A Natural Product from Polygonum cuspidatum Sieb. Et Zucc. Promotes Tat-Dependent HIV Latency Reversal through Triggering P-TEFb's Release from 7SK snRNP

Advances for pharmacological activities of Polygonum cuspidatum - A review

CONTEXT

Polygonum cuspidatum Sieb. et Zucc (Polygonaceae), the root of which is included in the Chinese Pharmcopoeia under the name 'Huzhang', has a long history as a medicinal plant and vegetable. Polygonum cuspidatum has been used in traditional Chinese medicine for the treatment of inflammation, hyperlipemia, etc.

OBJECTIVE

This article reviews the pharmacological action and the clinical applications of Polygonum cuspidatum and its extracts, whether in vivo or in vitro. We also summarized the main phytochemical constituents and pharmacokinetics of Polygonum cuspidatum and its extracts.

METHODS

The data were retrieved from major medical databases, such as CNKI, PubMed, and SinoMed, from 2014 to 2022. Polygonum cuspidatum, pharmacology, toxicity, clinical application, and pharmacokinetics were used as keywords.

RESULTS

The rhizomes, leaves, and flowers of Polygonum cuspidatum have different phytochemical constituents. The plant contains flavonoids, anthraquinones, and stilbenes. Polygonum cuspidatum and the extracts have anti-inflammatory, antioxidation, anticancer, heart protection, and other pharmacological effects. It is used in the clinics to treat dizziness, headaches, traumatic injuries, and water and fire burns.

CONCLUSIONS

Polygonum cuspidatum has the potential to treat many diseases, such as arthritis, ulcerative colitis, asthma, and cardiac hypertrophy. It has a broad range of medicinal applications, but mainly focused on root medication; its aerial parts should receive more attention. Pharmacokinetics also need to be further investigated.

Luteolin Isolated from Polygonum cuspidatum Is a Potential Compound against Nasopharyngeal Carcinoma

Introduction

To reveal the mechanisms by which luteolin, the major bioactive component of the Traditional Chinese Medicine (TCM) Polygonum cuspidatum, inhibits proliferation and promotes apoptosis in nasopharyngeal carcinoma (NPC) CNE2 cells.

Methods

Based on the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP), bioactive compounds of P. cuspidatum, potential target genes and NPC disease targets of TCMSP were screened, relationship networks were constructed using these potential targets of NPC, and Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed. The predicted compounds, targets and pathways were corroborated using in vitro experiments, such as MTT, Cytation™ 5 real-time cell monitoring, cell cycle detection, Annexin V-FITC/PI double staining, Hoechst 33342 staining, and mitochondrial membrane potential (ΔΨm) detection.

Results

The results showed that 10 bioactive compounds (OB ≥30% and DL ≥0.18), 157 potential target genes from P. cuspidatum, and 56 common targets related to NPC were found. These included important bioactive compounds such as luteolin, quercetin, and beta-sitosterol. Key common targets included EGFR, MYC, AKT1, CASP3, CCND1, ERBB2, and common targets were enriched for the PI3K-AKT, JAK/STAT, MAPK, and C-type lectin receptor signaling pathways. The binding energy of luteolin for six common targets was less than -5.0 kcal·mol^-1. After luteolin (20 μM, and 40 μM) treatment to CNE2 cells for 36 h, cell survival rates decreased, accompanied by cell morphology changes, inhibition of the cell cycle at G2/M phase, and an induction of apoptosis. The expression of the cell proliferation related protein PCNA, the antiapoptosis protein XIAP, and the PI3K-AKT pathway diagram related proteins p-ERK1/2, ERK1/2, AKT, and PI3K, all decreased.

Conclusion

Luteolin derived from P. cuspidatum inhibited the proliferation of NPC CNE2 cells and promoted cell apoptosis through the PI3K-AKT signal pathway.

The Invasive Species Reynoutria japonica Houtt. as a Promising Natural Agent for Cardiovascular and Digestive System Illness

Polygoni Cuspidati Rhizoma et Radix, the dry roots and stems of Reynoutria japonica Houtt (called Huzhang, HZ in Chinese), is a traditional and popular chinese medicinal herb for thousands of years. As a widely used ethnomedicine in Asia including China, Japan, and Korea, HZ can invigorate the blood, cool heat, and resolve toxicity, which is commonly used in the treatment of favus, jaundice, scald, and constipation. However, HZ is now considered an invasive plant in the United States and many European countries. Therefore, in order to take advantage of HZ and solve the problem of biological invasion, scholars around the world have carried out abundant research studies on HZ. Until now, about 110 compounds have been isolated and identified from HZ, in which anthraquinones, stilbenes, and flavonoids would be the main bioactive ingredients for its pharmacological properties, such as microcirculation improvement, myocardial protective effects, endocrine regulation, anti-atherosclerotic activity, anti-oxidant activity, anti-tumor activity, anti-viral activity, and treatment of skin inflammation, burns, and scalds. HZ has a variety of active ingredients and broad pharmacological activities. It is widely used in health products, cosmetics, and even animal husbandry feed and has no obvious toxicity. Efforts should be made to develop more products such as effective drugs, health care products, cosmetics, and agricultural and animal husbandry products to benefit mankind.

Polyphenol Extracts from Grape Seeds and Apple Can Reactivate Latent HIV-1 Transcription through Promoting P-TEFb Release from 7SK snRNP

The principal barrier for the eradication of HIV/AIDS is the virus latency. One of the effective strategies so called “shock and kill” is to use latency-reversing agents (LRAs) to activate the latent HIV reservoirs and then combine them with the highly active antiretroviral therapy (HAART) to eradicate the virus. However, most of the current LRAs are too toxic; therefore, they have not been used clinically. Our preliminary data indicated that polyphenols from grape seeds can activate HIV in latently infected Jurkat T cells. Owing to a lot of food containing polyphenols and based on a reasoning whether all of these kinds of polyphenols contain the latency-reversing function, in this study, we screened 22 fruits/vegetables to see whether polyphenols from these can reactivate latent HIV-1 transcription. We finally proved that the polyphenols from grape seeds, apple, pomegranate, and bilberry can reactivate latent HIV-1 transcription. The activation of which can be detected on the level of protein and mRNA. The activation of which is in a dose- and time-dependent manner, while the activated polyphenol extracts have the effects to stimulate Tat-independent HIV-1 transcription. The mechanism shows that polyphenol extracts from grape seeds and apple can stimulate P-TEFb's release from 7SK snRNP to induce HIV gene transcription. These results indicate that using a few food of high-content polyphenols as latent activators and combining HARRT may be of great use for the treatment of HIV/AIDS in the future.

A natural product targets BRD4 to inhibit phase separation and gene transcription

The BET-bromodomain protein BRD4 uses two bromodomains to target acetyl-histones and other domains to recruit P-TEFb and other transcription factors to stimulate transcription of proto-oncogenes and key cell identity genes. Recent studies show that its ability to form phase-separated condensates that cluster preferentially at the super-enhancer regions of target genes is key for BRD4 to exert its functions. Here, we describe the identification of a natural product called PCG from polygonum cuspidatum Sieb.et Zucc., a traditional Chinese medicinal herb, that directly binds to BRD4. This binding inhibits BRD4 phase separation, turns dynamic BRD4 nuclear condensates into static aggregates, and effectively shuts down transcription of BRD4-dependent genes. Thus, through PCG we have discovered a BET inhibitor that not only selectively targets BRD4 but also works by suppressing phase separation, a mechanism of action that is different from those of the other known BET inhibitors.

Resveratrol Promotes HIV-1 Tat Accumulation via AKT/FOXO1 Signaling Axis and Potentiates Vorinostat to Antagonize HIV-1 Latency

BACKGROUND

The latent reservoir of HIV-1 is a major barrier to achieving the eradication of HIV-1/AIDS. One strategy is termed "shock and kill", which aims to awaken the latent HIV-1 using latency reversing agents (LRAs) to replicate and produce HIV-1 particles. Subsequently, the host cells containing HIV-1 can be recognized and eliminated by the immune response and anti-retroviral therapy. Although many LRAs have been found and tested, their clinical trials were dissatisfactory.

OBJECTIVE

To aim of the study was to investigate how resveratrol reactivates silent HIV-1 transcription and assess if resveratrol could be a candidate drug for the "shock" phase in "shock and kill" strategy.

METHODS

We used established HIV-1 transcription cell models (HeLa-based NH1 and NH2 cells) and HIV-1 latent cell models (J-Lat A72 and Jurkat 2D10 cells). We performed resveratrol treatment on these cell lines and studied the mechanism of how resveratrol stimulates HIV-1 gene transcription. We also tested resveratrol's bioactivity on primary cells isolated from HIV-1 latent infected patients.

RESULTS

Resveratrol promoted HIV-1 Tat protein levels, and resveratrol-induced Tat promotion was found to be dependent on the AKT/FOXO1 signaling axis. Resveratrol could partially dissociate P-TEFb (Positive Transcription Elongation Factor b) from 7SK snRNP (7SK small nuclear Ribonucleoprotein) and promote Tat-SEC (Super Elongation Complex) interaction. Preclinical studies showed that resveratrol potentiated Vorinostat to awaken HIV-1 latency in HIV-1 latent infected cells isolated from patients.

CONCLUSION

We found a new mechanism of resveratrol stimulating the production of HIV-1. Resveratrol could be a promising candidate drug to eradicate HIV-1 reservoirs.

Natural Products and HIV/AIDS

The study of natural products in biomedical research is not a modern concept. Many of the most successful medical therapeutics are derived from natural products, including those studied in the field of HIV/AIDS. Biomedical research has a rich history of discovery based on screens of medicinal herbs and traditional medicine practices. Compounds derived from natural products, which repress HIV and those that activate latent HIV, have been reported. It is important to remember the tradition in medical research to derive therapies based on these natural products and to overcome the negative perception of natural products as an "alternative medicine."

A chalcone derivative reactivates latent HIV-1 transcription through activating P-TEFb and promoting Tat-SEC interaction on viral promoter

The principal barrier to the eradication of HIV/AIDS is the existence of latent viral reservoirs. One strategy to overcome this barrier is to use latency-reversing agents (LRAs) to reactivate the latent proviruses, which can then be eliminated by effective anti-retroviral therapy. Although a number of LRAs have been found to reactivate latent HIV, they have not been used clinically due to high toxicity and poor efficacy. In this study, we report the identification of a chalcone analogue called Amt-87 that can significantly reactivate the transcription of latent HIV provirses and act synergistically with known LRAs such as prostratin and JQ1 to reverse latency. Amt-87 works by activating the human transcriptional elongation factor P-TEFb, a CDK9-cyclin T1 heterodimer that is part of the super elongation complex (SEC) used by the viral encoded Tat protein to activate HIV transcription. Amt-87 does so by promoting the phosphorylation of CDK9 at the T-loop, liberating P-TEFb from the inactive 7SK snRNP, and inducing the formation of the Tat-SEC complex at the viral promoter. Together, our data reveal chalcones as a promising category of compounds that should be further explored to identify effective LRAs for targeted reversal of HIV latency.

Reactivation of HIV-1 from Latency by an Ingenol Derivative from Euphorbia Kansui

Cells harboring latent HIV-1 pose a major obstacle to eradication of the virus. The ‘shock and kill’ strategy has been broadly explored to purge the latent reservoir; however, none of the current latency-reversing agents (LRAs) can safely and effectively activate the latent virus in patients. In this study, we report an ingenol derivative called EK-16A, isolated from the traditional Chinese medicinal herb Euphorbia kansui, which displays great potential in reactivating latent HIV-1. A comparison of the doses used to measure the potency indicated EK-16A to be 200-fold more potent than prostratin in reactivating HIV-1 from latently infected cell lines. EK-16A also outperformed prostratin in ex vivo studies on cells from HIV-1-infected individuals, while maintaining minimal cytotoxicity effects on cell viability and T cell activation. Furthermore, EK-16A exhibited synergy with other LRAs in reactivating latent HIV-1. Mechanistic studies indicated EK-16A to be a PKCγ activator, which promoted both HIV-1 transcription initiation by NF-κB and elongation by P-TEFb signal pathways. Further investigations aimed to add this compound to the therapeutic arsenal for HIV-1 eradication are in the pipeline.

The therapeutic landscape of HIV-1 via genome editing

Current treatment for HIV-1 largely relies on chemotherapy through the administration of antiretroviral drugs. While the search for anti-HIV-1 vaccine remain elusive, the use of highly active antiretroviral therapies (HAART) have been far-reaching and has changed HIV-1 into a manageable chronic infection. There is compelling evidence, including several side-effects of ARTs, suggesting that eradication of HIV-1 cannot depend solely on antiretrovirals. Gene therapy, an expanding treatment strategy, using RNA interference (RNAi) and programmable nucleases such as meganuclease, zinc finger nuclease (ZFN), transcription activator-like effector nuclease (TALEN), and clustered regularly interspaced short palindromic repeats/CRISPR-associated proteins (CRISPR-Cas9) are transforming the therapeutic landscape of HIV-1. TALENS and ZFNS are structurally similar modular systems, which consist of a FokI endonuclease fused to custom-designed effector proteins but have been largely limited, particularly ZFNs, due to their complexity and cost of protein engineering. However, the newly developed CRISPR-Cas9 system, consists of a single guide RNA (sgRNA), which directs a Cas9 endonuclease to complementary target sites, and serves as a superior alternative to the previous protein-based systems. The techniques have been successfully applied to the development of better HIV-1 models, generation of protective mutations in endogenous/host cells, disruption of HIV-1 genomes and even reactivating latent viruses for better detection and clearance by host immune response. Here, we focus on gene editing-based HIV-1 treatment and research in addition to providing  perspectives for refining these techniques.

Resveratrol Reactivates Latent HIV through Increasing Histone Acetylation and Activating Heat Shock Factor 1

The persistence of latent HIV reservoirs presents a significant challenge to viral eradication. Effective latency reversing agents (LRAs) based on "shock and kill" strategy are urgently needed. The natural phytoalexin resveratrol has been demonstrated to enhance HIV gene expression, although its mechanism remains unclear. In this study, we demonstrated that resveratrol was able to reactivate latent HIV without global T cell activation in vitro. Mode of action studies showed resveratrol-mediated reactivation from latency did not involve the activation of silent mating type information regulation 2 homologue 1 (SIRT1), which belonged to class-3 histone deacetylase (HDAC). However, latent HIV was reactivated by resveratrol mediated through increasing histone acetylation and activation of heat shock factor 1 (HSF1). Additionally, synergistic activation of the latent HIV reservoirs was observed under cotreatment with resveratrol and conventional LRAs. Collectively, this research reveals that resveratrol is a natural LRA and shows promise for HIV therapy.

Euphorbia Kansui Reactivates Latent HIV

While highly active anti-retroviral therapy has greatly improved the lives of HIV infected individuals, these treatments are unable to eradicate the virus. Current approaches to reactivate the virus have been limited by toxicity, lack of an orally available therapy, and limited responses in primary CD4+ T cells and in clinical trials. The PKC agonist ingenol, purified from Euphorbia plants, is a potent T cell activator and reactivates latent HIV. Euphorbia kansui itself has been used for centuries in traditional Chinese medicine to treat ascites, fluid retention, and cancer. We demonstrate that an extract of this plant, Euphorbia kansui, is capable of recapitulating T cell activation induced by the purified ingenol. Indeed, Euphorbia kansui induced expression of the early T cell activation marker CD69 and P-TEFb in a dose-dependent manner. Furthermore, Euphorbia kansui reactivated latent HIV in a CD4+ T cell model of latency and in HIV+ HAART suppressed PBMC. When combined with the other latency reversing agents, the effective dose of Euphorbia kansui required to reactive HIV was reduced 10-fold and resulted in synergistic reactivation of latent HIV. We conclude that Euphorbia Euphorbia kansui reactivates latent HIV and activates CD4+ T cells. When used in combination with a latency reversing agent, the effective dose of Euphorbia kansui is reduced; which suggests its application as a combination strategy to reactivate latent HIV while limiting the toxicity due to global T cell activation. As a natural product, which has been used in traditional medicine for thousands of years, Euphorbia kansui is attractive as a potential treatment strategy, particularly in resource poor countries with limited treatment options. Further clinical testing will be required to determine its safety with current anti-retroviral therapies.

Targeting the latent reservoir to achieve functional HIV cure

While highly active anti-retroviral therapy has greatly improved the lives of HIV-infected individuals, current treatments are unable to completely eradicate the virus. This is due to the presence of HIV latently infected cells which harbor transcriptionally silent HIV. Latent HIV does not replicate or produce viral proteins, thereby preventing efficient targeting by anti-retroviral drugs. Strategies to target the HIV latent reservoir include viral reactivation, enhancing host defense mechanisms, keeping latent HIV silent, and using gene therapy techniques to knock out or reactivate latent HIV. While research into each of these areas has yielded promising results, currently no one mechanism eradicates latent HIV. Instead, combinations of these approaches should be considered for a potential HIV functional cure.