16-Hydroxycleroda-3, 13-dien-15, 16-olide inhibits the proliferation and induces mitochondrial-dependent apoptosis through Akt, mTOR, and MEK-ERK pathways in human renal carcinoma cells

Anticancer diterpenes of African natural products: Mechanistic pathways and preclinical developments

BACKGROUND

The African continent is home to five biodiversity hotspots, boasting an immense wealth of medicinal flora, fungi and marine life. Diterpenes extracted from such natural products have compelling cytotoxic activities that warrant further exploration for the drug market, particularly in cancer therapy, where mortality rates remain elevated worldwide.

PURPOSE

To demonstrate the potential of African natural products on the global stage for cancer therapy development and provide an in-depth analysis of the current literature on the activity of cancer cytotoxic diterpenes from African natural sources (to our knowledge, the first of its kind); not only to reveal the most promising candidates for clinical development, but to demonstrate the importance of preserving the threatened ecosystems of Africa.

METHODS

A comprehensive search by means of the PRISMA strategy was conducted using electronic databases, namely Web of Science, PubMed, Google Scholar and ScienceDirect. The search terms employed were 'diterpene & mechanism & cancer' and 'diterpene & clinical & cancer'. The selection process involved assessing titles in English, Portuguese and Spanish, adhering to predefined eligibility criteria. The timeframe for inclusion spanned from 2010 to 2023, resulting in 218 relevant papers. Chemical structures were visualized using ChemDraw 21.0, PubChem was utilized to search for CID numbers.

RESULTS

Despite being one of the richest biodiverse zones in the world, African natural products are proportionally underreported compared to Asian countries or otherwise. The diterpenes andrographolide (Andrographis paniculata), forskolin (Coleus forskohlii), ent-kauranes from Isodon spp., euphosorophane A (Euphorbia sororia), cafestol & kahweol (Coffea spp.), macrocylic jolkinol D derivatives (Euphorbia piscatoria) and cyathane erinacine A (Hericium erinaceus) illustrated the most encouraging data for further cancer therapy exploration and development.

CONCLUSIONS

Diterpenes from African natural products have the potential to be economically significant active pharmaceutical and medicinal ingredients, specifically focussed on anticancer therapeutics.

Natural products and derivatives in renal, urothelial and testicular cancers: Targeting signaling pathways and therapeutic potential

BACKGROUND

Natural products have demonstrated significant potential in cancer drug discovery, particularly in renal cancer (RCa), urothelial carcinoma (UC), and testicular cancer (TC).

PURPOSE

This review aims to examine the effects of natural products on RCa, UC and TC.

STUDY DESIGN

systematic review METHODS: PubMed and Web of Science databases were retrieved to search studies about the effects of natural products and derivatives on these cancers. Relevant publications in the reference list of enrolled studies were also checked.

RESULTS

This review highlighted their diverse impacts on key aspects such as cell growth, apoptosis, metastasis, therapy response, and the immune microenvironment. Natural products not only hold promise for novel drug development but also enhance the efficacy of existing chemotherapy and immunotherapy. Importantly, we exert their effects through modulation of critical pathways and target genes, including the PI3K/AKT pathway, NF-κB pathway, STAT pathway and MAPK pathway, among others in RCa, UC, and TC.

CONCLUSION

These mechanistic insights provide valuable guidance for researchers, facilitating the selection of promising natural products for cancer management and offering potential avenues for further gene regulation studies in the context of cancer treatment.

Natural Compounds Derived from Plants on Prevention and Treatment of Renal Cell Carcinoma: A Literature Review

Renal cell carcinoma (RCC) accounts for roughly 85% of all malignant kidney cancer. Therapeutic options for RCC have expanded rapidly over the past decade. Targeted therapy and immunotherapy have ushered in a new era of the treatment of RCC, which has facilitated the outcomes of RCC. However, the related adverse effects and drug resistance remain an urgent issue. Natural compounds are optional strategies to reduce mobility. Natural compounds are favored by clinicians and researchers due to their good tolerance and low economic burden. Many studies have explored the anti-RCC activity of natural products and revealed relevant mechanisms. In this article, the chemoprevention and therapeutic potential of natural compounds is reviewed and the mechanisms regarding natural compounds are explored.

Phytochemicals for the Prevention and Treatment of Renal Cell Carcinoma: Preclinical and Clinical Evidence and Molecular Mechanisms

Simple Summary

Renal cell carcinoma (RCC) is the most frequently diagnosed kidney cancer. Once RCC metastasizes, successful treatment is difficult to achieve. There is an apparent need for novel approaches to prevent and treat RCC. Phytochemicals are naturally derived compounds gaining increasing scientific interest due to their cancer preventive and chemotherapeutic properties. These phytochemicals have been shown to exhibit a multitude of anticancer effects against RCC. In this systematic review, we critically evaluate the potential these natural compounds possess for the prevention and treatment of RCC and discuss the future implications this may have in the fight against kidney cancer.

Abstract

Renal cell carcinoma (RCC) is associated with about 90% of renal malignancies, and its incidence is increasing globally. Plant-derived compounds have gained significant attention in the scientific community for their preventative and therapeutic effects on cancer. To evaluate the anticancer potential of phytocompounds for RCC, we compiled a comprehensive and systematic review of the available literature. Our work was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. The literature search was performed using scholarly databases such as PubMed, Scopus, and ScienceDirect and keywords such as renal cell carcinoma, phytochemicals, cancer, tumor, proliferation, apoptosis, prevention, treatment, in vitro, in vivo, and clinical studies. Based on in vitro results, various phytochemicals, such as phenolics, terpenoids, alkaloids, and sulfur-containing compounds, suppressed cell viability, proliferation and growth, showed cytotoxic activity, inhibited invasion and migration, and enhanced the efficacy of chemotherapeutic drugs in RCC. In various animal tumor models, phytochemicals suppressed renal tumor growth, reduced tumor size, and hindered angiogenesis and metastasis. The relevant antineoplastic mechanisms involved upregulation of caspases, reduction in cyclin activity, induction of cell cycle arrest and apoptosis via modulation of a plethora of cell signaling pathways. Clinical studies demonstrated a reduced risk for the development of kidney cancer and enhancement of the efficacy of chemotherapeutic drugs. Both preclinical and clinical studies displayed significant promise of utilizing phytochemicals for the prevention and treatment of RCC. Further research, confirming the mechanisms and regulatory pathways, along with randomized controlled trials, are needed to establish the use of phytochemicals in clinical practice.

Clerodane diterpene induces apoptosis/anoikis and suppresses migration and invasion of human bladder cancer cells through the histone deacetylases, integrin–focal adhesion kinase, and matrix metalloproteinase 9 signalling pathways

Clerodane diterpene, a class of bicyclic diterpenoids, is found in hundreds of plant species. 16-hydroxycleroda-3,13-dien-15,16-olide (CD) can be isolated from the plant Polyalthia longifolia and has been applied against oral cancer and glioma by xenograft model. In this study, we aim to explore its antitumour action by examining its histone deacetylase (HDAC) activity and integrin-associated intracellular signalling pathway on T24 human bladder cancer (BC) cells. Our results revealed that CD-inhibited colony formation, HDAC activity, HDAC (1, 2 and 3) mRNA and cell spreading on fibronectin-coated surfaces in a concentration-dependent manner. Furthermore, decreased cFLIP and increased caspase-8 cleavage accompanied CD-induced cell death. At non-toxic concentrations, CD blocked the migration and invasion of T24 cells. CD hindered migration and invasion by the downregulation of fibronectin, integrin α5 β1, β-catenin, FAK, vinculin and Rho A, as well as by reduction of phosphorylated glycogen synthase kinase 3 β (pGSK3 β), pSrc, pstat3 and pNF κB. We observed that the MMP9 gene was closely linked with prognosis of patients with bladder cancer. MMP9 protein levels and activity were largely attenuated by CD in a concentration-dependent manner. In conclusion, CD-induced caspase-8-dependent apoptosis and suppressed migration and invasion by blocking several intracellular signalling pathways, including downregulation of HDAC activity and integrin–FAK and MMP9 pathways.

Clerodane Diterpenoids from an Edible Plant Justicia insularis: Discovery, Cytotoxicity, and Apoptosis Induction in Human Ovarian Cancer Cells

OBJECTIVES

The toxicity of chemotherapeutic anticancer drugs is a serious issue in clinics. Drug discovery from edible and medicinal plants represents a promising approach towards finding safer anticancer therapeutics. Justicia insularis T. Anderson (Acanthaceae) is an edible and medicinal plant in Nigeria. This study aims to discover cytotoxic compounds from this rarely explored J. insularis and investigate their underlying mechanism of action.

METHODS

The cytotoxicity of the plant extract was evaluated in human ovarian cancer cell lines and normal human ovarian surface epithelia (HOE) cells using a sulforhodamine B assay. Bioassay-guided isolation was carried out using column chromatography including HPLC, and the isolated natural products were characterized using GC-MS, LC-HRMS, and 1D/2D NMR techniques. Induction of apoptosis was evaluated using Caspase 3/7, 8, and 9, and Annexin V and PI based flow cytometry assays. SwissADME and SwissTargetPrediction web tools were used to predict the molecular properties and possible protein targets of identified active compounds. Key finding: The two cytotoxic compounds were identified as clerodane diterpenoids: 16(α/β)-hydroxy-cleroda-3,13(14)Z-dien-15,16-olide (1) and 16-oxo-cleroda-3,13(14)E-dien-15-oic acid (2) from the Acanthaceous plant for the first time. Compound 1 was a very abundant compound (0.7% per dry weight of plant material) and was shown to be more potent than compound 2 with IC₅₀ values in the micromolar range against OVCAR-4 and OVCAR-8 cancer cells. Compounds 1 and 2 were less cytotoxic to HOE cell line. Both compounds induced apoptosis by increasing caspase 3/7 activities in a concentration dependent manner. Compound 1 further increased caspase 8 and 9 activities and apoptosis cell populations. Compounds 1 and 2 are both drug like, and compound 1 may target various proteins including a kinase.

CONCLUSIONS

Clerodane diterpenoids (1 and 2) in J. insularis were identified as cytotoxic to ovarian cancer cells via the induction of apoptosis, providing an abundant and valuable source of hit compounds for the treatment of ovarian cancer.

Phytochemicals from Polyalthia Species: Potential and Implication on Anti-Oxidant, Anti-Inflammatory, Anti-Cancer, and Chemoprevention Activities

Polyalthia belong to the Annonaceae family and are a type of evergreen tree distributed across many tropical and subtropical regions. Polyalthia species have been used long term as indigenous medicine to treat certain diseases, including fever, diabetes, infection, digestive disease, etc. Recent studies have demonstrated that not only crude extracts but also the isolated pure compounds exhibit various pharmacological activities, such as anti-oxidant, anti-microbial, anti-tumor, anti-cancer, etc. It is known that the initiation of cancer usually takes several years and is related to unhealthy lifestyle, as well as dietary and environmental factors, such as stress, toxins and smoking. In fact, natural or synthetic substances have been used as cancer chemoprevention to delay, impede, or even stop cancer growing. This review is an attempt to collect current available phytochemicals from Polyalthia species, which exhibit anti-cancer potentials for chemoprevention purposes, providing directions for further research on the interesting agents and possible clinical applications.

CKS1B as Drug Resistance-Inducing Gene-A Potential Target to Improve Cancer Therapy

Cancer is a threat to human health and life. Although previously centered on chemical drug treatments, cancer treatment has entered an era of precision targeted therapy. Targeted therapy entails precise guidance, allowing the selective killing of cancer cells and thereby reducing damage to healthy tissues. Therefore, the need to explore potential targets for tumor treatment is vital. Cyclin-dependent kinase regulatory subunit 1B (CKS1B), a member of the conserved cyclin kinase subunit 1 (CKS1) protein family, plays an essential role in cell cycling. A large number of studies have shown that CKS1B is associated with the pathogenesis of many human cancers and closely related to drug resistance. Here, we describe the current understanding of the cellular functions of CKS1B and its underlying mechanisms, summarize a recent study of CKS1B as a target for cancer treatment and discuss the potential of CKS1B as a therapeutic target.

16-Hydroxycleroda-3,13-dien-15,16-olide Induces Apoptosis in Human Bladder Cancer Cells through Cell Cycle Arrest, Mitochondria ROS Overproduction, and Inactivation of EGFR-Related Signalling Pathways

A clerodane diterpene compound 16-hydroxycleroda-3,13-dien-15,16-olide (CD) is considered a therapeutic agent with pharmacological activities. The present study investigated the mechanisms of CD-induced apoptosis in T24 human bladder cancer cells. CD inhibited cell proliferation in a concentration and time-dependent manner. CD-induced overproduction of reactive oxygen species and reduced mitochondrial membrane potential, associated with reduced expression of Bcl-2 and increased levels of cytosolic cytochrome c, cleaved PARP-1 and caspase-3. In addition, CD treatment led to cell cycle arrest at the G0/G1 phase and inhibited expression of cyclin D1 and cyclin-dependent kinases 2 and 4 and led to increased levels of p21, p27Kip1 and p53. All of these events were accompanied with a reduction of pEGFR, pMEK1/2, pERK1/2, pAkt, pmTOR, pP70S6K1, HIF-1α, c-Myc and VEGF. RNAseq-based analysis revealed that CD-induced cell death was characterised by an increased expression of stress and apoptotic-related genes as well as inhibition of the cell cycle-related genes. In summary, CD induces apoptosis in T24 bladder cancer cells through targeting multiple intracellular signaling pathways as a result of oxidative stress and cell cycle arrest.

Two clerodane diterpenes isolated from Polyalthia longifolia leaves: comparative structural features, anti-histaminic and anti-Helicobacter pylori activities

Phytochemical studies of methylene chloride soluble fraction from the 70% aqueous-alcoholic extract of Polyalthia longifolia (leaves) resulted in the isolation of two known clerodane diterpenes, namely: 16α-hydroxycleroda-3,13(14)-dien-16,15-olide (1) and (4→2)-abeo-16-hydroxy-cleroda-2,13(14)-dien-15,16-olide-3-al (2). The isolated compounds were evaluated for their anti-histaminic and anti-Helicobacter pylori activities. Compound 1 was more potent than 2 with IC₅₀ 29.7 μg/mL and 189.2 μg/mL in the anti-histaminic assay and MIC equals to 31.25 μg/mL and 125 μg/mL in the anti-H. pylori assay, as compared with diclofenac (IC₅₀ = 17.9 μg/mL) and clarithromycin (MIC = 1.95 μg/mL), respectively. The differences in their structures, as well as their activity results, indicated important characteristic features necessary for activity. It was suggested that the decalin moiety in 1 was important for both activities. On the other hand, the (4→2)-abeo migration in 2 reduced both activities. The potent activities of 1 suggest its potential application as an anti-histaminic and antimicrobial agent.

Polyalthia longifolia leaves methanolic extract targets entry and budding of viruses-an in vitro experimental study against paramyxoviruses

ETHNOPHARMACOLOGICAL RELEVANCE

Synthetic antiviral drugs have several limitations including high cost. Thus research on antiviral property of medicinal plants is continuously gaining importance. Polyalthia longifolia possesses several medicinal properties and has been used in traditional ayurvedic medicine for treatment of dermatological ailments as kushta, visarpa/herpes virus infection and also to treat pyrexia of unknown origin as mentioned in Visarpa Chikitsa.

AIM OF THE STUDY

Keeping in view the cytotoxic, anti-cancer activity and antiviral efficacy of Polyalthia longifolia against herpes, present study was undertaken to evaluate the in vitro antiviral activity of methanolic extract of Polyalthia longifolia leaves, if any, and to unravel the possible target(s)/mechanism of action.

MATERIAL AND METHODS

Antiviral activity of Polyalthia longifolia methanolic extract was studied using Vero cell lines against paramyxoviruses, namely-peste des petits ruminants virus (PPRV) and Newcastle disease virus (NDV). Cytotoxicity of the test extract was evaluated employing MTT assay. Virucidal activity, and viral-attachment, virus entry and release assays were determined in Vero cells using standard experimental protocols. The viral RNA in the virus-infected cells was quantified by qRT-PCR.

RESULTS

At non-cytotoxic concentration, methanolic extract of Polyalthia longifolia leaves was found to inhibit the replication of PPRV and NDV at viral entry and budding level, whereas other steps of viral life cycle such as attachment and RNA synthesis remained unaffected.

CONCLUSIONS

Polyalthia longifolia leaves extract possesses promising antiviral activity against paramyxoviruses and acts by inhibiting the entry and budding of viruses; and this plant extract evidently possesses excellent and promising potential for development of effective herbal antiviral drug.

Clerodane Diterpene Ameliorates Inflammatory Bowel Disease and Potentiates Cell Apoptosis of Colorectal Cancer

Inflammatory bowel disease (IBD) is general term for ulcerative colitis and Crohn's disease, which is chronic intestinal and colorectal inflammation caused by microbial infiltration or immunocyte attack. IBD is not curable, and is highly susceptible to develop into colorectal cancer. Finding agents to alleviate these symptoms, as well as any progression of IBD, is a critical effort. This study evaluates the anti-inflammation and anti-tumor activity of 16-hydroxycleroda-3,13-dien-15,16-olide (HCD) in in vivo and in vitro assays. The result of an IBD mouse model induced using intraperitoneal chemical azoxymethane (AOM)/dextran sodium sulfate (DSS) injection showed that intraperitoneal HCD adminstration could ameliorate the inflammatory symptoms of IBD mice. In the in vitro assay, cytotoxic characteristics and retained signaling pathways of HCD treatment were analyzed by MTT assay, cell cycle analysis, and Western blotting. From cell viability determination, the IC₅₀ of HCD in Caco-2 was significantly lower in 2.30 μM at 48 h when compared to 5-fluorouracil (5-FU) (66.79 μM). By cell cycle and Western blotting analysis, the cell death characteristics of HCD treatment in Caco-2 exhibited the involvement of extrinsic and intrinsic pathways in cell death, for which intrinsic apoptosis was predominantly activated via the reduction in growth factor signaling. These potential treatments against colon cancer demonstrate that HCD could provide a promising adjuvant as an alternative medicine in combating colorectal cancer and IBD.

Fisetin Suppresses the Proliferation and Metastasis of Renal Cell Carcinoma through Upregulation of MEK/ERK-Targeting CTSS and ADAM9

Fisetin, a natural flavonoid, is known to have anticarcinogenic effects against several cancers, but its role in mediating renal cell carcinoma (RCC) progression has not been delineated. Cell viability, cytotoxicity, and cell cycle distribution were measured using the 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and propidium iodide staining with flow cytometry. The in vitro migration and invasion assay was used to examine in vivo cell migration and invasion. Human protease antibody array analysis was conducted with cell migration/invasion-related proteins. Western blotting and quantitative reverse transcription polymerase chain reaction were used for assessing protein expression related to the cell cycle, cell invasion, and mitogen-activated protein kinase (MAPK) signaling pathway. We found that fisetin significantly inhibited cell viability through cell cycle arrest in the G2/M phase, in addition to downregulating cyclin D1 and upregulating p21/p27. Fisetin inhibited the migration and invasion of human RCC cells through the downregulation of CTSS and a disintegrin and metalloproteinase 9 (ADAM9). Fisetin also upregulated ERK phosphorylation in 786-O and Caki-1 cells. Furthermore, treatment with a MEK inhibitor (UO126) reduced the inhibitory effects of fisetin on the metastasis of RCC cells through the ERK/CTSS/ADAM9 pathway. Fisetin inhibits proliferation and metastasis of RCC cells by downregulating CTSS and ADAM9 through the MEK/ERK signaling pathway. These findings indicate that fisetin is a promising antitumor agent against RCC.

Inclusion complex of saikosaponin-d with hydroxypropyl-β-cyclodextrin: Improved physicochemical properties and anti-skin cancer activity

BACKGROUND

Saikosaponin-d (SSD) is a triterpene saponin isolated from Bupleurum plants. It has been shown to exhibit antioxidant, anti-inflammatory, and anticancer activities. However, its biomedical applications are limited by its poor water solubility. Cyclodextrins are highly water soluble oligosaccharide compounds which can form inclusion complexes with lipophilic drugs.

PURPOSE

We complexed SSD with hydroxypropyl-β-cyclodextrin (HPBCD) in various ratios to form SSD-HPBCD inclusion complexes. The inclusion complexes were evaluated for their solubility, physicochemical properties and cytotoxic effects in cutaneous squamous cell carcinoma cells.

METHODS

Surface morphology of pure SSD and SSD-HPBCD inclusion complexes was evaluated by scanning electron microscopy. Crystalline structure was determined by X-ray diffractometry. Intermolecular hydrogen bond formation between SSD and HPBCD was investigated by Fourier transform infrared spectroscopy. Human cutaneous squamous cell carcinoma HSC-1 cell viability was determined by the MTS assay, and cell apoptosis by the caspase 3/7 assay. Signal transduction pathways were investigated by Western blotting.

RESULTS

SSD-HPBCD inclusion complexes showed greatly increased water solubility. This was associated with an improvement in physicochemical properties, including transformation of crystalline structure to amorphous form, and formation of hydrogen bonds between SSD and HPBCD. In addition, SSD-HPBCD inclusion complexes induced apoptosis in HSC-1 cells, and this was mediated through activation of MAPK and suppression of Akt-mTOR signaling pathways.

CONCLUSION

SSD-HPBCD inclusion complex shows improvement in water solubility and physicochemical properties, and exhibits anticancer effects against cutaneous squamous cell carcinoma cells. Therefore, it may be a potential drug formulation for the treatment of skin cancer.

Phellodendrine chloride suppresses proliferation of KRAS mutated pancreatic cancer cells through inhibition of nutrients uptake via macropinocytosis

Despite the massive efforts to develop the treatment of pancreatic cancers, no effective application exhibits satisfactory clinical outcome. Macropinocytosis plays a critical role for continuous proliferation of pancreatic ductal adenocarcinoma (PDAC). In this study, we generated a screening method and identified phellodendrine chloride (PC) as a potential macropinocytosis inhibitor. PC significantly inhibited the viability of KRAS mutant pancreatic cancer cells (PANC-1 and MiaPaCa-2) in a dose-dependent manner; however, it did not affect the wild type KRAS pancreatic cancer cells (BxPC-3). Further experiments indicated that PC reduced the growth of PANC-1 cells through inhibition of macropinocytosis and diminishing the intracellular glutamine level. Disruption of glutamine metabolism led to enhance the reactive oxygen species level and induce mitochondrial membrane potential depolarization in PANC-1 cells. PC treatment caused increased Bax and decreased Bcl-2 expression, along with the activation of cleaved caspase-3, 7, 9 and cleaved-PARP, thus induced mitochondrial apoptosis. Moreover, PC inhibited macropinocytosis in vivo and effectively reduced the growth of PANC-1 xenograft tumors. All together, we demonstrated that inhibition of macropinocytosis might be an effective strategy to treat pancreatic cancers. Thus, PC could be a potential compound with improved therapeutic efficacy in patients with pancreatic cancers.

The medicinal uses, toxicities and anti-inflammatory activity of Polyalthia species (Annonaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Polyalthia is one of the largest and notable genera in Annonaceae family. Polyalthia species have been widely used in folklore medicine for the treatment of rheumatic fever, gastrointestinal ulcer and generalized body pain. Numerous in vitro and in vivo studies on Polyalthia Species have also corroborated the significant anti-inflammatory potential of its extracts and secondary metabolites.

AIM OF THE STUDY

This review is an attempt to assess the anti-inflammatory activity of Polyalthia species by giving critical appraisal and establishing evidences of their traditional uses. Moreover this review will highlight the lead compounds for future drug development that can serve as a potential anti-inflammatory drug with comparative efficacy and minimum side effects.

MATERIALS AND METHODS

An extensive literature review, focusing the anti-inflammatory potential of Polyalthia species was conducted using the following databases:PubMed, ScienceDirect, SpringerLink, Ovid, Scopus and ProQuest, as well as the locally available books, journals and relevant documents. The reference lists of retrieved papers were also searched for additional studies.

RESULTS

The Polyalthia species have shown significant anti-inflammatory activity through various mechanism of action. The most significant anti-inflammatory mechanism includes the inhibition of nuclear factor kappa B (NF-κB), prostaglandins (PGs), pro-inflammatory cytokines, inducible nitric oxide synthase (iNOS) and reactive oxygen species (ROS). The data suggests that hydroxycleroda-3,13-dien-15,16-olide and 16-oxocleroda-3,13-dien-15-oic acid, quercetin, rutin, spinasterol, α-spinasterol, goniothalamin and (-)-5-hydroxygoniothalamin are the most potent anti-inflammatory compounds from Polyalthia species with comparable IC₅₀ with positive controls.

CONCLUSIONS

Numerous pharmacological studies have supported the use of Polyalthia species against pain, rheumatic fever, haemorrhages and inflammation in traditional medicine. Flavonoids, diterpenoids, sterols and styrylpyrones from genus Polyalthia are the most significant class of compounds with potent anti-inflammatory activity. Secondary metabolites from these classes should be brought into further research to fill the gaps of knowledge in pharmacokinetics, pharmacodynamics, bioavailability, and toxicity in order to convert the pre-clinical results into clinical data for further investigation.

Polyalthia Clerodane Diterpene Potentiates Hypoglycemia via Inhibition of Dipeptidyl Peptidase 4

Serine protease dipeptidyl peptidase 4 (DPP-4) is involved in self/non-self-recognition and insulin sensitivity. DPP-4 inhibitors are conventional choices for diabetic treatment; however, side effects such as headache, bronchus infection, and nasopharyngitis might affect the daily lives of diabetic patients. Notably, natural compounds are believed to have a similar efficacy with lower adverse effects. This study aimed to validate the DPP-4 inhibitory activity of clerodane diterpene 16-hydroxycleroda-3,13-dien-15,16-olide (HCD) from Polyalthia longifolia, rutin, quercetin, and berberine, previously selected through molecular docking. The inhibitory potency of natural DPP-4 candidates was further determined by enzymatic, in vitro Caco-2, and ERK/PKA activation in myocyte and pancreatic cells. The hypoglycemic efficacy of the natural compounds was consecutively analyzed by single-dose and multiple-dose administration in diet-induced obese diabetic mice. All the natural-compounds could directly inhibit DPP-4 activity in enzymatic assay and Caco-2 inhibition assay, and HCD showed the highest inhibition of the compounds. HCD down-regulated LPS-induced ERK phosphorylation in myocyte but blocked GLP-1 induced PKA expression. For in vivo tests, HCD showed hypoglycemic efficacy only in single-dose administration. After 28-days administration, HCD exhibited hypolipidemic and hepatoprotective efficacy. These results revealed that HCD performed potential antidiabetic activity via inhibition of single-dose and long-term administrations, and could be a new prospective anti-diabetic drug candidate.

16-Hydroxycleroda-3,13-dien-15,16-olide induces anoikis in human renal cell carcinoma cells: involvement of focal adhesion disassembly and signaling

Background

Clerodane diterpene, 16-hydroxycleroda-3,13-dien-15,16-olide (CD) isolated from Polyalthia longifolia Benth. & Hook. f. var. pendula was found to be a potential apoptotic inducer in human leukemia, lung cancer, and colon cancer cells. However, the molecular mechanism remains elusive in renal system. Thus, in the present study, the regulatory mechanisms of CD-induced apoptosis in clear cell renal cell carcinoma (ccRCC) cells were investigated.

Materials and methods

Cell proliferation was evaluated by colony formation assay and cell cycle analyses. Protein expressions of focal adhesion (FA) related complexes were examined by immunofluorescence staining and Western blot analyses. Cell migration and invasion capabilities of renal cell carcinoma (RCC) cells were determined by wound healing and Transwell assays.

Results

CD inhibited cell colony formations, induced cell arrest at G2/M phase, and increased subG1 cell population both in 786-O and A-498. During CD treatment, the “rounded-up” cells were observed. The immune-staining of phosphorylated focal adhesion kinase (pFAK), vinculin, and paxillin displayed disassembly of the FA. Moreover, disruption of actin stress fibers was noted after CD treatment. Consistent with the findings, the expressions of pSrc, pFAK, FAK, vinculin, vimentin, and paxillin were all downregulated by CD. In addition, CD attenuated cell migration and invasion activities accompanied by the reductions of pNF-κB, matrix metallo-proteinase (MMP)-2, MMP-9 as well as vascular endothelial growth factor expressions.

Conclusion

CD induced cell cycle arrest, FA complex disassembly, and the inactivation of migratory-related signaling pathways to induce apoptosis in ccRCC cells.

PIM Kinases and Their Relevance to the PI3K/AKT/mTOR Pathway in the Regulation of Ovarian Cancer

Ovarian cancer is a medical term that includes a number of tumors with different molecular biology, phenotypes, tumor progression, etiology, and even different diagnosis. Some specific treatments are required to address this heterogeneity of ovarian cancer, thus molecular characterization may provide an important tool for this purpose. On a molecular level, proviral-integration site for Moloney-murine leukemia virus (PIM) kinases are over expressed in ovarian cancer and play a vital role in the regulation of different proteins responsible for this tumorigenesis. Likewise, the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway is also a central regulator of the ovarian cancer. Interestingly, recent research has linked the PIM kinases to the PI3K/AKT/mTOR pathway in several types of cancers, but their connection in ovarian cancer has not been studied yet. Once the exact relationship of PIM kinases with the PI3K/AKT/mTOR pathway is acquired in ovarian cancer, it will hopefully provide effective treatments on a molecular level. This review mainly focuses on the role of PIM kinases in ovarian cancer and their interactions with proteins involved in its progression. In addition, this review suggests a connection between the PIM kinases and the PI3K/AKT/mTOR pathway and their parallel mechanism in the regulation of ovarian cancer.

The Role of Compounds Derived from Natural Supplement as Anticancer Agents in Renal Cell Carcinoma: A Review

Renal Cell Carcinoma (RCC) is the most prominent kidney cancer derived from renal tubules and accounts for roughly 85% of all malignant kidney cancer. Every year, over 60,000 new cases are registered, and about 14,000 people die from RCC. The incidence of this has been increasing significantly in the U.S. and other countries. An increased understanding of molecular biology and the genomics of RCC has uncovered several signaling pathways involved in the progression of this cancer. Significant advances in the treatment of RCC have been reported from agents approved by the Food and Drug Administration (FDA) that target these pathways. These agents have become drugs of choice because they demonstrate clinical benefit and increased survival in patients with metastatic disease. However, the patients eventually relapse and develop resistance to these drugs. To improve outcomes and seek approaches for producing long-term durable remission, the search for more effective therapies and preventative strategies are warranted. Treatment of RCC using natural products is one of these strategies to reduce the incidence. However, recent studies have focused on these chemoprevention agents as anti-cancer therapies given they can inhibit tumor cell grow and lack the severe side effects common to synthetic compounds. This review elaborates on the current understanding of natural products and their mechanisms of action as anti-cancer agents. The present review will provide information for possible use of these products alone or in combination with chemotherapy for the prevention and treatment of RCC.