MED28 regulates MEK1-dependent cellular migration in human breast cancer cells

Apigenin Suppresses MED28-Mediated Cell Growth in Human Liver Cancer Cells

Flavonoids exhibit health-promoting benefits against multiple chronic diseases, including cancer. Apigenin (4',5,7-trihydroxyflavone), one flavonoid present in fruits and vegetables, is potentially applicable to chemoprevention. Despite considerable progress in the therapeutic regimen of liver cancer, its prognosis remains poor. MED28, a Mediator subunit for transcriptional activation, is implicated in the development of several types of malignancy; however, its role in liver cancer is unknown at present. In liver cancer, the AKT/mammalian target of rapamycin (mTOR) is one major pathway involved in the oncogenic process. The aim of this study is to investigate the role of apigenin and MED28 in AKT/mTOR signaling in liver cancer. We first identified a connectivity score of 92.77 between apigenin treatment and MED28 knockdown in several cancer cell lines using CLUE, a cloud-based software platform to assess connectivity among compounds and genetic perturbagens. Higher expression of MED28 predicted a poorer survival prognosis; MED28 expression in liver cancer tissue was significantly higher than that of normal tissue, and it was positively correlated with tumor stage and grade in The Cancer Genome Atlas Liver Cancer (TCGA-LIHC) data set. Knockdown of MED28 induced cell cycle arrest and suppressed the AKT/mTOR signaling in two human liver cancer cell lines, HepG2 and Huh 7, accompanied by less lipid accumulation and lower expression and nuclear localization of sterol regulatory element binding protein 1 (SREBP1). Apigenin inhibited the expression of MED28, and the effect of apigenin mimicked that of the MED28 knockdown. On the other hand, the AKT/mTOR signaling was upregulated when MED28 was overexpressed. These data indicated that MED28 was associated with the survival prognosis and the progression of liver cancer by regulating AKT/mTOR signaling and apigenin appeared to inhibit cell growth through MED28-mediated mTOR signaling, which may be applicable as an adjuvant of chemotherapy or chemoprevention in liver cancer.

β-eudesmol inhibits cell proliferation and induces ferroptosis via regulating MAPK signaling pathway in breast cancer

The aim of this study was to explore the influences and underlying mechanisms of β-eudesmol on breast cancer (BC). Different concentrations of β-eudesmol (0, 10, 20, and 40 μM) were taken to treat BC cells. Cell Counting Kit-8, colony formation assay, and flow cytometry were performed to evaluate the influences of β-eudesmol on cell viability, proliferation, and apoptosis. To assess the influences of β-eudesmol on cell ferroptosis, the change of ROS, SOD, MDA, and intracellular iron and Fe2+ were determined. The protein changes of apoptosis, ferroptosis, and MAPK pathway (Bcl-2, Bax, cleaved caspase-3, SLC7A11, GPX4, SLC40A1, Transferrin, MEK1, and ERK1/2) were checked utilizing Western blot. In a concentration-dependent manner, β-eudesmol restrained cell viability and proliferation. β-eudesmol promoted cell apoptosis, as evidenced by the decline level of Bcl-2 and the raised level of Bax and cleaved caspase-3. β-eudesmol enhanced the level of ROS, MDA, iron, Fe2+, and Transferrin, and lessened SOD activity and the protein expression of SLC7A11, GPX4, SLC40A1, MEK1, and ERK1/2. Moreover, ferroptosis inhibitor Fer-1 and MEK1 overexpression both reversed the changes on cell proliferation, apoptosis, and ferroptosis induced by β-eudesmol. β-eudesmol inhibited cell proliferation and promoted cell apoptosis and ferroptosis via regulating MAPK pathway in BC.

Genomic signatures of selection, local adaptation and production type characterisation of East Adriatic sheep breeds

BACKGROUND

The importance of sheep breeding in the Mediterranean part of the eastern Adriatic has a long tradition since its arrival during the Neolithic migrations. Sheep production system is extensive and generally carried out in traditional systems without intensive systematic breeding programmes for high uniform trait production (carcass, wool and milk yield). Therefore, eight indigenous Croatian sheep breeds from eastern Adriatic treated here as metapopulation (EAS), are generally considered as multipurpose breeds (milk, meat and wool), not specialised for a particular type of production, but known for their robustness and resistance to certain environmental conditions. Our objective was to identify genomic regions and genes that exhibit patterns of positive selection signatures, decipher their biological and productive functionality, and provide a "genomic" characterization of EAS adaptation and determine its production type.

RESULTS

We identified positive selection signatures in EAS using several methods based on reduced local variation, linkage disequilibrium and site frequency spectrum (eROHi, iHS, nSL and CLR). Our analyses identified numerous genomic regions and genes (e.g., desmosomal cadherin and desmoglein gene families) associated with environmental adaptation and economically important traits. Most candidate genes were related to meat/production and health/immune response traits, while some of the candidate genes discovered were important for domestication and evolutionary processes (e.g., HOXa gene family and FSIP2). These results were also confirmed by GO and QTL enrichment analysis.

CONCLUSIONS

Our results contribute to a better understanding of the unique adaptive genetic architecture of EAS and define its productive type, ultimately providing a new opportunity for future breeding programmes. At the same time, the numerous genes identified will improve our understanding of ruminant (sheep) robustness and resistance in the harsh and specific Mediterranean environment.

Integrative analysis identifies two molecular and clinical subsets in Luminal B breast cancer

Comprehensive multiplatform analysis of Luminal B breast cancer (LBBC) specimens identifies two molecularly distinct, clinically relevant subtypes: Cluster A associated with cell cycle and metabolic signaling and Cluster B with predominant epithelial mesenchymal transition (EMT) and immune response pathways. Whole-exome sequencing identified significantly mutated genes including TP53, PIK3CA, ERBB2, and GATA3 with recurrent somatic mutations. Alterations in DNA methylation or transcriptomic regulation in genes (FN1, ESR1, CCND1, and YAP1) result in tumor microenvironment reprogramming. Integrated analysis revealed enriched biological pathways and unexplored druggable targets (cancer-testis antigens, metabolic enzymes, kinases, and transcription regulators). A systematic comparison between mRNA and protein displayed emerging expression patterns of key therapeutic targets (CD274, YAP1, AKT1, and CDH1). A potential ceRNA network was developed with a significantly different prognosis between the two subtypes. This integrated analysis reveals a complex molecular landscape of LBBC and provides the utility of targets and signaling pathways for precision medicine.

Bioactive Vitamin D Attenuates MED28-Mediated Cell Growth and Epithelial–Mesenchymal Transition in Human Colorectal Cancer Cells

Inadequate vitamin D status may increase the risk of developing multiple types of cancer. Epidemiological studies suggest an inverse association between 25-hydroxyvitamin D₃ (25(OH)D₃) and malignancy, including colorectal cancer. Previous studies have suggested that MED28, a Mediator subunit involved in transcriptional regulation, is associated with the growth of colorectal cancer cells; however, its role in the progression of metastasis such as epithelial–mesenchymal transition (EMT) and cell migration of colorectal cancer is unclear at present. The aim of this study was to investigate a potentially suppressive effect of calcitriol, 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), a bioactive form of vitamin D, and the role of MED28 in the progression of EMT in human colorectal cancer cells. Suppression of MED28 increased the expression of E-cadherin and reduced the expression of several mesenchymal and migration biomarkers and Wnt/β-catenin signaling molecules, whereas overexpression of MED28 enhanced the EMT features. Calcitriol suppressed the expression of MED28, and the effect of calcitriol mirrored that of MED28 silencing. Our data indicate that calcitriol attenuated MED28-mediated cell growth and EMT in human colorectal cancer cells, underlining the significance of MED28 in the progression of colorectal cancer and supporting the potential translational application of calcitriol.

Weighted Single-Step Genome-Wide Association Study Uncovers Known and Novel Candidate Genomic Regions for Milk Production Traits and Somatic Cell Score in Valle del Belice Dairy Sheep

Simple Summary

Milk production is the most economically crucial dairy sheep trait and constitutes the major genetic enhancement purpose via selective breeding. Also, mastitis is one of the most frequently encountered diseases, having a significant impact on animal welfare, milk yield, and quality. The aim of this study was to identify genomic region(s) associated with the milk production traits and somatic cell score (SCS) in Valle del Belice sheep using single-step genome-wide association (ssGWA) and genotyping data from medium density SNP panels. We identified several genomic regions (OAR1, OAR2, OAR3, OAR4, OAR6, OAR9, and OAR25) and candidate genes implicated in milk production traits and SCS. Our findings offer new insights into the genetic basis of milk production traits and SCS in dairy sheep.

Abstract

The objective of this study was to uncover genomic regions explaining a substantial proportion of the genetic variance in milk production traits and somatic cell score in a Valle del Belice dairy sheep. Weighted single-step genome-wide association studies (WssGWAS) were conducted for milk yield (MY), fat yield (FY), fat percentage (FAT%), protein yield (PY), protein percentage (PROT%), and somatic cell score (SCS). In addition, our aim was also to identify candidate genes within genomic regions that explained the highest proportions of genetic variance. Overall, the full pedigree consists of 5534 animals, of which 1813 ewes had milk data (15,008 records), and 481 ewes were genotyped with a 50 K single nucleotide polymorphism (SNP) array. The effects of markers and the genomic estimated breeding values (GEBV) of the animals were obtained by five iterations of WssGBLUP. We considered the top 10 genomic regions in terms of their explained genomic variants as candidate window regions for each trait. The results showed that top ranked genomic windows (1 Mb windows) explained 3.49, 4.04, 5.37, 4.09, 3.80, and 5.24% of the genetic variances for MY, FY, FAT%, PY, PROT%, and total SCS, respectively. Among the candidate genes found, some known associations were confirmed, while several novel candidate genes were also revealed, including PPARGC1A, LYPLA1, LEP, and MYH9 for MY; CACNA1C, PTPN1, ROBO2, CHRM3, and ERCC6 for FY and FAT%; PCSK5 and ANGPT1 for PY and PROT%; and IL26, IFNG, PEX26, NEGR1, LAP3, and MED28 for SCS. These findings increase our understanding of the genetic architecture of six examined traits and provide guidance for subsequent genetic improvement through genome selection.

Role of the Mediator Complex and MicroRNAs in Breast Cancer Etiology

Transcriptional coactivators play a key role in RNA polymerase II transcription and gene regulation. One of the most important transcriptional coactivators is the Mediator (MED) complex, which is an evolutionary conserved large multiprotein complex. MED transduces the signal between DNA-bound transcriptional activators (gene-specific transcription factors) to the RNA polymerase II transcription machinery to activate transcription. It is known that MED plays an essential role in ER-mediated gene expression mainly through the MED1 subunit, since estrogen receptor (ER) can interact with MED1 by specific protein–protein interactions; therefore, MED1 plays a fundamental role in ER-positive breast cancer (BC) etiology. Additionally, other MED subunits also play a role in BC etiology. On the other hand, microRNAs (miRNAs) are a family of small non-coding RNAs, which can regulate gene expression at the post-transcriptional level by binding in a sequence-specific fashion at the 3′ UTR of the messenger RNA. The miRNAs are also important factors that influence oncogenic signaling in BC by acting as both tumor suppressors and oncogenes. Moreover, miRNAs are involved in endocrine therapy resistance of BC, specifically to tamoxifen, a drug that is used to target ER signaling. In metazoans, very little is known about the transcriptional regulation of miRNA by the MED complex and less about the transcriptional regulation of miRNAs involved in BC initiation and progression. Recently, it has been shown that MED1 is able to regulate the transcription of the ER-dependent miR-191/425 cluster promoting BC cell proliferation and migration. In this review, we will discuss the role of MED1 transcriptional coactivator in the etiology of BC and in endocrine therapy-resistance of BC and also the contribution of other MED subunits to BC development, progression and metastasis. Lastly, we identified miRNAs that potentially can regulate the expression of MED subunits.

Genome-wide association study on milk production and somatic cell score for Thai dairy cattle using weighted single-step approach with random regression test-day model

Genome-wide association studies are a powerful tool to identify genomic regions and variants associated with phenotypes. However, only limited mutual confirmation from different studies is available. The objectives of this study were to identify genomic regions as well as genes and pathways associated with the first-lactation milk, fat, protein, and total solid yields; fat, protein, and total solid percentage; and somatic cell score (SCS) in a Thai dairy cattle population. Effects of SNPs were estimated by a weighted single-step GWAS, which back-solved the genomic breeding values predicted using single-step genomic BLUP (ssGBLUP) fitting a single-trait random regression test-day model. Genomic regions that explained at least 0.5% of the total genetic variance were selected for further analyses of candidate genes. Despite the small number of genotyped animals, genomic predictions led to an improvement in the accuracy over the traditional BLUP. Genomic predictions using weighted ssGBLUP were slightly better than the ssGBLUP. The genomic regions associated with milk production traits contained 210 candidate genes on 19 chromosomes [Bos taurus autosome (BTA) 1 to 7, 9, 11 to 16, 20 to 21, 26 to 27 and 29], whereas 21 candidate genes on 3 chromosomes (BTA 11, 16, and 21) were associated with SCS. Many genomic regions explained a small fraction of the genetic variance, indicating polygenic inheritance of the studied traits. Several candidate genes coincided with previous reports for milk production traits in Holstein cattle, especially a large region of genes on BTA14. We identified 141 and 5 novel genes related to milk production and SCS, respectively. These novel genes were also found to be functionally related to heat tolerance (e.g., SLC45A2, IRAG1, and LOC101902172), longevity (e.g., SYT10 and LOC101903327), and fertility (e.g., PAG1). These findings may be attributed to indirect selection in our population. Identified biological networks including intracellular cell transportation and protein catabolism implicate milk production, whereas the immunological pathways such as lymphocyte activation are closely related to SCS. Further studies are required to validate our findings before exploiting them in genomic selection.

Regulatory role of transcription factor HBP1 in anticancer efficacy of EGFR inhibitor erlotinib in HNSCC

BACKGROUND

Epidermal growth factor receptor (EGFR) is often hyperactivated in head and neck squamous cell carcinoma (HNSCC); however, its downstream mediators are not fully identified. Here, we investigate the role of transcription factor HBP1 in the anticancer efficacy of EGFR inhibitor erlotinib in HNSCC.

METHODS

The effect of erlotinib and HBP1 on cell proliferation and invasion was examined by flow cytometric analysis and a Matrigel invasion assay, respectively. Oral tumor specimens were used to evaluate the association between the expression level of EGFR and HBP1, and metastatic potential.

RESULTS

Erlotinib caused cell growth arrest in the G1 phase and sluggish invasion with a concomitant increase in HBP1 and p27 expression. The erlotinib effect was attenuated upon HBP1 knockdown. Analysis of oral tumor specimens revealed that the low HBP1/high EGFR status can predict metastatic potential.

CONCLUSIONS

Our data support HBP1 as a crucial mediator of EGFR-targeting inhibitors in HNSCC.

MED28 Over-Expression Shortens the Cell Cycle and Induces Genomic Instability

The mammalian mediator complex subunit 28 (MED28) is overexpressed in a variety of cancers and it regulates cell migration/invasion and epithelial-mesenchymal transition. However, transcription factors that increase MED28 expression have not yet been identified. In this study, we performed a luciferase reporter assay to identify and characterize the prospective transcription factors, namely E2F transcription factor 1, nuclear respiratory factor 1, E-26 transforming sequence 1, and CCAAT/enhancer-binding protein β, which increased MED28 expression. In addition, the release from the arrest at the G1−S or G2−M phase transition after cell cycle synchronization using thymidine or nocodazole, respectively, showed enhanced MED28 expression at the G1−S transition and mitosis. Furthermore, the overexpression of MED28 significantly decreased the duration of interphase and mitosis. Conversely, a knockdown of MED28 using si-RNA increased the duration of interphase and mitosis. Of note, the overexpression of MED28 significantly increased micronucleus and nuclear budding in HeLa cells. In addition, flow cytometry and fluorescence microscopy analyses showed that the overexpression of MED28 significantly increased aneuploid cells. Taken together, these results suggest that MED28 expression is increased by oncogenic transcription factors and its overexpression disturbs the cell cycle, which results in genomic instability and aneuploidy.

Matrix metalloproteinase-13 is a target gene of high-mobility group box-containing protein 1 in modulating oral cancer cell invasion

Transcription factor high-mobility group box-containing protein 1 (HBP1) may function as a tumor suppressor in various types of cancer. In a previous study, we demonstrated that HBP1 suppressed cell invasion in oral cancer. To further understand the underlying mechanism, the current study is aimed at investigating how HBP1 exerts its antimetastatic potential in oral cancer. In a cell model, ectopic expression of HBP1 potently suppressed epithelial-mesenchymal transition, cellular migration, and invasion; conversely, HBP1 knockdown promoted these malignant phenotypes. The matrix metalloproteinase (MMP) family is highly implicated in tumor metastasis. Therefore, we examined the effect of HBP1 on the activation of the MMP members, MMP-2, -9, and -13 that are highly associated with the aggressiveness of oral cancer. Ectopic expression of HBP1 resulted in a mild reduction in the expression and activity of MMP-2 and -9, yet it had a potent inhibitory effect on MMP-13. In contrast, HBP1 knockdown strongly enhanced the activation of MMP-13. Further, we demonstrated that MMP-13 is a target of HBP1 transcription repression as evidenced by the identification of an HBP1 binding site in the cis proximal region of the MMP-13 promoter. More important, MMP-13 knockdown significantly alleviated HBP1 small interfering RNA-mediated promotion in cell invasion. Analysis of oral tumor specimens revealed that the low HBP1 (<0.3-fold)/high MMP-13 (>3-fold) status was associated with metastatic potential. All told, our study provides evidence supporting the idea that the HBP1-MMP-13 axis is a key regulator of the aggressiveness in oral cancer.

MicroRNA-18a inhibits cell growth and induces apoptosis in osteosarcoma by targeting MED27

Osteosarcoma (OS) is a common malignant primary bone tumor and patients with OS are known to have a poor response to chemotherapy. MicroRNAs (miRNAs or miRs) are small non-coding RNA molecules (approximately 22 nucleotides in length) and they have recently become a topic for research as regards their role in cancer therapeutics. Previous studies have reported miR‑18a expression in patients with OS is significantly decreased compared with that in normal adjacent tissue. miR‑18a belongs to the miR‑17‑92 cluster encoded by the host gene MIR17HG. However, the detailed role of miR‑18a in OS remains to be determined. In this study, we demonstrated that miR‑18a mimics inhibited MG63 and Saos‑2 cell viability and migration. In addition, flow cytometry assay revealed that miR‑18a induced OS cell apoptosis. Western blot analysis indicated that the expression levels of Bcl‑2 and p‑Akt were downregulated, while the levels of cleaved caspase‑3 and Bax proteins were upregulated by miR‑18a. Moreover, we demonstrated that mediator complex subunit 27 (MED27) was the target of miR‑18a through dual luciferase assay. Finally, data from in vivo experiments indicated that tumor growth in mice was significantly suppressed by miR‑18a mimics, accompanied by a decrease in the percentage of Ki67-positive cells, and by the downregulation in MED27 and p‑Akt protein expression levels. The findings of the present study may aid in the clarification of the function of miR‑18a, particularly as regards its role in the regulation of OS cell apoptosis, and indicate that MED27 may be a potential novel therapeutic target in the treatment of OS.

MED28 increases the colony-forming ability of breast cancer cells by stabilizing the ZNF224 protein upon DNA damage

The regulation of gene expression by transcription factors serves a critical function in cell proliferation. Zinc-finger protein 224 (ZNF224), a Krüppel-associated-box-containing zinc finger protein, is known to serve a crucial function in integrating the transcriptional co-factors that activate transcriptional regulation pathways in the cell. A previous study demonstrated that ZNF224 enhances cell proliferation by downregulating the expression of p21 and p53. The present study identified mediator complex subunit 28 (MED28) as a potential binding partner for ZNF224; this was confirmed by co-immunoprecipitation and a surface plasmon resonance assay. Additionally, the KRAB domain at the N-terminal of ZNF224 interacts with the MED domain of MED28. Bimolecular fluorescence complementation analysis revealed that ZNF224 associates with MED28 in the nucleus. In addition, ZNF224 was rapidly degraded upon treatment with the DNA-damaging agent camptothecin (CPT). Transient overexpression of MED28 inhibited the CPT-mediated degradation of ZNF224, resulting in increased colony formation by MCF-7 cells. The molecular mechanisms that underlie the biological outcomes of MED28 expression have not yet been fully elucidated. The present study provides molecular evidence for the function of ZNF224 and MED28 in the DNA-damage response.

Transcription factor HBP1 is a direct anti-cancer target of transcription factor FOXO1 in invasive oral cancer

Either FOXO1 or HBP1 transcription factor is a downstream effector of the PI3K/Akt pathway and associated with tumorigenesis. However, the relationship between FOXO1 and HBP1 in oral cancer remains unclear. Analysis of 30 oral tumor specimens revealed that mean mRNA levels of both FOXO1 and HBP1 in non-invasive and invasive oral tumors were found to be significantly lower than that of the control tissues, and the status of low FOXO1 and HBP1 (< 0.3 fold of the control) was associated with invasiveness of oral tumors. To investigate if HBP1 is a direct transcription target of FOXO1, we searched potential FOXO1 binding sites in the HBP1 promoter using the MAPPER Search Engine, and two putative FOXO1 binding sites located in the HBP1 promoter –132 to –125 bp and –343 to –336 bp were predicted. These binding sites were then confirmed by both reporter gene assays and the in cellulo ChIP assay. In addition, Akt activity manipulated by PI3K inhibitor LY294002 or Akt mutants was shown to negatively affect FOXO1-mediated HBP1 promoter activation and gene expression. Last, the biological significance of the FOXO1-HBP1 axis in oral cancer malignancy was evaluated in cell growth, colony formation, and invasiveness. The results indicated that HBP1 knockdown potently promoted malignant phenotypes of oral cancer and the suppressive effect of FOXO1 on cell growth, colony formation, and invasion was alleviated upon HBP1 knockdown in invasive oral cancer cells. Taken together, our data provide evidence for HBP1 as a direct downstream target of FOXO1 in oral cancer malignancy.

The nematode homologue of Mediator complex subunit 28, F28F8.5, is a critical regulator of C. elegans development

The evolutionarily conserved Mediator complex is a critical player in regulating transcription. Comprised of approximately two dozen proteins, the Mediator integrates diverse regulatory signals through direct protein-protein interactions that, in turn, modulate the influence of Mediator on RNA Polymerase II activity. One Mediator subunit, MED28, is known to interact with cytoplasmic structural proteins, providing a potential direct link between cytoplasmic dynamics and the control of gene transcription. Although identified in many animals and plants, MED28 is not present in yeast; no bona fide MED28 has been described previously in Caenorhabditis elegans. Here, we identify bioinformatically F28F8.5, an uncharacterized predicted protein, as the nematode homologue of MED28. As in other Metazoa, F28F8.5 has dual nuclear and cytoplasmic localization and plays critical roles in the regulation of development. F28F8.5 is a vital gene and its null mutants have severely malformed gonads and do not reproduce. F28F8.5 interacts on the protein level with the Mediator subunits MDT-6 and MDT-30. Our results indicate that F28F8.5 is an orthologue of MED28 and suggest that the potential to link cytoplasmic and nuclear events is conserved between MED28 vertebrate and nematode orthologues.

Quercetin suppresses cellular migration and invasion in human head and neck squamous cell carcinoma (HNSCC)

Head and neck squamous cell carcinoma (HNSCC) with aberrant epidermal growth factor receptor (EGFR) signaling is often associated with a poor prognosis and a low survival rate. Hence, efficient inhibition of the EGFR signaling-mediated malignancy would improve survival rate. In a previous study, we demonstrated that quercetin appears to be a potent anti-tumorigenic agent through its inhibition of the EGFR/Akt pathway in oral cancer, but its anti-metastatic potential in HNSCC remains unclear [1]. Here, we have hypothesized that quercetin might be effective in metastatic inhibition in EGFR-overexpressing HNSCC cells. Quercetin treatment with 10 μM (half concentration of IC50) suppressed cell migration and invasion in EGFR-overexpressing HSC-3 and FaDu HNSCC cells. Quercetin also inhibited the colony growth of HSC-3 cells embedded in a Matrigel matrix. Among matrix metalloproteinases (MMPs), the secreted gelatinases MMP-2 and MMP-9 are responsible for the degradation of gelatin in the extracellular matrix and type IV collagen in the basement membrane; and this degradation event is crucial for the migration from the origin and the invasion into the bone in HNSCC. Quercetin (10 μM) treatment also suppressed the expression and proteolytic activity of MMP-2 and MMP-9. Taken together, our data indicate that quercetin is an effective anti-cancer agent against MMP-2- and MMP-9-mediated metastasis in EGFR-overexpressing HNSCC.

MED27 promotes melanoma growth by targeting AKT/MAPK and NF-κB/iNOS signaling pathways

The inhibitors of BRAF and MEK targeting MAPK signaling pathway provide a comparatively effective therapeutic strategy for melanoma caused by BRAF mutation. However, melanoma, especially metastatic melanoma, has become one of the most threatening malignancies. Thus, the identification of exact molecular mechanisms and the key components involved in such mechanisms is urgently needed in order to provide new therapeutic options for patients with melanoma. Here, we identified MED27 as a potential melanoma target and explored its role and the associated molecular mechanism involved in melanoma progression. MED27 was found to be highly expressed in melanoma cells and tumor tissues. Its silencing led to melanoma cell proliferation inhibition, cell cycle arrest and apoptosis induction accompanied by the inactivation of PI3K/AKT and MAPK/ERK signaling and the activation of Bax/Cyto-C/Caspase-dependent apoptotic pathway. In addition, silencing of MED27 led to the decrease of iNOS expression through inhibiting the activation of a serial of upstream key proteins of NF-κB signaling pathway and the translocation of p50/p65 from cytoplasm to nucleus. MED27 was also found to be able to interact with NF-κB and p300 and to be acetylated by p300. Furthermore, the results in a xenograft tumor model indicated that melanoma progression was effectively suppressed by MED27 knockdown accompanied by the down-regulation of p-AKT, p-ERK, p-MEK1/2, MMP-9, Bcl-2 and iNOS expressions in the tumor tissues. Taken together, our study not only demonstrated the new function of MED27 as an oncogenic protein and the associated molecular mechanisms involved in melanoma progression, but also provided a possibility for the development of MED27 as a new anticancer target in melanoma therapy.

Elevated Serum MicroRNA Let-7c in Moyamoya Disease

BACKGROUND

Few studies have examined the relationship between mircroRNAs and moyamoya disease (MMD). We performed a study of the significance of let-7c expression in the serum of MMD patients.

METHODS

The experimental group includes 49 MMD patients, and the control group consists of 30 normal people, 20 cerebral hemorrhage patients, 20 massive cerebral infarction patients, 20 nonmassive cerebral infarction patients, and 20 neurological autoimmune disease patients. Let-7 family levels were determined by polymerase chain reaction. A dual luciferase assay was used to test whether let-7c recognized the 3'UTR of RNF213.

RESULTS

The expression level of let-7c in MMD patients is higher than that observed in the control groups (P < .001). The luciferase assay results indicated that hsa-let-7c could diminish luciferase activity from a reporter vector containing the 3'-UTR of RNF213 (P < .05). The suppression of luciferase activity is not found in mutRNF213 (P > .05).

CONCLUSIONS

Increased expression of let-7c in MMD patients may contribute to MMD pathogenesis by targeting RNF213. Thus, let-7c may be a potential biomarker for the diagnosis of MMD.

Involvement of Mediator complex in malignancy

Mediator complex (MED) is an evolutionarily conserved multiprotein, fundamental for growth and survival of all cells. In eukaryotes, the mRNA transcription is dependent on RNA polymerase II that is associated to various molecules like general transcription factors, MED subunits and chromatin regulators. To date, transcriptional machinery dysfunction has been shown to elicit broad effects on cell proliferation, development, differentiation, and pathologic disease induction, including cancer. Indeed, in malignant cells, the improper activation of specific genes is usually ascribed to aberrant transcription machinery. Here, we focus our attention on the correlation of MED subunits with carcinogenesis. To date, many subunits are mutated or display altered expression in human cancers. Particularly, the role of MED1, MED28, MED12, CDK8 and Cyclin C in cancer is well documented, although several studies have recently reported a possible association of other subunits with malignancy. Definitely, a major comprehension of the involvement of the whole complex in cancer may lead to the identification of MED subunits as novel diagnostic/prognostic tumour markers to be used in combination with imaging technique in clinical oncology, and to develop novel anti-cancer targets for molecular-targeted therapy.

Identification of breast cancer patients based on human signaling network motifs

Identifying breast cancer patients is crucial to the clinical diagnosis and therapy for this disease. Conventional gene-based methods for breast cancer diagnosis ignore gene-gene interactions and thus may lead to loss of power. In this study, we proposed a novel method to select classification features, called “Selection of Significant Expression-Correlation Differential Motifs” (SSECDM). This method applied a network motif-based approach, combining a human signaling network and high-throughput gene expression data to distinguish breast cancer samples from normal samples. Our method has higher classification performance and better classification accuracy stability than the mutual information (MI) method or the individual gene sets method. It may become a useful tool for identifying and treating patients with breast cancer and other cancers, thus contributing to clinical diagnosis and therapy for these diseases.