p53-Independent Effects of Set7/9 Lysine Methyltransferase on Metabolism of Non-Small Cell Lung Cancer Cells

Effects of n-Myc and c-Myc on the expression of p53 family members and their transcriptional targets in human neuroblastoma cells

Neuroblastoma (NB) is an embryonic malignancy causing 15 % of pediatric cancer fatalities. Amplification of the MYCN gene is one of the major NB drivers and biomarkers of high-risk NB. MYCN amplification is associated with high p53-coding gene expression and decreased survival rates in patients. Importantly, only 1-2 % of NB cases harbor TP53 mutations. Moreover, both high TP53 and low MYC expression levels are unfavorable prognostic markers for NB patients, which is not typical for most types of tumors. In this study we analyzed the effect of MYCN amplification on the expression of genes coding p53 family members - TP63 and TP73. We show that, unlike TP53, TP63 and TP73 levels are higher in MYCN-amplified samples. Furthermore, high TP63 and TP73 expression is a favorable prognostic marker for NB patients' survival. That MDM2 inhibition contributes to p53 stabilization and augments the cytotoxic activity of doxorubicin in NB cells prompted us to test the cytotoxic effects of three small-molecule inhibitors of MDM2 that differ in their mechanisms: Nutlin-3a, Mel23, and SP-141. Our results showed that despite the same target, MDM2, these compounds displayed different cytotoxic effects and synergy with doxorubicin on two widely used NB cell lines, IMR-32 and SH-SY5Y that vary in the amount of MDM2 expression. Collectively, our results suggest that except Nutlin-3a, the other two inhibitors, Mel23 and SP-141, employ additional Mdm2-independent mechanisms of cytotoxicity in NB cells that warrants further investigation.

Lysine methyltransferase SETD7 in cancer: functions, molecular mechanisms and therapeutic implications

Since its discovery as a histone methyltransferase, SETD7 has been implicated in many signaling pathways and carcinogenesis. SETD7 catalyzes the methylation of histone H3 and non-histone proteins, regulating their translation, stability and activity. SETD7 is frequently abnormally expressed and has a significant influence on cell proliferation, invasion, autophagy and immune response. As cancer is a complex disease, an outstanding concept in cancer biology is the "hallmarks of cancer". In this review, we focus on the involvement of SETD7 in the hallmarks of cancer, describing its functions and underlying mechanisms in detail. Additionally, we discuss non-coding RNAs and chemical inhibitors targeting SETD7, highlighting the potential and importance of SETD7 in cancer therapy.

MDM2 up-regulates the energy metabolism in NSCLC in a p53-independent manner

Although an E3 ligase MDM2 is the major negative regulator of the p53 tumor suppressor, a growing body of evidence suggests its p53-independent oncogenic properties. In particular, MDM2 has been shown to regulate serine metabolism independently of p53 status in several types of neoplasia, including NSCLC. Using the GSEA approach and publicly available molecular data on NSCLC tumors, our bioinformatics data suggest that MDM2 affects a number of metabolic genes, particularly those encoding components of the electron transport chain (ETC). To experimentally elucidate the role of MDM2 in respiration and energy metabolism of NSCLC cell models, we established NSCLC cell lines (WT p53+ A549 and p53-null H1299) overexpressing wild-type MDM2, or its catalytically deficient (C464A) mutant (MUT), or the control vector. Using TMRE staining and SeaHorse energy profiling, we demonstrated that wild-type MDM2, but not its catalytically inactive mutant, significantly increased mitochondrial membrane potential (MMP), glycolysis, respiration, and ATP production in a p53-independent manner. Further, we compared MDM2-associated effects of two natural compounds that, according to our docking experiment data, bind MDM2 with affinities similar to nutlin-3A, ganoderic acid A and berberine. Despite the fact that both nutlin-3A and berberine stabilized the MDM2 protein, they displayed differential effects on energy metabolism. Taken together, our data argue that MDM2 affects energy metabolism likely in a p53-independent manner. These results also highlight another pharmacological dimension of using MDM2-targeting compounds as potent inhibitors of glycolysis and respiration in tumor cells.

Effect of infection by Mycoplasma arginini and Mycoplasma salivarium on the oncogenic properties of lung cancer cell line A549

Most mycoplasma species are the extracellular parasites affecting different cellular processes including proliferation, cell cycle, protein synthesis, DNA repair and others. Mycoplasma infection was shown to contribute to the pathology of various diseases, including cancer. Upon infection, mycoplasmas typically activate the tumor-associated NF-kB pathway, which is associated with EMT, the main mechanism of metastasis. In this study, we found that two different mycoplasma strains, M. arginini and M. salivarium, promoted the initiation of EMT and simultaneous suppression of the p53 tumor suppressor in A549 lung cancer cells. This led to an increase of cancer cell motility, resistance to the antitumor drug etoposide concomitantly with decreased autophagy. These data indicate that mycoplasmas are able to increase the tumorigenic potential of cancer host cells.

Lysine-specific methyltransferase Set7/9 in stemness, differentiation, and development

The enzymes performing protein post-translational modifications (PTMs) form a critical post-translational regulatory circuitry that orchestrates literally all cellular processes in the organism. In particular, the balance between cellular stemness and differentiation is crucial for the development of multicellular organisms. Importantly, the fine-tuning of this balance on the genetic level is largely mediated by specific PTMs of histones including lysine methylation. Lysine methylation is carried out by special enzymes (lysine methyltransferases) that transfer the methyl group from S-adenosyl-L-methionine to the lysine residues of protein substrates. Set7/9 is one of the exemplary protein methyltransferases that however, has not been fully studied yet. It was originally discovered as histone H3 lysine 4-specific methyltransferase, which later was shown to methylate a number of non-histone proteins that are crucial regulators of stemness and differentiation, including p53, pRb, YAP, DNMT1, SOX2, FOXO3, and others. In this review we summarize the information available to date on the role of Set7/9 in cellular differentiation and tissue development during embryogenesis and in adult organisms. Finally, we highlight and discuss the role of Set7/9 in pathological processes associated with aberrant cellular differentiation and self-renewal, including the formation of cancer stem cells.

Methyltransferase Set7/9 controls PARP1 expression and regulates cisplatin response of breast cancer cells

The protein-specific methyltransferase Set7/9 is known for its ability to add methyl groups to lysine residues on many targets, including as histones H1.4, H2A, H2B, H3, and non-histone proteins such as p53, NFκB, E2F1, pRb, Hif1α, β-catenin, STAT3, and YY1 transcription factors. Set7/9 affects both the landscape of histone modifications and the functionality of the aforementioned TFs, and acts as an essential mediator of vital cellular functions, regulating tumor growth and the neoplastic transformation of normal cells. The number of studies demonstrating the determining role of Set7/9 in cancer is growing. Importantly, the effect of Set7/9 on tumor progression is ambivalent and cancer-type dependent. In this study we analyzed the potential participation of Set7/9 in the essential cellular processes in breast cancer cells and revealed that Set7/9 may be involved in DNA damage signaling and DNA repair processes. We further demonstrated that Set7/9 expression is downregulated in cancerous breast tissues and inversely correlated to PARP1 expression level. Using breast cancer cell lines of HER2-positive and triple negative subtypes we have shown that the attenuation of Set7/9 led to the stabilization of PARP1 on both mRNA and protein levels that in turn resulted in cisplatin resistance acquiring. Finally, we demonstrated that the combination of cisplatin with FDA approved PARP1 inhibitor niraparib (Zejula) has a synergistic effect with cisplatin and thereby allows to overcome cisplatin resistance of Set7/9 deficient breast cancer cells.

Phytochemicals Target Multiple Metabolic Pathways in Cancer

Cancer metabolic reprogramming is a complex process that provides malignant cells with selective advantages to grow and propagate in the hostile environment created by the immune surveillance of the human organism. This process underpins cancer proliferation, invasion, antioxidant defense, and resistance to anticancer immunity and therapeutics. Perhaps not surprisingly, metabolic rewiring is considered to be one of the "Hallmarks of cancer". Notably, this process often comprises various complementary and overlapping pathways. Today, it is well known that highly selective inhibition of only one of the pathways in a tumor cell often leads to a limited response and, subsequently, to the emergence of resistance. Therefore, to increase the overall effectiveness of antitumor drugs, it is advisable to use multitarget agents that can simultaneously suppress several key processes in the tumor cell. This review is focused on a group of plant-derived natural compounds that simultaneously target different pathways of cancer-associated metabolism, including aerobic glycolysis, respiration, glutaminolysis, one-carbon metabolism, de novo lipogenesis, and β-oxidation of fatty acids. We discuss only those compounds that display inhibitory activity against several metabolic pathways as well as a number of important signaling pathways in cancer. Information about their pharmacokinetics in animals and humans is also presented. Taken together, a number of known plant-derived compounds may target multiple metabolic and signaling pathways in various malignancies, something that bears great potential for the further improvement of antineoplastic therapy.

20-Hydroxyecdysone Confers Antioxidant and Antineoplastic Properties in Human Non-Small Cell Lung Cancer Cells

20-Hydroxyecdysone (20E) is an arthropod hormone which is synthesized by some plants as part of their defense mechanism. In humans, 20E has no hormonal activity but possesses a number of beneficial pharmacological properties including anabolic, adaptogenic, hypoglycemic, and antioxidant properties, as well as cardio-, hepato-, and neuroprotective features. Recent studies have shown that 20E may also possess antineoplastic activity. In the present study, we reveal the anticancer properties of 20E in Non-Small Cell Lung Cancer (NSCLC) cell lines. 20E displayed significant antioxidant capacities and induced the expression of antioxidative stress response genes. The RNA-seq analysis of 20E-treated lung cancer cells revealed the attenuation of genes involved in different metabolic processes. Indeed, 20E suppressed several enzymes of glycolysis and one-carbon metabolism, as well as their key transcriptional regulators-c-Myc and ATF4, respectively. Accordingly, using the SeaHorse energy profiling approach, we observed the inhibition of glycolysis and respiration mediated by 20E treatment. Furthermore, 20E sensibilized lung cancer cells to metabolic inhibitors and markedly suppressed the expression of Cancer Stem Cells (CSCs) markers. Thus, in addition to the known beneficial pharmacological activities of 20E, our data uncovered novel antineoplastic properties of 20E in NSCLC cells.

Methyltransferase Set7/9 as a Multifaceted Regulator of ROS Response

Reactive oxygen species (ROS) induce multiple signaling cascades in the cell and hence play an important role in the regulation of the cell's fate. ROS can cause irreversible damage to DNA and proteins resulting in cell death. Therefore, finely tuned regulatory mechanisms exist in evolutionarily diverse organisms that are aimed at the neutralization of ROS and its consequences with respect to cellular damage. The SET domain-containing lysine methyltransferase Set7/9 (KMT7, SETD7, SET7, SET9) post-translationally modifies several histones and non-histone proteins via monomethylation of the target lysines in a sequence-specific manner. In cellulo, the Set7/9-directed covalent modification of its substrates affects gene expression, cell cycle, energy metabolism, apoptosis, ROS, and DNA damage response. However, the in vivo role of Set7/9 remains enigmatic. In this review, we summarize the currently available information regarding the role of methyltransferase Set7/9 in the regulation of ROS-inducible molecular cascades in response to oxidative stress. We also highlight the in vivo importance of Set7/9 in ROS-related diseases.

How Should the Worldwide Knowledge of Traditional Cancer Healing Be Integrated with Herbs and Mushrooms into Modern Molecular Pharmacology?

Traditional herbal medicine (THM) is a "core" from which modern medicine has evolved over time. Besides this, one third of people worldwide have no access to modern medicine and rely only on traditional medicine. To date, drugs of plant origin, or their derivates (paclitaxel, vinblastine, vincristine, vinorelbine, etoposide, camptothecin, topotecan, irinotecan, and omacetaxine), are very important in the therapy of malignancies and they are included in most chemotherapeutic regimes. To date, 391,000 plant and 14,000 mushroom species exist. Their medical and biochemical capabilities have not been studied in detail. In this review, we systematized the information about plants and mushrooms, as well as their active compounds with antitumor properties. Plants and mushrooms are divided based on the regions where they are used in ethnomedicine to treat malignancies. The majority of their active compounds with antineoplastic properties and mechanisms of action are described. Furthermore, on the basis of the available information, we divided them into two priority groups for research and for their potential of use in antitumor therapy. As there are many prerequisites and some examples how THM helps and strengthens modern medicine, finally, we discuss the positive points of THM and the management required to transform and integrate THM into the modern medicine practice.

Zeb1-mediated autophagy enhances resistance of breast cancer cells to genotoxic drugs

Autophagy is a highly conserved process of cellular self-digestion that involves the formation of autophagosomes for the delivery of intracellular components and dysfunctional organelles to lysosomes. This process is induced by different signals including starvation, mitochondrial dysfunction, and DNA damage. The molecular link between autophagy and DNA damage is not well understood yet. Importantly, tumor cells utilize the mechanism of autophagy to cope with genotoxic anti-cancer drug therapy. Another mechanism of drug resistance is provided to cancer cells via the execution of the EMT program. One of the critical transcription factors of EMT is Zeb1. Here we demonstrate that Zeb1 is involved in the regulation of autophagy in several breast cancer cell models. On the molecular level, Zeb1 likely facilitates autophagy through the regulation of autophagic genes, resulting in increased LC3-II levels, augmented staining with Lysotracker, and increased resistance to several genotoxic drugs. The attenuation of Zeb1 expression in TNBC cells led to the opposite effect. Consequently, we propose that Zeb1 augments the resistance of breast cancer cells to genotoxic drugs, at least partially, via autophagy. Collectively, we have uncovered a novel function of Zeb1 in the regulation of autophagy in breast cancer cells.