K. Nesaretnam et al., Effect of a carotene concentrate on the growth of human breast cancer cells and pS2 gene expression, TOXICOLOGY, 151(1-3), 2000, pp. 117-126
Breast cancer is the most common cancer in women worldwide. The growth of b
reast cancer cells is either hormone-dependent or hormone-independent. Both
types are represented in vitro by the estrogen-receptor positive (ER +) MC
F-7 and the estrogen-receptor negative (ER -) MDA-MB-231 cell lines, respec
tively. The pS2 gene is an estrogen-regulated gene and serves as a marker f
or the ER + tumours. Carotenoids are pigments with anti-cancer properties b
esides having pro-vitamin A, antioxidant and free-radical quenching effects
. This study was designed firstly, to compare the effect of palm oil carote
ne concentrate with retinoic acid on the growth of the ER + PI and the ER -
MDA-MB-231 cells; and secondly to evaluate the effect of the palm oil caro
tene concentrate on the regulation of pS2 mRNA. The growth experiments were
performed with monolayer cells seeded in phenol red free RPMI 1640 culture
media and subsequently treated with varying concentrations of either retin
oic acid or palm oil carotenoids. The cell numbers were determined at the s
tart of each experiment and then at successive time intervals. The results
showed that the palm oil carotene concentrate caused dose-dependent inhibit
ion of estradiol-stimulated growth of MCF-7 cells but did not affect the pr
oliferation of MDA-MB-231 cells. Retinoic acid caused similar, albeit more
potent effects, as significant inhibition was observed at lower concentrati
ons than the palm oil carotenoids, in the pS2 gene expression experiment, c
ell monolayers were treated with the carotene concentrate(10(-6) M), either
with or without supplemented estradiol (10(-8) M), and subsequently the RN
A was extracted. Northern blotting was per-formed and the regulation of pS2
mRNA determined using a P-32-labelled pS2 cDNA probe. The results showed t
hat the palm oil carotene concentrate did not affect the expression of pS2
mRNA and are therefore independent of the: estrogen-regulated pathway. (C)
2000 Elsevier Science Ireland Ltd. All rights reserved.