Niamh E. Kieran

Tissue reoxygenation following hypoxia is associated with ischemia‐reperfusion injury (IRI) and may signal the development of ischemic preconditioning, an adaptive state that is protective against subsequent IRI. Here we used microarray RNA analysis of in vivo and in vitro models of IRI to delineate the underlying molecular mechanisms. Microarray analysis of renal tissue after ischemia‐reperfusion revealed a number of highly up‐regulated antioxidant genes including aldehyde dehydrogenases (ALDH1A1 and ALDH1A7), glutathione S‐transferases (GSTM5, GSTA2 and GSTP1), and NAD(P)H quinone oxidoreductase (NQO1). The transcription factor NF‐E2‐related factor‐2 (Nrf2), a master regulator of this antioxidant response, is also elevated in IRI. Further‐more, microarray analysis of renal epithelial cells exposed to hypoxia/reoxygenation identifi Nrf2 to be up‐regulated on reoxygenation. We also reveal a reoxygenation‐specific nuclear accumulation of Nrf2 protein and subsequent activation of a NQO1 promoter reporter construct. Attenuating reactive oxygen species (ROS) in reoxygenation using the antioxidant N‐acetyl cysteine results in inhibition of Nrf‐2 activation. mRNA levels for Nrf2‐dependent genes were detected in human liver biopsy 1 h after transplantation. These results indicate that reoxygenation‐dependent Nrf‐2 activity facilitates ischemic preconditioning through the induction of antioxidant gene expression and that ROS may be critical in signaling this event.—Leonard, M. O., Kieran, N. E., Howell, K., Burne, M. J., Varadarajan, R., Dhakshinamoorthy, S., Porter, A. G., O'Farrelly, C., Rabb, H., Taylor, C. T. Reoxygenation‐specific activation of the antioxidant transcription factor Nrf2 mediates cytoprotective gene expression in ischemia reperfusion injury. FASEB J. 20, E2166–E2176 (2006)

Breast cancer metastasis remains a clinical challenge, even within a single patient across multiple sites of the disease. Genome-wide comparisons of both the DNA and gene expression of primary tumors and metastases in multiple patients could help elucidate the underlying mechanisms that cause breast cancer metastasis. To address this issue, we performed DNA exome and RNA sequencing of matched primary tumors and multiple metastases from 16 patients, totaling 83 distinct specimens. We identified tumor-specific drivers by integrating known protein-protein network information with RNA expression and somatic DNA alterations and found that genetic drivers were predominantly established in the primary tumor and maintained through metastatic spreading. In addition, our analyses revealed that most genetic drivers were DNA copy number changes, the TP53 mutation was a recurrent founding mutation regardless of subtype, and that multiclonal seeding of metastases was frequent and occurred in multiple subtypes. Genetic drivers unique to metastasis were identified as somatic mutations in the estrogen and androgen receptor genes. These results highlight the complexity of metastatic spreading, be it monoclonal or multiclonal, and suggest that most metastatic drivers are established in the primary tumor, despite the substantial heterogeneity seen in the metastases.

The histologic associations and clinical implications of peritubular capillary C4d staining from long-term renal allografts are unknown. We identified 99 renal transplant patients who underwent an allograft biopsy for renal dysfunction at least 10 yr after transplantation, 25 of whom were C4d-positive and 74 of whom were C4d-negative. The average time of the index biopsy from transplantation was 14 yr in both groups. Compared with C4d-negative patients, C4d-positive patients were younger at transplantation (29 +/- 13 versus 38 +/- 12 yr; P < 0.05) and were more likely to have received an allograft from a living donor (65 versus 35%; P < 0.001). C4d-positive patients had more inflammation, were more likely to have transplant glomerulopathy, and had worse graft outcome. The combined presence of C4d positivity, transplant glomerulopathy, and serum creatinine of >2.3 mg/dl at biopsy were very strong predictors of rapid graft loss. C4d alone did not independently predict graft loss. Retrospective staining of historical samples from C4d-positive patients demonstrated C4d deposition in the majority of cases. In summary, these data show that in long-term renal allografts, peritubular capillary staining for C4d occurs in approximately 25% of biopsies, can persist for many years after transplantation, and strongly predicts graft loss when combined with transplant glomerulopathy.