Butein activates p53 in hepatocellular carcinoma cells via blocking MDM2-mediated ubiquitination

Significance of Chalcone Scaffolds in Medicinal Chemistry

Chalcone is a simple naturally occurring α,β-unsaturated ketone with biological importance, which can also be easily synthesized in laboratories by reaction between two aromatic scaffolds. In plants, chalcones occur as polyphenolic compounds of different frameworks which are bioactive molecules that have been in traditional medicinal practice for many years. Chalcone-based lead molecules have been developed, possessing varied potentials such as antimicrobial, antiviral, anti-inflammatory, anticancer, anti-oxidant, antidiabetic, antihyperurecemic, and anti-ulcer effects. Chalcones contribute considerable fragments to give important heterocyclic molecules with therapeutic utilities targeting various diseases. These characteristic features have made chalcone a topic of interest among researchers and have attracted investigations into this widely applicable structure. This review highlights the extensive exploration carried out on the synthesis, biotransformations, chemical reactions, hybridization, and pharmacological potentials of chalcones, and aims to provide an extensive, thorough, and critical review of their importance, with emphasis on their properties, chemistry, and biomedical applications to boost future investigations into this potential scaffold in medicinal chemistry.

Butein inhibits cancer cell growth by rescuing the wild-type thermal stability of mutant p53

p53 is a transcription factor that activates the expression of various genes involved in the maintenance of genomic stability, and more than 50% of cancers harbor inactivating p53 mutations, which are indicative of highly aggressive cancer and poor prognosis. Pharmacological targeting of mutant p53 to restore the wild-type p53 tumor-suppressing function is a promising strategy for cancer therapy. In this study, we identified a small molecule, Butein, that reactivates mutant p53 activity in tumor cells harboring the R175H or R273H mutation. Butein restored wild-type-like conformation and DNA-binding ability in HT29 and SK-BR-3 cells harboring mutant p53-R175H and mutant p53-R273H, respectively. Moreover, Butein enabled the transactivation of p53 target genes and decreased the interactions of Hsp90 with mutant p53-R175H and mutant p53-R273H proteins, while Hsp90 overexpression reversed targeted p53 gene activation. In addition, Butein induced thermal stabilization of wild-type p53, mutant p53-R273H and mutant p53-R175H, as determined via CETSA. From docking study, we further proved that Butein binding to p53 stabilized the DNA-binding loop-sheet-helix motif of mutant p53-R175H and regulated its DNA-binding activity via an allosteric mechanism, conferring wild-type-like the DNA-binding activity of mutant p53. Collectively, the data suggest that Butein is a potential antitumor agent that restores p53 function in cancers harboring mutant p53-R273H or mutant p53-R175H. SIGNIFICANCE: Butein restores the ability of mutant p53 to bind DNA by reversing its transition to the Loop3 (L3) state, endows p53 mutants with thermal stability and re-establishes their transcriptional activity to induce cancer cell death.

Butein and Frondoside-A Combination Exhibits Additive Anti-Cancer Effects on Tumor Cell Viability, Colony Growth, and Invasion and Synergism on Endothelial Cell Migration

Despite the significant advances in targeted- and immuno-therapies, lung and breast cancer are at the top list of cancer incidence and mortality worldwide as of 2020. Combination therapy consisting of a mixture of different drugs taken at once is currently the main approach in cancer management. Natural compounds are extensively investigated for their promising anti-cancer potential. This study explored the anti-cancer potential of butein, a biologically active flavonoid, on two major solid tumors, namely, A549 lung and MDA-MB-231 breast cancer cells alone and in combination with another natural anti-cancer compound, frondoside-A. We demonstrated that butein decreases A549 and MDA-MB-231 cancer cell viability and colony growth in vitro in addition to tumor growth on chick embryo chorioallantoic membrane (CAM) in vivo without inducing any noticeable toxicity. Additionally, non-toxic concentrations of butein significantly reduced the migration and invasion of both cell lines, suggesting its potential anti-metastatic effect. We showed that butein anti-cancer effects are due, at least in part, to a potent inhibition of STAT3 phosphorylation, leading to PARP cleavage and consequently cell death. Moreover, we demonstrated that combining butein with frondoside-A leads to additive effects on inhibiting A549 and MDA-MB-231 cellular viability, induction of caspase 3/7 activity, inhibition of colony growth, and inhibition of cellular migration and invasion. This combination reached a synergistic effect on the inhibition of HUVECs migration in vitro. Collectively, this study provides sufficient rationale to further carry out animal studies to confirm the relevance of these compounds’ combination in cancer therapy.

Molecular mechanisms underlying chemopreventive potential of butein: Current trends and future perspectives

Despite extensive efforts, cancer is still often considered as an incurable disease and initiation of novel drug development programs is crucial to improve the prognosis and clinical outcome of patients. One of the major approaches in designing the novel cancer drugs has historically comprised studies of natural agents with diverse anticancer properties. As only a marginal part of natural compounds has been investigated, this approach still represents an attractive source of new potential antitumor molecules. In this review article, different anticancer effects of plant-derived chalcone, butein, are discussed, including its growth inhibitory action, proapoptotic, antiangiogenic and antimetastatic activities in a variety of cancer cells. The molecular mechanisms underlying these effects are presented in detail, revealing interactions of butein with multiple cellular targets (Bcl-2/Bax, caspases, STAT3, cyclins, NF-κB, COX-2, MMP-9, VEGF/R etc.) and regulation of a wide range of intracellular signal transduction pathways. These data altogether allow a good basis for initiating further in vivo studies as well as clinical trials. Along with the efforts to overcome low bioavailability issues generally characteristic to plant metabolites, butein can be considered as a potential lead compound for safe and more efficient cancer drugs in the future.

Ubiquitin pathways regulate the pathogenesis of chronic liver disease

Chronic liver disease (CLD) is considered the leading cause of global mortality. In westernized countries, increased consumption of alcohol and overeating foods with high fat/ high glucose promote progression of CLD such as alcoholic liver disease (ALD) and non-alcoholic liver disease (NAFLD). Accumulating evidence and research suggest that ubiquitin, a 75 amino acid protein, plays crucial role in the pathogenesis of CLD through dynamic post-translational modifications (PTMs) exerting diverse cellular outcomes such as protein degradation through ubiquitin-proteasome system (UPS) and autophagy, and regulation of signal transduction. In this review, we present the function of ubiquitination and latest findings on diverse mechanism of PTMs, UPS and autophagy which significantly contribute to the pathogenesis of alcoholic liver disease (ALD), non-alcoholic fatty liver disease (NAFLD), cirrhosis, and HCC. Despite its high prevalence, morbidity, and mortality, there are only few FDA approved drugs that could be administered to CLD patients. The goal of this review is to present a variety of pathways and therapeutic targets involving ubiquitination in the pathogenesis of CLD. Further, this review summarizes collective views of pharmaceutical inhibition or activation of recent drugs targeting UPS and autophagy system to highlight potential targets and new approaches to treat CLD.

Molecular Mechanisms of Antiproliferative Effects of Natural Chalcones

Simple Summary

Despite the important progress in cancer treatment in the past decades, the mortality rates in some types of cancer have not significantly decreased. Therefore, the search for novel anticancer drugs has become a topic of great interest. Chalcones, precursors of flavonoid synthesis in plants, have been documented as natural compounds with pleiotropic biological effects including antiproliferative/anticancer activity. This article focuses on the knowledge on molecular mechanisms of antiproliferative action of chalcones and draws attention to this group of natural compounds that may be of importance in the treatment of cancer disease.

Abstract

Although great progress has been made in the treatment of cancer, the search for new promising molecules with antitumor activity is still one of the greatest challenges in the fight against cancer due to the increasing number of new cases each year. Chalcones (1,3-diphenyl-2-propen-1-one), the precursors of flavonoid synthesis in higher plants, possess a wide spectrum of biological activities including antimicrobial, anti-inflammatory, antioxidant, and anticancer. A plethora of molecular mechanisms of action have been documented, including induction of apoptosis, autophagy, or other types of cell death, cell cycle changes, and modulation of several signaling pathways associated with cell survival or death. In addition, blockade of several steps of angiogenesis and proteasome inhibition has also been documented. This review summarizes the basic molecular mechanisms related to the antiproliferative effects of chalcones, focusing on research articles from the years January 2015–February 2021.

Butein induces cellular senescence through reactive oxygen species-mediated p53 activation in osteosarcoma U-2 OS cells

Butein is a flavonoid isolated from various medicinal plants. It is known to have different biological activities including anti-inflammation, anti-adipogenesis, and anti-angiogenesis. In the study, we demonstrated the anti-proliferative effect of butein in human osteosarcoma U-2 OS cells. Our data showed that butein significantly suppressed the viability and colony formation ability of U-2 OS cells. Further experiments revealed butein exposure resulted in a cell cycle arrest at S and G2/M phase in U-2 OS cells. Importantly, we found that butein activated the tumor suppressor p53, and trigged a p53-dependent senescence in U-2 OS cells. Knockdown of p53 suppressed the senescence and rescued the viability in butein-treated U-2 OS cells. Furthermore, we observed that butein exposure significantly enhanced reactive oxygen species (ROS) levels in U-2 OS cells. Co-administration of the ROS inhibitor NAC largely abolished the up-regulated p53 protein level, and rescued the suppressed viability and colony formation ability in butein-exposed U-2 OS cells. Taken together, our data proposed the increased ROS by butein exposure activated p53, and the activated p53 was involved in the anti-proliferative effect of butein via inducing senescence in U-2 OS cells. This report suggests that butein is a promising candidate for cancer therapy against osteosarcoma.

Gene expression profile involved in signaling and apoptosis of osteoblasts in contact with cellulose/MWCNTs scaffolds

The aim of this work was to evaluate the expression profile of genes involved in signaling, intracellular and extracellular Ca⁺² concentration and apoptosis pathways of osteoblasts in contact with a scaffold made of a composite of BCN/MWCNTs. Osteoblasts were cultivated on BCN, MWCNTs and their mixtures. Osteoblast RNA was extracted for sintering cDNA to amplify genes of interest by PCR; intra- and extracellular calcium (Ca²⁺⁾ was also quantified. Regarding the genes that participate in the regulation paths (MAPK and NF-KB), it was found that only the expression of NF-KB was affected in all treatments. The expression of VEGFA increased, except in the treatment of high concentration of MWCNTs, where remained unchanged. The expression of genes Apaf-1 and Bcl-2/Bax and TP53 increased as compared to the control (except for TP53 in BC and C1/MWCNTs) indicating that cells are responding to the presence of BCN-MWCNTs composites scaffolds. The results suggest that osteoblast developed a modification in the expression profile of genes that actively participate in cellular processes such as proliferation, vasculogenesis and apoptosis, which may be modulated by the increase of intra- and extracellular Ca²⁺ concentration.

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.