Time-Dependent Effects of Cisplatin on Autophagy Gene Expression in Bladder Cancer Cells.

Background/

Objectives

Bladder cancer treatment is frequently hindered by chemoresistance to agents such as cisplatin, a process in which autophagy is hypothesized to play a cytoprotective role. This study aimed to investigate the time-dependent transcriptional dynamics of autophagy-related genes in response to cisplatin in bladder cancer cell lines to better elucidate the molecular underpinnings of this resistance.

Methods

Two human bladder cancer cell lines, T24 and 5637, were exposed to varying concentrations of cisplatin. Cell viability and half-maximal inhibitory concentration (IC50) values were determined at 24 and 48 h using the MTS assay. Subsequently, the relative mRNA expression levels of key autophagy-related genes (ULK1, BECN1, ATG5, ATG7, LC3B, SQSTM1/p62, LAMP1, and TFEB) were quantitatively analyzed via RT-qPCR at 0, 6, 24, and 48 h intervals.

Results

Cisplatin exerted a dose- and time-dependent cytotoxic effect, with 5637 cells exhibiting significantly greater sensitivity compared to T24 cells. Transcriptional analysis revealed a dynamic, multiphasic modulation of the autophagic pathway: an early-phase upregulation of initiation genes (ULK1, BECN1), a mid-phase increase in autophagosome formation genes (ATG5, ATG7), and a late-phase alteration in lysosomal regulation genes (LAMP1, TFEB). Notably, the more chemoresistant T24 cells mounted a robust and sustained autophagic transcriptional response, whereas the sensitive 5637 cells demonstrated a more limited and transient reaction.

Conclusions

Cisplatin modulates the autophagic pathway at the transcriptional level in a highly dynamic, time-dependent, and cell-line-specific manner. Interpreted alongside established functional evidence in the literature, the sustained autophagic gene expression observed in the resistant cells is consistent with a potential cytoprotective role, warranting further functional validation at the protein level. These findings map the temporal genetic landscape of cisplatin-induced autophagy, providing a theoretical framework for optimizing the timing of autophagy-targeted combination therapies in bladder cancer.