Identification and validation nucleolin as a target of curcumol in nasopharyngeal carcinoma cells

Applications of the Cellular Thermal Shift Assay to Drug Discovery in Natural Products: A Review

Natural products play a crucial role in drug discovery because of their structural diversity and biological activity. However, identifying their molecular targets remains a challenge. Traditional target identification approaches such as affinity-based protein profiling and activity-based protein profiling are limited by the need for chemical modification or reactive groups in natural products. The emergence of label-free techniques offers a powerful alternative for studying drug-target engagement in a physiological context. In particular, the cellular thermal shift assay (CETSA) exploits ligand-induced protein stabilization-a phenomenon where ligand binding enhances a protein's thermal stability by reducing conformational flexibility-to assess drug binding without requiring chemical modifications. CETSA's integration with advanced mass spectrometry and high-throughput platforms has dramatically expanded proteome coverage and sensitivity, enabling the simultaneous quantification of thousands of proteins and the identification of low-abundance targets in native cellular environments. This review highlights the application of key CETSA-based methods to target identification in natural products including Western blot-based CETSA, isothermal dose-response CETSA, mass spectrometry-based CETSA, and high-throughput CETSA. Case studies are presented that demonstrate their effectiveness in uncovering the mechanisms of action of different drugs. The current limitations of CETSA-based strategies are also explored, and future improvements to optimize their potential for drug discovery are discussed. Integrating CETSA with complementary approaches can enhance the target identification accuracy and efficiency for natural products and ultimately advance development of therapeutic applications.

Combating chemoresistance: Current approaches & nanocarrier mediated targeted delivery

Chemoresistance, a significant challenge in effective cancer treatment needs clear elucidation of the underlying molecular mechanism for the development of novel therapeutic strategies. Alterations in transporter pumps, oncogenes, tumour suppressor genes, mitochondrial function, DNA repair processes, autophagy, epithelial-mesenchymal transition (EMT), cancer stemness, epigenetic modifications, and exosome secretion lead to chemoresistance. Despite notable advancements in targeted cancer therapies employing both small molecules and macromolecules success rates remain suboptimal due to adverse effects like drug efflux, target mutation, increased mortality of normal cells, defective apoptosis, etc. This review proposes an advanced nanotechnological technique precisely targeting molecular determinants of chemoresistance which holds promise for enhancing cancer treatment efficacy. Further, the review explores various cancer hallmarks and pathways implicated in chemoresistance, current therapeutic modalities, and their limitations. It advocates the combination of nanoparticle-conjugated conventional drugs and natural compounds to specifically target molecular pathways that can potentially reverse or minimize chemoresistance incidences in cancer patients.

Novel Strategy of Antibody Affinity Maturation and Enhancement of Nucleolin-Mediated Antibody-Dependent Cellular Cytotoxicity Against Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a clinically aggressive subtype of breast cancer that remains an unmet medical need. Because TNBC cells do not express the most common markers of breast cancers, there is an active search for novel molecular targets in triple-negative tumors. Additionally, this subtype of breast cancer presents strong immunogenic characteristics which have been encouraging the development of immunotherapeutic approaches against the disease. In this context, nucleolin arises as a promising target for immunotherapy against TNBC. Our group has previously developed an anti-nucleolin VHH-Fc antibody capable of eliciting antibody-dependent cellular cytotoxicity (ADCC). Moreover, we constructed and characterized an antibody library, that was screened against nucleolin-overexpressing cells, originating an enriched anti-nucleolin antibody pool. In this work, a strategy to select individual clones from the pool was designed, combining NGS data with 3D modeling. Two antibodies demonstrated a significant 4.4- and 6.1-fold increase in binding to nucleolin-overexpressing and TNBC cells, and an improvement in affinity to the sub-micromolar range (0.19 µM and 83.69 nM). Additionally, an increment in 4.6- and 3.1-fold in ADCC activity against respective cell lines was observed for the M2 antibody clone. Herein, the affinity maturation strategy developed was validated and corroborated a positive, but not proportional, correlation between antibody binding, affinity, and ADCC.

Enhanced Detection of Curcumol in Biological Samples via Acetonitrile‐Anhydrous Sodium Sulfate Salt‐Assisted Liquid‐Liquid Microextraction Coupled With High‐Performance Liquid Chromatography

Curcumol, a significant bioactive molecule, requires accurate detection methods due to its extensive pharmacological properties. This study develops high‐performance liquid chromatography (HPLC) methods to detect curcumol and constructs sample pretreatment techniques using salt‐assisted liquid‐liquid microextraction (SALLME). The optimization process focuses on conditions for acetonitrile (ACN) anhydrous sodium sulfate‐assisted liquid‐liquid microextraction. By adding excess anhydrous sodium sulfate to an ACN aqueous solution, ACN precipitates, forming a saturated saline solution and resulting in a two‐phase system. Curcumol, being highly soluble in ACN, separates into and enriches within the ACN phase, achieving effective matrix separation. SALLME demonstrated an enrichment factor of up to 12.4 for curcumol. The extracted ACN is then injected into an HPLC instrument for quantitative detection and analysis. The method exhibited a good linear range (0.5–10.0 µg/mL) and a low detection limit (0.05 µg/mL). The results indicate that curcumol can be effectively separated from complex matrices using this technique. By optimizing salt concentration and temperature, the HPLC method for determining curcumol in biological samples was successfully established, achieving recoveries between 86.2% and 137.6% in spiked urine and blood samples. Furthermore, this method offers rapid, efficient, and environmentally friendly sample preparation, promising significant applications in pharmacological and clinical settings.

Multi-Omics Exploration of the Mechanism of Curcumol to Reduce Invasion and Metastasis of Nasopharyngeal Carcinoma by Inhibiting NCL/EBNA1-Mediated UBE2C Upregulation

Nasopharyngeal carcinoma (NPC) is closely linked to Epstein-Barr virus (EBV) infection. Curcumae Rhizoma, a traditional Chinese herb, has shown antitumor effects, primarily through its component curcumol (Cur), which has been shown to reduce NPC cell invasion and migration by targeting nucleolin (NCL) and Epstein-Barr Virus Nuclear Antigen 1 (EBNA1). We constructed an EBV-positive NPC cell model using C666-1 cells and performed transcriptomics studies after treatment with curcumol, which revealed a significant enrichment of ubiquitin-mediated proteolysis, the PI3K-AKT and mTOR signaling pathways, cell cycle and apoptosis involved in tumor invasion and migration. To investigate the importance of NCL and EBNA1 in curcumol-resistant EBV-positive NPC, we performed a multi-omics study using short hairpin NCL (shNCL) and shEBNA1 EBV-positive NPC cells, and the proteomics results showed enrichment in complement and coagulation cascades and ubiquitin-mediated proteolysis signaling pathways. Here, we focused on ubiquitin-conjugating enzyme E2C (UBE2C), which plays an important role in the ubiquitin-mediated proteolysis signaling pathway. In addition, metabolomics revealed that UBE2C is highly associated with 4-Aminobutanoic acid (GABA). In vitro studies further validated the function of the key targets, suggesting that UBE2C plays an important role in NCL and EBNA1-mediated curcumol resistance to nasopharyngeal carcinoma invasion and metastasis.

Curcumol: a review of its pharmacology, pharmacokinetics, drug delivery systems, structure-activity relationships, and potential applications

Curcumol (Cur), a guaiane-type sesquiterpenoid hemiketal, is an important and representative bioactive component extracted from the essential oil of the rhizomes of Curcumae rhizoma which is also known as "Ezhu" in traditional Chinese medicine. Recently, Cur has received considerable attention from the research community due to its favorable pharmacological activities, including anti-cancer, hepatoprotective, anti-inflammatory, anti-viral, anti-convulsant, and other activities, and has also exerted therapeutic effect on various cancers, liver diseases, inflammatory diseases, and infectious diseases. Pharmacokinetic studies have shown that Cur is rapidly distributed in almost all organs of rats after intragastric administration with high concentrations in the small intestine and colon. Several studies focusing on structure-activity relationship (SAR) of Cur have shown that some Cur derivatives, chemically modified at C-8 or C-14, exhibited more potent anti-cancer activity and lower toxicity than Cur itself. This review aims to comprehensively summarize the latest advances in the pharmacological and pharmacokinetic properties of Cur in the last decade with a focus on its anti-cancer and hepatoprotective potentials, as well as the research progress in drug delivery system and potential applications of Cur to date, to provide researchers with the latest information, to highlighted the limitations of relevant research at the current stage and the aspects that should be addressed in future research. Our results indicate that Cur and its derivatives could serve as potential novel agents for the treatment of a variety of diseases, particularly cancer and liver diseases.

Molecular interaction of quercetin and its derivatives against nucleolin in breast cancer: in-silico and in-vitro study

Nucleolin, a multifaceted RNA binding domain protein is overexpressed in various cancers leading to dysfunction of several cellular signaling pathways. Quercetin, a distinctive bioactive molecule, along with its derivatives have shown exclusive physio-chemical properties which makes them appealing choices for drug development, yet their role in targeted cancer therapy is limited. Here, the RBD domain structure of Nucleolin was modeled and stabilized by MD simulations for a period of 1000 ns. Molecular docking was performed to determine the binding capability of ligands with the target. To determine the stability of the ligand inside the binding pocket of the protein, MD simulation was performed for a period of 250 ns each for Quercetin-4'-o'-Glucoside, Quercetin_9 and Quercetin complexes. Further, in-vitro studies including cytotoxicity and RT-PCR assays were performed to validate quercetin against Nucleolin. Molecular docking and MD Simulation studies suggested a potential mechanism of interaction of Quercetin-4'-o'-Glucoside, Querectin_9 and Quercetin with Nucleolin with the binding free energy of -63.653, -58.86 and -46.9 kcal/mol, respectively. Moreover, Lys 348 and Glu379 were identified as important amino acids in ligand interaction located at the RRM2 motif of Nucleolin. In-vitro studies showed significant downregulation in Nucleolin expression by 15.18 and 2.51-fold at 48h and 72h respectively in MCF-7 cells with Quercetin (IC50 = 160 µM). Our findings suggested the potential role of specific RRM motifs in interaction with natural compounds targeting Nucleolin. This could be an effective strategy in the identification of potential molecules in targeting Nucleolin which can be further explored for developing targeted therapies for breast cancer.

The efficacy of natural products for the treatment of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a malignant tumor originating in the nasopharyngeal epithelium with a high incidence in southern China and parts of Southeast Asia. The current treatment methods are mainly radiotherapy and chemotherapy. However, they often have side effects and are not suitable for long-term exposure. Natural products have received more and more attention in cancer prevention and treatment because of their its high efficiency, low toxic side effects, and low toxicity. Natural products can serve as a viable alternative, and this study aimed to review the efficacy and mechanisms of natural products in the treatment of NPC by examining previous literature. Most natural products act by inhibiting cell proliferation, metastasis, inducing cell cycle arrest, and apoptosis. Although further research is needed to verify their effectiveness and safety, natural products can significantly improve the treatment of NPC.

Curcumol, a major terpenoid from Curcumae Rhizoma, attenuates human uterine leiomyoma cell development via the p38MAPK/NF-κB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Uterine fibroids (UFs) are the most common benign tumors in women of reproductive age. Curcumae Rhizoma, the main essential oil component of which is curcumol, is widely used for the treatment of phymatosis in China due to its antitumor, anti-inflammatory, antithrombin, anti-tissue fibrosis and anti-oxygen pharmacological activities, but its potential for the treatment of UFs has not been evaluated.

AIM OF THE STUDY

This study aimed to investigate the effects and mechanisms of curcumol intervention in human uterine leiomyoma cells (UMCs).

MATERIALS AND METHODS

Putative targets of curcumol intervention in UFs were identified using network pharmacology strategies. Molecular docking was performed to assess the binding affinity of curcumol to core targets. A concentration gradient of curcumol (0, 50, 100, 200, 300, 400 and 500 μM) or RU-486 (mifepristone, 0, 10, 20, 40, 50, and 100 μM) was applied to UMCs, and cell viability was detected by the CCK-8 assay. Cell apoptosis and cell cycle were examined by flow cytometry, and cell migration was assessed by a wound-healing assay. Additionally, the mRNA and protein expression levels of critical pathway components were evaluated by RT‒PCR and western blotting. Finally, the actions of curcumol on different tumor cell lines were summarized.

RESULTS

Network pharmacology predicted 62 genes with roles in the treatment of UFs with curcumol, and MAPK14 (p38MAPK) displayed a higher interaction degree. GO enrichment and KEGG analyses revealed that the core genes were abundantly enriched in the MAPK signaling pathway. The molecular binding of curcumol to core targets was relatively stable. In UMCs, 200, 300 and 400 μM curcumol treatment for 24 h decreased cell viability compared with that in the control group, and the greatest effect was detected at 48 h and maintained until 72 h. Curcumol arrested cells in the G0/G1 phase and subsequently suppressed mitosis, promoted early apoptosis and reduced the degree of wound healing in a concentration-dependent manner in UMCs. Furthermore, 200 μM curcumol decreased the mRNA and protein expression of p38MAPK, the mRNA expression of NF-κB, and the protein expression of Ki-67 and increased the mRNA and protein expression of Caspase 9. Curcumol (300 and 400 μM) decreased the mRNA and protein expression of p38MAPK, NF-κB, and Ki-67 and increased the protein expression of Caspase 9 in UMCs. Curcumol was demonstrated to treat tumor cell lines, including breast cancer, ovarian cancer, lung cancer, gastric cancer, liver cancer and nasopharyngeal carcinoma, but its effects on benign tumors have not yet been reported.

CONCLUSION

Curcumol suppresses cell proliferation and cell migration while arresting the cell cycle in the G0/G1 phase and inducing cell apoptosis in UMCs via a mechanism related to p38MAPK/NF-κB pathway regulation. Curcumol may be a potential therapeutic and preventive agent in the treatment of benign tumors such as UFs.

CETSA and thermal proteome profiling strategies for target identification and drug discovery of natural products

BACKGROUND

Monitoring target engagement at various stages of drug development is essential for natural product (NP)-based drug discovery and development. The cellular thermal shift assay (CETSA) developed in 2013 is a novel, broadly applicable, label-free biophysical assay based on the principle of ligand-induced thermal stabilization of target proteins, which enables direct assessment of drug-target engagement in physiologically relevant contexts, including intact cells, cell lysates and tissues. This review aims to provide an overview of the work principles of CETSA and its derivative strategies and their recent progress in protein target validation, target identification and drug lead discovery of NPs.

METHODS

A literature-based survey was conducted using the Web of Science and PubMed databases. The required information was reviewed and discussed to highlight the important role of CETSA-derived strategies in NP studies.

RESULTS

After nearly ten years of upgrading and evolution, CETSA has been mainly developed into three formats: classic Western blotting (WB)-CETSA for target validation, thermal proteome profiling (TPP, also known as MS-CETSA) for unbiased proteome-wide target identification, and high-throughput (HT)-CETSA for drug hit discovery and lead optimization. Importantly, the application possibilities of a variety of TPP approaches for the target discovery of bioactive NPs are highlighted and discussed, including TPP-temperature range (TPP-TR), TPP-compound concentration range (TPP-CCR), two-dimensional TPP (2D-TPP), cell surface-TPP (CS-TPP), simplified TPP (STPP), thermal stability shift-based fluorescence difference in 2D gel electrophoresis (TS-FITGE) and precipitate supported TPP (PSTPP). In addition, the key advantages, limitations and future outlook of CETSA strategies for NP studies are discussed.

CONCLUSION

The accumulation of CETSA-based data can significantly accelerate the elucidation of the mechanism of action and drug lead discovery of NPs, and provide strong evidence for NP treatment against certain diseases. The CETSA strategy will certainly bring a great return far beyond the initial investment and open up more possibilities for future NP-based drug research and development.

RNA-binding domain 2 of nucleolin is important for the autophagy induction of curcumol in nasopharyngeal carcinoma cells

BACKGROUND & AIMS

Excessive autophagy induces cell death and is regarded as the treatment of cancer therapy. We have confirmed that the anti-cancer mechanism of curcumol is related to autophagy induction. As the main target protein of curcumol, RNA binding protein nucleolin (NCL) interacted with many tumor promoters accelerating tumor progression. However, the role of NCL in cancer autophagy and in curcumol's anti-tumor effects haven't elucidated. The purpose of the study is to identify the role of NCL in nasopharyngeal carcinoma autophagy and reveal the immanent mechanisms of NCL played in cell autophagy.

METHODS & RESULTS

In the current study, we have found that NCL was markedly upregulated in nasopharyngeal carcinoma (NPC) cells. NCL overexpression effectively attenuated the level of autophagy in NPC cells, and NCL silence or curcumol treatment obviously aggravated the autophagy of NPC cells. Moreover, the attenuation of NCL by curcumol lead a significant suppression on PI3K/AKT/mTOR signaling pathway in NPC cells. Mechanistically, NCL was found to be directly interact with AKT and accelerate AKT phosphorylation, which caused the activation of the PI3K/AKT/mTOR pathway. Meanwhile, the RNA Binding Domain (RBD) 2 of NCL interacts with Akt, which was also influenced by curcumol. Notably, the RBDs of NCL delivered AKT expression was related with cell autophagy in the NPC.

CONCLUSION

The results demonstrated that NCL regulated cell autophagy was related with interaction of NCL and Akt in NPC cells. The expression of NCL play an important role in autophagy induction and further found that was associated with its effect on NCL RNA-binding domain 2. This study may provide a new perspective on the target protein studies for natural medicines and confirm the effect of curcumol not only regulating the expression of its target protein, but also influencing the function domain of its target protein.

Curcumol inhibits breast cancer growth via NCL/ERα36 and the PI3K/AKT pathway

Background: Breast cancer (BC) is the most common malignancy worldwide. ERα36 (ERα66 variant) is expressed in many breast cancer cells, especially highly expressed in tamoxifen (TAM)-resistant cell lines and triple-negative breast cancer, and our previous work revealed that nucleolin (NCL) is a protein target of curcumol. This study is aimed at investigating the effect and mechanism of curcumol on ERα36 positive breast cancer cells, and the relationship between curcumol's target protein NCL and ERα36. Study design: Application of in vivo and in vitro studies to reveal the mechanism of curcumol in inhibiting BC growth and the relationship between curcumol's target protein NCL and ERα36. Methods: The anti-tumor effect of curcumol was quantified via an MTT assay, colony formation and cycle arrest, respectively. The expressions of ERα36, NCL and the proteins involved in PI3K/AKT signaling were evaluated by western blotting. The interaction between two proteins was detected using co-immunoprecipitation (Co-IP) and an immunofluorescence assay. A mouse xenograft model was established to verify the role of ERα36 in breast cancer cells and curcumol's effect on ERα36 positive cancer cells. Results: Curcumol inhibited the cell growth, caused cell cycle arrest, decreased cell cycle related proteins and inactivated the PI3K/AKT pathway in ERα36 positive breast cancer cells. There is a positive correlation between NCL and ERα36 in breast cancer cells. In addition, ERα36 bound to NCL; the two proteins were distributed in the nucleus, cytoplasm and plasma membrane, where their expression was obviously decreased by curcumol. Moreover, NCL silenced by NCL siRNA blocked the cell cycle progress and inhibited the activation of PI3K/AKT in MDA-MB-231 cells, while overexpressed ERα36 increased the expression of NCL, promoted the cell cycle progress and enhanced the activity of PI3K/AKT in MCF-7 cells. NCL knockdown or ERα36 overexpression attenuated the effect of curcumol on breast cancer cells. Conclusion: Curcumol reduced the proliferation of breast cancer cells by targeting NCL/ERα36 and inactivating the PI3K/AKT pathway.

Pre-clinical and clinical importance of miR-21 in human cancers: Tumorigenesis, therapy response, delivery approaches and targeting agents

The field of non-coding RNA (ncRNA) has made significant progress in understanding the pathogenesis of diseases and has broadened our knowledge towards their targeting, especially in cancer therapy. ncRNAs are a large family of RNAs with microRNAs (miRNAs) being one kind of endogenous RNA which lack encoded proteins. By now, miRNAs have been well-coined in pathogenesis and development of cancer. The current review focuses on the role of miR-21 in cancers and its association with tumor progression. miR-21 has both oncogenic and onco-suppressor functions and most of the experiments are in agreement with the tumor-promoting function of this miRNA. miR-21 primarily decreases PTEN expression to induce PI3K/Akt signaling in cancer progression. Overexpression of miR-21 inhibits apoptosis and is vital for inducing pro-survival autophagy. miR-21 is vital for metabolic reprogramming and can induce glycolysis to enhance tumor progression. miR-21 stimulates EMT mechanisms and increases expression of MMP-2 and MMP-9 thereby elevating tumor metastasis. miR-21 is a target of anti-cancer agents such as curcumin and curcumol and its down-regulation impairs tumor progression. Upregulation of miR-21 results in cancer resistance to chemotherapy and radiotherapy. Increasing evidence has revealed the role of miR-21 as a biomarker as it is present in both the serum and exosomes making them beneficial biomarkers for non-invasive diagnosis of cancer.

Impairment of Nucleolin Activity and Phosphorylation by a Trachylobane Diterpene from Psiadia punctulata in Cancer Cells

Human nucleolin (hNcl) is a multifunctional protein involved in the progression of various cancers and plays a key role in other pathologies. Therefore, there is still unsatisfied demand for hNcl modulators. Recently, we demonstrated that the plant ent-kaurane diterpene oridonin inhibits hNcl but, unfortunately, this compound is quite toxic for healthy cells. Trachylobane diterpene 6,19-dihydroxy-ent-trachiloban-17-oic acid (compound 12) extracted from Psiadia punctulata (DC.) Vatke (Asteraceae) emerged as a ligand of hNcl from a cellular thermal shift assay (CETSA)-based screening of a small library of diterpenes. Effective interaction between this compound and the protein was demonstrated to occur both in vitro and inside two different types of cancer cells. Based on the experimental and computational data, a model of the hNcl/compound 12 complex was built. Because of this binding, hNcl mRNA chaperone activity was significantly reduced, and the level of phosphorylation of the protein was affected. At the biological level, cancer cell incubation with compound 12 produced a cell cycle block in the subG0/G1 phase and induced early apoptosis, whereas no cytotoxicity towards healthy cells was observed. Overall, these results suggested that 6,19-dihydroxy-ent-trachiloban-17-oic could represent a selective antitumoral agent and a promising lead for designing innovative hNcl inhibitors also usable for therapeutic purposes.

Curcumol Synergizes with Cisplatin in Osteosarcoma by Inhibiting M2-like Polarization of Tumor-Associated Macrophages

Osteosarcoma is the most prevalent bone cancer, and chemotherapy is still an indispensable treatment in its clinical practice. Cisplatin (CDDP) has become the most commonly used agent for osteosarcoma, although the outcomes of CDDP chemotherapy remain unsatisfactory because of frequent resistance. Here, we report on a promising combination therapy where curcumol, a bioactive sesquiterpenoid, enhanced CDDP-induced apoptosis to eradicate osteosarcoma cells, and revealed that M2-like macrophages might be the underlying associated mechanisms. First, we observed that curcumol enhanced the CDDP-mediated inhibition of cell proliferation and augmented the apoptosis in osteosarcoma cell lines. Curcumol contributed to preventing the migration of osteosarcoma cells when combined with CDDP. Moreover, this drug combination showed more potent tumor-growth suppression in the orthotopic transplantation of osteosarcoma K7M2 WT cells. We then estimated chemotherapy-associated drug-resistant genes, including ABCB1, ABCC1 and ABCG2, and found that curcumol significantly reversed the mRNA levels of CDDP-induced ABCB1, ABCC1 and ABCG2 genes in the tumor tissue. Moreover, M2-like macrophages were enriched in osteosarcoma tissues, and were largely decreased after curcumol and CDDP treatment. Taken together, these findings suggest that curcumol inhibits the polarization of M2-like macrophages and could be a promising combination strategy to synergize with CDDP in the osteosarcoma.

Design, synthesis, and anticancer activity evaluation of curcumol derivatives

A new series of C-14 curcumol derivatives as potent anticancer agents were designed and synthesized by click reaction, whose structures were confirmed by ¹H NMR,¹³C NMR, and HRMS analysis. All the synthesized compounds were evaluated for in vitro antitumor activity against colorectal cancer cell lines SW620 and HCT116. Most of them exhibited higher inhibitory activity than curcumol. Especially, compound 3j shows good inhibitory activity against SW620 with IC₅₀ value of 8.10 ± 0.13 μM. The structure-activity relationships (SARs) of these derivatives were discussed. In addition, flow cytometry revealed that compound 3j induced SW620 cells apoptosis by facilitating apoptosis-related proteins expressions. Our findings suggested that fluorine functional group on phenyl ring tended to increase the anticancer activity.

Currently Available Strategies for Target Identification of Bioactive Natural Products

In recent years, biologically active natural products have gradually become important agents in the field of drug research and development because of their wide availability and variety. However, the target sites of many natural products are yet to be identified, which is a setback in the pharmaceutical industry and has seriously hindered the translation of research findings of these natural products as viable candidates for new drug exploitation. This review systematically describes the commonly used strategies for target identification via the application of probe and non-probe approaches. The merits and demerits of each method were summarized using recent examples, with the goal of comparing currently available methods and selecting the optimum techniques for identifying the targets of bioactive natural products.

Curcumol inhibits EBV-positive Nasopharyngeal carcinoma migration and invasion by targeting nucleolin

Metastasis is a major cause of recurrence and death in patients with EBV-positive Nasopharyngeal carcinoma (NPC). Previous reports documented that curcumol has both anti-cancer and anti-viral effects, but there is little literature systematically addressing the mechanism of curcumol in EBV-positive tumors. Previously we found that nucelolin (NCL) is a target protein of curcumol in CNE2 cells, an EBV-negative NPC, and in this experiment, we reported a critical role for NCL in promoting migration and invasion of C666-1 cells, an EBV-positive NPC, and found that the expression of NCL determined the level of curcumol's efficacy. Mechanistically, NCL interacted with Epstein-Barr Virus Nuclear Antigen 1 (EBNA1) to activate VEGFA/VEGFR1/PI3K/AKT signaling pathway, which in turn promoted NPC cell invasion and metastasis. Moreover, further study showed that the differential expression of NCL and curcumol intervention only had a regulatory effect on the nuclear accumulation of VEGFR1, which strengthened the anti-cancer effect of curcumol mediated through NCL. Our findings indicated that curcumol exerted anti EBV-positive NPC invasion and metastasis by downregulating EBNA1 and inhibiting VEGFA/VEGFR1/PI3K/AKT signaling by targeting NCL, which provides a novel pharmacological basis for curcumol's clinical use in treating patients with EBV-positive NPC.

Curcumol increases the sensitivity of colon cancer to 5-FU by regulating Wnt/β-catenin signaling

Background

5-fluorouracil (5-FU) resistance is the leading cause of treatment failure in colon cancer. Combination therapy is an effective strategy to inhibit cancer cells and prevent drug resistance. Therefore, we studied the antitumor effect of curcumol alone or combined with 5-FU on human colon cancer drug-resistant cells.

Methods

The 5-FU resistant HCT116 cell line (HCT116/5-FU) was established by repeated exposure to gradually increasing concentrations of 5-FU; Cell viability was measured by cell counting kit-8 (CCK-8); apoptosis rate of HCT116 cells was detected using Annexin V-fluorescein isothiocyanate (FITC) assay kit; cell proliferation and invasion were detected using colony formation assays, wound healing assay and transwell invasion assays; activity of transplanted tumor in vivo in specific pathogen free (SPF) BALB/c nude mice (6 weeks old, male) was monitored by bioluminescence imaging, immunohistochemistry and western blot analysis.

Results

Our study showed the potent antitumor effect of curcumol by induction of apoptosis, inhibition of proliferation, invasion, migration, and improvement of the therapeutic efficacy of 5-FU toward human colon cancer HCT116 cells. From our results, curcumol could chemosensitize 5-FU-resistant HCT116 cells. The combination of curcumol and 5-FU exerted a synergistic inhibitory effect on the induction of apoptosis. Also, this combination inhibited the proliferation, invasion, and migration of both chemo-resistant and sensitive cells. Curcumol treatment decreased multidrug resistance-associated protein 2 (MRP-2), P-glycoprotein (P-gp), survivin, and β-catenin expression, which correlated with multidrug resistance (MDR) and the target genes of Wnt/β-catenin. It significantly increased the p-β-catenin level and Bad/Bcl-2 ratio in HCT116/5-FU cells compared with 5-FU treatment. In vivo, curcumol significantly inhibited the growth of transplanted tumors and the expression of Ki-67, proliferating cell nuclear antigen (PCNA), and vascular endothelial growth factor (VEGF) in colon cancer cells.

Conclusions

Curcumol as a potential chemotherapeutic agent combined with 5-FU can overcome colon cancer resistance.

Terpenoids from Curcumae Rhizoma: Their anticancer effects and clinical uses on combination and versus drug therapies

Cancer is a fatal disease with high mortality and low survival rate worldwide. At present, there is still no known cure for most cancers. Traditional Chinese medicine (TCM) represents a noteworthy reservoir for anticancer agents in drug discovery and development. Curcumae Rhizoma (called Ezhu in Chinese) is widely prescribed in TCM for anticancer therapy owing to its broad-spectrum antineoplastic activities. Especially, the terpenoids isolated from the essential oil of Curcumae Rhizoma form an integral part of cancer research and are well established as a potential anticancer agent. For example, β-elemene has been developed into a new drug for the treatment of solid tumors in China, and is currently undergoing clinical trials in the United States. The review aims to systematically summarize the recent advances on the anticancer effects and related molecular mechanisms of Curcumae Rhizoma, and its terpenoids (β-elemene, Furanodiene, Furanodienone, Germacrone, Curcumol, Curdione). In addition, we evaluated and compared the anticancer efficacy and clinical use of the terpenoids with combination therapies and traditional therapies. Therefore, this review provides sufficient evidence for the anticancer therapeutic potential of Curcumae Rhizoma and its terpenoids, and will contribute to the development of potential anticancer drugs.

RNA packaging into extracellular vesicles: An orchestra of RNA-binding proteins?

Extracellular vesicles (EVs) are heterogeneous membranous particles released from the cells through different biogenetic and secretory mechanisms. We now conceive EVs as shuttles mediating cellular communication, carrying a variety of molecules resulting from intracellular homeostatic mechanisms. The RNA is a widely detected cargo and, impressively, a recognized functional intermediate that elects EVs as modulators of cancer cell phenotypes, determinants of disease spreading, cell surrogates in regenerative medicine, and a source for non-invasive molecular diagnostics. The mechanistic elucidation of the intracellular events responsible for the engagement of RNA into EVs will significantly improve the comprehension and possibly the prediction of EV "quality" in association with cell physiology. Interestingly, the application of multidisciplinary approaches, including biochemical as well as cell-based and computational strategies, is increasingly revealing an active RNA-packaging process implicating RNA-binding proteins (RBPs) in the sorting of coding and non-coding RNAs. In this review, we provide a comprehensive view of RBPs recently emerging as part of the EV biology, considering the scenarios where: (i) individual RBPs were detected in EVs along with their RNA substrates, (ii) RBPs were detected in EVs with inferred RNA targets, and (iii) EV-transcripts were found to harbour sequence motifs mirroring the activity of RBPs. Proteins so far identified are members of the hnRNP family (hnRNPA2B1, hnRNPC1, hnRNPG, hnRNPH1, hnRNPK, and hnRNPQ), as well as YBX1, HuR, AGO2, IGF2BP1, MEX3C, ANXA2, ALIX, NCL, FUS, TDP-43, MVP, LIN28, SRP9/14, QKI, and TERT. We describe the RBPs based on protein domain features, current knowledge on the association with human diseases, recognition of RNA consensus motifs, and the need to clarify the functional significance in different cellular contexts. We also summarize data on previously identified RBP inhibitor small molecules that could also be introduced in EV research as potential modulators of vesicular RNA sorting.

Curcumol improves cisplatin sensitivity of human gastric cancer cells through inhibiting PI3K/AKT pathway

BACKGROUND

Curcumol was presented to unleash antitumor effects in a variety of cancers, including gastric cancer. However, the relevance between curcumol and cisplatin resistance in gastric cancer still remains unclear. Therefore, the current research was performed to survey the role of curcumol in cisplatin sensitivity in gastric cancer.

METHODS

First, BGC-823 and BGC-823/DDP cells were incubated with cisplatin for 48 hr and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) analysis was applied to determine the inhibition rate of cell proliferation and the half-maximal inhibitory concentration (IC50 ) of cisplatin. In addition, BGC-823 and BGC-823/DDP cells were treated with curcumol for 48 hr followed with detection of cell viability and apoptosis using MTT and flow cytometry assay, respectively. Moreover, MTT analysis was applied to test the effects of curcumol on cisplatin sensitivity in gastric cancer cells. Lastly, Western blot assay and qRT-PCR analysis were utilized to check the functions of curcumol on PI3K/AKT pathway-related markers.

RESULTS

We found that BGC-823/DDP cells exhibited stronger resistance to cisplatin compared with BGC-823 cells. Furthermore, curcumol evidently reduced cell proliferation and facilitated cell apoptosis in BGC-823/DDP and BGC-823 cells. Moreover, results from MTT assay demonstrated that curcumol notably promoted the suppression effect of cisplatin and decreased the IC50 of cisplatin in BGC-823/DDP and BGC-823 cells. It was also presented that curcumol suppressed the PI3K/AKT pathway dose-dependently in BGC-823/DDP and BGC-823 cells.

CONCLUSION

The findings in the current research demonstrated that curcumol could promote the sensitivity of gastric cancer cells to cisplatin-based chemotherapies via inhibiting the phosphatidylinositol 3-kinase (PI3K)/Protein Kinase B (AKT) pathway.

Target identification and validation of natural products with label-free methodology: A critical review from 2005 to 2020

Natural products (NPs) have been an important source of therapeutic drugs in clinic use and contributed many chemical probes for research. The usefulness of NPs is however often marred by the incomplete understanding of their direct cellular targets. A number of experimental methods for drug target identification have been developed over the years. One class of methods, termed "label-free" methodology, exploits the energetic and biophysical features accompanying the association of macromolecules with drugs and other compounds in their native forms. Herein we review the working principles, assay implementations, and key applications of the most important approaches, and also give examples where they have been applied to NPs. We also assess the key advantages and limitations of each method. Furthermore, we address when and how the label-free methodology can be particularly useful considering some of the unique features of NP chemistry and bioactivation.

Study on the Drug Targets and Molecular Mechanisms of Rhizoma Curcumae in the Treatment of Nasopharyngeal Carcinoma Based on Network Pharmacology

Aim

To analyse the target of Rhizoma Curcumae in nasopharyngeal carcinoma by using network pharmacological techniques and to explore the associated molecular mechanism.

Methods

The targets of nasopharyngeal carcinoma were retrieved from the GeneCards database. At the same time, the drug therapeutic targets of Rhizoma Curcumae were obtained from the TCMSP and SymMap databases. The data were imported into the STRING database and Cytoscape 3.7.1 to construct a network of “Chinese medicine component-target-disease” interactions; then, the intersection was screened as the core Rhizoma Curcumae antinasopharyngeal cancer targets. Through GO target function and KEGG pathway enrichment analyses of the core targets, we predicted the biological processes and key signalling pathways involved in the Rhizoma Curcumae treatment of nasopharyngeal carcinoma.

Results

Twenty-five core targets of Rhizoma Curcumae in nasopharyngeal carcinoma were mined: TP53, BCL2 ICAM1 RXRA, TLR3 and TLR9, TNF, PTGS2, IL-6, CTSD, MMP2, MMP9, MMP14, TIMP2, ABCC1, ABCB1, ABCG2, and so on. The results of visual analysis showed that the Rhizoma Curcumae treatment of nasopharyngeal carcinoma mainly involves leukocyte adhesion to vascular endothelial cells, positive regulation of NF-κB import into the nucleus, regulation of the reactive oxygen species biosynthetic and metabolic process, regulation of the chemokine biosynthetic and metabolic process, various cancer-related signalling pathways, and a variety of cytokine signal transduction pathways, such as the NF-κB, TLR, IL-17, and TNF signalling pathways.

Conclusion

The core targets predicted by our research can be used as molecular markers for the treatment and prediction of nasopharyngeal carcinoma. The mechanism of Rhizoma Curcumae treatment in NPC may be related to immune regulatory pathways, the inhibition of cancer cell proliferation, metastasis, and angiogenesis, as well as the regulation of tumour microenvironment. Combined with the prediction of its associated mechanism of action, the core targets can provide targeted reference value for subsequent drug development related to Curcuma.

Therapeutic Effects of Curcumol in Several Diseases; An Overview

Curcumae Rhizoma, also known as Ezhu is a traditional Chinese medicine that has been used for many centuries against several diseases. The rhizome of the plant is composed of curcuminoids (curcumin, demethoxycurcumin, and bisdemethoxycurcumin), and essential volatile oils including curcumol, curdione, and germacrone. While curcuminoids have been extensively studied for their antimicrobial, antioxidant, anti-inflammatory and anticancer properties, the therapeutic efficacy of curcumol is still emerging. Recent studies have shown anticancer properties of curcumol against multiple solid tumors such as breast, colorectal, head and neck, and lung adenocarcinomas. The underlying anti-tumor mechanisms revealed inhibition of several signaling pathways (NF-κB, MAPK, PI-3K/AKT, and GSK-3β) associated with cell proliferation, survival, anti-apoptosis, invasion and metastasis. Besides curcumol, extracts from the Curcumae Rhizoma roots possess many other terpenoids such as β-elemene, δ-elemene, germacrone, furanodiene and furanodienone with known anticancer properties. In this review, we comprehensively focused on the composition of Curcumae Rhizoma essential oils, their structure, isolation and therapeutic uses of curcumol to aid in the improvement and development of novel drugs with minimal cytotoxicity, enhanced efficacy, and less cost.

Cinnamaldehyde Enhances Antimelanoma Activity through Covalently Binding ENO1 and Exhibits a Promoting Effect with Dacarbazine

At present, melanoma is a common malignant tumor with the highest mortality rate of all types of skin cancer. Although the first option for treating melanoma is with chemicals, the effects are unsatisfactory and include poor medication response and high resistance. Therefore, developing new medicines or a novel combination approach would be a significant breakthrough. Here, we present cinnamaldehyde (CA) as a potential candidate, which exerted an antitumor effect in melanoma cell lines. Chemical biology methods of target fishing, molecular imaging, and live cell tracing by an alkynyl-CA probe revealed that the α-enolase (ENO1) protein was the target of CA. The covalent binding of CA with ENO1 changed the stability of the ENO1 protein and affected the glycolytic activity. Furthermore, our results demonstrated that dacarbazine (DTIC) showed a high promoting effect with CA for antimelanoma both in vivo and in vitro. The combination improved the DTIC cell cycle arrest in the S phase and markedly impacted melanoma growth. As a covalent inhibitor of ENO1, CA combined with DTIC may be beneficial in patients with drug resistance in antimelanoma therapy.

Traditional Chinese Medicine in Oncotherapy: The Research Status

In China, Traditional Chinese Medicine (TCM) plays a vital role in the comprehensive treatment of cancer. As an auxiliary and supplement of major treatment modalities for cancer such as surgery, chemotherapy, and radiotherapy, both clinical observations and biomolecular research have confirmed the therapeutic efficacy of TCM in cancer.

Biologically active metabolite(s) from haemolymph of red-headed centipede Scolopendra subspinipes possess broad spectrum antibacterial activity

The discovery of novel antimicrobials from animal species under pollution is an area untapped. Chinese red-headed centipede is one of the hardiest arthropod species commonly known for its therapeutic value in traditional Chinese medicine. Here we determined the antibacterial activity of haemolymph and tissue extracts of red-headed centipede, Scolopendra subspinipes against a panel of Gram-positive and Gram-negative bacteria. Lysates exhibited potent antibacterial activities against a broad range of bacteria tested. Chemical characterization of biologically active molecules was determined via liquid chromatography mass spectrometric analysis. From crude haemolymph extract, 12 compounds were identified including: (1) L-Homotyrosine, (2) 8-Acetoxy-4-acoren-3-one, (3) N-Undecylbenzenesulfonic acid, (4) 2-Dodecylbenzenesulfonic acid, (5) 3H-1,2-Dithiole-3-thione, (6) Acetylenedicarboxylate, (7) Albuterol, (8) Tetradecylamine, (9) Curcumenol, (10) 3-Butylidene-7-hydroxyphthalide, (11) Oleoyl Ethanolamide and (12) Docosanedioic acid. Antimicrobial activities of the identified compounds were reported against Gram-positive and Gram-negative bacteria, fungi, viruses and parasites, that possibly explain centipede's survival in harsh and polluted environments. Further research in characterization, molecular mechanism of action and in vivo testing of active molecules is needed for the development of novel antibacterials.

Curcumol: From Plant Roots to Cancer Roots

Natural products, an infinite treasure of bioactive scaffolds, have provided an excellent reservoir for the discovery of drugs since millennium. These naturally occurring, biologically active and therapeutically effective chemical entities have emerged as novel paradigm for the prevention of various diseases. This review aims to give an update on the sources as well as pharmacological profile of curcumol, a pharmacologically active sesquiterpenoid, which is an imperative bioactive constituent of several plants mainly from genus Curcuma. Curcumol has potential to fight against cancer, oxidative stress, neurodegeneration, microbial infections, and inflammation. Curcumol has been documented as potent inducer of apoptosis in numerous cancer cells via targeting key signaling pathways as MAPK/ERK, PI3K/Akt and NF-κB which are generally deregulated in several cancers. The reported data reveals multitarget activity of curcumol in cancer treatment suggesting its importance as anticancer drug in future. It is speculated that curcumol may provide an excellent opportunity for the cure of cancer but further investigations on mechanism of its action and preclinical trials are still mandatory to further validate the potential of this natural cancer killer in anticancer therapies.

Curcumol inhibits colorectal cancer proliferation by targeting miR-21 and modulated PTEN/PI3K/Akt pathways

AIMS

The purpose of this study was to demonstrate how curcumol affected the expression of miR-21 and whether its effects on miR-21 was associated with the activation of PTEN/PI3K/Akt pathways in CRC cells.

MAIN METHODS

MTT and xenograft assay were used to examine how curcumol inhibits colorectal cancer (CRC) cells' growth. Q-PCR and western blot analysis were employed to test the role of miR-21 in the inhibition of curcumol on proliferation and PTEN/PI3K/Akt pathways of CRC cells.

KEY FINDINGS

We found that curcumol effectively inhibited CRC cells from proliferating via the PTEN/PI3K/Akt pathways and reduced expression of miR-21 both in vitro and in vivo. miR-21 mimics were found to decrease the protein level of PTEN and increase the expression of PI3K, phospho-Akt (p-Akt) and NF-κB, while miR-21 sponge (miR-21-SP) enhanced the expression of PTEN and reduced the activity of PI3K, Akt and NF-κB. Furthermore, miR-21-SP strengthened the role of curcumol in up-regulating PTEN and inhibiting PI3K/Akt pathways, but miR-21 reversed the effect of curcumol on the PTEN/PI3K/Akt pathways.

SIGNIFICANCE

Our research demonstrated that curcumol reduced the proliferation of CRC cells through PTEN/PI3K/Akt by targeting miR-21 and miR-21 could be a target molecule of curcumol for CRC treatment.

Curcumol induces RIPK1/RIPK3 complex-dependent necroptosis via JNK1/2-ROS signaling in hepatic stellate cells

It is generally recognized that hepatic fibrogenesis is an end result of increased extracellular matrix (ECM) production from the activation and proliferation of hepatic stellate cells (HSCs). An in-depth understanding of the mechanisms of HSC necroptosis might provide a new therapeutic strategy for prevention and treatment of hepatic fibrosis. In this study, we attempted to investigate the effect of curcumol on necroptosis in HSCs, and further to explore the molecular mechanisms. We found that curcumol ameliorated the carbon tetrachloride (CCl₄)-induced mice liver fibrosis and suppressed HSC proliferation and activation, which was associated with regulating HSC necroptosis through increasing the phosphorylation of receptor-interacting protein kinase 1 (RIPK1), receptor-interacting protein kinase 3 (RIPK3). Moreover, curcumol promoted the migration of RIPK1 and RIPK3 into necrosome in HSCs. RIPK3 depletion impaired the anti-fibrotic effect of curcumol. Importantly, we showed that curcumol-induced RIPK3 up-regulation significantly increased mitochondrial reactive oxygen species (ROS) production and mitochondrial depolarization. ROS scavenger, N-acetyl-L-cysteine (NAC) impaired RIPK3-mediated necroptosis. In addition, our study also identified that the activation of c-Jun N-terminal kinase1/2 (JNK1/2) was regulated by RIPK3, which mediated curcumol-induced ROS production. Down-regulation of RIPK3 expression, using siRIPK3, markedly abrogated JNK1/2 expression. The use of specific JNK1/2 inhibitor (SP600125) resulted in the suppression of curcumol-induced ROS production and mitochondrial depolarization, which in turn, contributed to the inhibition of curcumol-triggered necroptosis. In summary, our study results reveal the molecular mechanism of curcumol-induced HSC necroptosis, and suggest a potential clinical use of curcumol-targeted RIPK1/RIPK3 complex-dependent necroptosis via JNK1/2-ROS signaling for the treatment of hepatic fibrosis.

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Curcumol exerted anti-hepatic fibrogenesis effects in CCl₄-treated mice.

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Curcumol inhibited the activation of hepatic stellate cell in vitro.

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Curcumol promoted the generation of RIPK1/RIPK3-complex to induce hepatic stellate cell necroptosis.

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Curcumol modulated RIPK3/JNK/ROS signaling axis.

The nucleolus, an ally, and an enemy of cancer cells

The rates of ribosome production by a nucleolus and of protein biosynthesis by ribosomes are tightly correlated with the rate of cell growth and proliferation. All these processes must be matched and appropriately regulated to provide optimal cell functioning. Deregulation of certain factors, including oncogenes, controlling these processes, especially ribosome biosynthesis, can lead to cell transformation. Cancer cells are characterized by intense ribosome biosynthesis which is advantageous for their growth and proliferation. On the other hand, this feature can be engaged as an anticancer strategy. Numerous nucleolar factors such as nucleolar and ribosomal proteins as well as different RNAs, in addition to their role in ribosome biosynthesis, have other functions, including those associated with cancer biology. Some of them can contribute to cell transformation and cancer development. Others, under stress evoked by different factors which often hamper function of nucleoli and thus induce nucleolar/ribosomal stress, can participate in combating cancer cells. In this sense, intentional application of therapeutic agents affecting ribosome biosynthesis can cause either release of these molecules from nucleoli or their de novo biosynthesis to mediate the activation of pathways leading to elimination of harmful cells. This review underlines the role of a nucleolus not only as a ribosome constituting apparatus but also as a hub of both positive and negative control of cancer development. The article is mainly based on original papers concerning mechanisms in which the nucleolus is implicated directly or indirectly in processes associated with neoplasia.