Lei Xu

All Publications

• Genomic analysis of fibrolamellar hepatocellular carcinoma. Human molecular genetics Xu, L., Hazard, F. K., Zmoos, A., Jahchan, N., Chaib, H., Garfin, P. M., Rangaswami, A., Snyder, M. P., Sage, J. 2015; 24 (1): 50-63

  Abstract

  Pediatric tumors are relatively infrequent but are often associated with significant lethality and lifelong morbidity. A major goal of pediatric cancer research has been to identify key drivers of tumorigenesis to eventually develop targeted therapies to enhance cure rate and minimize acute and long-term toxic effects. Here we used genomics approaches to identify biomarkers and candidate drivers for fibrolamellar hepatocellular carcinoma (FL-HCC), a very rare subtype of pediatric liver cancer for which limited therapeutic options exist. In-depth genomics analyses of one tumor followed by immunohistochemistry validation on seven other tumors showed expression of neuroendocrine markers in FL-HCC. DNA and RNA sequencing data further showed that common cancer pathways are not visibly altered in FL-HCC but identified two novel structural variants, both resulting in fusion transcripts. The first, a 400kb deletion, results in a DNAJ1-PRKCA fusion transcript, which leads to increased PKA activity in the index tumor case and other FL-HCC cases compared to normal liver. This PKA fusion protein is oncogenic in HCC cells. The second gene fusion event, a translocation between the CLPTML1 and GLIS3 genes, generates a transcript whose product also promotes cancer phenotypes in HCC cell lines. These experiments further highlight the tumorigenic role of gene fusions in the etiology of pediatric solid tumors and identify both candidate biomarkers and possible therapeutic targets for this lethal pediatric disease.

  View details for DOI 10.1093/hmg/ddu418

  View details for PubMedID 25122662

• Metabolic alterations in yeast lacking copper-zinc superoxide dismutase FREE RADICAL BIOLOGY AND MEDICINE Sehati, S., Clement, M. H., Martins, J., Xu, L., Longo, V. D., Valentine, J. S., Gralla, E. B. 2011; 50 (11): 1591-1598

  Abstract

  Yeast lacking copper-zinc superoxide dismutase (sod1?) have a number of oxygen-dependent defects, including auxotrophies for lysine and methionine and sensitivity to oxygen. Here we report additional defects in metabolic regulation. Under standard growth conditions with glucose as the carbon source, yeast undergo glucose repression in which mitochondrial respiration is deemphasized, energy is mainly derived from glycolysis, and ethanol is produced. When glucose is depleted, the diauxic shift is activated, in which mitochondrial respiration is reemphasized and stress resistance increases. We find that both of these programs are adversely affected by the lack of Sod1p. Key events in the diauxic shift do not occur and sod1? cells do not utilize ethanol and stop growing. The ability to shift to growth on ethanol is gradually lost as time in culture increases. In early stages of culture, sod1? cells consume more oxygen and have more mitochondrial mass than wild-type cells, indicating that glucose repression is not fully activated. These changes are at least partially dependent on the activity of the Hap2,3,4,5 complex, as indicated by CYC1-lacZ reporter assays. These changes may indicate a role for superoxide in metabolic signaling and regulation and/or a role for glucose derepression in defense against oxidative stress.

  View details for DOI 10.1016/j.freeradbiomed.2011.03.004

  View details for Web of Science ID 000290603700015

  View details for PubMedID 21397007