Redox signalling to nuclear regulatory proteins by reactive oxygen species contributes to oestrogen-induced growth of breast cancer cells.

BACKGROUND: 17ß-Oestradiol (E2)-induced reactive oxygen species (ROS) have been implicated in regulating the growth of breast cancer cells. However, the underlying mechanism of this is not clear. Here we show how ROS through a novel redox signalling pathway involving nuclear respiratory factor-1 (NRF-1) and p27 contribute to E2-induced growth of MCF-7 breast cancer cells. METHODS: Chromatin immunoprecipitation, qPCR, mass spectrometry, redox western blot, colony formation, cell proliferation, ROS assay, and immunofluorescence microscopy were used to study the role of NRF-1. RESULTS: The major novel finding of this study is the demonstration of oxidative modification of phosphatases PTEN and CDC25A by E2-generated ROS along with the subsequent activation of AKT and ERK pathways that culminated in the activation of NRF-1 leading to the upregulation of cell cycle genes. 17ß-Oestradiol-induced ROS by influencing nuclear proteins p27 and Jab1 also contributed to the growth of MCF-7 cells. CONCLUSIONS: Taken together, our results present evidence in the support of E2-induced ROS-mediated AKT signalling leading to the activation of NRF-1-regulated cell cycle genes as well as the impairment of p27 activity, which is presumably necessary for the growth of MCF-7 cells. These observations are important because they provide a new paradigm by which oestrogen may contribute to the growth of breast cancer.

Facilitation of lordosis by injection of substance P into the midbrain central gray.

Behavioral experiments tested the idea that the substance P (SP) innervation of the midbrain central gray (MCG) may be involved in the hormonal induction of sexual receptivity in female rats. SP, a SP antiserum or a reported SP antagonist were injected bilaterally into the MCG in ovariectomized, estrogen-treated females, and the lordosis response was recorded at repeated intervals. In the first experiment, three doses of SP (50,500 and 1,000 ng/cannula), a single dose of LHRH (50 ng/cannula) or vehicle were given to separate groups of females. All three doses of SP produced a rapid and long-lasting (3 h) increase in lordosis scores in moderately receptive females in tests with either manual stimulation or male rats. This facilitation was similar in latency, magnitude and duration to that produced by LHRH. In the second experiment, the basic findings of experiment 1 were replicated using blind testing. As no dose-response relation was established in experiment 1, a lower dose of SP (10 ng/cannula) was used in addition to doses of 50 and 500 ng/cannula also used in experiment 1. All three doses produced similar long-lasting increases in lordosis scores as in experiment 1. MCG injections of SP also increased lordosis scores in a second series of tests using manual stimulation alone. This demonstrates that the SP-induced facilitation does not depend on an interaction between the injections and stimuli delivered only by the male rat, eg., vaginal stimuli or ultrasonic calls. The question of the importance of endogenous SP for receptivity was examined in experiment 2 using MCG injections of a SP antiserum or the SP analogue, (D-Pro2, D-Trp7,9)-SP, which has been reported to block the excitation of locus coeruleus neurons by SP.(ABSTRACT TRUNCATED AT 250 WORDS)