The impaired viability of prostate cancer cell lines by the recombinant plant kallikrein inhibitor

Impairment of SK-MEL-28 Development-A Human Melanoma Cell Line-By the Crataeva tapia Bark Lectin and Its Sequence-Derived Peptides

Melanoma is difficult to treat with chemotherapy, prompting the need for new treatments. Protease inhibitors have emerged as promising candidates as tumor cell proteases promote metastasis. Researchers have developed a chimeric form of the Bauhinia bauhinioides kallikrein inhibitor, rBbKIm, which has shown negative effects on prostate tumor cell lines DU145 and PC3. Crataeva tapia bark lectin, CrataBL, targets sulfated oligosaccharides in glycosylated proteins and has also demonstrated deleterious effects on prostate and glioblastoma tumor cells. However, neither rBbKIm nor its derived peptides affected the viability of SK-MEL-28, a melanoma cell line, while CrataBL decreased viability by over 60%. Two peptides, Pep. 26 (Ac-Q-N-S-S-L-K-V-V-P-L-NH2) and Pep. 27 (Ac-L-P-V-V-K-L-S-S-N-Q-NH2), were also tested. Pep. 27 suppressed cell migration and induced apoptosis when combined with vemurafenib, while Pep. 26 inhibited cell migration and reduced nitric oxide and the number of viable cells. Vemurafenib, a chemotherapy drug used to treat melanoma, was found to decrease the release of interleukin 8 and PDGF-AB/BB cytokines and potentiated the effects of proteins and peptides in reducing these cytokines. These findings suggest that protease inhibitors may be effective in blocking melanoma cells and highlight the potential of CrataBL and its derived peptides.

Structural and functional properties of rBmTI-A: A Kunitz-BPTI serine protease inhibitor with therapeutical potential

Serine proteases are an important group of enzymes present in several organisms such as viruses, bacteria and eukaryotes involved in several physiological and pathological processes such as cancer, neurodegeneration, tissue inflammation and infections. Kunitz-type serine protease inhibitors have been studied as therapeutical targets with positive results in many of these diseases. rBmTI-A (recombinant B. microplus Trypsin Inhibitor A) is a Kunitz-BPTI type inhibitor based on the native protein BmTI-A. BmTI-A was extracted from tick larvae and presented inhibitory activity against trypsin, human plasma kallikrein (HuPK), human neutrophil elastase (HNE) and human plasmin. rBmTI-A presented the same inhibitory activities of the BmTI-A and its thermostability has already been demonstrated. In emphysema induced by porcine pancreatic elastase (PPE) and by cigarette smoke animal models, the treatment using rBmTI-A showed a protective effect against the development of pulmonary emphysema and prevented the increase of inflammatory cells. In chronic allergic animal model, rBmTI-A treatment resulted in attenuated bronchial hyperresponsiveness, inflammation, remodeling. These are important physiological results in emphysema and lung inflammatory animal models with rBmTI-A treatment confirming its therapeutical potential.

In-vitro anti-inflammatory activity of serine protease inhibitor from Cassia siamea and Dolichos biflorus: A comparative study

Cassia siamea is a nonedible legume belonging to Fabaceae. The seed of C. siamea contains ~16% of protein. The study reports the biochemical characterization of purified novel serine protease inhibitor from seeds of C. siamea, aimed with assessing the anti-inflammatory activity. The seed extract was subjected to ammonium sulfate precipitation followed by fast protein liquid chromatography (FPLC)-anion exchange chromatography and affinity-chromatography to obtain a relative pure protease inhibitor. Thirty-fivefold purification with the specific activity of 250 U/mg of trypsin inhibitory unit was obtained. The characterization of protease inhibitor for optimum temperature, pH, and metal ions were measured using N-α-benzoyl-DL-arginine-p-nitroanilide (BAPNA) assay and casein zymogram. The C. siamea trypsin inhibitor (CsTI) has a relative molecular mass of 25.540 kDa. Purified CsTI and Dolichos biflorus were tested for anti-inflammatory efficacy against A549 and RAW264.7 cell lines. The inhibitory activity of both purified inhibitors are comparable and are potent toward anti-inflammatory activity. The purified inhibitor shows to be a promising candidate as anti-inflammatory agent by targeting the serine proteases.

"Cow's Hoof" (Bauhinia L., Leguminosae): A Review on Pharmacological Properties of Austral South American Species

The genus Bauhinia s.l. (Leguminosae), known as cow's hoof, unha de boi or pata de vaca, has been used in traditional medicine worldwide. The aim of the present review is to summarize the studies published on the biological activity of the main native medicinal species reported in austral South America. Of the 14 species present in the region, 10 are consumed as leaf infusions to regulate glucose and lipid metabolism, as well as used for their anti-inflammatory and analgesic effects and to treat various diseases. Pharmacological properties have been recorded in seven species. Antioxidant, anticoagulant, antihypertensive, diuretic, antimicrobial and antitumor properties have been reported in B. forficata. Together with B. holophylla, they are important for their antidiabetic properties, since several studies indicate their effectiveness as a hypoglycemic agent. B. bauhinioides is distinguished for its anti-inflammatory and antithrombotic activities and S. microstachya for its analgesic properties. Anti-ulcer and wound healing activities recorded in B. holophylla and B. ungulata, respectively, are of particular interest. Most of the species possess antitumor activity. The antioxidant capacity of flavonoids and other bioactive compounds make these plants good candidates to assist or treat various alterations related with oxidative stress, such as diabetic complications. Thus, these species constitute promising targets for new bioactive substance research and phytotherapy.

Plant Kunitz Inhibitors and Their Interaction with Proteases: Current and Potential Pharmacological Targets

The action of proteases can be controlled by several mechanisms, including regulation through gene expression; post-translational modifications, such as glycosylation; zymogen activation; targeting specific compartments, such as lysosomes and mitochondria; and blocking proteolysis using endogenous inhibitors. Protease inhibitors are important molecules to be explored for the control of proteolytic processes in organisms because of their ability to act on several proteases. In this context, plants synthesize numerous proteins that contribute to protection against attacks by microorganisms (fungi and bacteria) and/or invertebrates (insects and nematodes) through the inhibition of proteases in these organisms. These proteins are widely distributed in the plant kingdom, and are present in higher concentrations in legume seeds (compared to other organs and other botanical families), motivating studies on their inhibitory effects in various organisms, including humans. In most cases, the biological roles of these proteins have been assigned based mostly on their in vitro action, as is the case with enzyme inhibitors. This review highlights the structural evolution, function, and wide variety of effects of plant Kunitz protease inhibitors, and their potential for pharmaceutical application based on their interactions with different proteases.

Differences in the Inhibitory Specificity Distinguish the Efficacy of Plant Protease Inhibitors on Mouse Fibrosarcoma

Metastasis, the primary cause of death from malignant tumors, is facilitated by multiple protease-mediated processes. Thus, effort has been invested in the development of protease inhibitors to prevent metastasis. Here, we investigated the effects of protease inhibitors including the recombinant inhibitors rBbKI (serine protease inhibitor) and rBbCI (serine and cysteine inhibitor) derived from native inhibitors identified in Bauhinia bauhinioides seeds, and EcTI (serine and metalloprotease inhibitor) isolated from the seeds of Enterolobium contortisiliquum on the mouse fibrosarcoma model (lineage L929). rBbKI inhibited 80% of cell viability of L929 cells after 48 h, while EcTI showed similar efficacy after 72 h. Both inhibitors acted in a dose and time-dependent manner. Conversely, rBbCI did not significantly affect the viability of L929 cells. Confocal microscopy revealed the binding of rBbKI and EcTI to the L929 cell surface. rBbKI inhibited approximately 63% of L929 adhesion to fibronectin, in contrast with EcTI and rBbCI, which did not significantly interfere with adhesion. None of the inhibitors interfered with the L929 cell cycle phases. The synthetic peptide RPGLPVRFESPL-NH₂, based on the BbKI reactive site, inhibited 45% of the cellular viability of L929, becoming a promising protease inhibitor due to its ease of synthesis.

Biotechnological Potential of Araucaria angustifolia Pine Nuts Extract and the Cysteine Protease Inhibitor AaCI-2S

Protease inhibitors are involved in the regulation of endogenous cysteine proteases during seed development and play a defensive role because of their ability to inhibit exogenous proteases such as those present in the digestive tracts of insects. Araucaria angustifolia seeds, which can be used in human and animal feed, were investigated for their potential for the development of agricultural biotechnology and in the field of human health. In the pine nuts extract, which blocked the activities of cysteine proteases, it was detected potent insecticidal activity against termites (Nasutitermes corniger) belonging to the most abundant termite genus in tropical regions. The cysteine inhibitor (AaCI-2S) was purified by ion-exchange, size exclusion, and reversed-phase chromatography. Its functional and structural stability was confirmed by spectroscopic and circular dichroism studies, and by detection of inhibitory activity at different temperatures and pH values. Besides having activity on cysteine proteases from C. maculatus digestive tract, AaCI-2S inhibited papain, bromelain, ficin, and cathepsin L and impaired cell proliferation in gastric and prostate cancer cell lines. These properties qualify A. angustifolia seeds as a protein source with value properties of natural insecticide and to contain a protease inhibitor with the potential to be a bioactive molecule on different cancer cells.

Purification and Biochemical Characterization of a New Protease Inhibitor from Conyza dioscoridis with Antimicrobial, Antifungal and Cytotoxic Effects

The main objective of the current study was the extraction, purification, and biochemical characterization of a protein protease inhibitor from Conyzadioscoridis. Antimicrobial potential and cytotoxic effects were also examined. The protease inhibitor was extracted in 0.1 M phosphate buffer (pH 6–7). Then, the protease inhibitor, named PDInhibitor, was purified using ammonium sulfate precipitation followed by filtration through a Sephadex G-50 column and had an apparent molecular weight of 25 kDa. The N-terminal sequence of PDInhibitor showed a high level of identity with those of the Kunitz family. PDInhibitor was found to be active at pH values ranging from 5.0 to 11.0, with maximal activity at pH 9.0. It was also fully active at 50 °C and maintained 90% of its stability at over 55 °C. The thermostability of the PDInhibitor was clearly enhanced by CaCl₂ and sorbitol, whereas the presence of Ca²⁺ and Zn²⁺ ions, Sodium taurodeoxycholate (NaTDC), Sodium dodecyl sulfate (SDS), Dithiothreitol (DTT), and β-ME dramatically improved the inhibitory activity. A remarkable affinity of the protease inhibitor with available important therapeutic proteases (elastase and trypsin) was observed. PDInhibitor also acted as a potent inhibitor of commercial proteases from Aspergillus oryzae and of Proteinase K. The inhibitor displayed potent antimicrobial activity against gram+ and gram- bacteria and against fungal strains. Interestingly, PDInhibitor affected several human cancer cell lines, namely HCT-116, MDA-MB-231, and Lovo. Thus, it can be considered a potentially powerful therapeutic agent.

Antitumor activity of Moringa oleifera (drumstick tree) flower trypsin inhibitor (MoFTI) in sarcoma 180-bearing mice

The plant Moringa oleifera is used as food and medicine. M. oleifera flowers are source of protein, fiber, and antioxidants, and are used to treat inflammation and tumors. This work evaluated the antitumor activity of the M. oleifera flower trypsin inhibitor (MoFTI) in sarcoma 180-bearing mice. Swiss female mice were inoculated with sarcoma 180 cells. Seven days later, the animals were treated intraperitoneally for 1 week with daily doses of PBS (control) or MoFTI (15 or 30 mg/kg). For toxicity assessment, water and food consumption, body and organ weights, histological alterations, and blood hematological and biochemical parameters were measured. Treatment with MoFTI caused pronounced reduction (90.1%-97.9%) in tumor weight. The tumors of treated animals had a reduced number of secondary vessels and lower gauge of the primary vessels compared to the control. No significant changes were observed in water and food consumption or in body and organ weights. Histopathological analysis did not indicate damage to the liver, kidneys, and spleen. In conclusion, MoFTI showed antitumor potential, with no clear evidence of toxicity.

4-Deoxyraputindole C induces cell death and cell cycle arrest in tumor cell lines

Several molecules extracted from natural products exhibit different biological activities, such as ion channel modulation, activation of signaling pathways, and anti-inflammatory or antitumor activity. In this study, we tested the antitumor ability of natural compounds extracted from the Raputia praetermissa plant. Among the compounds tested, an alkaloid, here called compound S4 (4-Deoxyraputindole C), showed antitumor effects against human tumor lineages. Compound S4 was the most active against Raji, a lymphoma lineage, promoting cell death with characteristics that including membrane permeabilization, dissipation of the mitochondrial potential, increased superoxide production, and lysosomal membrane permeabilization. The use of cell death inhibitors such as Z-VAD-FMK (caspase inhibitor), necrostatin-1 (receptor-interacting serine/threonine-protein kinase 1 inhibitor), E-64 (cysteine peptidases inhibitor), and N-acetyl- L-cysteine (antioxidant) did not decrease compound S4-dependent cell death. Additionally, we tested the effect of cellular activity on adherent human tumor cells. The highest reduction of cellular activity was observed in A549 cells, a lung carcinoma lineage. In this lineage, the effect on the reduction of the cellular activity was due to cell cycle arrest, without plasma membrane permeabilization, loss of the mitochondrial potential or lysosomal membrane permeabilization. Compound S4 was able to inhibit cathepsin B and L by a nonlinear competitive (negative co-operativity) and simple-linear competitive inhibitions, respectively. The potency of inhibition was higher against cathepsin L. Compound S4 promoted cell cycle arrest at G ₀ and G ₂ phase, and increase the expression of p16 and p21 proteins. In conclusion, compound S4 is an interesting molecule against cancer, promoting cell death in the human lymphoma lineage Raji and cell cycle arrest in the human lung carcinoma lineage A549.

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.

Kallikrein-related peptidases (KLKs) and the hallmarks of cancer

The kallikrein-related peptidases (KLKs) represent the largest family of serine proteases within the human genome and are expressed in various tissues. Although they regulate several important physiological functions, KLKs have also been implicated in numerous pathophysiological processes, including cancer. Growing evidence describing the deregulation of KLK expression and secretion, as well as activation in various malignancies, has uncovered their potential as mediators of cancer progression, biomarkers of disease and as candidate therapeutic targets. The diversity of signalling pathways and proteolytic cascades involving KLKs and their downstream targets appears to affect cancer biology through multiple mechanisms, including those related to the hallmarks of cancer. The aim of this review is to provide an update on the importance of KLK-driven molecular pathways in relation to cancer cell traits associated with the hallmarks of cancer and to highlight their potential in personalized therapeutics.

Overexpression of lipocalins and pro-inflammatory chemokines and altered methylation of PTGS2 and APC2 in oral squamous cell carcinomas induced in rats by 4-nitroquinoline-1-oxide

Oral squamous cell carcinomas (OSCC) induced in F344 rats by 4-nitroquinoline-1-oxide (4-NQO) demonstrate considerable phenotypic similarity to human oral cancers. Gene expression studies (microarray and PCR) were coupled with methylation analysis of selected genes to identify molecular markers of carcinogenesis in this model and potential biochemical and molecular targets for oral cancer chemoprevention. Microarray analysis of 11 pairs of OSCC and site-matched phenotypically normal oral tissues from 4-NQO-treated rats identified more than 3500 differentially expressed genes; 1735 genes were up-regulated in rat OSCC versus non-malignant tissues, while 1803 genes were down-regulated. In addition to several genes involved in normal digestion, genes demonstrating the largest fold increases in expression in 4-NQO-induced OSCC include three lipocalins (VEGP1, VEGP2, LCN2) and three chemokines (CCL, CXCL2, CXCL3); both classes are potentially druggable targets for oral cancer chemoprevention and/or therapy. Down-regulated genes in 4-NQO-induced OSCC include numerous keratins and keratin-associated proteins, suggesting that alterations in keratin expression profiles may provide a useful biomarker of oral cancer in F344 rats treated with 4-NQO. Confirming and extending our previous results, PTGS2 (cyclooxygenase-2) and several cyclooxygenase-related genes were significantly up-regulated in 4-NQO-induced oral cancers; up-regulation of PTGS2 was associated with promoter hypomethylation. Rat OSCC also demonstrated increased methylation of the first exon of APC2; the increased methylation was correlated with down-regulation of this tumor suppressor gene. Overexpression of pro-inflammatory chemokines, hypomethylation of PTGS2, and hypermethylation of APC2 may be causally linked to the etiology of oral cancer in this model.

Bauhinia forficata lectin (BfL) induces cell death and inhibits integrin-mediated adhesion on MCF7 human breast cancer cells

BACKGROUND

Plant lectins have attracted great interest in cancer studies due to their antitumor activities. These proteins or glycoproteins specifically and reversibly bind to different types of carbohydrates or glycoproteins. Breast cancer, which presents altered glycosylation of cell surface glycoproteins, is one of the most frequent malignant diseases in women. In this work, we describe the effect of the lectin Bauhinia forficata lectin (BfL), which was purified from B. forficata Link subsp. forficata seeds, on the MCF7 human breast cancer cellular line, investigating the mechanisms involved in its antiproliferative activity.

METHODS

MCF7 cells were treated with BfL. Viability and adhesion alterations were evaluated using flow cytometry and western blotting.

RESULTS

BfL inhibited the viability of the MCF7 cell line but was ineffective on MDA-MB-231 and MCF 10A cells. It inhibits MCF7 adhesion on laminin, collagen I and fibronectin, decreases α1, α6 and β1 integrin subunit expression, and increases α5 subunit expression. BfL triggers necrosis and secondary necrosis, with caspase-9 inhibition. It also causes deoxyribonucleic acid (DNA) fragmentation, which leads to cell cycle arrest in the G2/M phase and a decrease in the expression of the regulatory proteins pRb and p21.

CONCLUSION

BfL shows selective cytotoxic effect and adhesion inhibition on MCF7 breast cancer cells.

GENERAL SIGNIFICANCE

Cell death induction and inhibition of cell adhesion may contribute to understanding the action of lectins in breast cancer.

The Kallikrein Inhibitor from Bauhinia bauhinioides (BbKI) shows antithrombotic properties in venous and arterial thrombosis models

The Bauhinia bauhinioides Kallikrein Inhibitor (BbKI) is a Kunitz-type serine peptidase inhibitor of plant origin that has been shown to impair the viability of some tumor cells and to feature a potent inhibitory activity against human and rat plasma kallikrein (Kiapp 2.4 nmol/L and 5.2 nmol/L, respectively). This inhibitory activity is possibly responsible for an effect on hemostasis by prolonging activated partial thromboplastin time (aPTT). Because the association between cancer and thrombosis is well established, we evaluated the possible antithrombotic activity of this protein in venous and arterial thrombosis models. Vein thrombosis was studied in the vena cava ligature model in Wistar rats, and arterial thrombosis in the photochemical induced endothelium lesion model in the carotid artery of C57 black 6 mice. BbKI at a concentration of 2.0 mg/kg reduced the venous thrombus weight by 65% in treated rats in comparison to rats in the control group. The inhibitor prolonged the time for total artery occlusion in the carotid artery model mice indicating that this potent plasma kallikrein inhibitor prevented thrombosis.