Taxifolin and Lucidin as Potential E6 Protein Inhibitors: p53 Function Re-Establishment and Apoptosis Induction in Cervical Cancer Cells

Programmed Cell Death in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, progressive, systemic autoimmune disease characterised by synovial inflammation, synovial pannus formation and subsequent destruction of articular cartilage and bone. Programmed cell death (PCD), encompassing apoptosis, autophagy, pyroptosis, necroptosis, and ferroptosis, plays a pivotal role in the pathogenesis of RA. An imbalance in PCD causes a variety of immune cells to release large amounts of inflammatory factors and mediators that exacerbate not only chronic synovial inflammation, but also bone and joint damage. The purpose of this article is to review the relevant studies between PCD and RA, with the aim of providing further insights and considerations for a deeper understanding of the pathogenesis of RA and to guide clinical management.

A Perspective on Therapeutic Targeting Against Ubiquitin Ligases to Stabilize Tumor Suppressor Proteins

The loss of functions of tumor suppressor (TS) genes plays a key role in not only tumor initiation but also tumor progression leading to poor prognosis. While therapeutic inhibition of oncogene-encoded kinases has shown clinical success, restoring TS functions remains challenging due to conceptual and technical limitations. E3 ubiquitin ligases that ubiquitinate TS proteins for accelerated degradation in cancers emerge as promising therapeutic targets. Unlike proteasomal inhibitors with a broad spectrum, inhibitors of an E3 ligase would offer superior selectivity and efficacy in enhancing expression of its substrate TS proteins as far as the TS proteins retain wild-type structures. Recent advances in developing E3 inhibitors, including MDM2 inhibitors, highlight their potential and ultimately guide the framework to establish E3 inhibition as effective strategies to treat specific types of cancers. This review explores E3 ligases that negatively regulate bona fide TS proteins, the developmental status of E3 inhibitors, and their promise and pitfalls as therapeutic agents for anti-cancer precision medicine.

Lucidin from Rubia cordifolia Outperforms FDA-Approved Lapatinib as a Potential Multitargeted Candidate for Breast Cancer Signalling Proteins

Background: Breast cancer remains a significant global health concern, with approximately 2.3 million diagnosed cases and 670,000 deaths annually. Current targeted therapies face challenges such as resistance and adverse side effects. This study aimed to explore natural compounds as potential multitargeted breast cancer therapeutics, focusing on Lucidin, an anthraquinone derived from Rubia cordifolia, and comparing its efficacy with Lapatinib, an FDA-approved drug. Methods: We performed multitargeted molecular docking studies on key breast cancer proteins using a natural compound library from ZINC. Comparative analyses of Lucidin and Lapatinib included molecular interaction fingerprints, pharmacokinetics, WaterMap computations (5 ns) to assess water thermodynamics and binding interactions, and Molecular Dynamics Simulations (100 ns) in water to evaluate complex stability and dynamic behaviour. Results: Lucidin demonstrated significant binding affinity and interaction potential with multiple breast cancer targets, outperforming Lapatinib in stability and binding interactions. WaterMap analysis revealed favourable hydration site energetics for Lucidin, enhancing its efficacy. The multitargeted profile of Lucidin suggests a broader therapeutic approach with potential to overcome resistance and side effects associated with Lapatinib. Conclusions: Lucidin shows promise as a novel, multitargeted anti-breast cancer agent with improved efficacy over Lapatinib. These findings provide a foundation for further in vitro and in vivo validation to develop Lucidin as a potential therapeutic option for breast cancer treatment.

Enhanced efficacy of quercetin and taxifolin encapsulated with pH-responsive injectable BSA hydrogel for targeting triple-negative breast cancer cells

Quercetin (QUE) and Taxifolin (TAX) are natural flavonoids with diverse biological activities, holding promise for cancer treatment. However, their clinical application is limited by their poor solubility and bioavailability. Self-assembled bovine serum albumin (BSA) hydrogels have demonstrated biocompatibility and proteolytic stability, making them suitable platforms for drug delivery. The present study validated the anticancer efficacy of QUE, TAX, and DOX encapsulated in BSA hydrogel (QUE@ BSA hydrogel, TAX@ BSA hydrogel, and DOX@ BSA hydrogel), which exhibited 93.5, 90 and 91.2 %% entrapment efficiency, respectively, and controlled release profiles with 90.8,95.8 and 90.8 % drug release, respectively, at lower pH using MDA-MB 231 and MDA-MB 468 TNBC cell lines. Characterization by SEM, XRD, FT-IR and DLS revealed distinctive features of QUE@ BSA hydrogel, TAX@ BSA hydrogel, and DOX@BSA hydrogels, suggesting potential for targeted drug delivery. Further, investigations showed that separate treatment with QUE@BSA hydrogel, TAX@BSA hydrogel, and DOX@BSA hydrogel disrupted cell membrane integrity, akin to inducing cytotoxicity with IC50 of 12.90, 15.52 and 6.9 μM, respectively, in MDA-MB 231 cells and 16.67, 19.16 and 5.2 μM, respectively, in MDA-MB 468 cells. Moreover, they reduced mammosphere formation and cell migration. Additionally, they induced cell cycle arrest, reduced cell proliferation, and induced apoptosis in TNBC cells. They also induced ROS generation and ER stress, highlighting their potential to suppress TNBC progression. Overall, this study underscores the promise of QUE@ BSA hydrogel and TAX@BSA hydrogel as effective anticancer agents against TNBC cell lines in line with DOX@BSA hydrogel, offering controlled drug release and enhanced therapeutic outcomes.

Cytotoxic and Antitumor Agents from Genus Rubia

Genus Rubia is widely distributed in almost all regions of the world, with 36 species and 2 varieties in China. Rubia species, such as Rubia cordifolia, have been used in traditional Chinese medicine for the treatment of diseases since ancient times. In recent years, the study of anticancer effects in traditional Chinese medicine has become a popular topic, and some studies have shown that several Rubia species extracts have cytotoxic and antitumor effects, and some of them have been shown to contain specific antitumor agents. Therefore, this review focuses on the cytotoxic and antitumor effects of the chemical constituents contained in Genus Rubia. Summarized 71 types of chemical substances in 5 categories with the effect of cytotoxicity and antitumor, as well as their structures, targets and mechanisms of action.

Discovery of amino acid-conjugated dimethylcardamonin analogues as potent anti-cervical cancer agents on SiHa cells targeting p53 signalling pathway

DMC (1) is a phytochemical found in the seeds of Syzygium nervosum, exhibiting anticancer activity in various cells through multiple pathways. Herein, the bioactivity of DMC (1) was enhanced by chemical modification through esterification, attaching fatty acid and amino acid moieties to yield 27 semi-synthetic derivatives. These compounds were evaluated for their in vitro cytotoxicity against three main types of cervical cancer cells, including SiHa, HeLa, and C-33A. As a result, the amino acid DMC derivative, 4´-(L-tyrosinyloxy)-DMC (7j), exhibited potent cytotoxicity against SiHa cells, which was approximately two-fold greater than that of 1. Further investigation into the mechanism of action of 7j was conducted, revealing its ability to induce cell cycle arrest and apoptosis. Gene expression analysis showed the downregulation of CDK2 and upregulation of the BAX/BCL2 ratio. Atomistic insight was studied on HPV 16 E6 via molecular dynamics simulation, revealing key interactions between tyrosinyl portion and C51 residue.

Silencing E6/E7 Oncoproteins in SiHa Cells Treated with siRNAs and Oroxylum indicum Extracts Induced Apoptosis by Upregulating p53/pRb Pathways

E6 and E7 human papillomavirus (HPV) oncoproteins play a significant role in the malignant transformation of infected cervical cancer cells via suppression of tumour suppressor pathways by targeting p53 and pRb, respectively. This study aimed to investigate the anticancer effects of Oroxylum indicum (OI) leaves' methanol extract on SiHa cervical cancer cells. Expression of apoptosis-related proteins (Bcl-2, caspase (cas)-3, and cas-9), viral oncoproteins (E6 and E7), and tumour suppressor proteins (p53 and pRb) were evaluated using western blot analysis before and after E6/E7 small interfering RNAs (siRNAs) transfection. In addition, the E6/E7 mRNA expression levels were assessed with real-time (RT)-PCR. The present study showed that the OI extract effectively hindered the proliferation of SiHa cells and instigated increments of cas-3 and cas-9 expressions but decreased the Bcl-2 expressions. The OI extract inhibited E6/E7 viral oncoproteins, leading to upregulation of p53 and pRb tumour suppressor genes in SiHa cells. Additionally, combinatorial treatment of OI extract and gossypin flavonoid induced restorations of p53 and pRb. Treatment with OI extract in siRNA-transfected cells also further suppressed E6/E7 expression levels and further upregulations of p53 and pRb proteins. In conclusion, OI extract treatment on siRNAs-transfected SiHa cells can additively and effectively block E6- and E7-dependent p53 and pRb degradations. All these data suggest that OI could be explored for its chemotherapeutic potential in cervical cancer cells with HPV-integrated genomes.

Taxifolin Inhibits the Growth of Non-Small-Cell Lung Cancer via Downregulating Genes Displaying Novel and Robust Associations with Immune Evasion Factors

Using an LL2 cell-based syngeneic mouse LC model, taxifolin suppressed allografts along with the appearance of 578 differentially expressed genes (DEGs). These DEGs were associated with enhancement of processes related to the extracellular matrix and lymphocyte chemotaxis as well as the reduction in pathways relevant to cell proliferation. From these DEGs, we formulated 12-gene (TxflSig) and 7-gene (TxflSig1) panels; both predicted response to ICB (immune checkpoint blockade) therapy more effectively in non-small-cell lung cancer (NSCLC) than numerous well-established ICB biomarkers, including PD-L1. In both panels, the mouse counterparts of ITGAL, ITGAX, and TMEM119 genes were downregulated by taxifolin. They were strongly associated with immune suppression in LC, evidenced by their robust correlations with the major immunosuppressive cell types (MDSC, Treg, and macrophage) and multiple immune checkpoints in NSCLC and across multiple human cancer types. ITGAL, ITGAX, and IIT (ITGAL-ITGAX-TMEM119) effectively predicted NSCLC's response to ICB therapy; IIT stratified the mortality risk of NSCLC. The stromal expressions of ITGAL and ITGAX, together with tumor expression of TMEM119 in NSCLC, were demonstrated. Collectively, we report multiple novel ICB biomarkers-TxflSig, TxflSig1, IIT, ITGAL, and ITGAX-and taxifolin-derived attenuation of immunosuppressive activities in NSCLC, suggesting the inclusion of taxifolin in ICB therapies for NSCLC.

Taxifolin Inhibits Breast Cancer Growth by Facilitating CD8+ T Cell Infiltration and Inducing a Novel Set of Genes including Potential Tumor Suppressor Genes in 1q21.3

Taxifolin inhibits breast cancer (BC) via novel mechanisms. In a syngeneic mouse BC model, taxifolin suppressed 4T-1 cell-derived allografts. RNA-seq of 4T-1 tumors identified 36 differentially expressed genes (DEGs) upregulated by taxifolin. Among their human homologues, 19, 7, and 2 genes were downregulated in BCs, high-proliferative BCs, and BCs with high-fatality risks, respectively. Three genes were established as tumor suppressors and eight were novel to BC, including HNRN, KPRP, CRCT1, and FLG2. These four genes exhibit tumor suppressive actions and reside in 1q21.3, a locus amplified in 70% recurrent BCs, revealing a unique vulnerability of primary and recurrent BCs with 1q21.3 amplification with respect to taxifolin. Furthermore, the 36 DEGs formed a multiple gene panel (DEG36) that effectively stratified the fatality risk in luminal, HER2+, and triple-negative (TN) equivalent BCs in two large cohorts: the METABRIC and TCGA datasets. 4T-1 cells model human TNBC cells. The DEG36 most robustly predicted the poor prognosis of TNBCs and associated it with the infiltration of CD8+ T, NK, macrophages, and Th2 cells. Of note, taxifolin increased the CD8+ T cell content in 4T-1 tumors. The DEG36 is a novel and effective prognostic biomarker of BCs, particularly TNBCs, and can be used to assess the BC-associated immunosuppressive microenvironment.

Development and Characterization of Quercetin-Loaded Delivery Systems for Increasing Its Bioavailability in Cervical Cancer Cells

Quercetin is a natural flavonoid with high anticancer activity, especially for related-HPV cancers such as cervical cancer. However, quercetin exhibits a reduced aqueous solubility and stability, resulting in a low bioavailability that limits its therapeutic use. In this study, chitosan/sulfonyl-ether-β-cyclodextrin (SBE-β-CD)-conjugated delivery systems have been explored in order to increase quercetin loading capacity, carriage, solubility and consequently bioavailability in cervical cancer cells. SBE-β-CD/quercetin inclusion complexes were tested as well as chitosan/SBE-β-CD/quercetin-conjugated delivery systems, using two types of chitosan differing in molecular weight. Regarding characterization studies, HMW chitosan/SBE-β-CD/quercetin formulations have demonstrated the best results, which are obtaining nanoparticle sizes of 272.07 ± 2.87 nm, a polydispersity index (PdI) of 0.287 ± 0.011, a zeta potential of +38.0 ± 1.34 mV and an encapsulation efficiency of approximately 99.9%. In vitro release studies were also performed for 5 kDa chitosan formulations, indicating a quercetin release of 9.6% and 57.53% at pH 7.4 and 5.8, respectively. IC50 values on HeLa cells indicated an increased cytotoxic effect with HMW chitosan/SBE-β-CD/quercetin delivery systems (43.55 μM), suggesting a remarkable improvement of quercetin bioavailability.

2',4'-Dihydroxy-6'‑methoxy-3',5'-dimethylchalcone and its amino acid-conjugated derivatives induce G0/G1 cell cycle arrest and apoptosis via BAX/BCL2 ratio upregulation and in silico insight in SiHa cell lines

We modified the chemical structure of 2',4'-dihydroxy-6'‑methoxy-3',5'-dimethylchalcone (DMC, 1), a phytochemical found in the seed of Syzygium nervosum A.Cunn. ex DC., by conjugation with the amino acid L-alanine (compound 3a) or L-valine (compound 3b) to enhance anticancer activity and water solubility. Compounds 3a and 3b had antiproliferative activity in human cervical cancer cell lines (C-33A, SiHa and HeLa), with half-maximal inhibitory concentrations (IC₅₀) of 7.56 ± 0.27 and 8.24 ± 0.14 µM, respectively in SiHa cells; these values were approximately two-fold greater than DMC. We investigated the biological activities of compounds 3a and 3b based on a wound healing assay, a cell cycle assay and messenger RNA (mRNA) expression analysis to determine the possible mechanism of anticancer activity. Compounds 3a and 3b inhibited SiHa cell migration in the wound healing assay. After treatment with compounds 3a and 3b, there was an increase in SiHa cells in the G1 phase, indicative of cell cycle arrest. Moreover, compound 3a showed potential anticancer activity by upregulating TP53 and CDKN1A that resulted in upregulation of BAX and downregulation of CDK2 and BCL2, leading to apoptosis and cell cycle arrest. The BAX/BCL2 expression ratio was increased after treatment with compound 3avia the intrinsic apoptotic pathway. In silico molecular dynamics simulation and binding free energy calculation shed light on how these DMC derivatives interact with the HPV16 E6 protein, a viral oncoprotein associated with cervical cancer. Our findings suggest that compound 3a is a potential candidate for anti-cervical cancer drug development.