The FN1-ITGB4 Axis Drives Acquired Chemoresistance in Bladder Cancer by Activating FAK Signaling.
While cisplatin-based chemotherapy is pivotal for advanced bladder cancer, acquired resistance remains a major obstacle. This study investigates key molecular drivers of this resistance and potential reversal strategies.
We established GC (Gemcitabine and Cisplatin)-resistant T24-R and UC3-R cell lines from T24 and UM-UC-3 (UC3) cells. Transcriptomic and proteomic analyses identified differentially expressed molecules. Apoptosis and cell viability were assessed by flow cytometry and CCK-8 (Cell Counting Kit-8) assays, while RT-qPCR (Reverse Transcription Quantitative Polymerase Chain Reaction) and Western blot analyzed gene and protein expression. Immunofluorescence evaluated FAK (Focal Adhesion Kinase) phosphorylation, and a xenograft mouse model validated the findings in vivo.
Integrated transcriptomic and proteomic analysis identified FN1 (fibronectin) as a consistently upregulated top candidate in resistant cells (T24-R transcript log2FC = 2.8, protein log2FC = 0.9; UC3-R transcript log2FC = 3.7; all p < 0.001). Knockdown of FN1 reduced chemoresistance (Resistance Index: 5.2 in T24-R and 2.0 in UC3-R cells, p < 0.001) and enhanced apoptosis (approximately 4.5-fold in T24-R and 7.5-fold in UC3-R, p < 0.001). ITGB4 (Integrin Subunit Beta 4) was upregulated in resistant cells (transcript log2FC: 4.2 in T24-R and 3.03 in UC3-R; protein log2FC: 0.67 in T24-R; all p < 0.01). Critically, ITGB4 knockdown abolished the chemoresistance promoted by exogenous FN1, which was associated with increased FAK (Y397) phosphorylation.
Our results demonstrate that the FN1-ITGB4 axis drives chemoresistance in bladder cancer via FAK signaling. Targeting this axis represents a promising strategy to overcome chemoresistance.
We established GC (Gemcitabine and Cisplatin)-resistant T24-R and UC3-R cell lines from T24 and UM-UC-3 (UC3) cells. Transcriptomic and proteomic analyses identified differentially expressed molecules. Apoptosis and cell viability were assessed by flow cytometry and CCK-8 (Cell Counting Kit-8) assays, while RT-qPCR (Reverse Transcription Quantitative Polymerase Chain Reaction) and Western blot analyzed gene and protein expression. Immunofluorescence evaluated FAK (Focal Adhesion Kinase) phosphorylation, and a xenograft mouse model validated the findings in vivo.
Integrated transcriptomic and proteomic analysis identified FN1 (fibronectin) as a consistently upregulated top candidate in resistant cells (T24-R transcript log2FC = 2.8, protein log2FC = 0.9; UC3-R transcript log2FC = 3.7; all p < 0.001). Knockdown of FN1 reduced chemoresistance (Resistance Index: 5.2 in T24-R and 2.0 in UC3-R cells, p < 0.001) and enhanced apoptosis (approximately 4.5-fold in T24-R and 7.5-fold in UC3-R, p < 0.001). ITGB4 (Integrin Subunit Beta 4) was upregulated in resistant cells (transcript log2FC: 4.2 in T24-R and 3.03 in UC3-R; protein log2FC: 0.67 in T24-R; all p < 0.01). Critically, ITGB4 knockdown abolished the chemoresistance promoted by exogenous FN1, which was associated with increased FAK (Y397) phosphorylation.
Our results demonstrate that the FN1-ITGB4 axis drives chemoresistance in bladder cancer via FAK signaling. Targeting this axis represents a promising strategy to overcome chemoresistance.
Authors
Zhang Zhang, Zong Zong, Sun Sun, Chen Chen, Zhu Zhu, Tong Tong, Li Li, Zhu Zhu, Qin Qin, Wu Wu, Wang Wang, He He
View on Pubmed