Omega-3 fatty acids and cancer therapy

W. Elaine Hardman, Ph.D.Department of Biochemistry and Microbiology

Marshall University School of MedicineHuntington, West Virginia

Outline

•What are omega 3 fatty acids?

•Pre-clinical evidence for benefit of n-3 fatty acids during cancer therapy

• Potential mechanisms for therapeutic benefit of n-3 fatty acids

• Clinical evidence for benefit of n-3 fatty acids during cancer therapy

Major fat types

C

O

OHStearic18:0

5 37911131517

Saturated fat

Monounsaturated fat

OHC12 918 16

O

Oleic (OA) 18:1n-9

Linoleic (LA)

18:2n-6

O

18

C13 12 9 OH

OHC12 9

O

18 15Linolenic(LNA) 18:3n-3

Polyunsaturated fats

Pre-clinical evidence for benefit of omega-3 fatty acids during cancer therapy

Supplementing the diet with omega-3 fatty acids may suppress the growth of existing cancers and may prevent or slow metastasis

Omega 3 fatty acids may increase the efficacy of chemo- or radiation therapy

Hormone responsive tumors such as:

breast, prostate and colon cancers

seem especially sensitive to omega 3 fatty acids.

However, in animal models, lung cancer growth has been also slowed by omega 3 fatty acids.

0 5 10 15 20 25 30 350

100

200

300

400

500

600

700

800

900

COCOdox

N-3N-3dox

MDA-MB 231 growth after initiation of DOX

Growth rate mm3/day ± SEM24.2 ± 1.1 3.3 ± 0.6

5.1 ± 0.4-0.1 ± 0.1

Number days after initiation of DOX

Mea

n t

um

or

size

(m

m3)

Corn oil diet

Omega 3 diet

0 10 20 300

250

500

750

20% Corn oil

19 % Fish oil19% Fish oil and ferric citrate

Beginning of DOX and ferric citrate

Phase II time of treatmentPhase I

20% Corn oil (no DOX treatment)

Diet

Growth of A549 lung cancer xenografts in nude mice

Days after initiation of fish oil diet

Mea

n tu

mor

siz

e (m

m3)

5 10 15 20

-75

-50

-25

0

25

50

75

Days after start of CPT-11

Control, no CPT-11

Corn oil, CPT-11

3% Fish oil, CPT-116% Fish oil, CPT-11M

ean

tum

or

size

(m

m3)

MCF7 Tumors

In animal models, the efficacies of:

epirubicin (Bougnoux),

5-fluorouracil (Hochwald),

mitomycin C (Pardini),

araC (Cha) and

tamoxifen (DeGraffenried)

have also been enhanced in the presence of an omega 3 dietary

supplement.

Omega 3 fat may increase radiation sensitivity of cancer cells

Irradiation reduced the size of chemically induced rat mammary gland tumors (Colas, et al).

Percent decrease in size oftumor 12 days after radiation

Control DHA fed0

10

20

30

40

50

60

CO

CO 24

hrs p

ost r

ad n-3

n-3

24 h

rs p

ost r

ad0.0

0.5

1.0

1.5a

a,b

b,c

c

Met

aph

ase

ind

ex

Metaphase index in MDA-231 tumors of mice fed omega 6 or omega 3 diets with or without gamma irradiation

Omega 3 fatty acids may reduce cancer cachexia

Cachexia – from Greek kachexia - bad condition

General physical wasting and malnutrition

Usually associated with increasing tumor mass. Cannot be corrected by increasing food intake

Cancer cachexia

Omega 3 Omega 6

Potential mechanisms for therapeutic benefit

O x i d a t i v e S t r e s sL P S , i r r a d i a t i o n , U V , F e a n d o t h e rp r o o x i d a n t s o r c h e m o t h e r a p e u t i c d r u g s

R O S

V i t E

P P A R • c i s r e t i n o l r e c e p t o r

P e r o x i s o m eβ - o x i d a t i o n

l i p i d b i n d i n g p r o t e i n sP 4 5 0 i s o z y m e s

A O E s

P P R E sg e n e s

N u c l e u s

I κ B • N F κ B

P O 4

N F κ B

g e n e s

E P A o r A A

I L - 1I L - 6I L - 1 2M M I FT N F α

T B X 2

L T B 4

P G E 2

P G E 3

L T B 5

T B X 3

N S A I D S

A A o r E P A

p r o l i f e r a t i o ni n f l a m m a t i o n

e n h a n c e s p l a t e l e t a g g r e g a t i o np r o i n f l a m m a t o r yp r o p r o l i f e r a t i v e

a n t i i n f l a m m a t o r ya n t i p r o l i f e r a t i v er e t a r d s p l a t e l e t a g g r e g a t i o n

I κ B - P

N F κ B - R E s

C o r n o i l

F i s h o i l

P L A2 o r P L C

C O X - c y c l o o x y g e n a s eL O X - l i p o x y g e n a s e

i n d u c e

C O X 2o r

L O X

E P A

A A

Da m

a g e :L i p

i ds D a m a g e :

P r o t e i n sD N A

V i t . E

i f f r o mE P A

i f f r o mA A

a c t i v a t e

n - 3 P U F A8 - H E T E

W Y - 1 4 , 6 4 9c l o x i b r a t e

s o m e N S A I D SD H E A S

E P A

M o d e l f o r A c t i o n s o f n - 3 P U F A i n c e l l s

Free radicals

O2-Superoxide

Hydroxyl HO•

Hydroperoxyl HO2•

Hydrogen peroxide H2O2

Lipid peroxide LO2H

Reactive nitrogen speciesThiyl

Membranes

Mitochondria

Enzymes

ChromosomesDNA

Scientific American, Dec. 1992

Defenses from oxidative damage

Endogenous antioxidative enzymes: Superoxide dismutaseCatalaseGlutathione peroxidase

Exogenous antioxidants: Vitamin E and beta carotenesUric acid and Vitamin CMetal chelators

How could the efficacy of chemotherapy be altered without causing additional damage to normal cells?

1. Most chemotherapeutic drugs cause oxidative damage to cells.

3. Fat composition of all tissues can be altered by changing the fats content of the diet.

5. Activity of endogenous antioxidative enzymes can be altered in cells.

A h i g h e r a c t i v i t y o f S O D a n d l o w e r a c t i v i t y o f G P X w o u l d r e s u l t i n t h ea c c u m u l a t i o n o f H 2 O 2 . I f c a t a l a s e i s n o t i n c r e a s e d , a c c u m u l a t e d H 2 O 2

c o u l d r e a c t w i t h F e 2 t o y i e l d h i g h l y r e a c t i v e O H a n d O H + F e 3 .··

P r o d u c t o fr e s p i r a t o r yc h a i n

O 2· -

G S H 2 G S H

S O DH 2 O 2

F e 2 O H + O H + F e 3· ·G P X

2 H 2 0

G S S G

0

10

20

A

B B

No

spec

ime

n

(me

an±

SE

M u

nits

/mg

pro

tein

)

0

10

20

30

40

50

0

5

10

15

0

10

20

30

No

spec

imen

(mea

n±

SEM

mm

ol H

2O2

deco

mpo

sed/

min

/mg

prot

ein)

0

50

100

150 A A

BB

0.0

2.5

5.0

7.5

Corn

oil

Corn

oil, d

oxFOC

FOC, dox

0

250

500

750

No

sp

eci

me

n

(me

an±

SE

Mµm

ol

b-N

AD

P o

xid

ize

d/g

pro

tein

)

Corn

oil

Corn

oil, d

oxFOC

FOC, dox

0

250

500

750

1000

A

A

B

B

Corn

oil

Corn

oil, d

oxFOC

FOC, dox

0

25

50

75

100

TUMOR LIVER COLON

Superoxide dismutase

Catalase

Glutathione peroxidase

Antioxidant enzyme activity in mice fed 5% CO or 3% FOC/2% CO

diets with or without DOX treatment for 2 wks

DHA inhibits eicosanoid synthesis from AA(Rose and Connolly, 1999)

EPA effectively out-competes AA for COX activity(Needleman, P., 1979; Yang, P., et al., 2002)

EPA is a better substrate for COX 2 than AA. (Yang, P., et al., 2002)

O x i d a t i v e S t r e s sL P S , i r r a d i a t i o n , U V , F e a n d o t h e rp r o o x i d a n t s o r c h e m o t h e r a p e u t i c d r u g s

R O S

V i t E

P P A R • c i s r e t i n o l r e c e p t o r

P e r o x i s o m eβ - o x i d a t i o n

l i p i d b i n d i n g p r o t e i n sP 4 5 0 i s o z y m e s

A O E s

P P R E sg e n e s

N u c l e u s

I κ B • N F κ B

P O 4

N F κ B

g e n e s

E P A o r A A

I L - 1I L - 6I L - 1 2M M I FT N F α

T B X 2

L T B 4

P G E 2

P G E 3

L T B 5

T B X 3

N S A I D S

A A o r E P A

p r o l i f e r a t i o ni n f l a m m a t i o n

e n h a n c e s p l a t e l e t a g g r e g a t i o np r o i n f l a m m a t o r yp r o p r o l i f e r a t i v e

a n t i i n f l a m m a t o r ya n t i p r o l i f e r a t i v er e t a r d s p l a t e l e t a g g r e g a t i o n

I κ B - P

N F κ B - R E s

C o r n o i l

F i s h o i l

P L A2 o r P L C

C O X - c y c l o o x y g e n a s eL O X - l i p o x y g e n a s e

i n d u c e

C O X 2o r

L O X

E P A

A A

Da m

a g e :L i p

i ds D a m a g e :

P r o t e i n sD N A

V i t . E

i f f r o mE P A

i f f r o mA A

a c t i v a t e

n - 3 P U F A8 - H E T E

W Y - 1 4 , 6 4 9c l o x i b r a t e

s o m e N S A I D SD H E A S

E P A

M o d e l f o r A c t i o n s o f n - 3 P U F A i n c e l l s

Residual cancer cells must multiply for the tumor to reoccur or for metastatic sites to grow

LA and AA activate PKC stimulating mitosis (Hannun et al., 1986)

N-3 fatty acids decrease activity of ras (Collett et al, 2001) and AP-1 (Liu, et al., 2001)

AA products of COX and LOX increase mitosis; EPA and DHA decreased mitosis and inhibited growth of breast and colon cancer cells (Rose & Connolly, 1990; Buckman, 1991; Abou-El-Ela, 1989)

Functional apoptotic pathways help control cell growth

COX-2 expression downregulates apoptotic pathway (Tsujii & DuBois, 1995, Connolly & Rose, 1998)

NFκB activation blocks apoptosis (Schwartz, 1999), n-3 fatty acids block NFκB activation

DHA inactivated Bcl-2 family genes and increased transcription of genes and transcription factors that induce apoptosis (Narayanan, et al, 2001; Chiu, et al., 1999)

Terminally differentiated cells don’t multiply

Omega -3 fatty acids induced differentiation of breast cancer cells (Wang, 2000)

Angiogenesis must occur for tumors to grow and metastasize

n-6 products of COX-2 and 12-LOX stimulate angiogenesis, n-3 products do not (Form & Auerback, 1983; Connolly & Rose, 1998)

Omega 3 fatty acids decrease estrogen metabolism

PGE2 activates P450 aromatase to increase estrogen production (Noble, et al. 1997)

Shift in estrogen metabolism towards 16α-hydroxylation increases the formation of aberrant hyperproliferation in breast. Omega-3 supplements decreased 16α-hydroxylation (Osborne, et al. 1988)

Summary: N-3 fatty acids may be detrimental to growth of metastatic or residual cancer cells by:

• Altering eicosanoid metabolism

• Slowing cancer cell mitosis

• Increasing cancer cell death

• Inducing differentiation

• Suppressing angiogenesis

• Altering estrogen metabolism

Clinical evidence of benefit

Maximum tolerated dose

Burns, et al. Phase I clinical study of fish oil fatty acid capsules for patients with cancer cachexia: cancer and leukemia group B study 9473. Clin Cancer Res. 5:3842, 1999

Univ. of Iowa Cancer Center

0.3 g/kg/day - 70 kg patient can consume up to 21 g/dayDose limiting toxicity was gastrointestinal, mainly diarrhea

Effects on cachexia

Barber, Fearon, Tisdale (Dept of Surgery, Univ of Edinburgh)

Various papers on cachexia in pancreatic cancer patients

• EPA supplement improved life span in pancreatic cancer patients even with no other treatment

• Patients consuming an n-3 containing supplement gained weight and quality of life was improved

• Patients excreted less IL-6 and less proteolysis inducing factor

Breast cancer

Bougnoux (Univ Tours) –localized breast carcinoma patients with higher levels of DHA in breast adipose tissue responded better to chemotherapy. Level of n-3 fatty acids was higher in patients with complete or partial remission than in patients with no response or tumor progression (p < 0.004)

Bagga (UCLA School of Medicine) – consumption of an n-3 supplement for 3 months significantly changed composition of breast adipose tissue. Breast adipose composition changed more rapidly than gluteal adipose composition.

Epidemiology studies Simonsen et al. Am J Epidemiology 147:342, 1998

4 of 5 centers ↑n3/n6 EURAMIC = ↓breast cancer risk

Goodstein et al. J Nutr 133:1409, 2003Premenopausal ↑n3/n6 = non significant ↓breast cancer riskPostmenopausal ↑n3/n6 = significant ↓breast cancer risk

Maillard et al. Int J Cancer 98:78, 2002 ↑DHA = significant ↓breast cancer risk ↑long chain n3/n6 = significant ↓breast cancer risk

Bagga et al. Nutr Cancer 42:180, 2002N6 fat significantly higher in breast cancer casesfor a given level of n6, higher EPA or DHA were protective

Pala et al J Natl Cancer Inst 93:1088, 2001↑DHA = significant ↓breast cancer risk

Summary

• Preclinical studies indicate that n-3 fatty acids should be beneficial for cancer treatment

• Mechanistic studies indicate feasible mechanisms for the influence of n-3 fatty acids on tumor growth, survival and response to chemotherapy

• Limited clinical studies that are available indicate that n-3 fatty acids have been beneficial during cancer therapy or may reduce risk for breast cancer

Bulldoggin’ Cancer