The function of natural compounds in important anticancer mechanisms

Immunogenic cell death inducers for cancer therapy: An emerging focus on natural products

BACKGROUND

Immunogenic cell death (ICD) is a specific form of regulated cell death induced by a variety of stressors. During ICD, the dying cancer cells release damage-associated molecular patterns (DAMPs), which promote dendritic cell maturation and tumor antigen presentation, subsequently triggering a T-cell-mediated anti-tumor immune response. In recent years, a growing number of studies have demonstrated the potential of natural products to induce ICD and enhance tumor cell immunogenicity. Moreover, there is an increasing interest in identifying new ICD inducers from natural products.

PURPOSE

This study aimed to emphasize the potential of natural products and their derivatives as ICD inducers to promote research on using natural products in cancer therapy and provide ideas for future novel immunotherapies based on ICD induction.

METHOD

This review included a thorough search of the PubMed, Web of Science, Scopus, and Google Scholar databases to identify natural products with ICD-inducing capabilities. A comprehensive search for clinical trials on natural ICD inducers was also conducted using ClinicalTrials.gov, as well as the approved patents using the Espacenet and CNKI Patent Database.

RESULTS

Natural compounds that induce ICD can be categorized into several groups, such as polyphenols, flavonoids, terpenoids, and alkaloids. Natural products can induce the release of DAMPs by triggering endoplasmic reticulum stress, activation of autophagy-related pathways, and reactive oxygen species generation, etc. Ultimately, they activate anti-tumor immune response and improve the efficacy of cancer treatments.

CONCLUSION

A growing number of ICD inducers from natural products with promising anti-cancer potential have been identified. The detailed information presented in this review will contribute to the further development of natural ICD inducers and cancer treatment strategies based on ICD-induced responses.

Implication of Caffeic Acid for the Prevention and Treatment of Alzheimer's Disease: Understanding the Binding with Human Transferrin Using In Silico and In Vitro Approaches

In present times, a switch from chemical molecules towards natural products is taking place, and the latter is being increasingly explored in the management of diseases due to their broad range of therapeutic potential. Consumption of coffee is thought to reduce Alzheimer's disease (AD); however, the mechanism is still unexplored. Primarily, it is thought that components of coffee are the key players in making it a neuroprotectant. Caffeic acid (CA) is found in high quantities in coffee; thus, it is being increasingly explored to decipher its neuroprotection by various mechanisms. Iron is a toxic element in a free form capable of causing oxidative damage and ultimately contributing to the pathogenesis of AD. Thus, maintaining the proper iron levels is vital and human transferrin (Htf), a glycoprotein, is a key player in this aspect. In this work, we explored the binding mechanism of CA with Htf at the atomistic level, employing molecular docking and extensive molecular dynamics simulation (MD) approaches coupled with spectroscopic techniques in a bid to decipher the mode of interaction of CA with Htf. Molecular docking results demonstrated a strong binding affinity between CA and Htf. Furthermore, MD study highlighted the Htf-CA complex's stability and the ligand's minimal impact on Htf's overall structure. In silico approaches were further backed up by experimental approaches. Strong binding of CA with Htf was ascertained by UV-visible and fluorescence spectroscopy observations. Together, the study provides a comprehensive understanding of the Htf-CA interaction, adding to the knowledge of the use of CA in the treatment of AD, thereby adding another feather to its already known neuroprotective role.

Exploring MTH1 inhibitory potential of Thymoquinone and Baicalin for therapeutic targeting of breast cancer

Cancers frequently have increased ROS levels due to disrupted redox balance, leading to oxidative DNA and protein damage, mutations, and apoptosis. The MTH1 protein plays a crucial role by sanitizing the oxidized dNTP pools. Hence, cancer cells rely on MTH1 to prevent the integration of oxidized dNTPs into DNA, preventing DNA damage and allowing cancer cell proliferation. We have discovered Thymoquinone (TQ) and Baicalin (BC) as inhibitors of MTH1 using combined docking and MD simulation approaches complemented by experimental validations via assessing binding affinity and enzyme inhibition. Docking and MD simulations studies revealed an efficient binding of TQ and BC to the active site pocket of the MTH1, and the resultant complexes are appreciably stable. Fluorescence measurements estimated a strong binding affinity of TQ and BC with Ka 3.4 ×106 and 1.0 ×105, respectively. Treating breast cancer cells with TQ and BC significantly inhibited the growth and proliferation (IC50 values 28.3 µM and 34.8 µM) and induced apoptosis. TQ and BC increased the ROS production in MCF7 cells, imposing substantial oxidative stress on cancer cells and leading to cell death. Finally, TQ and BC are proven strong MTH1 inhibitors, offering promising prospects for anti-cancer therapy.

Identification of anti-gastric cancer effects and molecular mechanisms of resveratrol: From network pharmacology and bioinformatics to experimental validation

BACKGROUND

Gastric cancer (GC) is one of the most aggressive malignancies with limited therapeutic options and a poor prognosis. Resveratrol, a non-flavonoid polyphenolic compound found in a variety of Chinese medicinal materials, has shown excellent anti-GC effect. However, its exact mechanisms of action in GC have not been clarified.

AIM

To identify the effects of resveratrol on GC progression and explore the related molecular mechanisms.

METHODS

Action targets of resveratrol and GC-related targets were screened from public databases. The overlapping targets between the two were confirmed using a Venn diagram, and a "Resveratrol-Target-GC" network was constructed using Cytoscape software version 3.9.1. The protein-protein interaction (PPI) network was constructed using STRING database and core targets were identified by PPI network analysis. The Database for Annotation, Visualization and Integrated Discovery database was used for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. A "Target-Pathway" network was created by using Cytoscape 3.9.1. The RNA and protein expression levels of core target genes were observed using the Cancer Genome Atlas and the Human Protein Atlas databases. DriverDBv3 and Timer2.0 databases were used for survival and immune infiltration analysis. Subsequently, the findings were further verified by molecular docking technology and in vitro experiments.

RESULTS

A total of 378 resveratrol action targets and 2154 GC disease targets were obtained from public databases, and 181 intersection targets between the two were screened by Venn diagram. The top 20 core targets were identified by PPI network analysis of the overlapping targets. GO function analysis mainly involved protein binding, identical protein binding, cytoplasm, nucleus, negative regulation of apoptotic process and response to xenobiotic stimulus. KEGG enrichment analysis suggested that the involved signaling pathways mainly included PI3K-AKT signaling pathway, MAPK signaling pathway, IL-17 signaling pathway, TNF signaling pathway, ErbB signaling pathway, etc. FBJ murine osteosarcoma viral oncogene homolog (FOS) and matrix metallopeptidase 9 (MMP9) were selected by differential expression analysis, and they were closely associated with immune infiltration. Molecular docking results showed that resveratrol docked well with these two targets. Resveratrol treatment arrested the cell cycle at the S phase, induced apoptosis, and weakened viability, migration and invasion in a dose-dependent manner. Furthermore, resveratrol could exhibit anti-GC effect by regulating FOS and MMP9 expression.

CONCLUSION

The anti-GC effects of resveratrol are related to the inhibition of cell proliferation, migration, invasion and induction of cell cycle arrest and apoptosis by targeting FOS and MMP9.

Anticancer Drug Discovery Based on Natural Products: From Computational Approaches to Clinical Studies

Globally, malignancies cause one out of six mortalities, which is a serious health problem. Cancer therapy has always been challenging, apart from major advances in immunotherapies, stem cell transplantation, targeted therapies, hormonal therapies, precision medicine, and palliative care, and traditional therapies such as surgery, radiation therapy, and chemotherapy. Natural products are integral to the development of innovative anticancer drugs in cancer research, offering the scientific community the possibility of exploring novel natural compounds against cancers. The role of natural products like Vincristine and Vinblastine has been thoroughly implicated in the management of leukemia and Hodgkin's disease. The computational method is the initial key approach in drug discovery, among various approaches. This review investigates the synergy between natural products and computational techniques, and highlights their significance in the drug discovery process. The transition from computational to experimental validation has been highlighted through in vitro and in vivo studies, with examples such as betulinic acid and withaferin A. The path toward therapeutic applications have been demonstrated through clinical studies of compounds such as silvestrol and artemisinin, from preclinical investigations to clinical trials. This article also addresses the challenges and limitations in the development of natural products as potential anti-cancer drugs. Moreover, the integration of deep learning and artificial intelligence with traditional computational drug discovery methods may be useful for enhancing the anticancer potential of natural products.

The Nexus of Inflammation-Induced Epithelial-Mesenchymal Transition and Lung Cancer Progression: A Roadmap to Pentacyclic Triterpenoid-Based Therapies

Lung cancer is the leading cause of cancer-related death worldwide. Its high mortality is partly due to chronic inflammation that accompanies the disease and stimulates cancer progression. In this review, we analyzed recent studies and highlighted the role of the epithelial-mesenchymal transition (EMT) as a link between inflammation and lung cancer. In the inflammatory tumor microenvironment (iTME), fibroblasts, macrophages, granulocytes, and lymphocytes produce inflammatory mediators, some of which can induce EMT. This leads to increased invasiveness of tumor cells and self-renewal of cancer stem cells (CSCs), which are associated with metastasis and tumor recurrence, respectively. Based on published data, we propose that inflammation-induced EMT may be a potential therapeutic target for the treatment of lung cancer. This prospect is partially realized in the development of EMT inhibitors based on pentacyclic triterpenoids (PTs), described in the second part of our study. PTs reduce the metastatic potential and stemness of tumor cells, making PTs promising candidates for lung cancer therapy. We emphasize that the high diversity of molecular mechanisms underlying inflammation-induced EMT far exceeds those that have been implicated in drug development. Therefore, analysis of information on the relationship between the iTME and EMT is of great interest and may provide ideas for novel treatment approaches for lung cancer.

In-silico and in-vitro assessments of some fabaceae, rhamnaceae, apocynaceae, and anacardiaceae species against Mycobacterium tuberculosis H37Rv and triple-negative breast cancer cells

Medicinal plants play a huge role in the treatment of various diseases in the Limpopo province (South Africa). Traditionally, concoctions used for treating tuberculosis and cancer are sometimes prepared from plant parts naturally occurring in the region, these include (but not limited to) Schotia brachypetala, Rauvolfia caffra, Schinus molle, Ziziphus mucronate, and Senna petersiana. In this study, the aim was to evaluate the potential antimycobacterial activity of the five medicinal plants against Mycobacterium smegmatis mc²155, Mycobacterium aurum A + , and Mycobacterium tuberculosis H37Rv, and cytotoxic activity against MDA-MB 231 triple-negative breast cancer cells. Phytochemical constituents present in R. caffra and S. molle were tentatively identified by LC-QTOF-MS/MS as these extracts showed antimycobacterial and cytotoxic activity. A rigorous Virtual Screening Workflow (VSW) of the tentatively identified phytocompounds was then employed to identify potential inhibitor/s of M. tuberculosis pantothenate kinase (PanK). Molecular dynamics simulations and post-MM-GBSA free energy calculations were used to determine the potential mode of action and selectivity of selected phytocompounds. The results showed that plant crude extracts generally exhibited poor antimycobacterial activity, except for R. caffra and S. molle which exhibited average efficacy against M. tuberculosis H37Rv with minimum inhibitory concentrations between 0.25-0.125 mg/mL. Only one compound with a favourable ADME profile, namely, norajmaline was returned from the VSW. Norajmaline exhibited a docking score of -7.47 kcal/mol, while, pre-MM-GBSA calculation revealed binding free energy to be -37.64 kcal/mol. All plant extracts exhibited a 50% inhibitory concentration (IC₅₀) of < 30 μg/mL against MDA-MB 231 cells. Flow cytometry analysis of treated MDA-MB 231 cells showed that the dichloromethane extracts from S. petersiana, Z. mucronate, and ethyl acetate extracts from R. caffra and S. molle induced higher levels of apoptosis than cisplatin. It was concluded that norajmaline could emerge as a potential antimycobacterial lead compound. Validation of the antimycobacterial activity of norajmaline will need to be performed in vitro and in vivo before chemical modifications to enhance potency and efficacy are done. S. petersiana, Z. mucronate, R.caffra and S. molle possess strong potential as key contributors in developing new and effective treatments for triple-negative breast cancer in light of the urgent requirement for innovative therapeutic solutions.

A Deadly Liaison between Oxidative Injury and p53 Drives Methyl-Gallate-Induced Autophagy and Apoptosis in HCT116 Colon Cancer Cells

Methyl gallate (MG), which is a gallotannin widely found in plants, is a polyphenol used in traditional Chinese phytotherapy to alleviate several cancer symptoms. Our studies provided evidence that MG is capable of reducing the viability of HCT116 colon cancer cells, while it was found to be ineffective on differentiated Caco-2 cells, which is a model of polarized colon cells. In the first phase of treatment, MG promoted both early ROS generation and endoplasmic reticulum (ER) stress, sustained by elevated PERK, Grp78 and CHOP expression levels, as well as an upregulation in intracellular calcium content. Such events were accompanied by an autophagic process (16-24 h), where prolonging the time (48 h) of MG exposure led to cellular homeostasis collapse and apoptotic cell death with DNA fragmentation and p53 and γH2Ax activation. Our data demonstrated that a crucial role in the MG-induced mechanism is played by p53. Its level, which increased precociously (4 h) in MG-treated cells, was tightly intertwined with oxidative injury. Indeed, the addition of N-acetylcysteine (NAC), which is a ROS scavenger, counteracted the p53 increase, as well as the MG effect on cell viability. Moreover, MG promoted p53 accumulation into the nucleus and its inhibition by pifithrin-α (PFT-α), which is a negative modulator of p53 transcriptional activity, enhanced autophagy, increased the LC3-II level and inhibited apoptotic cell death. These findings provide new clues to the potential action of MG as a possible anti-tumor phytomolecule for colon cancer treatment.

Insights on the Role of Polyphenols in Combating Cancer Drug Resistance

Chemotherapy resistance is still a serious problem in the treatment of most cancers. Many cellular and molecular mechanisms contribute to both inherent and acquired drug resistance. They include the use of unaffected growth-signaling pathways, changes in the tumor microenvironment, and the active transport of medicines out of the cell. The antioxidant capacity of polyphenols and their potential to inhibit the activation of procarcinogens, cancer cell proliferation, metastasis, and angiogenesis, as well as to promote the inhibition or downregulation of active drug efflux transporters, have been linked to a reduced risk of cancer in epidemiological studies. Polyphenols also have the ability to alter immunological responses and inflammatory cascades, as well as trigger apoptosis in cancer cells. The discovery of the relationship between abnormal growth signaling and metabolic dysfunction in cancer cells highlights the importance of further investigating the effects of dietary polyphenols, including their ability to boost the efficacy of chemotherapy and avoid multidrug resistance (MDR). Here, it is summarized what is known regarding the effectiveness of natural polyphenolic compounds in counteracting the resistance that might develop to cancer drugs as a result of a variety of different mechanisms.

The Role of NQO1 in Ovarian Cancer

Ovarian cancer is one of the most dangerous gynecologic malignancies showing a high fatality rate because of late diagnosis and relapse occurrence due to chemoresistance onset. Several researchers reported that oxidative stress plays a key role in ovarian cancer occurrence, growth and development. The NAD(P)H:quinone oxidoreductase 1 (NQO1) is an antioxidant enzyme that, using NADH or NADPH as substrates to reduce quinones to hydroquinones, avoids the formation of the highly reactive semiquinones, then protecting cells against oxidative stress. In this review, we report evidence from the literature describing the effect of NQO1 on ovarian cancer onset and progression.

Current understanding of plant-derived exosome-like nanoparticles in regulating the inflammatory response and immune system microenvironment

Natural compounds are widely used to prevent and treat various diseases due to their antioxidant and anti-inflammatory effects. As a kind of promising natural compound, plant-derived exosome-like nanoparticles (PELNs) are extracted from multivesicular bodies of various edible plants, including vegetables, foods, and fruits, and mainly regulate the cellular immune response to pathogen attacks. Moreover, PELNs could remarkably interfere with the dynamic imbalance between pro-inflammatory and anti-inflammatory effects, facilitating to maintain the homeostasis of cellular immune microenvironment. PELNs may serve as a better alternative to animal-derived exosomes (ADEs) owing to their widespread sources, cost-effectiveness, and easy accessibility. PELNs can mediate interspecies communication by transferring various cargoes such as proteins, lipids, and nucleic acids from plant cells to mammalian cells. This review summarizes the biogenesis, composition, and classification of exosomes; the common separation, purification, and characterization methods of PELNs, the potential advantages of PELNs over ADEs; and the anti-inflammatory and immunomodulatory functions of PELNs in various diseases including colitis, cancer, and inflammation-associated metabolic diseases. Additionally, the future perspectives of PELNs and the challenges associated with their clinical application are discussed.