Suppression of Akt/Foxp3-mediated miR-183 expression blocks Sp1-mediated ADAM17 expression and TNFα-mediated NFκB activation in piceatannol-treated human leukemia U937 cells

Beta-Transducin Repeats-Containing Proteins as an Anticancer Target

Beta-transducin repeat-containing proteins (β-TrCPs) are E3-ubiquitin-ligase-recognizing substrates and regulate proteasomal degradation. The degradation of β-TrCPs' substrates is tightly controlled by various external and internal signaling and confers diverse cellular processes, including cell cycle progression, apoptosis, and DNA damage response. In addition, β-TrCPs function to regulate transcriptional activity and stabilize a set of substrates by distinct mechanisms. Despite the association of β-TrCPs with tumorigenesis and tumor progression, studies on the mechanisms of the regulation of β-TrCPs' activity have been limited. In this review, we studied publications on the regulation of β-TrCPs themselves and analyzed the knowledge gaps to understand and modulate β-TrCPs' activity in the future.

Dietary stilbenes as modulators of specific miRNAs in prostate cancer

Accumulated experimental data have suggested that natural plant products may be effective miRNA-modulating chemopreventive and therapeutic agents. Dietary polyphenols such as flavonoids, stilbenes, and lignans, among others, have been intensively studied for their miRNA-mediated cardioprotective, antioxidant, anti-inflammatory and anticancer properties. The aim of this review is to outline known stilbene-regulated miRNAs in cancer, with a special focus on the interplay between various miRNAs and MTA1 signaling in prostate cancer. MTA1 is an epigenetic reader and an oncogenic transcription factor that is overexpressed in advanced prostate cancer and metastasis. Not surprisingly, miRNAs that are linked to MTA1 affect cancer progression and the metastatic potential of cells. Studies led to the identification of MTA1-associated pro-oncogenic miRNAs, which are regulated by stilbenes such as resveratrol and pterostilbene. Specifically, it has been shown that inhibition of the activity of the MTA1 regulated oncogenic miR-17 family of miRNAs, miR-22, and miR-34a by stilbenes leads to inhibition of prostatic hyperplasia and tumor progression in mice and reduction of proliferation, survival and invasion of prostate cancer cells in vitro. Taken together, these findings implicate the use of resveratrol and its analogs as an attractive miRNA-mediated chemopreventive and therapeutic strategy in prostate cancer and the use of circulating miRNAs as potential predictive biomarkers for clinical development.

CREB/Sp1-mediated MCL1 expression and NFκB-mediated ABCB1 expression modulate the cytotoxicity of daunorubicin in chronic myeloid leukemia cells

Although some studies have hinted at the therapeutic potential of daunorubicin (DNR) in chronic myeloid leukemia (CML), the mechanism by which DNR induces CML cell death is unclear. Therefore, this study aimed to investigate DNR-induced cell death signaling pathways in CML cell lines K562 and KU812. DNR-triggered apoptosis in K562 cells was characterized by inhibition of MCL1 expression, while restoration of MCL1 expression protected K562 cells from DNR-mediated cytotoxicity. In addition, DNR induced NOX4-dependent ROS production, leading to the activation of p38 MAPK and inactivation of Akt and ERK. Activated p38 MAPK stimulated protein phosphatase 2A-dependent dephosphorylation of CREB. Since Akt-mediated activation of ERK reduced β-TrCP mRNA stability, the inactivation of Akt-ERK axis increased β-TrCP expression, which in turn promoted proteasomal degradation of Sp1. Inhibition of CREB phosphorylation and Sp1 expression simultaneously reduced MCL1 transcription and protein expression. DNR-induced MCL1 suppression was not reliant on its ability to induce DNA damage. In addition, DNR induced the expression of drug exporter ABCB1 in K562 cells through the p38 MAPK/NFκB-mediated pathway, while imatinib or ABT-199 inhibited the DNR-induced effect. The combination of imatinib or ABT-199 with DNR showed synergistic cytotoxicity in K562 cells by increasing intracellular DNR retention. Cumulatively, our data indicate that DNR induces MCL1 downregulation in K562 cells by promoting p38 MAPK-mediated dephosphorylation of CREB and inhibiting the Akt-ERK axis-mediated Sp1 protein stabilization. Furthermore, experimental evidence indicates that DNR-induced death of KU812 cells occurs through a similar pathway.

Dietary Phytoestrogens and Their Metabolites as Epigenetic Modulators with Impact on Human Health

The impact of dietary phytoestrogens on human health has been a topic of continuous debate since their discovery. Nowadays, based on their presumptive beneficial effects, the amount of phytoestrogens consumed in the daily diet has increased considerably worldwide. Thus, there is a growing need for scientific data regarding their mode of action in the human body. Recently, new insights of phytoestrogens’ bioavailability and metabolism have demonstrated an inter-and intra-population heterogeneity of final metabolites’ production. In addition, the phytoestrogens may have the ability to modulate epigenetic mechanisms that control gene expression. This review highlights the complexity and particularity of the metabolism of each class of phytoestrogens, pointing out the diversity of their bioactive gut metabolites. Futhermore, it presents emerging scientific data which suggest that, among well-known genistein and resveratrol, other phytoestrogens and their gut metabolites can act as epigenetic modulators with a possible impact on human health. The interconnection of dietary phytoestrogens’ consumption with gut microbiota composition, epigenome and related preventive mechanisms is discussed. The current challenges and future perspectives in designing relevant research directions to explore the potential health benefits of dietary phytoestrogens are also explored.

Roles for ADAM17 in TNF-R1 Mediated Cell Death and Survival in Human U937 and Jurkat Cells

Signaling via death receptor family members such as TNF-R1 mediates pleiotropic biological outcomes ranging from inflammation and proliferation to cell death. Pro-survival signaling is mediated via TNF-R1 complex I at the cellular plasma membrane. Cell death induction requires complex IIa/b or necrosome formation, which occurs in the cytoplasm. In many cell types, full apoptotic or necroptotic cell death induction requires the internalization of TNF-R1 and receptosome formation to properly relay the signal inside the cell. We interrogated the role of the enzyme A disintegrin and metalloprotease 17 (ADAM17)/TACE (TNF-α converting enzyme) in death receptor signaling in human hematopoietic cells, using pharmacological inhibition and genetic ablation. We show that in U937 and Jurkat cells the absence of ADAM17 does not abrogate, but rather increases TNF mediated cell death. Likewise, cell death triggered via DR3 is enhanced in U937 cells lacking ADAM17. We identified ADAM17 as the key molecule that fine-tunes death receptor signaling. A better understanding of cell fate decisions made via the receptors of the TNF-R1 superfamily may enable us, in the future, to more efficiently treat infectious and inflammatory diseases or cancer.

Carboxyl group-modified α-lactalbumin induces TNF-α-mediated apoptosis in leukemia and breast cancer cells through the NOX4/p38 MAPK/PP2A axis

To clarify the mechanism of semicarbazide-modified α-lactalbumin (SEM-LA)-mediated cytotoxicity, we investigated its effect on human U937 leukemia cells and MCF-7 breast cancer cells in the current study. SEM-LA induced apoptosis in U937 cells, which showed increased NOX4 expression, procaspase-8 degradation, and t-Bid production. FADD depletion inhibited SEM-LA-elicited caspase-8 activation, t-Bid production, and cell death, indicating that SEM-LA activated death receptor-mediated apoptosis in U937 cells. SEM-LA stimulated Ca²⁺-mediated Akt activation, which in turn increased Sp1- and p300-mediated NOX4 transcription. The upregulation of NOX4 expression promoted ROS-mediated p38 MAPK phosphorylation, leading to protein phosphatase 2A (PP2A)-regulated tristetraprolin (TTP) degradation. Remarkably, TTP downregulation increased the stability of TNF-α mRNA, resulting in the upregulation of TNF-α protein expression. Abolishment of Ca²⁺-NOX4-ROS axis-mediated p38 MAPK activation attenuated SEM-LA-induced TNF-α upregulation and protected U937 cells from SEM-LA-mediated cytotoxicity. The restoration of TTP expression alleviated the effect of TNF-α upregulation and cell death induced by SEM-LA. Altogether, the data in this study demonstrate that SEM-LA activates TNF-α-mediated apoptosis in U937 cells through the NOX4/p38 MAPK/PP2A axis. We think that a similar pathway can also explain the death of MCF-7 human breast cancer cells after SEM-LA treatment.

Piceatannol suppresses proliferation and induces apoptosis by regulation of the microRNA‑21/phosphatase and tensin homolog/protein kinase B signaling pathway in osteosarcoma cells

Piceatannol (Pice), a natural analog of resveratrol, has been identified as an anticancer agent in various cancers by modulating the expression of microRNAs (miRNAs/miRs). However, the molecular mechanisms underlying the anticancer effects of Pice in osteosarcoma (OS) cells remain unclear. Thus, we hypothesized that Pice exerts anticancer effects on OS cells via the regulation of miRNA expression. Herein, we performed a MTT assay and flow cytometric analysis to determine cell viability and apoptosis in OS cells treated with Pice, respectively. Our results showed that Pice inhibits proliferation in a dose-dependent manner induces the apoptosis of OS cells. More importantly, miRNA microarray analysis identified that Pice alters miRNA expression profiles in human OS cells after treatment with Pice, and miR-21 was the most significantly downregulated. In addition, the therapeutic effects of Pice on OS cells were weakened by restoration of miR-21. In addition, we further verified that phosphatase and tensin homolog (PTEN), a tumor suppressor gene, is the functional target of miR-21 and Pice blocks the PTEN/AKT signaling pathway through inhibiting miR-21 expression in OS cells. Our findings suggested that Pice may exert anticancer effects on OS cells via mediating the miR-21/PTEN/AKT signaling pathway and could be considered to be a potential anticancer agent for treating OS.

Grape Powder Supplementation Attenuates Prostate Neoplasia Associated with Pten Haploinsufficiency in Mice Fed High-Fat Diet

SCOPE

Previous studies have identified potent anticancer activities of polyphenols in preventing prostate cancer. The aim of the current study is to evaluate the chemopreventive potential of grape powder (GP) supplemented diets in genetically predisposed and obesity-provoked prostate cancer.

METHODS AND RESULTS

Prostate-specific Pten heterozygous (Pten+/f ) transgenic mice are fed low- and high-fat diet (LFD and HFD, respectively) supplemented with 10% GP for 33 weeks, ad libitum. Prostate tissues are characterized using immunohistochemistry and western blots, and sera are analyzed by ELISA and qRT-PCR. Pten+/f mice fed LFD and HFD supplemented with 10% GP show favorable histopathology, significant reduction of the proliferative rate of prostate epithelial cells (Ki67), and rescue of PTEN expression. The most potent protective effect of GP supplementation is detected against HFD-induced increase in inflammation (IL-1β; TGF-β1), activation of cell survival pathways (Akt, AR), and angiogenesis (CD31) in Pten+/f mice. Moreover, GP supplementation reduces circulating levels of oncogenic microRNAs (miR-34a; miR-22) in Pten+/f mice. There are no significant changes in body weight and food intake in GP supplemented diet groups.

CONCLUSIONS

GP diet supplementation can be a beneficial chemopreventive strategy for obesity-related inflammation and prostate cancer progression. Monitoring serum miRNAs can facilitate the non-invasive evaluation of chemoprevention efficacy.

GPR50 Promotes Hepatocellular Carcinoma Progression via the Notch Signaling Pathway through Direct Interaction with ADAM17

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide, and it is thus critical to identify novel molecular biomarkers of HCC prognosis and elucidate the molecular mechanisms underlying HCC progression. Here, we show that G-protein-coupled receptor 50 (GPR50) in HCC is overexpressed and that GPR50 knockdown may downregulate cancer cell progression through attenuation of the Notch signaling pathway. GPR50 knockdown was found to reduce HCC progression by inactivating Notch signaling in a ligand-independent manner through a disintegrin and metalloproteinase metallopeptidase domain 17 (ADAM17), a proteolytic enzyme that cleaves the Notch receptor, which was corroborated by GPR50 overexpression in hepatocytes. GPR50 silencing also downregulated transcription and translation of ADAM17 through the AKT/specificity protein-1 (SP1) signaling axis. Notably, GPR50 was found to directly interact with ADAM17. Overall, we demonstrate a novel GPR50-mediated regulation of the ADAM17-Notch signaling pathway, which can provide insights into HCC progression and prognosis and development of Notch-based HCC treatment strategies.

Albendazole-Induced SIRT3 Upregulation Protects Human Leukemia K562 Cells from the Cytotoxicity of MCL1 Suppression

Previous studies have shown that MCL1 stabilization confers cancer cells resistance to microtubule targeting agents (MTAs) and functionally extends the lifespan of MTA-triggered mitotically arrested cells. Albendazole (ABZ), a benzimidazole anthelmintic, shows microtubule-destabilizing activity and has been repositioned for cancer therapies. To clarify the role of MCL1 in ABZ-induced apoptosis, we investigated the cytotoxicity of ABZ on human leukemia K562 cells. Treatment with ABZ for 24 h did not appreciably induce apoptosis or mitochondrial depolarization in K562 cells, though it caused the mitotic arrest of K562 cells. ABZ-evoked p38 MAPK activation concurrently suppressed Sp1-mediated MCL1 expression and increased SIRT3 mRNA stability and protein expression. ABZ and A-1210477 (an MCL1 inhibitor) enhanced the cytotoxicity of ABT-263 (a BCL2/BCL2L1 inhibitor) to their effect on MCL1 suppression. Unlike ABZ, A-1210477 did not affect SIRT3 expression and reduced the survival of K562 cells. Overexpression of SIRT3 attenuated the A-1210477 cytotoxicity on K562 cells. ABZ treatment elicited marked apoptosis and ΔΨm loss in ABT-263-resistant K562 (K562/R) cells, but did not alter SIRT3 expression. Ectopic expression of SIRT3 alleviated the cytotoxicity of ABZ on K562/R cells. Collectively, our data demonstrate that ABZ-induced SIRT3 upregulation delays the apoptosis-inducing effect of MCL1 suppression on apoptosis induction in K562 cells.

MicroRNA-183 in Cancer Progression

MicroRNA-183(miR-183) is abnormally expressed in many kinds of tumors. It participates in the initiation and development of tumors. There are many pathways regulate the expression of miR-183. The action mechanism of miR-183 in cancer is very extensive, and contradictory conclusions are often drawn. It was upregulated in 18 kinds of cancer, downregulated in 6 kinds of cancer. In addition, there are seven types of cancer, both upregulated and downregulated reports can be found. Evidence showed that miR-183 can not only directly play the role of oncogene or antioncogene, but also regulate the expression of other oncogene or antioncogene in different cancer types. In this review, we discuss the regulator of miR-183 and summarized the expression of miR-183 in different cancers. We also counted the target genes of miR-183 and the functional roles they play. Furthermore, we focused on the roles of miR-183 in cell migration, cell invasion, epithelial-mesenchymal transition (EMT) and microangiogenesis, which play the most important roles in cancer processes. It sheds light on the likely reasons why miR-183 plays different roles in various cancers. In addition, miR-183 and its downstream effectors have the potential to be promising prognostic markers and therapeutic targets in cancer.

Immune evasion by TGFβ-induced miR-183 repression of MICA/B expression in human lung tumor cells

Immune escape is a hallmark of cancer. In human lung cancer, we have identified a unique microRNA (miR)-based pathway employed by tumor cells to repress detection by immune cells via the NKG2D-MICA/B receptor-ligand system. MICA/B is readily induced by cell transformation and serves as a danger signal and ligand to alert NK and activated CD8⁺ T cells. However, immunohistochemical analysis indicated that human lung adenocarcinoma and squamous cell carcinoma specimens express little MICA/B while high levels of miR-183 were detected in both tumor types in a TCGA database. Human lung tumor cell lines confirmed the reverse relationship in expression of MICA/B and miR-183. Importantly, a miR-183 binding site was identified on the 3'untranslated region (UTR) of both MICA and MICB, suggesting its role in MICA/B regulation. Luciferase reporter constructs bearing the 3'UTR of MICA or MICB in 293 cells supported the function of miR-183 in repressing MICA/B expression. Additionally, anti-sense miR-183 transfection into H1355 or H1299 tumor cells caused the upregulation of MICA/B. Abundant miR-183 expression in tumor cells was traced to transforming growth factor-beta (TGFβ), as evidenced by antisense TGFβ transfection into H1355 or H1299 tumor cells which subsequently lost miR-183 expression accompanied by MICA/B upregulation. Most significantly, anti-sense miR-183 transfected tumor cells became more sensitive to lysis by activated CD8⁺ T cells that express high levels of NKG2D. Thus, high miR-183 triggered by TGFβ expressed in lung tumor cells can target MICA/B expression to circumvent detection by NKG2D on immune cells.

The role of miR-183 cluster in immunity

MicroRNAs (miRNAs) are essential factors of an extensively conserved post-transcriptional process to regulate gene expression. MiRNAs play a pivotal role in immunity, including controlling the differentiation of various immune cells as well as their immunological functions. The miR-183 cluster, which is comprised of miR-183, -96 and -182, is a miRNA family with sequence homology. These miRNAs are usually transcribed together as a polycistronic miRNA cluster during development and are required for maturation of sensory organs. In comparison to defined sensory-specific role of these miRNAs in normal development, they are frequently over-expressed in several non-sensory diseases, including autoimmune diseases and cancers. Because individual miRNAs of miR-183 cluster have both common and unique targets within functionally interrelated pathways, they can show cooperative or opposing effects on biological processes, implying the complexity of this miR cluster-mediated gene regulation. Therefore, a better understanding of the molecular regulation of miR-183 cluster expression and its downstream networks is important for the therapeutic applications. In this review, we will discuss the characteristics of miR-183 cluster and a wide variety of evidence on its function in immune system. Newer knowledge summarized here will help readers understand the versatile role of miR-183 cluster in this field.

Dysregulation and functional roles of miR-183-96-182 cluster in cancer cell proliferation, invasion and metastasis

Previous studies have reported aberrant expression of the miR-183-96-182 cluster in a variety of tumors, which indicates its' diagnostic or prognostic value. However, a key characteristic of the miR-183-96-182 cluster is its varied expression levels, and pleomorphic functional roles in different tumors or under different conditions. In most tumor types, the cluster is highly expressed and promotes tumorigenesis, cancer progression and metastasis; yet tumor suppressive effects have also been reported in some tumors. In the present study, we discuss the upstream regulators and the downstream target genes of miR-183-96-182 cluster, and highlight the dysregulation and functional roles of this cluster in various tumor cells. Newer insights summarized in this review will help readers understand the different facets of the miR-183-96-182 cluster in cancer development and progression.

Quinacrine induces the apoptosis of human leukemia U937 cells through FOXP3/miR-183/β-TrCP/SP1 axis-mediated BAX upregulation

Quinacrine, which is clinically used as an antimalarial drug, has anti-cancer activity. However, mechanism underlying its cytotoxic effect remains to be completely elucidated. In the present study, we investigated the cytotoxic effect of quinacrine on human leukemia U937 cells. Quinacrine-induced apoptosis of U937 cells was accompanied with ROS generation, mitochondrial depolarization, and BAX upregulation. Quinacrine-treated U937 cells showed ROS-mediated p38 MAPK activation and ERK inactivation, which in turn upregulated FOXP3 transcription. FOXP3-mediated miR-183 expression decreased β-TrCP mRNA stability and suppressed β-TrCP-mediated SP1 degradation, thus increasing SP1 expression in U937 cells. Upregulated SP1 expression further increased BAX expression. BAX knock-down attenuated quinacrine-induced mitochondrial depolarization and increased the viability of quinacrine-treated cells. Together, our data indicate that quinacrine-induced apoptosis of U937 cells is mediated by mitochondrial alterations triggered by FOXP3/miR-183/β-TrCP/SP1 axis-mediated BAX upregulation.

Piceatannol induced apoptosis through up-regulation of microRNA-181a in melanoma cells

Background

Melanoma took top position among the lethal cancers and, despite there have been some great attempts made to increase the natural life of patients with metastatic disease, long-lasting and complete remissions are few. Piceatannol, owns the similar function as resveratrol, has been defined as an anti-cancer agent playing important role in inhibition of proliferation, migration and metastasis in various cancer. Thus, we aim to investigate the anti-cancer effect and mechanisms of piceatannol in melanoma cells.

Methods

Melanoma cell lines WM266-4 and A2058 were treated either with or without piceatannol. Cell viability and cell apoptosis were assessed by using MTT and Annexin V/PI assay, respectively. Cells were transfected with specific miRNA using Lipfectamine 2000. miRNA bingding ability to 3'-UTR region within specific gene was assed by firefly luciferase analysis. Gene and protein expression was eveluated by qRT-PCR and western blot analysis, respectively.

Results

Our study showed that piceatannol inhibited WM266-4 and A2058 cells growth and induced apoptosis. Totally, 16 differentially expressed miRNAs were screened out including 8 up-regulated and 8 down-regulated miRNAs. Expression level of miR-181a is significantly higher in piceatannol-treated cells than normal control and is lower in melanoma cancer tissues than its adjacent normal tissues. Bcl-2 is a target gene of miR-181a. Moreover, silencing of miR-181a reverses the decrease of cell viability induced by piceatannol in WM266-4 and A2058 cells. Taken together, present study uncovered the ability of piceatannol to repress melanoma cell growth and clarified the contribution of miR-181a in the anticancer role of piceatannol.

Conclusion

The present study proposes that piceatannol can be taken into account to be a hopeful anticancer agent for melanoma.

Resveratrol and pterostilbene as a microRNA-mediated chemopreventive and therapeutic strategy in prostate cancer

Growing evidence indicates that deregulation of the epigenetic machinery comprising the microRNA (miRNA) network is a critical factor in the progression of various diseases, including cancer. Concurrently, dietary phytochemicals are being intensively studied for their miRNA-mediated health-beneficial properties, such as anti-inflammatory, cardioprotective, antioxidative, and anticancer properties. Available experimental data have suggested that dietary polyphenols may be effective miRNA-modulating chemopreventive and therapeutic agents. Moreover, noninvasive detection of changes in miRNA expression in liquid biopsies opens enormous possibilities for their clinical utilization as novel prognostic and predictive biomarkers. In our published studies, we identified resveratrol-regulated miRNA profiles in prostate cancer. Resveratrol downregulated the phosphatase and tensin homolog (PTEN)-targeting members of the oncogenic miR-17 family of miRNAs, which are overexpressed in prostate cancer. We have functionally validated the miRNA-mediated ability of resveratrol and its potent analog pterostilbene to rescue the tumor suppressor activity of PTEN in vitro and in vivo. Taken together, our findings implicate the use of resveratrol and its analogs as an attractive miRNA-mediated chemopreventive and therapeutic strategy in prostate cancer and the use of circulating miRNAs as potential predictive biomarkers for clinical development.

Hydroquinone-induced FOXP3-ADAM17-Lyn-Akt-p21 signaling axis promotes malignant progression of human leukemia U937 cells

Hydroquinone (1,4-benzenediol; HQ), a major marrow metabolite of the leukemogen benzene, has been proven to evoke benzene-related hematological disorders and myelotoxicity in vitro and in vivo. The goal of the present study was to explore the role of FOXP3 in HQ-induced malignant progression of U937 human leukemia cells. U937 cells were treated with 5 μM HQ for 24 h, and the cells were re-suspended in serum-containing medium without HQ for 2 days. The same procedure was repeated three times, and the resulting U937/HQ cells were maintained in cultured medium containing 5 μM HQ. Proliferation and colony formation of U937/HQ cells were notably higher than those of U937 cells. Ten-eleven translocation methylcytosine dioxygenase-mediated demethylation of the Treg-specific demethylated region in FOXP3 gene resulted in higher FOXP3 expression in U937/HQ cells than in U937 cells. FOXP3-induced miR-183 expression reduced β-TrCP mRNA stability and suppressed β-TrCP-mediated Sp1 degradation, leading to up-regulation of Sp1 expression in U937/HQ cells. Sp1 up-regulation further increased ADAM17 and Lyn expression, and ADAM17 up-regulation stimulated Lyn activation in U937/HQ cells. Moreover, U937/HQ cells showed higher Lyn-mediated Akt activation and cytoplasmic p21 expression than U937 cells did. Abolishment of Akt activation decreased cytoplasmic p21 expression in U937/HQ cells. Suppression of FOXP3, ADAM17, and Lyn expression, as well as Akt inactivation, repressed proliferation and clonogenicity of U937/HQ cells. Together with the finding that cytoplasmic p21 shows anti-apoptotic and oncogenic activities in cancer cells, the present data suggest a role of FOXP3/ADAM17/Lyn/Akt/p21 signaling axis in HQ-induced hematological disorders.

Current state of phenolic and terpenoidal dietary factors and natural products as non-coding RNA/microRNA modulators for improved cancer therapy and prevention

The epigenetic regulation of cancer cells by small non-coding RNA molecules, the microRNAs (miRNAs), has raised particular interest in the field of oncology. These miRNAs play crucial roles concerning pathogenic properties of cancer cells and the sensitivity of cancer cells towards anticancer drugs. Certain miRNAs are responsible for an enhanced activity of drugs, while others lead to the formation of tumor resistance. In addition, miRNAs regulate survival and proliferation of cancer cells, in particular of cancer stem-like cells (CSCs), that are especially drug-resistant and, thus, cause tumor relapse in many cases. Various small molecule compounds were discovered that target miRNAs that are known to modulate tumor aggressiveness and drug resistance. This review comprises the effects of naturally occurring small molecules (phenolic compounds and terpenoids) on miRNAs involved in cancer diseases.

MicroRNAs in oral lichen planus and potential miRNA-mRNA pathogenesis with essential cytokines: a review

Oral lichen planus (OLP) is a potentially premalignant condition with unknown pathogenesis. Immune and inflammatory factors are thought to play important roles in the development of OLP, and cytokines, such as interferon (IFN)-γ and tumor necrosis factor (TNF)-α, can act as critical players in the immunopathogenesis of OLP. MicroRNAs (miRNAs) are closely correlated with cytokines in various inflammation-related diseases. In patients with OLP, miRNA-146a and miRNA-155 are increased in peripheral blood mononuclear cells, and numerous miRNAs have been shown to exhibit altered expression profiles in lesions. Although the microRNA-messenger RNA (miRNA-mRNA) network is thought to be involved in the development of OLP, in-depth studies are lacking. Here, we summarize current data on the mechanisms of action of miRNAs regulating typical cytokines in OLP, including interleukin (IL)-10, IL-17, IL-22, IFN-γ, and TNF-α, to study the genetic basis of the pathogenesis of OLP and to provide prospects of therapy.

A Comprehensive Review on the Chemotherapeutic Potential of Piceatannol for Cancer Treatment, with Mechanistic Insights

Cancer is a diverse class of diseases characterized by uncontrolled cell growth that constitutes the greatest cause of mortality and morbidity worldwide. Despite steady progress, the treatment modalities of cancer are still insufficient. Several new concepts have emerged for therapeutic intervention in malignant diseases with the goal of identifying specific targets and overcoming resistance against current cytotoxic therapies. Many studies have reported the remarkable and significant properties of dietary plant polyphenols such as curcumin, resveratrol, flavopiridol, indirubin, magnolol, piceatannol, parthenolide, epigallocatechin gallate, and cucurbitacin as anticancer agents known for their pleiotropic effects on cancer, immune cells, and inflammation. Piceatannol, an analogue and metabolite of resveratrol, is a natural stilbene commonly found in grape skins and wine. Compared to resveratrol, this molecule exhibits superior bioactivities as an inhibitor of COX-1/2 and the CSN-associated kinase. Piceatannol is thought to be a potent natural compound with many therapeutic effects, such as the prevention of hypercholesterolemia, arrhythmia, atherosclerosis, angiogenesis, and cardiovascular diseases. It also demonstrates vasorelaxation, antioxidant, and anticancer activities. This comprehensive review summarizes the current data regarding the mechanisms of action of piceatannol, its chemopreventive properties, and its possible therapeutic potential against various types of human cancer.

MicroRNA regulation of F-box proteins and its role in cancer

MicroRNAs (miRNAs) are small endogenous non-coding RNAs, which play critical roles in cancer development by suppressing gene expression at the post-transcriptional level. In general, oncogenic miRNAs are upregulated in cancer, while miRNAs that act as tumor suppressors are downregulated, leading to decreased expression of tumor suppressors and upregulated oncogene expression, respectively. F-box proteins function as the substrate-recognition components of the SKP1-CUL1-F-box (SCF)-ubiquitin ligase complex for the degradation of their protein targets by the ubiquitin-proteasome system. Therefore F-box proteins and miRNAs both negatively regulate target gene expression post-transcriptionally. Since each miRNA is capable of fine-tuning the expression of multiple target genes, multiple F-box proteins may be suppressed by the same miRNA. Meanwhile, one F-box proteins could be regulated by several miRNAs in different cancer types. In this review, we will focus on miRNA-mediated downregulation of various F-box proteins, the resulting stabilization of F-box protein substrates and the impact of these processes on human malignancies. We provide insight into how the miRNA: F-box protein axis may regulate cancer progression and metastasis. We also consider the broader role of F-box proteins in the regulation of pathways that are independent of the ubiquitin ligase complex and how that impacts on oncogenesis. The area of miRNAs and the F-box proteins that they regulate in cancer is an emerging field and will inform new strategies in cancer treatment.

p75(NTR)-dependent activation of NF-κB regulates microRNA-503 transcription and pericyte-endothelial crosstalk in diabetes after limb ischaemia

The communication between vascular endothelial cells (ECs) and pericytes in the microvasculature is fundamental for vascular growth and homeostasis; however, these processes are disrupted by diabetes. Here we show that modulation of p75(NTR) expression in ECs exposed to high glucose activates transcription of miR-503, which negatively affects pericyte function. p75(NTR) activates NF-κB to bind the miR-503 promoter and upregulate miR-503 expression in ECs. NF-κB further induces activation of Rho kinase and shedding of endothelial microparticles carrying miR-503, which transfer miR-503 from ECs to vascular pericytes. The integrin-mediated uptake of miR-503 in the recipient pericytes reduces expression of EFNB2 and VEGFA, resulting in impaired migration and proliferation. We confirm operation of the above mechanisms in mouse models of diabetes, in which EC-derived miR-503 reduces pericyte coverage of capillaries, increased permeability and impaired post-ischaemic angiogenesis in limb muscles. Collectively, our data demonstrate that miR-503 regulates pericyte-endothelial crosstalk in microvascular diabetic complications.

The microRNA-183 cluster: the family that plays together stays together

The microRNA (miR)183 cluster, which is comprised of miRs-183, -96 and -182, is also a miR family with sequence homology. Despite the strong similarity in the sequences of these miRs, minute differences in their seed sequences result in both overlapping and distinct messenger RNA targets, which are often within the same pathway. These miRs have tightly synchronized expression during development and are required for maturation of sensory organs. In comparison to their defined role in normal development, the miR-183 family is frequently highly expressed in a variety of non-sensory diseases, including cancer, neurological and auto-immune disorders. Here, we discuss the conservation of the miR-183 cluster and the functional role of this miR family in normal development and diseases. We also describe the regulation of vital cellular pathways by coordinated expression of these miR siblings. This comprehensive review sheds light on the likely reasons why the genomic organization and seeming redundancy of the miR-183 family cluster was conserved through 600 million years of evolution.

FOXP3 Controls an miR-146/NF-κB Negative Feedback Loop That Inhibits Apoptosis in Breast Cancer Cells

FOXP3 functions not only as the master regulator in regulatory T cells, but also as an X-linked tumor suppressor. The tumor-suppressive activity of FOXP3 has been observed in tumor initiation, but its role during tumor progression remains controversial. Moreover, the mechanism of FOXP3-mediated tumor-suppressive activity remains largely unknown. Using chromatin immunoprecipitation (ChIP) sequencing, we identified a series of potential FOXP3-targeted miRNAs in MCF7 cells. Notably, FOXP3 significantly induced the expression of miR-146a/b. In vitro, FOXP3-induced miR-146a/b prevented tumor cell proliferation and enhanced apoptosis. Functional analyses in vitro and in vivo revealed that FOXP3-induced miR-146a/b negatively regulates NF-κB activation by inhibiting the expression of IRAK1 and TRAF6. In ChIP assays, FOXP3 directly bound the promoter region of miR-146a but not of miR-146b, and FOXP3 interacted directly with NF-κB p65 to regulate an miR-146-NF-κB negative feedback regulation loop in normal breast epithelial and tumor cells, as demonstrated with luciferase reporter assays. Although FOXP3 significantly inhibited breast tumor growth and migration in vitro and metastasis in vivo, FOXP3-induced miR-146a/b contributed only to the inhibition of breast tumor growth. These data suggest that miR-146a/b contributes to FOXP3-mediated tumor suppression during tumor growth by triggering apoptosis. The identification of a FOXP3-miR-146-NF-κB axis provides an underlying mechanism for disruption of miR-146 family member expression and constitutive NF-κB activation in breast cancer cells. Linking the tumor suppressor function of FOXP3 to NF-κB activation reveals a potential therapeutic approach for cancers with FOXP3 defects.

FOXP3-miR-146-NF-κB Axis and Therapy for Precancerous Lesions in Prostate

The tumor-suppressive activity of FOXP3 has been observed in tumor initiation, but the underlying mechanism still remains largely unknown. Here, we identified a FOXP3-microRNA-146 (miR-146)-NF-κB axis in vitro and in vivo in prostate cancer cells. We observed that FOXP3 dramatically induced the expression of miR-146a/b, which contributed to transcriptional inhibition of IRAK1 and TRAF6, in prostate cancer cell lines. Tissue-specific deletion of Foxp3 in mouse prostate caused a significant reduction of miR-146a and upregulation of NF-κB activation. In addition, prostatic intraepithelial neoplasia lesions were observed in miR-146a-mutant mice as well as in Foxp3-mutant mice. Notably, the NF-κB inhibitor bortezomib inhibited cell proliferation and induced apoptosis in prostate epithelial cells, attenuating prostatic intraepithelial neoplasia formation in Foxp3-mutant mice. Our data suggest that the FOXP3-miR-146-NF-κB axis has a functional role during tumor initiation in prostate cancer. Targeting the miR-146-NF-κB axis may provide a new therapeutic approach for prostate cancers with FOXP3 defects.

Therapeutic microRNAs targeting the NF-kappa B signaling circuits of cancers

MicroRNAs (miRNAs) not only directly regulate NF-κB expression, but also up- or down-regulate NF-κB activity via upstream and downstream signaling pathways of NF-κB. In many cancer cells, miRNA expressions are altered accompanied with an elevation of NF-κB activity, which often plays a role in promoting cancer development and progression as well as hindering the effectiveness of chemo and radiation therapies. Thus NF-κB-targeting miRNAs have been identified and characterized as potential therapeutics for cancer treatment and sensitizers of chemo and radiotherapies. However, due to cross-targeting and instability of miRNAs, some limitations of using miRNA as cancer therapeutics still exist. In this review, the mechanisms for miRNA-mediated alteration of NF-κB expression and activation in different types of cancers will be discussed. The results of therapeutic use of NF-κB-targeting miRNA for cancer treatment will be examined. Some limitations, challenges and potential strategies in future development of miRNA as cancer therapeutics are also assessed.

Piceatannol promotes apoptosis via up-regulation of microRNA-129 expression in colorectal cancer cell lines

Piceatannol, a naturally occurring analog of resveratrol, has been confirmed as an antitumor agent by inhibiting proliferation, migration, and metastasis in diverse cancer. However, the effect and mechanisms of piceatannol on colorectal cancer (CRC) have not been well understood. This study aimed to test whether piceatannol could inhibit growth of CRC cells and reveal its underlying molecular mechanism. MTT assay was used to detect the cell viability in HCT116 and HT29 cells. Flow cytometry analysis was employed to measure apoptosis of CRC cells. Bcl-2, Bax and caspase-3 levels were analyzed by Western blot and miR-129 levels were determined by real-time RT-PCR. Our study showed that piceatannol inhibited HCT116 and HT29 cells growth in a concentration- and time-dependent manner. Piceatannol induced apoptosis by promoting expression of miR-129, and then inhibiting expression of Bcl-2, an known target for miR-129. Moreover, knock down of miR-129 could reverse the reduction of cell viability induced by piceatannol in HCT116 and HT29 cells. Taken together, our study unraveled the ability of piceatannol to suppress colorectal cancer growth and elucidated the participation of miR-129 in the anti-cancer action of piceatannol. Our findings suggest that piceatannol can be considered to be a promising anticancer agent for CRC.

Taiwan cobra phospholipase A2 suppresses ERK-mediated ADAM17 maturation, thus reducing secreted TNF-α production in human leukemia U937 cells

The goal of this study was to explore the signaling pathway regulating the processing of proADAM17 into ADAM17 in Taiwan cobra phospholipase A2 (PLA2)-treated human leukemia U937 cells. PLA2 induced reactive oxygen species (ROS)-elicited p38 MAPK activation and ERK inactivation in U937 cells. Catalytically inactive bromophenacylated PLA2 (BPB-PLA2) and PLA2 mutants evoked Ca(2+)-mediated p38 MAPK activation, and the level of phosphorylated ERK remained unchanged. PLA2 treatment reduced mature ADAM17 expression and secreted TNF-α (sTNF-α) production. Co-treatment of SB202190 (p38 MAPK inhibitor) and catalytically inactive PLA2 increased ERK phosphorylation, ADAM17 maturation and sTNF-α production. Nevertheless, mRNA levels of ADAM17 and TNF-α were insignificantly altered after PLA2 and SB202190/BPB-PLA2 treatment. ADAM17 activity assay and knock-down of ADAM17 revealed that ADAM17 was involved in sTNF-α production. Restoration of ERK activation increased the processing of proADAM17 into ADAM17 in PLA2-treated cells, while inactivation of ERK reduced ADAM17 maturation in untreated and SB202190/BPB-PLA2-treated cells. Removal of cell surface heparan sulfate abrogated PLA2 and SB202190/BPB-PLA2 effect on ADAM17 maturation. Taken together, the present data reveal that PLA2 suppresses ERK-mediated ADAM17 maturation, thus reducing sTNF-α production in U937 cells. Moreover, the binding with heparan sulfate is crucial for the PLA2 effect.

Piceatannol: a potential futuristic natural stilbene as fetal haemoglobin inducer

Beta thalassaemia is an autosomal recessive inherited blood disorder which results in abnormal formation of Haemoglobin molecule and ineffective erythropoiesis. Patients need to be dependent on habitual blood transfusion and on unaffordable exorbitant therapies for continued existence. It has been hypothesized that if the level of foetal Haemoglobin increases, it compensates the need of adult Haemoglobin and hence, ameliorates clinical symptoms associated with beta thalassaemia major. Illation from previous studies has proved that reactivation of foetal Haemoglobin with the aid of natural compounds is a better alternative therapy for patients of beta thalassaemia because of its cost effectiveness and occurrence in natural eatables. Piceatannol, a naturally occurring stilbene, is less studied compound in comparison to resveratrol, but it shows a wide range of biological activities. This article has mainly focused on piceatannol and its application as a foetal Haemoglobin inducer in future.