The formation and persistence of carboplatin-DNA adducts in rats

Abstract

The formation and persistence of platinum-DNA adducts were studied with immuno(cyto)chemical methods in male and female Sprague-Dawley rats treated with a single i.p. dose of carboplatin. Linear dose-effect curves were observed for kidney and liver with an immunocytochemical assay using NKI-A59 antiserum that recognizes intrastrand cross-links. With this method, no staining of the nuclei due to platinum-DNA damage could be observed in the spleen, testis, uterus, or ovary after administration of up to 80 mg/kg carboplatin. A homogeneous staining of the nuclei in the liver was observed. The nuclear staining in the kidney was somewhat more intense but less homogeneous, with small groups of intensely stained nuclei occasionally being seen in the outer cortex. An approximately 15 to 20-times lower dose of cisplatin than of carboplatin was needed to reach equal staining levels in the liver and kidney. Plateau staining levels in both tissues were reached at between approximately 8 and 48 h after administration of the carboplatin. This was followed by a significant reduction in the kidney samples, whereas the staining levels in the liver section seemed to be more persistent. No major difference was observed between male and female rats in the formation and removal of DNA damage in these tissues. The levels of the various DNA adducts were measured with a competitive ELISA in liver, kidney, spleen, testis, and combined ovary/uterus samples collected at 8 and 48 h after carboplatin administration. At both 8 and 48 h, the highest platination levels were observed in the kidney, followed--in decreasing order--by the liver, combined uterus and ovary samples, spleen, and testis. At 8 h after administration of carboplatin, the relative occurrence of the bifunctional adducts Pt-GG (34%), Pt-AG (27%), and G-Pt-G (32%), was similar in all tissues. The same held for the monoadducts that amounted to about 7% of the total DNA platination. These data indicate that in the first few hours after carboplatin treatment, no preference for the formation of Pt-GG adducts was observed, which confirms our earlier observations obtained with cultured cells. When the total DNA-platination levels (calculated from the sum of the adducts) seen at 8 and 48 h after treatment were compared, a substantial decrease in DNA platination was observed in the kidney (37%), liver (30%) and ovary/uterus (39%), whereas the repair levels in the testis (9%) and, probably, the spleen (18%) were substantially lower. In all tissues studied, only the relative occurrence of the Pt-GG adducts increased between 8 and 48 h, and as a result, at 48 h, after carboplatin administration the Pt-GG adduct was the major adduct persisting in the DNA samples.

Comprehensive analysis of DNA methylation and gene expression of rat liver in a 2-stage hepatocarcinogenesis model

“…In addition, unique clusters consisting of carcinogenic compounds were also observed using the same set of genes (Fig. 2C), such as genotoxic 2-acetamidofluoren (Strom et al, 1983), carboplatin (Blommaert et al, 1996) and cisplatin (Giurgiovich et al, 1997), oxidative stress-inducing thioacetamide (Akbay et al, 1999) and methapyrilene (Ratra et al, 1998), alkylating nitrosourea lomustine (Dolan et al, 1990), Ames positive dantrolene (Snyder and Green, 2001), methyl-depleting ethionine (Shivapurkar et al, 1984), estrogen suppressor tamoxifen (Pogribny et al, 2007), and nitrosoconvertible ajmaline (Brambilla and Martelli, 2007). Although these compounds are not clearly defined as hepatocarcinogens, it should be noted that potentially carcinogenic compounds with different modes of action were closely clustered.…”

Dose Response of Carboplatin‐Induced Nephrotoxicity in Rats

“…platinum content in kidney tissues of rats in response to graded doses of carboplatin. Earlier studies had shown that carboplatin is toxic at a dose of (100-200 mg/kg, intraperitoneally) to rats (Kimura et al 1989;Nonclercq et al 1989;Haragsim & Zima, 1992;Blommaert et al 1996;Husain et al 2001). These doses are equivalent to the clinical therapeutic doses of carboplatin in cancer patients (Bishop 1992;Bohm et al 1999;Wandt et al 1999;Maldoon et al 2000).…”

“…Clinically, treatment with carboplatin significantly reduced glomerular filtration rate and serum magnesium in children (English et al 1999). In addition there is a high degree of platinum-DNA adduct persistence in kidneys subsequent to carboplatin administration in cancer patients (Poirier et al 1992;Blommaert et al 1996). Our recent study demonstrated that carboplatin at doses of (192 and 256 mg/kg, intraperitoneally) caused hearing loss and oxidative injury to cochlea in rats (Husain et al 2001).…”

Melatonin and Fertoprotective Adjuvants: Prevention against Premature Ovarian Failure during Chemotherapy

“…First, alkylating molecules, such as cyclophosphamide, have significant damaging effects on ovarian tissue [14,15,16], and are responsible for the highest rates of age-related ovarian failure [12]. Second, platinum-based molecules, such as cisplatin, cause amenorrhea [17,18], and induce DNA damage in the ovary through c-Abl tyrosine kinase inhibition and p63 activation [19,20]. Cisplatin also induces aneuploidy in oocytes and early embryonic death [21].…”