Progestins suppress estrogen-induced expression of vascular endothelial growth factor (VEGF) subtypes in uterine endometrial cancer cells

Progestin Resistance and Corresponding Management of Abnormal Endometrial Hyperplasia and Endometrial Carcinoma

With a younger tendency in morbidity age, endometrial cancer (EC) incidence has grown year after year. Worse, even more commonly occurring is endometrial hyperplasia (EH), which is a precancerous endometrial proliferation. For young women with early EC and EH who want to preserve fertility, progestin therapy has been utilized as a routine fertility-preserving treatment approach. Nevertheless, progestin medication failure in some patients is mostly due to progestin resistance and side effects. In order to further analyze the potential mechanisms of progestin resistance in EH and EC, to provide theoretical support for effective therapeutic strategies, and to lay the groundwork for searching novel treatment approaches, this article reviews the current therapeutic effects of progestin in EH and EC, as well as the mechanisms and molecular biomarkers of progestin resistance, and systematically expounds on the potential therapeutic methods to overcome progestin resistance.

Solving the Puzzle: What Is the Role of Progestogens in Neovascularization?

Ovarian sex steroids can modulate new vessel formation and development, and the clarification of the underlying mechanism will provide insight into neovascularization-related physiological changes and pathological conditions. Unlike estrogen, which mainly promotes neovascularization through activating classic post-receptor signaling pathways, progesterone (P4) regulates a variety of downstream factors with angiogenic or antiangiogenic effects, exerting various influences on neovascularization. Furthermore, diverse progestins, the synthetic progesterone receptor (PR) agonists structurally related to P4, have been used in numerous studies, which could contribute to unequal actions. As a result, there have been many conflicting observations in the past, making it difficult for researchers to define the exact role of progestogens (PR agonists including naturally occurring P4 and synthetic progestins). This review summarizes available evidence for progestogen-mediated neovascularization under physiological and pathological circumstances, and attempts to elaborate their functional characteristics and regulatory patterns from a comprehensive perspective.

Sex steroids influence organizational but not functional decidualization of feline endometrial cells in a 3D culture system†

Successful implantation requires complex signaling between the uterine endometrium and the blastocyst. Prior to the blastocyst reaching the uterus, the endometrium is remodeled by sex steroids and other signals to render the endometrium receptive. In vitro models have facilitated major advances in our understanding of endometrium preparation and endometrial-blastocyst communication in mice and humans, but these systems have not been widely adapted for use in other models which might generate a deeper understanding of these processes. The objective of our study was to use a recently developed, three-dimensional culture system to identify specific roles of female sex steroids in remodeling the organization and function of feline endometrial cells. We treated endometrial cells with physiologically relevant concentrations of estradiol and progesterone, either in isolation or in combination, for 1 week. We then examined size and density of three-dimensional structures, and quantified expression of candidate genes known to vary in response to sex steroid treatments and that have functional relevance to the decidualization process. Combined sex steroid treatments recapitulated organizational patterns seen in vivo; however, sex steroid manipulations did not induce expected changes to expression of decidualization-related genes. Our results demonstrate that sex steroids may not be sufficient for complete decidualization and preparation of the feline endometrium, thereby highlighting key areas of opportunity for further study and suggesting some unique functions of felid uterine tissues.

Sex steroids in uterine endometrial cancers

Some uterine endometrial cancers conserve estrogen dependency in advancement. However, the concept of advancement in tumor is complicated, because it involves simple growth in primary tumor and secondary spreading. The expression manner of estrogen receptor alpha exon 5 splicing variant, ER beta, progesterone receptor-A (N-terminus deletion mutant) is associated with metastatic potential in uterine endometrial cancers. Increased estrogen-related receptor alpha expression is related to tumor advancement with the loss of estrogen dependency. Steroid receptor coactivator-3 contributes to tumor progression and can be used as a treatment target for advanced uterine endometrial cancers. Estrogen responsive oncogenes, c-jun and c-Ha-ras, are not modi-fied by progestin in uterine endometrial cancer cells and are considered to be an instinct phenotype as such cancers. By contrast, metastatic potential of estrogen-dependent uterine endometrial cancers can be partially controlled by progestin via metastasis-related genes, E-cadherin/catenins, plasminogen activator inhibitor-1, vascular endothelial growth factor. Thus, sex steroids related phenomena are impress-ive in the advancement of uterine endometrial cancers.

Effects of natural and recombinant hirudin on VEGF expression and random skin flap survival in a venous congested rat model

We aim to investigate the effects of locally injected natural and recombinant hirudin on vascular endothelial growth factor (VEGF) expression and flap survival in venous congested skin flaps using a rat model. A dorsal random skin flap (10 × 3 cm) was prepared on each of 30 Wistar rats to establish a venous congested model. The rats were randomly divided into 2 treatment groups [receiving subcutaneous injection of either natural hirudin (6 U) or recombinant hirudin (6 U)] and a control group, which received subcutaneous injection of physiologic saline. After treatment, skin flap survival rates were calculated. VEGF messenger RNA levels and VEGF-positive vessel density as a marker for VEGF levels were measured in the flaps during and after treatment. The skin flap VEGF messenger RNA levels increased in the natural hirudin-treated group. The VEGF-positive vessel density was increased in all 3 groups. Statistically significant increases of VEGF levels were observed in the natural and recombinant hirudin-treated groups compared with the control group (P < 0.05). The skin flap survival rates were improved in both hirudin treated groups. Natural and recombinant hirudin can increase VEGF expression in random skin flaps, which can potentially improve random skin flap survival in rats through angio genic mechanisms. Our results showed that hirudin treatment led to an increase in VEGF expression in the congested skin flaps. Natural hirudin demonstrated more pronounced effects than recombinant hirudin. Further studies are needed to understand the specific mechanisms.

Effects of estrogen replacement therapy on apoptosis and vascular endothelial growth factor expression in ocular surface epithelial cells: An experimental study

AIM

To investigate the effects of estrogen replacement therapy (ERT) on apoptosis and vascular endothelial growth factor (VEGF) expression in ocular surface in an experimental rat model.

METHODS

Forty female, Wistar rats were randomized in 4 groups in the study. Subcutaneous ERT (17β-estradiol, 10µg/kg/day) was administered to the first group without ovariectomy and to the second group with ovariectomy for three months. Third group had only ovariectomy and fourth group had sham operation. All rats were sacrificed in estrous cycles determined by vaginal smear test and their right eyes were enucleated at the end of the third month. Enucleated eyes were analyzed by immunohistochemical method for expressions of caspase-3, bcl-2, VEGF and TUNEL assay.

RESULTS

Caspase-3 expression of conjunctival epithelium was significantly higher in group 3 than group 1 (P=0.005), and group 2 (P=0.007). TUNEL score of conjunctival epithelium was significantly higher in group 3 than group1 (P=0.006). TUNEL score of corneal epithelium was significantly higher in group 3 than group 2 (P=0.012), and group 4 (P=0.002). There was no significant difference between groups in that bcl-2 and VEGF expressions.

CONCLUSION

We determined increased apoptosis in ocular surface epithelial cells in ovariectomized rats. ERT and endogen estrogen decreased the apoptosis, and did not result in difference in VEGF expression between the groups. Estrogen may be beneficial for the treatment of apoptosis-mediated ocular surface disorders such as dry eye. Further studies are needed on this subject for a better understanding of the role of estrogen and to provide a new insight for treatment and prevention of apoptosis-mediated ocular surface disorders.

Does hormone therapy, tibolone or raloxifene modify VEGF expression in cervical epithelial cells?

AIM

Vascular endothelial growth factor (VEGF) seems to be a critical molecule in cervical carcinogenesis. We aimed to investigate the possible associations between hormonal factors and VEGF expression in cervical epithelial cells from postmenopausal women.

METHOD

A total of 105 healthy postmenopausal women (aged 45-68 years old) attending a university menopause clinic were enrolled in this cross-sectional study. Pap smears were derived from current users of 17β-estradiol 1 mg + norethisterone acetate 0.5 mg (n = 28), tibolone 2.5 mg (n = 23), raloxifene HCl 60 mg (n = 21) and women not receiving treatment (n = 33). VEGF immunostaining was evaluated in squamous, glandular and metaplastic cells, using a semiquantitative method (rating scale: 0-3).

RESULTS

Concerning endogenous hormones, higher Δ4-androstenedione levels were associated with more intense VEGF immunostaining in glandular (p = 0.041) and metaplastic cells (p = 0.004). Hormone therapy and raloxifene did not induce any changes in VEGF immunoreactivity in the examined cells. In contrast, tibolone administration was accompanied by diminished VEGF presence in metaplastic cells (p = 0.016 vs. controls).

CONCLUSION

Our findings may in part reflect the molecular processes contributing to the safe profile of hormone therapy, tibolone and raloxifene in cervical carcinogenesis.

Immunohistochemical expression of basic fibroblast growth factor and fibroblast growth factor receptors 1 and 2 in the pathogenesis of lung cancer

PURPOSE

To identify the patterns of protein expression of basic fibroblast growth factor (bFGF) and FGF receptors 1 and 2 in non-small cell lung carcinoma (NSCLC) and their role in the early pathogenesis of squamous cell carcinoma (SCC) of the lung.

EXPERIMENTAL DESIGN

Archived tissue from NSCLC (adenocarcinoma and SCC; n = 321) and adjacent bronchial epithelial specimens (n = 426) were analyzed for the immunohistochemical expression of bFGF, FGFR1, and FGFR2, and the findings were correlated with clinicopathologic features of the patients.

RESULTS

High expression of bFGF, FGFR1, and FGFR2 was shown in most NSCLC tumors. The pattern of expression for all markers varied according to tumor histologic type and cellular localization. Cytoplasmic expression scores were significantly higher in tumors than in normal epithelia. Nuclear bFGF (P = 0.03) and FGFR1 (P = 0.02) levels were significantly higher in women than in men. Although cytoplasmic FGFR1 expression was significantly higher (P = 0.002) in ever smokers than in never smokers, nuclear FGFR1 (P = 0.0001) and FGFR2 (P = 0.003) expression was significantly higher in never smokers. Different prognostic patterns for the expression of these markers were detected for both NSCLC histologic types. Dysplastic changes showed significantly higher expression of all markers compared with squamous metaplasia.

CONCLUSIONS

bFGF, FGFR1, and FGFR2 are frequently overexpressed in SCC and adenocarcinoma of the lung. bFGF signaling pathway activation may be an early phenomenon in the pathogenesis of SCC and thus an attractive novel target for lung cancer chemopreventive and therapeutic strategies.

VEGF/VEGFR signalling as a target for inhibiting angiogenesis

VEGFs and a respective family of tyrosine kinases receptors (VEGFRs) are key proteins modulating angiogenesis, the formation of new vasculature from an existing vascular network. There has been considerable evidence in vivo, including clinical observations, that abnormal angiogenesis is implicated in a number of disease conditions, which include rheumatoid arthritis, inflammation, cancer, psoriasis, degenerative eye conditions and others. Antiangiogenic therapies based on inhibition of VEGF/VEGFR signalling were reported to be powerful clinical strategies in oncology and ophthalmology. Current efforts have yielded promising clinical data for several antiangiogenic therapeutics. In this review, the authors elucidate key aspects of VEGFR signalling, as well as clinically relevant strategies for the inhibition of VEGF-induced angiogenesis, with an emphasis on small-molecule VEGFR inhibitors.

Estrogen Receptors α and β Mediate Contribution of Bone Marrow–Derived Endothelial Progenitor Cells to Functional Recovery After Myocardial Infarction

Background— Estradiol (E 2 ) modulates the kinetics of circulating endothelial progenitor cells (EPCs) and favorably affects neovascularization after ischemic injury. However, the roles of estrogen receptors α (ERα) and β (ERβ) in EPC biology are largely unknown.

Methods and Results— In response to E 2 , migration, tube formation, adhesion, and estrogen-responsive element–dependent gene transcription activities were severely impaired in EPCs obtained from ERα-knockout mice (ERαKO) and moderately impaired in ERβKO EPCs. The number of ERαΚΟ EPCs (42.4±1.5; P <0.001) and ERβKO EPCs (55.4±1.8; P =0.03) incorporated into the ischemic border zone was reduced as compared with wild-type (WT) EPCs (72.5±1.3). In bone marrow transplantation (BMT) models, the number of mobilized endogenous EPCs in E 2 -treated mice was significantly reduced in ERαKO BMT (WT mice transplanted with ERαKO bone marrow) (2.03±0.18%; P =0.004 versus WT BMT) and ERβKO BMT (2.62±0.07%; P =0.02 versus WT) compared with WT BMT (2.87±0.13%) (WT to WT BMT as control) mice. Capillary density at the border zone of ischemic myocardium also was significantly reduced in ERαKO BMT and ERβKO BMT compared with WT mice (WT BMT, 1718±75/mm 2 ; ERαKO BMT, 1107±48/mm 2 ; ERβKO BMT, 1567±50/mm 2 ). ERα mRNA was expressed more abundantly on EPCs compared with ERβ. Moreover, vascular endothelial growth factor was significantly downregulated on ERαKO EPCs compared with WT EPCs both in vitro and in vivo.

Conclusions— Both ERα and ERβ contribute to E 2 -mediated EPC activation and tissue incorporation and to preservation of cardiac function after myocardial infarction. ERα plays a more prominent role in this process. Moreover, ERα contributes to upregulation of vascular endothelial growth factor, revealing possible mechanisms of an effect of E 2 on EPC biology. Finally, these data provide additional evidence of the importance of bone marrow–derived EPC phenotype in ischemic tissue repair.

VEGF and its receptors (flt-1 and KDR/flk-1) as prognostic indicators in endometrial carcinoma

Vascular endothelial growth factor (VEGF) is associated with increased angiogenesis and aggressive tumour growth. We investigated the expression and clinical significance of VEGF and its receptors, flt-1 and KDR/flk-1, in patients with uterine endometrial carcinoma. The series consisted of 115 endometrioid endometrial adenocarcinoma patients with FIGO stage I-IV. Additionally, samples from 3 patients with adenoacanthoma and 12 patients with poor prognostic variants of endometrial carcinoma were examined. Immunohistochemical assessment was classified as negative or positive based on staining intensity. The median follow-up time of patients with endometrioid endometrial adenocarcinoma was 87 months. In endometrioid endometrial carcinomas, the positive immunostaining rate was 39% for VEGF, 65% for flt-1 and 68% for KDR/flk-1. There was a significant correlation between VEGF and both its receptors. Furthermore, this receptor expression was correlated between the two types of receptors. VEGF-, flt-1- and KDR/flk-1-positive immunostainings were not related to poor prognosis. We conclude that VEGF, flt-1 and KDR/flk-1 expressions are not useful prognostic markers for overall survival in patients with endometrioid endometrial carcinoma.

Sex steroid-dependent angiogenesis in uterine endometrial cancers

In general, tumors induce angiogenic factors specific to them, which leads to angiogenesis with advancement. However, angiogenesis in uterine endometrial cancers is complicated because hormone dependency in growth also modifies the angiogenic potential. Therefore, anti-angiogenic therapy for tumor dormancy in uterine endometrial cancers must be thoroughly considered. The upstream of vascular endothelial growth factor (VEGF) gene conserves estrogen-responsive elements. Progesterone primed with estrogen induces thymidine phosphorylase (TP) in uterine endometrium. Sex steroid-dependent VEGF and TP are highly expressed in cases of early stage and well-differentiated uterine endometrial cancers, and basic fibroblast growth factor (bFGF) in cases of advanced and poorly differentiated uterine endometrial cancers. A transcriptional factor for angiogenesis, ETS-1, is linked to VEGF in well-differentiated uterine endometrial cancers, and to bFGF in poorly differentiated uterine endometrial cancers. Therefore, even if dedifferentiation and angiogenic switching occur due to advancement and long-term hormone therapy, the inhibition of ETS-1 along with main angiogenic factors might be an effective strategy to suppress uterine endometrial cancers as a novel anti-angiogenic therapy.

Clinical implications of expression of cyclooxygenase-2 related to angiogenesis in uterine endometrial cancers

BACKGROUND

Angiogenesis is essential for development, growth and advancement of solid tumors. Cyclooxygenase (cox)-2 is recognized as an angiogenic factor in various tumors. This prompted us to study the clinical implications of cox-2 expression and angiogenesis in uterine endometrial cancers.

PATIENTS AND METHODS

Fifty patients underwent curative resection for uterine endometrial cancers. In uterine endometrial cancers, cox-2 levels were determined by enzyme immunoassay, and the localization and counts of microvessels were determined by immunohistochemistry.

RESULTS

There was a significant correlation between microvessel counts and cox-2 levels in uterine endometrial cancers. Cox-2 localized in the cancer cells, but not in the stromal cells of uterine endometrial cancer tissues. Cox-2 levels decreased with the advancement. Furthermore, cox-2 levels significantly correlated with VEGF levels in uterine endometrial cancers.

CONCLUSIONS

VEGF associated with cox-2 might work on angiogenesis at an early status in growth. Therefore, long-term administration of cox-2 inhibitors might be effective in the suppression of recurrent initiation of uterine endometrial cancers after curative resection.

Progestins activate vascular endothelial growth factor gene transcription in endometrial adenocarcinoma cells

OBJECTIVE

To determine whether progestins activate vascular endothelial growth factor (VEGF) gene transcription in endometrial adenocarcinoma cells.

DESIGN

In vitro study.

SETTING

University reproductive biology laboratories.

PATIENT(S)

None.

INTERVENTION(S)

Ishikawa cells were transfected with VEGF promoter-luciferase reporter constructs and expression vectors encoding human progesterone receptors (hPR) A or B. The cells were treated with different progestins and antiprogestins, and luciferase activity was compared with controls.

MAIN OUTCOME MEASURE(S)

Three functional progesterone response elements (PREs) in the VEGF promoter were identified by electrophoretic mobility-shift assay, and different constructs were created to assess each PRE.

RESULT(S)

In cells expressing hPRA or B, treatment with 10 nM R5020 or 100 nM medroxyprogesterone acetate statistically significantly increased luciferase activity (3.3- to 4.8-fold). Pretreatment with 100 nM RU486 blunted the effect of 10 nM R5020, resulting only in a slight, statistically nonsignificant increase in luciferase activity (1.3- to 1.7-fold). Although three different functional PREs could be identified, no single PRE accounted for the preponderance of the luciferase activity. Full VEGF promoter activation required all three PREs.

CONCLUSION(S)

Progestins have a direct effect on VEGF gene transcription. However, hPR-mediated transcriptional regulation of the VEGF promoter is complex and cannot be localized to confined PRE sequences. Other response element motifs are likely to play a contributory role.

Clinical implications of expression of ETS-1 related to angiogenesis in uterine endometrial cancers

BACKGROUND

Angiogenesis is essential for development, growth and advancement of solid tumors. During angiogenesis, ETS-1 is strongly expressed in vascular endothelial cells and the adjacent interstitial cells, while the inhibition of ETS-1 expression leads to suppression of angiogenesis. This prompted us to study the clinical implications of ETS-1 in relation to angiogenesis in uterine endometrial cancers.

PATIENTS AND METHODS

Sixty patients underwent resection for uterine endometrial cancers. From the tissues of 60 uterine endometrial cancers, the levels of ets-1 mRNA, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), platelet-derived endothelial cell growth factor (PD-ECGF) and interleukin (IL)-8 were determined by competitive RT-PCR using recombinant RNA and enzyme immunoassay, and the localization and counts of microvessel were determined by immunohistochemistry.

RESULTS

There was a significant correlation between microvessel count and ets-1 gene expression levels in uterine endometrial cancers. Immunohistochemical staining revealed that the localization of ETS-1 was similar to that of vascular endothelial cells. The level of ets-1 mRNA tended to increase with increasing disease stage. Furthermore, the level of ets-1 mRNA correlated with levels of VEGF in well-differentiated adenocarcinomas (G1) and of bFGF in moderately differentiated adenocarcinomas (G2) and poorly differentiated adenocarcinomas (G3).

CONCLUSIONS

ETS-1 is a possible angiogenic mediator in uterine endometrial cancers.

Hormonal treatment of endometrial carcinoma

Endometrial cancer has typically been regarded as a relatively benign disease. However, survival rates for patients with advanced-stage or recurrent disease are very poor and more adequate systemic treatment is certainly needed. Being a tumor that arises from a hormone responsive tissue, endometrial cancer is a logical target for endocrine manipulation. This article gives an overview of our current knowledge on hormonal therapy and highlights the large potential for improvement in results of such therapy. Target areas for future research are described.

Natural modulators of estrogen biosynthesis and function as chemopreventive agents

There is clearly a need for novel breast cancer chemopreventive agents with enhanced potency and specificity with little or no side effects. To this end, several new chemical moieties have been synthesized or isolated from natural sources. In this review, we have described some agents currently in use or under development for treatment or prevention of breast cancer, as well as our own strategies for the discovery of natural product modulators of estrogen biosynthesis and function. In particular, bioassay-guided fractionation of active plant extracts is a unique method for identifying agents with novel mechanisms of action, some of which should be useful for prevention of human cancer. Further, with the advent of combinatorial chemistry and high throughput screening, even greater progress may now be expected with natural product leads.

Clinical implications of expression of vascular endothelial growth factor in metastatic lesions of ovarian cancers

Vascular endothelial growth factor (VEGF) has been identified as an important factor for tumour angiogenesis, which is essential for the growth, invasion and metastasis of solid tumours. Significantly increased VEGF level from the primary tumour to the metastatic lesion of ovarian cancers was found in 8 of 30 cases. The 24-month survival rate of the patients with significantly increased VEGF level was extremely poor (0/8 = 0%) in comparison with that of patients with no change in the level (15/22 = 68%) from the primary tumour to the metastatic lesion. This indicates that VEGF may contribute to the advancement of metastatic lesions, and that VEGF level in metastatic lesions may be a prognostic indicator.

Postmenopausal oestrogen replacement therapy and atherosclerosis: can current compounds provide cardiovascular protection?

The natural oestrogen, 17 beta-oestradiol, has been implicated in protection from atherosclerosis, a chronic systemic vascular disease with an inflammatory component accounting for the majority of morbidity and mortality in Western countries. Despite the protective effects of 17 beta-oestradiol in premenopausal women and experimental evidence demonstrating inhibitory effects of oestrogen on atherosclerosis progression, it is currently unclear whether hormone replacement therapy can affect cardiovascular morbidity and mortality in postmenopausal women. The recent advances in understanding the mechanisms of oestrogen action demonstrated roles for different oestrogen receptors and oestrogen metabolites in the pathogenesis of vascular injury and endothelial cell dysfunction. However, their respective role in the process of atherogenesis remains yet to be elucidated. Moreover, the availability of novel drugs with tissue- and/or receptor-specific actions will help to understand the role of oestrogen in cardiovascular diseases. Several ongoing large-scale clinical trials using opposed or unopposed replacement therapy with natural or synthetic oestrogens, or selective oestrogen receptor modulators (SERMs) will resolve the question whether the drugs currently available have therapeutic potential to interfere with the progression of atherosclerosis and its complications.

Steroid receptors and metastatic potential in endometrial cancers

The relative overexpression of estrogen receptor (ER)-alpha exon 5 splicing variant, the disrupted synchronization of ER-beta and ER-alpha expressions, and the suppression of progesterone receptor (PR) form A expression as a transcriptional repressor might be related to metastatic potential of uterine endometrial cancers, leading to poor patient prognosis related to estrogen refractoriness.

Progestins suppress estrogen-induced expression of vascular endothelial growth factor (VEGF) subtypes in uterine endometrial cancer cells

Vascular endothelial growth factor (VEGF) contributes to the early advancement of uterine endometrial cancers that conserve hormone dependency via angiogenic activity. This process prompted us to study sex steroidal suppression of VEGF expression in Ishikawa cells (a line of well-differentiated uterine endometrial cancer cells). Estrogen transiently induced VEGF subtype (VEGF165 and VEGF121) secretion from Ishikawa cells. Progestins (progesterone, medroxyprogesterone acetate (MPA) and 17 alpha-hydroxyprogesterone) suppressed the estrogen-induced events. In conclusion, progestins could suppress VEGF-related angiogenic potential, which contributes to tumor growth in the early stage of uterine endometrial cancers that conserve estrogen dependency.