[Alternative Splicing Detection as Biomarker Candidates for Cancer Diagnosis and Treatment with Establishment of Clinical Biobank in Chiba University].

Alternative splicing is a fundamental process of gene regulation that contributes to protein diversity, a common phenomenon in the mammalian genome. Alternative splicing events not only happen in the normal gene regulation process, but are also closely related to certain diseases, including cancer. In this review, we briefly demonstrate the proof of concept (POC) of the relationship between alternative splicing and DNA damage, and describe the associations among alternative splicing and cancer pathogenesis, DNA damage, and gastrointestinal cancers. We discuss whether alternative splicing leads to genetic instability, which is considered to be a driving force for tumorigenesis. FUSE-binding protein (FBP) -interacting repressor (FIR) is a c-myc transcriptional suppressor. A splice variant of FIR that lacks exon 2 in the transcriptional repressor domain (FIRΔexon2), upregulates c-myc transcription by inactivating wild-type FIR. FIR+/- mice exhibited marked c-myc mRNA upregulation, particularly in the peripheral blood (PB), without any significant pathogenic phenotype. Because the single knockout of TP53 generates thymic lymphoma, FIR+/-TP53-/- mice developed T-cell type acute lymphocytic/lymphoblastic leukemia (T-ALL) with increased organ or bone marrow invasion and showed a poor prognosis. After describing the POC of alternative splicing of FIR in DNA damage and carcinogenesis, clinical application for cancer diagnosis and treatment by FIR/FIRΔexon2 was briefly summarized. Chiba University has prepared a biobank to support studies to develop biomarker detection, molecular diagnosis, and "Omics" research. In conclusion, alternative splicing of FIR, generating FIRΔexon2, potentially contributes to not only colorectal carcinogenesis, but also leukemogenesis, and a better understanding of the role and mechanism of alternative splicing in tumorigenesis may reveal new directions for cancer biomarker detection.