Preclinical and clinical evaluation of broccoli supplements as inducers of glutathione S-transferase activity.
Previous studies suggest that cruciferous vegetables may provide protection against carcinogen exposure by inducing detoxification enzymes. ICR(Ha) mice were gavaged with broccoli tablets (1 g/kg), and colon tissues were collected after treatment. Glutathione S-transferase (GST) activity was assayed and peaked on days 1 and 2 after treatment, respectively (P = 0.03). Elevations in GST activity were attributed to the increased expression of mu and pi. These data supported a clinical assessment of broccoli supplements. Twenty-nine subjects at increased risk for colorectal cancer were randomized to group 1 (no cruciferous vegetables) or group 2 (broccoli supplements, 3 g/day) for 14 days. Blood samples and colon biopsies were obtained pre- and postintervention. No significant difference was observed between the GST activities of the control and broccoli supplementation groups posttreatment. Mean lymphocyte GST activity was 107% of baseline in the broccoli supplementation group (range, 79-158%) and 102% of baseline in the control group (range, 75-158 percent;). Correlation of the GST activities of blood lymphocytes and colon mucosa taken simultaneously suggested that the GST activity of blood lymphocytes may be used as a biomarker of the responsiveness of colon tissue to chemopreventive regimens. Future clinical studies evaluating cruciferous vegetables should consider using concentrated dietary supplements in subjects with a previous history of colorectal cancer.
Clapper
M L
ML
Divisions of Population Science and Medical Science, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
Szarka
C E
CE
Pfeiffer
G R
GR
Graham
T A
TA
Balshem
A M
AM
Litwin
S
S
Goosenberg
E B
EB
Frucht
H
H
Engstrom
P F
PF
D000328:Adult; D000368:Aged; D000818:Animals; D001937:Brassica; D018890:Chemoprevention; D015179:Colorectal Neoplasms / Q000201:enzymology / Q000517:prevention & control; D019587:Dietary Supplements; D004790:Enzyme Induction; D005260:Female; D005753:Gastric Mucosa / Q000201:enzymology; D005982:Glutathione Transferase / Q000096:biosynthesis*; D006801:Humans; D008214:Lymphocytes / Q000201:enzymology; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008875:Middle Aged; D012307:Risk Factors
D005982:Glutathione Transferase