FRA1:c-JUN:HDAC1 complex down-regulates filaggrin expression upon TNFα and IFNγ stimulation in keratinocytes.

Filaggrin (FLG), an essential structural protein for skin barrier function, is down-regulated under chronic inflammatory conditions, leading to disruption of the skin barrier. However, the detailed molecular mechanisms of how FLG changes in the context of chronic inflammation are poorly understood. Here, we identified the molecular mechanisms by which inflammatory cytokines inhibit FLG expression in the skin. We found that the AP1 response element within the -343/+25 of the FLG promoter was necessary for TNFα + IFNγ-induced down-regulation of FLG promoter activity. Using DNA affinity precipitation assay, we observed that AP1 subunit composition binding to the FLG promoter was altered from c-FOS:c-JUN (at the early time) to FRA1:c-JUN (at the late time) in response to TNFα + IFNγ stimulation. Knockdown of FRA1 or c-JUN abrogated TNFα + IFNγ-induced FLG suppression. Histone deacetylase (HDAC) 1 interacted with FRA1:c-JUN under TNFα + IFNγ stimulation. Knockdown of HDAC1 abrogated the inhibitory effect of TNFα + IFNγ on FLG expression. The altered expression of FLG, FRA1, c-JUN, and HDAC1 was confirmed in mouse models of 2,4-dinitrochlorobenzene-induced atopic dermatitis and imiquimod-induced psoriasis. Thus, the current study demonstrates that TNFα + IFNγ stimulation suppresses FLG expression by promoting the FRA1:c-JUN:HDAC1 complex. This study provides insight into future therapeutic strategies targeting the FRA1:c-JUN:HDAC1 complex to restore impaired FLG expression in chronic skin inflammation.

Pyrazolines inhibiting the activity of the early growth response-1 DNA-binding domain.

To identify compounds inhibiting the activity of the Early Growth Response (EGR)-1 DNA-binding domain, thirty-seven pyrazolines were prepared and their EGR-1 DNA-binding activities were measured. Pharmacophores were derived based on quantitative structure-activity relationship calculations. As compound 2, 1-(5-(4-methoxyphenyl)-4,5-dihydro-1H-pyrazol-3-yl)naphthalen-2-ol, showed the best inhibitory effects against the activity of the EGR-1 DNA-binding domain, the binding mode between compound 2 and EGR-1 was elucidated using in silico docking. The pharmacophores were matched to the binding modes. Electrophoretic mobility shift assays confirmed that compound 2 dose-dependently inhibited TNFα-induced EGR-1-DNA complex formation in HaCaT cells. Reverse transcription-polymerase chain reaction demonstrated that compound 2 effectively reduced the mRNA expression of EGR-1-regulated inflammatory genes, including thymic stromal lymphopoietin (TSLP), interleukin (IL)-1ß, IL-6, and IL-31, in TNFα-stimulated HaCaT cells. Therefore, compound 2 could be developed as an agent that inhibits the activity of the EGR-1 DNA-binding domain.

Design, synthesis, and biological evaluation of 2-(2-oxoindolin-3-ylidene)hydrazinecarbothioamides as a potential EGR-1 inhibitor for targeted therapy of atopic dermatitis.

Atopic dermatitis is a chronic inflammatory skin disease characterized by intense itching and frequent skin barrier dysfunctions. EGR-1 is a transcription factor that aggravates the pathogenesis of atopic dermatitis by promoting the production of various inflammatory cytokines. Three 2-(2-oxoindolin-3-ylidene)hydrazinecarbothioamides (IT21, IT23, and IT25) were identified as novel inhibitors of EGR-1 DNA-binding activity. In silico docking experiments were performed to elucidate the binding conditions of the EGR-1 zinc-finger (ZnF) DNA-binding domain. Electrophoretic mobility shift assays confirmed the targeted binding effect on the EGR-1 ZnF DNA-binding domain, leading to dose-dependent dissociation of the EGR-1-DNA complex. At the functional cellular level, IT21, IT23, and IT25 effectively reduced mRNA expression of TNFα-induced EGR-1-regulated inflammatory genes, particularly in HaCaT keratinocytes inflamed by TNFα. In the in vivo efficacy study, IT21, IT23, and IT25 demonstrated the potential to alleviate atopic dermatitis-like skin lesions in the ear skin of BALB/c mice. These findings suggest that targeting the EGR-1 ZnF DNA-binding domain with 2-(2-oxoindolin-3-ylidene)hydrazinecarbothioamide derivatives (IT21, IT23, and IT25) could serve as lead compounds for the development of potential therapeutic agents against inflammatory skin disorders, including atopic dermatitis.

Design, synthesis, and biological activities of 3-((4,6-diphenylpyrimidin-2-ylamino)methylene)-2,3-dihydrochromen-4-ones.

Novel (Z)-3-((4,6-diphenylpyrimidin-2-ylamino)methylene)-2,3-dihydrochromen-4-one derivatives were designed and synthesized to find chemotherapeutic agents. Derivative 9 was selected based on its clonogenicity against cancer cells and synthetic yield for further biological experiments. It showed decreases in aurora kinase A, B, and C phosphorylation from western blot analysis. Derivative 9 upregulated the expression of G1 cell cycle inhibitory proteins including p21 and p27, and G1 progressive cyclin D1, and downregulated G1-to-S progressive cyclins, resulting in cell cycle arrest at the G1/S boundary. It stimulated the cleavage of caspase-9, -3, -7, and poly (ADP-ribose) polymerase, resulting in triggering apoptosis through a caspase-dependent pathway. In addition, derivative 9 inhibited in vivo tumor growth in a syngeneic tumor implantation mouse model. The findings of this study suggest that derivative 9 can be considered as a lead compound for chemotherapeutic agents.

Saikosaponin A and Saikosaponin C Reduce TNF-α-Induced TSLP Expression through Inhibition of MAPK-Mediated EGR1 Expression in HaCaT Keratinocytes.

Atopic dermatitis (AD) is one of the most common chronic inflammatory skin diseases worldwide, characterized by intense pruritus and eczematous lesions. Aberrant expression of thymic stromal lymphopoietin (TSLP) in keratinocytes is associated with the pathogenesis of AD and is considered a therapeutic target for the treatment of this disease. Saikosaponin A (SSA) and saikosaponin C (SSC), identified from Radix Bupleuri, exert anti-inflammatory effects. However, the topical effects of SSA and SSC on chronic inflammatory skin diseases are unclear. In this study, we investigated the effects of SSA and SSC on TSLP suppression in an AD-like inflammatory environment. We observed that SSA and SSC suppressed tumor necrosis factor-α-induced TSLP expression by downregulating the expression of the transcription factor early growth response 1 (EGR1) via inhibition of the extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase 1/2, and p38 mitogen-activated protein kinase pathways. We also confirmed that topical application of SSA or SSC reduced AD-like skin lesions in BALB/c mice challenged with 2,4-dinitrochlorobenzene. Our findings suggest that suppression of EGR1-regulated TSLP expression in keratinocytes might be attributable to the anti-inflammatory effects of SSA and SSC in AD-like skin lesions.

ß-Caryophyllene Ameliorates 2,4-Dinitrochlorobenzene-Induced Atopic Dermatitis through the Downregulation of Mitogen-Activated Protein Kinase/EGR1/TSLP Signaling Axis.

Atopic dermatitis (AD) is one of the most common inflammatory skin diseases accompanied by severe itching. ß-caryophyllene (BCP), which displays anti-inflammatory activity, is a natural agonist of cannabinoid receptor 2. However, the therapeutic effects of BCP on atopic dermatitis (AD) remain poorly understood. The current study aimed to evaluate the topical therapeutic efficacy of BCP in an AD-like mouse model. Thymic Stromal Lymphopoietin (TSLP) is a keratinocyte-derived cytokine that drives AD pathogenesis. This study also investigated the effect of BCP on the interleukin 4 (IL-4)-induced expression of TSLP in HaCaT keratinocytes. We found that the topical application of BCP alleviated AD-like skin inflammation and inhibited the infiltration of proinflammatory cells into skin lesions. Moreover, the topical application of BCP reduced EGR1 (Early Growth Response 1) and TSLP expression in AD-like skin lesions. We also found that BCP inhibited IL-4-induced TSLP expression by downregulating mitogen-activated protein kinase (MAPK)-mediated EGR1 expression in HaCaT keratinocytes. These findings demonstrate that BCP ameliorates DNCB-induced AD-like skin lesions through the downregulation of the MAPK/EGR1/TSLP signaling axis. BCP may be applicable for developing topical therapeutic agents for chronic skin inflammatory diseases, such as AD.

The Natural Janus Kinase Inhibitor Agerarin Downregulates Interleukin-4-Induced PER2 Expression in HaCaT Keratinocytes.

The circadian clock system is closely associated with inflammatory responses. Dysregulation of the circadian clock genes in the skin impairs the skin barrier function and affects the pathophysiology of atopic dermatitis. Interleukin 4 (IL-4) is a proinflammatory cytokine derived from T-helper type 2 cells; it plays a critical role in the pathogenesis of atopic dermatitis. Agerarin (6,7-dimethoxy-2,2-dimethyl-2H-chromene) is a natural JAK1/2/3 inhibitor isolated from Ageratum houstonianum that has a protective effect on the epidermal skin barrier. However, it remains unclear whether agerarin affects the circadian clock system. The aim of this study is to investigate the effect of agerarin on IL-4-induced PER2 gene expression in human keratinocytes through reverse transcription (RT)-PCR, quantitative real-time PCR (qPCR), immunoblotting, immunofluorescence microscopic analysis, and real-time bioluminescence analysis. We found that agerarin reduced IL-4-induced PER2 mRNA expression by suppressing the JAK-STAT3 pathway. In addition, real-time bioluminescence analysis in PER2:luc2p promoter-reporter cells revealed that agerarin restored the oscillatory rhythmicity of PER2 promoter activity altered by IL-4. These findings suggest that agerarin may be useful as a cosmeceutical agent against inflammatory skin conditions associated with disrupted circadian rhythms, such as atopic dermatitis.

Inhibition of EGR-1-dependent MMP1 transcription by ethanol extract of Ageratum houstonianum in HaCaT keratinocytes.

Matrix metalloproteinase 1 (MMP-1) initiates the breakdown of matrix networks by cleaving fibrillar collagen during the pathophysiological progression of skin aging. Ageratum houstonianum ethanol extract (AHE) has been used as a traditional herbal medicine to treat external wounds and skin diseases. However, the mechanism of action underlying A. houstonianum-mediated modulation of skin aging has not been investigated. In this study, we evaluated the effect of AHE on MMP-1 expression in HaCaT keratinocytes. Gene expression was analyzed by Reverse transcription-PCR (RT-PCR), Quantitative real-time PCR (Q-PCR), gene promoter-reporter assay, and immunoblotting. We found that AHE abrogated TNFα-induced MMP1 expression at the transcriptional level via the suppression of ERK1/2 mitogen-activated protein kinase (MAPK)-mediated Early Growth Response 1 (EGR1) expression. We also demonstrated that ß-caryophyllene, a cannabinoid receptor 2 (CB2) agonist, is a functional component of the AHE that inhibits TNFα-induced EGR-1 and MMP1 expression. AHE exerts inhibitory activity on TNFα-induced MMP1 expression at the transcription level through EGR-1 downregulation in keratinocytes. ß-Caryophyllene is a bioactive ingredient of AHE that is responsible for the inhibition of TNFα-induced EGR1 expression. ß-Caryophyllene can be used as a potential agent to prevent inflammation-induced skin aging.

Chrysin Inhibits TNFα-Induced TSLP Expression through Downregulation of EGR1 Expression in Keratinocytes.

Thymic stromal lymphopoietin (TSLP) is an epithelial cell-derived cytokine that acts as a critical mediator in the pathogenesis of atopic dermatitis (AD). Various therapeutic agents that prevent TSLP function can efficiently relieve the clinical symptoms of AD. However, the downregulation of TSLP expression by therapeutic agents remains poorly understood. In this study, we investigated the mode of action of chrysin in TSLP suppression in an AD-like inflammatory environment. We observed that the transcription factor early growth response (EGR1) contributed to the tumor necrosis factor alpha (TNFα)-induced transcription of TSLP. Chrysin attenuated TNFα-induced TSLP expression by downregulating EGR1 expression in HaCaT keratinocytes. We also showed that the oral administration of chrysin improved AD-like skin lesions in the ear and neck of BALB/c mice challenged with 2,4-dinitrochlorobenzene. We also showed that chrysin suppressed the expression of EGR1 and TSLP by inhibiting the extracellular signal-regulated kinase (ERK) 1/2 and c-Jun N-terminal kinase (JNK) 1/2 mitogen-activated protein kinase pathways. Collectively, the findings of this study suggest that chrysin improves AD-like skin lesions, at least in part, through the downregulation of the ERK1/2 or JNK1/2-EGR1-TSLP signaling axis in keratinocytes.

Chrysin Inhibits NF-κB-Dependent CCL5 Transcription by Targeting IκB Kinase in the Atopic Dermatitis-Like Inflammatory Microenvironment.

Chrysin (5,7-dihydroxyflavone) is a natural polyphenolic compound that induces an anti-inflammatory response. In this study, we investigated the molecular mechanism underlying the chrysin-induced suppression of C-C motif chemokine ligand 5 (CCL5) gene expression in atopic dermatitis (AD)-like inflammatory microenvironment. We showed that chrysin inhibited CCL5 expression at the transcriptional level through the suppression of nuclear factor kappa B (NF-κB) in the inflammatory environment. Chrysin could bind to the ATP-binding pocket of the inhibitor of κB (IκB) kinase (IKK) and, subsequently, prevent IκB degradation and NF-κB activation. The clinical efficacy of chrysin in targeting IKK was evaluated in 2,4-dinitrochlorobenzene-induced skin lesions in BALB/c mice. Our results suggested that chrysin prevented CCL5 expression by targeting IKK to reduce the infiltration of mast cells to the inflammatory sites and at least partially attenuate the inflammatory responses. These findings suggested that chrysin might be useful as a platform for the design and synthesis of small-molecule IKK-targeting drugs for the treatment of chronic inflammatory diseases, such as AD.

Chrysoeriol Prevents TNFα-Induced CYP19 Gene Expression via EGR-1 Downregulation in MCF7 Breast Cancer Cells.

Estrogen overproduction is closely associated with the development of estrogen receptor-positive breast cancer. Aromatase, encoded by the cytochrome P450 19 (CYP19) gene, regulates estrogen biosynthesis. This study aimed to identify active flavones that inhibit CYP19 expression and to explore the underlying mechanisms. CYP19 expression was evaluated using reverse transcription PCR, quantitative real-time PCR, and immunoblot analysis. The role of transcription factor early growth response gene 1 (EGR-1) in CYP19 expression was assessed using the short-hairpin RNA (shRNA)-mediated knockdown of EGR-1 expression in estrogen receptor-positive MCF-7 breast cancer cells. We screened 39 flavonoids containing 26 flavones and 13 flavanones using the EGR1 promoter reporter activity assay and observed that chrysoeriol exerted the highest inhibitory activity on tumor necrosis factor alpha (TNFα)-induced EGR-1 expression. We further characterized and demonstrated that chrysoeriol inhibits TNFα-induced CYP19 expression through inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2)-mediated EGR-1 expression. Chrysoeriol may be beneficial as a dietary supplement for the prevention of estrogen receptor-positive breast cancer, or as a chemotherapeutic adjuvant in the treatment of this condition.

A Novel Synthetic Compound (E)-5-((4-oxo-4H-chromen-3-yl)methyleneamino)-1-phenyl-1H-pyrazole-4-carbonitrile Inhibits TNFα-Induced MMP9 Expression via EGR-1 Downregulation in MDA-MB-231 Human Breast Cancer Cells.

Breast cancer is a common malignancy among women worldwide. Gelatinases such as matrix metallopeptidase 2 (MMP2) and MMP9 play crucial roles in cancer cell migration, invasion, and metastasis. To develop a novel platform compound, we synthesized a flavonoid derivative, (E)-5-((4-oxo-4H-chromen-3-yl)methyleneamino)-1-phenyl-1H-pyrazole-4-carbonitrile (named DK4023) and characterized its inhibitory effects on the motility and MMP2 and MMP9 expression of highly metastatic MDA-MB-231 breast cancer cells. We found that DK4023 inhibited tumor necrosis factor alpha (TNFα)-induced motility and F-actin formation of MDA-MB-231 cells. DK4023 also suppressed the TNFα-induced mRNA expression of MMP9 through the downregulation of the TNFα-extracellular signal-regulated kinase (ERK)/early growth response 1 (EGR-1) signaling axis. These results suggest that DK4023 could serve as a potential platform compound for the development of novel chemopreventive/chemotherapeutic agents against invasive breast cancer.

2,4­Di­tert­butylphenol, a potential HDAC6 inhibitor, induces senescence and mitotic catastrophe in human gastric adenocarcinoma AGS cells.

The natural product 2,4­di­tert­butylphenol (DTBP) has a wide spectrum of biological functions, including anticancer activities, although the underlying mechanisms are poorly understood. Here, we found that DTBP induces senescence in human gastric adenocarcinoma AGS cells as evidenced by upregulation of p21 and Rb and increased ß­galactosidase activity. DTBP also induces mitotic catastrophe and generates multinucleated cells, which is accompanied by an increase in the proportion of polymerized tubulin, possibly caused by inhibition of HDAC6 enzyme activity. In silico docking analysis showed that DTBP docked at the entrance of the ligand-binding pocket of the HDAC6 enzyme. Accordingly, DTBP represents a promising lead structure for the development of HDAC6 inhibitors, with an improvement in specificity conferred by modification of the cap group. We propose for the first time that the underlying mechanism of the anticancer activity of DTBP is attributed to inhibition of HDAC6 activity.

Design, synthesis, and biological activities of 1-aryl-(3-(2-styryl)phenyl)prop-2-en-1-ones.

A moderate elevation in reactive oxygen species (ROS) levels can generally be controlled in normal cells, but may lead to death of cancer cells as the ROS level in cancer cells is already elevated. Therefore, a ROS-generating compound can act as a selective chemotherapeutic agent for cancer cells that does not affect normal cells. In our previous study, a compound containing a Michael acceptor was selectively cytotoxic to cancer cells without affecting normal cells; therefore, we designed and synthesized 26 compounds containing a Michael acceptor. Their cytotoxicities against HCT116 human colon cancer cell lines were measured by using a clonogenic long-term survival assay. To derive the structural conditions required to obtain stronger cytotoxicity against cancer cells, the relationships between the half-maximal cell growth inhibitory concentration values of the synthesized compounds and their physicochemical properties were evaluated by Comparative Molecular Field Analysis and Comparative Molecular Similarity Indices Analysis. It was confirmed that the compound with the best half-maximal cell growth inhibitory concentration triggered apoptosis through ROS generation, which then led to stimulation of the caspase pathway.

A Computational-Based Approach to Identify Estrogen Receptor α/ß Heterodimer Selective Ligands.

The biologic effects of estrogens are transduced by two estrogen receptors (ERs), ERα and ERß, which function in dimer forms. The ERα/α homodimer promotes and the ERß/ß inhibits estrogen-dependent growth of mammary epithelial cells; the functions of ERα/ß heterodimers remain elusive. Using compounds that promote ERα/ß heterodimerization, we have previously shown that ERα/ß heterodimers appeared to inhibit tumor cell growth and migration in vitro. Further dissection of ERα/ß heterodimer functions was hampered by the lack of ERα/ß heterodimer-specific ligands. Herein, we report a multistep workflow to identify the selective ERα/ß heterodimer-inducing compound. Phytoestrogenic compounds were first screened for ER transcriptional activity using reporter assays and ER dimerization preference using a bioluminescence resonance energy transfer assay. The top hits were subjected to in silico modeling to identify the pharmacophore that confers ERα/ß heterodimer specificity. The pharmacophore encompassing seven features that are potentially important for the formation of the ERα/ß heterodimer was retrieved and subsequently used for virtual screening of large chemical libraries. Four chemical compounds were identified that selectively induce ERα/ß heterodimers over their respective homodimers. Such ligands will become unique tools to reveal the functional insights of ERα/ß heterodimers.

The synthetic chalcone derivative 2-hydroxy-3',5,5'-trimethoxychalcone induces unfolded protein response-mediated apoptosis in A549 lung cancer cells.

The synthetic chalcone derivative 2-hydroxy-3',5,5'-trimenthoxyochalcone (named DK-139) exhibits anti-inflammatory and anti-tumor invasion properties. However, effects of DK-139 on tumor cell growth remain unknown. In the present study, we evaluated the inhibitory activity of DK-139 against human lung cancer cells. Treatment with DK-139 inhibited clonogenicity in various lung cancers and stimulated the caspase cascade, leading to the apoptosis of A549 lung cancer cells. To investigate the mode of action of DK-139-induced apoptosis, we analyzed the effect of DK-139 on the endoplasmic reticulum (ER) stress response. DK-139 increased expression of ER stress sensors, including p-PERK, GRP78/BiP, and IRE1α. IRE1α-regulated XBP-1 mRNA splicing and PERK-induced ATF4 expression was also upregulated following DK-139 treatment. In addition, expression levels of the pro-apoptotic transcription factor CHOP and its downstream target Bim, which is involved in mitochondria-mediated apoptosis, were increased by DK-139 treatment. These results suggest that DK-139 triggers caspase-mediated apoptosis via the ER stress-activated unfolded protein response (UPR) pathway. We propose that the synthetic chalcone derivative DK-139 may be used as a potential agent for the prevention and/or treatment of human lung cancer.

Inhibitory Effect of Alisma canaliculatum Ethanolic Extract on NF-κB-Dependent CXCR3 and CXCL10 Expression in TNFα-Exposed MDA-MB-231 Breast Cancer Cells.

CXC motif chemokine ligand 10 (CXCL10) and its receptor CXC motif chemokine receptor 3 (CXCR3), play important roles in the motility of breast cancer cells. Alisma canaliculatum is a herb that has been used as a traditional medicine for thousands of years in Korea and China. Whether A. canaliculatum inhibits the motility of metastatic breast cancer cells is not clear yet. In this study, we show that A. canaliculatum ethanolic extract (ACE) prevented tumor necrosis factor-alpha (TNFα)-induced migration of MDA-MB-231 cells. ACE significantly attenuated TNFα-induced upregulation of CXCL10 and CXCR3 expression at the gene promoter level. Mechanistically, ACE inhibits TNFα-induced phosphorylation of inhibitor of κB (IκB) kinase (IKK), IκB and p65/RelA, leading to the suppression of nuclear translocation of p65/RelA nuclear factor kappa-B (NF-κB). Also, ACE inhibited NF-κB-dependent CXCR3 and CXCL10 promoter activities. These results suggest that ACE abrogates TNFα-induced migration of MDA-MB-231 breast cancer cells through down-regulation of IKK-NF-κB-dependent CXCR3 and CXCL10 expression. Our results suggest that ACE has potential as a herbal supplement for the inhibition of breast cancer metastasis.

A Novel Synthetic Material, BMM, Accelerates Wound Repair by Stimulating Re-Epithelialization and Fibroblast Activation.

Cutaneous wound repair is an intricate process whereby the skin reprograms itself after injury. In the mid-phase of wound repair, the proliferation, migration, and differentiation of cells are the major mechanisms to lead remodeling. We investigated the effect of BMM ((1E,2E)-1,2-bis((6-bromo-2H-chromen-3-yl)methylene)hydrazine), a novel synthetic material, on the migration and viability of keratinocytes or fibroblasts using the in vitro scratch woundhealing, electric cell-substrate imedance sensing (ECIS), invasion, and MTT assays. Cell migration-related factors were analyzed using western blot, and we found that treatment with BMM stimulated the EMT pathway and focal adhesion kinase (FAK)/Src signaling. Differentiation of HaCaT keratinocyte and fibroblast cells was also stimulated by BMM and specifically, NOX2/4 contributed to the activation of fibroblasts for wound healing. Furthermore, BMM treated HaCaT keratinocyte and fibroblast-co-cultured cells increased migration and differentiation. TGF-ß and Cyr61 were also secreted to a greater extent than in single cultured cells. In vivo experiments showed that treatment with BMM promotes wound closure by promoting re-epithelialization. In this study, we demonstrated that a novel synthetic material, BMM, is capable of promoting wound healing via the stimulation of re-epithelialization in the epidermis and the activation of fibroblasts in the dermis, in particular, via the acceleration of the interaction between the epidermis and dermis.

Downregulation of α-Melanocyte-Stimulating Hormone-Induced Activation of the Pax3-MITF-Tyrosinase Axis by Sorghum Ethanolic Extract in B16F10 Melanoma Cells.

Ultraviolet irradiation-induced hyperpigmentation of the skin is associated with excessive melanin production in melanocytes. Tyrosinase (TYR) is a key enzyme catalyzing the rate-limiting step in melanogenesis. TYR expression is controlled by microphthalmia-associated transcription factor (MITF) expression. Sorghum is a cereal crop widely used in a variety of foods worldwide. Sorghum contains many bioactive compounds and is beneficial to human health. However, the effects of sorghum in anti-melanogenesis have not been well characterized. In this study, the biological activity of sorghum ethanolic extract (SEE) on α-melanocyte-stimulating hormone (α-MSH)-induced TYR expression was evaluated in B16F10 melanoma cells. SEE attenuated α-MSH-induced TYR gene promoter activity through the downregulation of the transcription factor MITF. We found that paired box gene 3 (Pax3) contributes to the maximal induction of MITF gene promoter activity. Further analysis demonstrated that SEE inhibited α-MSH-induced Pax3 expression. The collective results indicate that SEE attenuates α-MSH-induced TYR expression through the suppression of Pax3-mediated MITF gene promoter activity. Targeting the Pax3-MITF axis pathway could be considered a potential strategy to increase the efficacy of anti-melanogenesis.

Inhibitory Effect of Synthetic Flavone Derivatives on Pan-Aurora Kinases: Induction of G2/M Cell-Cycle Arrest and Apoptosis in HCT116 Human Colon Cancer Cells.

Members of the aurora kinase family are Ser/Thr kinases involved in regulating mitosis. Multiple promising clinical trials to target aurora kinases are in development. To discover flavones showing growth inhibitory effects on cancer cells, 36 flavone derivatives were prepared, and their cytotoxicity was measured using a long-term clonogenic survival assay. Their half-maximal growth inhibitory effects against HCT116 human colon cancer cells were observed at the sub-micromolar level. Pharmacophores were derived based on three-dimensional quantitative structure⁻activity calculations. Because plant-derived flavones inhibit aurora kinase B, we selected 5-methoxy-2-(2-methoxynaphthalen-1-yl)-4H-chromen-4-one (derivative 31), which showed the best half-maximal cell growth inhibitory effect, and tested whether it can inhibit aurora kinases in HCT116 colon cancer cells. We found that derivative 31 inhibited the phosphorylation of aurora kinases A, aurora kinases B and aurora kinases C, suggesting that derivative 31 is a potential pan-aurora kinase inhibitor. The results of our analysis of the binding modes between derivative 31 and aurora A and aurora B kinases using in-silico docking were consistent with the pharmacophores proposed in this study.