Nrf2 promotes breast cancer cell migration via up-regulation of G6PD/HIF-1α/Notch1 axis.

Abnormal metabolism of tumour cells is closely related to the occurrence and development of breast cancer, during which the expression of NF-E2-related factor 2 (Nrf2) is of great significance. Metastatic breast cancer is one of the most common causes of cancer death worldwide; however, the molecular mechanism underlying breast cancer metastasis remains unknown. In this study, we found that the overexpression of Nrf2 promoted proliferation and migration of breast cancers cells. Inhibition of Nrf2 and overexpression of Kelch-like ECH-associated protein 1 (Keap1) reduced the expression of glucose-6-phosphate dehydrogenase (G6PD) and transketolase of pentose phosphate pathway, and overexpression of Nrf2 and knockdown of Keap1 had opposite effects. Our results further showed that the overexpression of Nrf2 promoted the expression of G6PD and Hypoxia-inducing factor 1α (HIF-1α) in MCF-7 and MDA-MB-231 cells. Overexpression of Nrf2 up-regulated the expression of Notch1 via G6PD/HIF-1α pathway. Notch signalling pathway affected the proliferation of breast cancer by affecting its downstream gene HES-1, and regulated the migration of breast cancer cells by affecting the expression of EMT pathway. The results suggest that Nrf2 is a potential molecular target for the treatment of breast cancer and targeting Notch1 signalling pathway may provide a promising strategy for the treatment of Nrf2-driven breast cancer metastasis.

NRF2 facilitates breast cancer cell growth via HIF1ɑ-mediated metabolic reprogramming.

High aerobic glycolysis not only provides energy to breast cancer cells, but also supports their anabolic growth. The redox sensitive transcription factor NRF2 is over-expressed in multiple cancers, including breast cancer. It is unclear whether NRF2 could promote breast cancer cell growth through enhancing glycolysis. In this study, we found that NRF2 and HIF1α mRNA and protein levels were significantly increased in MCF-7 and MDA-MB-231 breast cancer cells as compared to MCF-10A benign breast epithelial cells. Down-regulation of NRF2 decreased MCF7 and MBA-DA-231 breast cell proliferation, while it reversed by hypoxia inducible factor 1α (HIF1α). Knockdown of NRF2 inhibited glycolysis by decreasing the expression of genes participated in glucose metabolism, including HK2, PFKFB3, PKM2 and LDHA. Our results further indicated that the AKT activation and AMPK inhibition were required for NRF2-mediated up-regulation of glycolytic enzymes. Consistent with these results, a positive correlation existed between NRF2 or HIF1α and several key glycolytic genes in human breast cancer cell samples and breast cancer patients with high NRF2 or HIF1α expression had poorer overall survival. In conclusion, our study demonstrates that NRF2 promotes breast cancer progression by enhancing glycolysis through coactivation of HIF1α, implicating that NRF2 is a potential molecular target for breast cancer treatment.

Loss of TET1 facilitates DLD1 colon cancer cell migration via H3K27me3-mediated down-regulation of E-cadherin.

Epigenetic modifications such as histone modifications and cytosine hydroxymethylation are linked to tumorigenesis. Loss of 5-hydroxymethylcytosine (5 hmC) by ten-eleven translocation 1 (TET1) down-regulation facilitates tumor initiation and development. However, the mechanisms by which loss of TET1 knockdown promotes malignancy development remains unclear. Here, we report that TET1 knockdown induced epithelial-mesenchymal transition (EMT) and increased cancer cell growth, migration, and invasion in DLD1 cells. Loss of TET1 increased EZH2 expression and reduced UTX-1 expression, thus increasing histone H3K27 tri-methylation causing repression of the target gene E-cadherin. Ectopic expression of the H3K27 demethylase UTX-1 or EZH2 depletion both impeded EZH2 binding caused a loss of H3K27 methylation at epithelial gene E-cadherin promoter, thereby suppressing EMT and tumor invasion in shTET1 cells. Conversely, UTX-1 depletion and ectopic expression of EZH2 enhanced EMT and tumor metastasis in DLD1 cells. These findings provide insight into the regulation of TET1 and E-cadherin and identify EZH2 as a critical mediator of E-cadherin repression and tumor progression.

PKM2-mediated inhibition of autophagy facilitates Tat's inducing HIV-1 transactivation.

Considerable evidence has shown that autophagy has an important role in HIV-1 infection. However, it is still unknown whether metabolism-regulated autophagy pathway is involved in Tat-mediated HIV-1 transactivation. This study demonstrated that treatment of Tat in TZM-bl cells significantly down-regulated protein levels of Beclin-1, Atg-5, Atg-7, and LC3B-II and up-regulated of p62 levels. Blockage of autophagy enhanced Tat-induced HIV-1 transactivation in TZM-bl cells. Moreover, we found that Tat activated the Akt/mTOR and inhibited AMPK signaling pathway that was related to its up-regulation of PKM2 expression. In addition, we showed that PI3K/AKT activation and AMPK inhibtion was required for the PKM2-mediated inhibition of autophagy in Tat-treated TZM-bl cells. In conclusion, our data reveals that PKM2-mediated autophagy inhibition is required for Tat-mediated HIV-1 transactivation. Metabolism-related autophagic pathway may act as a promising diagnostic and therapeutic tool for HIV-1 infection in the future.

UTX-1 regulates Tat-induced HIV-1 transactivation via changing the methylated status of histone H3.

Epigenetic modifications are thought to be important for gene expression changes during HIV-1 transcription and replication. The removal of histone H3 lysine27 (H3K27) trimethylation mark by UTX-1 is important for the robust induction of many specific genes during Tat-mediated HIV-1 transactvation. We found that UTX-1 enzymatic activity is needed for Tat to remove a repressive mark H3K27me3 in the HIV-1 long terminal repeat (LTR). UTX-1 converted the chromatin structure to a more transcriptionally active state by up-regulation of H3K4 methylation and down-regulation of H3K27 methylation on the specific regions of HIV-1 LTR. The increase in H3K27me3 and the decrease in H3K4me3 induced by UTX-1 knockdown was detected on the HIV-1 LTR, but not by control siRNA. Additionally, UTX-1 promotes HIV-1 gene expression by enhancing both the NF-κB p65's nuclear translocation and its p65 binding to HIV-1 LTR. And we further demonstrated that H3K27 demethylase activity was required for increased HIV-1 transactivation induced by UTX-1. Together, our data reveal key roles for UTX-1 in a timely transition from poised to active chromatin in HIV-1 LTR during HIV-1 transcription and a fundamental mechanism by which a H3K27 demethylase triggers tissue-specific chromatin changes. Our findings provide a mechanistic link between UTX-1 and enhanced HIV-1 replication, and suggest that targeting at epigenetic mechanism may have a therapeutic benefit for HIV-1 patients.

[Applications of nuclear magnetic resonance in the study of soil-plant-atmosphere continuum].

Status and transport of water in plant body are the main contents of study of soil-plant-atmosphere continuum (SPAC), as well as the base for use and regulation of agricultural water. The process of water transport in plant can be deeply influenced by the environments. Thus, plant needs to adjust its water status to accommodate the environmental change to sustain its own growth and development. Traditional methods for plant water monitoring, such as evaporation flux, pressure chamber, high pressure flow meter, heat pulse, and so on, usually cause damage or even destruction of plant body and disturb the original water status. Thus, they are not able to truly and precisely detect and reflect the real water status of plant. Nuclear magnetic resonance (NMR) is a non-destructive and non-invasive technique which can be used for the measurement of water molecular displacement, and transportation. This study aimed to provide an overview of the applications of NMR technique in the study of water distribution and transport in plant roots and stems, as well as the water content in plant cells and tissues. In addition, the existing main problems and possible solutions were analyzed for the applications of NMR in SPAC studies. Several important issues were proposed for the acquisition of more precise and reliable detection signals. It was suggested that the NMR technique would probably make important progress in the relevant fields such as plant water physiology, plantenvironment interactions, and water metabolism. In general, the application of NMR in SPAC system study was still in its infancy in China. The deeper application and expansion of NMR in SPAC study would depend on the development of portable and open NMR equipment that could be easily applied for different plants in field.

Tanshinone â ¡A inhibits human esophageal cancer cell growth through miR-122-mediated PKM2 down-regulation.

Pyruvate kinase M2 (PKM2) plays a pivotal role in the growth, survival and metabolic reprogramming of cancer cells. Here, we presented for the first time that tanshinone ⅡA inhibited human esophagus cancer cell growth through miR-122-mediated PKM2 down-regulation pathway. Tanshinone ⅡA inhibited cell proliferation and induced cell cycle arrest in S phase in human Ec109 cells. As expected, tanshinone ⅡA down-regulated PKM2 mRNA and protein expression in Ec109 cells. Given these findings, we further investigated microRNAs regulation of PKM2 and confirmed miR-122 for targeting PKM2. Moreover, we found that tanshinone ⅡA-induced up-regulation of miR-122 expression inhibited PKM2 expression in Ec109 cells. Meanwhile, tanshinone ⅡA inhibited proliferation through miR122-medated PKM2 down-regulation. It was demonstrated that the anticancer activity of tanshinone ⅡA was targeted at metabolic regulation of miR-122/PKM2 in human esophagus cancer cells. Taken together, our results revealed tanshinone ⅡA targeting at PKM2-mediated metabolic reprogramming play an important role in inhibition of esophageal cancer cell growth.

EZH2 phosphorylation regulates Tat-induced HIV-1 transactivation via ROS/Akt signaling pathway.

EZH2 plays a major role in HIV-1 latency, however, the molecular linkage between Tat-induced HIV-1 transactivation and EZH2 activity is not fully understood. It was shown Tat induced HIV-1 transactivation through inhibiting EZH2 activity. Tat decreased the levels of H3K27me3 and EZH2 occupy at the long terminal repeat (LTR) of HIV-1. We further showed for the first time that transfected with Tat construct resulted in an increase in phosphorylated EZH2 (p-EZH2), mediated by active Akt. ROS/Akt-dependent p-EZH2 was correlated with Tat-induced transactivation. Our study reveals that novel mechanisms allow Tat-induced HIV-1 transactivation by ROS/Akt-dependent downregulating the EZH2 epigenetic silencing machinery.

Proteome analysis of chloroplast proteins in stage albinism line of winter wheat (triticum aestivum) FA85.

The "stage albinism line of winter wheat" FA85 was a specific natural mutant strain on leaf color. This physiological mutation was controlled by cytogene. In order to reveal the genetic and biochemical mechanism of albinism, 2-DE was used to investigate the difference of chloroplast protein expression pattern between FA85 and its parent wheat Aibian 1. From the results of 2-DE gels analysis, approximately 683 spots were detected on each gel, and 57 spots were expressed differently at least two-fold. Using MALDI-TOF/TOF MS, 14 of 57 spots were identified, which could be categorized into four classes: carbon metabolism, energy metabolism, defense/stress response and signal transduction. Compared with the parent wheat, the expression of ATPase-gamma and GP1-alpha was up-regulated in FA85, and of other proteins was down-regulated. Together, we concluded that the expression of chloroplast proteins had changed obviously in FA85, which might be related to the leaf color mutant.