Figure 4.

A chromosomal rearrangement for generating KIF5B-RET fusion in the lung cancer tissue of AK55. (A) Detection of a 10.6-Mb-long inversion event in chromosome 10 from the whole-genome sequencing of the liver metastatic lung cancer. KIF5B is generally expressed with its universal promoter. By the inversion event, this promoter activates global expression of the KIF5B-RET fusion gene. (B) Validation of the KIF5B-RET fusion gene DNA by inversion-specific PCR amplification and electrophoresis. The fusion gene is only detected in the cancer tissues of AK55 (primary lung cancer, liver and bone metastatic lung cancer tissues). The negative control DNA sample was extracted from a healthy Korean individual (AK1) (Kim et al. 2009). (C) Identification of the fusion gene and inversion breakpoint using Sanger sequencing. The inversion breakpoints were located in the introns of KIF5B and RET as predicted. Two bases downstream from the breakpoint (chr10: 42,931,604, hg18), a 1-bp deletion was identified, suggesting error-prone DNA repair mechanisms might contribute to this inversion event after double-strand DNA breaks.