Clinical application of alternative splicing form of c-myc suppressor FUSE-binding protein-interacting repressor for cancer detection and treatment

Development of useful biomarkers is pivotal for prediction of micro-metastasis, recurrence probability and/or prognosis of the patients. Recent studies have revealed that cancer-specific alternative splicing can be valuable for cancer cell detection. Among them, FUSE-binding protein-interacting repressor, FIR, has been reported to repress c-myc transcription and its exon2-spliced variant, FIRDelta(exon)2, is unable to repress c-myc by competing with authentic FIR in vivo and in vitro. Moreover FIRDelta(exon)2 was frequently discovered in human primary colorectal cancers, but not in the adjacent normal tissues, indicating its cancer-related expression. Thus, the expression level of FIRDelta(exon)2 mRNA in the colorectal cancer tissues as tumor marker candidates is examined. Further, to determine the interacting proteins, FIR-flag or FIRDelta(exon)2-flag stably expressing HeLa cells have been established by G418 selection and nuclear proteins were co immunoprecipitated with flag-conjugated magnetic beads. Those co-immunoprecipitated proteins with FIR or FIRDelta(exon)2 are candidates of tumor makers. In addition, substances that interfers FIR mRNA splicing should be anti-cancer drugs. Together, FIR splicing variant, FIRDelta(exon)2 mRNA or proteins and its interacting proteins are applicable for novel screening tumor markers in colorectal cancer detection.