Table 1.
ALK translocation status in 3 IHC-positive cases.
Fig 1.
ALK fusion in colorectal cancer (Case one).
A-B, Immunohistochemistry showed cytoplasmic immunoreactivity for ALK protein expression (A, 20×; B, 200×). C, No immunoreactivity was found in normal tissue (200×). D, fluorescence in situ hybridization (FISH) performed with Vysis LSI ALK Dual color Break-Apart FISH probes detected ALK fusion as split red and green signals (arrows) (1000×).
Fig 2.
ALK fusion in colorectal cancer (Case two).
A-B, Immunohistochemistry showed cytoplasmic immunoreactivity for ALK protein expression (A, 20×; B, 200×). C, fluorescence in situ hybridization (FISH) performed with Vysis LSI ALK Dual color Break-Apart FISH probes detected ALK fusion as split red and green signals (arrows) (1000×). D, Real-time PCR detection of EML4-ALK fusions. Graph from the real-time PCR showed change in the normalized reporter signal (delta Rn) against PCR cycle number. The grey curve stands for internal control and the blue curve stands for the EML4-ALK fusion.
Fig 3.
ALK fusion in gastric cancer (Case three).
A, Immunohistochemistry showed cytoplasmic immunoreactivity for ALK protein expression in a proportion of cancer cells (20×). B-C, ALK protein was only expressed in tumor cells with neuroendocrine differentiation, but not expressed in gastric adenocarcinoma cells, indicating intratumoral heterogeneity (A, 20×; B, 200×). D, fluorescence in situ hybridization (FISH) performed with Vysis LSI ALK Dual color Break-Apart FISH probes showed FISH-negative result as intact fused signals. (1000×).
Fig 4.
A novel fusion gene SPTBN1-ALK.
A, Targeted sequencing analysis revealed a novel fusion gene SPTBN1-ALK which created by invertion between two breakpoints in the intron 7 of SPTBN1 gene and the intron 19 of ALK gene. Sanger sequencing of reverse transcription-PCR product confirmed the fusion of SPTBN1-ALK gene, as showed in the lower panel. B, Functional domain analysis of SPTBN1, ALK, and SPTBN1–ALK fusion protein sequences. ALK, anaplastic lymphoma kinase; SPTBN1, spectrin, beta, non-erythrocytic 1; CH, calponin homology domain; PH, pleckstrin homology domain; TM, transmembrane domain.