Quercetin modulates signaling pathways and induces apoptosis in cervical cancer cells

Dietary isothiocyanates inhibit cancer progression by modulation of epigenome

Cell cycle, growth, survival and metabolism are tightly regulated together and failure in cellular regulation leads to carcinogenesis. Several signaling pathways like the PI3K, WNT, MAPK and NFKb pathway exhibit aberrations in cancer and help achieve hallmark capabilities. Clinical research and in vitro studies have highlighted the role of epigenetic alterations in cancer onset and development. Altered gene expression patterns enabled by changes in DNA methylation, histone modifications and RNA processing have proven roles in cancer hallmark acquisition. The reversible nature of epigenetic processes offers robust therapeutic targets. Dietary bioactive compounds offer a vast compendium of effective therapeutic moieties. Isothiocyanates (ITCs) sourced from cruciferous vegetables demonstrate anti-proliferative, pro-apoptotic, anti-inflammatory, anti-migratory and anti-angiogenic effect against several cancers. ITCs also modulate the redox environment, modulate signaling pathways including PI3K, MAPK, WNT, and NFkB. They also modulate the epigenetic machinery by regulating the expression and activity of DNA methyltransferases, histone modifiers and miRNA. This further enhances their transcriptional modulation of key cellular regulators. In this review, we comprehensively assess the impact of ITCs such as sulforaphane, phenethyl isothiocyanate, benzyl isothiocyanate and allyl isothiocyanate on cancer and document their effect on various molecular targets. Overall, this will facilitate consolidation of the current understanding of the anti-cancer and epigenetic modulatory potential of these compounds and recognize the gaps in literature. Further, we discuss avenues of future research to develop these compounds as potential therapeutic entities.

Luteolin inhibits proliferation, triggers apoptosis and modulates Akt/mTOR and MAP kinase pathways in HeLa cells

Flavonoids, a subclass of polyphenols, have been shown to be effective against several types of cancer, by decreasing proliferation and inducing apoptosis. Therefore, the aim of the present study was to assess the anti-carcinogenic potential of luteolin on HeLa human cervical cancer cells, through the use of a cell viability assay, DNA fragmentation assay, mitochondrial membrane potential assay, cell cycle analysis using Annexin/PI staining and flow cytometry, gene expression analysis and a protein profiling array. Luteolin treatment exhibited cytotoxicity towards HeLa cells in a dose- and time-dependent manner, and its anti-proliferative properties were confirmed by accumulation of luteolin-treated cells in sub-G₁ phases. Cytotoxicity induced by luteolin treatment resulted in apoptosis, which was mediated through depolarization of the mitochondrial membrane potential and DNA fragmentation. Furthermore, luteolin treatment increased the expression of various proapoptotic genes, including APAF1, BAX, BAD, BID, BOK, BAK1, TRADD, FADD, FAS, and Caspases 3 and 9, whereas the expression of anti-apoptotic genes, including NAIP, MCL-1 and BCL-2, was decreased. Cell cycle regulatory genes, including CCND1, 2 and 3, CCNE2, CDKN1A, CDKN2B, CDK4 and CDK2, were decreased following treatment. Expression of TRAILR2/DR5, TRAILR1/DR4, Fas/TNFRSF6/CD95 and TNFR1/TNFRSF1A, as well as pro-apoptotic proteins, including BAD, BAX and Cytochrome C were consistently increased, and the expression of antiapoptotic proteins, HIF1α, BCL-X, MCL1 and BCL2, were found to be decreased following treatment. Expression of AKT1 and 2, ELK1, PIK3C2A, PIK3C2B, MAPK14, MAP3K5, MAPK3 and MAPK1 was significantly decreased at the transcriptional level. Expression of GSK3b (p-ser9), PRAS 40 (p-Ther246), BAD (p-ser112), PTEN (p-ser380), AKT (p-ser473), ERK2 (p-Y185/Y187), RISK2 (p-ser386), P70S6k (p-Thr421/ser424), PDK1(p-ser241), ERK1 (p-T202/Y204) and MTOR (p-ser2448) was downregulated and expression of P53 (p-ser241) and P27(p-Thr198) was upregulated by luteolin in a dose-dependent manner, indicating its anti-proliferative and apoptosis enabling properties, and this may have been mediated via inhibition of the AKT and the MAPK pathways.

Quercetin Arrests in G2 phase, Upregulates INXS LncRNA and Downregulates UCA1 LncRNA in MCF-7 Cells

One of the most prevalent malignancies, which have severe effects on women's health, is breast cancer. Quercetin, a flavonoid found in vegetables, tea, and fruits, is known to have bioactive properties, such as anti-inflammatory, anti-oxidant, as well as anti-cancer. Long non-coding RNAs (lncRNAs) have been recognized to function as primary regulators of diverse cellular processes, including differentiation, development, and cell fate. INXS and UCA1 are lncRNAs that are up regulated and down regulated respectively in cancer cells. This research aimed to assess the impact of quercetin on the expression of INXS and UCA1 genes in MCF-7 cells. Various quercetin concentrations at different times were used to treat MCF-7 cells. The cell viability and IC₅₀ values were determined using MTT assay. Then, MCF-7 cells were incubated with various quercetin concentrations for 24, 48, and 72 h. Cell cycle analyses were evaluated by flow cytometry. The levels of INXS and UCA1 gene expression compared with the GAPDH gene at different concentrations of quercetin were quantified using real-time PCR method. Based on the results, quercetin exerted a dose- and time-dependent inhibitory impact on the viability of MCF-7 cells. Furthermore, quercetin induced cell cycle arrest at the G2 phase in MCF-7 cells. Also, quercetin induced INXS upregulation and UCA1 downregulation in the MCF-7 cell line. These data suggest that quercetin might increase cell death by up regulating INXS and down regulating UCA1 lncRNAs in MCF-7 cells.

Systems Pharmacology Study of the Anticervical Cancer Mechanisms of FDY003

Increasing data support that herbal medicines are beneficial in the treatment of cervical cancer; however, their mechanisms of action remain to be elucidated. In the current study, we used a systems pharmacology approach to explore the pharmacological mechanisms of FDY003, an anticancer herbal formula comprising Lonicera japonica Thunberg, Artemisia capillaris Thunberg, and Cordyceps militaris (Linn.) Link, in the treatment of cervical cancer. Through the pharmacokinetic assessment of absorption-distribution-metabolism-excretion characteristics, we found 18 active compounds that might interact with 106 cervical cancer-related targets responsible for the pharmacological effects. FDY003 targets were significantly associated with gene ontology terms related to the regulation of cellular behaviors, including cell proliferation, cell cycle processes, cell migration, cell apoptosis, cell death, and angiogenesis. The therapeutic targets of the herbal drug were further enriched in various oncogenic pathways that are implicated in the tumorigenesis and progression of cervical cancer, including the phosphatidylinositol 3-kinase, mitogen-activated protein kinase, focal adhesion, human papillomavirus infection, and tumor necrosis factor signaling pathways. Our study provides a systematic approach to explore the anticancer properties of herbal medicines against cervical cancer.

Flavonoids Regulate Inflammation and Oxidative Stress in Cancer

Cancer is the second leading cause of death globally. Millions of persons die due to cancer each year. In the last two decades, the anticancer effects of natural flavonoids have become a hot topic in many laboratories. Meanwhile, flavonoids, of which over 8000 molecules are known to date, are potential candidates for the discovery of anticancer drugs. The current review summarizes the major flavonoid classes of anticancer efficacy and discusses the potential anti-cancer mechanisms through inflammation and oxidative stress action, which were based on database and clinical studies within the past years. The results showed that flavonoids could regulate the inflammatory response and oxidative stress of tumor through some anti-inflammatory mechanisms such as NF-κB, so as to realize the anti-tumor effect.

Quercetin promotes in vitro maturation of oocytes from humans and aged mice

Maternal fertility declines irreversibly with aging, and advanced maternal age is mostly related to impaired oocyte quality. The flavonol compound quercetin is considered to be an anti-aging agent due to its cytoprotective actions as an antioxidant. However, its role and mechanisms on aged oocytes are unclear. In this study, the quercetin promotes in vitro maturation (IVM) and early embryonic development of oocytes from aged mice. It is extended these findings in human oocytes, showing that quercetin promotes the IVM rate by 19.6% and increases the blastocyst formation rate by 15.5% compared to untreated controls. The overall oocyte quality of aged mice is improved by quercetin treatment, assessed as spindle/chromosome morphology and cortical granule distribution. Mitochondria is the primary endogenous source of age-related oxidative stress, and an RNA-seq analysis of quercetin-treated oocytes reveals molecular insights including scavenged mitochondrial-ROS, reduced apoptosis, and improved autophagy. Further, this study demonstrates that quercetin reduces ROS via SIRT3-mediated acetylation of SOD2's K68 residue. Thus, beyond demonstrating that quercetin confers beneficial mitochondria-related impacts in aged oocytes, this study illustrates a potential strategy to prevent or delay oocyte aging and to improve success rates of assisted human reproductive technologies (ART).

Epigallocatechin gallate inhibits HeLa cells by modulation of epigenetics and signaling pathways

This study examines the effect of epigallocatechin gallate (EGCG) on signaling pathways, epigenetic modulators and tumour suppressor genes in cervical cancer cells, HeLa. qRT-PCR, ELISA-based enzymatic assays and in silico studies were used to catalogue the modulation of these genes by EGCG treatment. qRT-PCR showed transcriptional modulation of several epigenetic modifiers including DNA methyltransferases and histone modifiers (DNMT1, DNMT3B, DNMT3A, AURKA, AURKC, AURKB, KDM4A, KDM5C, PRMT7, PRMT6, UBE2B, HDAC5, HDAC6, HDAC7 and HDAC11. Furthermore, ELISA-based assays showed that EGCG lowered the activity of DNA methyltransferases, histone deacetylases and histone methyltransferases (H3K9). Molecular docking results suggests that EGCG may competitively inhibit some epigenetic enzymes (DNMT1, DNMT3A, HDAC2, HDAC3, HDAC4, HDAC7 and EZH2). A functional outcome of these epigenetic alterations could be inferred from the reversal of promoter hypermethylation of tumour suppressor genes by quantitative methylation array and transcriptional re-expression of tumour suppressor genes including TP73, PTEN, SOCS1, CDH1, RARβ, and DAPK1 by qRT-PCR. Downregulation of key signaling moieties of PI3K, Wnt and MAPK pathways, cell cycle regulators, metastasis regulators and pro-inflammatory moieties including TERT, CCNB1, CCNB2, MMP2, MMP7. PIK3C2B, PIK3CA, MAPK8 and IL6 was also observed. In silico protein-protein interaction network analysis followed by KEGG analysis discerned the active participation of gene sets towards cancer pathways. This study comprehensively explains EGCG's anti-cancer mechanism via the synchronized transcriptional alteration of several molecular targets across different signaling pathways and reversal of tumour suppressor gene silencing through modulation of epigenetic enzymes.

Broad-Spectrum Preclinical Antitumor Activity of Chrysin: Current Trends and Future Perspectives

Pharmacological profile of phytochemicals has attracted much attention to their use in disease therapy. Since cancer is a major problem for public health with high mortality and morbidity worldwide, experiments have focused on revealing the anti-tumor activity of natural products. Flavonoids comprise a large family of natural products with different categories. Chrysin is a hydroxylated flavonoid belonging to the flavone category. Chrysin has demonstrated great potential in treating different disorders, due to possessing biological and therapeutic activities, such as antioxidant, anti-inflammatory, hepatoprotective, neuroprotective, etc. Over recent years, the anti-tumor activity of chrysin has been investigated, and in the present review, we provide a mechanistic discussion of the inhibitory effect of chrysin on proliferation and invasion of different cancer cells. Molecular pathways, such as Notch1, microRNAs, signal transducer and activator of transcription 3 (STAT3), nuclear factor-kappaB (NF-κB), PI3K/Akt, MAPK, etc., as targets of chrysin are discussed. The efficiency of chrysin in promoting anti-tumor activity of chemotherapeutic agents and suppressing drug resistance is described. Moreover, poor bioavailability, as one of the drawbacks of chrysin, is improved using various nanocarriers, such as micelles, polymeric nanoparticles, etc. This updated review will provide a direction for further studies in evaluating the anti-tumor activity of chrysin.

Quercetin Inhibits Proliferation and Induces Apoptosis of B16 Melanoma Cells In Vitro

Malignant melanoma is an aggressive cancer with a poor prognosis despite numerous advances in therapeutic strategies. Quercetin is a plant-derived flavonoid suggested to have potent anticancer properties. Quercetin has no demonstrable toxicity in humans, further supporting the possibility of using quercetin therapeutically. We chose to investigate quercetin efficacy against B16 murine melanoma cells and identify the mechanisms of anticancer activity. Treatment of B16 melanoma cells with 50 μg/mL quercetin resulted in a 75% reduction in viability from 6 through 48 h post-treatment. The reduction in cancer cell viability was comparable to or greater than what was observed with etoposide, an established chemotherapeutic. Specifically, we found Quercetin reduced the proliferation of B16 melanoma cells at 48 h as much or more than etoposide. Although quercetin reduced the proportion of cells in the S and G2/M stages of the cell cycle, this could largely be explained by an increase in the subG1 population in quercetin-treated cells (suggesting apoptosis). Quercetin-induced apoptosis was confirmed by flow cytometry analysis of Annexin V+ cells. Collectively, our findings demonstrate quercetin reduces proliferation and induces apoptosis of B16 melanoma cells in vitro.

A Linear Regression and Deep Learning Approach for Detecting Reliable Genetic Alterations in Cancer Using DNA Methylation and Gene Expression Data

DNA methylation change has been useful for cancer biomarker discovery, classification, and potential treatment development. So far, existing methods use either differentially methylated CpG sites or combined CpG sites, namely differentially methylated regions, that can be mapped to genes. However, such methylation signal mapping has limitations. To address these limitations, in this study, we introduced a combinatorial framework using linear regression, differential expression, deep learning method for accurate biological interpretation of DNA methylation through integrating DNA methylation data and corresponding TCGA gene expression data. We demonstrated it for uterine cervical cancer. First, we pre-filtered outliers from the data set and then determined the predicted gene expression value from the pre-filtered methylation data through linear regression. We identified differentially expressed genes (DEGs) by Empirical Bayes test using Limma. Then we applied a deep learning method, "nnet" to classify the cervical cancer label of those DEGs to determine all classification metrics including accuracy and area under curve (AUC) through 10-fold cross validation. We applied our approach to uterine cervical cancer DNA methylation dataset (NCBI accession ID: GSE30760, 27,578 features covering 63 tumor and 152 matched normal samples). After linear regression and differential expression analysis, we obtained 6287 DEGs with false discovery rate (FDR) <0.001. After performing deep learning analysis, we obtained average classification accuracy 90.69% (±1.97%) of the uterine cervical cancerous labels. This performance is better than that of other peer methods. We performed in-degree and out-degree hub gene network analysis using Cytoscape. We reported five top in-degree genes (PAIP2, GRWD1, VPS4B, CRADD and LLPH) and five top out-degree genes (MRPL35, FAM177A1, STAT4, ASPSCR1 and FABP7). After that, we performed KEGG pathway and Gene Ontology enrichment analysis of DEGs using tool WebGestalt(WEB-based Gene SeT AnaLysis Toolkit). In summary, our proposed framework that integrated linear regression, differential expression, deep learning provides a robust approach to better interpret DNA methylation analysis and gene expression data in disease study.

The Power of Phytochemicals Combination in Cancer Chemoprevention

Conventional therapies for cancer treatment have posed many challenges, including toxicity, multidrug resistance and economic expenses. In contrast, complementary alternative medicine (CAM), employing phytochemicals have recently received increased attention owing to their capability to modulate a myriad of molecular mechanisms with a less toxic effect. Increasing evidence from preclinical and clinical studies suggest that phytochemicals can favorably modulate several signaling pathways involved in cancer development and progression. Combinations of phytochemicals promote cell death, inhibit cell proliferation and invasion, sensitize cancerous cells, and boost the immune system, thus making them striking alternatives in cancer therapy. We previously investigated the effect of six phytochemicals (Indol-3-Carbinol, Resveratrol, C-phycocyanin, Isoflavone, Curcumin and Quercetin), at their bioavailable levels on breast cancer cell lines and were compared to primary cell lines over a period of 6 days. This study showed the compounds had a synergestic effect in inhibiting cell proliferation, reducing cellular migration and invasion, inducing both cell cycle arrest and apoptosis. Despite the vast number of basic science and preclinical cancer studies involving phytochemicals, the number of CAM clinical trials in cancer treatment still remains nascent. In this review, we summarize findings from preclinical and clinical studies, including our work involving use of phytochemicals, individually as well as in combination and further discuss the potential of these phytochemicals to pave way to integrate CAM in primary health care.

Neferine, an alkaloid from lotus seed embryo targets HeLa and SiHa cervical cancer cells via pro-oxidant anticancer mechanism

Apoptosis and autophagy are important processes that control cellular homeostasis and have been highlighted as promising targets for novel anticancer drugs. This study aims to investigate the inhibitory effects and mechanisms of Neferine (Nef), an alkaloid from the lotus seed embryos of Nelumbo nucifera (N. nucifera), as a dual inducer of apoptosis and autophagy through the reactive oxygen species (ROS) activation in cervical cancer cells. Nef and N. nucifera extract suppressed the cell viability of HeLa and SiHa cells in a dose-dependent manner. Importantly, Nef showed minimal toxicity to normal cells. Furthermore, Nef inhibited anchorage-independent growth, colony formation and migration ability of cervical cancer cells. Nef induces mitochondrial apoptosis by increasing pro-apoptotic protein bax, cytochrome-c, cleaved caspase-3 and caspase-9, poly-ADP ribose polymerase (PARP) cleavage, DNA damage (pH₂ AX) while downregulating Bcl-2, procaspase-3 and procaspase-9, and TCTP. Of note, apoptotic effect by Nef was significantly attenuated in the presence of N-acetylcysteine (NAC), suggesting pro-oxidant activity of this compound. Nef also promoted autophagy induction through increasing beclin-1, atg-4, atg-5 and atg-12, LC-3 activation, and _P 62/SQSTM1 as determined by western blot analysis. Collectively, these results demonstrate that Nef is a potent anticancer compound against cervical cancer cells through inducing apoptosis and autophagic pathway involving ROS.

Berberine induces dose-dependent quiescence and apoptosis in A549 cancer cells by modulating cell cyclins and inflammation independent of mTOR pathway

AIM

Emerging studies have shown that application of low concentration of bioactive phytomolecules can confer anti-proliferative effects on tumour cells by inducing senescence pathways. The alkaloid berberine is recognized for its anti-cancer attributes but its potential to induce senescence in tumour cells is least understood.

MATERIALS AND METHODS

The present work assessed the mechanisms pertaining to dose-dependent anti-proliferative effects of berberine in the perspective of senescence and inflammation using human non-small cell lung cancer cell line (A549).

KEY FINDINGS

Amongst the different tested bioactive phytomolecules, berberine treatment suppressed the proliferation of A549 cells regardless of the concentration applied. Application of low doses of berberine induced a weak SA-β-gal activity and p21^WAF1 expression but did not show evidence of SASP activation due to absence of NF-κB activation and expression of proinflammatory genes. However, treatment with higher dose of berberine showed no evidence of SA-β-gal activity or p21^WAF1 expression, but instead induced apoptosis and suppressed the expression of cell cyclins. The proliferative capacity of berberine treated cells was at par with control cells and no SA-β-gal activity could be observed in first generation of berberine treated cells. mTOR pathway showed no distinct activation on account of berberine treatment thereby further emphasizing that low dose of berberine induced quiescence and not senescence in A549 cells.

SIGNIFICANCE

Taken together, our observations indicate that despite its strong anti-proliferative effects, low dose berberine treatment may only induce transient changes akin to quiescence that needs to be considered before implying pro-senescence attributes of berberine in cancer therapeutics.

Effects of phytochemicals on cellular signaling: reviewing their recent usage approaches

Most of the previous studies in last three decades report evidence of interactions between the different phytochemicals and the proteins involved in signal transduction pathways using in silico, in vitro, ex vivo, and in vivo analyses. However, extrapolation of these findings for clinical purposes has not been that fruitful. The efficacy of the phytochemicals in vivo studies is limited by parameters such as solubility, metabolic degradation, excretion, etc. Various approaches have now been devised to circumvent these limitations. Recently, chemical modification of the phytochemicals are demonstrated to reduce some of the limitations and improve their efficacy. Similar to traditional medicines several combinatorial phytochemical formulations have shown to be more efficient. Further, phytochemicals have been reported to be even more efficient in the form of nanoparticles. However, systematic evaluation of their efficacy, mode of action in pathway modulation, usage and associated challenges is required to be done. The present review begins with basic understanding of how signaling cascades regulate cellular response and the consequences of their dysregulation further summarizing the developments and problems associated with the dietary phytochemicals and also discuss recent approaches in strengthening these compounds in pharmacological applications. Only context relevant studies have been reviewed. Considering the limitations and scope of the article, authors do not claim inclusion of all the early and recent studies.