Effects of 9-cis-retinoic acid on the insulin-like growth factor axis in former smokers.
OBJECTIVE
Insulin-like growth factor (IGF) axis has been associated with the risk of lung cancer. 9-cis-retinoic acid (9-cis-RA) has shown potential chemopreventive activities in former smokers. This study was designed to evaluate the effects of 9-cis-RA on IGF axis in former smokers to identify any benefit the retinoid may have in preventing lung cancer.


METHODS
Serum concentrations of IGF-I, IGF binding protein (IGFBP)-3, and their molar ratio (IGF-I/IGFBP-3) were measured with radioimmunoassay kits in stored blood samples from the participants of an original chemoprevention trial. The participants had ceased smoking for at least 12 months and were randomly assigned to receive 3 months of daily oral 9-cis-RA (100 mg) or placebo. All statistical tests were two-sided.


RESULTS
A total of 111 samples from the study's baseline and 84 samples from the 3 months treatment were analyzed. The serum concentrations of IGF-I and IGF-I/IGFBP-3 at baseline were significantly lower in female than in male participants. After 3 months of treatment, the serum level of IGF-I and IGF-I/IGFBP-3 were significantly lower in the 9-cis-RA group than in the placebo group (P = .03 and P < .01, respectively), but the IGFBP-3 level was significantly higher (P = .03).


CONCLUSIONS
9-cis-RA treatment modulated the IGF axis in former smokers, suggesting that the IGF axis is a potential target for the chemopreventive activities of 9-cis-RA and that the serum concentrations of IGF, IGFBP-3, and IGF-I/IGFBP-3 could serve as surrogate end point biomarkers of 9-cis-RA treatment.
Department of Thoracic/Head & Neck Medical Oncology, and Program in Cancer Biology, Unit 432, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA. hlee@mdanderson.org
Ho-Young
HY
Lee
Yoon Soo
YS
Chang
Ji-Youn
JY
Han
Diane D
DD
Liu
J Jack
JJ
Lee
Reuben
R
Lotan
Margaret R
MR
Spitz
Waun Ki
WK
Hong
D000328:Adult; D000368:Aged; D000077556:Alitretinoin; D015415:Biomarkers; D005260:Female; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010919:Placebos; D011863:Radioimmunoassay; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D012907:Smoking / Q000009:adverse effects*; D014212:Tretinoin / Q000494:pharmacology*
D015415:Biomarkers; D018972:Insulin-Like Growth Factor Binding Protein 3; D010919:Placebos; D018168:Receptors, Retinoic Acid; C082925:retinoic acid receptor beta; D000077556:Alitretinoin; D014212:Tretinoin; D007334:Insulin-Like Growth Factor I