tretinoin and Leiomyomatosis

Uterine fibroids are the most common benign tumour afflicting women of reproductive age. Despite the large healthcare burden caused by fibroids, there is only limited understanding of the molecular mechanisms that drive fibroid pathophysiology. Although a large number of genes are differentially expressed in fibroids compared with myometrium, it is likely that most of these differences are a consequence of the fibroid presence and are not causal. The aim of this study was to investigate the expression and regulation of NR2F2 and CTNNB1 based on their potential causal role in uterine fibroid pathophysiology. We used real-time quantitative RT-PCR, western blotting and immunohistochemistry to describe the expression of NR2F2 and CTNNB1 in matched human uterine fibroid and myometrial tissues. Primary myometrial and fibroid smooth muscle cell cultures were treated with progesterone and/or retinoic acid (RA) and sonic hedgehog (SHH) conditioned media to investigate regulatory pathways for these proteins. We showed that NR2F2 and CTNNB1 are aberrantly expressed in fibroid tissue compared with matched myometrium, with strong blood vessel-specific localisation. Although the SHH pathway was shown to be active in myometrial and fibroid primary cultures, it did not regulate NR2F2 or CTNNB1 mRNA expression. However, progesterone and RA combined regulated NR2F2 mRNA, but not CTNNB1, in myometrial but not fibroid primary cultures. In conclusion, we demonstrate aberrant expression and regulation of NR2F2 and CTNNB1 in uterine fibroids compared with normal myometrium, consistent with the hypothesis that these factors may play a causal role uterine fibroid development.

Topics: Adult; beta Catenin; Blood Vessels; Cells, Cultured; COUP Transcription Factor II; Female; Follicular Phase; Gene Expression Regulation, Neoplastic; Hedgehog Proteins; Humans; Leiomyomatosis; Luteal Phase; Middle Aged; Myometrium; Neoplasm Proteins; Peptide Fragments; Progesterone; Protein Structure, Tertiary; Recombinant Proteins; Tretinoin; Tumor Cells, Cultured; Uterine Neoplasms

Uterine leiomyomata are the main indication for a hysterectomy in the United States and occur in 25% of women >35 years. Because uterine leiomyomata can form when ovariectomized guinea pigs are exposed to estradiol and retinoic acids, we tested whether human leiomyomata had high levels of retinoic acids and related nuclear receptors. Compared with normal human myometrium, leiomyomata had 3- to 5-fold higher levels of peroxisome proliferator-activated receptor gamma (PPARgamma), retinoid X receptor alpha proteins, and all-trans retinoic acid, but only during the follicular phase of the menstrual cycle. 9-cis Retinoic acid was undetectable in either leiomyomata or myometrium. PPARgamma mRNA levels were lower in leiomyomata than myometrium, but only during the luteal phase of the cycle. A PPARgamma agonist, troglitazone, was given to guinea pigs along with estradiol and all-trans retinoic acid and produced the largest leiomyomata seen to date in this model. By contrast, no tumors formed when troglitazone was given alone or with estradiol or when troglitazone was given with estradiol and 9-cis retinoic acid. New therapies for human leiomyomata may emerge by combining antagonists for PPARgamma and retinoid X receptor alpha with selective estrogen receptor modulators.

Topics: Alitretinoin; Animals; Carcinogens; Chromans; Drug Implants; Estradiol; Female; Guinea Pigs; Humans; Leiomyomatosis; Menstrual Cycle; Myometrium; Neoplasm Proteins; Receptors, Cytoplasmic and Nuclear; Receptors, Retinoic Acid; Retinoic Acid Receptor alpha; Thiazoles; Thiazolidinediones; Transcription Factors; Tretinoin; Troglitazone; Uterine Neoplasms