Cell cycle arrest in a model of colistin nephrotoxicity
Authors: Eadon, Michael T.; Hack, Bradley K.; Alexander, Jessy J.; Xu, Chang; Dolan, M. Eileen; Cunningham, Patrick N.
Colistin (polymixin E) is an antibiotic prescribed with resurging frequency for multidrug resistant gram negative bacterial infections. It is associated with nephrotoxicity in humans in up to 55% of cases. Little is known regarding genes involved in colistin nephrotoxicity. A murine model of colistin-mediated kidney injury was developed. C57/BL6 mice were administered saline or colistin at a dose of 16 mg/kg/day in 2 divided intraperitoneal doses and killed after either 3 or 15 days of colistin. After 15 days, mice exposed to colistin had elevated blood urea nitrogen (BUN), creatinine, and pathologic evidence of acute tubular necrosis and apoptosis. After 3 days, mice had neither BUN elevation nor substantial pathologic injury; however, urinary neutrophil gelatinase-associated lipocalin was elevated (P = 0.017). An Illumina gene expression array was performed on kidney RNA harvested 72 h after first colistin dose to identify differentially expressed genes early in drug treatment. Array data revealed 21 differentially expressed genes (false discovery rate < 0.1) between control and colistin-exposed mice, including LGALS3 and CCNB1. The gene signature was significantly enriched for genes involved in cell cycle proliferation. RT-PCR, immunoblot, and immunostaining validated the relevance of key genes and proteins. This murine model offers insights into the potential mechanism of colistin-mediated nephrotoxicity. Further studies will determine whether the identified genes play a causative or protective role in colistin-induced nephrotoxicity.
Integrated bioinformatics analysis reveals that the expression of cathepsin S is associated with lymph node metastasis and poor prognosis in papillary thyroid cancer
Authors: Tan, Juan; Qian, Xiaoxiao; Song, Bin; An, Xiumin; Cai, Tingting; Zuo, Zhihua; Ding, Dafa; Lu, Yibing; Li, Hong
The prognosis of the majority of patients with papillary thyroid cancer (PTC) is excellent, although there are patients who experience disease recurrence and progression. The aim of the present study was to identify potential prognostic risk markers in PTC. Differentially expressed genes (DEGs), identified from four Genome Expression Omnibus cohorts were subjected to functional enrichment analyses with Gene Ontology terms and the Kyoto Encyclopedia of Genes and Genome pathways. Hub genes, filtered from cytoHubba, were validated using the The Cancer Genome Atlas (TCGA) cohort, and their associations with clinicopathological features and prognosis were analyzed. A total of 277 DEGs were identified following data preprocessing. DEGs were primarily enriched in small cell lung cancer', ECM-receptor interaction', pathways in cancer' and tyrosine metabolism'. Hub genes [APOE, cathepsin S (CTSS), insulin receptor substrate 1 (IRS1), KIT, LGALS3, RUNX2 and TGFBR1] were extracted from cytoHubba. Their expression in the TCGA cohort was consistent with that in the GEO cohorts. CTSS (P=0.006) and IRS1 (P=0.005) were associated with disease-free survival, as determined using the Kaplan-Meier analysis. CTSS was an independent risk factor for poor disease-free survival (HR, 2.649; 95% CI, 1.095-6.409; P=0.031). Patients with high expression of CTSS exhibited different histological types (increased tall-cell subtype and reduced follicular subtype; P<0.001), more frequent lymph node metastasis (P<0.001) and advanced tumor-node-metastasis stages (P=0.049) compared with the low-expression group. High expression of CTSS was independently associated with lymph node metastasis (OR, 2.015; 95% CI, 1.225-3.315; P=0.006). Therefore, CTSS may serve as a predictive risk marker for the progression and prognosis of PTC.