Il ruolo degli Omega nella terapia del cancroPresentation Transcript
Omega-3 fatty acids and cancer therapy W. Elaine Hardman, Ph.D. Department of Biochemistry and Microbiology Marshall University School of Medicine Huntington, West Virginia
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 Stearic 18:0 5 3 7 9 11 13 15 17 Saturated fat Monounsaturated fat OH C 12 9 18 16 O Oleic (OA) 18:1n-9 C O OH
Linoleic (LA) 18:2n-6 O 18 C 13 12 9 OH OH C 12 9 O 18 15 Linolenic (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.
Corn oil diet Omega 3 diet
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).
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
Free radicals O 2 - Superoxide Hydroxyl HO Hydroperoxyl HO 2 Hydrogen peroxide H 2 O 2 Lipid peroxide LO 2 H Reactive nitrogen species Thiyl
Membranes Mitochondria Enzymes Chromosomes DNA Scientific American, Dec. 1992
Defenses from oxidative damage Endogenous antioxidative enzymes: Superoxide dismutase Catalase Glutathione peroxidase Exogenous antioxidants: Vitamin E and beta carotenes Uric acid and Vitamin C Metal chelators
How could the efficacy of chemotherapy be altered without causing additional damage to normal cells?
Most chemotherapeutic drugs cause oxidative damage to cells.
Fat composition of all tissues can be altered by changing the fats content of the diet.
Activity of endogenous antioxidative enzymes can be altered in cells.
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)
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) NF B activation blocks apoptosis (Schwartz, 1999), n-3 fatty acids block NF B 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 PGE 2 activates P450 aromatase to increase estrogen production (Noble, et al. 1997) Shift in estrogen metabolism towards 16 -hydroxylation increases the formation of aberrant hyperproliferation in breast. Omega-3 supplements decreased 16 -hydroxylation (Osborne, et al. 1988)
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
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/day Dose 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, 2003 Premenopausal n3/n6 = non significant breast cancer risk Postmenopausal 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, 2002 N6 fat significantly higher in breast cancer cases for 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
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