Objective To investigate the effects of oxidative stress and lipoic acid(antioxidant)on bone metabolism and explore the underlying mechanism. Methods A total of 24 Wistar rats aged 8 weeks were randomly divided into three groups. Osteoporosis rats model was established by bilateral ovaries deleted. Rat in lipoic acid group was injected with lipoic acid(60 mg/kg)for 8 weeks. The bone mineral density(BMD),steo?calcin,ALP,Ca,P,MDA,SOD and GSH?Px were detected. The levels of OPG and RANKL in serum were measured by Western blotting. OPG and RANKL mRNA were detected by real?time PCR. Results The level of BMD level in blood,SOD,GSH?Px,OPG mRNA and protein level in femur of osteoporosis group were significantly lower than the control group(P<0.05). On the other hand,steocalcin,ALP,MDA,RANKL mRNA and protein level were significantly higher than the control group(P<0.05). The level of BMD level in blood,SOD,GSH?Px,OPG mRNA and protein level of lipoic acid group were significantly higher than the osteoporosis group(P<0.05). The steocalcin,ALP,MDA,RANKL mRNA and protein level were significantly lower than the osteoporosis group(P<0.05). Conclusion Oxidative stress may increase osteoporosis through the upregulation of OPG/RANKL pathway in rats ,and antioxidant lipoic acid can alleviate the progress of osteoporosis.

BACKGROUNDRecently, the p14 ARF gene has emerged as a new putative tumor suppressor gene, and the alteration of p14 ARF gene is closely related to development of multiple human tumors. The aberrant promoter methylation as a mechanism of inactivation of p14 ARF gene might participate in tumorigenesis. The aim of this study is to investigate promoter methylation status and protein expression of p14 ARF gene in pulmonary squamous cell carcinoma and adenocarcinoma, and to value the role of p14 ARF promoter methylation in carcinogenesis of non-small cell lung cancer.

METHODSPromoter methylation status and protein expression of p14 ARF gene were analyzed in 40 cases of pulmonary squamous cell carcinoma and adenocarcinoma by methylation specific polymerase chain reaction (MSP), restriction enzyme-related polymerase chain reaction (RE-PCR) and immunohistochemistry (IHC).

RESULTSThe positive rate of p14 ARF promoter methylation in tumor tissues and normal tissues adjacent to cancer was 17.5% (7/40) and 2.5% (1/40) respectively (P= 0.025 ). The results of RE-PCR were consistent with the above. The positive rate of p14 ARF protein in tumor tissues was significantly lower than that in normal tissues adjacent to cancer (P=0.003). Promoter methylation and protein expression of p14 ARF gene showed a significantly negative correlation (r=-0.56, P= 0.001 ), and both of them did not correlate statistically with the clinicopathologic characteristics of patients such as histological classification, TNM stages, differentiation grade and lymph node involvement.

CONCLUSIONSPromoter methylation is a crucial mechanism of inactivation of p14 ARF gene. Promoter methylation of p14 ARF gene might be involved in carcinogenesis of non-small cell lung cancer, and it is an early event in development process of non-small cell lung cancer.