Transcriptome Sequencing of Tumor-educated Lung Epithelial Cells in the Pre-metastatic Niche

We performed transcriptome sequencing on epithelial cells, isolated from lungs of normal and tumor-bearing mice, to shed light on the function and phenotype changes of lung epithelial cells in the pre-metastatic niche. Overall design: Lung tissues from tumor-bearing mouse and normal mouse (as a control) were digested into single-cell suspensions and CD45- SftpC+ epithelial cells were purified by FACS, followed by transcriptome sequencing. All procedures were performed according to the standard manufacturer's protocol. The total RNA samples are first treated with DNase I to degrade any possible DNA contamination. Then the mRNA is enriched by using the oligo(dT) magnetic beads (for eukaryotes). Mixed with the fragmentation buffer, the mRNA is fragmented into short fragments (about 200 bp). Then the first strand of cDNA is synthesized by using random hexamer-primer. Buffer, dNTPs, RNase H and DNA polymerase I are added to synthesize the second strand. The double strand cDNA is purified with magnetic beads. End reparation and 3'-end single nucleotide A (adenine) addition is then performed. Finally, sequencing adaptors are ligated to the fragments. The fragments are enriched by PCR amplification. During the QC step, Agilent 2100 Bioanaylzer and ABI StepOnePlus Real-Time PCR System are used to qualify and quantify of the sample library. The library products are ready for sequencing via Illumina HiSeqTM 2000 or other sequencer when necessary.