p52 signaling promotes cellular senescence

Identification of STAT3 as a biomarker for cellular senescence in liver fibrosis: A bioinformatics and experimental validation study

BACKGROUND

Cellular senescence is associated with a dysregulated inflammatory response, which is an important driver of the development of liver fibrosis (LF). This study aimed to investigate the effect of cellular senescence on LF and identify potential key biomarkers through bioinformatics analysis combined with validation experiments in vivo and in vitro.

METHODS

The Gene Expression Omnibus (GEO) database and GeneCards database were used to download the LF dataset and the aging-related gene set, respectively. Functional enrichment analysis of differential genes was then performed using GO and KEGG. Hub genes were further screened using Cytoscape's cytoHubba. Diagnostic values for hub genes were evaluated with a receiver operating characteristic (ROC) curve. Next, CIBERSORTx was used to estimate immune cell types and ratios. Finally, in vivo and in vitro experiments validated the results of the bioinformatics analysis. Moreover, molecular docking was used to simulate drug-gene interactions.

RESULTS

A total of 44 aging-related differentially expressed genes (AgDEGs) were identified, and enrichment analysis showed that these genes were mainly enriched in inflammatory and immune responses. PPI network analysis identified 6 hub AgDEGs (STAT3, TNF, MMP9, CD44, TGFB1, and TIMP1), and ROC analysis showed that they all have good diagnostic value. Immune infiltration suggested that hub AgDEGs were significantly associated with M1 macrophages or other immune cells. Notably, STAT3 was positively correlated with α-SMA, COL1A1, IL-6 and IL-1β, and was mainly expressed in hepatocytes (HCs). Validation experiments showed that STAT3 expression was upregulated and cellular senescence was increased in LF mice. A co-culture system of HCs and hepatic stellate cells (HSCs) further revealed that inhibiting STAT3 reduced HCs senescence and suppressed HSCs activation. In addition, molecular docking revealed that STAT3 was a potential drug therapy target.

CONCLUSIONS

STAT3 may be involved in HCs senescence and promote HSCs activation, which in turn leads to the development of LF. Our findings suggest that STAT3 could be a potential biomarker for LF.

Sustained activation of NF-κB through constitutively active IKKβ leads to senescence bypass in murine dermal fibroblasts

Although the transcription factor nuclear factor κB (NF-κB) plays a central role in the regulation of senescence-associated secretory phenotype (SASP) acquisition, our understanding of the involvement of NF-κB in the induction of cellular senescence is limited. Here, we show that activation of the canonical NF-κB pathway suppresses senescence in murine dermal fibroblasts. IκB kinase β (IKKβ)-depleted dermal fibroblasts showed ineffective NF-κB activation and underwent senescence more rapidly than control cells when cultured under 20% oxygen conditions, as indicated by senescence-associated β-galactosidase (SA-β-gal) staining and p16INK4a mRNA levels. Conversely, the expression of constitutively active IKKβ (IKKβ-CA) was sufficient to drive senescence bypass. Notably, the expression of a degradation-resistant form of inhibitor of κB (IκB), which inhibits NF-κB nuclear translocation, abolished senescence bypass, suggesting that the inhibitory effect of IKKβ-CA on senescence is largely mediated by NF-κB. We also found that IKKβ-CA expression suppressed the derepression of INK4/Arf genes and counteracted the senescence-associated loss of Ezh2, a catalytic subunit of the Polycomb repressive complex 2 (PRC2). Moreover, pharmacological inhibition of Ezh2 abolished IKKβ-CA-induced senescence bypass. We propose that NF-κB plays a suppressive role in the induction of stress-induced senescence through sustaining Ezh2 expression.

Protective Actions of Cannabidiol on Aging-Related Inflammation, Oxidative Stress and Apoptosis Alterations in Liver and Lung of Long Evans Rats

BACKGROUND

Aging is characterised by the progressive accumulation of oxidative damage which leads to inflammation and apoptosis in cells. This affects all tissues in the body causing the deterioration of several organs. Previous studies observed that cannabidiol (CBD) could extend lifespan and health span by its antioxidant, anti-inflammatory and autophagy properties. However, research on the anti-aging effect of CBD is still in the beginning stages. This study aimed to investigate the role of cannabidiol (CBD) in the prevention of age-related alterations in liver and lung using a murine model.

METHODS

15-month-old Long Evans rats were treated with 10 mg/kg b.w./day of CBD for 10 weeks and compared to animals of the same age as old control and 2-month-old animals as young control. Gene and/or protein expressions, by RT-qPCR and Western blotting, respectively, were assessed in terms of molecules related to oxidative stress (GST, GPx, GR and HO-1d), inflammation (NFκB, IL-1β and TNF-α) and apoptosis (BAX, Bcl-2, AIF, and CASP-1). In addition, MDA and MPO levels were measured by colorimetric assay. Results were analysed by ANOVA followed by Tukey-Kramer test, considering statistically significant a p < 0.05.

RESULTS

GST, GPx and GR expressions were significantly reduced (p < 0.01) in liver samples from old animals compared to young ones and CBD treatment was able to revert it. A significant increase was observed in old animals compared to young ones in relation to oxidative stress markers (MDA and HO-1d), proinflammatory molecules (NFκB, IL-1β and TNF-α), MPO levels and proapoptotic molecules (BAX, AIF and CASP-1), while no significant alterations were observed in the antiapoptotic molecules (Bcl-2). All these changes were more noticeable in the liver, while the lung seemed to be less affected. In almost all the measured parameters, CBD treatment was able to revert the alterations caused by age restoring the levels to those observed in the group of young animals.

CONCLUSIONS

Chronic treatment with CBD in 15-month-old rats showed beneficial effects in lung and more significantly in liver by reducing the levels of inflammatory, oxidative and apoptotic mediators, and hence the cell damage associated with these three processes inherent to aging.

S100s and HMGB1 Crosstalk in Pancreatic Cancer Tumors

Pancreatic cancer remains a disease that is very difficult to treat. S100 proteins are small calcium binding proteins with diverse intra- and extracellular functions that modulate different aspects of tumorigenesis, including tumor growth and metastasis. High mobility group box 1 (HMGB1) protein is a multifaceted protein that also actively influences the development and progression of tumors. In this study, we investigate the possible correlations, at the transcript level, between S100s and HMGB1 in pancreatic cancer. For this purpose, we calculated Pearson's correlations between the transcript levels of 13 cancer-related S100 genes and HMGB1 in a cDNA array containing 19 pancreatic cancer tumor samples, and in 8 human pancreatic cancer cell lines. Statistically significant positive correlations were found in 5.5% (5 out of 91) and 37.4% (34 of 91) of the possible S100/S100 or S100/HMGB1 pairs in cells and tumors, respectively. Our data suggest that many S100 proteins crosstalk in pancreatic tumors either with other members of the S100 family, or with HMGB1. These newly observed interdependencies may be used to further the characterization of pancreatic tumors based on S100 and HMGB1 transcription profiles.