Determination of the complexity and diversity of the TCR β-chain CDR3 repertoire in bladder cancer using high-throughput sequencing

The present study aimed to investigate the complexity and diversity of the T lymphocyte immune repertoire in patients with bladder cancer. To do so, the immune state of patients was assessed. The study also aimed to elucidate the aetiology and pathogenesis of bladder cancer to provide a novel theoretical basis for disease prevention, diagnosis, treatment and prognosis monitoring. Cancerous and paracancerous (control) tissue samples were collected from five patients diagnosed with muscle-invasive bladder cancer. Multiplex polymerase chain reaction and Illumina high-throughput sequencing were used to determine the characteristics and clonal diversity of the T-cell receptor (TCR) β-chain complementarity-determining region 3 (CDR3) gene in the cancerous and paracancerous tissues of patients with bladder cancer. The degree of clonal expansion in malignant samples was significantly higher than in adjacent samples. Furthermore, ΤCRβ variable (TRBV), ΤCRβ diversity (TRBD) and ΤCRβ joining (TRBJ) repertoires were significantly different in cancerous samples compared with adjacent samples. In addition, 13 identified V-J pairs were highly expressed in cancerous samples whereas they had low expression in control samples. In conclusion, the degree of T-cell clonal expansion in bladder cancerous tissue was higher than in paracancerous tissue, whereas the immune diversity of the tissues of patients with bladder cancer was significantly lower. The DNA sequence and amino acid sequences, and V-J combination level may be used to comprehensively understand the diversity and characteristics of TCR CDR3 in bladder cancer and paracancerous tissues, and to evaluate the immune status of bladder cancer to develop therapeutic targets and biomarkers for prognosis monitoring.