SKLB-M8 Induces Apoptosis Through the AKT/mTOR Signaling Pathway in Melanoma Models and Inhibits Angiogenesis With Decrease of ERK1/2 Phosphorylation

Flavonoids with Anti-Angiogenesis Function in Cancer

The formation of new blood vessels, known as angiogenesis, significantly impacts the development of multiple types of cancer. Consequently, researchers have focused on targeting this process to prevent and treat numerous disorders. However, most existing anti-angiogenic treatments rely on synthetic compounds and humanized monoclonal antibodies, often expensive or toxic, restricting patient access to these therapies. Hence, the pursuit of discovering new, affordable, less toxic, and efficient anti-angiogenic compounds is imperative. Numerous studies propose that natural plant-derived products exhibit these sought-after characteristics. The objective of this review is to delve into the anti-angiogenic properties exhibited by naturally derived flavonoids from plants, along with their underlying molecular mechanisms of action. Additionally, we summarize the structure, classification, and the relationship between flavonoids with their signaling pathways in plants as anti-angiogenic agents, including main HIF-1α/VEGF/VEGFR2/PI3K/AKT, Wnt/β-catenin, JNK1/STAT3, and MAPK/AP-1 pathways. Nonetheless, further research and innovative approaches are required to enhance their bioavailability for clinical application.

A review on Millepachine and its derivatives as potential multitarget anticancer agents

Chalcones have a long history of being used for many medical purposes. These are the most prestigious scaffolds in medicine. The potential of Millepachine and its derivatives to treat various malignancies has been demonstrated in this review. The anticancer effects of Millepachine and its derivatives on ovarian cancer, hepatocellular carcinoma, breast, liver, colon, cervical, prostate, stomach, and gliomas are highlighted in the current review. Several genes that are crucial in reducing the severity of the disease have been altered by these substances. They mainly work by preventing tubulin polymerizing. They also exhibit apoptosis and cell cycle arrest at the G2/M phase. Additionally, these compounds inhibit invasion and migration and have antiproliferative effects. Preclinical studies have shown that Millepachine and its derivatives offer exceptional potential for treating a number of cancers. These results need to be confirmed in clinical research in order to develop viable cancer therapies.

Kinase Inhibitors in Genetic Diseases

Over the years, several studies have shown that kinase-regulated signaling pathways are involved in the development of rare genetic diseases. The study of the mechanisms underlying the onset of these diseases has opened a possible way for the development of targeted therapies using particular kinase inhibitors. Some of these are currently used to treat other diseases, such as cancer. This review aims to describe the possibilities of using kinase inhibitors in genetic pathologies such as tuberous sclerosis, RASopathies, and ciliopathies, describing the various pathways involved and the possible targets already identified or currently under study.

Targeting mTOR as a Cancer Therapy: Recent Advances in Natural Bioactive Compounds and Immunotherapy

The mammalian target of rapamycin (mTOR) is a highly conserved serine/threonine-protein kinase, which regulates many biological processes related to metabolism, cancer, immune function, and aging. It is an essential protein kinase that belongs to the phosphoinositide-3-kinase (PI3K) family and has two known signaling complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). Even though mTOR signaling plays a critical role in promoting mitochondria-related protein synthesis, suppressing the catabolic process of autophagy, contributing to lipid metabolism, engaging in ribosome formation, and acting as a critical regulator of mRNA translation, it remains one of the significant signaling systems involved in the tumor process, particularly in apoptosis, cell cycle, and cancer cell proliferation. Therefore, the mTOR signaling system could be suggested as a cancer biomarker, and its targeting is important in anti-tumor therapy research. Indeed, its dysregulation is involved in different types of cancers such as colon, neck, cervical, head, lung, breast, reproductive, and bone cancers, as well as nasopharyngeal carcinoma. Moreover, recent investigations showed that targeting mTOR could be considered as cancer therapy. Accordingly, this review presents an overview of recent developments associated with the mTOR signaling pathway and its molecular involvement in various human cancer types. It also summarizes the research progress of different mTOR inhibitors, including natural and synthetised compounds and their main mechanisms, as well as the rational combinations with immunotherapies.

Kaempferol, the melanogenic component of Sanguisorba officinalis, enhances dendricity and melanosome maturation/transport in melanocytes

Kaempferol, a representative flavonoid constituent of Sanguisorba officinalis, promotes melanogenesis, but the underlying mechanisms remain unknown. Here, we evaluated the effects of kaempferol on melanocytes morphology and behavior and determined the mechanisms regulating kaempferol-induced pigmentation. We observed that kaempferol increased melanin contents and dendritic length and stimulated melanocyte migration both in vitro and vivo. It significantly enhanced the expression of microphthalmia-associated transcription factor (MITF) and downstream enzymes of melanin biosynthesis-tyrosinase (TYR), tyrosinase-related protein (TRP-1), and dopachrome tautomerase (DCT). It also induced melanosome maturation (increased stage III and IV melanosomes) and melanin transfer to dendritic tips; this was evidenced as follows: kaempferol-treated melanocytes exhibited the perimembranous accumulation of HMB45-positive melanosomes and increased the expression of Rab27A, RhoA, and Cdc42, which improved melanosome transport to perimembranous actin filaments. These results jointly indicated that kaempferol promotes melanogenesis and melanocyte growth. Additionally, kaempferol stimulated the phosphorylation of P38/ERK MAPK and downregulated p-PI3K, p-AKT, and p-P70s6K expression. Pre-incubation with P38 (SB203580) and ERK (PD98059) signaling inhibitors reversed the melanogenic and dendritic effects and MITF expression. PI3K/AKT inhibitor augmented kaempferol-induced melanin content and dendrite length. In summary, kaempferol regulated melanocytes' dendritic growth and melanosome quantity, maturation, and transport via P38/ERK MAPK and PI3K/AKT signaling pathways.

Chalcones as Promising Antitumor Agents by Targeting the p53 Pathway: An Overview and New Insights in Drug-Likeness

The p53 protein is one of the most important tumor suppressors that are frequently inactivated in cancer cells. This inactivation occurs either because the TP53 gene is mutated or deleted, or due to the p53 protein inhibition by endogenous negative regulators, particularly murine double minute (MDM)2. Therefore, the reestablishment of p53 activity has received great attention concerning the discovery of new cancer therapeutics. Chalcones are naturally occurring compounds widely described as potential antitumor agents through several mechanisms, including those involving the p53 pathway. The inhibitory effect of these compounds in the interaction between p53 and MDM2 has also been recognized, with this effect associated with binding to a subsite of the p53 binding cleft of MDM2. In this work, a literature review of natural and synthetic chalcones and their analogues potentially interfering with p53 pathway is presented. Moreover, in silico studies of drug-likeness of chalcones recognized as p53-MDM2 interaction inhibitors were accomplished considering molecular descriptors, biophysiochemical properties, and pharmacokinetic parameters in comparison with those from p53-MDM2 in clinical trials. With this review, we expect to guide the design of new and more effective chalcones targeting the p53 pathway.

MCM7 silencing promotes cutaneous melanoma cell autophagy and apoptosis by inactivating the AKT1/mTOR signaling pathway

Cutaneous melanoma (CM) has become a major public health concern. Studies illustrate that minichromosome maintenance protein 7 (MCM7) participate in various diseases including skin disease. Our study aimed to study the effects of MCM7 silencing on CM cell autophagy and apoptosis by modulating the AKT threonine kinase 1 (AKT1)/mechanistic target of rapamycin kinase (mTOR) signaling pathway. Initially, microarray analysis was used to screen the CM-related gene expression data as well as differentially expressed genes. Subsequently, MCM7 expression vector and lentivirus RNA used for MCM7 silencing (LV-shRNA-MCM7) were constructed, and these vectors, dimethyl sulfoxide (DMSO) and AKT activator SC79 were then introduced into CM cell line SK-MEL-2 to validate the role of MCM7 in cell autophagy, viability, apoptosis, cell cycle, migration, and invasion. To further investigate the regulatory mechanisms of MCM7 in CM progress, the expression of MCM7, AKT1, mTOR, cyclin D1, as well as autophagy and apoptosis relative factors, such as LC3B, SOD2, DJ-1, p62, Bcl-2, Bax, and caspase-3 in melanoma cells was determined. MCM7 might mediate the AKT1/mTOR signaling pathway to influence the progress of melanoma. MCM7 silencing contributed to the increased expression of Bax, capase-3, and autophagy-related genes (LC3B, SOD2, and DJ-1), but decreased the expression of Bcl-2, which suggested that MCM7 silencing promoted autophagy and cell apoptosis. At the same time, MCM7 silencing also attenuated cell viability, invasion, and migration, and reduced the cyclin D1 expression and protein levels of p-AKT1 and p-mTOR. Taken together, MCM7 silencing inhibited CM via inactivation of the AKT1/mTOR signaling pathway.

Role and Therapeutic Targeting of the PI3K/Akt/mTOR Signaling Pathway in Skin Cancer: A Review of Current Status and Future Trends on Natural and Synthetic Agents Therapy

The mammalian or mechanistic target of rapamycin (mTOR) and associated phosphatidyl-inositiol 3-kinase (PI3K)/protein kinase B (Akt) pathways regulate cell growth, differentiation, migration, and survival, as well as angiogenesis and metabolism. Dysregulation of these pathways is frequently associated with genetic/epigenetic alterations and predicts poor treatment outcomes in a variety of human cancers including cutaneous malignancies like melanoma and non-melanoma skin cancers. Recently, the enhanced understanding of the molecular and genetic basis of skin dysfunction in patients with skin cancers has provided a strong basis for the development of novel therapeutic strategies for these obdurate groups of skin cancers. This review summarizes recent advances in the roles of PI3K/Akt/mTOR and their targets in the development and progression of a broad spectrum of cutaneous cancers and discusses the current progress in preclinical and clinical studies for the development of PI3K/Akt/mTOR targeted therapies with nutraceuticals and synthetic small molecule inhibitors.

Antiangiogenic Effect of Flavonoids and Chalcones: An Update

Chalcones are precursors of flavonoid biosynthesis in plants. Both flavonoids and chalcones are intensively investigated because of a large spectrum of their biological activities. Among others, anticancer and antiangiogenic effects account for the research interest of these substances. Because of an essential role in cancer growth and metastasis, angiogenesis is considered to be a promising target for cancer treatment. Currently used antiangiogenic agents are either synthetic compounds or monoclonal antibodies. However, there are some limitations of their use including toxicity and high price, making the search for new antiangiogenic compounds very attractive. Nowadays it is well known that several natural compounds may modulate basic steps in angiogenesis. A lot of studies, also from our lab, showed that phytochemicals, including polyphenols, are potent modulators of angiogenesis. This review paper is focused on the antiangiogenic effect of flavonoids and chalcones and discusses possible underlying cellular and molecular mechanisms.

Innate immune cell activation and epigenetic remodeling in symptomatic and asymptomatic atherosclerosis in humans in vivo

BACKGROUND AND AIMS

We have recently reported that monocytes can undergo functional and transcriptional reprogramming towards a long-term pro-inflammatory phenotype after brief in vitro exposure to atherogenic stimuli such as oxidized LDL. This process is termed 'trained immunity', and is mediated by epigenetic remodeling and a metabolic switch towards increased aerobic glycolysis. We hypothesize that trained immunity contributes to atherogenesis. Therefore, we investigated the inflammatory phenotype and epigenetic remodeling of monocytes from patients with and without established atherosclerosis.

METHODS

Monocytes were isolated from 20 patients with severe symptomatic coronary atherosclerosis (total plaque score >4 on coronary computed tomography angiography) and 17 patients with asymptomatic carotid atherosclerosis and matched controls for both groups. Ex vivo stimulation, RNA analysis and chromatin immunoprecipitation were performed.

RESULTS

Monocytes from patients with symptomatic atherosclerosis have a higher production of pro-inflammatory cytokines upon LPS stimulation than healthy controls (TNFα 499 ± 102 vs. 267 ± 45 pg/ml, p = 0.01). This was associated with lower histone 3 lysine 4 trimethylation (H3K4me3) (19% vs. 33%, p = 0.002), and lower H3K27me3 (0.005% vs. 0.8%, p < 0.0001) on the TNFα promoter. Furthermore, relative mRNA expression of the glycolytic rate limiting enzymes hexokinase 2 and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 was higher in patients (0.7 ± 0.2 vs. 0.3 ± 0.1 resp. 1.7 ± 0.2 vs. 1.0 ± 0.1, p = 0.007 resp. 0.003) compared to control individuals. Interestingly, this pro-inflammatory phenotype was only present in patients with symptomatic atherosclerosis, and not in patients with asymptomatic carotid atherosclerosis.

CONCLUSIONS

Circulating monocytes of patients with symptomatic, but not asymptomatic, atherosclerosis have a pro-inflammatory phenotype and increased expression of glycolytic enzymes, associated with epigenetic remodeling at the level of histone methylation.

Isoorientin from Gypsophila elegans induces apoptosis in liver cancer cells via mitochondrial-mediated pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Gypsophila elegans has been used as a traditional herbal medicine for treating immune disorders and chronic liver diseases in China. The aim of this study is to isolate an active ingredient from this herb and investigate its anti-tumor activity.

MATERIALS AND METHODS

An active ingredient was isolated from the ethanol extract using bioassay-guided screening. And its anti-tumor activity was analyzed by testing the cytotoxicity, lactate dehydrogenase (LDH) release, clonogenecity and migration in HepG2 cells. To investigate its potential mechanism, cell apoptosis, cell cycle arrest, reactive oxygen species (ROS), cytochrome c, mitochondria membrane potential (MMP) and caspase level were determined in liver cancer cell line HepG2.

RESULTS

A flavonoid glycoside, i.e., G. elegans isoorientin (GEI), was isolated from this herb and identified as Isoorientin-2″-O-α-l-arabinopyranosyl. Our results showed that GEI significantly inhibited the viability and proliferation of HepG2 cells in a dose- and time-dependent manner, and its cytotoxic effect was also confirmed by the elevated level of LDH. GEI treatment could markedly inhibit the clonogenicity and migration of HepG2 cells. Moreover, GEI induced remarkable apoptotic death of HepG2 cells through cell cycle arrest at G1 phase via the regulation of cell cycle-related genes, such as cyclin D, cyclin E and CDK2. Further study showed that GEI treatment significantly elevated ROS formation, followed by attenuation of MMP via up-regulation of Bax and down-regulation of Bcl-2, accompanied by cytochrome c release to the cytosol. In addition, GEI treatment resulted in a significant dose-dependent increase in caspase-3 and -9 proteolytic activities.

CONCLUSION

The present study demonstrates that the ability of GEI to induce apoptosis against HepG2 cells mediated by mitochondrial-mediated pathway.

Kruppel-like factor 2 inhibit the angiogenesis of cultured human liver sinusoidal endothelial cells through the ERK1/2 signaling pathway

Kruppel-like factor 2 (KLF2) is a crucial anti-angiogenic factor. However, its precise role in hepatic angiogenesis induced by liver sinusoidal endothelial cells (LSECs) remain unclear. This study was aimed to evaluate the effect of KLF2 on angiogenesis of LSECs and to explore the corresponding mechanism. Cultured human LSECs were infected with different lentiviruses to overexpress or suppress KLF2 expression. The CCK-8 assay, transwell migration assay and tube formation test, were used to investigate the roles of KLF2 in the proliferation, migration and vessel tube formation of LSECs, respectively. The expression and phosphorylation of ERK1/2 were detected by western blot. We discovered that the up-regulation of KLF2 expression dramatically inhibited proliferation, migration and tube formation in treated LSECs. Correspondingly, down-regulation of KLF2 expression significantly promoted proliferation, migration and tube formation in treated LSECs. Additionally, KLF2 inhibited the phosphorylation of ERK1/2 pathway, followed by the function of KLF2 in the angiogenesis of LSECs disrupted. In conclusion, KLF2 suppressed the angiogenesis of LSECs through inhibition of cell proliferation, migration, and vessel tube formation. These functions of KLF2 may be mediated through the ERK1/2 signaling pathway.

Anti-cancer effects of enteric-coated polymers containing mistletoe lectin in murine melanoma cells in vitro and in vivo

In this study, we evaluated the effects of Korean mistletoe (Viscum album L. var. coloratum) coated with a biodegradable polymer (Eudragit(®)) wall on the growth of mouse melanoma in vivo. Oral administration of 4% (430 mg/kg/day) enteric-coated mistletoe resulted in a significant reduction in tumor volume on day 14 compared to the negative control group in B16F10 melanoma-inoculated BDF1 mice. When we measured the survival rate, enteric-coated mistletoe-received mice had a higher survival rate after day 12. Also, we investigated the mechanism involving the cancer cell growth inhibition when melanoma cells were treated with Korean mistletoe lectin (Viscum album L. var. coloratum agglutinin, VCA) and its extract in vitro. As a result, a significant G0/G1 arrest was observed in both B16BL6 and B16F10 melanoma cells with VCA or mistletoe extract. In addition, VCA or mistletoe extract induced an increase in both early and late apoptosis in cells. When we studied the molecular mechanism, our results showed that VCA and mistletoe extract can increase activated multiple caspases (caspase-1, 3, 4, 5, 6, 7, 8, and 9), dose-dependently. We also found out that VCA and mistletoe treatment causes a significant decrease in the expression of procaspase-3 and 8.

Anti-proliferative and pro-apoptotic activities of Alpinia oxyphylla on HepG2 cells through ROS-mediated signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Fructus Alpiniae oxyphyllae (A. oxyphylla) is a traditional herb which is widely used in East Asian for the treatment of dyspepsia, diarrhea, abdominal pain, poor memory, inflammatory conditions and cancer.

MATERIALS AND METHODS

The cytotoxic activities of ethanol extract (EE) and five extract layers including petroleum ether (PE), dichloromethane (DCLM), acetoacetate (EtOAc), n-Butanol (n-Bu) and water fractions (WF) of A. oxyphylla were tested on HepG2, SW480, MCF-7, K562 and HUVEC cell lines using MTT assay and LDH release assay. The component analysis was performed on HPLC with gradient elution. Hoechst 33342 staining, DCFH-DA fluorescence microscopy, flow cytometry analysis, western blot and migration assays were carried out to determine the anti-cancer mechanisms of PE.

RESULTS

MTT analysis showed that EE, PE and DCLM could inhibit cell proliferation on HepG2, SW480, MCF-7, K562 and HUVEC cell lines, especially PE fraction. HPLC analysis pointed out five main components which may contribute to the anti-proliferative activity of PE. Further study showed that PE increased LDH release, induced apoptosis, disrupted mitochondrial membrane potential and elevated intracellular reactive oxygen species (ROS) in HepG2 cells, whereas the antioxidant N-acetyl-l-cysteine (NAC) prevented PE-induced ROS generation. The results of western blot revealed that PE induced apoptosis in HepG2 cells by enhancing Bax/Bcl-2 ratio, increasing cytochrome c in cytosol and activating caspase-3/9. Meanwhile, high levels of ROS could induce DNA damage-mediated protein expression, AKT, ERK inactivation and SAPKs activation. Furthermore, PE conspicuously blocked the migration of HUVEC cells.

CONCLUSION

The present results demonstrated that PE induced apoptosis in HepG2 cells may be via a ROS-mediated signaling pathway.