Glyceollin-Elicited Soy Protein Consumption Induces Distinct Transcriptional Effects As Compared to Standard Soy Protein

Glyceollins are stress-induced compounds in soybeans
with bioactive
properties distinct from parent soy isoflavones. The goals of this
study were to evaluate the effects of dietary glyceollin-enriched
and standard soy protein isolates and identify candidate target pathways
of glyceollins on transcriptional profiles within mammary gland tissue.
Thirty female postmenopausal cynomolgus monkeys were randomized to
diets containing one of three protein sources for 3 weeks: (1) control
casein/lactalbumin (C/L), (2) standard soy protein containing 194
mg/day isoflavones (SOY), and (3) glyceollin-enriched soy protein
containing 189 mg/day isoflavones + 134 mg/day glyceollins (GLY).
All diets contained a physiologic dose of estradiol (E2) (1 mg/day).
All doses are expressed in human equivalents scaled by caloric intake.
Relative to the control C/L diet, the GLY diet resulted in greater
numbers of differentially regulated genes, which showed minimal overlap
with those of SOY. Effects of GLY related primarily to pathways involved
in lipid and carbohydrate metabolism, including peroxisome proliferator-activated
receptor (PPAR)-γ and AMP-activated protein kinase (AMPK) signaling,
adipocytokine expression, triglyceride synthesis, and lipase activity.
Notable genes upregulated by the GLY diet included PPAR-γ, adiponectin,
leptin, lipin 1, and lipoprotein lipase. The GLY diet also resulted
in lower serum total cholesterol, specifically nonhigh-density lipoprotein
cholesterol, and increased serum triglycerides as compared to the
C/L diet. No effects of GLY or SOY were seen on serum insulin, adipocytokines,
or vascular and bone turnover markers. These preliminary findings
suggest that glyceollin-enriched soy protein has divergent effects
from standard soy with some specificity for adipocyte activity and
nutrient metabolism.