[Effects of different dietary fatty acid on expression of nuclear receptor genes in breast cancer of rats].
OBJECTIVE
To study the effects of different dietary fatty acid on the expression of nuclear receptor genes in the breast cancer of rats.


METHODS
Fifty-day-old female Sprague-Dawley rats were fed on eight different diets containing following fatty acids: saturated fatty acid (SFA); monounsaturated fatty acid (MUFA); n-6 polyunsaturated fatty acid (PUFA); n-3 PUFA; 1:1 n-6/n-3; 5:1 n-6/n-3; 10:1 n-6/n-3; 1:2:1 S/M/P (n-6/n-3 at 1:1). The rats were given a single intraperitoneal injection of methyl-nitrosourea (MNU) at 50 mg/kg body weight to establish the rat model of mammary carcinogenesis, the ultrastructure changes of mammary gland cells in rats were observed by transmission electron microscope, the cell proliferation activity was detected by BrdU-labeled immunocytochemistry, and the expression of PPARbeta and PPARgamma mRNA were assayed by RT-PCR.


RESULTS
There was no breast cancer occurring in control groups and the MNU-treated n-3 PUFA group, and the ultrastructure and proliferation activity of mammary gland cells in these groups were normal. In contrast, there appeared obvious marker of adenocarcinomas in mammary gland cells of MNU-induced breast cancer, and a high cell proliferation activity was found in tumor growth-enhancing groups (SFA, MUFA, n-6 PUFA, 5:1 n-6/n-3, 10:1 n-6/n-3 and S/M/P, 21% - 22% of BrdU-labeled cells), while a low cell proliferation activity was detected in rats fed with 1:1 n-6/n-3 diet (13% of BrdU-labeled cells, P < 0.05). Moreover, peroxisome proliferator-activated receptors (PPARs), as important nuclear receptor genes of relating lipid metabolism, the expressions of PPARbeta and PPARgamma mRNA were significantly up-regulated in mammary adipose tissues of MNU-induced breast cancer as compared with the control groups, but the expression levels of peroxisome proliferator-activated receptors (PPARs) in rats fed with 1:1 n-6/n-3 group were lowest (P < 0.05).


CONCLUSIONS
The different dietary fatty acid compositions should diversely adjust the expression of PPARs gene in rats, which maybe have an important role in affecting incidence of breast cancer.
Wei
Na
N
Department of Nutrition and Food Hygiene, Third Military Medical University, Chongqing Key Laboratory of Nutrition and Food Safety, Chongqing 400038, China.
Mi
Man-tian
MT
Wang
Bin
B
Zhu
Jun-dong
JD
Zhu
Da-peng
DP
Yuan
Jia-lin
JL
D000818:Animals; D005227:Fatty Acids / Q000494:pharmacology*; D015525:Fatty Acids, Omega-3 / Q000494:pharmacology; D043371:Fatty Acids, Omega-6 / Q000494:pharmacology; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D005260:Female; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D008325:Mammary Neoplasms, Experimental / Q000235:genetics*; D047495:PPAR gamma / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley
D005227:Fatty Acids; D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6; D005231:Fatty Acids, Unsaturated; D047495:PPAR gamma; D012333:RNA, Messenger