Paradoxical effects of cellular senescence-inhibited gene involved in hepatocellular carcinoma migration and proliferation by ERK pathway and mesenchymal-like markers.

Background: Cellular senescence-inhibited gene (CSIG) strongly prolongs the progression of replicative senescence. However, roles and mechanisms of CSIG in tumor progression have not been studied widely.

Methods: Roles of CSIG in migration and proliferation of SMMC7721 and Huh7 cells were analyzed by transwell or cell viability assays, respectively.

Real-Time Detection Reveals Responsive Cotranscriptional Formation of Persistent Intramolecular DNA and Intermolecular DNA:RNA Hybrid G-Quadruplexes Stabilized by R-Loop.

G-quadruplex (GQ) structures are implicated in important physiological and pathological processes. Millions of GQ-forming motifs are enriched near transcription start sites (TSSs) of animal genes. Transcription can induce the formation of GQs, which in turn regulate transcription.

Age-dependent accumulation of mitochondrial DNA deletions in the aortic root of atherosclerosis-prone apolipoprotein E-knockout mice.

Purpose: To investigate whether mitochondrial DNA (mtDNA) damage, specifically deletion, contributes to the development of atherosclerosis or is simply a secondary effect of the primary factors causing atherosclerosis.

Materials And Methods: mtDNA deletion was detected by PCR in the aortic root of atherosclerosis-prone C57BL/6J apolipoprotein (Apo) E gene deficient (-/-) mice and control C57BL/6J mice at different ages. Atherosclerotic plaques in the Apo E-/- mice were assessed using frozen sections of the aortic root.

[Comparison of Southern blotting and Real-time PCR in measuring telomere shortening].

Objective: To analyze and compare the performances of two telomere measurement methods (digoxigenin-labeled Southern blot and Real-time PCR) in cellular senescence research.

Methods: Genomic DNA extracted from normal human fibroblasts (2BS) of different population doublings (PDs) was used as test samples. The Southern blot and Real-time PCR methods for telomere measurements were optimized.

Hydrogen peroxide induces p16(INK4a) through an AUF1-dependent manner.

Elevation of p16(INK4a) has been described as an important mechanism for hydrogen peroxide (H2O2)-induced replicative senescence. However, the mechanisms underlying remain unknown. In this study, we demonstrate an important role of RNA-binding protein AUF1-mediated mRNA turnover in H2O2-induced p16(INK4a) expression.

Age-dependent down-regulation of mitochondrial 8-oxoguanine DNA glycosylase in SAM-P/8 mouse brain and its effect on brain aging.

Mitochondrial DNA (mtDNA) damage has been hypothesized to be responsible for aging and various neurological diseases. Abnormalities in 8-oxoguanine DNA glycosylase (OGG1) function can promote DNA oxidative damage, especially in the mitochondria. Here we report changes in the expression of OGG1 targeting to the nucleus, cytosol, and mitochondria in both accelerated senescence mice (SAM-P/8) and normal counterpart SAM-R/1 mice during brain aging.

Two isomers of HDTIC isolated from Astragali Radix decrease the expression of p16 in 2BS cells.

Background: Astragali Radix, the root of Astragalus membranceus (Fish) Bunge Var. mongholicus (Bge), is a crude drug considered as one of the effective traditional Chinese anti-ageing material. The two isomers of 4-hydroxy-5-hydroxymethyl-[1, 3] dioxolan-2, 6'-spirane-5', 6', 7', 8'-tetrahydro-indolizine-3'-carbaldehyde (HDTIC), HDTIC-1 and HDTIC-2, were first extracted from the herb in 2002.

Aminoguanidine delays the replicative senescence of human diploid fibroblasts.

Background: The accumulation of free radicals and advanced glycation end products (AGEs) in cell plays a very important role in replicative senescence. Aminoguanidine (AG) has potential antioxidant effects and decreases AGE levels. This study aimed to investigate its effect on replicative senescence in vitro.

Optimization of reporter gene assay: several factors influencing detection of promoter activity.

Background: Promoter analysis is currently applied to detect the expression of the targeted gene in studies of signal transduction and transcriptional regulation. As a reporter gene, luciferase plays an important role and has been used widely in the promoter assay.

Methods: Human embryonic lung fibroblast cells (2BS), HeLa cells and MCF-7 cells were transfected with various genes embedded by lipofectamine.

[Mechanisms of aging and its theories].

The velocity of aging is rather different in various species, and even in various tissues and cells of the same individual. Both genetic and environmental factors affect aging process. It is evident that life expectancy mainly relates to environment, while maximum life-span of a species more depends on its genetic background.

Posttranscriptional induction of p21Waf1 mediated by ectopic p16INK4 in human diploid fibroblast.

Background: Both p16(INK4) and p21(Waf1) are tumor suppressors with similar biological functions in the regulation of cellular senescence. Previous reports showed that p16(INK4) could be activated by p21(Waf1) through transcriptional factor Sp1 in HeLa cells. This study was undertaken to determine the effects of p16(INK4) on the expression and functions of p21(Waf1).

p21Waf1/Cip1 plays a critical role in modulating senescence through changes of DNA methylation.

It has been reported that genomic DNA methylation decreases gradually during cell culture and an organism's aging. However, less is known about the methylation changes of age-related specific genes in aging. p21(Waf1/Cip1) and p16(INK4a) are cyclin-dependent kinase (Cdk) inhibitors that are critical for the replicative senescence of normal cells.

Down-regulation of p21WAF1 promotes apoptosis in senescent human fibroblasts: involvement of retinoblastoma protein phosphorylation and delay of cellular aging.

It has been suggested that genes which exercise checkpoint control during cell cycle traverse are equally important to the process of apoptotic cell death. In this study, we show that the key cell cycle regulatory gene p21(WAF1) is also involved in the execution of apoptosis. p21(WAF1) expression was down-regulated during NaBu-induced apoptosis of senescent normal diploid human 2BS fibroblasts.

Telomere Shortening of MCF-7 Cells Caused by Antisense Telomerase cDNA.

pAdE(1)CMVITREXneo is a novel adenovirus vector which can integrate foreign genes into genome of host cells. The cDNA of human telomerase RNA was integrated inversely into the vector via antisense oligonucleotide technique. Antisense recombinant virus (vAdT-AAV) was obtained by cotransfecting pAdT and pBHG(11) into 293 cells.

Exogenous p21(WAF1) Transfection Affects Apoptosis in Human Fibroblasts.

pDOR-p21 sense and pDOR-p21 antisense retroviral expression vectors were constructed and successfully transfected by Lipofectin into normal human diploid fibroblasts(2BS line), resulting in 2BS-p21s and 2BS-p21a cell lines, respectively. Southern blot analysis verified that the exogenous p21(WAF1) cDNA were integrated into genomic DNA. Compared with the cells transfected with pDOR-neo empty vector, p21(WAF1) mRNA expression increased in 2BS-p21s cells, which were less sensitive to apoptosis induced by NaBu, and showed higher cell viability, delayed appearance of DNA ladder, and less area of apoptosis peak.

Antisense c-erbB-2 Decreases DNA Repair and Apoptosis Inducibility in Human Diploid Fibroblasts.

pDOR-erbB-2 sense and antisense retroviral expression vectors were introduced into normal human diploid fibroblasts(2BS), respectively, to construct 2BS-A cells(transfected with antisense recombinant vector) and 2BS-S cells (transfected with sense recombinant vector). Southern blot analysis verified that the exgenous c-erbB-2 cDNA were integrated into genomic DNA. Compared with the cells transfected with pDOR-neo empty vector, 2BS-A cells exhibited decreased ability not only to repair DNA damage, but also to undergo apoptosis.