Abstract. Although tobacco and alcohol consumption are the major risk factors of head and neck cancer (HNC), genetic variations of genes involved in several biological pathways, such as DNA repair genes, may affect an individual's susceptibility to HNC. However, few studies have investigated the associations between polymorphisms in DNA repair genes and HNC risk in the Chinese population. Thus, we genotyped five common, non-synonymous single-nucleotide polymorphisms (SNPs) [APEX1 (Asp148Glu), XRCC1 (Arg399Gln), ADPRT (Val762Ala), XPD (Lys751Gln) and XPG (His1104Asp)] in a hospital-based, case-control study of 397 HNC cases and 900 cancer-free controls in China. The results showed that none of the five SNPs in the DNA repair pathway was significantly associated with HNC risk, suggesting that these polymorphisms may not play a major role in HNC susceptibility in this Chinese population. IntroductionThe incidence of head and neck cancer (HNC), especially squamous cell carcinoma of the head and neck (SCCHN), has markedly increased in the past 20 years and is now the fifth most common type of cancer worldwide (1). In the United States, it is estimated that there were 48,010 new cases and 11,260 deaths from SCCHN in 2010 (2). Accumulative evidence indicates that exposure to smoking and alcohol consumption are important risk factors of HNC (3); however, only few smokers and drinkers develop HNC, suggesting an individual susceptibility to this cancer in the general population. Most association studies on cancer susceptibility have focused on identifying effects of single-nucleotide polymorphisms (SNPs) in candidate genes of several pathways. Among these, genes involved in the DNA repair pathway are the most investigated due to their vital role in protecting the genome from insults of environmental carcinogens (4,5). Studies have shown inter-individual variations of DNA repair capacity (DRC) in the general population and the effect of a suboptimal DRC on the risk of smoking-related cancers, such as lung cancer and SCCHN (6-8).Of DNA repair pathways, nucleotide excision repair (NER) is the major repair mechanism for the DNA damage caused by tobacco smoking, which deals with a wide class of DNA damages, including bulky adducts cross-links, oxidative DNA damage, thymidine dimers and alkylating damage (9). NER involves more than 20 proteins whose inactivation may lead to xeroderma pigmentosum (XP) or Cockayne syndrome (CS). For example, rare mutations in xeroderma pigmentosum complementation group D and G (XPD and XPG) give rise to a combined XP/CS phenotype and are associated with severe neurological abnormalities.The base excision repair (BER) pathway is another important mechanism that repairs DNA damage resulting from chemical alterations of a single base; a number of proteins are involved in repair steps, such as apurinic/apyrimidinic endonuclease (APE1, also known as APEX1), X-ray repair crosscomplementing 1 (XRCC1) and ADP-ribosyltransferase (ADPRT, also known as PARP1) (10). APE1 is a key member in short-patch BER, w...
Hypoxic pulmonary vascular remodelling (PVR) is the major pathological basis of aging-related chronic obstructive pulmonary disease and obstructive sleep apnea syndrome. The pulmonary artery endothelial cell (PAEC) inflammation, and pulmonary artery smooth muscle cell (PASMC) proliferation, hypertrophy and collagen remodelling are the important pathophysiological components of PVR. Endogenous sulfur dioxide (SO2) was found to be a novel gasotransmitter in the cardiovascular system with its unique biological properties. The study was aimed to investigate the role of endothelial cell- (EC-) derived SO2 in the progression of PAEC inflammation, PASMC proliferation, hypertrophy and collagen remodelling in PVR and the possible mechanisms. EC-specific aspartic aminotransferase 1 transgenic (EC-AAT1-Tg) mice were constructed in vivo. Pulmonary hypertension was induced by hypoxia. Right heart catheterization and echocardiography were used to detect mouse hemodynamic changes. Pathologic analysis was performed in the pulmonary arteries. High-performance liquid chromatography was employed to detect the SO2 content. Human PAECs (HPAECs) with lentiviruses containing AAT1 cDNA or shRNA and cocultured human PASMCs (HPASMCs) were applied in vitro. SO2 probe and enzyme-linked immunosorbent assay were used to detect the SO2 content and determine p50 activity, respectively. Hypoxia caused a significant reduction in SO2 content in the mouse lung and HPAECs and increases in right ventricular systolic pressure, pulmonary artery wall thickness, muscularization, and the expression of PAEC ICAM-1 and MCP-1 and of PASMC Ki-67, collagen I, and α-SMA ( p < 0.05 ). However, EC-AAT1-Tg with sufficient SO2 content prevented the above increases induced by hypoxia ( p < 0.05 ). Mechanistically, EC-derived SO2 deficiency promoted HPAEC ICAM-1 and MCP-1 and the cocultured HPASMC Ki-67 and collagen I expression, which was abolished by andrographolide, an inhibitor of p50 ( p < 0.05 ). Meanwhile, EC-derived SO2 deficiency increased the expression of cocultured HPASMC α-SMA ( p < 0.05 ). Taken together, these findings revealed that EC-derived SO2 inhibited p50 activation to control PAEC inflammation in an autocrine manner and PASMC proliferation, hypertrophy, and collagen synthesis in a paracrine manner, thereby inhibiting hypoxic PVR.
Liver is a vital organ with many important functions, and the maintenance of normal hepatic function is necessary for health. As an essential mechanism for maintaining cellular homeostasis, autophagy plays an important role in ensuring normal organ function. Studies have indicated that the degeneration of hepatic function is associated with autophagic deficiency in aging liver. However, the underlying mechanisms still remain unclear. The serine protease Omi/HtrA2 belongs to the HtrA family and promotes apoptosis through either the caspase-dependent or caspase-independent pathway. Mice lacking Omi/HtrA2 exhibited progeria symptoms (premature aging), which were similar to the characteristics of autophagic insufficiency. In this study, we demonstrated that both the protein level of Omi/HtrA2 in liver and hepatic function were reduced as rats aged, and there was a positive correlation between them. Furthermore, several autophagy-related proteins (LC3II/I, Beclin-1 and LAMP2) in rat liver were decreased significantly with the increasing of age. Finally, inhibition of Omi/HtrA2 resulted in reduced autophagy and hepatic dysfunction. In conclusion, these results suggest that Omi/HtrA2 participates in age-related autophagic deficiency in rat liver. This study may offer a novel insight into the mechanism involved in liver aging.
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