Induction of apoptosis by buckwheat trypsin inhibitor in chronic myeloid leukemia K562 cells

SAXS Analysis and Characterization of Anticancer Activity of PNP-UDP Family Protein from Putranjiva roxburghii

A class of plant defense and storage proteins, including Putranjiva roxburghii PNP protein (PRpnp), belongs to PNP-UDP family. The PRpnp and related plant proteins contain a disrupted PNP-UDP domain as revealed in previous studies. In PRpnp, the insert disrupting the domain contains the trypsin inhibitory site. In the present work, we analyzed native PRpnp (nPRpnp) complex formation with trypsin and inosine using SAXS experiments and established its dual functionality. Results indicated a relatively compact nPRpnp:Inosine structure, whereas trypsin complex showed conformational changes/flexibility. nPRpnp also exhibited a strong anti-cancer activity toward breast cancer (MCF-7), prostate cancer (DU-145) and hepatocellular carcinoma (HepG2) cell lines. MCF-7 and DU-145 were more sensitive to nPRpnp treatment as compared to HepG2. However, nPRpnp treatment showed no effect on the viability of HEK293 cells indicating that nPRpnp is specific for targeting the viability of only cancer cells. Further, acridine orange, DAPI and DNA fragmentation studies showed that cytotoxic effect of nPRpnp is mediated through induction of apoptosis as evident from the apoptosis-associated morphological changes and nuclear fragmentation observed after PRpnp treatment of cancer cells. These results suggest that PRpnp has the potential to be used as an anticancer agent. This is first report of anticancer activity as well as SAXS-based analysis for a PNP enzyme with trypsin inhibitory activity.

Antiproliferation of MP12 derived from a fungus, Aphanomyces invadans virulence factor, cysteine-rich trypsin inhibitor on human laryngeal epithelial cells, and in vivo zebrafish embryo model

Peptide-based drug development is an emerging and promising approach in cancer therapeutics. The present study focuses on understanding the mechanism of MP12 peptide (MDNHVCIPLCPP) derived from cysteine-rich trypsin inhibitor protein of virulence factor of pathogenic fungus Aphanomyces invadans. MP12 is involved in antiproliferative activity against the human laryngeal epithelial cell (Hep-2), demonstrated in this study. MP12 sequence showed a significant binding score and has multiple hydrogen bond interactions with the proteins that play a vital role in apoptotic pathways such as Bcl-2, caspase-3, caspase-7, and XIAP. Based on the bioinformatics characterization and molecular docking result, further study was focused on MP12 antiproliferative activity. The peptide showed a dose-dependent inhibition against Hep-2 cell line proliferation, analyzed over MTT and neutral red uptake assays. The IC₅₀ value of the MP12 peptide was calculated based on the antiproliferative property (24.7 ± 0.34 μM). MP12 treated Hep-2 cells showed significant shrinkage in cell morphology compared to untreated cells, inhibiting the cell cycle. The gene expression analysis validated that the MP12 significantly upregulates the caspase-3, caspase-7, and caspase-9 genes. The developmental toxicity study using zebrafish embryos as in vivo model proved that the MP12 is nontoxic. Based on the obtained results, we proposed that the peptide MP12 derived from cysteine-rich trypsin inhibitor protein of virulence molecule of pathogenic fungus have a potential antiproliferative activity. However, further clinical trials need to be focused on the mechanism and therapeutic application against laryngeal cancer.

Healthy and Resilient Cereals and Pseudo-Cereals for Marginal Agriculture: Molecular Advances for Improving Nutrient Bioavailability

With the ever-increasing world population, an extra 1.5 billion mouths need to be fed by 2050 with continuously dwindling arable land. Hence, it is imperative that extra food come from the marginal lands that are expected to be unsuitable for growing major staple crops under the adverse climate change scenario. Crop diversity provides right alternatives for marginal environments to improve food, feed, and nutritional security. Well-adapted and climate-resilient crops will be the best fit for such a scenario to produce seed and biomass. The minor millets are known for their high nutritional profile and better resilience for several abiotic stresses that make them the suitable crops for arid and salt-affected soils and poor-quality waters. Finger millet (Eleucine coracana) and foxtail millet (Setaria italica), also considered as orphan crops, are highly tolerant grass crop species that grow well in marginal and degraded lands of Africa and Asia with better nutritional profile. Another category of grains, called pseudo-cereals, is considered as rich foods because of their protein quality and content, high mineral content, and healthy and balance food quality. Quinoa (Chenopodium quinoa), amaranth (Amaranthus sp.), and buckwheat (Fagopyrum esculentum) fall under this category. Nevertheless, both minor millets and pseudo-cereals are morphologically different, although similar for micronutrient bioavailability, and their grains are gluten-free. The cultivation of these millets can make dry lands productive and ensure future food as well as nutritional security. Although the natural nutrient profile of these crop plant species is remarkably good, little development has occurred in advances in molecular genetics and breeding efforts to improve the bioavailability of nutrients. Recent advances in NGS have enabled the genome and transcriptome sequencing of these millets and pseudo-cereals for the faster development of molecular markers and application in molecular breeding. Genomic information on finger millet (1,196 Mb with 85,243 genes); S. italica, a model small millet (well-annotated draft genome of 420 Mb with 38,801 protein-coding genes); amaranth (466 Mb genome and 23,059 protein-coding genes); buckwheat (genome size of 1.12 Gb with 35,816 annotated genes); and quinoa (genome size of 1.5 Gb containing 54,438 protein-coding genes) could pave the way for the genetic improvement of these grains. These genomic resources are an important first step toward genetic improvement of these crops. This review highlights the current advances and available resources on genomics to improve nutrient bioavailability in these five suitable crops for the sustained healthy livelihood.

Extracellular protease trypsin activates amiloride-insensitive sodium channels in human leukemia cells

Sodium influx is tightly regulated in the cells of blood origin. Amiloride-insensitive sodium channels were identified as one of the main sodium-transporting pathways in leukemia cells. To date, all known regulatory pathways of these channels are coupled with intracellular actin cytoskeleton dynamics. Here, to search for physiological mechanisms controlling epithelial Na⁺ channel (ENaC)-like channels, we utilized leukemia K562 cells as a unique model to examine single channel behavior in a whole-cell patch-clamp experiments. We have shown for the first time that extracellular serine protease trypsin directly activates sodium channels in plasma membrane of K562 cells. The whole-cell single current recordings clearly demonstrate no inhibition of trypsin-activated channels by amiloride or benzamil. Involvement of proteolytic cleavage in channel opening was confirmed in experiments with soybean trypsin inhibitor. More importantly, stabilization of F-actin with intracellular phalloidin did not prevent trypsin-induced channel activation indicating no implication of cytoskeleton rearrangements in stimulatory effect of extracellular protease. Our data reveals a novel mechanism modulating amiloride-insensitive ENaC-like channel activity and integral sodium permeability in leukemia cells.

rBTI reduced β-amyloid-induced toxicity by promoting autophagy-lysosomal degradation via DAF-16 in Caenorhabditis elegans

Alzheimer's disease (AD) is an age-related neurodegenerative disease, of which β-amyloid (Aβ) induced toxicity was suggested as a main cause. Some substances with prolongevity effects have been shown to be protective against AD. In a previous study we demonstrated that a recombinant buckwheat trypsin inhibitor (rBTI) could prolonge the lifespan in Caenorhabditis elegans (C. elegans). Here, we investigated whether rBTI may benefit to mitigate the AD symptom by feeding the AD model C. elegans CL4176. CL4176 is a transgenic C. elegans expressing human Aβ_3-42 in muscle tissue. The results showed that rBTI not only could extend lifespan but also could reduce Aβ toxicity-triggered body paralysis in AD worms. Further study found the accumulation of Aβ was decreased and autophagy-lysosomal degradation pathway was activated in AD worms treated with rBTI. Moreover, the inhibition of autophagy reduced rBTI-mediated paralysis delay. Genetic analyses showed rBTI increased the transcriptional activity of dauer formation abnormal-16 (DAF-16) and the disruption of daf-16 abolished rBTI-mediated protective effect in AD worms. Taken together, these data indicated that rBTI promoted the autophagy-lysosomal degradation pathway to reduce the Aβ-induced toxicity via DAF-16 in an AD model C. elegans, implying that BTI has the potential to protect against AD.

Buckwheat as a Functional Food and Its Effects on Health

Buckwheat (BW) is a gluten-free pseudocereal that belongs to the Polygonaceae family. BW grain is a highly nutritional food component that has been shown to provide a wide range of beneficial effects. Health benefits attributed to BW include plasma cholesterol level reduction, neuroprotection, anticancer, anti-inflammatory, antidiabetic effects, and improvement of hypertension conditions. In addition, BW has been reported to possess prebiotic and antioxidant activities. In vitro and animal studies suggest that BW's bioactive compounds, such as D-chiro-inositol (DCI), BW proteins (BWP), and BW flavonoids (mainly rutin and quercetin) may be partially responsible for the observed effects. The purpose of this paper is to review the recent research regarding the health benefits of BW, in vitro and in vivo, focusing on the specific role of its bioactive compounds and on the mechanisms by which these effects are exerted.

Recombinant Buckwheat Trypsin Inhibitor Induces Mitophagy by Directly Targeting Mitochondria and Causes Mitochondrial Dysfunction in Hep G2 Cells

Mitochondria are essential targets for cancer chemotherapy and other disease treatments. Recombinant buckwheat trypsin inhibitor (rBTI), a member of the potato type I proteinase inhibitor family, was derived from tartary buckwheat extracts. Our results showed that rBTI directly targeted mitochondria and induced mitochondrial fragmentation and mitophagy. This occurs through enhanced depolarization of the mitochondrial membrane potential, increasing reactive oxygen species (ROS) generation associated with the rise of the superoxide dismutase and catalase activity and glutathione peroxidase (GSH) content, and changes in the GSH/oxidized glutathione ratio. Mild and transient ROS induced by rBTI were shown to be important signaling molecules required to induce Hep G2 mitophagy to remove dysfunctional mitochondria. Furthermore, rBTI could directly induce mitochondrial fragmentation. It was also noted that rBTI highly increased colocalization of mitochondria in treated cells compared to nontreated cells. Tom 20, a subunit of the translocase of the mitochondrial outer membrane complex responsible for recognizing mitochondrial presequences, may be the direct target of rBTI.

Anti-tumoral effects of a trypsin inhibitor derived from buckwheat in vitro and in vivo

Native buckwheat, a common component of food products and medicine, has been observed to inhibit cancer cell proliferation in vitro. The aim of the present study was to evaluate the in vitro and in vivo anti-tumoral effects of recombinant buckwheat trypsin inhibitor (rBTI) on hepatic cancer cells and the mechanism of apoptosis involved. Apoptosis in the H22 cell line induced by rBTI was identified using MTT assays, DNA electrophoresis, flow cytometry, morphological observation of the nuclei, measurement of cytochrome C and assessment of caspase activation. It was identified that rBTI decreases cell viability by inducing apoptosis, as evidenced by the formation of apoptotic bodies and DNA fragmentation. rBTI-induced apoptosis occurred in association with mitochondrial dysfunction, leading to the release of cytochrome C from the mitochondria to the cytosol, as well as the activation of caspase-3, -8 and -9. In conclusion, the results of the present study suggested that rBTI specifically inhibited the growth of the H22 hepatic carcinoma cell line in vitro and in vivo in a concentration-dependent and time-dependent manner, while there were minimal effects on the 7702 normal liver cell line. In addition, rBTI‑induced apoptosis in H22 cells was, at least in part, mediated by a mitochondrial pathway via caspase-9.

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.

Germinated Buckwheat extract decreases blood pressure and nitrotyrosine immunoreactivity in aortic endothelial cells in spontaneously hypertensive rats

Thee present study analysed the quantification of rutin in raw buckwheat extract (RBE) and germinated buckwheat extract (GBE) by high performance liquid chromatography (HPLC), and examined changes in body weight, systolic blood pressure (SBP) and nitrotyrosine (a marker for peroxynitrite formation) immunoreactivity in aortic endothelial cells in spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto (WKY) rats after treatment with RBE and GBE for 5 weeks. In the HPLC study, RBE and GBE contained a mean content of rutin of 1.52 +/- 0.21 and 2.92 +/- 0.88 mg/g, respectively. In the 600 mg/kg GBE-treated group, SBP was lower than that in the 600 mg/kg RBE-treated group. The treatment with RBE and/or GBE significantly reduced oxidative damage in aortic endothelial cells by lowering nitrotyrosine immunoreactivity. These results suggest that GBE has an antihypertensive effect and may protect arterial endothelial cells from oxidative stress.