The isolation of ecdysterone inducible genes by hybridization subtraction chromatography.

We have developed a procedure for selectively enriching a mRNA population for inducible sequences. Other than the induced mRNA species, the population of mRNA in control cells is approximately the same as the mRNA population in induced cells. Cytoplasmic mRNA from control cells is bound to oligo (dT)-cellulose and used as a template for reverse transcriptase, the oligo (dT) serving as a primer. After removing the template mRNAs, the cDNA-cellulose column is used to hybridize a population of mRNAs from induced cells. The non-hybridized poly A+ RNAs are greatly enriched in the inducible sequences. We have used this technique of hybridization subtraction chromatography to select a mRNA population enriched for the mRNAs inducible by ecdysterone in Schneider's Line 2 Drosophila cells. This population of RNAs was used to screen a recombinant library. Preliminary results indicate that approximately 10% of the RNA in the probe population represents ecdysterone inducible sequences. Methods are described for optimizing the cDNA synthesis reaction (we obtain greater than or equal to 30% efficiency) and hybridizing RNA to the cDNA-cellulose resin. This method can be used to select induced mRNAs regardless of the way in which the induction is brought about

Vesicular monoamine transporter protein expression correlates with clinical features, tumor biology, and MIBG avidity in neuroblastoma: a report from the Children’s Oncology Group

PURPOSE: Vesicular monoamine transporters 1 and 2 (VMAT1 and VMAT2) are thought to mediate MIBG uptake in adult neuroendocrine tumors. In neuroblastoma, the norepinephrine transporter (NET) has been investigated as the principal MIBG uptake protein, though some tumors without NET expression concentrate MIBG. We investigated VMAT expression in neuroblastoma and correlated expression with MIBG uptake and clinical features. METHODS: We evaluated VMAT1 and VMAT2 expression by immunohistochemistry (IHC) in neuroblastoma tumors from 76 patients with high-risk metastatic disease treated on a uniform cooperative group trial (COG A3973). All patients had baseline MIBG diagnostic scans centrally reviewed. IHC results were scored as the product of intensity grading (0-3+) and percent of tumor cells expressing the protein of interest. Association of VMAT1 and VMAT2 scores with clinical and biological features was tested using Wilcoxon rank-sum tests. RESULTS: Patient characteristics were typical of high-risk neuroblastoma, though the cohort was intentionally enriched for patients with MIBG non-avid tumors (n=20). VMAT1 and VMAT2 were expressed in 62% and 75% of neuroblastoma tumors, respectively. VMAT1 and VMAT2 scores were both significantly lower in MYCN amplified tumors and in tumors with high mitotic karyorrhectic index. MIBG avid tumors had significantly higher VMAT2 scores compared to MIBG non-avid tumors (median 216 vs. 45; p = 0.04). VMAT1 expression did not correlate with MIBG avidity. CONCLUSIONS: VMAT1 and VMAT2 are expressed in the majority of neuroblastomas. Expression correlates with other biological features. Expression level of VMAT2 but not VMAT1 correlates with avidity for MIBG