Identification of the clinical value and biological effects of TTN mutation in liver cancer

Liver cancer, a malignant tumor of the digestive system, is a leading cause of cancer‑related mortality globally. Numerous genetic mutations associated with tumorigenesis have been identified, stemming from genomic instability. However, the clinical implications and therapeutic relevance of these mutations remain poorly understood. The present study evaluated the prognostic significance of titin (TTN) mutations in liver cancer by analyzing the mutation landscape of liver cancer tissues from The Cancer Genome Atlas (TCGA) database. The association between TTN mutations and drug susceptibility was subsequently examined using the OncoPredict algorithm and Cell Counting Kit‑8 (CCK‑8) assays. Furthermore, the impact of TTN mutations on hepatoma cell biology both <i>in vivo</i> and <i>in vitro</i> were assessed by reverse transcription‑quantitative PCR, protein stability assays, colony formation assays, tumor spheroid formation assays and subcutaneous tumor transplantation in BALB/c nude mice. Genetic analysis of the TCGA database revealed that TTN mutations are among the most frequent mutations in liver cancer. Patients with TTN mutations exhibited worse prognoses compared with those with the wild‑type allele. The OncoPredict algorithm and CCK‑8 assays revealed that TTN mutations are associated with altered drug sensitivity, particularly to GSK1904529A, nilotinib, 5‑fluorouracil (5‑FU) and sapitinib. Additionally, TTN mutations were shown to enhance TTN protein stability, decrease intracellular ferrous ion levels and significantly decrease liver cancer sensitivity to 5‑FU both <i>in vitro</i> and <i>in vivo</i>. The findings indicated that TTN mutations increase protein stability and lower intracellular ferrous ion levels, thereby suppressing ferroptosis and contributing to resistance to 5‑FU in hepatoma cells. These results suggest that TTN mutations are associated with poor prognosis in liver cancer and could serve as a predictive biomarker for liver cancer progression, prognosis and drug resistance.