Dietary Fat and Breast Cancer: A Controversial lssue

The janus face of lipids in human breast cancer: how polyunsaturated Fatty acids affect tumor cell hallmarks

For several years, lipids and especially n - 3 and n - 6 polyunsaturated fatty acids (PUFAs) receive much attention in human health. Epidemiological studies tend to correlate a PUFA-rich diet with a reduced incidence of cancer, including breast cancer. However, the molecular and cellular mechanisms supporting the effect of PUFAs in breast cancer cells remain relatively unknown. Here, we review some recent progress in understanding the impact that PUFA may have on breast cancer cell proliferation, apoptosis, migration, and invasion. While most of the results obtained with docosahexaenoic acid and/or eicosapentaenoic acid show a decrease of tumor cell proliferation and/or aggressivity, there is some evidence that other lipids, which accumulate in breast cancer tissues, such as arachidonic acid may have opposite effects. Finally, lipids and especially PUFAs appear as potential adjuvants to conventional cancer therapy.

Effect of linoleic acid on proliferation and gene expression in the breast cancer cell line T47D

Human and animal studies have linked n-6 polyunsaturated fatty acids with mammary carcinogenesis. We investigated the cellular and molecular effects of linoleic acid on the human breast cancer cell line T47D. Linoleic acid had a stimulatory effect on the growth of T47D cells, associated with an increase in the proportion of cells in the S phase of the cell cycle. Microarray, functional group and quantitative PCR analyses indicate that linoleic acid may affect T47D cell growth by modulation of the estrogen receptor (ERalpha), the G13alpha G protein, and p38 MAP kinase gene expression as well genes involved in RNA transcription and cell cycle regulation.

Dietary docosahexaenoic acid suppresses N-methyl-N-nitrosourea-induced mammary carcinogenesis in rats more effectively than eicosapentaenoic acid

We compared the effects of identical amounts but different proportions of dietary n-3 polyunsaturated fatty acids (PUFAs) on N-methyl-N-nitrosourea (MNU)-induced mammary cancer in a rat model. The ability of dietary docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) to suppress mammary cancer was evaluated. Female Sprague-Dawley rats were randomly assigned to three groups and maintained on diets containing 10% fatty acid consisting of EPA, a 1:1 mixture of EPA-plus-DHA, or DHA. The experimental diet was started after administration of MNU at 49 days of age, and the rats were maintained on the respective diets until the largest mammary tumor reached >1 cm in diameter or until the end of the study period (20 wk after MNU). All histologically detected mammary carcinomas were evaluated, irrespective of size. The DHA diet was associated with significant suppression of the carcinogenic effect of MNU compared with the EPA and EPA-plus-DHA diets: tumor incidence decreased to 23% (3/13) compared with 73% (11/15) and 65% (12/17) (P < 0.01 and P < 0.05, respectively); tumor multiplicity decreased to 0.23 compared with 1.67 and 1.59 (P < 0.01 and P < 0.05, respectively). There was no significant difference in tumor latency among the DHA, EPA, and EPA-plus-DHA groups (119, 105, and 117 days, respectively). Over 20 wk, the fatty acid composition of serum and mammary fat tissue reflected differences in the dietary n-3 PUFAs. Although DHA suppressed MNU-induced mammary carcinogenesis more effectively than EPA, generalized steatosis including mammary fat tissue appeared in all three groups.

Adenoviral GM-CSF Gene Transduction into Breast Cancer Cells Induced Long-Lasting Antitumor Immunity in Mice

BACKGROUND: Immunogene therapy is regarded as a novel treatment that overcomes the limitation of preexisting adjuvant therapies and demonstrates the potential for the total elimination of cancer cells by affecting concealed tumor cells. The aim of this study was to examine the enhancement of antitumor immunity of irradiated granulocyte-macrophage colony-stimulating factor (GM-CSF) gene-transduced mouse breast cancer cells. METHODS: To study prophylactic vaccine effects, Balb/c mice were vaccinated subcutaneously with saline or irradiated mouse breast cancer cells (BalbMC, 1 x10&sup6; /mouse) infected with or without recombinant adenovirus harboring the GM-CSF gene (Adv/GM-CSF) on day-7. Mice were challenged with parental cells (1x10&sup5;/mouse) on day 0 in the flank opposite the vaccination site. RESULTS: BalbMC cells secreted GM-CSF after infection with Adv/GM-CSF. Vaccination with irradiated GM-CSF-secreting BalbMC completely protected syngeneic mouse challenged with live parental cells. On the other hand, vaccination with irradiated BalbMC protected 60% of mice from tumor development after challenge with parental cells. None of the tumor-free mice initially vaccinated with irradiated GM-CSF-producing BalbMC cells developed tumor upon repeated challenge with parental cells during the entire observation period. CONCLUSION: Our study demonstrated the feasibility of this immunotherapeutic approach as a novel adjuvant therapy after surgery for breast cancer.

Risk Factors for Breast Cancer among Japanese Women: A Case-Control Study in Ibaraki, Japan

BACKGROUND: The number of epidemiologic studies on breast cancer risk factorsin Japanese women is still quite limited. Our objective was to clarify the relationship between lifestyle, body size and breast cancer risk. METHODS: A matched case-control study was conducted in Ibaraki, Japan. The participants were 148 women aged 26-69 diagnosed with breast cancer at Tsukuba University Hospital or Tsukuba Medical Center Hospital between January, 1990 and March, 1997. Two controls were individually matched to the cases by age and residence. A self-administered questionnaire was used to obtain information on the family history of breast cancer, reproductive history, education, body size and lifestyle factors. Conditional logistic regression analysis was used to estimate oddsratios (ORs)and 95% confidence intervals (95% CI). RESULTS: After adjustment for potential confounders, heavy weight and higher body mass index were associated with an increased risk of breast cancer among postmenopausal women (OR = 1.76, 95% CI = 0.69, 4.48; OR = 1.57, 95% CI=0.61, 3.99, respectively). Current or ex-smokers were found to be at an increased risk for breast cancer (OR = 3.33; 95% CI = 1.63, 6.80). Women who take hot baths had a decreased risk for breast cancer (OR = 0.67; 95% CI = 0.43, 1.06). Recreational physical activity was associated with a reduced risk of breast cancer (PTrend = 0.005).OR for breast cancer among physically active women was 0.36 (95% CI = 0.19, 0.70), as compared with inactive women. Taller women had an increased risk of breast cancer relative to shorter women (OR = 1.49; 95% CI = 0.83, 2.70). No significant association between alcohol consumption and breast cancer risk was detected. CONCLUSION: Our results suggest that several potentially modifiable lifestyle factors may be useful for the prevention of breast cancer.