GTI-2040 displays cooperative anti-tumor activity when combined with interferon alpha against human renal carcinoma xenografts.

GTI-2040, an antisense oligonucleotide targeting the small subunit of ribonucleotide reductase, acts as an anti-tumor agent in animal models of human cancer. In the present study, the anti-tumor activity of GTI-2040, in combination with interferon alpha (IFNalpha) was investigated against human renal cell carcinoma tumors xenografted into mice. The human renal cell carcinoma cell lines, Caki-1 and A498 were sensitive to IFNalpha both in vitro and when implanted into mice. In combination with GTI-2040 there were cooperative effects at intermediate doses of the two agents and complete tumor regression at higher combination doses. A control oligonucleotide was not effective as a monotherapy and did not improve the efficacy of IFNalpha. The effect of combination treatment on apoptosis and proliferation of tumor cells, isolated from xenografted tumors, was examined by histochemistry. GTI-2040 increased the percentage of cells undergoing apoptosis with a concomitant decrease in proliferation. IFNalpha alone had no effect but in combination with GTI-2040 resulted in increased apoptosis and decreased proliferation compared to GTI-2040 alone. Taken together these results expand the potential clinical applications of GTI-2040 to include combination therapy with IFNalpha.

Optimization of the PAXgene blood RNA extraction system for gene expression analysis of clinical samples.

One major problem associated with collecting whole blood from patients for use as a source of RNA in gene expression studies is that the RNA degrades during collection and storage. Preservation of RNA quality is vital in such studies because the stability of the RNA ultimately affects analysis of gene expression. In this study the PAXgene blood collection system was compared with a standard erythrocyte lysis method for isolating RNA from blood samples. The methods were compared in terms of RNA yield, RNA stabilization, and DNA contamination. The study also included the downstream application to RT-PCR analysis for relative mRNA expression levels of the ribonucleotide reductase subunits R1 and R2. The results show that blood collection in conventional collection tubes, and leukocyte isolation by erythrocyte lysis lead to significant degradation of RNA. Our findings confirm the ability of PAXgene to stabilize RNA in whole blood; however, RNA extracted by the PAXgene method contained significant DNA contamination. Given the low basal expression of the target genes analyzed in this study, contaminating DNA could potentially affect accurate interpretation of RT-PCR data. As a result, the PAXgene protocol was optimized to include off-column DNase treatments, which yielded high-quality RNA suitable for gene expression studies. Furthermore, the results suggest that RNA isolation with PAXgene is advantageous compared to traditional extraction methods for RT-PCR analysis of large or different-sized amplicons.