Discovery and identification of Serum Amyloid A protein elevated in lung cancer serum

Two hundred and eighteen serum samples from 175 lung cancer patients and 43 healthy individuals were analyzed by using Surface Enhaced Laser Desorption/Ionization Time of Flight Mass Spectrome- try (SELDI-TOF-MS). The data analyzed by both Biomarker Wizard? and Biomarker Patterns? software showed that a protein peak with the molecular weight of 11.6 kDa significantly increased in lung cancer. Meanwhile,the level of this biomarker was progressively increased with the clinical stages of lung cancer. The candidate biomarker was then obtained from tricine one-dimensional sodium dodecyl sul- fate-polyacrylamide gel electrophoresis by matching the molecular weight with peaks on WCX2 chips and was identified as Serum Amyloid A protein (SAA) by MALDI/MS-MS and database searching. It was further validated in the same serum samples by immunoprecipitation with commercial SAA antibody. To confirm the SAA differential expression in lung cancer patients, the same set of serum samples was measured by ELISA assay. The result showed that at the cutoff point 0.446(OD value)on the Receiver Operating Characteristic (ROC) curve, SAA could better discriminate lung cancer from healthy indi- viduals with sensitivity of 84.1% and specificity of 80%. These findings demonstrated that SAA could be characterized as a biomarker related to pathological stages of lung cancer.

The relationship between serum amyloid A and apolipoprotein A-I in high-density lipoprotein isolated from patients with coronary heart disease

Background Alteration in the protein composition of high-density lipoprotein （HDL） has been proposed as a mechanism for the development of coronary heart disease （CHD）.In HDL,an increase in serum amyloid A protein （SAA） accompanying the decrease in apolipoprotein A-I （apoA-I） has been found during the acute inflammation period.However,whether this phenomenon persists in CHD patients,a disease related to inflammation,is unknown.The purpose of the present study was to explore the relationship between SAA and apoA-I in HDL isolated from CHD patients.Methods Overall,98 patients with confirmed stable CHD and 90 control subjects matched for age and gender were enrolled in this case-control study.Potassium bromide （KBr） density gradient ultracentrifugation was used to isolate HDL from plasma.The levels of SAA and apoA-I in the HDL samples were detected by enzyme-linked immunosorbent assay kits.Pearson＇s correlation and general linear models were used in the analysis.Results Compared with controls,patients with CHD had a significant decrease in the amount of apoA-I （（14.21±8.44） μg/ml vs.（10.95±5.95） μg/ml,P =0.003） in HDL and a significant increase in the amount of log SAA （1.21±0.46 vs.1.51±0.55,P 〈0.00001）.Differences were independent of age,body mass index （BMI）,HDL cholesterol （HDL-C）,and other factors.An independently and statistically significant positive correlation between log SAA and apoA-I in HDL was observed only in the CHD group （β =2.0,P =0.026）.In the general linear model,changes in Iog（SAA）,age,age2,gender,BMI and HDL-C could explain a statistically significant 43% of the variance in apoA-I.Conclusions This study provides direct evidence for the first time that there was an independent positive correlation between log SAA and apoA-I in the HDL of CHD patients,indicating the alteration of protein composition in HDL.However,the question of whether this alteration in HDL is associated with impairment of HDL functions requires further research.

Ischemic stroke susceptibility gene in a Northern Han Chinese population

Interleukin-18 gene promoter polymorphisms are potential risk factors for ischemic cerebrovascular disease, and the –607C allele may increase ischemic stroke risk in the Han Chinese population. In the present study, we recruited 291 patients with ischemic cerebrovascular disease from the Affiliated Hospital of Qingdao University Medical College, China, and 226 healthy controls. Both patients and controls were from the Han population in northern China. Immunoresonance scattering assays detected increased serum amyloid A protein, C-reactive protein, and interleukin-18 levels in ischemic cerebrovascular disease patients compared with healthy controls. Analysis of the –607C/A （rs1946518） polymorphism in the interleukin-18 gene promoter showed ischemic cerebrovascular disease patients exhibited increased frequencies of the CC genotype and C alleles than healthy controls. Genotype and allele frequencies of the interleukin-18 –137G/C （rs187238） polymorphism and the –13T/C （rs11024595） polymorphism in the 5＇-flanking region of serum amyloid A, showed no significant difference between the two groups. Multivariate logistic regression analysis on the interleukin-18 promoter A/C genetic locus, for correction of age, gender, history of smoking, hypertension, diabetes mellitus, hypercholesteremia, and an ischemic stroke family history, showed ischemic cerebrovascular disease risk in individuals without the A allele （C homozygotes） was 2.2-fold greater than in A allele carriers. Overall, our findings suggest that the –13T/C （rs11024595） polymorphism in the 5′-flanking region of serum amyloid A has no correlation with ischemic cerebrovascular disease, but the C allele of the –607C/A （rs1946518） polymorphism in the interleukin-18 promoter is a high-risk factor for ischemic cerebrovascular disease in the Han population of northern China. In addition, the A allele is likely a protective gene for ischemic cerebrovascular disease.