ABSTRACT
Previous work has shown that hepatic levels of human glutathione transferase zeta 1 (GSTZ1) protein, involved in tyrosine catabolism and responsible for metabolism of the investigational drug dichloroacetate, increase in cytosol after birth before reaching a plateau around age 7. However, the mechanism regulating this change of expression is still unknown, and previous studies showed that GSTZ1 mRNA levels did not correlate with GSTZ1 protein expression. In this study, we addressed the hypothesis that microRNAs (miRNAs) could regulate expression of GSTZ1. We obtained liver samples from donors aged less than 1 year or older than 13 years and isolated total RNA for use in a microarray to identify miRNAs that were downregulated in the livers of adults compared with children. From a total of 2578 human miRNAs tested, 63 miRNAs were more than 2-fold down-regulated in adults, of which miR-376c-3p was predicted to bind to the 3' untranslated region of GSTZ1 mRNA. There was an inverse correlation of miR-376c-3p and GSTZ1 protein expression in the liver samples. Using cell culture, we confirmed that miR-376c-3p could downregulate GSTZ1 protein expression. Our findings suggest that miR-376c-3p prevents production of GSTZ1 through inhibition of translation. These experiments further our understanding of GSTZ1 regulation. Furthermore, our array results provide a database resource for future studies on mechanisms regulating human hepatic developmental expression. SIGNIFICANCE STATEMENT: Hepatic glutathione transferase zeta 1 (GSTZ1) is responsible for metabolism of the tyrosine catabolite maleylacetoacetate as well as the investigational drug dichloroacetate. Through examination of microRNA (miRNA) expression in liver from infants and adults and studies in cells, we showed that expression of GSTZ1 is controlled by miRNA. This finding has application to the dosing regimen of the drug dichloroacetate. The miRNA expression profiles are provided and will prove useful for future studies of drug-metabolizing enzymes in infants and adults.
Subject(s)
Aging/genetics , Down-Regulation , Gene Expression Regulation, Developmental , Glutathione Transferase/genetics , MicroRNAs/metabolism , 3' Untranslated Regions/genetics , Adolescent , Adult , Aged , Aged, 80 and over , Aging/metabolism , Female , Gene Expression Profiling , Glutathione Transferase/metabolism , HEK293 Cells , Hep G2 Cells , Hepatobiliary Elimination/genetics , Humans , Infant , Infant, Newborn , Liver/enzymology , Liver/growth & development , Male , Middle Aged , RNA, Messenger/analysis , RNA, Messenger/metabolism , Young AdultABSTRACT
Purpose. This study seeks to evaluate the natural history, outcome, and possible prognostic factors in patients with brain metastases derived from gastrointestinal cancers. Methods. The clinical features, prognostic factors, and the effects of different treatment modalities on survival were retrospectively investigated in 103 patients with brain metastases derived from gastrointestinal cancers. Results. The median time from diagnosis of primary tumor to brain metastasis was 22.00 months. The interval between diagnosis of primary tumor relapse and brain metastasis was 8.00 months. The median follow-up time was 7.80 months. The median survival time after diagnosis of brain metastases was 4.10 months for all patients and 1.17 months for patients who received only steroids (36.9 %), 3.97 months for patients who only received whole-brain radiation therapy (WBRT 31.1 %), 11.07 months for patients who received gamma-knife surgery alone or/and WBRT (20.4 %), and 13.70 months for patients who underwent surgery and radiotherapy (12 patients, 11.6 %) (P < 0.001). Multivariate analysis revealed that recursive partitioning analysis (RPA) class, extracranial metastasis, and chemotherapy were independent prognostic factors. Brain metastasis derived from gastrointestinal tract cancer is rare, and overall patient survival is poor. Conclusion. RPA class, chemotherapy after brain metastases, and treatment regimens were independent prognostic factors for the survival of patients with brain metastases derived from gastrointestinal cancers (AU)
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