Mechanisms of dihydrotestosterone action on resveratrol-induced anti-proliferation in breast cancer cells with different ERα status

Progesterone modulates cell growth via integrin αvβ3-dependent pathway in progesterone receptor-negative MDA-MB-231 cells

Progesterone (P4) plays a pivotal role in regulating the cancer progression of various types, including breast cancer, primarily through its interaction with the P4 receptor (PR). In PR-negative breast cancer cells, P4 appears to function in mediating cancer progression, such as cell growth. However, the mechanisms underlying the roles of P4 in PR-negative breast cancer cells remain incompletely understood. This study aimed to investigate the effects of P4 on cell proliferation, gene expression, and signal transduction in PR-negative MDA-MB-231 breast cancer cells. P4-activated genes, associated with proliferation in breast cancer cells, exhibit a stimulating effect on cell growth in PR-negative MDA-MB-231 cells, while demonstrating an inhibitory impact in PR-positive MCF-7 cells. The use of arginine-glycine-aspartate (RGD) peptide successfully blocked P4-induced extracellular signal-regulated kinase 1/2 (ERK1/2) activation, aligning with computational models of P4 binding to integrin αvβ3. Disrupting integrin αvβ3 binding with RGD peptide or anti-integrin αvβ3 antibody altered P4-induced expression of proliferative genes and modified P4-induced cell growth in breast cancer cells. In conclusion, integrin αvβ3 appears to mediate P4-induced ERK1/2 signal pathway to regulate proliferation via alteration of proliferation-related gene expression in PR-negative breast cancer cells.

The anticancer mechanism of action of selected polyphenols in triple-negative breast cancer (TNBC)

Breast cancer is a leadingcause of cancer-related deaths in women globally, with triple-negative breast cancer (TNBC) being an aggressive subtype that lacks targeted therapies and is associated with a poor prognosis. Polyphenols, naturally occurring compounds in plants, have been investigated as a potential therapeutic strategy for TNBC. This review provides an overview of the anticancer effects of polyphenols in TNBC and their mechanisms of action. Several polyphenols, including resveratrol, quercetin, kaempferol, genistein, epigallocatechin-3-gallate, apigenin, fisetin, hesperetin and luteolin, have been shown to inhibit TNBC cell proliferation, induce cell cycle arrest, promote apoptosis, and suppress migration/invasion in preclinical models. The molecular mechanisms underlying their anticancer effects involve the modulation of several signalling pathways, such as PI3K/Akt, MAPK, STATT, and NF-κB pathways. Polyphenols also exhibit synergistic effects with chemotherapy drugs, making them promising candidates for combination therapy. The review also highlights clinical trials investigating the potential use of polyphenols, individually or in combination therapy, against breast cancer. This review deepens the under-standing of the mechanism of action of respective polyphenols and provides valuable insights into the potential use of polyphenols as a therapeutic strategy for TNBC, and lays the groundwork for future research in this area.

Integrins and Actions of Androgen in Breast Cancer

Androgen has been shown to regulate male physiological activities and cancer proliferation. It is used to antagonize estrogen-induced proliferative effects in breast cancer cells. However, evidence indicates that androgen can stimulate cancer cell growth in estrogen receptor (ER)-positive and ER-negative breast cancer cells via different types of receptors and different mechanisms. Androgen-induced cancer growth and metastasis link with different types of integrins. Integrin αvβ3 is predominantly expressed and activated in cancer cells and rapidly dividing endothelial cells. Programmed death-ligand 1 (PD-L1) also plays a vital role in cancer growth. The part of integrins in action with androgen in cancer cells is not fully mechanically understood. To clarify the interactions between androgen and integrin αvβ3, we carried out molecular modeling to explain the potential interactions of androgen with integrin αvβ3. The androgen-regulated mechanisms on PD-L1 and its effects were also addressed.

Androgen signalling in the ovaries and endometrium

Currently, our understanding of hormonal regulation within the female reproductive system is largely based on our knowledge of estrogen and progesterone signalling. However, while the important functions of androgens in male physiology are well known, it is also recognized that androgens play critical roles in the female reproductive system. Further, androgen signalling is altered in a variety of gynaecological conditions, including endometriosis and polycystic ovary syndrome, indicative of regulatory roles in endometrial and ovarian function. Co-regulatory mechanisms exist between different androgens, estrogens, and progesterone, resulting in a complex network of steroid hormone interactions. Evidence from animal knockout studies, in vitro experiments, and human data indicate that androgen receptor expression is cell-specific and menstrual cycle stage-dependent, with important regulatory roles in the menstrual cycle, endometrial biology, and follicular development in the ovaries. This review will discuss the expression and co-regulatory interactions of androgen receptors, highlighting the complexity of the androgen signalling pathway in the endometrium and ovaries, and the synthesis of androgens from additional alternative pathways previously disregarded as male-specific. Moreover, it will illustrate the challenges faced when studying androgens in female biology, and the need for a more in-depth, integrative view of androgen metabolism and signalling in the female reproductive system.

Therapeutic Effects of Polyphenols on the Treatment of Colorectal Cancer by Regulating Wnt β-Catenin Signaling Pathway

Colorectal cancer (CRC) is the third most common cause of cancer-related death worldwide in terms of both its rates of incidence and mortality. Due to serious side effects associated with conventional chemotherapeutic treatments, many natural products with fewer adverse side effects have been considered as potential treatment options. In fact, many natural products have widely been used in various phases of clinical trials for CRC, as well as in in vitro and in vivo preclinical studies. Curcumin (CUR) and resveratrol (RES) are classified as natural polyphenolic compounds that have been demonstrated to have anticancer activity against CRC and are associated with minimal side effects. By regulating select target genes involved in several key signaling pathways in CRC, in particular, the Wnt β-catenin signaling cascade, the course of CRC may be positively altered. In the current review, we focused on the therapeutic effects of CUR and RES in CRC as they pertain to modulation of the Wnt β-catenin signaling pathway.

Nanomaterial Complexes Enriched With Natural Compounds Used in Cancer Therapies: A Perspective for Clinical Application

Resveratrol and quercetin are natural compounds contained in many foods and beverages. Reports indicate implications for the health of the general population; on the other hand the use of both compounds has interesting results for the treatment of many diseases as cardiovascular affections, diabetes, Alzheimer’s disease, viral and bacterial infections among others. Based on their capacities described as anti-inflammatory, antioxidant, and anti-aging, resveratrol and quercetin showed antiproliferative and anticancer activity specifically in maligned cells. These molecular characteristics trigger the pharmacological repurposing of both compounds and improved its research for treating different cancer types with interesting results at in vitro, in vivo, and clinical trial studies. Meanwhile, the development of different systems of drug release in specific sites as nanomaterials and specifically the nanoparticles, potentiates the personal treatment perspective in conjunct with the actual cancer therapies; regularly invasive and aggressive, the perspective of nanomedicine as higher effective and lower invasive has gained popularity. Knowledge of molecular interactions of resveratrol and quercetin in diseases confirms the evidence of multiple benefits, while the multiple analyses suggested a positive response for the treatment and diagnostics of cancer in different stages, including at metastatic stage. The present work reviews the reports related to the impact of resveratrol and quercetin in cancer treatment and its effects when the antioxidants are encapsulated in different nanoparticle systems, which improve the prospects of cancer treatment.

Nongenomic Actions of Thyroid Hormone: The Integrin Component

The extracellular domain of plasma membrane integrin αvβ3 contains a cell surface receptor for thyroid hormone analogues. The receptor is largely expressed and activated in tumor cells and rapidly dividing endothelial cells. The principal ligand for this receptor is l-thyroxine (T₄), usually regarded only as a prohormone for 3,5,3'-triiodo-l-thyronine (T₃), the hormone analogue that expresses thyroid hormone in the cell nucleus via nuclear receptors that are unrelated structurally to integrin αvβ3. At the integrin receptor for thyroid hormone, T₄ regulates cancer and endothelial cell division, tumor cell defense pathways (such as anti-apoptosis), and angiogenesis and supports metastasis, radioresistance, and chemoresistance. The molecular mechanisms involve signal transduction via mitogen-activated protein kinase and phosphatidylinositol 3-kinase, differential expression of multiple genes related to the listed cell processes, and regulation of activities of other cell surface proteins, such as vascular growth factor receptors. Tetraiodothyroacetic acid (tetrac) is derived from T₄ and competes with binding of T₄ to the integrin. In the absence of T₄, tetrac and chemically modified tetrac also have anticancer effects that culminate in altered gene transcription. Tumor xenografts are arrested by unmodified and chemically modified tetrac. The receptor requires further characterization in terms of contributions to nonmalignant cells, such as platelets and phagocytes. The integrin αvβ3 receptor for thyroid hormone offers a large panel of cellular actions that are relevant to cancer biology and that may be regulated by tetrac derivatives.

Integrin αvβ3 in the Mediating Effects of Dihydrotestosterone and Resveratrol on Breast Cancer Cell Proliferation

Hormones and their receptors play an important role in the development and progression of breast cancer. Hormones regulate the proliferation of breast cancer cells through binding between estrogen or progestins and steroid receptors that may reside in the cytoplasm or be transcriptionally activated as steroid–protein nuclear receptor complexes. However, receptors for nonpeptide hormones also exist in the plasma membrane. Via those receptors, hormones are able to stimulate breast cancer cell proliferation when activated. Integrins are heterodimeric structural proteins of the plasma membrane. Their primary functions are to interact with extracellular matrix proteins and growth factors. Recently, integrin αvβ3 has been identified as a receptor for nonpeptide hormones, such as thyroid hormone and dihydrotestosterone (DHT). DHT promotes the proliferation of human breast cancer cells through binding to integrin αvβ3. A receptor for resveratrol, a polyphenol stilbene, also exists on this integrin in breast cancer cells, mediating the anti-proliferative, pro-apoptotic action of the compound in these cells. Unrelated activities of DHT and resveratrol that originate at integrin depend upon downstream stimulation of mitogen-activated protein kinase (MAPK, ERK1/2) activity, suggesting the existence of distinct, function-specific pools of ERK1/2 within the cell. This review will discuss the features of these receptors in breast cancer cells, in turn suggesting clinical applications that are based on the interactions of resveratrol/DHT with integrin αvβ3 and other androgen receptors.

Role of natural compounds in preventing and treating breast cancer

Breast cancer (BrCa) is the most commonly diagnosed cancer and the second leading cause of cancer-related death in women. Alarming increases in the cases quests for more effective treatment of BrCa. As most chemotherapeutic drugs are associated with drug resistance, cancer relapse, and side effects, scientists are turning to agents with more efficacy, such as natural compounds for treatment and prevention of BrCa. Selected natural compounds, substances derived from living organisms, promote apoptosis and inhibit metastasis, preventing cancer growth. As a result, these compounds have the potential to suppress BrCa progression, thus increasing patient survival rates and decreasing the number of BrCa-related deaths. In this review, we summarize natural compounds that have displayed, anti-cancer effects on BrCa cells in various studies. These natural compounds inhibit the development of BrCa, suppress the growth of cancer cells, and promote cell death. We conclude that natural compounds are efficient, effective and promising agents for treating BrCa other than therapeutic methods.

Leptin-derived peptides block leptin-induced proliferation by reducing expression of pro-inflammatory genes in hepatocellular carcinoma cells

The obesity-regulated gene, leptin, is essential for diet. Leptin resistance causes obesity and related diseases. Certain types of diet are able to decrease leptin resistance. However, leptin has been shown to be correlated with inflammation and stimulate proliferation of various cancers. Two synthetic leptin derivatives (mimetics), OB3 and [D-Leu-4]-OB3, show more effective than leptin in reducing obesity and diabetes in mouse models. OB3 inhibits leptin-induced proliferation in ovarian cancer cells. However, effects of these mimetics in hepatocellular carcinoma (HCC) have not been investigated. In the present study, we examined the effects of OB3 and [D-Leu-4]-OB3 on cell proliferation and gene expressions in human HCC cell cultures. In contrast to what was reported for leptin, OB3 and [D-Leu-4]-OB3 reduced cell proliferation in hepatomas. Both OB3 and [D-Leu-4]-OB3 stimulated expression of pro-apoptotic genes. Both compounds also inhibited expressions of pro-inflammatory, proliferative and metastatic genes and PD-L1 expression. In combination with leptin, OB3 inhibited leptin-induced cell proliferation and expressions of pro-inflammation-, and proliferation-related genes. Furthermore, the OB3 peptide inhibited phosphoinositide 3-kinase (PI3K) activation which is essential for leptin-induced proliferation in HCC. These results indicate that OB3 and [D-Leu-4]-OB3 may have the potential to reduce leptin-related inflammation and proliferation in HCC cells.

The Mediterranean Diet as source of bioactive compounds with multi-targeting anti-cancer profile

Many bioactive agents have been extracted from plants or belong to functional foods and have been considered in the treatment of serious and multifactorial diseases, such as cancer. In particular, this review is focused on the anti-cancer properties owned by several natural products typically from the Mediterranean area. In some regions of the South of Italy, a lower cancer incidence has been observed. There is increasing evidence that adherence to a Mediterranean dietary pattern correlates with reduced risk of several cancer types. This could be mainly attributed to the typical lifestyle aspects of the Mediterranean diet, such as high consumption of fruit and vegetables. In this review, the main natural products of the Mediterranean area are discussed, with particular attention on their anti-cancer properties endowed with multi-target profiles.

Thyroid hormone-induced expression of inflammatory cytokines interfere with resveratrol-induced anti-proliferation of oral cancer cells

Thyroid hormone, L-thyroxine (T₄), induces inflammatory genes expressions and promotes cancer growth. It also induces expression of the checkpoint programmed death-ligand 1 (PD-L1), which plays a vital role in cancer progression. On the other hand, resveratrol inhibits inflammatory genes expressions. Moreover, resveratrol increases nuclear inducible cyclooxygenase (COX)-2 accumulation, complexes with p53, and induces p53-dependent anti-proliferation. In this study, we investigated the effect of T₄ on resveratrol-induced anti-proliferation in oral cancer. T₄ increased the expression and cytoplasmic accumulation of PD-L1. Increased expressions of pro-inflammatory genes, interleukin (IL)-1β and transforming growth factor (TGF)-β1, were shown to stimulate PD-L1 expression. T₄ stimulated pro-inflammatory and proliferative genes expressions, and oral cancer cells proliferation. In contrast, resveratrol inhibited those genes and activated anti-proliferative genes. T₄ retained resveratrol-induced COX-2 in cytoplasm and prevented COX-2 nuclear accumulation when resveratrol treated cancer cells. A specific signal transducer and activator of transcription 3 (STAT3) inhibitor, S31-201, blocked T₄-induced inhibition and restored resveratrol-induced nuclear COX-2 accumulation. By inhibiting the T₄-activated STAT3 signal transduction axis with S31-201, resveratrol was able to sequentially reestablish COX-2/p53-dependent gene expressions and anti-proliferation. These findings provide a novel understanding of the inhibitory effects of T₄ on resveratrol-induced anticancer properties via the sequential expression of PD-L1 and inflammatory genes.

Anti-colorectal cancer targets of resveratrol and biological molecular mechanism: Analyses of network pharmacology, human and experimental data

In this study, colorectal cancer (CRC)-diseased targets and resveratrol (Res)-associated targets were combined and constructed by the use of grouped databases for identification of the predicted targets. After production of target-functional protein interaction network of Res anti-CRC, the topological analysis was used to create the core targets of Res anti-CRC. All core targets performed the analyses of biological function and pathway enrichment to optimize the biological processes and key signaling pathways of Res anti-CRC. The resultant five core therapeutic targets of Res anti-CRC were identified as protein kinase B1 (AKT1), interleukin 6 (IL6), Tumor protein p53 (TP53), vascular endothelial growth factor, and mitogen-activated protein kinase 1, respectively. Biological processes of Res anti-CRC were predominantly associated with regulating apoptosis, immune response, cellular communication, signal transduction, and metabolism of the nuclide. In addition, the top 10 key signaling pathways were identified, respectively. In human CRC sample assays, CRC histologic sections showed elevated expression of AKT1 and IL6 proteins, accompanied with abnormal changes in blood molecules. In pharmacological experiments of Res anti-CRC in vitro, Res-treated HCT116 cells showed inhibited cell growth, induced cell death. In addition, downregulation of intracellular AKT1 and IL6 expression were checked in Res-treated HCT116 cells. Taken together, these bioinformatic findings and preliminary validated data uncovered pharmacological molecular mechanisms associated with Res anti-CRC, and further identified top five core therapeutic targets. Beneficially, these five predicted targets might serve as potential biomolecules for anti-CRC treatment.

Resveratrol antagonizes thyroid hormone-induced expression of checkpoint and proliferative genes in oral cancer cells

Background/purpose

Dysregulation of cell cycle checkpoint control may lead to the independence of growth regulating signals. Checkpoint protein such as the PD-1/PD-L1 immune checkpoint involving tumor cells and host immune defense lymphocytes is a well-studied therapeutic target in oncology. Acting at a cell surface receptor on plasma membrane integrin αvβ3, thyroxine stimulates intracellular accumulation of PD-L1 in cancer cells. Although resveratrol also binds to integrin αvβ3, it reduces PD-L1 expression.

Materials and methods

In current studies, we investigated the roles of resveratrol and thyroxine in regulating expression of proliferation-related genes and checkpoint genes, PD-L1, BTLA in two oral cancer cell lines.

Results

Thyroxine suppressed the expression of pro-apoptotic BAD but induced proliferative CCND1 expression in SSC-25 cells and OEC-M1 cells. It activated expression of PD-L1 and BTLA in both cell lines. On the other hand, resveratrol suppressed the expression of all. Alternatively, it activated BAD expression. Thus thyroxine induces checkpoint gene expression which may promote proliferation in cancer cells. Alternatively, resveratrol reverses the stimulatory effects of thyroid hormone to induce anti-proliferation.

Conclusion

These findings provide new insights into the antagonizing effect of resveratrol on the thyroxine-induced expression of checkpoint genes and proliferative genes in oral cancers.

Inhibition of NF-κB Signaling Pathway by Resveratrol Improves Spinal Cord Injury

Spinal cord injury (SCI) can have a significant impact on an individual’s life. Herein, we discuss how resveratrol improves SCI by inhibiting nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway. Evidences show resveratrol suppresses NF-κB signaling pathway to exert its beneficial effects on various diseases. NF-κB signaling pathway plays a significant role in the pathophysiological mechanisms of SCI including increase in inflammation, augmentation of damage caused by free radicals and lipid peroxidation as well as facilitation of apoptosis and axonal demyelination. We also discuss mechanisms between resveratrol and NF-κB signaling pathway in the wake of SCI, which can be potential targets for resveratrol to treat SCI.

Cytotoxic, tubulin-interfering and proapoptotic activities of 4'-methylthio-trans-stilbene derivatives, analogues of trans-resveratrol

The aim of this study was to evaluate the cytotoxicity of a series of seven 4'-methylthio-trans-stilbene derivatives against cancer cells: MCF7 and A431 in comparison with non-tumorigenic MCF12A and HaCaT cells. The mechanism of anti-proliferative activity of the most cytotoxic trans-resveratrol analogs: 3,4,5-trimethoxy-4'-methylthio-trans-stilbene (3,4,5-MTS) and 2,4,5-trimethoxy-4'-methylthio-trans-stilbene (2,4,5-MTS) was analyzed and compared with the effect of trans-resveratrol. All the compounds that were studied exerted a stronger cytotoxic effect than trans-resveratrol did. MCF7 cells were the most sensitive to the cytotoxic effect of trans-resveratrol analogs with IC50 in the range of 2.1-6.0 µM. Comparing the cytotoxicity of 3,4,5-MTS and 2,4,5-MTS, a significantly higher cytotoxic activity of these compounds against MCF7 versus MCF12A was observed, whereas no significant difference was observed in cytotoxicity against A431 and HaCaT. In the series of 4'-methylthio-trans-stilbenes, 3,4,5-MTS and 2,4,5-MTS were the most promising compounds for further mechanistic studies. The proapoptotic activity of 3,4,5-MTS and 2,4,5-MTS, estimated with the use of annexin-V/propidium iodide assay, was comparable to that of trans-resveratrol. An analysis of cell cycle distribution showed a significant increase in the percentage of apoptotic cells and G2/M phase arrest in MCF7 and A431 as a result of treatment with 3,4,5-MTS, whereas trans-resveratrol tended to increase the percentage of cells in S phase, particularly in epithelial breast cells MCF12A and MCF7. Both trans-stilbene derivatives enhanced potently tubulin polymerization in a dose-dependent manner with sulfur atom participating in the interactions with critical residues of the paclitaxel binding site of β-tubulin.

Nano-Diamino-Tetrac (NDAT) Enhances Resveratrol-Induced Antiproliferation by Action on the RRM2 Pathway in Colorectal Cancers

Cancer resistance to chemotherapeutic agents is a major issue in the management of cancer patients. Overexpression of the ribonucleotide reductase regulatory subunit M2 (RRM2) has been associated with aggressive cancer behavior and chemoresistance. Nano-diamino-tetrac (NDAT) is a nanoparticulate derivative of tetraiodothyroacetic acid (tetrac), which exerts anticancer properties via several mechanisms and downregulates RRM2 gene expression in cancer cells. Resveratrol is a stilbenoid phytoalexin which binds to a specific site on the cell surface integrin αvβ3 to trigger cancer cell death via nuclear translocation of COX-2. Here we report that resveratrol paradoxically activates RRM2 gene expression and protein translation in colon cancer cells. This unanticipated effect inhibits resveratrol-induced COX-2 nuclear accumulation. RRM2 downregulation, whether achieved by RNA interference or treatment with NDAT, enhanced resveratrol-induced COX-2 gene expression and nuclear uptake which is essential to integrin αvβ3-mediated-resveratrol-induced antiproliferation in cancer cells. Elsewhere, NDAT downregulated resveratrol-induced RRM2 expression in vivo but potentiated the anticancer effect of the stilbene. These findings suggest that RRM2 appears as a cancer cell defense mechanism which can hinder the anticancer effect of the stilbene via the integrin αvβ3 axis. Furthermore, the antagonistic effect of RRM2 against resveratrol is counteracted by the administration of NDAT.

Resveratrol inhibits human leiomyoma cell proliferation via crosstalk between integrin αvβ3 and IGF-1R

Leiomyomas (myomas) are the most common benign smooth muscle cell tumor of the myometrium. Resveratrol, a stilbene, has been used as an anti-inflammatory and antitumor agent. In the current study, we investigated the inhibitory effect of resveratrol on the proliferation of primary human myoma cell cultures. Resveratrol arrested cell proliferation via integrin αvβ3. It also inhibited integrin αvβ3 expression and protein accumulation. Concurrently, constitutive AKT phosphorylation in myoma cells was inhibited by resveratrol. Expressions of proapoptotic genes, such as cyclooxygenase (COX)-2, p21 and CDKN2, were induced by resveratrol in myoma cells. On the other hand, expressions of proliferative (anti-apoptotic) genes were either inhibited, as in BCL2, or unchanged, as in cyclin D1 and proliferating cell nuclear antigen (PCNA). The accumulation of insulin-like growth factor (IGF)-1 receptor (IGF-1R) was inhibited by resveratrol in primary myoma cells. IGF-1-induced cell proliferation was inhibited by co-incubation with resveratrol. Therefore, growth modulation of myoma cells occurs via mechanisms dependent on cross-talk between integrin αvβ3 and IGF-1R. Our findings suggest that resveratrol can be considered an alternative therapeutic agent for myomas.

Thyroxine inhibits resveratrol-caused apoptosis by PD-L1 in ovarian cancer cells

Thyroid hormone, l-thyroxine (T₄), has been shown to promote ovarian cancer cell proliferation via a receptor on plasma membrane integrin αvβ3 and to induce the activation of ERK1/2 and expression of programmed death-ligand 1 (PD-L1) in cancer cells. In contrast, resveratrol binds to integrin αvβ3 at a discrete site and induces p53-dependent antiproliferation in malignant neoplastic cells. The mechanism of resveratrol action requires nuclear accumulation of inducible cyclooxygenase (COX)-2 and its complexation with phosphorylated ERK1/2. In this study, we examined the mechanism by which T₄ impairs resveratrol-induced antiproliferation in human ovarian cancer cells and found that T₄ inhibited resveratrol-induced nuclear accumulation of COX-2. Furthermore, T₄ increased expression and cytoplasmic accumulation of PD-L1, which in turn acted to retain inducible COX-2 in the cytoplasm. Knockdown of PD-L1 by small hairpin RNA (shRNA) relieved the inhibitory effect of T₄ on resveratrol-induced nuclear accumulation of COX-2- and COX-2/p53-dependent gene expression. Thus, T₄ inhibits COX-2-dependent apoptosis in ovarian cancer cells by retaining inducible COX-2 with PD-L1 in the cytoplasm. These findings provide new insights into the antagonizing effect of T₄ on resveratrol's anticancer properties.

Herbal Compounds Play a Role in Neuroprotection through the Inhibition of Microglial Activation

Since microglia possess both neuroprotective and neurotoxic potential, they play a crucial role in the central nervous system (CNS). Excessive microglial activation induces inflammation-mediated neuronal damage and degeneration. At present, numerous herbal compounds are able to suppress neurotoxicity via inhibiting microglial activation. Therefore, many researchers focus on pharmacological inhibitors of microglial activation to ameliorate neurodegenerative disorders. Further work should concentrate on the exploration of new herbal compounds, which characteristically inhibit microglial neurotoxicity, rather than modulating neuroprotection alone. In this review, we summarize these herbal compounds, which in the past several years have been shown to exert potential neuroprotective activity by inhibiting microglial activation. The therapeutic targets and pharmacological mechanisms of these compounds have also been discussed.

Effects of resveratrol, curcumin, berberine and other nutraceuticals on aging, cancer development, cancer stem cells and microRNAs

Natural products or nutraceuticals have been shown to elicit anti-aging, anti-cancer and other health-enhancing effects. A key target of the effects of natural products may be the regulation of microRNA (miR) expression which results in cell death or prevents aging, diabetes, cardiovascular and other diseases. This review will focus on a few natural products, especially on resveratrol (RES), curcumin (CUR) and berberine (BBR). RES is obtained from the skins of grapes and other fruits and berries. RES may extend human lifespan by activating the sirtuins and SIRT1 molecules. CUR is isolated from the root of turmeric (Curcuma longa). CUR is currently used in the treatment of many disorders, especially in those involving an inflammatory process. CUR and modified derivatives have been shown to have potent anti-cancer effects, especially on cancer stem cells (CSC). BBR is also isolated from various plants (e.g., Coptis chinensis) and has been used for centuries in traditional medicine to treat diseases such as adult- onset diabetes. Understanding the benefits of these and other nutraceuticals may result in approaches to improve human health.

Crosstalk between integrin αvβ3 and ERα contributes to thyroid hormone-induced proliferation of ovarian cancer cells

Ovarian cancer is the leading cause of death in gynecological diseases. Thyroid hormone promotes proliferation of ovarian cancer cells via cell surface receptor integrin αvβ3 that activates extracellular regulated kinase (ERK1/2). However, the mechanisms are still not fully understood. Thyroxine (T₄) at a physiologic total hormone concentration (10⁻⁷ M) significantly increased proliferating cell nuclear antigen (PCNA) abundance in these cell lines, as did 3, 5, 3′-triiodo-L-thyronine (T₃) at a supraphysiologic concentration. Thyroid hormone (T₄ and T₃) treatment of human ovarian cancer cells resulted in enhanced activation of the Ras/MAPK(ERK1/2) signal transduction pathway. An MEK inhibitor (PD98059) blocked hormone-induced cell proliferation but not ER phosphorylation. Knock-down of either integrin αv or β3 by RNAi blocked thyroid hormone-induced phosphorylation of ERK1/2. We also found that thyroid hormone causes elevated phosphorylation and nuclear enrichment of estrogen receptor α (ERα). Confocal microscopy indicated that both T4 and estradiol (E₂) caused nuclear translocation of integrin αv and phosphorylation of ERα. The specific ERα antagonist (ICI 182,780; fulvestrant) blocked T₄-induced ERK1/2 activation, ERα phosphorylation, PCNA expression and proliferation. The nuclear co-localization of integrin αv and phosphorylated ERα was inhibited by ICI. ICI time-course studies indicated that mechanisms involved in T₄- and E₂-induced nuclear co-localization of phosphorylated ERα and integrin αv are dissimilar. Chromatin immunoprecipitation results showed that T₄-induced binding of integrin αv monomer to ERα promoter and this was reduced by ICI. In summary, thyroid hormone stimulates proliferation of ovarian cancer cells via crosstalk between integrin αv and ERα, mimicking functions of E₂.

Tetrac downregulates β-catenin and HMGA2 to promote the effect of resveratrol in colon cancer

The molecular pathogenesis of colorectal cancer encompasses the activation of several oncogenic signaling pathways that include the Wnt/β-catenin pathway and the overexpression of high mobility group protein A2 (HMGA2). Resveratrol - the polyphenolic phytoalexin - binds to integrin αvβ3 to induce apoptosis in cancer cells via cyclooxygenase 2 (COX-2) nuclear accumulation and p53-dependent apoptosis. Tetraiodothyroacetic acid (tetrac) is a de-aminated derivative of l-thyroxine (T₄), which - in contrast to the parental hormone - impairs cancer cell proliferation. In the current study, we found that tetrac promoted resveratrol-induced anti-proliferation in colon cancer cell lines, in primary cultures of colon cancer cells, and in vivo The mechanisms implicated in this action involved the downregulation of nuclear β-catenin and HMGA2, which are capable of compromising resveratrol-induced COX-2 nuclear translocation. Silencing of either β-catenin or HMGA2 promoted resveratrol-induced anti-proliferation and COX-2 nuclear accumulation which is essential for integrin αvβ3-mediated-resveratrol-induced apoptosis in cancer cells. Concurrently, tetrac enhanced nuclear abundance of chibby family member 1, the nuclear β-catenin antagonist, which may further compromise the nuclear β-catenin-dependent gene expression and proliferation. Taken together, these results suggest that tetrac targets β-catenin and HMGA2 to promote resveratrol-induced-anti-proliferation in colon cancers, highlighting its potential in anti-cancer combination therapy.

Beyond the Matrix: The Many Non-ECM Ligands for Integrins

The traditional view of integrins portrays these highly conserved cell surface receptors as mediators of cellular attachment to the extracellular matrix (ECM), and to a lesser degree, as coordinators of leukocyte adhesion to the endothelium. These canonical activities are indispensable; however, there is also a wide variety of integrin functions mediated by non-ECM ligands that transcend the traditional roles of integrins. Some of these unorthodox roles involve cell-cell interactions and are engaged to support immune functions such as leukocyte transmigration, recognition of opsonization factors, and stimulation of neutrophil extracellular traps. Other cell-cell interactions mediated by integrins include hematopoietic stem cell and tumor cell homing to target tissues. Integrins also serve as cell-surface receptors for various growth factors, hormones, and small molecules. Interestingly, integrins have also been exploited by a wide variety of organisms including viruses and bacteria to support infectious activities such as cellular adhesion and/or cellular internalization. Additionally, the disruption of integrin function through the use of soluble integrin ligands is a common strategy adopted by several parasites in order to inhibit blood clotting during hematophagy, or by venomous snakes to kill prey. In this review, we strive to go beyond the matrix and summarize non-ECM ligands that interact with integrins in order to highlight these non-traditional functions of integrins.

Novel leptin OB3 peptide-induced signaling and progression in thyroid cancers: Comparison with leptin

Obesity results in increased secretion of cytokines from adipose tissue and is a risk factor for various cancers. Leptin is largely produced by adipose tissue and cancer cells. It induces cell proliferation and may serve to induce various cancers. OB3-leptin peptide (OB3) is a new class of functional leptin peptide. However, its mitogenic effect has not been determined. In the present study, because of a close link between leptin and the hypothalamic-pituitary-thyroid axis, OB3 was compared with leptin in different thyroid cancer cells for gene expression, proliferation and invasion. Neither agent stimulated cell proliferation. Leptin stimulated cell invasion, but reduced adhesion in anaplastic thyroid cancer cells. Activated ERK1/2 and STAT3 contributed to leptin-induced invasion. In contrast, OB3 did not affect expression of genes involved in proliferation and invasion. In vivo studies in the mouse showed that leptin, but not OB3, significantly increased circulating levels of thyrotropin (TSH), a growth factor for thyroid cancer. In summary, OB3 is a derivative of leptin that importantly lacks the mitogenic effects of leptin on thyroid cancer cells.

Celecoxib targets breast cancer stem cells by inhibiting the synthesis of prostaglandin E2 and down-regulating the Wnt pathway activity

Pharmacological targeting of breast cancer stem cells (CSCs) is highly promising for the treatment of breast cancer, as the small population of CSCs is responsible for tumor initiation, progression, recurrence and chemo-resistance. Celecoxib is one of the most commonly used non-steroidal anti-inflammatory drugs (NSAIDs), which have chemo-preventive activity against cancers, including breast cancer and colorectal cancer. However, the mechanisms by which NSAIDs exert its cancer prevention effects have yet been completely understood. In the present study, we investigated for the first time the effect of celecoxib on breast CSCs inhibition and its potential molecular mechanisms. Our results demonstrated that celecoxib suppresses CSC self-renewal, sensitizes chemo-resistance, inhibits epithelial to mesenchymal transition (EMT), and attenuates metastasis and tumorigenesis. Further exploring the underlying mechanism revealed that celecoxib targets breast CSCs by inhibiting the synthesis of prostaglandin E₂ and down-regulating the Wnt pathway activity. Our findings suggest that celecoxib, by targeting CSCs, may be used as an adjuvant chemotherapy drug to improve breast cancer treatment outcomes.

Resveratrol induces sumoylated COX-2-dependent anti-proliferation in human prostate cancer LNCaP cells

Cyclooxygenase (COX)-2 has been implicated in cancer development. However, resveratrol-induced nuclear accumulation of COX-2 enhances p53-dependent anti-proliferation in different types of cancers. Treatment with resveratrol leads to phosphorylation and nuclear translocation of mitogen-activated protein kinase (ERK1/2), and accumulation of nuclear COX-2 to complex with pERK1/2 and p53. The consequence is Ser-15 phosphorylation of p53 (pSer15-p53), and induction of anti-proliferation in cancer cells. We investigated the mechanisms by which resveratrol-inducible COX-2 facilitates p53-dependent anti-proliferation in prostate cancer LNCaP cells. Resveratrol treatment caused nuclear accumulation and complexing of ERK1/2, pSer15-p53 and COX-2 which was activated ERK1/2-dependent. Knockdown of SUMO-1 by shRNA also reduced nuclear accumulation of COX-2. Inhibition of nuclear accumulation by the COX-2 specific inhibitor, NS-398, inhibited co-localization of nuclear COX-2 and SUMO-1. Similar results were observed in the PD98059-treated cells. Finally, inhibition of SUMO-1 expression also reduced resveratrol-induced expression of pro-apoptotic genes but increased the expression of proliferative genes. In summary, these results demonstrate that inducible COX-2 associates with phosphorylated ERK1/2 to induce the phosphorylation of Ser-15 in p53 and then complexes with p53 and SUMO-1 which binds to p53-responsive pro-apoptotic genes to enhance their expression. The inhibition of COX-2 expression and activity significantly blocks the pro-apoptotic effect of resveratrol.

Mechanisms of action of nonpeptide hormones on resveratrol-induced antiproliferation of cancer cells

Nonpeptide hormones, such as thyroid hormone, dihydrotestosterone, and estrogen, have been shown to stimulate cancer proliferation via different mechanisms. Aside from their cytosolic or membrane-bound receptors, there are receptors on integrin α_v β₃ for nonpeptide hormones. Interaction between hormones and integrin α_v β₃ can induce signal transduction and eventually stimulate cancer cell proliferation. Resveratrol induces inducible COX-2-dependent antiproliferation via integrin α_v β₃ . Resveratrol and hormone-induced signals are both transduced by activated extracellular-regulated kinases 1 and 2 (ERK1/2); however, hormones promote cell proliferation, while resveratrol induces antiproliferation in cancer cells. Hormones inhibit resveratrol-stimulated phosphorylation of p53 on Ser15, resveratrol-induced nuclear COX-2 accumulation, and formation of p53-COX-2 nuclear complexes. Subsequently, hormones impair resveratrol-induced COX-2-/p53-dependent gene expression. The inhibitory effects of hormones on resveratrol action can be blocked by different antagonists of specific nonpeptide hormone receptors but not integrin α_v β₃ blockers. Results suggest that nonpeptide hormones inhibit resveratrol-induced antiproliferation in cancer cells downstream of the interaction between ligand and receptor and ERK1/2 activation to interfere with nuclear COX-2 accumulation. Thus, the surface receptor sites for resveratrol and nonpeptide hormones are distinct and can induce discrete ERK1/2-dependent downstream antiproliferation biological activities. It also indicates the complex pathways by which antiproliferation is induced by resveratrol in various physiological hormonal environments. .

Cellular and Molecular Targets of Resveratrol on Lymphoma and Leukemia Cells

Resveratrol (RSV) is a well known chemopreventive molecule featuring anti-cancer properties. Our paper describes the main molecular targets of RSV linked to its antiproliferative activity on lymphoma and leukemia experimental models. It discusses further the most recent and most promising among these molecular targets for a translational application.

Downregulation of mitochondrial cyclooxygenase-2 inhibits the stemness of nasopharyngeal carcinoma by decreasing the activity of dynamin-related protein 1

Cancer stem cells (CSCs) are a small subset of malignant cells, possessing stemness, with strong tumorigenic capability, conferring resistance to therapy and leading to the relapse of nasopharyngeal carcinoma (NPC). Our previous study suggested that cyclooxygenase-2 (COX-2) would be a novel target for the CSCs-like side population (SP) cells in NPC. In the present study, we further found that COX-2 maintained the stemness of NPC by enhancing the activity of mitochondrial dynamin-related protein 1 (Drp1), a mitochondrial fission mediator, by studying both sorted SP cells from NPC cell lines and gene expression analyses in NPC tissues. Using both overexpression and knockdown of COX-2, we demonstrated that the localization of COX-2 at mitochondria promotes the stemness of NPC by recruiting the mitochondrial translocation of p53, increasing the activity of Drp1 and inducing mitochondrial fisson. Inhibition of the expression or the activity of Drp1 by siRNA or Mdivi-1 downregulates the stemness of NPC. The present study also found that inhibition of mitochondrial COX-2 with resveratrol (RSV), a natural phytochemical, increased the sensitivity of NPC to 5-fluorouracil (5-FU), a classical chemotherapy drug for NPC. The underlying mechanism is that RSV suppresses mitochondrial COX-2, thereby reducing NPC stemness by inhibiting Drp1 activity as demonstrated in both the in vitro and the in vivo studies. Taken together, the results of this study suggest that mitochondrial COX-2 is a potential theranostic target for the CSCs in NPC. Inhibition of mitochondrial COX-2 could be an attractive therapeutic option for the effective clinical treatment of therapy-resistant NPC.

Methylation changes of SIRT1, KLF4, DAPK1 and SPG20 in B-lymphocytes derived from follicular and diffuse large B-cell lymphoma

Diffuse large-B cell lymphomas (DLBCL) and follicular lymphomas (FL) are the most represented subtypes among mature B-cell neoplasms and originate from malignant B lymphocytes. Methylation represents one of the major epigenetic mechanisms of gene regulation. Silent information regulator 1 (SIRT1) is a class III lysine-deacetylase playing several functions and considered to be a context-dependent tumor promoter. We present the quantitative methylation, gene expression and tissue distribution of SIRT1 and some key mediators related to lymphoma pathogenesis in B lymphocytes purified from biopsies of follicular hyperplasias, FL and DLBCL. SIRT1 mRNA levels are higher in FL than follicular hyperplasias and DLBCL. B cell lymphoma 6 (BCL6) positively correlates with SIRT1. SIRT1 promoter shows a methylation decrease in the order: follicular hyperplasia - FL - DLBCL. Kruppel-like factor 4 (KLF4), Death-associated protein kinase 1 (DAPK1) and Spastic Paraplegia 20 (SPG20) methylation increase significantly in FL and DLBCL compared to follicular hyperplasias. Gene expression of DAPK1 and SPG20 inversely correlates with their degree of methylation. Our findings evidence a positive correlation between SIRT1 and BCL6 expression increase in FL. SIRT1 methylation decreases in FL and DLBCL accordingly and this parallels the increase of KLF4, DAPK1 and SPG20 methylation.

Anticancer Molecular Mechanisms of Resveratrol

Resveratrol is a pleiotropic phytochemical belonging to the stilbene family. Though it is only significantly present in grape products, a huge amount of preclinical studies investigated its anticancer properties in a plethora of cellular and animal models. Molecular mechanisms of resveratrol involved signaling pathways related to extracellular growth factors and receptor tyrosine kinases; formation of multiprotein complexes and cell metabolism; cell proliferation and genome instability; cytoplasmic tyrosine kinase signaling (cytokine, integrin, and developmental pathways); signal transduction by the transforming growth factor-β super-family; apoptosis and inflammation; and immune surveillance and hormone signaling. Resveratrol also showed a promising role to counteract multidrug resistance: in adjuvant therapy, associated with 5-fluoruracyl and cisplatin, resveratrol had additive and/or synergistic effects increasing the chemosensitization of cancer cells. Resveratrol, by acting on diverse mechanisms simultaneously, has been emphasized as a promising, multi-target, anticancer agent, relevant in both cancer prevention and treatment.