Wogonin induces apoptosis by suppressing E6 and E7 expressions and activating intrinsic signaling pathways in HPV-16 cervical cancer cells

In-silico study unveils potential phytocompounds in Andrographis paniculata against E6 protein of the high-risk HPV-16 subtype for cervical cancer therapy

Despite therapeutic advancements, cervical cancer caused by high-risk subtypes of the human papillomavirus (HPV) remains a leading cause of cancer-related deaths among women worldwide. This study aimed to discover potential drug candidates from the Asian medicinal plant Andrographis paniculata, demonstrating efficacy against the E6 protein of high-risk HPV-16 subtype through an in-silico computational approach. The 3D structures of 32 compounds (selected from 42) derived from A. paniculata, exhibiting higher binding affinity, were obtained from the PubChem database. These structures underwent subsequent analysis and screening based on criteria including binding energy, molecular docking, drug likeness and toxicity prediction using computational techniques. Considering the spectrometry, pharmacokinetic properties, docking results, drug likeliness, and toxicological effects, five compounds-stigmasterol, 1H-Indole-3-carboxylic acid, 5-methoxy-, methyl ester (AP7), andrographolide, apigenin and wogonin-were selected as the potential inhibitors against the E6 protein of HPV-16. We also performed 200 ns molecular dynamics simulations of the compounds to analyze their stability and interactions as protein-ligand complexes using imiquimod (CID-57469) as a control. Screened compounds showed favorable characteristics, including stable root mean square deviation values, minimal root mean square fluctuations and consistent radius of gyration values. Intermolecular interactions, such as hydrogen bonds and hydrophobic contacts, were sustained throughout the simulations. The compounds displayed potential affinity, as indicated by negative binding free energy values. Overall, findings of this study suggest that the selected compounds have the potential to act as inhibitors against the E6 protein of HPV-16, offering promising prospects for the treatment and management of CC.

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.

The role and mechanism of TCM in the prevention and treatment of infectious diseases

The constant presence of infectious diseases poses an everlasting threat to the entire world. In recent years, there has been an increased attention toward the application of traditional Chinese medicine (TCM) in the treatment of emerging infectious diseases, as it has played a significant role. The aim of this article is to provide a concise overview of the roles and mechanisms of TCM in treating infectious diseases. TCM possesses the ability to modulate relevant factors, impede signaling pathways, and inhibit microbial growth, thereby exhibiting potent antiviral, antibacterial, and anti-inflammatory effects that demonstrate remarkable efficacy against viral and bacterial infections. This article concludes that the comprehensive regulatory features of Chinese herbal medicines, with their various components, targets, and pathways, result in synergistic effects. The significance of Chinese herbal medicines in the context of infectious diseases should not be underestimated; however, it is crucial to also acknowledge their underutilization. This paper presents constructive suggestions regarding the challenges and opportunities faced by Chinese medicines. Particularly, it emphasizes the effectiveness and characteristics of Chinese medicines in the treatment of infectious diseases, specifying how these medicines' active substances can be utilized to target infectious diseases. This perspective is advantageous in facilitating researchers' pharmacological studies on Chinese medicines, focusing on the specific points of action. The mechanism of action of Chinese herbal medicines in the treatment of infectious diseases is comprehensively elucidated in this paper, providing compelling evidence for the superior treatment of infectious diseases through Chinese medicine. This information is favorable for advancing the development of TCM and its potential applications in the field of infectious diseases.

In silico and in vitro evaluation of antiviral activity of wogonin against main protease of porcine epidemic diarrhea virus

The high mortality rate of weaned piglets infected with porcine epidemic diarrhea virus (PEDV) poses a serious threat to the pig industry worldwide, demanding urgent research efforts related to developing effective antiviral drugs to prevent and treat PEDV infection. Small molecules can possibly prevent the spread of infection by targeting specific vital components of the pathogen’s genome. Main protease (Mpro, also named 3CL protease) plays essential roles in PEDV replication and has emerged as a promising target for the inhibition of PEDV. In this study, wogonin exhibited antiviral activity against a PEDV variant isolate, interacting with the PEDV particles and inhibiting the internalization, replication and release of PEDV. The molecular docking model indicated that wogonin was firmly embedded in the groove of the active pocket of Mpro. Furthermore, the interaction between wogonin and Mpro was validated in silico via microscale thermophoresis and surface plasmon resonance analyses. In addition, the results of a fluorescence resonance energy transfer (FRET) assay indicated that wogonin exerted an inhibitory effect on Mpro. These findings provide useful insights into the antiviral activities of wogonin, which could support future research into anti-PEDV drugs.`

Wogonin induces ferroptosis in pancreatic cancer cells by inhibiting the Nrf2/GPX4 axis

Pancreatic cancer is a common gastrointestinal tract malignancy. Currently, the therapeutic strategies for pancreatic cancers include surgery, radiotherapy, and chemotherapy; however, the surgical procedure is invasive, and the overall curative outcomes are poor. Furthermore, pancreatic cancers are usually asymptomatic during early stages and have a high degree of malignancy, along with a high rate of recurrence and metastasis, thereby increasing the risk of mortality. Studies have shown that ferroptosis regulates cell proliferation and tumour growth and reduces drug resistance. Hence, ferroptosis could play a role in preventing and treating cancers. Wogonin is a flavonoid with anticancer activity against various cancers, including pancreatic cancer. It is extracted from the root of Scutellaria baicalensis Georgi. In this study, we show that wogonin inhibits the survival and proliferation of human pancreatic cancer cell lines and induces cell death. We performed RNA-sequencing and analysed the differentially expressed gene and potential molecular mechanism to determine if wogonin reduced cell survival via ferroptosis. Our results showed that wogonin upregulates the levels of Fe²⁺, lipid peroxidation and superoxide and decreases the protein expression levels of ferroptosis suppressor genes, and downregulates level of glutathione in pancreatic cancer cells. In addition, ferroptosis inhibitors rescue the ferroptosis-related events induced by wogonin, thereby confirming the role of ferroptosis. A significant increase in ferroptosis-related events was observed after treatment with both wogonin and ferroptosis inducer. These results show that wogonin could significantly reduces pancreatic cancer cell proliferation and induce ferroptosis via the Nrf2/GPX4 axis. Therefore, wogonin could be potentially used for treating patients with pancreatic cancer.

Wogonin increases gemcitabine sensitivity in pancreatic cancer by inhibiting Akt pathway

Pancreatic cancer has a high degree of malignancy and a low 5-year survival rate, and drug resistance is one of the main factors leading to poor prognosis of pancreatic cancer. Wogonin is a flavonoid drug isolated from Scutellaria baicalensis, which has certain antitumor activity. Hence the purpose of this study was to investigate whether wogonin can be used to enhance the sensitivity of pancreatic cancer to gemcitabine chemotherapy, and investigate its possible sensitization mechanism. In vitro, MTT assay showed that wogonin increased gemcitabine cytotoxicity in gemcitabine-resistant pancreatic cancer cells. In vivo, Wogonin combined with gemcitabine was found to inhibit tumor growth in orthotopic pancreatic cancer mouse model. In order to explore the sensitization mechanism, the differentially expressed genes (DEGs) of the gemcitabine-resistant cell line Panc-1 and the gemcitabine-sensitive cell line Bxpc-3 were screened through the GEO database, and 15 differentially expressed genes were obtained by intersecting with the potential targets of wogonin. Gene Ontology and KEGG enrichment analysis was performed. Bioinformatics results predicted that wogonin promoted pancreatic cancer cell apoptosis by inhibiting protein kinase B (Akt) signaling, thereby enhancing the sensitivity of gemcitabine to Pancreatic cancer. The above results were also verified by flow cytometry and Western blotting experiments. In conclusion, wogonin may enhance the sensitivity of gemcitabine by inhibiting Akt pathway.

Therapeutic Effects of Natural Products on Cervical Cancer: Based on Inflammatory Pathways

Inflammation is a protective response of the body to an irritant. When an inflammatory response occurs, immune cells are recruited to the injury, eliminating the irritation. The excessive inflammatory response can cause harm to the organism. Inflammation has been found to contribute to cervical cancer if there is a problem with the regulation of inflammatory response. Cervical cancer is one of the most common malignant tumors globally, and the incidence tends to be younger. The harm of cervical cancer cannot be ignored. The standard treatments for cervical cancer include surgery, radiotherapy and chemotherapy. However, the prognosis for this treatment is poor, so it is urgent to find a safer and more effective treatment. Natural products are considered excellent candidates for the treatment of cervical cancer. In this review, we first describe the mechanisms by which inflammation induces cervical cancer. Subsequently, we highlight natural products that can treat cervical cancer through inflammatory pathways. We also introduce natural products for the treatment of cervical cancer in clinical trials. Finally, methods to improve the anticancer properties of natural products were added, and the development status of natural products was discussed.

Natural Bioactives: Back to the Future in the Fight against Human Papillomavirus? A Narrative Review

Human papillomavirus (HPV) still represents an important threat to health worldwide. Better therapy in terms of further improvement of outcomes and attenuation of related side-effects is desirable. The pharmaceutical industry has always targeted natural substances-phytochemicals in particular-to identify lead compounds to be clinically validated and industrially produced as antiviral and anticancer drugs. In the field of HPV, numerous naturally occurring bioactives and dietary phytochemicals have been investigated as potentially valuable in vitro and in vivo. Interference with several pathways and improvement of the efficacy of chemotherapeutic agents have been demonstrated. Notably, some clinical trials have been conducted. Despite being endowed with general safety, these natural substances are in urgent need of further assessment to foresee their clinical exploitation. This review summarizes the basic research efforts conducted so far in the study of anti-HPV properties of bio-actives with insights into their mechanisms of action and highlights the variety of their natural origin in order to provide comprehensive mapping throughout the different sources. The clinical studies available are reported, as well, to highlight the need of uniformity and consistency of studies in the future to select those natural compounds that may be suited to clinical application.

HPV-induced cancers: preclinical therapeutic advancements

INTRODUCTION

High-risk HPV infections are related to several epithelial cancers. Despite the availability of prophylactic vaccines, HPV infections are still responsible for about 5% of all human malignancies worldwide. While therapeutic vaccines are ongoing clinical trials, genotoxic agents and surgical interventions represent current clinical treatments, with no specific anti-HPV drugs yet available in the clinics.

AREAS COVERED

We offer a comprehensive report of small molecules in preclinical studies proposed as potential anticancer agents against HPV-driven tumors. Given the importance of HPV oncoproteins for cancer maintenance, particularly E6 and E7, we present a classification of both non-targeted and targeted agents, with a further subdivision of the latter into two categories according to their either direct or indirect activity against viral protein functions.

EXPERT OPINION

Prophylactic vaccines can prevent the insurgence of HPV-related cancers, but have no effect against pre-existing infections. Moreover, their high cost, genotype-restricted effect and the growing worldwide distrust for vaccines make the availability of a specific drug an unmet medical need. Different viral early proteins emerge as ideal candidates for drug development. We highlight the most promising strategies and address future challenges in this field to herald the prospect of a specific therapeutic regimen against HPV-related cancers.

Potential Mechanisms of Plant-Derived Natural Products in the Treatment of Cervical Cancer

Cervical cancer is the second most common gynecological malignancy globally; it seriously endangers women’s health because of its high morbidity and mortality. Conventional treatments are prone to drug resistance, recurrence and metastasis. Therefore, there is an urgent need to develop new drugs with high efficacy and low side effects to prevent and treat cervical cancer. In recent years, plant-derived natural products have been evaluated as potential anticancer drugs that preferentially kill tumor cells without severe adverse effects. A growing number of studies have shown that natural products can achieve practical anti-cervical-cancer effects through multiple mechanisms, including inhibition of tumor-cell proliferation, induction of apoptosis, suppression of angiogenesis and telomerase activity, enhancement of immunity and reversal of multidrug resistance. This paper reviews the therapeutic effects and mechanisms of plant-derived natural products on cervical cancer and provides references for developing anti-cervical-cancer drugs with high efficacy and low side effects.

Fascinating Chemopreventive Story of Wogonin: A Chance to Hit on the Head in Cancer Treatment

Cancer, global havoc, is a group of debilitating diseases that strikes family as well as society. Cancer cases are drastically increasing these days. Despite many therapies and surgical procedures available, cancer is still difficult to control due to limited effective therapies or targeted therapies. Natural products can produce lesser side effects to the normal cells, which are the major demerit of chemotherapies and radiation. Wogonin, a natural product extracted from the plant, Scutellaria baicalensis has been widely studied and found with a high caliber to tackle most of the cancers via several mechanisms that include intrinsic as well as extrinsic apoptosis signaling pathways, carcinogenesis diminution, telomerase activity inhibition, metastasis inhibition in the inflammatory microenvironment, anti-angiogenesis, cell growth inhibition and arrest of the cell cycle, increased generation of H₂O₂ and accumulation of Ca²⁺ and also as an adjuvant along with anticancer drugs. This article discusses the role of wogonin in various cancers, its synergism with various drugs, and the mechanism by which wogonin controls tumor growth.

Wogonoside promotes apoptosis and ER stress in human gastric cancer cells by regulating the IRE1α pathway

Gastric cancer is a disease that occurs in the digestive system of humans and remains a problem in the medical field. Wogonoside, a natural flavonoid, has been reported to exert antitumor effects on various types of tumors. However, the effects of wogonoside on gastric cancer remain elusive. The aim of the present study was to detect whether wogonoside treatment could induce apoptosis and ER stress in gastric cancer cells. In the present study, CCK-8 assay was used to detect the cell viability, Annexin V/PI staining was used to detect the cells apoptosis, western blot analysis and real-time PCR analysis was used to detect the endoplasmic reticulum (ER) stress in the AGS and MKN-45 gastric cancer cell lines. Wogonoside treatment reduced the viability of AGS and MKN-45 cells and induced apoptosis. Furthermore, the expression level of caspase-3 and -9 significantly increased following wogonoside treatment compared with that in non-treated cells, and the protein expression levels of proapoptotic Bax and antiapoptotic Bcl-2 increased and decreased, respectively compared with that in the control group. In addition, the phosphorylated protein expression levels of mitogen-activated protein kinase kinase 5 (ASK1) and JNK increased following wogonoside treatment, and the protein expression levels of tumor necrosis factor receptor-associated factor 2 (TRAF2) and serine/threonine-protein kinase/endoribonuclease IRE1 (IRE1α) were also increased following treatment with 50 µM wogonoside for 48 h. Furthermore, the interactions between IRE1α, TRAF2 and ASK1 significantly increased following wogonoside treatment, suggesting that wogonoside induced endoplasmic reticulum (ER) stress in the AGS and MKN-45 cell lines. In addition, small interfering RNA-mediated silencing of IRE1α suppressed the activity of the IRE1α-TRAF2-ASK1 complex and prevented wogonoside-induced cell apoptosis. In conclusion, the results of the present study suggested that wogonoside exhibited antitumor activity by inducing ER stress-associated cell death through the IRE1α-TRAF2-ASK1 pathway.

Flavonoids as Multi-Target Compounds: A Special Emphasis on their Potential as Chemo-adjuvants in Cancer Therapy

Flavonoids are low molecular weight, polyphenolic phytochemicals, obtained from secondary metabolism of various plant compounds. They have a spectrum of pharmacological efficacies, including potential anticancer efficacy. Natural flavonoids are present in fruits, vegetables, grains, bark, roots, stems, flowers, tea and wine. Flavonoids can attenuate or inhibit the initiation, promotion and progression of cancer by modulating various enzymes and receptors in diverse pathways that involve cellular proliferation, differentiation, apoptosis, inflammation, angiogenesis and metastasis. Furthermore, in vitro, flavonoids have been shown to reverse multidrug resistance when used as chemo-adjuvants. Flavonoids (both natural and synthetic analogues) interact with several oncogenic targets through dependent and independent mechanisms to mediate their anticancer efficacy in different types of cancer cells.

Potential therapeutic and pharmacological effects of Wogonin: an updated review

Flavonoids are members of polyphenolic compounds, which are naturally presented in fruits, vegetables, and some medicinal plants. Traditionally, the root of Scutellaria baicalensis is widely used as Chinese herbal medicine and contains several major bioactive compounds such as Wogonin, Scutellarein, Baicalein, and Baicalin. Experimental and clinical evidence has been proving that Wogonin exhibits diverse biological activities such as anti-cancer, anti-inflammation, and treatment of bacterial and viral infections. In this review, we summarize and emphasize the benefits of Wogonin as a therapeutic adjuvant for anti-viral infection, anti-inflammation, neuroprotection as well as anxiolytic and anticonvulsant. Moreover, the molecular mechanism(s) how Wogonin mediates the cellular signal pathways and immune responses are also discussed and highlighted valuable properties of Wogonin in multiple therapies.

Plant-Derived Natural Compounds in Genetic Vaccination and Therapy for HPV-Associated Cancers

Simple Summary

DNA vaccination represents a useful approach for human papillomavirus (HPV) cancer therapy. The therapeutic potential of plant-based natural compounds for control of HPV- associated cancers has been also widely explored. Genetic vaccines for HPV-associated tumors that include plant protein-encoding gene sequences, used alone or in combinations with plant metabolites, are being investigated but are still in their infancy. Main focus of this paper is to provide an overview of the current state of novel therapeutic strategies employing genetic vaccines along with plant-derived compounds and genes. We highlight the importance of multimodality treatment regimen such as combining immunotherapy with plant-derived agents.

Abstract

Antigen-specific immunotherapy and, in particular, DNA vaccination provides an established approach for tackling human papillomavirus (HPV) cancers at different stages. DNA vaccines are stable and have a cost-effective production. Their intrinsic low immunogenicity has been improved by several strategies with some success, including fusion of HPV antigens with plant gene sequences. Another approach for the control of HPV cancers is the use of natural immunomodulatory agents like those derived from plants, that are able to interfere in carcinogenesis by modulating many different cellular pathways and, in some instances, to reduce chemo- and radiotherapy resistance of tumors. Indeed, plant-derived compounds represent, in many cases, an abundantly available, cost-effective source of molecules that can be either harvested directly in nature or obtained from plant cell cultures. In this review, an overview of the most relevant data reported in literature on the use of plant natural compounds and genetic vaccines that include plant-derived sequences against HPV tumors is provided. The purpose is also to highlight the still under-explored potential of multimodal treatments implying DNA vaccination along with plant-derived agents.

Can network pharmacology identify the anti-virus and anti- inflammatory activities of Shuanghuanglian oral liquid used in Chinese medicine for respiratory tract infection?

Introduction

Shuanghuanglian (SHL) oral liquid is a well-known traditional Chinese medicine preparation administered for respiratory tract infections in China. However, the underlying pharmacological mechanisms remain unclear. The present study aims to determine the potential pharmacological mechanisms of SHL oral liquid based on network pharmacology.

Methods

A network pharmacology-based strategy including collection and analysis of putative compounds and target genes, network construction, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and Gene Ontology (GO) enrichment, identification of key compounds and target genes, and molecule docking was performed in this study.

Results

A total of 82 bioactive compounds and 226 putative target genes of SHL oral liquid were collected. Of note, 28 hub target genes including 4 major hub target genes: estrogen receptor 1 (ESR1), nuclear receptor coactivator 2 (NCOA2), nuclear receptor coactivator 1 (NCOA1), androgen receptor (AR) and 5 key compounds (quercetin, luteolin, baicalein, kaempferol and wogonin) were identified based on network analysis. The hub target genes mainly enriched in pathways including PI3K-Akt signaling pathway, human cytomegalovirus infection, and human papillomavirus infection, which could be the underlying pharmacological mechanisms of SHL oral liquid for treating diseases. Moreover, the key compounds had great molecule docking binding affinity with the major hub target genes.

Conclusion

Using network pharmacology analysis, SHL oral liquid was found to contain anti-virus, anti-inflammatory, and “multi-compounds and multi-targets” with therapeutic actions. These findings may provide a valuable direction for further clinical application and research.

Human Papillomavirus E6 and E7: The Cervical Cancer Hallmarks and Targets for Therapy

Human papillomavirus (HPV)-induced cervical cancer is a major health issue among women from the poorly/under-developed sectors of the world. It accounts for a high-mortality rate because of its late diagnosis and poor prognosis. Initial establishment and subsequent progression of this form of cancer are completely dependent on two major oncogenes E6 and E7, which are expressed constitutively leading to tumorigenesis. Thus, manipulation of these genes represents the most successful form of cervical cancer therapy. In the present article, information on structural, functional, and clinical dimensions of E6 and E7 activity has been reviewed. The genome organization and protein structure of E6 and E7 have been discussed followed by their mechanism to establish the six major cancer hallmarks in cervical tissues for tumor propagation. The later section of this review article deals with the different modes of therapeutics, which functions by deregulating E6 and E7 activity. Since E6 and E7 are the biomarkers of a cervical cancer cell and are the ones driving the cancer progression, therapeutic approaches targeting E6 and E7 have been proved to be highly efficient in terms of focused removal of abnormally propagating malignant cells. Therapeutics including different forms of vaccines to advanced genome editing techniques, which suppress E6 and E7 activity, have been found to successfully bring down the population of cervical cancer cells infected with HPV. T-cell mediated immunotherapy is another upcoming successful form of treatment to eradicate HPV-infected tumorigenic cells. Additionally, therapeutics using natural compounds from plants or other natural repositories, i.e., phytotherapeutic approaches have also been reviewed here, which prove their anticancer potential through E6 and E7 inhibitory effects. Thus, E6 and E7 repression through any of these methods is a significant approach toward cervical cancer therapy, described in details in this review along with an insight into the signaling pathways and molecular mechanistic of E6 and E7 action.

Identification of potential binding pocket on viral oncoprotein HPV16 E6: a promising anti-cancer target for small molecule drug discovery

BACKGROUND

Several human cancers, especially cervical cancer are caused by the infection of high risk strains of human papillomaviruses (HPV), notably HPV16. It is implicated that the oncoprotein E6 expressed from HPV, is inhibiting the apoptotic pathway by binding to adaptor molecule FADD (Fas-associated death domain). Inhibiting E6 interactions with FADD could provide a promising treatment for cervical cancer. There are few small molecules reported to inhibit such interactions. However, the FADD binding site information on the HPV E6 is not currently available. This binding site information may provide an opportunity to design new small molecule inhibitors to treat E6 mediated cancers. In this study we report the possible binding pocket on HPV16 E6 oncoprotein by using activity data of reported inhibitors through a stepwise molecular modeling approach.

RESULTS

Blind docking and removing duplicates followed by visual inspection to determine ligand-receptor interactions provided 68 possible binding sites on the E6 protein. Individual docking of all known inhibitors lead to the identification of 28 pockets having some kind of correlation with their activity data. It was also observed that several of these pockets overlapped with each other, having some amino acids in common. Amino acids Leu50 and Cys51 were identified as key E6 residues for high affinity ligand binding which are seen in most of these pockets. In most cases, ligands demonstrated a hydrogen bond interaction with Cys51. Ala61, Arg131 and Gln107 were also frequently observed showing interactions among these pockets. A few amino acids unique to each ligand were also identified representing additional interactions at the receptor site.

CONCLUSIONS

After determining receptor-ligand interactions between E6 oncoprotein and the six known inhibitors, the amino acids Cys51, Leu50, Arg102, Arg131, Leu67, Val62, and Gln107 were identified to have importance in E6 inhibition. It was generally observed that Leu50 and Cys51 are necessary for high binding affinity with Cys51 being essential for hydrogen bonding. This study identified a potential binding pocket for the E6 inhibitors. Identification of the ligand binding pocket helps to design novel inhibitors of HPV16 E6 oncoprotein as a promising treatment for cervical cancer.

Deglycosylation of wogonoside enhances its anticancer potential

Introduction

Scutellaria baicalensis is commonly used in Asia as an herbal medicine to treat a variety of ailments, including cancer. Wogonoside, one major constituent of S. baicalensis, can be primarily converted to wogonin through deglycosylation via enteric microbiome metabolism.

Materials and Methods

The antiproliferative effects of the glycoside (wogonoside) and its deglycosylated compound (wogonin) on a panel of human cancer cell lines from the most common solid tumors were evaluated using the MTS colorimetric assay. Cell cycle and apoptosis were determined using flow cytometry. Enzymatic activities of caspases were measured, and the interactions of wogonin and caspases were explored by a docking analysis.

Results

Wogonoside did not have obvious antiproliferative effects on the cancer cells. In contrast, wogonin showed significant antiproliferative activities on all the tested cancer cells. Wogonin arrested the cells in the G1 phase and significantly induced cell apoptosis. The compound also activated the expression of caspases 3 and 9. The docking results suggest that the compound forms hydrogen bonds with Phe250 and Ser251, and π-π interactions with Phe256 in caspase 3, and with Asp228 in caspase 9.

Conclusions

After wogonoside deglycosylation, wogonin significantly enhanced its anticancer potential as a potent anticancer compound derived from S. baicalensis.

Scutellaria: Debates on the anticancer property

The widespread use of plants as accessible anticancer agents leads to the identification of many natural source chemotherapeutic agents. Scutellaria one of the popular genus of flowering plants has been used for various human illnesses for thousands of years. Scutellaria has anti-metastatic, anti-proliferative, anti-invasion, anti-angiogenic and apoptosis effects in vitro as well as in vivo. Despite numerous reports on the cytotoxic-antitumor activity of the plant, there are still some issues need further consideration. Issues such as unjustified interpretations, lack of attention to the pharmacokinetics profile and weak study design may affect the final decision about the use of plants as anticancer agents and possibly needs reconsideration. In this review, we have summarized the potential health benefits of Scutellaria and its active components also the underlying mechanism of cytotoxicity and antitumor activity. Meanwhile we have discussed concerns may interfere with the precise conclusion.

Synthetic siRNA targeting human papillomavirus 16 E6: a perspective on in vitro nanotherapeutic approaches

High-risk human papillomaviruses infect skin and mucosa, causing approximately 5% of cancers worldwide. In the search for targeted nanotherapeutic approaches, siRNAs against the viral E6 transcript have been molecules of interest but have not yet seen successful translation into the clinic. By reviewing the past approximately 15 years of in vitro literature, we identify the need for siRNA validation protocols which concurrently evaluate ranges of key treatment parameters as well as characterize downstream process restoration in a methodical, quantitative manner and demonstrate their implementation using our own data. We also reflect on the future need for more appropriate cell culture models to represent patient lesions as well as the application of personalized approaches to identify optimal treatment strategies.

TLR4-MyD88-TRAF6-TAK1 Complex-Mediated NF-κB Activation Contribute to the Anti-Inflammatory Effect of V8 in LPS-Induced Human Cervical Cancer SiHa Cells

The synthetic compound 7-4-[Bis-(2-hydroxyethyl)-amino]-butoxy-5-hydroxy-8-methoxy-2-phenylchromen-4-one (V8) is a novel flavonoid-derived compound. In this study, we investigated the effects of V8 on Toll-like receptor 4 (TLR4)-mediated inflammatory reaction in human cervical cancer SiHa cells and lipopolysaccharide (LPS)-induced TLR4 activity in cervical cancer SiHa (HPV16+) cells, but not in HeLa (HPV18+) and C33A (HPV-) cells. In addition, V8 inhibited LPS-induced expression of TLR4, MyD88, TRAF6 and phosphorylation of TAK1, and their interaction with TLR4 in SiHa cells, resulting in an inhibition of TLR4-MyD88-TRAF6-TAK1 complex. Moreover, V8 blocked LPS-induced phosphorylation of IκB and IKK, resulting in inhibition of the nuclear translocation of P65-NF-κB in SiHa cells. We also found that V8 reduced the expression of NF-κB target genes, such as those for COX-2, iNOS, IL-6, IL-8, CCL-2, and TNF-α in LPS-stimulated SiHa cells. These results suggested that V8 exerted an anti-inflammatory effect on SiHa cells by inhibiting the TLR4-MyD88-TRAF6-TAK1 complex-mediated NF-κB activation.

Transforming properties of Felis catus papillomavirus type 2 E6 and E7 putative oncogenes in vitro and their transcriptional activity in feline squamous cell carcinoma in vivo

Felis catus papillomavirus type 2 (FcaPV2) DNA is found in feline cutaneous squamous cell carcinomas (SCCs); however, its biological properties are still uncharacterized. In this study, we successfully expressed FcaPV2 E6 and E7 putative oncogenes in feline epithelial cells and demonstrated that FcaPV2 E6 binds to p53, impairing its protein level. In addition, E6 and E7 inhibited ultraviolet B (UVB)-triggered accumulation of p53, p21 and pro-apoptotic markers such as Cleaved Caspase3, Bax and Bak, suggesting a synergistic action of the virus with UV exposure in tumour pathogenesis. Furthermore, FcaPV2 E7 bound to feline pRb and impaired pRb levels, resulting in upregulation of the downstream pro-proliferative genes Cyclin A and Cdc2. Importantly, we demonstrated mRNA expression of FcaPV2 E2, E6 and E7 in feline SCC samples, strengthening the hypothesis of a causative role in the development of feline SCC.

Advances of wogonin, an extract from Scutellaria baicalensis, for the treatment of multiple tumors

As the major bioactive compound of Scutellaria baicalensis that has been approved to be effective as an anti-inflammatory and antiviral inhibitor in cardiovascular diseases, wogonin (WG) showed potent and promising antitumor effects both in vitro and in vivo. It has been proved that WG has the ability to inhibit the growth of tumor cells, induce apoptosis, and suppress angiogenesis. The molecular mechanisms involve reactive oxygen species, Ca²⁺, NF-κB, tumor necrosis factor-related apoptosis-inducing ligand, and tumor necrosis factor-alpha. Furthermore, the synergistic effect of WG with 5-fluorouracil, etoposide, and adriamycin to enhance chemotherapy and reverse drug resistance has also been confirmed. In this review, we summarize the advances in recent years on the antitumor effect of WG on multiple tumors; in addition, we also present information regarding the synergistic and chemosensitizing effects of WG with other drugs to illustrate its potential use in the clinic.

Cudrania tricuspidata Stem Extract Induces Apoptosis via the Extrinsic Pathway in SiHa Cervical Cancer Cells

The focus of this study is the anti-cancer effects of Cudrania tricuspidata stem (CTS) extract on cervical cancer cells. The effect of CTS on cell viability was investigated in HPV-positive cervical cancer cells and HaCaT human normal keratinocytes. CTS showed significant dose-dependent cytotoxic effects in cervical cancer cells. However, there was no cytotoxic effect of CTS on HaCaT keratinocytes at concentrations of 0.125-0.5 mg/mL. Based on this cytotoxic effect, we demonstrated that CTS induced apoptosis by down-regulating the E6 and E7 viral oncogenes. Apoptosis was detected by DAPI staining, annexin V-FITC/PI staining, cell cycle analysis, western blotting, RT-PCR, and JC-1 staining in SiHa cervical cancer cells. The mRNA expression levels of extrinsic pathway molecules such as Fas, death receptor 5 (DR5), and TNF-related apoptosis-inducing ligand (TRAIL) were increased by CTS. Furthermore, CTS treatment activated caspase-3/caspase-8 and cleavage of poly (ADP-ribose) polymerase (PARP). However, the mitochondrial membrane potential and expression levels of intrinsic pathway molecules such as Bcl-2, Bcl-xL, Bax, and cytochrome C were not modulated by CTS. Taken together, these results indicate that CTS induced apoptosis by activating the extrinsic pathway, but not the intrinsic pathway, in SiHa cervical cancer cells. These results suggest that CTS can be used as a modulating agent in cervical cancer.

Characteristic features of cytotoxic activity of flavonoids on human cervical cancer cells

Cervical cancer is the most common gynecologic malignancy worldwide and development of new therapeutic strategies and anticancer agents is an urgent priority. Plants have remained an important source in the search for novel cytotoxic compounds and several polyphenolic flavonoids possess antitumor properties. In this review article, data about potential anticarcinogenic activity of common natural flavonoids on various human cervical cancer cell lines are compiled and analyzed showing perspectives for the use of these secondary metabolites in the treatment of cervical carcinoma as well as in the development of novel chemotherapeutic drugs. Such anticancer effects of flavonoids seem to differentially depend on the cellular type and origin of cervical carcinoma creating possibilities for specific targeting in the future. Besides the cytotoxic activity per se, several flavonoids can also contribute to the increase in efficacy of conventional therapies rendering tumor cells more sensitive to standard chemotherapeutics and irradiation. Although the current knowledge is still rather scarce and further studies are certainly needed, it is clear that natural flavonoids may have a great potential to benefit cervical cancer patients.

N-Benzylcinnamide induces apoptosis in HPV16 and HPV18 cervical cancer cells via suppression of E6 and E7 protein expression

Seventy percent of all cervical cancers are caused by human papillomavirus (HPV) infections. Natural products are being extensively explored for their potential ability to prevent and treat cervical cancers. N-benzylcinnamide (PT-3) is a natural product purified from Piper submultinerve. Whether or not PT-3 has an effect on cervical cancer cells is as yet unknown. Therefore, we set out to explore the mechanism of action behind PT-3 and how it affects cells that either contain or lack HPV DNA. Our results demonstrate that PT-3 slows the growth kinetics of CaSki (HPV-16 positive) and HeLa (HPV-18 positive) cells in a dose-dependent manner, but does not slows HPV-negative cells. Importantly, we also found that PT-3 induces apoptosis by suppressing expression of E6 and E7 viral oncogenes in HPV-infected cervical cancer CaSki and HeLa cells. Moreover, we found that suppression of E6 and E7 expression leads to modulations in p53 and protein retinoblastomas, which are not changed in HPV-negative cervical cancer C33A cells. These findings demonstrate that PT-3 can effectively promote apoptosis by downregulating expression of E6 and E7.

Curcumin improves the paclitaxel-induced apoptosis of HPV-positive human cervical cancer cells via the NF-κB-p53-caspase-3 pathway

Paclitaxel, isolated from Taxus brevifolia, is considered to be an efficacious agent against a wide spectrum of human cancers, including human cervical cancer. However, dose-limiting toxicity and high cost limit its clinical application. Curcumin, a nontoxic food additive, has been reported to improve paclitaxel chemotherapy in mouse models of cervical cancer. However, the underlying mechanisms remain unclear. In this study, two human cervical cancer cell lines, CaSki [human papilloma virus (HPV)16-positive] and HeLa (HPV18-positive), were selected in which to investigate the effect of curcumin on the anticancer action of paclitaxel and further clarify the mechanisms. Flow cytometry and MTT analysis demonstrated that curcumin significantly promoted paclitaxel-induced apoptosis and cytotoxicity in the two cervical cell lines compared with that observed with paclitaxel alone (P<0.05). Reverse transcription-polymerase chain reaction indicated that the decline of HPV E6 and E7 gene expression induced by paclitaxel was also assisted by curcumin. The expression levels of p53 protein and cleaved caspase-3 were increased significantly in the curcumin plus paclitaxel-treated HeLa and CaSki cells compared with those in the cells treated with paclitaxel alone (P<0.01). Significant reductions in the levels of phosphorylation of IκBα and the p65-NF-κB subunit in CaSki cells treated with curcumin and paclitaxel were observed compared with those in cells treated with paclitaxel alone (P<0.05). This suggests that the combined effect of curcumin and paclitaxel was associated with the NF-κB-p53-caspase-3 pathway. In conclusion, curcumin has the ability to improve the paclitaxel-induced apoptosis of HPV-positive human cervical cancer cell lines via the NF-κB-p53-caspase-3 pathway. Curcumin in combination with paclitaxel may provide a superior therapeutic effect on human cervical cancer.

Inhibitory effect and mechanisms of microRNA-146b-5p on the proliferation and metastatic potential of Caski human cervical cancer cells

Cervical cancer is a common cause of cancer‑associate mortality in females, and metastasis is strongly associated with failure of cervical cancer treatment. Previous studies have indicated that microRNA (miR)‑146b‑5p is involved in the inhibition of proliferation and metastasis of numerous human cancer types. The aim of the present study was to explore the inhibitory effect of miR‑156b‑5p on the proliferation and metastatic potential of Caski human cervical cancer cells, as well as to determine the mechanisms by which it proceeds. The results demonstrated that miR‑146b‑5p was able to inhibit the proliferative, invasive and adhesive potential and block the cell cycle progression of Caski human cervical cancer cells, as determined using MTS and transwell assays as well as flow cytometry. Furthermore, quantitative polymerase chain reaction and western blot analysis revealed that transfection with miR‑146b‑5p decreased the mRNA and protein expression levels of C‑X‑C chemokine receptor type 4, matrix metalloproteinase‑2 and ‑9, c‑Myc, cyclin D1 and human papilloma virus 16. In addition, the secretion levels of transforming growth factor‑β, monocyte chemoattractant protein‑1 and tumor necrosis factor‑α, the telomerase activity, the phosphorylation of c‑Jun N‑terminal protein kinase and protein kinase B and the transcriptional activities of nuclear factor‑κB, signal transducer and activator of transcription‑3 and ‑5 were reduced. However, increased levels of p27 and p53 were detected in the miR‑146b‑5p‑overexpressing Caski cells. These results indicate that miR‑146b‑5p may be a potential therapeutic strategy for the treatment of cervical cancer through regulation of cell chemotaxis and the cell cycle.

Growth inhibition and apoptosis induction by Scutellaria pinnatifida A. Ham. on HL-60 and K562 leukemic cell lines

A rich flavonoid plant extensively used in traditional medicine is Scutellaria (Lamiaceae). In this study the cytotoxic effects of different extracts of Scutellaria pinnatifida were explored on two different cancer cell lines including K562 and HL-60 and a normal cell line. Also, the role of apoptosis on this toxicity was explored. The cell viability was quantitated by alamarBlue(®) assay. S. pinnatifida could effectively decrease the viability of malignant cells and the CH2Cl2 extract of S. pinnatifida had showed the most cytotoxic effects among other extracts. Apoptosis was confirmed after propidium iodide staining of DNA fragments and detection of the sub-G1 peak in the related flow cytometry histogram of cells. The results of western blot assay showed that CH2Cl2 extract has been able to increase the amount of Bax and cleavage of PARP protein after a 48h contact with cells. Neobaicalein (skullcapflavone II) and wogonin were identified in the extract of S. pinnatifida as the active components. The result of the present study confirmed the putative role of neobaicalein (skullcapflavone II) and wogonin as cytotoxic components in the CH2Cl2 extract of S. pinnatifida.