Anti-tumor effects of P-LPK-CPT, a peptide-camptothecin conjugate, in colorectal cancer

Natural-source payloads used in the conjugated drugs architecture for cancer therapy: Recent advances and future directions

Drug conjugates are obtained from tumor-located vectors connected to cytotoxic agents via linkers, which are designed to deliver hyper-toxic payloads directly to targeted cancer cells. These drug conjugates include antibody-drug conjugates (ADCs), peptide-drug conjugates (PDCs), small molecule-drug conjugates (SMDCs), nucleic acid aptamer-drug conjugates (ApDCs), and virus-like drug conjugate (VDCs), which show great therapeutic value in the clinic. Drug conjugates consist of a targeting carrier, a linker, and a payload. Payloads are key therapy components. Cytotoxic molecules and their derivatives derived from natural products are commonly used in the payload portion of conjugates. The ideal payload should have sufficient toxicity, stability, coupling sites, and the ability to be released under specific conditions to kill tumor cells. Microtubule protein inhibitors, DNA damage agents, and RNA inhibitors are common cytotoxic molecules. Among these conjugates, cytotoxic molecules of natural origin are summarized based on their mechanism of action, conformational relationships, and the discovery of new derivatives. This paper also mentions some cytotoxic molecules that have the potential to be payloads. It also summarizes the latest technologies and novel conjugates developed in recent years to overcome the shortcomings of ADCs, PDCs, SMDCs, ApDCs, and VDCs. In addition, this paper summarizes the clinical trials conducted on conjugates of these cytotoxic molecules over the last five years. It provides a reference for designing and developing safer and more efficient conjugates.

QPH-FR: A Novel Quinoa Peptide Enhances Chemosensitivity by Targeting Leucine-Rich Repeat-Containing G Protein-Coupled Receptor 5 in Colorectal Cancer

Chemoresistance is one of the difficulties in the treatment of colorectal cancer (CRC), and the enhanced stemness of tumor cells is the underlying contributing factor. Leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5) is a classical marker of CRC stem cells and can be an important potential target for CRC chemotherapy. Quinoa, a protein-rich plant, offers potential as a source of high-quality active peptides. Novelly, the study obtained quinoa protein hydrolysate (QPH) from whole quinoa grains by simulated digestion. In vivo experiments revealed that the tumor volume in the 5-FU+QPH group decreased from 145.90 ± 13.35 to 94.49 ± 13.05 mm3 in the 5-FU group, suggesting that QPH enhances the chemosensitivity of CRC. Further, the most effective peptide QPH-FR from 631 peptides in QPH was screened by activity prediction, molecular docking, and experimental validation. Mechanistically, QPH-FR competitively suppressed the formation of the LGR5/RSPO1 complex by binding to LGR5, causing RNF43/ZNRF3 to ubiquitinate the FZD receptor, thereby suppressing the Wnt/β-catenin signaling pathway and exerting stemness inhibition. In summary, the study proposes that a novel peptide QPH-FR from quinoa elucidates the mechanism by which QPH-FR targets LGR5 to enhance chemosensitivity, providing theoretical support for the development of chemotherapeutic adjuvant drugs based on plant peptides.

Peptide-functionalized, -assembled and -loaded nanoparticles in cancer therapy

The combination of peptides and nanoparticles in cancer therapy has shown synergistic results. Nanoparticle functionalization with peptides can increase their targeting ability towards tumor cells. In some cases, the peptides can develop self-assembled nanoparticles, in combination with drugs, for targeted cancer therapy. The peptides can be loaded into nanoparticles and can be delivered by other drugs for synergistic cancer removal. Multifunctional types of peptide-based nanoparticles, including pH- and redox-sensitive classes, have been introduced in cancer therapy. The tumor microenvironment remolds, and the acceleration of immunotherapy and vaccines can be provided by peptide nanoparticles. Moreover, the bioimaging and labeling of cancers can be mediated by peptide nanoparticles. Therefore, peptides can functionalize nanoparticles in targeted cancer therapy.

Biological Activity of Natural and Synthetic Peptides as Anticancer Agents

Cancer is one of the leading causes of morbidity and death worldwide, making it a serious global health concern. Chemotherapy, radiotherapy, and surgical treatment are the most used conventional therapeutic approaches, although they show several side effects that limit their effectiveness. For these reasons, the discovery of new effective alternative therapies still represents an enormous challenge for the treatment of tumour diseases. Recently, anticancer peptides (ACPs) have gained attention for cancer diagnosis and treatment. ACPs are small bioactive molecules which selectively induce cancer cell death through a variety of mechanisms such as apoptosis, membrane disruption, DNA damage, immunomodulation, as well as inhibition of angiogenesis, cell survival, and proliferation pathways. ACPs can also be employed for the targeted delivery of drugs into cancer cells. With over 1000 clinical trials using ACPs, their potential for application in cancer therapy seems promising. Peptides can also be utilized in conjunction with imaging agents and molecular imaging methods, such as MRI, PET, CT, and NIR, improving the detection and the classification of cancer, and monitoring the treatment response. In this review we will provide an overview of the biological activity of some natural and synthetic peptides for the treatment of the most common and malignant tumours affecting people around the world.

Oxime-Linked Peptide-Daunomycin Conjugates as Good Tools for Selection of Suitable Homing Devices in Targeted Tumor Therapy: An Overview

Chemotherapy is still one of the main therapeutic approaches in cancer therapy. Nevertheless, its poor selectivity causes severe toxic side effects that, together with the development of drug resistance in tumor cells, results in a limitation for its application. Tumor-targeted drug delivery is a possible choice to overcome these drawbacks. As well as monoclonal antibodies, peptides are promising targeting moieties for drug delivery. However, the development of peptide-drug conjugates (PDCs) is still a big challenge. The main reason is that the conjugates have to be stable in circulation, but the drug or its active metabolite should be released efficiently in the tumor cells. For this purpose, suitable linker systems are needed that connect the drug molecule with the homing peptide. The applied linker systems are commonly categorized as cleavable and non-cleavable linkers. Both the groups possess advantages and disadvantages that are summarized briefly in this manuscript. Moreover, in this review paper, we highlight the benefit of oxime-linked anthracycline-peptide conjugates in the development of PDCs. For instance, straightforward synthesis as well as a conjugation reaction proceed in excellent yields, and the autofluorescence of anthracyclines provides a good tool to select the appropriate homing peptides. Furthermore, we demonstrate that these conjugates can be used properly in in vivo studies. The results indicate that the oxime-linked PDCs are potential candidates for targeted tumor therapy.

Identification of molecular pattern and prognostic risk model based on ligand-receptor pairs in liver cancer

Introduction

The tumor microenvironment of hepatocellular carcinoma is composed of multiple cells, and the interactive communication between cells drives tumor progression and characterizes the tumor. Communication between cells is mainly achieved through signal transduction between receptor ligands, and the rise of single-cell technology has made it possible to analyze the communication network between cells.

Methods

We applied a train of bioinformatic techniques and in vitro experiments. We analyzed the composition of the microenvironment of liver cancer by combining single-cell sequencing data and transcriptome sequencing data from liver cancer to construct molecular typing and risk models for LRs. Then, we analyzed association of it with prognosis, mutation, KEGG, tumor microenvironment (TME), immune infiltration, tumor mutational burden (TMB) and drug sensitivity in liver cancer. qPCR and was used to identify SLC1A5 expression in LIHC cell lines and CCK8, transwell and cell colony formation were performed to validate the function of SLC1A5. Meanwhile, we also performed polarization of macrophages.

Results

In this experiment, we found that liver cancer tissues are rich in immune and mesenchymal cells, and there is extensive signaling between individual cells, so we constructed molecular typing and risk models for LRs. Combining clinical data revealed significant differences in clinical characteristics, prognosis and mutated genes between the molecular typing of receptor-ligand pairs, as well as in sensitivity to drugs; similarly, there were significant prognostic differences between the risk models. There were also notable differences in activated signaling pathways, infiltrating immune cells and immune subtypes. Subsequently, we used siRNA to knock down SLC1A5 in hepatocellular carcinoma cells and found that cell proliferation, migration and invasion were diminished.

Conclusions

In conclusion, our LRs model may become a marker to guide clinical treatment and prognosis.

A link between STK signalling and capsular polysaccharide synthesis in Streptococcus suis

Synthesis of capsular polysaccharide (CPS), an important virulence factor of pathogenic bacteria, is modulated by the CpsBCD phosphoregulatory system in Streptococcus. Serine/threonine kinases (STKs, e.g. Stk1) can also regulate CPS synthesis, but the underlying mechanisms are unclear. Here, we identify a protein (CcpS) that is phosphorylated by Stk1 and modulates the activity of phosphatase CpsB in Streptococcus suis, thus linking Stk1 to CPS synthesis. The crystal structure of CcpS shows an intrinsically disordered region at its N-terminus, including two threonine residues that are phosphorylated by Stk1. The activity of phosphatase CpsB is inhibited when bound to non-phosphorylated CcpS. Thus, CcpS modulates the activity of phosphatase CpsB thereby altering CpsD phosphorylation, which in turn modulates the expression of the Wzx-Wzy pathway and thus CPS production.