ABSTRACT: (R,R’)-4-methoxy-1-naphthylfenoterol (MNF) inhibits in vitro proliferation of several types of cancer cell lines. In this study, the in vivo antitumor effects of MNF were evaluated using rat C6 glioma cells implanted subcutaneously into the lower flank of 5 week-old NMRI/Nude female Swiss mice. Three days after the inoculation, the mice were subjected to intraperitoneal injections of saline or MNF (2mg/kg) for five days per week for16 days. Tumor volumes were measured everyday using slide calipers. Significant reductions in mean tumor volumes were observed in mice receiving MNF when compared with the saline-treated group (p<0.001, n=17-19). At the end of the study, animals were sacrificed and tumors were collected for cDNA microarray, quantitative RT-PCR and immunoblot analyses. Significant decrease in expression of genes involved in cellular proliferation, including mitotic checkpoint kinase MAD3L (Bub1b), cyclin-dependent kinase inhibitor 3 (Cdkn3) and cyclin A2 (Ccna2), as well as molecular markers for glioblastoma, such as oligodendrocyte transcription factor 1 (Olig1) and SRY-box 4 (Sox4) was observed in tumors of MNF-treated mice as compared to saline-injected controls. The efficacy of MNF against C6 glioma cancer in vivo was accompanied by marked reduction in the expression of cell cycle regulator proteins, including cyclin A and cyclin D1, in tumor extracts. This study is the first demonstration of MNF-dependent chemoprevention in a glioblastoma xenograft model in the mouse and may offer a potential mechanism for its anticancer action in vivo. Keywords: fenoterol derivative; C6 glioma; tumor xenografts; microarray analysis; Total RNA was isolated from rat C6 glioma xenografts harvested from vehicle and MNF-treated nude mice (n = 3 per group, cohort 1). This analysis was repeated in a second cohort of animals (n = 3 per group, cohort 2). Total cellular RNA was extracted using an RNeasy plus mini kit (QIAGEN, Valencia, CA), and its quality was assessed using an Agilent BioAnalyzer using RNA 6000 Nano Chips (Agilent Technologies, Santa Clara, CA). Transcriptional profiling was determined using Illumina Sentrix BeadChips (Illumina, San Diego, CA). Total RNA was used to generate biotin-labeled cRNA with the Illumina TotalPrep RNA Amplification Kit. In short, 0.5ug of total RNA was first converted into single-stranded cDNA with reverse transcriptase using an oligo-dT primer containing the T7 RNA polymerase promoter site and then copied to produce double-stranded cDNA molecules. The double-stranded cDNA was cleaned and concentrated with the supplied columns and used in an overnight in-vitro transcription reaction where single-stranded RNA (cRNA) was generated incorporating biotin-16-UTP. A total of 0.75µg of biotin-labeled cRNA was hybridized at 58 °C for 16 h to Illumina's Sentrix Rat Ref-12 Expression BeadChips. The arrays were washed, blocked and the labeled cRNA was detected by staining with streptavidin-Cy3. Hybridized arrays were scanned using an Illumina BeadStation 500X Genetic Analysis Systems scanner and the image data extracted using Illumina’s GenomeStudio software, version 1.6.1. For statistical analysis, the expression data were filtered to include only probes with a consistent signal on each chip and an Illumina detection p value < 0.02.
