[Activation of nuclear factor-κB subunit p50/p65 enhances gefitinib resistance of lung adenocarcinoma H1650 cell line].

OBJECTIVE: To explore the intrinsic connection between activation of classical nuclear factor-κB (NF-κB) pathway and gefitinib resistance in human lung adenocarcinoma H1650 cells. METHODS: Human lung adenocarcinoma H1650 cells were exposed to gefitinib continuously for 60 days to obtain resistant H1650 cells. The expressions of P-IκBα, P-p50 and P-p65 in the cytoplasm or nuclei were detected using Western blotting in human lung adenocarcinoma HCC827 cells, parental H1650 cells and gefitinib-resistant H1650 cells. The effects of gefitinib alone or in combination with PDTC on the survival rate and expressions of NF-κB P-p50 and P-p65 were compared among the 3 cell lines. RESULTS: Gefitinib-resistant H1650 cells showed increased cytoplasmic and nuclear P-IκBα expressions. The expressions of P-p50 and P-p65 differed significantly among the 3 cell line, decreasing in the order of resistant H1650 cells, parental H1650 cells, and gefitinib sensitive HCC827 cell lines (P<0.05 or 0.01). Treatment with gefitinib alone resulted in a significantly lower cell inhibition rate in resistant H1650 cells than in the parental H1650 cells (P<0.05) and HCC827 cells (P<0.01). The resistant H1650 cells had a significantly higher expression of P-p50 and P-p65 than other two cell lines (P<0.05). In both the resistant and parental H1650 cells, gefitinib significantly lowered P-p50 and P-p65 expressions (P<0.05 or 0.01), and the combined treatment with gefitinib and PDTC significantly decreased the cell survival rate and further lowered the cytoplasmic and nuclear expressions of P-p50 and P-p65 (P<0.01 or 0.01). CONCLUSION: The activation of classical NF-κB pathway is a key factor contributing to transformation of the parental H1650 cells into gefitinib-resistant cells. Gefitinib combined with PDTC can inhibit P-IκBα production and NF-κB P-p50 and P-p65 activation to suppress the survival of residual H1650 cells and the generation of gefitinib-resistant cells.

[Preliminary study on single nucleotide polymorphisms and linkage disequilibrium in promoter region of fibrinogen B beta gene].

OBJECTIVE: To investigate the distribution characters and linkage disequilibrium of single nucleotide polymorphisms (SNPs) -148C/T, -455G/A and -854G/A in the promoter region of fibrinogen B(FGB) beta gene. METHODS: Genotype and allele frequencies of FGB beta gene were examined by polymerase chain reaction-restriction fragment length polymorphism and nucleotide sequencing methods in 377 Chinese southern Han individuals. Three FGB beta SNPs Hardy-Weinberg equilibrium and linkage disequilibrium were analyzed with population genetics methods. RESULTS: The allele frequencies of 3 SNPs are in good agreement with Hardy-Weinberg equilibrium. A total of 9 genotypes among the 377 individuals were identified in 3 SNPs. The genotype frequencies of -148CC, CT and TT were 0.597, 0.358 and 0.045, respectively; the -455G/A genotype frequencies were the same as that of -148C/T SNP; the genotype frequencies of -854GG,GA, AA were 0.820,0.178,0.002, respectively. The frequencies of rare allele -148T, -455A and -854A were 0.224,0.224 and 0.092, respectively, while the common allele frequencies were 0.776 for -148C, 0.776 for -455G, and 0.908 for -854G. There were no statistically significant differences in genotype and allele frequencies between the male and female groups (P>0.05). The relationship between -455G and -148C was completely concordant, but there was a random distribution between -854 and -148 (-445) SNPs. CONCLUSION: The results show there is a complete linkage disequilibrium between -148C/T and -455G/A and a negative linkage disequilibrium between -854G/A and -148C/T, as well as between -854G/A and -455G/A. This study has provided population genetics data on FGB beta gene promoter in Chinese southern Han population.