Anti-tumoral activity of human salivary peptides

Colorectal cancer and inflammatory bowel diseases share common salivary proteomic pathways

Inflammatory bowels diseases (IBD) are high risk conditions for colorectal cancer (CRC). The discovery of IBD and CRC noninvasive protein/peptide biomarkers using saliva and feces was the aim of this study involving 20 controls, 25 IBD (12 Crohn's Disease-CD), 37 CRC. By untargeted proteomic (LTQ-Orbitrap/MS), a total of 152 proteins were identified in saliva. Absent in controls, 73 proteins were present in both IBD and CRC, being mainly related to cell-adhesion, cadherin-binding and enzyme activity regulation (g-Profiler). Among the remaining 79 proteins, 14 were highly expressed in CD and 11 in CRC. These proteins clustered in DNA replication/expression and innate/adaptive immunity. In stool, endogenous peptides from 30 different proteins were identified, two being salivary and CD-associated: Basic Proline-rich Protein 1 (PRBs) and Acidic Proline-rich Phosphoprotein. Biological effects of the PRBs-related peptides GQ-15 and GG-17 found in CD stool were evaluated using CRC cell lines. These peptides induced cell proliferation and activated Erk1/2, Akt and p38 pathways. In conclusion, the salivary proteome unveiled DNA stability and immunity clusters shared between IBD and CRC. Salivary PRB-derived peptides, enriched in CD stool, stimulate CRC cell proliferation and the pro-oncogenic RAS/RAF/MEK/ERK and PI3K/AKT/mTOR pathways suggesting a potential involvement of PRBs in IBD and cancer pathogenesis.

Natural Peptides Inducing Cancer Cell Death: Mechanisms and Properties of Specific Candidates for Cancer Therapeutics

Nowadays, cancer has become the second highest leading cause of death, and it is expected to continue to affect the population in forthcoming years. Additionally, treatment options will become less accessible to the public as cases continue to grow and disease mechanisms expand. Hence, specific candidates with confirmed anticancer effects are required to develop new drugs. Among the novel therapeutic options, proteins are considered a relevant source, given that they have bioactive peptides encrypted within their sequences. These bioactive peptides, which are molecules consisting of 2–50 amino acids, have specific activities when administered, producing anticancer effects. Current databases report the effects of peptides. However, uncertainty is found when their molecular mechanisms are investigated. Furthermore, analyses addressing their interaction networks or their directly implicated mechanisms are needed to elucidate their effects on cancer cells entirely. Therefore, relevant peptides considered as candidates for cancer therapeutics with specific sequences and known anticancer mechanisms were accurately reviewed. Likewise, those features which turn certain peptides into candidates and the mechanisms by which peptides mediate tumor cell death were highlighted. This information will make robust the knowledge of these candidate peptides with recognized mechanisms and enhance their non-toxic capacity in relation to healthy cells and further avoid cell resistance.

Natural Peptides Inducing Cancer Cell Death: Mechanisms and Properties of Specific Candidates for Cancer Therapeutics

Nowadays, cancer has become the second highest leading cause of death, and it is expected to continue to affect the population in forthcoming years. Additionally, treatment options will become less accessible to the public as cases continue to grow and disease mechanisms expand. Hence, specific candidates with confirmed anticancer effects are required to develop new drugs. Among the novel therapeutic options, proteins are considered a relevant source, given that they have bioactive peptides encrypted within their sequences. These bioactive peptides, which are molecules consisting of 2–50 amino acids, have specific activities when administered, producing anticancer effects. Current databases report the effects of peptides. However, uncertainty is found when their molecular mechanisms are investigated. Furthermore, analyses addressing their interaction networks or their directly implicated mechanisms are needed to elucidate their effects on cancer cells entirely. Therefore, relevant peptides considered as candidates for cancer therapeutics with specific sequences and known anticancer mechanisms were accurately reviewed. Likewise, those features which turn certain peptides into candidates and the mechanisms by which peptides mediate tumor cell death were highlighted. This information will make robust the knowledge of these candidate peptides with recognized mechanisms and enhance their non-toxic capacity in relation to healthy cells and further avoid cell resistance.

DNA Related Enzymes as Molecular Targets for Antiviral and Antitumoral Chemotherapy. A Natural Overview of the Current Perspectives

BACKGROUND

The discovery of new chemotherapeutic agents still remains a continuous goal to achieve. DNA polymerases and topoisomerases act in nucleic acids metabolism modulating different processes like replication, mitosis, damage repair, DNA topology and transcription. It has been widely documented that Polymerases serve as molecular targets for antiviral and antitumoral chemotherapy. Furthermore, telomerase is a ribonucleoprotein with exacerbated activity in most of the tumor cell lines, becoming as an emergent target in Cancer treatment.

METHODS

We undertook an exhaustive search of bibliographic databases for peer-reviewed research literature related to the last decade. The characteristics of screened bibliography describe structure activity relationships and show the principal moieties involved. This work tries to summarize the investigation about natural and semi-synthetic products with natural origin with the faculty to inhibit key enzymes that play a crucial role in DNA metabolism.

RESULTS

Eighty-five data references were included in this review, showing natural products widely distributed throughout the plant kingdom and their bioactive properties such as tumor growing inhibitory effects, and anti-AIDS activity.

CONCLUSION

The findings of this review confirm the importance to find new drugs and biologically active natural products, and their potential medicinally useful benefits.

The PBII gene of the human salivary proline-rich protein P-B produces another protein, Q504X8, with an opiorphin homolog, QRGPR

OBJECTIVES

The NCBI gene database and human-transcriptome database for alternative splicing were used to determine the expression of mRNAs for P-B (SMR3B) and variant form of P-B. The translational product from the former mRNA was identified as the protein named P-B, whereas that from the latter has not yet been elucidated. In the present study, we investigated the expression of P-B and its variant form at the protein level.

DESIGN

To identify the variant protein of P-B, (1) cationic proteins with a higher isoelectric point in human pooled whole saliva were purified by a two dimensional liquid chromatography; (2) the peptide fragments generated from the in-solution of all proteins digested with trypsin separated and analyzed by MALDI-TOF-MS; and (3) the presence or absence of P-B in individual saliva was examined by 15% SDS-PAGE.

RESULTS

The peptide sequences (I³⁷PPPYSCTPNMNNCSR⁵², C⁵³HHHHKRHHYPCNYCFCYPK⁷², R⁵⁹HHYPCNYCFCYPK⁷² and H⁶⁰HYPCNYCFCYPK⁷²) present in the variant protein of P-B were identified. The peptide sequence (G⁶PYPPGPLAPPQPFGPGFVPPPPPPPYGPGR³⁶) in P-B (or the variant) and sequence (I³⁷PPPPPAPYGPGIFPPPPPQP⁵⁷) in P-B were identified. The sum of the sequences identified indicated a 91.23% sequence identity for P-B and 79.76% for the variant. There were cases in which P-B existed in individual saliva, but there were cases in which it did not exist in individual saliva.

CONCLUSIONS

The variant protein is produced by excising a non-canonical intron (CC-AC pair) from the 3'-noncoding sequence of the PBII gene. Both P-B and the variant are subject to proteolysis in the oral cavity.

Comparison of patient-derived high and low phosphatidylserine-exposing colorectal carcinoma cells in their interaction with anti-cancer peptides

Current cancer treatment is frequently compromised by severe adverse effects on healthy cells and tissues as well as by the increasing burden of (multi-)drug resistances. Some representatives of small, amphipathic peptides known as host defense peptides possess the potential to overcome these limitations and to evolve as future anti-cancer therapeutics. Peptide NK-2, derived from porcine NK-lysin, was originally discovered due to its broad-spectrum antimicrobial activities. Today, also potent anti-cancer activity is proven and accompanied by low toxicity towards normal human cells. The molecular basis underlying this target selectivity remains rather elusive. Nevertheless, it is presumptive that preferential peptide interactions with surface factors non-abundant on healthy human cells play a key role. Here, we investigated the cytotoxicity of peptide NK-2 and structurally improved anti-cancer variants thereof against two patient-derived colorectal cancer cell lines, exposing high and low levels of phosphatidylserine on their cell surfaces, respectively. Concluding from a range of in vitro tests involving cellular as well as lipid vesicle-based methods, it is proposed that the magnitude of the accessible membrane surface charge is not a primarily decisive factor for selective peptide interactions. Instead, it is suggested that the level of membrane surface-exposed phosphatidylserine is of crucial importance for the activity of peptide NK-2 and enhanced variants thereof in terms of their cancer cell selectivity, the overall efficacy, as well as the underlying mode of action and kinetics. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.

A Review of the Latest Advances in Encrypted Bioactive Peptides from Protein-Rich Waste

Bioactive peptides are considered the new generation of biologically active regulators that not only prevent the mechanism of oxidation and microbial degradation in foods but also enhanced the treatment of various diseases and disorders, thus increasing quality of life. This review article emphasizes recent advances in bioactive peptide technology, such as: (i) new strategies for transforming bioactive peptides from residual waste into added-value products; (ii) nanotechnology for the encapsulation, protection and release of controlled peptides; and (iii) use of techniques of large-scale recovery and purification of peptides aiming at future applications to pharmaceutical and food industries.