Browsing by Author "Zhu, Ji"
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Item Open Access Component-wise gradient boosting and false discovery control in survival analysis with high-dimensional covariates.(Bioinformatics, 2016-01-01) He, Kevin; Li, Yanming; Zhu, Ji; Liu, Hongliang; Lee, Jeffrey E; Amos, Christopher I; Hyslop, Terry; Jin, Jiashun; Lin, Huazhen; Wei, Qinyi; Li, YiMOTIVATION: Technological advances that allow routine identification of high-dimensional risk factors have led to high demand for statistical techniques that enable full utilization of these rich sources of information for genetics studies. Variable selection for censored outcome data as well as control of false discoveries (i.e. inclusion of irrelevant variables) in the presence of high-dimensional predictors present serious challenges. This article develops a computationally feasible method based on boosting and stability selection. Specifically, we modified the component-wise gradient boosting to improve the computational feasibility and introduced random permutation in stability selection for controlling false discoveries. RESULTS: We have proposed a high-dimensional variable selection method by incorporating stability selection to control false discovery. Comparisons between the proposed method and the commonly used univariate and Lasso approaches for variable selection reveal that the proposed method yields fewer false discoveries. The proposed method is applied to study the associations of 2339 common single-nucleotide polymorphisms (SNPs) with overall survival among cutaneous melanoma (CM) patients. The results have confirmed that BRCA2 pathway SNPs are likely to be associated with overall survival, as reported by previous literature. Moreover, we have identified several new Fanconi anemia (FA) pathway SNPs that are likely to modulate survival of CM patients. AVAILABILITY AND IMPLEMENTATION: The related source code and documents are freely available at https://sites.google.com/site/bestumich/issues. CONTACT: yili@umich.edu.Item Open Access Genetic polymorphisms of PAI-1 and PAR-1 are associated with acute normal tissue toxicity in Chinese rectal cancer patients treated with pelvic radiotherapy.(OncoTargets and therapy, 2015-01) Zhang, Hui; Wang, Mengyun; Shi, Tingyan; Shen, Lijun; Zhu, Ji; Sun, Menghong; Deng, Yun; Liang, Liping; Li, Guichao; Wu, Yongxin; Fan, Ming; Wei, Qingyi; Zhang, ZhenPlasminogen activator inhibitor type 1 (PAI-1) and protease-activated receptor-1 (PAR-1) are crucial mediators of the intestinal microenvironment and are involved in radiation-induced acute and chronic injury. To evaluate whether genetic polymorphisms of PAI-1 and PAR-1 were predictors of radiation-induced injury in patients with rectal cancer, we retrospectively evaluated 356 rectal cancer patients who had received pelvic radiotherapy and analyzed the association of genetic polymorphisms of PAI-1 and PAR-1 with acute toxicities after radiotherapy. Acute adverse events were scored, including dermatitis, fecal incontinence (anal toxicity), hematological toxicity, diarrhea, and vomiting. The patients were grouped into grade ≥2 and grade 0-1 toxicity groups to analyze the acute toxicities. Genotyping of six single nucleotide polymorphisms (SNPs) of PAI-1 and PAR-1 was performed using TaqMan assays. A logistic regression model was used to estimate the odds ratios and 95% confidence intervals. Of the 356 individuals, 264 (72.5%) had grade ≥2 total toxicities; within this group, there were 65 (18.3%) individuals who reached grade ≥3 toxicities. There were 19.5% (69/354) and 36.9% (130/352) patients that developed grade ≥2 toxicities for diarrhea and fecal incontinence, respectively. The variant genotype GG of rs1050955 in PAI-1 was found to be negatively associated with the risk of diarrhea and incontinence (P<0.05), whereas the AG and GG genotypes of rs2227631 in PAI-1 were associated with an increased risk of incontinence. The CT genotype of PAR-1 rs32934 was associated with an increased risk of total toxicity compared with the CC allele. Our results demonstrated that SNPs in the PAI-1 and PAR-1 genes were associated with acute injury in rectal cancer patients treated with pelvic irradiation. These SNPs may be useful biomarkers for predicting acute radiotoxicity in patients with rectal cancer if validated in future studies.Item Open Access TNF rs1799964 as a Predictive Factor of Acute Toxicities in Chinese Rectal Cancer Patients Treated With Chemoradiotherapy.(Medicine, 2015-11) Zhang, Hui; Wang, Mengyun; Shi, Tingyan; Shen, Lijun; Liang, Liping; Deng, Yun; Li, Guichao; Zhu, Ji; Wu, Yongxin; Fan, Ming; Deng, Weijuan; Wei, Qingyi; Zhang, ZhenAcute toxicity is the main dose-limiting factor in the chemoradiotherapy of rectal cancer patients and depends on several pro-inflammatory factors, including interleukin-1 (IL-1), IL-6, and tumor necrosis factor-alpha (TNF-α). It is unknown whether genetic factors, such as single-nucleotide polymorphisms (SNPs) in the IL-1, IL-6, and TNF genes, are also associated with acute toxicity in the process.We genotyped 5 potentially functional SNPs in these 3 genes (TNF rs1799964, TNF rs1800629, IL-6 rs1800796, and IL-1 rs1143623, IL-1 rs1143627) and estimated their associations with severe acute radiation injury (grade ≥2) in 356 rectal cancer patients.We found a predictive role of the TNF rs1799964 T variant allele in the development of acute injury (for CT vs CC: adjusted odds ratio [OR] = 4.718, 95% confidence interval [CI] = 1.152-19.328, P = 0.031; for TT vs CC: adjusted OR = 4.443, 95% CI = 1.123-17.581, P = 0.034). In the dominant model, for CT/TT vs CC, the adjusted OR = 4.132, 95% CI = 1.069-15.966, and P = 0.04.Our results suggested that genetic variants in the TNF gene may influence acute injury in rectal cancer patients treated with chemoradiotherapy and may be a predictor for personalized treatment. Additional larger and independent studies are needed to confirm our findings.