Induction of the angiogenic factor VEGF in the uterus by the antiprogestin onapristone

Associations of pregnancy characteristics with maternal and cord steroid hormones, angiogenic factors, and insulin-like growth factor axis

BACKGROUND

The objective of this study was to comprehensively profile biological factors in pregnancy that have been postulated to be important components of the in utero environment and may also have relevance to later susceptibility to cancer and other chronic diseases.

METHODS

Steroid sex hormones, IGFs, and angiogenic factors were measured in maternal and cord serum from term normotensive pregnancies. Spearman correlations and linear regression estimated relationships among the biological factors and clinical characteristics.

RESULTS

The analytes were generally not correlated between maternal and fetal circulations. However, significant correlations were demonstrated among several analytes within maternal or cord samples. A few analytes were associated with clinical characteristics (e.g., maternal IGF-1 and IGFBP-3 were inversely correlated with offspring birth weight, while maternal leptin and cord testosterone were positively correlated with this characteristic). Maternal androgens were higher in African-Americans than whites, and maternal PlGF and soluble fms-like tyrosine kinase-1 (sFlt-1) were higher in male than female offspring.

CONCLUSIONS

There were significant correlations among analytes, but the patterns differed depending on whether they were measured in the maternal or fetal circulation. The number and magnitude of correlations among analytes, however, should affect the design and interpretation of future studies.

Inhibition of vascular endothelial growth factor receptor signal transduction blocks follicle progression but does not necessarily disrupt vascular development in perinatal rat ovaries

We hypothesized that vascular endothelial growth factor A (VEGFA) angiogenic isoforms and their receptors, FLT1 and KDR, regulate follicular progression in the perinatal rat ovary. Each VEGFA angiogenic isoform has unique functions (based on its exons) that affect diffusibility, cell migration, branching, and development of large vessels. The Vegfa angiogenic isoforms (Vegfa_120, Vegfa_164, and Vegfa_188) were detected in developing rat ovaries, and quantitative RT-PCR determined that Vegfa_120 and Vegfa_164 mRNA was more abundant after birth, while Vegfa_188 mRNA was highest at Embryonic Day 16. VEGFA and its receptors were localized to pregranulosa and granulosa cells of all follicle stages and to theca cells of advanced-stage follicles. To determine the role of VEGFA in developing ovaries, Postnatal Day 3/4 rat ovaries were cultured with 8 muM VEGFR-TKI, a tyrosine kinase inhibitor that blocks FLT1 and KDR. Ovaries treated with VEGFR-TKI had vascular development reduced by 94% (P < 0.0001), with more primordial follicles (stage 0), fewer early primary, transitional, and secondary follicles (stages 1, 3, and 4, respectively), and greater total follicle numbers compared with control ovaries (P < 0.005). V1, an inhibitor specific for KDR, was utilized to determine the effects of only KDR inhibition. Treatment with 30 muM V1 had no effect on vascular density; however, treated ovaries had fewer early primary, transitional, and secondary follicles and more primary follicles (stage 2) compared with control ovaries (P < 0.05). We conclude that VEGFA may be involved in primordial follicle activation and in follicle maturation and survival, which are regulated through vascular-dependent and vascular-independent mechanisms.

Antisense oligonucleotides targeting the progesterone receptor inhibit hormone-independent breast cancer growth in mice

Introduction

Previous data from our laboratory suggested that progesterone receptors (PRs) are involved in progestin-independent growth of mammary carcinomas. To investigate this possibility further, we studied the effects of PR antisense oligodeoxynucleotides (asPR) on in vivo tumor growth.

Method

BALB/c mice with subcutaneous 25 mm² mammary carcinomas expressing estrogen receptor-α and PR were either injected intraperitoneally with 1 mg asPR every 24 or 12 hours for 5–10 days, or subcutaneously with RU 486 (6.5 mg/kg body weight) every 24 hours. Control mice received vehicle or scPR.

Results

Significant inhibition of tumor growth as well as a significant decrease in bromodeoxyuridine uptake was observed in asPR-treated mice, which correlated with histological signs of regression and increased apoptosis. Mice treated with RU 486 experienced almost complete tumor regression. No differences were detected between vehicle-treated and scPR-treated mice. Anti-progestin-treated and asPR-treated mice were in a continuous estrous/meta-estrous state. Decreased phosphorylated extracellular signal-regulated kinase (ERK)1 and ERK2 levels and estrogen receptor-α expression were observed as late events in RU 486-treated and asPR-treated mice with regressing tumors.

Conclusion

We demonstrate, for the first time, inhibition of tumor growth in vivo using asPR. Our results provide further evidence for a critical and hierarchical role of the PR pathway in mammary carcinomas.

Proliferation of endothelial and tumor epithelial cells by progestin-induced vascular endothelial growth factor from human breast cancer cells: paracrine and autocrine effects

Angiogenesis, the formation of new blood vessels, is essential for tumor expansion, and vascular endothelial growth factor (VEGF) is one of the most potent angiogenic growth factors known. We have previously shown that natural and synthetic progestins, including those used in hormone replacement therapy and oral contraception, induce the synthesis and secretion of VEGF in a subset of human breast cancer cells in a progesterone receptor-dependent manner. We now report that conditioned medium from progestin-treated breast tumor cells can induce the proliferation of endothelial cells in a paracrine manner and induce the proliferation of tumor epithelial cells in a paracrine and an autocrine manner. The use of an anti-VEGF antibody and SU-1498, an inhibitor of VEGF receptor-2 (VEGFR-2 or flk/kdr) tyrosine kinase activity, demonstrated that these effects involve interactions between VEGF and VEGFR-2. Also, blockage of progestin-induced VEGF by the antiprogestin RU-486 (mifepristone) eliminated VEGF-induced proliferative effects. The ability of VEGF to increase the proliferation of endothelial cells and tumor cells, including those that do not release VEGF in response to progestins, suggests that these effects are mediated by amplification of the progestin signal, which culminates in angiogenesis and tumor growth. These novel findings suggest that targeting the release of VEGF from tumor epithelial cells as well as blocking interactions between VEGF and VEGFR-2 on both endothelial and tumor epithelial cells may facilitate the development of new antiangiogenic therapies for progestin-dependent breast tumors. Furthermore, these data indicate that it would be useful to develop selective progesterone receptor modulators that prevent the release of angiogenic growth factors from breast cancer cells.

Modulation of nerve growth factor in peripheral organs by estrogen and progesterone

Nerve growth factor (NGF) synthesized in peripheral organs plays a critical role in the development and maintenance of the nervous system and also participates in processing nociceptive stimuli. Previous studies suggest that reproductive hormones may regulate the expression of NGF. Ovariectomies were performed on female mice, and mice were killed 24 h after hormone replacement to evaluate the effects of estrogen and progesterone on NGF in peripheral organs, specifically the uterus, bladder, heart, and salivary gland. Sham-operated intact mice and untreated ovariectomized mice served as controls. Immunohistochemistry demonstrated the presence of NGF, estrogen receptor-alpha, estrogen receptor-beta, and progesterone receptors in these organs. Ovariectomy caused a significant decrease in NGF protein content in the uterus, and short term treatment of ovariectomized mice with estrogen and/or progesterone increased uterine NGF mRNA and restored NGF protein to concentrations similar to intact control mice. Ovariectomy did not affect NGF protein concentrations in the salivary gland, but treatment of ovariectomized mice with estrogen alone or in conjunction with progesterone stimulated concentrations of NGF protein that exceeded those observed in intact control or ovariectomized, untreated mice. NGF mRNA was increased in salivary glands from ovariectomized mice treated with progesterone alone or in combination with estrogen relative to other groups. NGF protein content of the hearts of ovariectomized mice treated with estrogen alone or in conjunction with progesterone was increased relative to intact controls and ovariectomized, untreated mice, but neither ovariectomy or hormone replacement affected NGF mRNA content in the heart. NGF protein content of the bladder was unaffected by ovariectomy or hormone treatment, and bladder NGF mRNA was unaffected by ovariectomy or hormone treatment. Collectively, these results indicate that reproductive hormones have the capacity to regulate NGF message and protein in a manner that varies among organs. Fluctuations in the expression of NGF, in conjunction with other factors, may help to explain gender differences in pain sensation and inflammatory response.