Aspects of the YBX1-dependent mechanism of drug resistance in hepatocellular carcinoma

Background: Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer. In the Rio Grande Valley (RGV), high rates of obesity, diabetes, and MAFLD elevate HCC incidence, further worsened by socioeconomic disparities and limited healthcare access. Consequently, late-stage diagnoses and therapeutic resistance lead to poor patient outcomes, emphasizing the importance of understanding the molecular mechanisms behind HCC progression. Y-box binding protein 1 (YBX1) is a multifunctional regulator of transcription and translation involved in EMT, metastasis, and drug resistance in various cancers, including HCC. To investigate the downstream signaling pathways activated by YBX1 overexpression (OE), we developed puromycin-stable GFP-tagged YBX1 OE SK-HEP1 cell lines. These cell lines have been evaluated for their invasion, migration, proliferation, colony formation, and cell impedance properties. YBX1 OE influenced multiple downstream kinases. We identified a specific kinase responsible for oncogenicity and drug resistance. We will continue to characterize and validate the kinase activity using specific activators and inhibitors. Methods: The TCGA was analyzed for the YBX1 profile in the human HCC cohort. SK-HEP1 cells were used to develop a puromycin-stable YBX1 OE cell line using lentiviral plasmids. The cell lines were also enriched for GFP expression. Functional assays included cell proliferation, colony formation, migration, invasion, and real-time impedance analysis using the xCELLigence system. MTT assays determined IC50 values. The Human Proteome Profiler Array was used for kinase array analysis. Kinase activator and inhibitor assays were also performed. Results: Analysis of the TCGA revealed elevated YBX1 expression in HCC tumors compared to normal tissues, which correlates with poor survival and increased metastasis. In vitro, YBX1 overexpression boosted proliferation, migration, invasion, and colony formation, while knockdown diminished these effects. xCELLigence analysis confirmed faster growth kinetics in cells overexpressing YBX1. Phosphoproteomic profiling identified several YBX1-regulated kinases, including members of the Src family. Conclusion: Stable SK-HEP1 models with differential YBX1 expression have been successfully established and characterized. These findings confirm YBX1's oncogenic role in HCC. Ongoing research involving kinase pathway inhibitors and activators may uncover new therapeutic targets to overcome resistance and enhance outcomes for HCC patients in the RGV and beyond.