Associations Between Snps In The TGF-β Signaling Pathway And Risk Of Brain Metastasis In Patients With NSCLC And Functional Verification

Purpose:Brain metastasis (BM) from non-small cell lung cancer (NSCLC) is relatively common, but identifying which patients will develop brain metastasis has been problematic. We hypothesized that genotype variants in the TGF-β/Smad signaling pathway could be a predictive biomarker of brain metastasis.Patients and methods:We genotyped33SNPs from13genes in the TGF-β/Smad signaling pathway and evaluated their associations with brain metastasis risk by using DNA from blood samples from161patients with NSCLC. Kaplan-Meier analysis was used to assess brain metastasis risk; Cox hazard analyses were used to evaluate the effects of various patient and disease characteristics on the risk of brain metastasis.Results:The median age of the116men and45women in the study was58years;62(39%) had stage IIIB or IV disease. Within24months after initial diagnosis of lung cancer, brain metastasis was found in60patients (37%). Of these60patients,16had presented with BM at diagnosis. Multivariate analysis showed the GG genotype of SMAD6:rs12913975and TT genotype of INHBC:rs4760259to be associated with a significantly higher risk of brain metastasis at24months follow-up (hazard ratio [HR]2.540,95%confidence interval [CI]1.204-5.359, P=0.014; and HR1.885,95%CI1.086-3.273, P=0.024), compared with the GA or CT/CC genotypes, respectively. When analyze combined subgroups, these rates showed higher for those having both the GG genotype of SMAD6:rs12913975and the TT genotype of INHBC:rs4760259(HR2.353,95%CI1.390-3.985, P=0.001).Conclusions:We found the GG genotype of SMAD6:rs12913975and TT genotype of INHBC:rs4760259to be associated with risk of brain metastasis in patients with NSCLC. This finding, if confirmed, can help to identify patients at high risk of brain metastasis. Purpose:Non-small cell lung cancer (NSCLC) metastasizes fairly often to the brain, but identifying which patients will develop brain metastases (BM) is problematic. The phosphatidylinositol-3kinase (PI3K)-AKT-mammalian target of rapamycin (mTOR) signaling pathway is important in the control of cell growth, tumorigenesis, and cell invasion. We hypothesized that genotype variants in this pathway could predict BM in patients with NSCLC.Methods:We genotyped16single nucleotide polymorphisms (SNPs) in5core genes (PIK3CA, PTEN, AKT1, AKT2, and FRAP1) by using DNA from blood samples of317patients with NSCLC and evaluated potential associations with the subsequent development of BM, the cumulative incidence of which was estimated with Kaplan-Meier analysis. Multivariate Cox regression analysis was used to analyze correlations between genotype variants and the occurrence of BM.Results:In analysis of individual SNPs, the GT/GG genotype of AKT1:rs2498804, CT/TT genotype of AKT1:rs2494732and AG/AA genotype of PIK3CA:rs2699887were associated with higher risk of BM at24months’follow-up (respective hazard ratios [HRs]1.860,95%confidence interval [CI]1.199-2.885, P=0.006; HR1.902,95%CI1.259-2.875, P=0.002; and HR1.933,95%CI1.168-3.200, P=0.010). We further found that these SNPs had a cumulative effect on BM risk, with that risk being highest for patients carrying both of these unfavorable genotypes (P=0.003).Conclusions:Confirmation of our findings, the first to indicate that genetic variations in PI3K-AKT-mTOR can predict BM, in prospective studies would facilitate stratification of patients for BM prevention trials. Purpose:Brain metastases from Non-small cell lung cancer (NSCLC) is relatively common and prognosis is very poor, but identifying which patients will develop brain metastases (BM) is problematic. Akt, a Serine/Threonine protein kinase, mediates growth factor associated cell survival. Constitutive activation of Akt (phosphorylated Akt, P-Akt) has been observed in several human cancers, including lung cancer and may be associated with poor prognosis. We hypothesized that the P-Akt level was association with AKT genotype and could predict BM in patients with NSCLC.Methods:In the present study, we examined99surgically resected paraffin-embedded NSCLC samples for P-Akt by immunohistochemistry. We evaluated potential associations with the subsequent development of BM, the cumulative incidence of which was estimated with Kaplan-Meier and Log-rank analysis. Cox regression analysis was used to analyze correlations between Akt expression level and the occurrence of BM. Chi-square test (Phicorrelation) analysis the relationship between the expression level and AKT genotype.Results:CytoplasmicP-Akt (CP-Akt) tumor cell staining was detected in67%of cases. Only one case has been detected nucleus dyeing. Kaplan-Meier and Log-rank test found that the high P-Akt express level was associated with higher risk of BM at24months’ follow-up (P=0.018). We further found that the P-Akt expression level is higher in AKT1: rs2498804GT/GG and AKT1:rs2494732CT/TT genotype patients than in patients with the TT and CC genotype patients, but the difference did not reach statistical significance.Conclusions:These results indicate that P-Akt expression level is vary in different genotype of AKT. And the high level of P-Akt protein is was associated with increased risk of BM. This conclusion, if can be confirmed by large sample research, may help us to better identify people at high risk of brain metastases from non-small cell lung cancer.