Increased Oxidative/Nitrosative Stress in Bitches with Several Tumors - Veterinary Science - page 86

ROS Reactive oxygen species

SOD Superoxide dismutase

14.1 Introduction

Reactive oxygen species (ROS) and nitrogen species together with superoxide and
hydroxyl radicals and hydrogen peroxide play key roles in carcinogenesis (Borek
1983 ). Their toxicity is based on the ability to induce lipid peroxidation, resulting in
damage to cell membranes, proteins, polysaccharides, and nucleic acids. It has been
shown that the production of ROS is increased in tumor cells, leading to oxidative
stress responsible for DNA damage and genomic instability and possibly favoring
tumor progression (Suh et al. 1999 ). In addition, during tumor progression, high
levels of ROS are responsible for the activation of transcription factors, such as
nuclear factor (NF)- B activator protein I (Arnold et al. 2001 ). Our recent research

has shown, in lymphocytes from patients with chronic myeloid leukemia, calcium
channel hypofunction due to cellular oxidative stress (Ciarcia et al. 2010 ).
The objective of this study was to evaluate the expression of markers of oxidative
stress in dogs suffering from breast adenocarcinoma, hemangiopericytoma, and
histiocytoma.

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14.2 Materials and Methods

Thirty dogs of different breeds, aged between 6 and 13 years, including eight
patients with breast adenocarcinoma, six with histiocytoma, five with hemangio-
pericytoma, and 11 controls were used in this study. The diagnostic findings were
provided by the Surgical Clinic of our Faculty. Blood samples were collected in
heparinized tubes. The plasma obtained was used for thiobarbituric acid, nitrite,
and nitrate assays and for CAT, SOD, and GPx assays. Bitches, before surgery,
were premedicated with atropine sulfate at a dose of 0.05 mg/kg administered
subcutaneously with a combination of 20 g/kg medetomidine and 0.2 mg/kg

acepromazine administered intramuscularly. Anesthesia was performed with
propofol injected at a dose of 7 mg/kg intravenously (bolus) and maintained with
isoflurane in O 2 . At the end of surgery, a portion of tumor tissue was removed and
stored at

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80 C. The samples were then thawed and homogenized in a solution of
50 mM potassium phosphate and 0.1% Triton (pH 7.0). The homogenates were
centrifuged at 15,300 rpm for 30 min at 4 C, and the supernatant was used for
determining the activities of antioxidant enzymes and analytes. The CAT assay was
performed using a colorimetric method according to Ding et al. ( 2000 ), the SOD
assay using a colorimetric method according to Sun et al. ( 1988 ), and the GPx assay
using a colorimetric method according to Mannervik et al. ( 1985 ). Lipid peroxida-
tion was determined by the measurement of MDA through the thiobarbituric acid