Apoptosis and lysosome membrane permeabilization induction on breast cancer cells by an anticarcinogenic Bowman-Birk protease inhibitor from Vigna unguiculata seeds. Cancer Lett. 2010;293:73-81. [PMID: 20133052 DOI: 10.1016/j.canlet.2009.12.017]

Protease Inhibitors from Plants as Therapeutic Agents- A Review

Plant-based diets are a great source of protease inhibitors (PIs). Two of the most well-known families of PIs are Bowman-Birk inhibitors (BBI) and Kunitz-type inhibitors (KTI). The first group acts mainly on trypsin, chymotrypsin, and elastase; the second is on serine, cysteine, and aspartic proteases. PIs can retard or inhibit the catalytic action of enzymes; therefore, they are considered non-nutritional compounds; nevertheless, animal studies and cell line experiments showed promising results of PIs in treating human illnesses such as obesity, cardiovascular diseases, autoimmune diseases, inflammatory processes, and different types of cancer (gastric, colorectal, breast, and lung cancer). Anticarcinogenic activity's proposed mechanisms of action comprise several inhibitory effects at different molecular levels, i.e., transcription, post-transcription, translation, post-translation, and secretion of cancer cells. This work reviews the potential therapeutic applications of PIs as anticarcinogenic and anti-inflammatory agents in human diseases and the mechanisms by which they exert these effects.

The Kunitz chymotrypsin inhibitor from Erythrina velutina seeds displays activity against HeLa cells through arrest in cell cycle

Erythrina velutina is a species of arboreal leguminous that occurs spontaneously in the northeastern states of Brazil. Leguminous seeds represent an abundant source of peptidase inhibitors, which play an important role in controlling peptidases involved in essential biological processes. The aim of this study was to purify and characterize a novel Kunitz-type peptidase inhibitor from Erythrina velutina seeds and evaluate its anti-proliferative effects against cancer cell lines. The Kunitz-type chymotrypsin inhibitor was purified from Erythrina velutina seeds (EvCI) by ammonium sulphate fractionation, trypsin- and chymotrypsin-sepharose affinity chromatographies and Resource Q anion-exchange column. The purified EvCI has a molecular mass of 18 kDa with homology to a Kunitz-type inhibitor. Inhibition assays revealed that EvCI is a competitive inhibitor of chymotrypsin (with K _i of 4 × 10^-8 M), with weak inhibitory activity against human elastase and without inhibition against trypsin, elastase, bromelain or papain. In addition, the inhibitory activity of EvCI was stable over a wide range of pH and temperature. Disulfide bridges are involved in stabilization of the reactive site in EvCI, since the reduction of disulfide bridges with DTT 100 mM abolished ~ 50% of its inhibitory activity. The inhibitor exhibited selective anti-proliferative properties against HeLa cells. The incubation of EvCI with HeLa cells triggered arrest in the cell cycle, suggesting that apoptosis is the mechanism of death induced by the inhibitor. EvCI constitutes an interesting anti-carcinogenic candidate for conventional cervical cancer treatments employed currently. The EvCI cytostatic effect on Hela cells indicates a promised compound to be used as anti-carcinogenic complement for conventional cervical treatments employed currently.

Bowman-Birk Inhibitors: Insights into Family of Multifunctional Proteins and Peptides with Potential Therapeutical Applications

Bowman-Birk inhibitors (BBIs) are found primarily in seeds of legumes and in cereal grains. These canonical inhibitors share a highly conserved nine-amino acids binding loop motif CTP1SXPPXC (where P1 is the inhibitory active site, while X stands for various amino acids). They are natural controllers of plants' endogenous proteases, but they are also inhibitors of exogenous proteases present in microbials and insects. They are considered as plants' protective agents, as their elevated levels are observed during injury, presence of pathogens, or abiotic stress, i.a. Similar properties are observed for peptides isolated from amphibians' skin containing 11-amino acids disulfide-bridged loop CWTP1SXPPXPC. They are classified as Bowman-Birk like trypsin inhibitors (BBLTIs). These inhibitors are resistant to proteolysis and not toxic, and they are reported to be beneficial in the treatment of various pathological states. In this review, we summarize up-to-date research results regarding BBIs' and BBLTIs' inhibitory activity, immunomodulatory and anti-inflammatory activity, antimicrobial and insecticidal strength, as well as chemopreventive properties.

Identification and Target-Modification of SL-BBI: A Novel Bowman-Birk Type Trypsin Inhibitor from Sylvirana latouchii

The peptides from the ranacyclin family share similar active disulphide loop with plant-derived Bowman-Birk type inhibitors, some of which have the dual activities of trypsin inhibition and antimicrobial. Herein, a novel Bowman-Birk type trypsin inhibitor of the ranacyclin family was identified from the skin secretion of broad-folded frog (Sylvirana latouchii) by molecular cloning method and named as SL-BBI. After chemical synthesis, it was proved to be a potent inhibitor of trypsin with a Ki value of 230.5 nM and showed weak antimicrobial activity against tested microorganisms. Modified analogue K-SL maintains the original inhibitory activity with a Ki value of 77.27 nM while enhancing the antimicrobial activity. After the substitution of active P1 site to phenylalanine and P2' site to isoleucine, F-SL regenerated its inhibitory activity on chymotrypsin with a Ki value of 309.3 nM and exhibited antiproliferative effects on PC-3, MCF-7 and a series of non-small cell lung cancer cell lines without cell membrane damage. The affinity of F-SL for the β subunits in the yeast 20S proteasome showed by molecular docking simulations enriched the understanding of the possible action mode of Bowman-Birk type inhibitors. Further mechanistic studies have shown that F-SL can activate caspase 3/7 in H157 cells and induce apoptosis, which means it has the potential to become an anticancer agent.

Blood pressure-lowering effects of a Bowman-Birk inhibitor and its derived peptides in normotensive and hypertensive rats

Bioactive plant peptides have received considerable interest as potential antihypertensive agents with potentially fewer side effects than antihypertensive drugs. Here, the blood pressure-lowering effects of the Bowman-Birk protease inhibitor, BTCI, and its derived peptides, PepChy and PepTry, were investigated using normotensive (Wistar-WR) and spontaneously hypertensive rats (SHR). BTCI inhibited the proteases trypsin and chymotrypsin, respectively, at 6 µM and 40 µM, a 10-fold greater inhibition than observed with PepTry (60 µM) and PepChy (400 µM). These molecules also inhibited angiotensin converting enzyme (ACE) with IC50 values of 54.6 ± 2.9; 24.7 ± 1.1; and 24.4 ± 1.1 µM, respectively, occluding its catalytic site, as indicated by molecular docking simulation, mainly for PepChy and PepTry. Gavage administration of BTCI and the peptides promoted a decrease of systolic and diastolic blood pressure and an increase of renal and aortic vascular conductance. These effects were more expressive in SHR than in WR. Additionally, BTCI, PepChy and PepTry promoted coronary vasodilation and negative inotropic effects in isolated perfused hearts. The nitric oxide synthase inhibitor blunted the BTCI and PepChy, with no cardiac effects on PepTry. The findings of this study indicate a therapeutic potential of BTCI and its related peptides in the treatment of hypertension.

Neutrophil elastase inhibitor purification strategy from cowpea seeds

Serine proteases and its inhibitors are involved in physiological process and its deregulation lead to various diseases like Chronic Obstructive Pulmonary Disease (COPD), pulmonary emphysema, skin diseases, atherosclerosis, coagulation diseases, cancer, inflammatory diseases, neuronal disorders and other diseases. Serine protease inhibitors have been described in many species, as well as in plants, including cowpea beans (Vigna unguiculata (L.) Walp). Here, we purified and characterized a protease inhibitor, named VuEI (Vigna unguiculata elastase inhibitor), from Vigna unguiculata, with inhibitory activity against HNE (human neutrophil elastase) and chymotrypsin but has no inhibitory activity against trypsin and thrombin. VuEI was obtained by alkaline protein extraction followed by three different chromatographic steps in sequence. First, an ion exchange chromatography using Hitrap Q column was employed, followed by two reversed-phase chromatography using Source15RPC and ACE18 columns. The molecular mass of VuEI was estimated in 10.99 kDa by MALDI-TOF mass spectrometry. The dissociation constant (Ki) to HNE was 9 pM. These data indicate that VuEI is a potent inhibitor of human neutrophil elastase, besides to inhibit chymotrypsin.

Chemical Constituents of Vigna luteola and Their Anti-inflammatory Bioactivity

Seventy-three compounds were identified from the methanol extract of V. luteola, and among these, three new (1–3) were characterized by spectroscopic and mass spectrometric analyses. The isolated constituents were assessed for anti-inflammatory potential evaluation, and several purified principles exhibited significant superoxide anion and elastase inhibitory effects.

Crystallographic structure of a complex between trypsin and a nonapeptide derived from a Bowman-Birk inhibitor found in Vigna unguiculata seeds

Natural inhibitors of proteases have been classified into different families, among them is the Bowman-Birk Inhibitor (BBI) family. Members of BBI have two structurally reactive loops that simultaneously inhibit trypsin and chymotrypsin. Here, we have investigated the binding of bovine trypsin by a cyclic nonapeptide, named PTRY9 (CTKSIPPQC), derived of the black-eyed pea trypsin/chymotrypsin inhibitor (BTCI) from Vigna unguiculata seeds. This peptide was synthetically produced with the disulfide bond restraining its conformation to mimic the reactive loop that inhibits trypsin. PTRY9 complexed to pancreatic bovine trypsin was crystallized in orthorhombic and trigonal space groups, P2₁2₁2₁ and P3₂21, with maximum resolutions of 1.15 and 1.61 Å, respectively. The structures presented refinement parameters of R_work = 14.52 % and R_free = 15.59 %; R_work = 15.60 % and R_free = 18.78 %, and different surface area between the peptide and the enzyme of 1024 Ų and 1070 Ų, respectively. The binding site of the PTRY9 is similar to that found for BTCI as shown by a r.m.s.d. of 0.358 Å between the superimposed structures and the electrostatic complementary pattern at the enzyme-peptide interface. Additionally, enzyme inhibition assays show that the affinity of trypsin for PTRY9 is smaller than that for BTCI. In vitro assays revealed that, like BTCI, this synthetic peptide is not cytotoxic for normal mammary epithelial MCF-10A cells, but exerts cytotoxic effects on MDA.MB.231 invasive human breast cancer cells.

Cowpea: an overview on its nutritional facts and health benefits

Cowpea (Vigna unguiculata) is a legume consumed as a high-quality plant protein source in many parts of the world. High protein and carbohydrate contents with a relatively low fat content and a complementary amino acid pattern to that of cereal grains make cowpea an important nutritional food in the human diet. Cowpea has gained more attention recently from consumers and researchers worldwide as a result of its exerted health beneficial properties, including anti-diabetic, anti-cancer, anti-hyperlipidemic, anti-inflammatory and anti-hypertensive properties. Among the mechanisms that have been proposed in the prevention of chronic diseases, the most proven are attributed to the presence of compounds such as soluble and insoluble dietary fiber, phytochemicals, and proteins and peptides in cowpea. However, studies on the anti-cancer and anti-inflammatory properties of cowpea have produced conflicting results. Some studies support a protective effect of cowpea on the progression of cancer and inflammation, whereas others did not reveal any. Because there are only a few studies addressing health-related effects of cowpea consumption, further studies in this area are suggested. In addition, despite the reported favorable effects of cowpea on diabetes, hyperlipidemia and hypertension, a long-term epidemiological study investigating the association between cowpea consumption and diabetes, cardiovascular disease and cancer is also recommended. © 2018 Society of Chemical Industry.

Optimizing liposomes for delivery of Bowman-Birk protease inhibitors - Platforms for multiple biomedical applications

One of the major challenges in the administration of therapeutic proteins involves delivery limitations. Liposomes are well-known drug delivery systems (DDS) that have been used to overcome this drawback; nevertheless, low protein entrapment efficiency (EE) still limits their wide biomedical application on a commercial scale. In the present work, different methods for protein entrapment into liposomes were tested in order to obtain tailored DDS platforms for multiple biomedical applications. The protein used as model was the Black-eyed pea Trypsin and Chymotrypsin Inhibitor (BTCI), a member of the Bowman-Birk protease inhibitor family (BBIs), which has been largely explored for its potential application in many biomedical therapies. We optimized reverse-phase evaporation (REV) and freeze/thaw (F/T) entrapment methods, using a cationic lipid matrix to entrap expressive amounts of BTCI (∼100 μM) in stable liposomes without affecting its protease inhibition activity. The influence of various parameters (e.g. entrapment method, liposome composition, buffer type) on particle size, charge, polydispersity, and EE of liposomes was investigated to provide an insight on how to control such parameters in view of obtaining a high entrapment yield. In addition, BTCI liposome platforms obtained herein showed to be versatile vesicles, allowing surface modification with moieties/polymers of interest (e.g. PEG, transferrin). The aforementioned results are relevant to focusing on the entrapment of other promising BBIs or protein agents sharing similar structural features. These findings encourage future studies to investigate the advantages of using the liposome platforms presented herein to broaden the use of this type of DDS for BBI biomedical applications.

A Bowman-Birk type chymotrypsin inhibitor peptide from the amphibian, Hylarana erythraea

The first amphibian skin secretion-derived Bowman-Birk type chymotrypsin inhibitor is described here from the Asian green frog, Hylarana erythraea, and was identified by use of molecular cloning and tandem mass spectrometric amino acid sequencing. It was named Hylarana erythraea chymotrypsin inhibitor (HECI) and in addition to inhibition of chymotrypsin (Ki = 3.92 ± 0.35 μM), the peptide also inhibited the 20 S proteasome (Ki = 8.55 ± 1.84  μM). Additionally, an analogue of HECI, named K⁹-HECI, in which Phe⁹ was substituted by Lys⁹ at the P1 position, was functional as a trypsin inhibitor. Both peptides exhibited anti-proliferation activity against the human cancer cell lines, H157, PC-3 and MCF-7, up to a concentration of 1 mM and possessed a low degree of cytotoxicity on normal cells, HMEC-1. However, HECI exhibited higher anti-proliferative potency against H157. The results indicate that HECI, inhibiting chymotryptic-like activity of proteasome, could provide new insights in treatment of lung cancer.

Lycopene-rich extract from red guava (Psidium guajava L.) displays cytotoxic effect against human breast adenocarcinoma cell line MCF-7 via an apoptotic-like pathway

This study investigated a lycopene-rich extract from red guava (LEG) for its chemical composition using spectrophotometry, mass spectrometry, attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), and computational studies. The cytotoxic activity of LEG and the underlying mechanism was studied in human breast adenocarcinoma cells (MCF-7), murine fibroblast cells (NIH-3T3), BALB/c murine peritoneal macrophages, and sheep blood erythrocytes by evaluating the cell viability with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method and flow cytometry. Spectrophotometry analysis showed that LEG contained 20% of lycopene per extract dry weight. Experimental and theoretical ATR-FTIR suggests the presence of lycopene, whereas MS/MS spectra obtained after fragmentation of the molecular ion [M]+• of 536.4364 show fragment ions at m/z 269.2259, 375.3034, 444.3788, and 467.3658, corroborating the presence of lycopene mostly related to all-trans configuration. Treatment with LEG (1600 to 6.25μg/mL) for 24 and 72h significantly affected the viability of MCF-7 cells (mean half maximal inhibitory concentration [IC50]=29.85 and 5.964μg/mL, respectively) but not NIH-3T3 cells (IC50=1579 and 911.5μg/mL, respectively). Furthermore LEG at concentrations from 800 to 6.25μg/mL presented low cytotoxicity against BALB/c peritoneal macrophages (IC50≥800μg/mL) and no hemolytic activity. LEG (400 and 800μg/mL) caused reduction in the cell proliferation and induced cell cycle arrest, DNA fragmentation, modifications in the mitochondrial membrane potential, and morphologic changes related to granularity and size in MCF-7 cells; however, it failed to cause any significant damage to the cell membrane or display necrosis or traditional apoptosis. In conclusion, LEG was able to induce cytostatic and cytotoxic effects on breast cancer cells probably via induction of an apoptotic-like pathway.

Plant Protease Inhibitors in Therapeutics-Focus on Cancer Therapy

Plants are known to have many secondary metabolites and phytochemical compounds which are highly explored at biochemical and molecular genetics level and exploited enormously in the human health care sector. However, there are other less explored small molecular weight proteins, which inhibit proteases/proteinases. Plants are good sources of protease inhibitors (PIs) which protect them against diseases, insects, pests, and herbivores. In the past, proteinaceous PIs were considered primarily as protein-degrading enzymes. Nevertheless, this view has significantly changed and PIs are now treated as very important signaling molecules in many biological activities such as inflammation, apoptosis, blood clotting and hormone processing. In recent years, PIs have been examined extensively as therapeutic agents, primarily to deal with various human cancers. Interestingly, many plant-based PIs are also found to be effective against cardiovascular diseases, osteoporosis, inflammatory diseases and neurological disorders. Several plant PIs are under further evaluation in in vitro clinical trials. Among all types of PIs, Bowman-Birk inhibitors (BBI) have been studied extensively in the treatment of many diseases, especially in the field of cancer prevention. So far, crops such as beans, potatoes, barley, squash, millet, wheat, buckwheat, groundnut, chickpea, pigeonpea, corn, and pineapple have been identified as good sources of PIs. The PI content of such foods has a significant influence on human health disorders, particularly in the regions where people mostly depend on these kind of foods. These natural PIs vary in concentration, protease specificity, heat stability, and sometimes several PIs may be present in the same species or tissue. However, it is important to carry out individual studies to identify the potential effects of each PI on human health. PIs in plants make them incredible sources to determine novel PIs with specific pharmacological and therapeutic effects due to their peculiarity and superabundance.

Selective depletion of tumour suppressors Deleted in Colorectal Cancer (DCC) and neogenin by environmental and endogenous serine proteases: linking diet and cancer

BACKGROUND

The related tumour suppressor proteins Deleted in Colorectal Cancer (DCC) and neogenin are absent or weakly expressed in many cancers, whereas their insertion into cells suppresses oncogenic behaviour. Serine proteases influence the initiation and progression of cancers although the mechanisms are unknown.

METHODS

The effects of environmental (bacterial subtilisin) and endogenous mammalian (chymotrypsin) serine proteases were examined on protein expression in fresh, normal tissue and human neuroblastoma and mammary adenocarcinoma lines. Cell proliferation and migration assays (chemoattraction and wound closure) were used to examine cell function. Cells lacking DCC were transfected with an ectopic dcc plasmid.

RESULTS

Subtilisin and chymotrypsin selectively depleted DCC and neogenin from cells at nanomolar concentrations without affecting related proteins. Cells showed reduced adherence and increased migration, but after washing they re-attached within 24 h, with recovery of protein expression. These effects are induced by chymotryptic activity as they are prevented by chymostatin and the soybean Bowman-Birk inhibitor typical of many plant protease inhibitors.

CONCLUSIONS

Bacillus subtilis, which secretes subtilisin is widely present in soil, the environment and the intestinal contents, while subtilisin itself is used in meat processing, animal feed probiotics and many household cleaning agents. With chymotrypsin present in chyme, blood and tissues, these proteases may contribute to cancer development by depleting DCC and neogenin. Blocking their activity by Bowman-Birk inhibitors may explain the protective effects of a plant diet. Our findings identify a potential non-genetic contribution to cancer cell behaviour which may explain both the association of processed meats and other factors with cancer incidence and the protection afforded by plant-rich diets, with significant implications for cancer prevention.

A Bowman-Birk inhibitor induces apoptosis in human breast adenocarcinoma through mitochondrial impairment and oxidative damage following proteasome 20S inhibition

Proteasome inhibitors are emerging as a new class of chemopreventive agents and have gained huge importance as potential pharmacological tools in breast cancer treatment. Improved understanding of the role played by proteases and their specific inhibitors in humans offers novel and challenging opportunities for preventive and therapeutic intervention. In this study, we demonstrated that the Bowman-Birk protease inhibitor from Vigna unguiculata seeds, named black-eyed pea trypsin/chymotrypsin Inhibitor (BTCI), potently suppresses human breast adenocarcinoma cell viability by inhibiting the activity of proteasome 20S. BTCI induced a negative growth effect against a panel of breast cancer cells, with a concomitant cytostatic effect at the G2/M phase of the cell cycle and an increase in apoptosis, as observed by an augmented number of cells at the sub-G1 phase and annexin V-fluorescin isothiocyanate (FITC)/propidium iodide (PI) staining. In contrast, BTCI exhibited no cytotoxic effect on normal mammary epithelial cells. Moreover, the increased levels of intracellular reactive oxygen species (ROS) and changes in the mitochondrial membrane potential in cells treated with BTCI indicated mitochondrial damage as a crucial cellular event responsible for the apoptotic process. The higher activity of caspase in tumoral cells treated with BTCI in comparison with untreated cells suggests that BTCI induces apoptosis in a caspase-dependent manner. BTCI affected NF-kB target gene expression in both non invasive and invasive breast cancer cell lines, with the effect highly pronounced in the invasive cells. An increased expression of interleukin-8 (IL-8) in both cell lines was also observed. Taken together, these results suggest that BTCI promotes apoptosis through ROS-induced mitochondrial damage following proteasome inhibition. These findings highlight the pharmacological potential and benefit of BTCI in breast cancer treatment.

Bowman-Birk protease inhibitor from Vigna unguiculata seeds enhances the action of bradykinin-related peptides

The hydrolysis of bradykinin (Bk) by different classes of proteases in plasma and tissues leads to a decrease in its half-life. Here, Bk actions on smooth muscle and in vivo cardiovascular assays in association with a protease inhibitor, Black eyed-pea trypsin and chymotrypsin inhibitor (BTCI) and also under the effect of trypsin and chymotrypsin were evaluated. Two synthetic Bk-related peptides, Bk₁ and Bk₂, were used to investigate the importance of additional C-terminal amino acid residues on serine protease activity. BTCI forms complexes with Bk and analogues at pH 5.0, 7.4 and 9.0, presenting binding constants ranging from 10³ to 10⁴ M⁻¹. Formation of BTCI-Bk complexes is probably driven by hydrophobic forces, coupled with slight conformational changes in BTCI. In vitro assays using guinea pig (Cavia porcellus) ileum showed that Bk retains the ability to induce smooth muscle contraction in the presence of BTCI. Moreover, no alteration in the inhibitory activity of BTCI in complex with Bk and analogous was observed. When the BTCI and BTCI-Bk complexes were tested in vivo, a decrease of vascular resistance and consequent hypotension and potentiating renal and aortic vasodilatation induced by Bk and Bk₂ infusions was observed. These results indicate that BTCI-Bk complexes may be a reliable strategy to act as a carrier and protective approach for Bk-related peptides against plasma serine proteases cleavage, leading to an increase in their half-life. These findings also indicate that BTCI could remain stable in some tissues to inhibit chymotrypsin or trypsin-like enzymes that cleave and inactivate bradykinin in situ.

PVM/MA-shelled selol nanocapsules promote cell cycle arrest in A549 lung adenocarcinoma cells

BACKGROUND

Selol is an oily mixture of selenitetriacylglycerides that was obtained as a semi-synthetic compound containing selenite. Selol is effective against cancerous cells and less toxic to normal cells compared with inorganic forms of selenite. However, Selol's hydrophobicity hinders its administration in vivo. Therefore, the present study aimed to produce a formulation of Selol nanocapsules (SPN) and to test its effectiveness against pulmonary adenocarcinoma cells (A549).

RESULTS

Nanocapsules were produced through an interfacial nanoprecipitation method. The polymer shell was composed of poly(methyl vinyl ether-co-maleic anhydride) (PVM/MA) copolymer. The obtained nanocapsules were monodisperse and stable. Both free Selol (S) and SPN reduced the viability of A549 cells, whereas S induced a greater reduction in non-tumor cell viability than SPN. The suppressor effect of SPN was primarily associated to the G2/M arrest of the cell cycle, as was corroborated by the down-regulations of the CCNB1 and CDC25C genes. Apoptosis and necrosis were induced by Selol in a discrete percentage of A549 cells. SPN also increased the production of reactive oxygen species, leading to oxidative cellular damage and to the overexpression of the GPX1, CYP1A1, BAX and BCL2 genes.

CONCLUSIONS

This study presents a stable formulation of PVM/MA-shelled Selol nanocapsules and provides the first demonstration that Selol promotes G2/M arrest in cancerous cells.

Effects of an anticarcinogenic Bowman-Birk protease inhibitor on purified 20S proteasome and MCF-7 breast cancer cells

Proteasome inhibitors have been described as an important target for cancer therapy due to their potential to regulate the ubiquitin-proteasome system in the degradation pathway of cellular proteins. Here, we reported the effects of a Bowman-Birk-type protease inhibitor, the Black-eyed pea Trypsin/Chymotrypsin Inhibitor (BTCI), on proteasome 20S in MCF-7 breast cancer cells and on catalytic activity of the purified 20S proteasome from horse erythrocytes, as well as the structural analysis of the BTCI-20S proteasome complex. In vitro experiments and confocal microscopy showed that BTCI readily crosses the membrane of the breast cancer cells and co-localizes with the proteasome in cytoplasm and mainly in nucleus. Indeed, as indicated by dynamic light scattering, BTCI and 20S proteasome form a stable complex at temperatures up to 55°C and at neutral and alkaline pHs. In complexed form, BTCI strongly inhibits the proteolytic chymotrypsin-, trypsin- and caspase-like activities of 20S proteasome, indicated by inhibition constants of 10⁻⁷ M magnitude order. Besides other mechanisms, this feature can be associated with previously reported cytostatic and cytotoxic effects of BTCI in MCF-7 breast cancer cells by means of apoptosis.

Anticancer effects of sweet potato protein on human colorectal cancer cells

AIM: To investigate the effects of proteins purified from sweet potato storage roots on human colorectal cancer cell lines.

METHODS: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, Hoechst 33258 nuclear staining and Boyden transwell chamber methods were used to determine whether purified sweet potato protein (SPP) from fresh sweet potato roots affected proliferation, migration and invasion, respectively, of human colorectal cancer SW480 cells in vitro. The inhibitory effects of SPP on growth of human colorectal cancer HCT-8 cells intraperitoneally xenografted in nude mice and spontaneous lung metastasis of murine Lewis lung carcinoma 3LL cells subcutaneously transplanted in C57 BL/6 mice were also investigated in vivo.

RESULTS: SPP inhibited the proliferation of SW480 cells in a dose-dependent manner, with an IC₅₀ value of 38.732 μmol/L (r² = 0.980, P = 0.003) in the MTT assay. Hoechst 33258 nuclear staining further revealed inhibition of cell viability and induction of apoptosis by SPP. The transwell assay disclosed significant reduction in migrated cells/field by 8 μmol/L SPP (8.4 ± 2.6 vs 23.3 ± 5.4, P = 0.031) and invaded cells/field through the ECMatrix by 0.8 μmol/L SPP, compared with the control (25.2 ± 5.2 vs 34.8 ± 6.1, P = 0.038). Both intraperitoneal (ip) and intragastric (ig) administration of SPP led to significant suppression of growth of intraperitoneally inoculated HCT-8 cells in nude mice to 58.0% ± 5.9% (P = 0.037) and 43.5% ± 7.1% (P = 0.004) of the controls, respectively, after 9 d treatment. Bloody ascites additionally disappeared after ip injection of trypsin inhibitor. Notably, ig and ip administration of SPP induced a significant decrease in spontaneous pulmonary metastatic nodule formation in C57 BL/6 mice (21.0 ± 12.3 and 27.3 ± 12.7 nodules/lung vs 42.5 ± 4.5 nodules/lung in controls, respectively, P < 0.05) after 25 d treatment. Moreover, the average weight of primary tumor nodules in the hind leg of mice decreased from 8.2 ± 1.3 g/mice in the control to 6.1 ± 1.4 g/mice in the ip group (P = 0.035).

CONCLUSION: SPP exerts significant antiproliferative and antimetastatic effects on human colorectal cancer cell lines, both in vitro and in vivo.

Modulatory effect of Ganoderma lucidum on expression of xenobiotic enzymes, oxidant-antioxidant and hormonal status in 7,12-dimethylbenz(a)anthracene-induced mammary carcinoma in rats

BACKGROUND

Mushrooms are an important natural source represents a major and untapped potent pharmaceutical product. Ganoderma lucidum (G. lucidum) an important medicinal mushroom has been shown to contain high amount of antioxidant. However, in vivo studies on G. lucidum fruiting bodies are lacking.

OBJECTIVES

To determine the effects of G. lucidum fruiting bodies ethanolic extract (GLEet) on expression of xenobiotic enzymes, oxidant-antioxidant and hormonal status on 7,12-dimethyl benz[a]antheracene (DMBA) induced experimental breast cancer was investigated in female Sprague dawley rats.

MATERIALS AND METHODS

Cancer bearing female Sprague dawley rats was orally treated with GLEet (500mg/kg body weight) for 16 weeks. Incidence and tumor volume in each groups, and biochemical parameters were carried out in plasma, liver, and mammary tissues of animals. Histopathological and immunohistochemical analysis were also determined.

RESULT

Oral administration of GLEet on tumor bearing animals significantly diminished the levels of lipid peroxidation thereby enhancing the nonenzymatic antioxidants and also positively regulated the estrogen receptor hormones level to near normal when compared with DMBA treated rats. Moreover, it also positively modulates the xenobiotic metabolizing enzymes. Therefore, the dietary administration of G. lucidum may be efficiently used as a chemopreventive agent against mammary carcinogenesis.

CONCLUSION

We concluded that G. lucidum is a potent chemopreventive agent, thereby it offers maximum protection against DMBA-induced mammary carcinogenesis.

Apoptosis Effect of Girinimbine Isolated from Murraya koenigii on Lung Cancer Cells In Vitro

Murraya koenigii Spreng has been traditionally claimed as a remedy for cancer. The current study investigated the anticancer effects of girinimbine, a carbazole alkaloid isolated from Murraya koenigii Spreng, on A549 lung cancer cells in relation to apoptotic mechanistic pathway. Girinimbine was isolated from Murraya koenigii Spreng. The antiproliferative activity was assayed using MTT and the apoptosis detection was done by annexin V and lysosomal stability assays. Multiparameter cytotoxicity assays were performed to investigate the change in mitochondrial membrane potential and cytochrome c translocation. ROS, caspase, and human apoptosis proteome profiler assays were done to investigate the apoptotic mechanism of cell death. The MTT assay revealed that the girinimbine induces cell death with an IC₅₀ of 19.01 μM. A significant induction of early phase of apoptosis was shown by annexin V and lysosomal stability assays. After 24 h treatment with 19.01 μM of girinimbine, decrease in the nuclear area and increase in mitochondrial membrane potential and plasma membrane permeability were readily visible. Moreover the translocation of cytochrome c also was observed. Girinimbine mediates its antiproliferative and apoptotic effects through up- and downregulation of apoptotic and antiapoptotic proteins. There was a significant involvement of both intrinsic and extrinsic pathways. Moreover, the upregulation of p53 as well as the cell proliferation repressor proteins, p27 and p21, and the significant role of insulin/IGF-1 signaling were also identified. Moreover the caspases 3 and 8 were found to be significantly activated. Our results taken together indicated that girinimbine may be a potential agent for anticancer drug development.

Role of serine proteases in inflammation: Bowman-Birk protease inhibitor (BBI) as a potential therapy for autoimmune diseases

Serine proteases, a sub-category of the protease family, participate in various physiologic and pathologic conditions. Serine proteases are involved in different arms of the immune system and play an important role in inflammation. They have been evaluated as therapeutic targets in several inflammatory diseases. The Bowman-Birk protease inhibitor (BBI), a soybean-derived serine protease inhibitor, is resistant to temperature and acidic conditions. These characteristics make it a good candidate for oral administration, with no major side effects. In addition, the therapeutic effect of BBI has been shown in inflammatory diseases and cancer. We have demonstrated the immunoregulatory and anti-inflammatory effects of BBI in the experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis. Here we review the role of serine proteases in inflammatory diseases, with emphasis on the potential of BBI as a novel oral therapy for multiple sclerosis.

Constituents from Vigna vexillata and their anti-inflammatory activity

The seeds of Vigna genus are important food resources and there have already been many reports regarding their bioactivities. In our preliminary bioassay, the chloroform layer of methanol extracts of V. vexillata demonstrated significant anti-inflammatory bioactivity. Therefore, the present research is aimed to purify and identify the anti-inflammatory principles of V. vexillata. One new sterol (1) and two new isoflavones (2,3) were reported from the natural sources for the first time and their chemical structures were determined by the spectroscopic and mass spectrometric analyses. In addition, 37 known compounds were identified by comparison of their physical and spectroscopic data with those reported in the literature. Among the isolates, daidzein (23), abscisic acid (25), and quercetin (40) displayed the most significant inhibition of superoxide anion generation and elastase release.

Morphological characteristics and co-stimulatory molecule (CD80, CD86, CD40) expression in tumor infiltrating dendritic cells in human endometrioid adenocarcinoma

OBJECTIVE

The purpose of this study was to investigate changes of the antigen-presenting function of tumor infiltrating dendritic cells (TIDCs) in human endometrioid adenocarcinoma.

STUDY DESIGN

The TIDCs from 45 cases of endometrioid adenocarcinoma were compared with 20 cases of normal human endometrial tissue, using transmission electron microscopic examination, and the expression of CD80, CD86, and CD40 was analyzed by flow cytometry.

RESULTS

In comparison with the control group, the ultrastructure of TIDCs in human endometrioid adenocarcinoma showed the following differences: numerous TIDCs were small in volume and round in shape but some were oval and multi-angular. The cytoplasmic processes were obviously decreased in number and stubbed. Round primary lysosomes with high electron-dense granules, and secondary lysosomes with high or low electron-dense granules were seen frequently in the cytoplasm. TIDCs contained much rough endoplasmic reticulum (RER). Vacuoles with flocculent electron-dense granules were rare. High electron-dense contents in the granules were near one side and the other side was bright. The nucleus became markedly small in volume, nephroid or hoofed in shape. The nucleus had little euchromatin and lots of heterochromatin under the nuclear membrane. The levels of expression of CD80, CD86 and CD40 on TIDCs were low or even nonexistent. The expression levels of CD80, CD86 and CD40 on DCs in human normal endometrium were significantly higher than those on TIDCs in endometrioid adenocarcinoma.

CONCLUSION

It is suggested that morphological differences and low expression of co-stimulatory molecules on TIDCs in endometrioid adenocarcinoma reflected the functional changes of the TIDCs in uptake, processing and presenting antigen, which may lead to the occurrence of tumor immune escape.

A review of pharmacological and toxicological potentials of marine cyanobacterial metabolites

Novel toxic metabolites from marine cyanobacteria have been thoroughly explored. Biologically active and chemically diverse compounds that could be hepatotoxic, neurotoxic or cytotoxic, such as cyclic peptides, lipopeptides, fatty acid amides, alkaloids and saccharides, have been produced from marine cyanobacteria. Many reports have revealed that biosynthesis of active metabolites is predominant during cyanobacterial bloom formation. Marine cyanobacterial toxic metabolites exhibit important biological properties, such as interfering in signal transduction either by activation or blockage of sodium channels or by targeting signaling proteins; inducing apoptosis by disrupting cytoskeletal proteins; and inhibiting membrane transporters, receptors, serine proteases and topoisomerases. The pharmacological importance of these metabolites resides in their proliferation and growth-controlling abilities towards cancer cell lines and disease-causing potent microbial agents (bacteria, virus, fungi and protozoa). Besides their toxic and pharmacological potentials, the present review discusses structural and functional resemblance of marine cyanobacterial metabolites to marine algae, sponges and mollusks.

The role of nutraceutical proteins and peptides in apoptosis, angiogenesis, and metastasis of cancer cells

The process of carcinogenesis is complex and not easy to eliminate. It includes the initial occurrence of genetic alterations which can lead to the inactivation of tumor-suppressor genes and further accumulation of genetic alterations during tumor progression. Looking for food and food components with biological properties, collectively called nutraceuticals, that can hinder such alterations and prevent the inactivation of tumor-suppressor genes is a very promising area for cancer prevention. Proteins and peptides are one group of nutraceuticals that show potential results in preventing the different stages of cancer including initiation, promotion, and progression. In this review, we summarized current knowledge on the use of nutraceutical proteins and peptides in cancer prevention and treatment. We focused on the role of plant protease inhibitors, lactoferrin and lactoferricin, shark cartilage, plant lectins, and lunasin in the apoptosis, angiogenesis, and metastasis of cancer cells. Also included are studies on bioavailability and clinical trials conducted on these promising proteins and peptides.