Downregulation of the keratins CK13 and CK14 does not significantly affect cell viability of human urinary bladder carcinoma cells

Introduction:
Bladder cancer is the ninth most common tumour entity worldwide. Aberrant expression of different keratins has been described in bladder cancer, which is used for diagnostic purposes, but it can also have prognostic value. However, not all keratins have been analysed in bladder cancer, and whether keratins are important for cell viability of bladder cancer tumour cells is not yet known.

Material and methods:
We analyse the expression of CK10, CK13, and CK14 in 4 different urinary bladder transitional cell carcinoma cell lines via western blot. Furthermore, we downregulate the expression of CK13 and CK14 using siRNAs and evaluate the cell viability of the carcinoma cells.

Results:
In this study, we show that different urinary bladder transitional cell carcinoma cell lines have distinct expression pattern of the keratins CK10, CK13, and CK14. Using several siRNAs targeting either CK13 or CK14, we show that both keratins have long protein half-lives. Although we achieve a reduction in CK13 and CK14 protein levels, these reductions do not influence the cell viability of the cell lines.

Conclusions:
In conclusion, we provide evidence that CK10, CK13, and CK14 are expressed on the protein level in different urinary bladder transitional cell carcinoma cell lines, but that their targeting does not affect the viability of the carcinoma cells.