The metabolic checkpoint kinase mechanistic/mammalian target of rapamycin (mTOR) regulates natural killer (NK) cell development and function, but the exact underlying mechanisms remain unclear. Here, we show, via conditional deletion of Raptor (mTORC1) or Rictor (mTORC2), that mTORC1 and mTORC2 promote NK cell maturation in a cooperative and non-redundant manner, mainly by controlling the expression of Tbx21 and Eomes. Intriguingly, mTORC1 and mTORC2 regulate cytolytic function in an opposing way, exhibiting promoting and inhibitory effects on the anti-tumor ability and metabolism, respectively. mTORC1 sustains mTORC2 activity by maintaining CD122-mediated IL-15 signaling, whereas mTORC2 represses mTORC1-modulated NK cell effector functions by restraining STAT5-mediated SLC7A5 expression. These positive and negative crosstalks between mTORC1 and mTORC2 signaling thus variegate the magnitudes and kinetics of NK cell activation, and help define a paradigm for the modulation of NK maturation and effector functions.
Recent data have shown that the expression of lysosome-associated membrane protein type 2 A (LAMP2A), the key protein in the chaperone-mediated autophagy (CMA) pathway, is elevated in breast tumor tissues. However, the exact effects and mechanisms of CMA during breast cancer metastasis remain largely unknown. In this study, we found that the LAMP2A protein level was significantly elevated in human breast cancer tissues, particularly in metastatic carcinoma. The increased LAMP2A level was also positively correlated with the histologic grade of ductal breast cancer. High LAMP2A levels also predicted shorter overall survival of breast cancer patients. Downregulation of CMA activity by LAMP2A knockdown significantly inhibited the growth and metastasis of both MDA-MB-231 and MDA-MB-468 breast cancer cells in vivo and in vitro, while upregulation of CMA activity by LAMP2A overexpression had the opposite effect. Mechanistically, we found that elevated CMA activity mediated increased growth and metastasis of human breast cancer cells by downregulating the activity of autophagy-related gene 5 (ATG5)-dependent macroautophagy. Collectively, these results indicate that the anti-macroautophagic property is a key feature of CMA-mediated tumorigenesis and metastasis and may, in some contexts, serve as an attractive target for breast cancer therapies.
Long noncoding RNAs (lncRNAs) were reported to participate in the progression of gastric cancer (GC). However, little is known about the biological functions of TTN antisense RNA 1 (TTN-AS1) in GC. Using qRT-PCR examination, we found that TTN-AS1 was expressed at a higher level in GC tissues and cell lines compared to the normal controls. Kaplan-Meier analysis of GC patients revealed the negative correlation between TTN-AS1 expression and the overall survival. To detect the biological function of TTN-AS1 in GC, we silenced TTN-AS1 to perform loss-of-function assays. The experimental results revealed that knockdown of TTN-AS1 obviously inhibited GC cell proliferation, induced cell apoptosis and impaired cell migration and invasion. In mechanism, TTN-AS1 was located in the cytoplasm of GC cells, indicating the post-transcriptional regulation of TTN-AS1 on gene expression. Bioinformatics analysis revealed the potential binding relation between TTN-AS1 and miR-376b-3p as well as between miR-376b-3p and KLF12. Mechanism experiments such as luciferase reporter assay and RNA pull-down assay demonstrated the interaction between TTN-AS1 and miR-376b-3p as well as between miR-376b-3p and KLF12 in GC cells. At last, rescue assays certified that miR-376b-3p and KLF12 involved in TTN-AS1-mediated GC progression. Similarly, the role of TTN-AS1-miR-376b-3p-KLF12 axis in GC progression was analyzed and validated. Taken together, we concluded that TTN-AS1 might function as a novel potential therapeutic target in the treatment of gastric cancer.
Maternal inflammation contributes to the increased incidence of adult cardiovascular disease. The current study investigated the susceptibility of cardiac damage responding to isoproterenol (ISO) in adult offspring that underwent maternal inflammation (modeled by pregnant Sprague-Dawley rats with lipopolysaccharides (LPS) challenge). We found that 2 weeks of ISO treatment in adult offspring of LPS-treated mothers led to augmented heart damage, characterized by left-ventricular systolic dysfunction, cardiac hypertrophy and myocardial fibrosis. Mechanistically, prenatal exposure to LPS led to up-regulated expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, antioxidant enzymes, and p38 MAPK activity in left ventricular of adult offspring at resting state. ISO treatment exaggerated ROS generation, p38 MAPK activation but down-regulated reactive oxygen species (ROS) elimination capacity in the left ventricular of offspring from LPS-treated mothers, while antioxidant N-acetyl-L-cysteine (NAC) reversed these changes together with improved cardiac functions. The p38 inhibitor SB202190 alleviated the heart damage only via inhibiting the expression of NADPH oxidases. Collectively, our data demonstrated that prenatal inflammation programs pre-existed ROS activation in the heart tissue, which switches on the early process of oxidative damages on heart rapidly through a ROS-p38 MAPK-NADPH oxidase-ROS positive feedback loop in response to a myocardial hypertrophic challenge in adulthood.
This study aims to investigate the role of the long non-coding RNA (lncRNA) HOX transcript antisense RNA (HOTAIR) in the regulation of anoikis resistance of ovarian cancer c ells, a prerequisite for metastasis and chemoresistance in ovarian cancer cells. Ova rian cancer SKOV3 cells were cultured in an ultra-low attachment system to establish an anoikis model. The relationship between cellular anoikis capability and HOTAIR expression level was studied by flow cytometry and RT-PCR. The ability of spheroid formation, migration, and invasion of the suspended cells was assessed following the knockdown of HOTAIR expression. The expression of EZH2, H3K27me3, representative targets of EZH2, and anoikis-related biomarkers was also detected. An increase in the duration of suspension culture time rendered the SKOV3 cells anoikis-resistant with a significantly lower apoptotic rate compared to the adherent cells. HOTAIR expression in the suspension cells increased significantly, while that in the adherent cells did not. Following small interfering RNA (siRNA)-mediated knockdown of HOTAIR expression, the abilities of anoikis resistance, migration, and invasion decreased in the suspension cells. Knockdown of HOTAIR levels also reduced the spheroid forming ability of the tumor c ells in continuous suspension cultures. Moreover, EZH2 expression correlated with HOTAIR expression, thus regulating the expression of miR-193a and DOK2 via introducing H3K27me3. Western blot analysis of anoikis-related markers showed that N-cadherin, ZEB1, and TWIST1 were downregulated following inhibition of HOTAIR, while E-cadherin and ErbB3 were upregulated. In conclusion, HOTAIR enhances the anoikis resistance and spheroid forming ability of ovarian cancer cells by recruiting EZH2 and influencing H3K27 methylation that may contribute to migration, invasion, and chemoresistance of ovarian cancer cells.
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