Effects of Tannic Acid on Cisplatin-Induced Changes in Poly(ADP-Ribose) Polymer Turnover in Rat Liver and Thymocyte Nuclei

Abstract

Objective: Cisplatin is a powerful antineoplastic drug widely used in the therapy of cancer patients. To attenuate
undesirable side effects of the drug, chemotherapeutic regimens are employed based on the use of antioxidant
supplementation. The goal of the present study is the examination of the impact of cotreatment with cisplatin
and tannic acid (TA) on key members involved in poly(ADP-ribose) polymer (pPARr) turnover in rat liver and
thymocyte nuclei, i.e., poly(ADP-ribose)polymerase 1 (PARP 1) activity, poly(ADP-ribose)glycohydrolase
(PARG), and NAD+ content. Materials and Methods: Wistar albino rats were randomly distributed in four
groups: Control group, treated with cisplatin, tannic acid, and cotreated with tannic acid and cisplatin. The drugs
were injected intra-peritoneal. Animals were treated according to regulations of National Centre of Bioethics
(Armenia). Cell nuclei were isolated according to standard procedure. PARP 1 activity was evaluated by NAD+
consumption. PARG protein was estimated by sandwich Elisa method. Data are expressed as mean ± s.d. Statistical
differences in the results between groups were evaluated by the Student’s t-test. A probability (P) value of < 0.05
was considered significant. Key Results: Cisplatin and tannic acid displayed hepatotoxic effects in rat liver in 48
h after treatment. Although treatment of rats either with cisplatin or TA downregulated NAD+ and PARG content
in liver nuclei, the drugs exhibited oppositely directed effects on PARP 1 activity. Cotreatment with cisplatin
and TA-stimulated PARP 1 activity in liver nuclei did not affect the basal level of NAD+ and prevented drastic
decrease in PARG protein level. Conclusions: Cisplatin-induced inhibition of PARP 1 activity, NAD+, and PARG
content in liver nuclei were eliminated after cotreatment of rats with tannic acid.