Plant-derived anticancer agents: a promising treatment for bone metastasis

Natural compounds targeting YAP/TAZ axis in cancer: Current state of art and challenges

Cancer has become a burgeoning global healthcare concern marked by its exponential growth and significant economic ramifications. Though advancements in the treatment modalities have increased the overall survival and quality of life, there are no definite treatments for the advanced stages of this malady. Hence, understanding the diseases etiologies and the underlying molecular complexities, will usher in the development of innovative therapeutics. Recently, YAP/TAZ transcriptional regulation has been of immense interest due to their role in development, tissue homeostasis and oncogenic transformations. YAP/TAZ axis functions as coactivators within the Hippo signaling cascade, exerting pivotal influence on processes such as proliferation, regeneration, development, and tissue renewal. In cancer, YAP is overexpressed in multiple tumor types and is associated with cancer stem cell attributes, chemoresistance, and metastasis. Activation of YAP/TAZ mirrors the cellular "social" behavior, encompassing factors such as cell adhesion and the mechanical signals transmitted to the cell from tissue structure and the surrounding extracellular matrix. Therefore, it presents a significant vulnerability in the clogs of tumors that could provide a wide window of therapeutic effectiveness. Natural compounds have been utilized extensively as successful interventions in the management of diverse chronic illnesses, including cancer. Owing to their capacity to influence multiple genes and pathways, natural compounds exhibit significant potential either as adjuvant therapy or in combination with conventional treatment options. In this review, we delineate the signaling nexus of YAP/TAZ axis, and present natural compounds as an alternate strategy to target cancer.

Antitumor effect of toosendanin on oral squamous cell carcinoma via suppression of p-STAT3

BACKGROUND

Toosendanin (TSN) exhibits potent antitumor activity against various tumor cell lines. However, its efficacy against oral squamous cell carcinoma (OSCC) remains unknown. Here, we investigated the effects of TSN on OSCC cells in vitro and verified them in vivo using a patient-derived xenograft (PDX) model.

METHODS

The effect of TSN on OSCC cells was investigated by cytotoxicity assays and flow cytometry. The expression of proteins was detected by western blotting. An OSCC PDX model was constructed to further investigate the role of TSN in regulating the function of OSCC.

RESULTS

The cell viability of CAL27 and HN6 cells decreased as the concentration of TSN increased within the experimental range. Compared with controls, TSN at lower doses inhibited cell proliferation and induced apoptosis through S-phase cell cycle arrest. TSN inhibited OSCC cell proliferation by downregulating the STAT3 pathway through the inhibition of STAT3 phosphorylation. After successful construction of the OSCC PDX model with high pathological homology to the primary tumor and treatment with an intraperitoneal injection of TSN, we showed that TSN significantly reduced the tumor size of the PDX model mice without obvious toxicity.

CONCLUSIONS

Both in vitro and in vivo, TSN significantly inhibits the proliferation and promoted apoptosis of OSCC cells. Furthermore, TSN demonstrates potent inhibition of STAT3 phosphorylation, indicating its potential as a promising therapeutic agent for OSCC. Therefore, TSN holds great promise as a viable drug candidate for the treatment of OSCC.

Bioactive compounds and functional properties of Rambai (Baccaurea motleyana Müll. Arg.) fruit: A comprehensive review

Rambai (Baccaurea motleyana Müll. Arg.), a member of the Phyllanthaceae family, is one of the underutilized fruits native to Indonesia, Malaya Peninsula, and Thailand. Nowadays, B. motleyana is cultivated for its fruits in many parts of Northern Australia, China, and Southeast Asia. The edible part of the fruit is white and contains reddish arillodes that taste sweet to acid-sweet. The ripe fruit is consumed fresh and can be processed into juice, jams, organic vinegar, and wine. Traditionally, the fruit and its bark are used to treat stomach and eye diseases, respectively. The fruits of B. motleyana are a good source of vitamins, minerals, and fibers, and they also contain bioactive compounds such as phenolic acids, flavonoids, carotenoids, and terpenes. This scientific review describes the nutritional composition, phytochemistry, and pharmacology of B. motleyana. In addition, most recent information is provided to promote the widespread consumption of B. motleyana fruit as well as to create research interest on this interesting species among the scientific community.

Effects of oleuropein on tumor cell growth and bone remodelling: Potential clinical implications for the prevention and treatment of malignant bone diseases

Oleuropein (Ole) is the main bioactive phenolic compound present in olive leaves, fruits and olive oil. This molecule has been shown to exert beneficial effects on several human pathological conditions. In particular, recent preclinical and observational studies have provided evidence that Ole exhibits chemo-preventive effects on different types of human tumors. Studies undertaken to elucidate the specific mechanisms underlying these effects have shown that this molecule may thwart several key steps of malignant progression, including tumor cell proliferation, survival, angiogenesis, invasion and metastasis, by modulating the expression and activity of several growth factors, cytokines, adhesion molecules and enzymes involved in these processes. Interestingly, experimental observations have highlighted the fact that most of these signalling molecules also appear to be actively involved in the homing and growth of disseminating cancer cells in bones and, ultimately, in the development of metastatic bone diseases. These findings, and the experimental and clinical data reporting the preventive activity of Ole on various pathological conditions associated with a bone loss, are indicative of a potential therapeutic role of this molecule in the prevention and treatment of cancer-related bone diseases. This paper provides a current overview regarding the molecular mechanisms and the experimental findings underpinning a possible clinical role of Ole in the prevention and development of cancer-related bone diseases.

A review on traditionally used South African medicinal plants, their secondary metabolites and their potential development into anticancer agents

ETHNOPHARMACOLOGICAL RELEVANCE

Approximately 70% of anticancer drugs were developed or derived from natural products or plants. Southern Africa boasts an enormous floral diversity with approximately 22,755 plant species with an estimated 3000 used as traditional medicines. In South Africa more than 27 million individuals rely on traditional medicine for healthcare. The use of South African plants for the treatment of cancer is poorly documented, however there is potential to develop anticancer agents from these plants. Limited ethnobotanical studies report the use of plants for cancer treatment in traditional medicine. Plants growing in tropical or subtropical regions, such as in South Africa, produce important secondary metabolites as a protective mechanism, which could be used to target various factors that play a key role in carcinogenesis.

AIMS

The aim was to collate information from primary ethnobotanical studies on South African plants traditionally used for the treatment of cancer. Evaluation of literature focused on traditionally used plants that have been tested for their in vitro activity against cancer cells. Secondary metabolites, previously identified within these plant species, were also included for discussion regarding their activity against cancer. The toxicity was evaluated to ascertain the therapeutic potential in further studies. Additionally, the aim was to highlight where a lack of reports were found regarding plant species with potential activity and to substantiate the need for further testing.

MATERIALS AND METHODS

A review of ethnobotanical surveys conducted in South Africa for plants used in the treatment of cancer was performed. Databases such as Science Direct, PubMed and Google Scholar, university repositories of master's dissertations and PhD theses, patents and books were used. Plant species showing significant to moderate activity were discussed regarding their toxicity. Compounds identified within these species were discussed for their activity against cancer cells and toxicity. Traditionally used plants which have not been scientifically validated for their activity against cancer were excluded.

RESULTS

Twenty plants were documented in ethnobotanical surveys as cancer treatments. Numerous scientific reports on the potential in vitro activity against cancer of these plants and the identification of secondary metabolites were found. Many of the secondary metabolites have not been tested for their activity against cancer cells or mode of action and should be considered for future studies. Lead candidates, such as the sutherlandiosides, sutherlandins, hypoxoside and pittoviridoside, were identified and should be further assessed. Toxicity studies should be included when testing plant extracts and/or secondary metabolites for their potential against cancer cells to give an indication of whether further analysis should be conducted.

CONCLUSION

There is a need to document plants used traditionally in South Africa for the treatment of cancer and to assess their safety and efficacy. Traditionally used plants have shown promising activity highlighting the importance of ethnobotanical studies and traditional knowledge. There are many opportunities to further assess these plants and secondary metabolites for their activity against cancer and their toxic effects. Pharmacokinetic studies are also not well documented within these plant extracts and should be included in studies when a lead candidate is identified.

Anticancer Potential of Pulicaria crispa Extract on Human Breast Cancer MDA-MB-231 Cells

Background:

Breast cancer is the common cause of deaths among women globally with 15% mortality globally.

Introduction:

Today, about 80% of the rural population depends on natural products as primary health care. Pulicaria crispa (L., family Compositae) is utilized in traditional medicine for curing colds, coughs, colic, and excessive sweating and as a carminative.

Methods:

The extracts of Pulicaria crispa; grown in Saudi Arabia; were assessed to measure the cytotoxicity with MDA-MB-231 breast cancer cell lines. Soxhlet extraction was utilized for stem, leaves and flower with 70% ethanol. The cytotoxicity of the extracts with MDA-MB-231 breast cancer cells was evaluated by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays.

Results:

The apoptotic cellular morphological alterations were detected by fluorescence microscopes. The results indicated that Pulicaria crispa exhibited a strong anticancer activity with a halfmaximal inhibitory concentration (IC50) of 180 µg/mL against breast cancer cells. The loss in cell integrity, shrinkage of cytoplasm, and cell detachment were seen in the extract treated with MDAMB- 231 cells. The cell death was due to membrane destruction.

Conclusion:

Pulicaria crispa extracts indicated significant cytotoxicity against human breast cancer cells (MDA-MB-231 cells). The extract of this plant may be given to the patients having breast cancer.

Cancer: Thymoquinone antioxidant/pro-oxidant effect as potential anticancer remedy

Recently, there is growing interest in the natural bioactive components having anticancer activity. Thymoquinone (TQ), the principle active constituent of black seed (Nigella sativa), has promising properties including anticancer and chemosensitizing peculiarities. The anticancer power of TQ is accomplished by several aspects; including promotion of apoptosis, arrest of cell cycle and ROS generation. In addition, it boosts the immune system and lessens the side effects associated with traditional anticancer therapy. TQ also controls angiogenesis and cancer metastasis. This review focuses on the potential aspects and mechanisms by which TQ acquires its actions.

Pluronic micelles encapsulated curcumin manifests apoptotic cell death and inhibits pro-inflammatory cytokines in human breast adenocarcinoma cells

BACKGROUND

Curcumin is a natural derivative, which exhibits broad spectrum biological activities including anti-oxidant, anti-inflammatory, and anti-cancer. Since ancient times, it has been used for the treatment of various diseases. Many reports highlighted its potential as a chemopreventive and chemotherapeutic agent. Despite its imperative properties, the pharmacological application had been limited due to low solubility in the aqueous medium, limited tissue absorption, and rapid degradation at physiological pH.

AIMS

Cytotoxicity of drugs and their undesirable side effects are major obstacles in the regimens of cancer therapy. Therefore, natural plant derivatives-based anti-cancer drug delivery systems are getting more attention as they are less toxic, safer, and effective. In the present study, Pluronic block copolymer encapsulated curcumin was developed as an improved curcumin delivery system with the aim to improve its efficacy and biological response against cancer cells.

METHODS AND RESULTS

Pluronic micelles encapsulated curcumin was synthesized, and its characterization was done by particle size analysis, Fourier transform infrared spectroscopy, small-angle neutron scattering analysis, PXRD, and differential scanning calorimetry. Further, its biological activities were corroborated in cancer cells. Results indicate that Pluronic micelles encapsulated curcumin exemplify solubility and stability of curcumin in the aqueous medium. Biophysical characterization indicated that Pluronic F127 forms nanoparticle, and its micellar core radius was increased after incorporation of curcumin. Furthermore, biological studies show that Pluronic micelles encapsulated curcumin inhibits cell proliferation, improves cellular uptake of curcumin, arrests the cell cycle in G0/G1 phase, and inhibits the activation of NF-kB and release of pro-inflammatory cytokines to manifest apoptotic cell death rather than necrotic. This formulation was non-toxic to normal cells.

CONCLUSION

This study suggests that Pluronic micelles encapsulated curcumin is stable that can effectively inhibit cell proliferation and release of pro-inflammatory cytokines in cancer cells as compared with the free curcumin. This approach could be applied to improve the therapeutic index of anti-cancer agents.

Emerging themes of regulation of oncogenic proteins by Solanum nigrum and its bioactive molecules in different cancers

Research over the decades has sequentially and systematically provided a near-complete resolution of multifaceted and therapeutically challenging nature of cancer. Drug discovery from plants has enjoyed a renaissance in the past few years. Natural products have provided many of the lead structures, which are currently being used as templates for the design and synthesis of novel compounds with biologically enhanced properties. With the maturity and diversification of technologies, there is a growing need to design high-throughput functional assays for the evaluation of the myriad of compounds being catalogued. This review sheds light on the tumor suppressive properties of Solanum nigrum and its bioactive ingredients. Several worthy of mention include uttroside B, solanine, solamargine, and physalins, which have been tested for efficacy in cancer cell lines and xenografted mice. We have summarized the most recent findings related to S. nigrum-mediated regulation of intracellular protein network in different cancers. α-Solanine, an active component of S. nigrum, is involved in the regulation of microRNA-21 (miRNA-21) (oncogenic) and miRNA-138 (tumor suppressor) in prostate cancer. However, this is the only available evidence that gives us a clue related to the tumor suppressive effects exerted by components of S. nigrum at a posttranscriptional level. More interestingly, S. nigrum and its components exerted inhibitory effects on different pathways including PI3K/AKT, JAK-STAT, VEGF/VEGFR, and matrix metalloproteinases in different cancers. We also provide an overview of new tools, methodologies, and approaches, which will allow researchers to extract as much information as possible out of the tremendous data sets currently being generated. The use of computational tools will be helpful in processing structurally complex natural products and also in prediction of their macromolecular targets.

Oxidative Stress Modulation and ROS-Mediated Toxicity in Cancer: A Review on In Vitro Models for Plant-Derived Compounds

Medicinal and aromatic plants (MAPs) are known and have been long in use for a variety of health and cosmetics applications. Potential pharmacological usages that take advantage of bioactive plant-derived compounds' antimicrobial, antifungal, anti-inflammatory, and antioxidant properties are being developed and many new ones explored. Some phytochemicals could trigger ROS-mediated cytotoxicity and apoptosis in cancer cells. A lot of effort has been put into investigating novel active constituents for cancer therapeutics. While other plant-derived compounds might enhance antioxidant defenses by either radical scavenging or stimulation of intracellular antioxidant enzymes, the generation of reactive oxygen species (ROS) leading to oxidative stress is one of the strategies that may show effective in damaging cancer cells. The biochemical pathways involved in plant-derived bioactive compounds' properties are complex, and in vitro platforms have been useful for a comprehensive understanding of the mechanism of action of these potential anticancer drugs. The present review aims at compiling the findings of particularly interesting studies that use cancer cell line models for assessment of antioxidant and oxidative stress modulation properties of plant-derived bioactive compounds.

Anticancer potential of Trigonella foenum graecum: Cellular and molecular targets

A growing body of evidence supported by numerous studies on tumorigenesis confirms that it is possible to target various hallmarks of cancer. Recent studies have shown that plant-derived molecules may be used in targeting different signaling pathways for cancer drug discovery. The present paper gives an insight into the anticancer potential of fenugreek and lists the existing studies that have been carried out to demonstrate the advantages of the use of fenugreek in cancer treatment and prevention. It also aims at opening up new perspectives in the development of new drugs of natural origins in the future clinical trials. This review article will discuss; (1) the chemical constituents and bioactive compounds of fenugreek; (2) effects on oxidative stress and inflammation; (3) effects on proliferation, apoptosis, and invasion; (4) toxicity of fenugreek; and 5) future directions in cancer drug development. All of the experimental studies discussed in this paper suggest that multiple signaling pathways (hallmarks) are involved in the anticancer activities of fenugreek, but their efficacy is still unclear, which requires further investigation.

Monitoring ZEO apoptotic potential in 2D and 3D cell cultures and associated spectroscopic evidence on mode of interaction with DNA

Recognizing new anticancer compounds to improve Breast cancer treatment seems crucial. Essential oil of Zataria Multiflora (ZEO) is a secondary metabolite with some biological properties, yet underlying cellular and molecular anticancer properties of ZEO is unclear. GC/MS analysis revealed that carvacrol is the major ingredient of the essential oil. ZEO increasingly suppressed viability in MDA-MB-231, MCF-7 and T47D Breast cancer cells while nontoxic to L929 normal cells in monolayer cell cultures (2D), whereas MDA-MB-231 multicellular spheroids (3D) were more resistant to inhibition. ZEO significantly induced cell apoptosis confirmed by fluorescent staining, flow cytometry analysis and DNA fragmentation in MDA-MB-231 2D and 3D cell cultures. ZEO increased ROS generation and subsequent loss of ΔΨm, caspase 3 activation and DNA damage which consequently caused G1 and G2/M cell cycle arrest in a dose- and time-dependent manner in 2D. S phase arrest occurred in cell spheroids therefore ZEO possible DNA interaction with gDNA was investigated and revealed ZEO binds DNA via intercalation. Altogether, these data corroborate anticancer properties of ZEO and suggest that cell culture format (2D monolayer vs. 3D spheroid) plays a critical role in drug response and provides new insights into the mechanisms underlying ZEO cytotoxicity effect on Breast cancer cells.

Killing cancer with platycodin D through multiple mechanisms

Cancer is a multi-faceted disease comprised of a combination of genetic, epigenetic, metabolic and signalling aberrations which severely disrupt the normal homoeostasis of cell growth and death. Rational developments of highly selective drugs which specifically block only one of the signalling pathways have been associated with limited therapeutic success. Multi-targeted prevention of cancer has emerged as a new paradigm for effective anti-cancer treatment. Platycodin D, a triterpenoid saponin, is one the major active components of the roots of Platycodon grandiflorum and possesses multiple biological and pharmacological properties including, anti-nociceptive, anti-atherosclerosis, antiviral, anti-inflammatory, anti-obesity, immunoregulatory, hepatoprotective and anti-tumour activities. Recently, the anti-cancer activity of platycodin D has been extensively studied. The purpose of this review was to give our perspectives on the current status of platycodin D and discuss its anti-cancer activity and molecular mechanisms which may help the further design and conduct of pre-clinical and clinical trials to develop it successfully into a potential lead drug for oncological therapy. Platycodin D has been shown to fight cancer by inducing apoptosis, cell cycle arrest, and autophagy and inhibiting angiogenesis, invasion and metastasis by targeting multiple signalling pathways which are frequently deregulated in cancers suggesting that this multi-target activity rather than a single effect may play an important role in developing platycodin D into potential anti-cancer drug.

Targeting Apoptosis and Multiple Signaling Pathways with Icariside II in Cancer Cells

Cancer is the second leading cause of deaths worldwide. Despite concerted efforts to improve the current therapies, the prognosis of cancer remains dismal. Highly selective or specific blocking of only one of the signaling pathways has been associated with limited or sporadic responses. Using targeted agents to inhibit multiple signaling pathways has emerged as a new paradigm for anticancer treatment. Icariside II, a flavonol glycoside, is one of the major components of Traditional Chinese Medicine Herba epimedii and possesses multiple biological and pharmacological properties including anti-inflammatory, anti-osteoporosis, anti-oxidant, anti-aging, and anticancer activities. Recently, the anticancer activity of Icariside II has been extensively investigated. Here, in this review, our aim is to give our perspective on the current status of Icariside II, and discuss its natural sources, anticancer activity, molecular targets and the mechanisms of action with specific emphasis on apoptosis pathways which may help the further design and conduct of preclinical and clinical trials. Icariside II has been found to induce apoptosis in various human cancer cell lines of different origin by targeting multiple signaling pathways including STAT3, PI3K/AKT, MAPK/ERK, COX-2/PGE2 and β-Catenin which are frequently deregulated in cancers, suggesting that this collective activity rather than just a single effect may play an important role in developing Icariside II into a potential lead compound for anticancer therapy. This review suggests that Icariside II provides a novel opportunity for treatment of cancers, but additional investigations and clinical trials are still required to fully understand the mechanism of therapeutic effects to further validate it in anti-tumor therapy.