Epigenetic marks such as histone modifications play roles in various chromosome dynamics in mitosis and meiosis. Methylation of histones H3 at positions K4 and K79 is involved in the initiation of recombination and the recombination checkpoint, respectively, during meiosis in the budding yeast. Set1 promotes H3K4 methylation while Dot1 promotes H3K79 methylation. In this study, we carried out detailed analyses of meiosis in mutants of the SET1 and DOT1 genes as well as methylation-defective mutants of histone H3. We confirmed the role of Set1-dependent H3K4 methylation in the formation of double-strand breaks (DSBs) in meiosis for the initiation of meiotic recombination, and we showed the involvement of Dot1 (H3K79 methylation) in DSB formation in the absence of Set1-dependent H3K4 methylation. In addition, we showed that the histone H3K4 methylation-defective mutants are defective in SC elongation, although they seem to have moderate reduction of DSBs. This suggests that high levels of DSBs mediated by histone H3K4 methylation promote SC elongation.

BackgroundDespite the remarkable progress to fight against breast cancer, metastasis remains the dominant cause of treatment failure and recurrence. Therefore, control of invasiveness potential of breast cancer cells is crucial. Accumulating evidences suggest Aryl hydrocarbon receptor (Ahr), a helix-loop-helix transcription factor, as a promising target to control migration and invasion in breast cancer cells. Thus, an Ahr-based exploration was performed to identify a new Ahr agonist with inhibitory potentials on cancer cell motility.MethodsFor prediction of potential interactions between Ahr and candidate molecules, bioinformatics analysis was carried out. The interaction of the selected ligand with Ahr and its effects on migration and invasion were examined in vitro using the MDA-MB-231 and T47D cell lines. The silencing RNAs were transfected into cells by electroporation. Expressions of microRNAs (miRNAs) and coding genes were quantified by real-time PCR, and the protein levels were detected by western blot.ResultsThe in silico and in vitro results identified Flavipin as a novel Ahr agonist. It induces formation of Ahr/Ahr nuclear translocator (Arnt) heterodimer to promote the expression of cytochrome P450 family 1 subfamily A member 1 (Cyp1a1). Migration and invasion of MDA-MB-231 and T47D cells were inhibited with Flavipin treatment in an Ahr-dependent fashion. Interestingly, Flavipin suppressed the pro-metastatic factor SRY-related HMG-box4 (Sox4) by inducing miR-212/132 cluster. Moreover, Flavipin inhibited growth and adhesion of both cell lines by suppressing gene expressions of B-cell lymphoma 2 (Bcl2) and integrinα4 (ITGA4).ConclusionTaken together, the results introduce Flavipin as a novel Ahr agonist, and provide first evidences on its inhibitory effects on cancer cell motility, suggesting Flavipin as a candidate to control cell invasiveness in breast cancer patients.

Our findings identify miR-132 as a new molecule implicated in CAC pathogenesis, and reveal that miR-132 mediates the ameliorating effects of TCDD on CAC, suggesting miR-132 as a promising therapeutic candidate to control autoimmune inflammation and tumorigenesis in CAC patients.

Homologous chromosomes pair with each other during meiosis, culminating in the formation of the synaptonemal complex (SC), which is coupled with meiotic recombination. In this study, we showed that a meiosis-specific depletion mutant of a cullin (Cdc53) in the SCF (Skp-Cullin-F-box) ubiquitin ligase, which plays a critical role in cell cycle regulation during mitosis, is deficient in SC formation. However, the mutant is proficient in forming crossovers, indicating the uncoupling of meiotic recombination with SC formation in the mutant. Furthermore, the deletion of the PCH2 gene encoding a meiosis-specific AAA+ ATPase suppresses SC-assembly defects induced by CDC53 depletion. On the other hand, the pch2 cdc53 double mutant is defective in meiotic crossover formation, suggesting the assembly of SC with unrepaired DNA double-strand breaks. A temperature-sensitive mutant of CDC4, which encodes an F-box protein of SCF, shows meiotic defects similar to those of the CDC53-depletion mutant. These results suggest that SCFCdc4, probably SCFCdc4-dependent protein ubiquitylation, regulates and collaborates with Pch2 in SC assembly and meiotic recombination.

Chemo-resistance and metastatic disease development are the most common causes of breast cancer recurrence and death. Thidiazuron (TDZ) is a plant growth regulator, its biological role on human and animals has not been yet clarified. In the present study, we investigated the anticancer activity of this plant phytohormone on the drug resistant-triple negative breast cancer MDA-MB-231 cell line. Treatment of the breast cancer cells with TDZ (1-50 μM) caused more stressful environment and induced a significant increase in percentages of active caspases positive cells. In addition, TDZ treatment (5 and 10 μM) significantly attenuated the migration and the invasion activities of these highly metastatic cancer cells. Mechanistically, TDZ reducesd cancer progression and invasive activity through targeting miR-202-5p, which stimulatesd the expression of the phosphatase and tensin homolog (PTEN), the tumor suppressor that downregulates PI3K/AKT signaling pathway. In the meantime, TDZ treatment statistically upregulatesd the suppressor of breast cancer proliferation, miRNA-132 that is also implicated in dysregulating the TEN-AKT/the nuclear factor NFκB signaling pathway. Interestingly, our molecular docking analysis revealed potential non-covalent interaction between TDZ with AKT, PTEN and PI3K. These findings suggest that TDZ may suppresses breast cancer metastasis through targeting miRNA-132, miR-202-5p/PTEN and PI3K/AKT downstream molecules.

Zearalenone are widely occurring food contaminants that cause hepatotoxicity. This research work aimed to investigate how zerumbone, a plant-derived dietary compound, can fight ZEA-induced hepatotoxicity. ZER is found to increase the cells’ toxin resistance. This study was performed on mice challenged with ZEA. The administration of ZER decreased the level of alkaline phosphatase and alanine aminotransferase (ALT). Simultaneously, ZER attenuated the inflammatory response via significantly reducing the levels of pro-inflammatory factors, including interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) in serum. Pretreatment with ZER reduced the hepatic malondialdehyde (MDA) concentration, as well as the depletion of hepatic superoxide dismutase (SOD), hepatic glutathione (GSH), and hepatic catalase (CAT). Moreover, it significantly ameliorated ZEA-induced liver damage and histological hepatocyte changes. ZER also relieved ZEA-induced apoptosis by regulating the PI3K/AKT pathway and Nrf2 and HO-1 expression. Furthermore, ZER increasingly activated Bcl2 and suppressed apoptosis marker proteins. Our findings suggest that ZER exhibits the ability to prevent ZEA-induced liver injury and present the underlying molecular basis for potential applications of ZER to cure liver injuries.

Doxorubicin increases endothelial permeability, hence increasing cardiomyocytes’ exposure to doxorubicin (DOX) and exposing myocytes to more immediate damage. Reactive oxygen species are major effector molecules of doxorubicin’s activity. Mangiferin (MGN) is a xanthone derivative that consists of C-glucosylxanthone with additional antioxidant properties. This particular study assessed the effects of MGN on DOX-induced cytotoxicity in human umbilical vein endothelial cells’ (HUVECs’) signaling networks. Mechanistically, MGN dramatically elevated Nrf2 expression at both the messenger RNA and protein levels through the upregulation of the PI3K/AKT pathway, leading to an increase in Nrf2-downstream genes. Cell apoptosis was assessed with a caspase-3 activity assay, transferase-mediated dUTP-fluorescein nick end labeling (TUNEL) staining was performed to assess DNA fragmentation, and protein expression was determined by Western blot analysis. DOX markedly increased the generation of reactive oxygen species, PARP, caspase-3, and TUNEL-positive cell numbers, but reduced the expression of Bcl-2 and antioxidants’ intracellular concentrations. These were effectively antagonized with MGN (20 μM), which led to HUVECs being protected against DOX-induced apoptosis, partly through the PI3K/AKT-mediated NRF2/HO-1 signaling pathway, which could theoretically protect the vessels from severe DOX toxicity.

Aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor belonging to the basic helix–loop–helix (bHLH)/per-Arnt-sim (PAS) superfamily, is traditionally known to mediate xenobiotic metabolism. It is activated by structurally diverse agonistic ligands and regulates complicated transcriptional processes through its canonical and non-canonical pathways in normal and malignant cells. Different classes of AhR ligands have been evaluated as anticancer agents in different cancer cells and exhibit efficiency, which has thrust AhR into the limelight as a promising molecular target. There is strong evidence demonstrating the anticancer potential of exogenous AhR agonists including synthetic, pharmaceutical, and natural compounds. In contrast, several reports have indicated inhibition of AhR activity by antagonistic ligands as a potential therapeutic strategy. Interestingly, similar AhR ligands exert variable anticancer or cancer-promoting potential in a cell- and tissue-specific mode of action. Recently, ligand-mediated modulation of AhR signaling pathways and the associated tumor microenvironment is emerging as a potential approach for developing cancer immunotherapeutic drugs. This article reviews advances of AhR in cancer research covering publication from 2012 to early 2023. It summarizes the therapeutic potential of various AhR ligands with an emphasis on exogenous ligands. It also sheds light on recent immunotherapeutic strategies involving AhR.