chitin-binding lectin from rhizome of Setcreasea purpurea with antifungal, antiviral and apoptosis-inducing activities

A 48 kDa, chitin-binding lectin with antifungal, antiviral and apoptosis-inducing activities was isolated from the rhizomes of Setcreasea purpurea Boom, a member of family Commelinaceae. Setcreasea purpurea lectin (designated as SPL) is a homotetrameric protein consisting of 12031.9 Da subunits linked by non-covalent bonds as determined by SDS-PAGE, gel filtration and MS. The N-terminal 25 amino-acid sequence of SPL, NVLGRDAYCGSQNPGATCPGLCCSK was determined and homology analysis suggested that SPL belongs to the family of chitin-binding plant lectins composed of hevein domains. The lectin exhibited strong hemagglutinating activity towards rabbit erythrocytes at 0.95 μg/ml and the activity could be reversed exclusively by chitin hydrolysate (oligomers of GlcNAc). Its hemagglutinating activity was stable in pH range of 2.0-9.0 and it showed excellent thermal tolerance. SPL showed antifungal activity against Rhizoctonia solani, Sclerotinia sclerotiorum, Penicillium italicum and Helminthosporiun maydis. It also exhibited inhibitory effect on HIV-1 (IIIB) and HIV-2 (ROD), with an EC₅₀ of 13.8 ± 1.3 and 57.1 ± 15 μg/ml, respectively. Subsequently, MTT method, cell morphological analysis and LDH activity-based cytotoxicity assays demonstrated that SPL was highly cytotoxic to CNE-1 cells and induced apoptosis in a dose-dependent manner. Moreover, due to the caspase inhibitors analyses, caspase was also found to play an important role in the potential apoptotic mechanism of SPL.