No abstract

SUMMARYThe ability of the cell cycle inhibitor n-butyrate to induce T helper 1 (Th1) cell anergy is dependent upon its ability to block the cell cycle progression of activated Th1 cells in G1.Results reported here show that although both interleukin (IL)-2 and antigen (Ag) push Th1 cells into G1 where they are blocked by n-butyrate, only the Ag-activated Th1 cells demonstrate functional anergy once the n-butyrate has been removed from the culture.

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The RNA sequencing (RNA-Seq) technique is now routinely used to quantitatively explore genome-wide expression by various research fields including cancer research. The most common RNA-seq methodology produce billions of short-read sequencing in the range of 100–600 base pairs, from which it is occasionally difficult to reconstruct isoform-level transcriptome and fusion genes. The limitations of the short-reads can be overcome by using third-generation sequencing technologies, such as Oxford Nanopore Technologies (ONT). This study aims to perform full-length cDNA sequencing using ONT platform and investigate the abilities of ONT in (1) identifying differential gene expression, (2) detecting differential transcript isoform usage, and (3) detecting fusion genes. To do these methods, CNS-1 cells were implanted into the frontal lobes of three Lewis rats. The CNS-1 model is a histocompatible astrocytoma cell line with an invasive pattern mimicking glioblastoma (GBM). After two weeks of transplantation, the transplanted tumors and the normal brain on the other side were collected as matched normal-tumor pairs. Total RNA extracted from the samples were subjected to the full-length cDNA sequencing on a portable MinION sequencer. In tumors samples, 615 genes involved in cell cycle were upregulated, whereas 1067 genes involved in neurological functions were downregulated. Finally, we could identify differential transcript isoform expression and fusion genes from the matched normal-tumor pairs. Overall, full-length sequencing of the cDNA molecules permitted a detailed characterization of the differential gene expression, the isoform complexity, and fusion genes. In the near future, we will use these methods on human samples.

Molecular classification of diffuse glioma enables more-precise diagnosis, prognosis, and treatment decisions. Currently, combination of two molecular markers, isocitrate dehydrogenase 1 and 2 (IDH1/ IDH2) gene mutation information and O6-Methylguanine-DNA-methyltranferase (MGMT) methylation status, are the main prognostic biomarkers of newly diagnosed diffuse gliomas. Furthermore, an accurate interpretation of MGMT-promoter methylation status is essential to determining which patients benefit from temozolomide (TMZ) therapy. The presence of an IDH mutation can be easily tested by PCR or next generation sequencing. However, there remains controversy with the identification of MGMT-promoter methylation status since there exists variable degrees of methylation and no clear consensus on cutoff values for “methylated” or “unmethylated” have been defined. To be best suited for routine clinical setting and research use, the optimal test should be reproducible, readily available, and timely. Therefore, we explored the feasibility of single-molecule nanopore third generation sequencing technology to comprehensively assess both mutation and methylation status simultaneously. This technology allows methylation detection directly from the native DNA sequence without requiring bisulfite treatment which reduces processing time. To specifically study IDH1, IDH2, and MGMT-promoter loci, we combined the CRISPR-Cas9 system to cut desired DNA fragments in a non–amplification dependent fashion. In addition, a data analysis pipeline was developed to quantitatively detect methylation. We applied our approach on human DNA controls, glioma cell lines and 4 patient brain tumor samples and were enabled to assess mutation and methylation status of targeted loci within 1.5 days. The promise of CRISPR-Cas9-targeted nanopore sequencing in accelerating and improving the molecular diagnostics of diffuse glioma will be illustrated in this meeting. These efforts are in line with improving precision medicine and can be applied to all cancer types.