Introduction Group Research
Publications Links Contacts
RESEARCH LINES
5. OTHER
GYNAECOLOGICAL DISORDERS
CAPSULE.
Aim of this research line is to unveil the mechanism by which steroid
hormones and endocrine drugs, such as tamoxifen, exert their actions. Understanding
these mechanisms is important to improve drug efficacy, to tailor their use to
responsive patients and to predict side effects of novel drugs.
Estrogens
are natural mitogenic factors in gynaecological tissues and exposure to
exogenous (hormone-replacement-therapy or co-adjuvant breast cancer therapy) or
endogenous estrogens (high BMI, aberrant estrogen signalling or aberrant
expression of steroid converting enzymes) leads to unbalanced growth and to
gynaecological disorders and cancers.
All major actions of estrogens are mediated by estrogen
receptor-alpha (ER-alpha). ER-alpha is a ligand-dependent transcription factor.
Its activity on gene transcription is modulated and fine-tuned by
co-regulators, proteins that bridge (co-activators) or impair (co-repressors)
the ER-alpha /target-promoter complexes with the transcriptional machinery. The
current view suggests that upon binding to Estrogen Response Elements (EREs) or
other motifs in the promoter of target genes, ER-alpha recruits co-regulatory
proteins at target genes and mediates activation of transcription or its
repression. Distinct transcriptional activities on distinct target genes in one
cell type are determined by recruitment of different co-regulators.
Moreover, several
compounds, such as tamoxifen, show anti-estrogenic action in some tissues (like
breast) and at the same time they have estrogenic action in other tissues (such
as the endometrium). These opposite effects are determined by the fact that the
transcription of the same target genes is modulated in opposite directions in
different tissues. These events are also a consequence of the fact that
tamoxifen-bound ER-alpha recruits co-regulators with opposite activities in
different tissues.
For instance, a number
of genes, such as BCL2L1, are modulated in opposite directions in breast
(transcription up-regulation) and endometrial (down-regulation) cell lines.
Tamoxifen-bound ER-alpha recruits co-activators in breast cells leading to
transcription activation, whereas co-repressors are recruited in endometrial
cells with subsequent inhibition of transcription. These transcriptional
effects can be either opposed or inverted by modifying the level of some
co-regulators.
By means of
molecular analyses including cDNA-microarrays and chromatin-immunoprecipitation
/ chip promoter array (ChIP-chip), and by means of bioinformatics tools (in
collaboration with the Department of
Bioinformatics-BiGCaT, Maastricht University), we investigate the mechanism
of action of ER-alpha and the role of co-regulators in determining the tissue-
and the gene-specific responses to estrogens.
These mechanisms are
often the cause of the side effects observed during the use of endocrine drugs,
or are the cause of the resistance of tumours to endocrine drugs. A thorough
understanding of the mechanisms behind these events helps predicting
therapeutic efficacy in patients, tailoring therapies to responsive patients
and predicting side effects of novel drugs.
SELECTED PUBLICATIONS:
Romano A et al. Mol
Cell Endocrinol. 2010 314:10-100.
Punyadeera C et al. J
Steroid Biochem Mol Biol. 2008 112(1-3):102-9.
Groothuis PG et al.
Hum
Reprod Update. 2007 13(4):405-17
Punyadeera C et al. Cell
Mol Life Sci. 2005 62(2):239-50.
Dassen H et al. Cell
Mol Life Sci. 2007 64(7-8):1009-32.
CAPSULE.
Aim of this research line is to examine the local activity of enzymes
converting estrogenic compounds with low potency into compounds with high
estrogenic action. The regulation of these enzymes is frequently un-balanced in
estrogen dependent diseases, leading to overexposure to estrogens.
Understanding the regulation and the aberrations in these metabolic steps leads
to novel target discovery for drugs.
High levels of estrogens and high exposure to these
steroid hormones lead to gynaecological disorders and cancers. In several
cases, however, the level of circulating estrogens in the blood is normal, but
rather the local concentration of these compounds in the target tissues is
altered. Steroid metabolising enzymes are responsible for the tissue
concentration of estrogenic compounds and for their estrogenic potency.
Numerous enzymes are
involved in these metabolisms. Steroid sulphatases activate sulphated compounds
(i.e. inactive) present in the circulation into active compounds whereas
sulpho-transferases catalyse the opposite reaction; 17β-hydroxysteroid-dehydrogenases
convert 17β-estradiol (highly
active estrogen) to estrone (low activity) and vice-versa; aromatases convert
androgens into estrogens.
We analyse the activity
of these enzymes in biopsies from patients or in in vitro models of the human
endometrium using different methodologies. Specifically, we have developed a
HPLC-based method to measure the conversions of steroid hormones. Tissue
lysates are incubated under specific enzymatic conditions to force reactions
towards one direction (for instance estrone - E1 - into 17β-estradiol
- E2 – or vice versa). Purification of estrogens and derivatisation with a
fluorescence compound [2-(4-carboxy-phenyl)-5,6-dimethylbenzimidazole CDB]
allows the easy and non-radioactive detection and quantification of substrate
used and product formed.
We aim at
identifying those metabolic steps that are de-regulated in the diseased tissues
and we aim at developing novel drugs that, by inhibiting the activity of these
steps, may re-establish the correct metabolic balance.
SELECTED PUBLICATIONS:
Delvoux B et al. J
Clin Endocrinol Metab. 2009 94(3):876-83.
Delvoux B et al. J
Steroid Biochem Mol Biol. 2007 104(3-5):246-51.
CAPSULE.
Endometriosis is a multi-factorial disease in which genetic predisposition,
epigenetics, steroid signalling and metabolism, immune response, angiogenesis
and other factors play a role. We use distinct scientific and multi-disciplinary
approaches to address several aspects in the pathogenic mechanism. Final aim is
to improve diagnosis and to improve treatments.
Endometriosis is characterised by the presence of
endometrium outside the uterine cavity (ectopic location). Around 10 % of women
during pre-menopause suffer form endometriosis. Several distressing features
accompany this disease, including pelvic pain, dysmenorrhoea and infertility.
All these have an important impact on the social, professional and marital life
of women suffering from it. Endometriosis is a multi-factorial disorder and
several events are responsible for the translocation of the endometrial tissue
inside the peritoneum, its survival and attachment to the peritoneal cavity and
other locations and for its growth. These include angiogenesis to supply
endometriotic tissue with oxygen and nutrients, estrogen signalling to
stimulate growth, diminished immune surveillance and epigenetic aberrations. In
addition, endometriosis shows familiar clustering, indicating a probable
genetic predisposition in the development of this disorder.
Angiogenesis, estrogen
metabolism, genetic predisposition and epigenetics are all areas of research on
which our group is focussing.
ESTROGEN METABOLISM. By using our HPLC-based method to measure the metabolism of estrogens
in endometriosis patients, we have shown that the equilibrium in the
activation/de-activation of 17β-estradiol in the ectopic location
is shifted towards an increased synthesis and exposure to 17β-estradiol.
GENETIC PREDISPOSITION. Polymorphisms or
variants at genes involved in steroid signalling and immune response have been
investigated for possible association with endometriosis risk. Case control
studies have been performed to assess the influence on endometriosis of the
following variants: PROGINS (Reference SNP Cluster Report: rs1042838)
and +331G/A (rs10895068)
polymorphisms in the progesterone receptor gene; –509C/T polymorphism (rs1800469)
in the transforming Growth Factor β1 gene; –817C>T polymorphism (rs9514828)
in the B lymphocyte stimulator gene.
SELECTED PUBLICATIONS:
de
Graaff A et al. Fertil
Steril, in press.
Delvoux B et al. J
Clin Endocrinol Metab. 2009 94(3):876-83.
van Kaam KJ. Hum
Reprod. 2008 23(12):2692-700.
van Kaam KJ. Reprod
Sci. 2007 May;14(4):367-73.
Romano A. J
Mol Endocrinol. 2007 38(1-2):331-50.
Van Langendonckt A. Mol Hum Reprod. 2007 13(12):875-86
van Kaam KJ. Hum
Reprod. 2007 22(1):129-35.
Endometrial carcinoma is the most
common gynaecological malignancy in developed countries. Most endometrial
tumours are hormone dependent and their growth is sustained by the availability
of estrogens in endometrial cancerous cells. However, endometrial tumours
develop in most cases after menopause, when the ovaries have already ceased
their production of steroid hormones, therefore, the source of estrogens in
endometrial cells may derive from in situ metabolic conversion of other
circulation steroids. One of our important areas of investigation is the
metabolisms of steroid hormones in normal and malignant endometrial tissues to
identify (and subsequently target) those enzymes responsible for the excessive
estrogen concentration in the tissue.
Next
to this, we study additional factors that may be involved in
endometrial carcinogenesis, such as the genetic predisposition and the role
played by epigenetics.
SELECTED PUBLICATIONS:
Romano A. J
Mol Endocrinol. 2007 38(1-2):331-50.
Pijnenborg JM. Ann
Oncol. 2007 18(3):491-7.
Pijnenborg JM. Gynecol
Oncol. 2006 100(2):397-404.
Pijnenborg JM et al. J
Pathol. 2005 205(5):597-605.
5. OTHER
GYNAECOLOGICAL DISORDERS
Our research group also focuses on
the genetic predisposition, the role of estrogens and the epigenetics in
additional estrogen-dependent disorders such as breast and ovarian cancer.
SELECTED PUBLICATIONS:
Romano A. J
Mol Endocrinol. 2007 38(1-2):331-50.
Romano
A. Open Cancer J.
2007; 1:1-8.
Romano A. Gynecol
Oncol. 2006 May;101(2):287-95.