Anticancer activity of ursolic acid on retinoblastoma cells determined by bioinformatics analysis and validation

An Update on Pentacyclic Triterpenoids Ursolic and Oleanolic Acids and Related Derivatives as Anticancer Candidates

Cancer is a global health problem, with the incidence rate estimated to reach 40% of the population by 2030. Although there are currently several therapeutic methods, none of them guarantee complete healing. Plant-derived natural products show high therapeutic potential in the management of various types of cancer, with some of them already being used in current practice. Among different classes of phytocompounds, pentacyclic triterpenoids have been in the spotlight of research on this topic. Ursolic acid (UA) and its structural isomer, oleanolic acid (OA), represent compounds intensively studied and tested in vitro and in vivo for their anticancer and chemopreventive properties. Since natural compounds can rarely be used in practice as such due to their characteristic physico-chemical properties, to tackle this problem, their derivatization has been attempted, obtaining compounds with improved solubility, absorption, stability, effectiveness, and reduced toxicity. This review presents various UA and OA derivatives that have been synthesized and evaluated in recent studies for their anticancer potential. It can be observed that the most frequent structural transformations were carried out at the C-3, C-28, or both positions simultaneously. It has been demonstrated that conjugation with heterocycles or cinnamic acid, derivatization as hydrazide, or transforming OH groups into esters or amides increases anticancer efficacy.

Synthesis and Structural Activity Relationship Study of Ursolic Acid Derivatives as Antitubercular Agent

OBJECTIVE

The chemical transformation of ursolic acid (UA) into novel C-3 aryl ester derivatives and in vitro and silico assessment of their antitubercular potential.

BACKGROUND

UA is a natural pentacyclic triterpenoid with many pharmacological properties. Semisynthetic UA analogs have demonstrated enhanced anticancer, antimalarial, and antifilarial properties in our previous studies.

METHODS

The C-30 carboxylic group of previously isolated UA was protected, and various C-3 aryl ester derivatives were semi-synthesized. The agar dilution method was used to evaluate the in vitro antitubercular efficacy of Mycobacterium tuberculosis (Mtb) H37Ra. In silico docking studies of the active derivative were carried out against Mtb targets, catalase peroxidase (PDB: 1SJ2), dihydrofolate reductase (PDB: 4M2X), enoyl-ACP reductase (PDB: 4TRO), and cytochrome bc1 oxidase (PDB: 7E1V).

RESULTS

The derivative 3-O-(2-amino,3-methyl benzoic acid)-ethyl ursolate (UA-1H) was the most active among the eight derivatives (MIC1 2.5 μg/mL) against Mtb H37Ra. Also, UA-1H demonstrated significant binding affinity in the range of 10.8-11.4 kcal/mol against the antiTb target proteins, which was far better than the positive control Isoniazid, Ethambutol, and co-crystallized ligand (HEM). Moreover, the predicted hit UA-1H showed no inhibition of Cytochrome P450 2D6 (CYP2D6), suggesting its potential for favorable metabolism in Phase I clinical studies.

CONCLUSION

The ursolic acid derivative UA-1H possesses significant in vitro antitubercular potential with favorable in silico pharmacokinetics. Hence, further in vivo assessments are suggested for UA-1H for its possible development into a secure and efficient antitubercular drug.

MiR-452-5p facilitates retinoblastoma cell growth and invasion via the SOCS3/JAK2/STAT3 pathway

Retinoblastoma (RB) is an intraocular tumor in children. Accumulated evidence confirms that microRNAs (miRNAs) exert critical functions in RB. This research aimed to investigate the miR-452-5p function in RB. MiR-452-5p expressions in RB were tested with quantitative real-time polymerase chain reaction (PCR). MiR-452-5p functions in RB were evaluated via Cell Counting Kit-8, 5-Ethynyl-2'-deoxyuridine assay, flow cytometry, Western blot, and Transwell. MiR-452-5p mechanism in RB was assessed using bioinformatics software Starbase and dual-luciferase reporter gene assay. Meanwhile, miR-452-5p function in RB in vivo was examined by constructing tumor xenografts in nude mice, immunohistochemistry, and Western blot assays. MiR-452-5p was overexpressed in RB tissues and cells, and miR-452-5p expression was positively correlated with RB clinicopathology including the Largest tumor base (mm) and Differentiation. Functionally, miR-452-5p knockdown restrained RB cell proliferation, invasion, epithelial-mesenchymal transition (EMT), and facilitated cell apoptosis. Mechanistically, suppressors of cytokine signaling (SOCS3) knockdown restored the inhibitory effects of miR-452-5p knockdown on RB cells. Meanwhile, in vivo studies further corroborated that miR-452-5p knockdown reduced RB tumor growth, EMT, and accelerated apoptosis in vivo. Also, miR-452-5p knockdown increased SOCS3 protein levels, and decreased phosphorylated Janus kinase 2/Janus kinase 2 (JAK2), phosphorylated signal transducer and activator of transcription 3/signal transducer and activator of transcription 3 (STAT3) in vivo. MiR-452-5p accelerated RB cell growth and invasion by SOCS3/JAK2/STAT3.

Diosmetin inhibits the growth and invasion of gastric cancer by interfering with M2 phenotype macrophage polarization

Overturning M2 phenotype macrophage polarization is a promising therapeutic strategy for gastric cancer (GC). Diosmetin (DIO) is a natural flavonoid with antitumor effect. The aim of this study was to investigate the effect of DIO on polarization of M2 phenotype macrophages in GC. THP-1 cells were induced to M2 phenotype macrophages and co-cultured with AGS cells. The effects of DIO were determined by flow cytometry, qRT-PCR, CCK-8, Transwell, and western blot. To explore the mechanisms, THP-1 cells were transfected with adenoviral vectors containing tumor necrosis factor receptor-associated factor 2 (TRAF2) or si-TRAF2. DIO (0, 5, 10, and 20 μM) restrained the M2 phenotype macrophage polarization. In addition, DIO (20 μM) reversed the increased viability and invasion of AGS cells induced by the co-culture of M2 macrophages. Mechanistically, TRAF2 knockdown inhibited the effect of M2 phenotype macrophages on AGS cells' growth and invasion. Furthermore, DIO (20 μM) was found to decrease TRAF2/NF-κB activity in GC cells. However, TRAF2 overexpressed reversed the inhibitory effect of DIO on the co-culture system. The in vivo study confirmed that DIO treatment (50 mg/kg) could repress the growth of GC. DIO treatment markedly reduced the expressions of Ki-67 and N-cadherin, and decreased the protein levels of TRAF2 and p-NF-κB/NF-κB. In conclusion, DIO inhibited the growth and invasion of GC cells by interfering with M2 phenotype macrophage polarization through repression of the TRAF2/NF-κB signaling pathway.

Synthesis of ursolic acid arylidene-hydrazide hybrid compounds and investigation of their cytotoxic and antimicrobial effects

In this study, 13 new hybrid compounds (7a-m) were synthesised starting from ursolic acid, and their cytotoxic activities were investigated on the BEAS-2B and A549 cell lines. In addition, the synthesised compounds were tested against Staphylococcus aureus, Escherichia coli, and Candida albicans to determine their anti-microbial properties. The hybrid compounds that exhibited the lowest cytotoxicity against the BEAS-2B were 7k, 7b, and 7g. The cytotoxicity of the compounds against A549 was evaluated, the IC50 value of 7k, 7b, and 7g are found as 0.15 µM, 0.31 µM, and 0.26 µM, respectively. The results showed that the selectivity of 7k was 7 times higher than doxorubicin against the A549 cells. According to the antimicrobial activity studies 7c is found as the most effective compound against S. aureus. Almost all compounds showed a similar inhibition potential against E. coli and C. albicans.

Cordycepin inhibited the retinoblastoma cell proliferation, migration, and invasion as well as lung metastasis via modulating c-Myc/cyclin D1 pathway

This study aims to investigate cordycepin's effects on the proliferation, migration, and invasion of retinoblastoma (RB) cells and its regulatory mechanism. In this study, it was found that cordycepin inhibited RB cell proliferation, migration, and invasion in vitro, and pulmonary metastasis in vivo. c-Myc was a downstream target of cordycepin, and cordycepin significantly suppressed c-Myc expression, and c-Myc overexpression markedly counteracted the impacts of cordycepin on RB cell proliferation, migration, and invasion. c-Myc was positively correlated with the cell cycle pathway. Cordycepin restrained cyclin D1 expression, and c-Myc overexpression rescued this effect. In conclusion, cordycepin targets the c-Myc/cyclin D1 pathway, thereby suppressing the malignant biological behaviors of RB cells.

SCD1 deficiency exacerbates osteoarthritis by inducing ferroptosis in chondrocytes

Background

Osteoarthritis (OA) is a severe joint disease that causes cartilage destruction and mobility loss. Abnormal fatty acid metabolism of chondrocytes plays a role in OA development. Stearoyl-CoA desaturase (SCD1) is a rate-limiting enzyme in the anabolism of unsaturated fatty acids. This study aimed to investigate the role of the SCD1 protein in the degenerative process of OA.

Methods

The GSE176199 gene expression profile dataset was analyzed by Gene Set Enrichment Analysis (GSEA). An animal model of OA was established using C57BL/6J wild-type (WT) (n=40) and SCD1 knockout (SCD1-KO) (n=20) mice. The histological scoring method of the Osteoarthritis Research Society International (OARSI) was used to quantify the degree of cartilage degeneration. The expression of SCD1 protein and relevant ferroptosis indicators were evaluated.

Results

The GSEA analysis showed that unsaturated fatty acid synthesis was inhibited in human OA chondrocytes. Meanwhile, the expression of SCD1 protein was significantly reduced in human OA articular cartilage. SCD1-KO mice exhibited early OA and accelerated cartilage loss after destabilization of medial meniscus (DMM)-induced OA. Furthermore, we found that the SCD1-PPARG axis regulates articular cartilage homeostasis via a mechanism involving the induction of ferroptosis-related gene expression in ATDC5 chondrocytes.

Conclusions

SCD1 deficiency exacerbates OA by inducing ferroptosis in chondrocytes.

Asiaticoside reverses M2 phenotype macrophage polarization-evoked osteosarcoma cell malignant behaviour by TRAF6/NF-κB inhibition

CONTEXT

M2 phenotype macrophage polarization is an attractive target for therapeutic intervention. Asiaticoside (ATS) has multiple pharmacological functions.

OBJECTIVE

This study investigates the effect of ATS on M2 phenotype macrophage polarization in osteosarcoma.

MATERIALS AND METHODS

The differentiation of human THP-1 monocytes into M0 phenotype macrophages was induced by 100 nM phorbol myristate acetate for 24 h, and treated with 20 ng/mL IL-4 and 20 ng/mL IL-13 for 48 h to obtain M2 phenotype macrophages. The function of ATS on the growth and invasion was investigated by cell counting kit-8, transwell, and western blot under the co-culture of M2 phenotype macrophages and osteosarcoma cells for 24 h. The mechanism of ATS on osteosarcoma was assessed using molecular experiments.

RESULTS

ATS reduced the THP-1 cell viability with an IC₅₀ of 128.67 μM. Also, ATS repressed the M2 phenotype macrophage polarization induced by IL-4/IL-13, and the effect was most notably at a 40 μM dose. ATS (40 μM) restrained the growth and invasion of osteosarcoma cells induced by M2 phenotype macrophages. In addition, ATS reduced the tumour necrosis factor receptor-associated factor 6 (TRAF6)/NF-κB activity in osteosarcoma cells and the TRAF6 knockdown reduced the growth and invasion of osteosarcoma cells induced by M2 phenotype macrophages. TRAF6 (2 μg/mL) attenuated the inhibitory effect of ATS on the growth and invasion of osteosarcoma cells caused by M2 phenotype macrophages. In vivo studies further confirmed ATS (2.5, 5, or 10 mg/kg) repressed osteosarcoma tumour growth.

DISCUSSION AND CONCLUSIONS

ATS reversed M2 phenotype macrophage polarization-evoked osteosarcoma cell malignant behaviour by reducing TRAF6/NF-κB activity, suggesting ATS might be a promising drug for the clinical treatment of osteosarcoma.

Therapeutic effect and mechanism of combination therapy with ursolic acid and insulin on diabetic nephropathy in a type I diabetic rat model

This work aims to investigate the therapeutic effect of ursolic acid (UA) plus insulin (In) on diabetic nephropathy (DN) in streptozotocin (STZ)-induced T1DM rats. The experimental groups and operational details are as follows: A total of thirty-two SD rats were divided into four groups: the DN model group (DN, n = 8), DN + In treatment group (DN + In, n = 8), DN + In + UA administration group (DN + In + UA, n = 8), and negative control group (control, n = 8). After 8 weeks, changes in renal function indices and pathological damage were assessed. Additionally, oxidative stress-, apoptosis-, and fibrosis-related proteins in kidney tissue were measured. Compared with the control group, the vehicle group showed higher levels of creatine, blood urea nitrogen, urinary protein, apoptosis, and lipid peroxidation; lower superoxide dismutase levels; more severe levels of pathological kidney damage and renal fibrosis; and a deepened degree of EMT and EndMT. Better outcomes were achieved with the combined treatment than with insulin-only treatment. The improvement of TGF-β1, phosphorylated p38 MAPK, FGFR1, SIRT3 and DPP-4 expression levels in renal tissues after combination therapy was greater than that after insulin-only treatment. This study shows that the combination of insulin and UA significantly improved the pathological changes in the renal tissue of T1DM rats, and the underlying mechanism may be related to improving apoptosis and oxidative stress by regulating p38 MAPK, SIRT3, DPP-4 and FGFR1 levels, thereby blocking TGF-β signaling pathway activation and inhibiting EMT and EndMT processes.