Knockout of phospholipase Cε attenuates N-butyl-N-(4-hydroxybutyl) nitrosamine-induced bladder tumorigenesis

Bladder cancer frequently shows mutational activation of the oncogene Ras, which is associated with bladder carcinogenesis. However, the signaling pathway downstream of Ras remains to be fully elucidated. N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) is able to induce bladder cancer by driving the clonal expansion of initiated cells carrying the activated form of Ras. Phospholipase Cε (PLCε) is the main target of BBN, while the tumor promoting role of PLCε remains controversial. The present study examined the role of PLCε in BBN-induced bladder carcinogenesis of mice with genetically inactivated PLCε. Using light and electron microscopy, the present study demonstrated that PLCε(−/−) mice were resistant to BBN-induced bladder carcinogenesis. Furthermore, it was demonstrated that cyclooxygenase 2 and vascular endothelial growth factor-A were affected by the PLCε background of the mice, suggesting that the role of PLCε in tumor promotion may be ascribed to augmentation of inflammatory responses and angiogenesis. These results indicated that PLCε is crucial for BBN-induced bladder carcinogenesis as well as signaling downstream of Ras, and that PLCε is a candidate molecular target for the development of anti-cancer drugs.