Mid-Kentucky Kennel Club CELLULAR OXIDATIVE STRESS & CANCERS

July 22, 2018

W. Jean Dodds, DVM & Denis Callewaert, PhD Hemopet

What Causes Diseases like Cancer ?

v Environment • cancer incidence much greater in

industrial areas

v Diet & Exercise• 20 - 60% of cancers are related

to diet & nutritional factors

• obesity is a main factor

v Genetics• estimated to explain only ~ 5% of cancers

Disease Mechanisms

v Chronic diseases: common factors• Oxidative stress and chronic, low-grade inflammation are silent

processes that are significantly impacted by diet, lifestyle and environmental factors

• Both have been proven to play major roles in the pathogenesis of a range of chronic diseases in animals and humans

Oxidative Stress & Diseases

Oxidative Stress vWhat is it?

• Reactive oxygen species are byproducts of normal metabolism

• Low levels play important roles in the regulation of metabolism

• Can react with and damage a wide range of biomolecules including DNA, proteins and lipids

• Oxidative stress is a condition wherein reactive oxygens are produced faster than they are neutralized by the body’s natural protective mechanisms

• Moderate amounts are important regulatory mediators in cell signaling processes

• This physiologic mechanism drives vital cellular functions

Cellular Oxidative Stress & Chronic Disease

v Oxygen-derived free radicals always accompany mitochondrial energy production

v Creating free radicals causes cell toxicity

v Even in healthy state, ~ 25% of oxygen intake forms free radicals

v In unhealthy states, up to 75% of oxygen becomes free radicals

v Common causes of oxidative stress: toxemia, infections, hypoxia-ischemia, hyperglycemia, xenobiotics (drug metabolism), hyperlipidemias, hyperproteinemias, cancers, phagocytic and immune reactions, and high metabolic rates

v Aging tissues under oxidative stress

(Mandelker, JAHVMA, 41:22-24, Winter , 2016)

Endogenous Antioxidants

v Antioxidant Enzymes § Catalase, superoxide dismutase, glutathione reductase.§ Expression altered by diet, exercise, aging

v Free Radical Scavengers§ Uric acid (in blood), Albumin, Bilirubin, Glutathione (in cells)

Antioxidants – Diet & Lifestyle

v Dietary antioxidants• Supplemental vitamin E and/or selenium no effect at low doses• Lots of other supplements in diet, including vitamin C, zinc, co-enzyme

Q10, alpha -lipoic acid, flavonoids in various fruits and vegetables • Need to be replenished

[Mandelker, JAHVMA , 41:22-24, Winter 2016]

v Exercise and antioxidant activity• Increased respiration rate increases level of natural antioxidant defenses• Over exercising (prolonged oxidative stress) can lead to inflammation

and disease

Inflammation: The Fire Within

v What is inflammation? • Physiological response to injury, infection, malignancy• Classic signs include fever, redness, swelling• Many molecules and cells involved (e.g. cytokines, eicosanoids)

v Acute Inflammation – necessary to protect the body

v Chronic inflammation - associated with many diseases• Cardiovascular diseases• Inflammatory bowel disease• Many types of cancer• Macular degeneration

v Anti-inflammatory agents can prevent/slow disease progression

Oxidative Stress & Inflammation

v Impaired Renal Function in Dogs• Dogs with impaired renal function of various causes had markedly

higher expression of 3 cytokines and 5-lipoxygenase compared to healthy dogs

• Elevated cytokines included: interleukins 1-alpha and 1-beta, and transforming growth factor-beta

• These elevated markers are part of the cellular inflammatory response to both acute kidney injury and chronic kidney disease

[Nentwig et al, AJVR, 77:218-224, 2016]

Prevention & Risk Assessment

A Paradigm Shift in Medicine •••

From Reactive to Proactive: Preventive Medicinev New interest in preventative medicine

• Traditional diagnostics probe for disease, not health

• Should �health� only be assessed by the absence of disease?

v Personal approaches• Diet, lifestyle, exercise, and nutritional supplements impact health

v New ways to check health• Not just blood pressure, cholesterol level, mammogram, etc

v Tests for risk indicators - altered by genetics, diet & lifestyle• Oxidative stress & Antioxidant activity

• Inflammatory status

v Several well-established tests for these indicators• Don�t diagnose specific diseases

• Don�t fit current laboratory / FDA / insurance paradigms

• Not readily accessible to clinicians

Tests to Assess Human & Animal “Wellness”

v Available Now• Good tests for antioxidant activity & for oxidative damage• Measured in serum , saliva, urine

v In development• Oxidized proteins as indicators of tissue-specific damage• Inflammatory status biomarker(s)• Cancer resistance indicator(s)

v Further down the road• MicroRNA Analysis: Recently discovered regulator of gene translation

• Metabolic Profiling: analysis of �metabolic fingerprints� of >1,000 molecules in urine

Can drugs prevent some chronic diseases ?

Can nutraceuticals prevent some chronic diseases ?

The Answer is YES for both !

Cancer Chemoprevention

vNSAIDs• Well documented - if not widely known

• Aspirin, coated aspirin, ibuprofen, naproxen

• NOT Tylenol (acetaminophen)

vNutraceuticals - some data• Curcumin, soy isoflavones, resveratrol, and others

vGenes turned on by cancer chemopreventatives• NSAIDs and nutraceuticals activate some genes

Fish Oils - Antioxidant or Anti-Inflammatory ?v Omega-3 Fatty Acids

• Found in fish, flax and some other plants• Popular nutraceutical• Long thought to act just as oxygen radical scavengers

v Fish vs Meat Diets: Japanese Americans• Japanese who eat a western diet have higher CVD and colon cancer• Long thought to involve unsaturated fatty acids in meat

§ Arachidonic acid is substrate for COX-1 and COX-2§ Association of COX with CVD and cancer

• But maybe due to less fish in the diet§ DHA (omega-3 fatty acid) is converted by COX-2 to Neuroprotectin -

- helps reduce stroke damage; may have other benefits§ DHA actually better substrate for COX-2 than AA§ Just beginning to be understood

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Premium Dry Economy Dry PremiumCanned

EconomyCanned

Rancidity, MDA (mg/L, 5X)

Antioxidants (µM, Trolox Equivalents)

Typical Commercial Dogs Foods

Lipid Peroxidation in Kibble ProductsSource: American Oil Chemists Society

• Catalase

• Superoxide Dismutase (SOD)

• Glutathione (GH)

• Isoprostanes = a group of prostaglandin-like compounds produced by the reaction of free radicals with arachidonic acid

Note: Tumor Necrosis Factor –alpha levels were below detection in all 3 diets

Nrf-2 Dependent Biomarkers

Future DirectionsNutrigenomics and Canine Health

v Simple tests for rancidity and antioxidant capacity should permit dog owners and breeders to select better foods

• Monitor for antioxidant levels

• Evaluate rancidity due to oxidation of foods – especially kibble products – over time

v Development of functional foods, e.g. those containing natural Nrf-2 activators, has great promise

Some Nrf-2 Activators in Foods

Future DirectionsNutrigenomics for Canine Healthv The effects of other dietary variables, including functional

foods and saturated vs unsaturated fats need to be evaluated

vOlder, less healthy animals more likely to exhibit higher levels of disease-related biomarkers. Also more likely to benefit from induction of antioxidant pathways

vNewer biomarkers, including metabolomic analyses, isoprostanes and miRNAs plus provide earlier assessment of diet-related health effects in younger animals