Faculty Bibliography

Repair of DNA strand breaks induced during lymphoid antigen receptor rearrangement involves non-homologous end-joining (NHEJ). We investigated NHEJ in the aetiology of lymphoproliferative disorders (LPDs) and the disease subtypes therein through real-time quantitative RT-PCR gene expression analysis. Lower expression of XRCC6 and MRE11A was observed in all tumours, with higher expression of both XRCC4 and RAD50 observed only in multiple myeloma (MM). Hierarchical clustering enabled tumours to be clearly distinguished from controls, and by morphological sub-type. We postulate this identifies targets worthy of investigation in the genetic predisposition, pathogenesis and prognosis of lymphoid malignancies.

PURPOSE/OBJECTIVE:Myeloma is a clonal malignancy of plasma cells. Poor-prognosis risk is currently identified by clinical and cytogenetic features. However, these indicators do not capture all prognostic information. Gene expression analysis can be used to identify poor-prognosis patients and this can be improved by combination with information about DNA-level changes. EXPERIMENTAL DESIGN/METHODS:Using single nucleotide polymorphism-based gene mapping in combination with global gene expression analysis, we have identified homozygous deletions in genes and networks that are relevant to myeloma pathogenesis and outcome. RESULTS:We identified 170 genes with homozygous deletions and corresponding loss of expression. Deletion within the "cell death" network was overrepresented and cases with these deletions had impaired overall survival. From further analysis of these events, we have generated an expression-based signature associated with shorter survival in 258 patients and confirmed this signature in data from two independent groups totaling 800 patients. We defined a gene expression signature of 97 cell death genes that reflects prognosis and confirmed this in two independent data sets. CONCLUSIONS:We developed a simple 6-gene expression signature from the 97-gene signature that can be used to identify poor-prognosis myeloma in the clinical environment. This signature could form the basis of future trials aimed at improving the outcome of poor-prognosis myeloma.

RNA interference (RNAi), a valuable tool to specifically silence gene expression, is becoming an indispensable weapon in the arsenal of functional genomics, target validation and gene-specific therapeutic research. We have shown that Streptolysin-O (SLO) reversible permeabilization is an efficient method to deliver small interfering RNAs (siRNAs) to hard-to-transfect human myeloma cell lines. In addition, we have shown that transfection of siRNAs, using the SLO reversible permeabilization, specifically and efficiently induces gene silencing in myeloma cell lines.