Relationship of Cell Proliferating Marker Expressions with PGE2 Receptors in Regenerating Rat Renal Tubules after Cisplatin Injection

Cisplatin, an anticancer drug, is well known to have nephrotoxicity as an adverse effect. We investigated the expressions of cell cycle markers and prostaglandin E2 (PGE2) receptors (EP) in the affected renal tubules in rats injected with a single dose (6 mg/kg body weight) of cisplatin. On days 1-3 after dosing, the affected renal epithelial cells were almost desquamated, showing necrosis. On day 5 onwards, the renal tubules were rimmed by flattened or cuboidal epithelial cells with basophilic cytoplasm; BrdU-immunopositive cells began to significantly increase, indicating regeneration. Simultaneously, TUNEL-positive apoptotic cells were also seen. On days 1-5, cyclin D1-immunopositive cells were decreased with an increased expression in p21 mRNA, indicating G1 arrest in the cell cycle. The affected renal epithelial cells began to react to EP4 receptor, but not to EP2 receptor. Some EP4 receptor-reacting epithelial cells gave a positive reaction to BrdU or cyclin D1. Collectively, the affected renal tubules underwent various alterations such as necrosis, apoptosis, regeneration and G1 arrest; the aspects might be influenced by endogenous PGE2 through EP4 receptor.