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-Subunit Promoter/Simian Virus 40 T-Antigen Fusion Gene
Department of Physiology University of Turku 20520 Turku, Finland
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
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-subunit promoter (inhp), develop gonadal tumors of
granulosa/theca or Leydig cell origin. We showed previously that
adrenocortical tumors develop if the TG mice are gonadectomized but
never develop in intact animals. However, if functional gonadectomy was
induced by GnRH antagonist treatment or by cross-breeding the TG mice
into the hypogonadotropic hpg genetic background,
neither gonadal nor adrenal tumors appeared. Since the most obvious
difference between the gonadectomized and GnRH-antagonist-treated or
Tag/hpg double mutant mice is the elevated
gonadotropin secretion in the first group, we examined whether the
adrenal tumorigenesis would be gonadotropin-dependent. Surprisingly,
both the adrenal tumors and a cell line (C1) derived from one of
them expressed highly functional LH receptors (LHR), as assessed by
Northern hybridization, immunocytochemistry, ligand binding, and human
CG (hCG)-stimulated cAMP and steroid production. No FSH receptor
expression was found in the adrenal tumors by RT-PCR. hCG treatment of
the C1 cells stimulated their proliferation, as measured by
[3H]thymidine incorporation. This
effect was related to hCG-stimulated steroidogenesis since
progesterone, testosterone, and estradiol, at physiological
concentrations, also stimulated the C1 cell proliferation. Different
adrenocortical cells expressed initially LHR and Tag, whereas both were
highly expressed in the tumor cells. In conclusion, the high level of
functional LHR in the adrenal tumors indicates that this receptor can
function as tumor promoter when ectopically expressed and stimulated by
the ligand hormone. |
INTRODUCTION |
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TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
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p fused with the
Tag coding sequences (1, 2, 3). The gonadal tumors, originating from
granulosa/theca or Leydig cells, appear in two established TG mouse
lines (IT6-M and IT6-F) with 100% penetrance by the age of 5–8
months. The tumor growth was clearly gonadotropin-dependent (4), in
which sense our model resembles the inhibin- knock-out mice, which
also develop gonadotropin-dependent gonadal tumors (5, 6, 7). TG mice
gonadectomized before puberty developed adrenal gland tumors, which was
never detected in intact TG mice, suggesting that some gonadal or
gonad-dependent factors inhibit the adrenal tumorigenesis in the intact
TG mice (3).
The adrenal expression of the endogenous inhibin- and transgenic Tag
genes were found to be suppressed by inhibin, when tested in cell lines
derived from the TG tumors (3). This finding indicated a novel
autoregulatory mechanism of inhibin gene expression in the mouse
adrenal gland and is in line with its tumor suppressor role as
established in inhibin-deficient knock-out mice (5). Since the gonadal
tumors produced high concentrations of inhibin, we considered this an
important reason for the absence of adrenal tumors in intact mice (3).
We therefore assumed that adrenal tumorigenesis could also be induced
in TG mice if they are functionally gonadectomized by treatment
with a GnRH antagonist or by cross-breeding them into the genetic
background of the gonadotropin-deficient hypogonadal hpg
mutant mouse (8). However, no adrenal tumors were found in either of
these models despite their dramatically suppressed inhibin secretion
(4). This prompted us to rule out the role of gonadal inhibin as the
suppressor of adrenal tumorigenesis in intact TG mouse. We therefore
hypothesized that it could be related to the elevated gonadotropin
secretion, which is the most obvious difference between the surgical
and functional gonadectomy models. The present findings demonstrate
that the adrenal cortex of the TG mice contains LHR which, when
coexpressed with Tag, triggers tumorigenesis in the presence of high LH
stimulation, as occurs after surgical gonadectomy.
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RESULTS |
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TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
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LH Receptor (LHR) Expression in Adrenal Tumor Cells and Tissue
The first piece of evidence for LHR expression in the adrenal
tumors is provided by Northern hybridization. Clear LHR message with
similar proportions of the different splice variants was detected in
the adrenal tumors and C1 cells, which was very similar to that of
the mouse testis, used as positive control (Fig. 1
). No specific hybridization was
observed in the non-TG control adrenals. Even a sensitive RT-PCR method
was unable to demonstrate LHR mRNA in adrenal glands of intact and
gonadectomized wild-type mice, of both sexes, when studied at the age
of 19 days, 2 months, and 5 months (result not shown). RT-PCR of intact
TG mice detected, in agreement with the receptor- binding measurements
(see below), LHR mRNA in adrenal glands at the age of 6 months, but not
in younger animals (results not shown).
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1 cells (8,000 receptors per cell).
However, it is lower than that measured in the BLT-1 murine Leydig
tumor cells (47,000 receptors per cell) used as positive control. The
equilibrium dissociation constant (Kd) of hCG binding to
the adrenal cell receptors was similar to that detected in the Leydig
tumor cells (6.8 pmol/liter vs. 22 pmol/liter) (Fig. 2).
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). It was clearly detectable in the
adrenal tumors of the gonadectomized TG mice, but also, albeit at lower
levels, in the adrenal glands of the gonad-intact TG mice. The IT6-F
line showed higher binding than the IT6-M TG line, but no sex
differences were observed between the LHR levels. Low but significant
hCG binding was also observed in the non-TG hpg mice, but
not in any of the non-TG mice (Fig. 3). In both TG lines, the adrenal
LHR persisted after the GnRH-antagonist treatment, albeit at somewhat
lower levels (result not shown).
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1 cells when examined by RT-PCR (result not shown).
hCG-Stimulated cAMP and Steroid Production of the C1 Adrenal
Tumor Cells
cAMP production of the C1 adrenal tumor cells was stimulated in
dose-dependent fashion by hCG, the highest increase occurring between
doses 1–10 µg/liter. The maximum stimulation was about 15-fold over
the nonstimulated controls (Fig. 4). This
finding provides clear evidence that the LHR in the adrenal tumor cells
are functional. The steroidogenesis of the cells was monitored by
production of progesterone, which, rather than corticosterone, was
previously found to be the main steroid produced by the C1 cells
(3). The basal level of progesterone production was high, and a
dose-dependent moderate increase, up to 40% (P <
0.01), was observed in response to hCG (Fig. 4). As expected, the
ED50 of the progesterone response was about 10-fold lower
than that of cAMP (1 vs. 8 µg/liter).
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1
Adrenal Tumor Cells1 cells was significantly stimulated
by treatment with intermediate doses of hCG, as monitored by
[3H]thymidine incorporation (Fig. 5). Likewise, treatment with progesterone
caused a dose-dependent significant increase in
[3H]-thymidine incorporation of the same cells (up to
80%, Fig. 5). The minimum effective dose of progesterone was 30
nmol/liter. Testosterone had a stimulating effect on C1 cell
proliferation, up to 2-fold from control, and the lowest effective dose
tested was 10 nmol/liter (Fig. 5). A stimulating effect was also found
with estradiol treatment, and maximum stimulation was found at a dose
of 2 nmol/liter (Fig. 5).
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). Both types of cells were organized in
columnar arrays. The Tag immunoreactivity was clearly localized in the
nuclei, whereas that of the LHR was strongest in the periphery of the
cells. Although the majority of the two immunoreativities was localized
in different cells, the possibility of some of the immunopositive cells
expressing both antigens could not be excluded in the serial sections
analyzed. In fact, this is evident since the same adrenocortical tumor
cell line (C1), derived from one of these tumors, was positive both
for Tag, as shown before (3), and for the LHR, as show in this
study. The tumor growth originated from the juxtamedullary part of
the adrenal cortex (3), which indicates the X-zone as the origin of the
malignant growth.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
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p/Tag mice develop adrenal tumors only if they are
neonatally gonadectomized (3, 4). The gonadal tumors produced high
levels of inhibin, which also suppressed proliferation of the C1
cells, derived from one of the adrenal tumors (3). We therefore
hypothesized, based on the tumor suppressor function of inhibin (5),
that the elimination of this peptide by gonadectomy triggers the
adrenal tumorigenesis. To obtain direct proof for this, we performed
functional gonadectomy of the TG mice by treating them with a GnRH
antagonist or by cross-breeding them into the hypogonadotropic
hpg genetic background (4). No gonadal tumors were formed in
these mice, demonstrating the gonadotropin dependence of these
malignancies. Neither were adrenal tumors found despite the suppressed
inhibin levels, which demonstrated that gonadectomy, rather than
eliminating a gonadal tumor suppressor, brought about a factor
stimulating adrenal tumorigenesis. Since the high gonadotropin levels
after removal of gonads are the most obvious difference between the two
experimental models, this hormonal change was considered somehow
responsible for the appearance of the adrenal tumors.
Quite surprisingly, we found a high level of LHR gene expression in the
tumorous adrenal glands. A low level of LHR was also present in the
adrenal glands of the intact TG mice, but never in those of the
wild-type mice. Although there is circumstantial evidence for LH
responsiveness of the mouse adrenal gland (see below), our finding is
to our knowledge the first piece of direct evidence for this. That the
expression was so high after gonadectomy is surprising, since high LH
levels usually down-regulate the cognate receptor expression (9). This
suggests that the regulation of the adrenal tumor LHR gene may differ
from that in gonads. LH has been shown to stimulate inhibin
expression (10, 11), which explains why the high postgonadectomy LH
levels apparently increased the Tag transgene expression, thereby
triggering the adrenal tumorigenesis. The absence of FSH receptor
expression in the adrenal tumors rules out a role of FSH in the
tumorigenesis, although the concentration of this hormone is also
dramatically increased after gonadectomy.
The present findings shed some more light on the existing indirect data on LH responsiveness of the immature mouse adrenal gland. The mouse adrenal cortex consists of three structurally and functionally distinct layers, i.e. zona glomerulosa, fasciculata, and, unlike other mammalian species, the X-zone (12). The existing findings on function of the X-zone are rather confusing. Although never directly demonstrated, several pieces of data suggest that the X-zone may be responsive to LH. It normally disappears during postnatal development, at puberty in males and after the first pregnancy in females, but it survives after neonatal gonadectomy (12, 13, 14). It also disappears after hypophysectomy but can be preserved by LH treatment (13). A theory has been postulated that LH maintains the X-zone whereas testicular androgens, as well as androgens of unknown origin during pregnancy, cause its involution (12). Absence of this effect may explain why we found a low level of LHR in the adult hpg mouse adrenal glands. The role of LH in the ontogeny of the mouse adrenal cortex clearly needs to be revisited.
With regard to the LH responsiveness of the human adrenal cortex, the findings are also scanty and controversial (15, 16). Very recently, Pabon et al. (17) demonstrated LHR mRNA and immunoreactivity in the human adrenal cortex, but the physiological significance of this finding remains open in the absence of functional data. In contrast, several reports exist on LH responsiveness of human adrenocortical tumors (see, e.g. Refs. 18–20). The relevance of these findings with the present TG model is unclear, since human adrenal tumors with LH responsiveness have been speculated to originate from metaplasia of ovarian theca cells or embryologically competent mesenchymal cell to the adrenal gland (21, 22). In contrast, the presence of LHR in the TG mouse adrenals seems to be strictly related to the Tag expression, occurring only in intact and gonadectomized TG mice at the age of about 6 months.
The adrenal LHR and Tag expression of the gonadectomized TG mice did not follow the anatomical zonation before apparent tumor formation. Both immunoreactivities appeared in cord-like radial structures spanning the adrenal cortex. Interestingly, they appeared to be localized mainly in different cells at this stage. The adrenal tumors always originate from the juxtamedullary X-zone (3), and since they express both LHR and Tag in large amounts, both of them are apparently needed for tumorigenesis. The ligand-stimulated LHR functions as a tumor promoter in this case.
The induction mechanism of LHR expression in gonadal steroidogenic cells is still unknown. It is curious that similar transcription factors, e.g. SF-1, WT-1, and DAX-1, participate in induction of the embryonic differentiation of gonadal and adrenal somatic cells (23, 24, 25), but finally different tropic hormones regulate the two cell types in later life, i.e. ACTH and angiotensin II in the adrenal gland, and gonadotropins in gonads. What brings about this difference in cells that were originally under very similar induction mechanisms, remains unknown. The difference may, in fact, be quantitative rather than strictly qualitative, since low-level LHR expression in the adrenal gland, in particular the mouse adrenal X-zone, may be a normal phenomenon (17). The current TG model will be a good tool for further exploration of this matter.
As expected on the basis of the in vivo findings, hCG
increased the thymidine incorporation of the C1 cell line. Since
progesterone, testosterone, and estradiol also displayed similar
effects on the tumor cells, the LH-stimulated steroidogenesis may be
the crucial growth signal. Of these steroids, progesterone and
estradiol were found to be actively produced by the adrenal tumors (3).
A role for LH in adrenal tumorigenesis is also possible in normal mice,
since certain mouse strains appear to develop adrenal tumors after
gonadectomy (26). Since gonadal tumors also appear in TG mice
overexpressing LH (27), this hormone seems to have tumor promoter
activity if a first hit (in the present model Tag) has sensitized a
cell lineage to malignant growth. Hence, the present TG mice provide a
good model for genesis of hormone-dependent cancer. Upon expression of
a potent oncogen (Tag), a tropic hormone functions as a tumor promoter
triggering the malignant growth.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
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p/Tag as described
previously (1, 2). Males and females of lines IT6-M and IT6-F were
used. Genotypic hpg mice (8) were purchased from the Jackson
Laboratory (Bar Harbor, ME) and bred in our own vivarium. Genotyping of
the mice was carried out from tail DNA by PCR (1, 8, 28). The mice were
specific pathogen-free and housed four to six per cage in controlled
conditions of light (12 h light, 12 h darkness) and temperature
(21 ± 1 C). They were fed with commercial mouse chow SDS RM-3
(Special Diet Service; E, soy-free; Whitham, Essex, UK) and tap water
ad libitum. All the procedures using mice were approved by
the University of Turku Ethical Committee on Use and Care of
Animals.
Gonadectomy
TG mice (12 females, 11 males) of the IT6-M line and non-TG mice (9
females, 9 males) were castrated at the age of 4 weeks. The
heterozygous TG animals were derived from matings of TG males of the
IT6-M line (1, 2, 3) with DBA/2J or C57Bl/6 females. Avertin anesthesia
(29) during surgical procedures and postoperative analgesia
(buprenorphine, 3 mg/mouse, ip) were used. The mice were weighed every
other week and inspected daily for potential signs of tumorigenesis.
The mice were killed at 6–8 months of age (i.e. 5–7 months
after gonadectomy).
GnRH Antagonist Treatment
Six males and seven females of the IT6-M TG mouse line and five males
and six females of the IT6-F TG mouse line (all TG heterozygous,
derived as above) were injected subcutaneously every 84 h with the
GnRH antagonist Cetrorelix acetate (SB-75; Asta Medica AG, Frankfurt am
Main, Germany) in 5% mannitol. The dosage of SB-75 was 10 mg/kg body
weight per injection. The control group receiving 5% mannitol
injections consisted of age-matched TG mice (8 males and 12 females of
both lines) and SB-75-treated non-TG mice (1 female, 2 males). The
treatment was started at the age of 3 months and lasted for 12 wk, and
the mice were killed 3 days after the last injection.
hpg Experiment
At the first mating, TG males of both IT6 lines were cross-bred with
females heterozygous (HT) for the hpg mutation (HT females)
(4). TG males heterozygous for hpg (Tag/HT males), derived
from the first mating, were further cross-bred with HT females to
create the hypogonadal transgenic (Tag/hpg) mice used in
this study (6 males, 4 females). Tag/HT mice (24 of each sex) served as
controls. The mice were killed at the age of 6 months. The findings on
gonadal tumorigenesis of the GnRH antagonist-treated and hpg
mice have been reported previously (4).
At the end of the treatment/follow-up periods, the mice were anesthetized with Avertin (29) and laparotomy was performed. The adrenal glands were collected, weighed, and snap-frozen in liquid nitrogen or fixed in Bouin’s solution for histological analysis.
Cell Line Stimulations
C1 cells, derived previously from one of the TG adrenal
tumors (3), were used. One day before stimulation, the C1 cells were
plated on 24-well plates (Greiner, Labortechnik, Frickenhausen,
Germany) at a density of 105 cells per well in 0.5 ml of
the culture medium, i.e. DMEM/F12 (1:1, with 0.365 g/liter
L-glutamine; Life Technologies, GIBCO BRL, Glasgow,
Scotland), 10% heat-inactivated FCS (Bioclear, Berks, UK), 4.5 g/liter
glucose, 20 mmol/liter HEPES, 0.1 g/liter gentamicin (Biological
Industries, Bet-HaEmek, Israel), and 1.25 mg/liter fungizone (GIBCO),
and incubated for 24 h. Each experiment was performed with
quadruplicate samples and repeated three to five times. The cells were
washed with 1 x PBS (PBS, pH 7.4) and incubated for 24 h in
1 ml of DMEM/F12 + 0.1% BSA (Sigma Chemical Co., St.Louis, MO) and 0.2
mmol/liter of 3-isobutyl-1-isometylxanthine (Aldrich-Chemie, Steinheim,
Germany) in the presence and absence of different concentrations of hCG
(NIH CR-121, 11500 IU/mg, NIH, Bethesda, MD), progesterone,
testosterone, or estradiol (all from Sigma). After incubation for
1 h, aliquots of the media were collected for measurement of cAMP
by RIA (30, 31). After incubation for 8 h, samples of the media
were collected for progesterone RIA (32), and
[3H]thymidine (3 µCi; Amersham, Amersham Intl. plc.,
Buckinghamshire, UK) was added to the cell cultures before measurement
of DNA synthesis (see below), and the incubation was continued until
24 h.
Measurement of DNA Synthesis
A method described previously (33) was used with some
modifications. The cells were fixed by incubation for 10 min in 0.5 ml
of ice-cold 100% MeOH. The fixed cells were washed once with 1x HBSS
(GIBCO) and once with 1 ml of ice-cold 10% trichloroacetic acid,
incubated for 10 min, and washed again twice with 10% trichloroacetic
acid for 5 min. After addition of 0.5 ml of 0.3 N NaOH/1%
sodium dodecyl sulfonate, the cell were incubated for 30 min at room
temperature. The tritium content in the cell lysates was determined by
liquid scintillation spectrometry.
LH Receptor-Binding Assay
Highly purified hCG (CR-121) was iodinated with
[125I]NaI (IMS 300, Amersham) using a solid-phase
lactoperoxidase method described previously (34, 35). The specific
activity of the preparation used was 50 Ci/g, with maximum binding of
25% to an excess of mouse testicular membranes. For Scatchard
analysis, the C1 adrenal tumor cells (40,000 cells per tube) were
incubated in a reaction volume of 250 µl with different dilutions of
the tracer (15,000–500,000 cpm/tube) and in the presence and absence
of 50 IU of unlabeled hCG (Pregnyl; 3,000 IU/mg, Organon, Oss, The
Netherlands). As a positive control, the LHR were determined as above
in a mouse Leydig tumor cell line, BLT-1 (2).
For LHR assay of normal and tumorous adrenal tissues, pairs of the glands were homogenized in 2 ml of Dulbecco’s PBS + 0.1% BSA, and 100-µl aliquots of the crude homogenates were incubated with 100,000 cpm/tube of the [125I]iodo-hCG tracer, in the presence and absence of 50 IU of nonradioactive hCG (Pregnyl). The LH binding was corrected according to the protein content of the adrenal gland homogenates (36). hCG binding of the mouse testis homogenate, measured in the same way, was used as positive control.
Northern Hybridization
Total RNA from mouse testis, normal and tumorous adrenal tissue,
and C1 cells was isolated by the guanidinium
isothiocyanate/CsCl2 method (37). Twenty micrograms of
total RNA were resolved on 1.2% formaldehyde denaturing agarose gel
and transferred onto nylon membrane (Hybond-N, Amersham). For
hybridization, a complementary RNA probe for the rat LHR was generated
from a fragment of the LHR cDNA, spanning nucleotides 441–849 of its
extracellular domain, subcloned into pGEM-4Z plasmid (38). The
32P-labeled probe was generated using a Riboprobe system II
kit (Promega, Madison, WI) and the cDNA as template. Prehybridization,
hybridization, and subsequent membrane washings were performed as
described previously (39). The filters were exposed to x-ray film
(Kodak XAR-5, Eastman Kodak, Rochester, NY) at -70 C for up to 7
days.
Detection of LHR and FSH Receptor mRNA by RT-PCR
Total RNA from tissues and cell were extracted as described
above (37). Two micrograms of total RNA were reverse-transcribed using
the avian myeloma virus RT (Promega, Madison, WI), and the primer pairs
used were specific for the rat FSH and LH receptor sequences. For the
FSH receptor, the sense primer, 5'-ATGGCTGAGTAAGAATGGGA-3',
corresponded to nucleotides 560–579, and the antisense primer,
5'-CTTGCCTTAAAATAGACTTGTTGC-3', corresponded to nucleotides 933–908 of
the cDNA (40, 41). For the LH receptor, the sense primer,
5'-CTCTCACCTATCTCCCTGTC-3', corresponded to nucleotides 179–195, and
the antisense primer, 5'-TCTTTCTTCGGCAAATTCCTG-3', corresponded to
nucleotides 878–858 of the respective cDNA (39, 42). For
amplification, the Dynazyme thermostable recombinant DNA polymerase
(Promega, Madison, WI) was used in a thermal cycler. In the first step,
reaction was started at 50 C for 10 min (RT), followed by a period of 3
min at 97 C and then run for 40 PCR cycles (96 C for 1.30 min; 53 C for
1.30 min; 72 C for 2 min) and the final extension for 10 min at 72 C,
as described by us previously for LH receptor and FSH receptor cDNA
amplification (39, 42).
Immunocytochemistry
Paraformaldehyde-fixed paraffin sections (5 µm thick) of
adrenal glands were dewaxed, incubated in 0.3%
H2O2 in ethanol to block endogenous
peroxidases, rehydrated, and incubated further with 3% normal goat
serum in Tris-buffered saline (pH 7.6). Serial sections of the adrenal
glands were reacted either with a polyclonal rabbit antiserum directed
against the N-terminal sequence (amino acids 15–38) of the rat LHR
(1:250–1:1000 dilution of the lyophilysate in H2O) (kindly
donated by Dr. P. C. Roche, Rochester, MN) or a rabbit polyclonal
anti-Tag antibody (1:500–1:5000 dilution in PBS) (kindly donated by
Dr. D. Hanahan, University of California, San Francisco, CA) (43). The
slides were incubated at 4 C overnight. The bound antibodies were
visualized with the immunoperoxidase technique (Vectastain Elite ABC
kit, Vector, Burlingame, CA).
Statistical Analysis
A MacIntosh version of the SuperANOVA program (Abacus Concepts,
Inc., Berkeley, CA) was used for one-factor ANOVA, followed by
factorial tests, Duncan’s new multiple range test, and Fisher’s
protected least significant difference post hoc tests.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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This work was supported by grants from The Sigrid Jusélius Foundation, The Finnish Cancer Societies, and The Academy of Finland.
Received for publication November 3, 1997. Revision received January 23, 1998. Accepted for publication February 13, 1998.
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REFERENCES |
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TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIALS AND METHODSREFERENCES |
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M. Ascoli Learning New Tricks from an Old Dog: The Processing of the Intracellular Precursor of the Luteinizing Hormone Receptor (LHR) into the Mature Cell-Surface LHR Is a Regulated Process Endocrinology, August 1, 2005; 146(8): 3221 - 3223. [Full Text] [PDF]
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P. M. Apaja, J. T. Aatsinki, H. J. Rajaniemi, and U. E. Petaja-Repo Expression of the Mature Luteinizing Hormone Receptor in Rodent Urogenital and Adrenal Tissues Is Developmentally Regulated at a Posttranslational Level Endocrinology, August 1, 2005; 146(8): 3224 - 3232. [Abstract] [Full Text] [PDF]
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 G. Piaditis, A. Angellou, G. Kontogeorgos, N. Mazarakis, T. Kounadi, G. Kaltsas, K. Vamvakidis, R. V. Lloyd, E. Horvath, and K. Kovacs Ectopic Bioactive Luteinizing Hormone Secretion by a Pancreatic Endocrine Tumor, Manifested as Luteinized Granulosa-Thecal Cell Tumor of the Ovaries J. Clin. Endocrinol. Metab., April 1, 2005; 90(4): 2097 - 2103. [Abstract] [Full Text] [PDF]
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N. A. Rahman, S. Kiiveri, A. Rivero-Muller, J. Levallet, S. Vierre, J. Kero, D. B. Wilson, M. Heikinheimo, and I. Huhtaniemi Adrenocortical Tumorigenesis in Transgenic Mice Expressing the Inhibin {alpha}-Subunit Promoter/Simian Virus 40 T-Antigen Transgene: Relationship between Ectopic Expression of Luteinizing Hormone Receptor and Transcription Factor GATA-4 Mol. Endocrinol., October 1, 2004; 18(10): 2553 - 2569. [Abstract] [Full Text] [PDF]
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 Ch.V. Rao, X.L. Zhou, and Z.M. Lei Functional Luteinizing Hormone/Chorionic Gonadotropin Receptors in Human Adrenal Cortical H295R Cells Biol Reprod, August 1, 2004; 71(2): 579 - 587. [Abstract] [Full Text] [PDF]
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M. Bielinska, H. Parviainen, S. B. Porter-Tinge, S. Kiiveri, E. Genova, N. Rahman, I. T. Huhtaniemi, L. J. Muglia, M. Heikinheimo, and D. B. Wilson Mouse Strain Susceptibility to Gonadectomy-Induced Adrenocortical Tumor Formation Correlates with the Expression of GATA-4 and Luteinizing Hormone Receptor Endocrinology, September 1, 2003; 144(9): 4123 - 4133. [Abstract] [Full Text] [PDF]
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 A. Turturro, P. Duffy, B. Hass, R. Kodell, and R. Hart Survival Characteristics and Age-Adjusted Disease Incidences in C57BL/6 Mice Fed a Commonly Used Cereal-Based Diet Modulated by Dietary Restriction J. Gerontol. A Biol. Sci. Med. Sci., November 1, 2002; 57(11): B379 - 389. [Abstract] [Full Text] [PDF]
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S. B. Rulli, A. Kuorelahti, O. Karaer, L. J. Pelliniemi, M. Poutanen, and I. Huhtaniemi Reproductive Disturbances, Pituitary Lactotrope Adenomas, and Mammary Gland Tumors in Transgenic Female Mice Producing High Levels of Human Chorionic Gonadotropin Endocrinology, October 1, 2002; 143(10): 4084 - 4095. [Abstract] [Full Text] [PDF]
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T. Hamalainen, J. Kero, M. Poutanen, and I. Huhtaniemi Transgenic Mice Harboring Murine Luteinizing Hormone Receptor Promoter/{beta}-Galactosidase Fusion Genes: Different Structural and Hormonal Requirements of Expression in the Testis, Ovary, and Adrenal Gland Endocrinology, October 1, 2002; 143(10): 4096 - 4103. [Abstract] [Full Text] |
