Local aromatase excess with recruitment of unusual promoters of CYP19A1 gene in prepubertal patients with gynecomastia

OBJECTIVES

Gynecomastia may be due to aromatase excess in several diseases such as obesity and cancer. Aromatase excess syndrome (AEXS) is an autosomal dominant disorder caused by overexpression of CYP19A1. Germinal mutations occurring in AEXS include various genomic rearrangements including duplication, deletion, and inversion identified in the upstream region of CYP19A1. Aromatase overexpression caused by a CYP19A1 somatic mutation has been rarely described.

METHODS

Breast adipose tissue biopsies or surgical specimens were obtained from 19 subjects with gynecomastia. Aromatase quantification was performed by digital PCR and CYP19A1 sequencing by RACE PCR products.

RESULTS

We observed localized aromatase overexpression (>10 fold greater than normal) in breast adipose tissue from three prepubertal males with gynecomastia out of the 19 cases. One carried a chromosomal rearrangement between CYP19A1 and DMXL2, consistent with AEXS. In the 2 others, the first exon of CYP19A1 contained 11 different tissue-specific promoter subtypes, specifically I.4 or I.3 normally expressed by adipose tissue, but also the placental I.2 promoter and the more ubiquitous I.7 which is usually expressed in breast cancer, uterine, and endothelial tissues. No differences in clinical or biochemical characteristics were observed between these 3 subjects and 16 others without aromatase overexpression.

CONCLUSIONS

We describe two cases of aromatase overexpression in breast adipose tissue associated with nonspecific promoter recruitment. Further investigations are necessary to understand the mechanisms involved in aberrant promoter selection.

Overlapping Phenotypes Associated With CYP24A1, SLC34A1, and SLC34A3 Mutations: A Cohort Study of Patients With Hypersensitivity to Vitamin D

Mutations in CYP24A1 (vitamin D 24-hydroxylase) and SLC34A1 (renal phosphate transporter NPT2a) cause autosomal recessive Infantile Hypercalcemia type 1 and 2, illustrating links between vitamin D and phosphate metabolism. Patients may present with hypercalciuria and alternate between chronic phases with normal serum calcium but inappropriately high 1,25-(OH)₂D and appropriately low PTH, and acute phases with hypercalcemia with suppressed PTH. Mutations in SLC34A3 and SLC9A3R1 have been associated with phosphate wasting without hypercalcemia. The aims of this study were to evaluate the frequency of mutations in these genes in patients with a medical history suggestive of CYP24A1 mutation to search for a specific pattern. Using next generation sequencing, we screened for mutations in 185 patients with PTH levels < 20 pg/mL, hypercalcemia and/or hypercalciuria, and relatives. Twenty-eight (15%) patients harbored biallelic mutations in CYP24A1 (25) and SLC34A3 (3), mostly associated with renal disease (lithiasis, nephrocalcinosis) (86%). Hypophosphatemia was found in 7 patients with biallelic mutations in CYP24A1 and a normal phosphatemia was reported in 2 patients with biallelic mutations in SLC34A3. Rare variations in SLC34A1 and SLC34A3 were mostly of uncertain significance. Fifteen patients (8%) carried only one heterozygous mutation. Heterozygous relatives carrying SLC34A1 or SLC34A3 variation may present with biochemical changes in mineral metabolism. Two patients' genotype may suggest digenism (heterozygous variations in different genes). No variation was found in SLC9A3R1. As no specific pattern can be found, patients with medical history suggestive of CYP24A1 mutation should benefit from SLC34A1 and SLC34A3 analysis.

Genetic counseling for cystic fibrosis: A basic model with new challenges

While the goals of genetic counseling for cystic fibrosis - delivering relevant information on the risk of recurrence and nondirectional support of couples at risk in their reproductive choices - have not changed fundamentally, the practice has evolved considerably in the last decade, growing more complex to face new challenges but also proving more effective. Many factors have contributed to this evolution: technical progress in the exploration of the genome (new generation sequencing) and in reproductive medicine, but also societal developments promoting access to genetic information and the professionalization of genetic counselors in France. The prospect of expanded pre-conception screening of at-risk couples makes genetic counselors major actors not only in medical care centers, but also in modern society by contributing to genetic education among citizens. © 2020 French Society of Pediatrics. Published by Elsevier Masson SAS. All rights reserved.

Maternal Transmission Ratio Distortion of GNAS Loss-of-Function Mutations

Pseudohypoparathyroidism type 1A (PHP1A) and pseudopseudohypoparathyroidism (PPHP) are two rare autosomal dominant disorders caused by loss-of-function mutations in the imprinted Guanine Nucleotide Binding Protein, Alpha Stimulating Activity (GNAS) gene, coding G_s α. PHP1A is caused by mutations in the maternal allele and results in Albright's hereditary osteodystrophy (AHO) and hormonal resistance, mainly to the parathormone (PTH), whereas PPHP, with AHO features and no hormonal resistance, is linked to mutations in the paternal allele. This study sought to investigate parental transmission of GNAS mutations. We conducted a retrospective study in a population of 204 families with 361 patients harboring GNAS mutations. To prevent ascertainment bias toward a higher proportion of affected children due to the way in which data were collected, we excluded from transmission analysis all probands in the ascertained sibships. After bias correction, the distribution ratio of the mutated alleles was calculated from the observed genotypes of the offspring of nuclear families and was compared to the expected ratio of 50% according to Mendelian inheritance (one-sample Z-test). Sex ratio, phenotype of the transmitting parent, and transmission depending on the severity of the mutation were also analyzed. Transmission analysis was performed in 114 nuclear families and included 250 descendants. The fertility rates were similar between male and female patients. We showed an excess of transmission from mother to offspring of mutated alleles (59%, p = .022), which was greater when the mutations were severe (61.7%, p = .023). Similarly, an excess of transmission was found when the mother had a PHP1A phenotype (64.7%, p = .036). By contrast, a Mendelian distribution was observed when the mutations were paternally inherited. Higher numbers of females within the carriers, but not in noncarriers, were also observed. The mother-specific transmission ratio distortion (TRD) and the sex-ratio imbalance associated to PHP1A point to a role of G_s α in oocyte biology or embryogenesis, with implications for genetic counseling. © 2019 American Society for Bone and Mineral Research.

High frequency of paternal iso or heterodisomy at chromosome 20 associated with sporadic pseudohypoparathyroidism 1B

Pseudohypoparathyroidism 1B (PHP1B) is caused by maternal epigenetic defects in the imprinted GNAS cluster. PHP1B can follow an autosomal dominant mode of inheritance or occur sporadically (spor-PHP1B). These latter patients present broad methylation changes of two or more differentially methylated regions (DMR) that, when mimicking the paternal allele, raises the suspicious of the occurrence of paternal uniparental disomy of chromosome 20 (upd(20)pat). A cohort of 33 spor-PHP1B patients was screened for upd(20)pat using comparative genomic hybridization with SNP-chip. Methylation analyses were assessed by methylation specific-multiplex ligation-dependent probe amplification. Upd(20)pat was identified in 6 patients, all exhibiting typical paternal methylation pattern compared to normal controls, namely a complete loss of methylation of GNAS A/B:TSS-DMR, negligible methylation at GNAS-AS1:TSS-DMR and GNAS-XL:Ex1-DMR and complete gain of methylation at GNAS-NESP:TSS-DMR. The overall frequency of upd(20) is 18% in our cohort when searched considering both severe and partial loss of imprinting. However, twenty five patients displayed severe methylation pattern and the upd(20)pat frequency reaches 24% when searching in this group. Consequently, up to day, upd(20)pat is the most common anomaly than other genetic alterations in spor-PHP1B patients. Upd(20)pat occurrence is not linked to the parental age in contrast to upd(20)mat, strongly associated with an advanced maternal childbearing age. This study provides criteria to guide further investigations for upd(20)pat needed for an adequate genetic counseling.

Unusual clinical description of adult with Timothy syndrome, carrier of a new heterozygote mutation of CACNA1C

CANAC1C encodes for the main cardiac L-type calcium channel and mutations on it lead to a prolonged QT interval in Timothy Syndrome (TS). We provide a new de novo constitutional heterozygote missense variation in CACNA1C in a living adult woman, also carrier of the known c.2146-1G>C heterozygous variation of PKP2 inherited from her father. To our knowledge, this patient is the first to have the two variations in these genes. Theses clinical and molecular findings expand the clinical and molecular spectrum of TS and show the interest of next generation sequencing or whole exome sequencing in rare disorders, atypical or novel phenotype.

Vitamin D-Dependent Rickets Type 1B (25-Hydroxylase Deficiency): A Rare Condition or a Misdiagnosed Condition?

Vitamin D requires a two-step activation by hydroxylation: The first step is catalyzed by hepatic 25-hydroxylase (CYP2R1, 11p15.2) and the second one is catalyzed by renal 1α-hydroxylase (CYP27B1, 12q13.1), which produces the active hormonal form of 1,25-(OH)₂ D. Mutations of CYP2R1 have been associated with vitamin D-dependent rickets type 1B (VDDR1B), a very rare condition that has only been reported to affect 4 families to date. We describe 7 patients from 2 unrelated families who presented with homozygous loss-of-function mutations of CYP2R1. Heterozygous mutations were present in their normal parents. We identified a new c.124_138delinsCGG (p.Gly42_Leu46delinsArg) variation and the previously published c.296T>C (p.Leu99Pro) mutation. Functional in vitro studies confirmed loss-of-function enzymatic activity in both cases. We discuss the difficulties in establishing the correct diagnosis and the specific biochemical pattern, namely, very low 25-OH-D suggestive of classical vitamin D deficiency, in the face of normal/high concentrations of 1,25-(OH)₂ D. Siblings exhibited the three stages of rickets based on biochemical and radiographic findings. Interestingly, adult patients were able to maintain normal mineral metabolism without vitamin D supplementation. One index case presented with a partial improvement with 1alfa-hydroxyvitamin D₃ or alfacalcidol (1α-OH-D₃ ) treatment, and we observed a dramatic increase in the 1,25-(OH)₂ D serum concentration, which indicated the role of accessory 25-hydroxylase enzymes. Lastly, in patients who received calcifediol (25-OH-D₃ ), we documented normal 24-hydroxylase activity (CYP24A1). For the first time, and according to the concept of personalized medicine, we demonstrate dramatic improvements in patients who were given 25-OH-D therapy (clinical symptoms, biochemical data, and bone densitometry). In conclusion, the current study further expands the CYP2R1 mutation spectrum. We note that VDDR1B could be easily mistaken for classical vitamin D deficiency. © 2017 American Society for Bone and Mineral Research.

De novo 15q13.3 microdeletion with cryptogenic West syndrome

West syndrome is a well-recognized form of epilepsy, defined by a triad of infantile spasms, hypsarrhythmia and developmental arrest. West syndrome is heterogenous, caused by mutations of genes ARX, STXBP1, KCNT1 among others; 16p13.11 and 17q21.31 microdeletions are less frequent, usually associated with intellectual disability and facial dysmorphism. So-called "idiopathic" West syndrome is of better prognostic, without prior intellectual deficiency and usually responsive to anti-epileptic treatment. We report on a boy falling within the scope of idiopathic West syndrome, with no dysmorphic features and normal development before the beginning of West syndrome, with a good resolution after treatment, bearing a de novo 15q13.3 microdeletion. Six genes are located in the deleted region, including CHRNA7, which encodes a subunit of a nicotinic acetylcholine receptor, and is frequently associated with epilepsy. Exploration of the 15q13.3 region should be proposed in idiopathic West syndrome.

BMP system expression in GCs from polycystic ovary syndrome women and the in vitro effects of BMP4, BMP6, and BMP7 on GC steroidogenesis

BACKGROUND

The bone morphogenetic proteins (BMPs) are growth factors involved in the folliculogenesis. Alteration in their expression may compromise the reproductive process in disease such as the polycystic ovary syndrome (PCOS). This study investigated the expression and role of granulosa cell (GC) BMP from normal cycling and PCOS women.

METHODS AND RESULTS

This prospective study was performed in GCs obtained from 14 patients undergoing IVF: i) six women with normal ovulatory cycles and tubal or male infertility and ii) eight women with PCOS. BMP2, BMP4, BMP5, BMP6, BMP7, and BMP8A and their receptors BMPR1A, BMPR1B, and BMPR2 were identified by RT-PCR in GCs from normally cycling and PCOS women. BMP4, BMP6, and BMP7 expressions were confirmed by immunohistochemistry. Quantitative transcript analysis showed the predominant expression of BMP6. In GCs from PCOS women, an overexpression of BMP6 (P<0.01) and BMPR1A mRNA (P<0.05) was observed. GC culture experiments demonstrated that basal estradiol (E₂) production was threefold higher but FSH-induced E₂ increment was twofold lower in PCOS compared with controls. In PCOS, BMP6 and BMP7 exerted a stimulatory effect on basal E₂ production while BMP4 and BMP6 inhibited FSH-induced E₂ production. FSH receptor and aromatase expression were not different between both groups.

CONCLUSION

The BMP system is expressed in human GCs from normal cycling and PCOS women. The BMP may be involved in reproductive abnormalities found in PCOS.

A new deletion ablating NESP55 causes loss of maternal imprint of A/B GNAS and autosomal dominant pseudohypoparathyroidism type Ib

BACKGROUND

Patients with pseudohypoparathyroidism type Ib (PHP-1b) develop resistance toward PTH, leading to hypocalcemia and hyperphosphatemia. PHP-1b is an imprinted human disorder associated with methylation changes at one or several differentially methylated regions at the GNAS locus. This complex locus gives rise to several different transcripts with different patterns of imprinted expression depending on promoter methylation. They can be either coding [Gαs, XLαs, and neuroendocrine secretory protein-55 (NESP55)] or nontranslated (A/B and AS). The paternal AS transcript lies antisense to nesp55.

OBJECTIVE

Define the genetic defect in a new family with three patients presenting autosomal dominant PHP-1b.

DESIGN

We used methylation analysis, comparative genomic hybridization, and genotyping to characterize the defect. AS expression was studied in two patients and their unaffected mothers.

RESULTS

A novel deletion of 18,988 bp that removes NESP55 and a large part of its counterpart GNAS AS intron 4 was discovered. On maternal transmission, this deletion causes loss of A/B methylation without affecting XL/AS imprint. On paternal transmission, there are no methylation anomalies. The deletion creates a cryptic exon contained within AS intron 4, which is expressed from the mutated allele, be it paternal or maternal.

CONCLUSION

This new deletion suggests that NESP55 is an additional imprinting control region that directs A/B methylation in humans. We bring arguments in support of the theory of reciprocal inhibition between the expression of NESP and AS. However, determining whether loss of methylation at the A/B differentially methylated region is a consequence of the loss of NESP expression or of the expression of AS requires additional investigations.

Array CGH analysis in high-risk pregnancies: comparing DNA from cultured cells and cell-free fetal DNA

OBJECTIVE

To compare results of array comparative genomic hybridization (CGH) on cell-free fetal (cff) DNA from amniotic fluid supernatant and DNA from cultured amniocytes in high-risk pregnancies.

METHOD

We selected 48 cases of high-risk pregnancies (in utero growth retardation [IUGR] and/or at least two fetal malformations [polymalformation]). Bacterial artificial chromosome array CGH (BlueGnome) was performed on 38 fetal samples (frozen cff DNA and DNA from cultured cells) with previously normal karyotypes.

RESULTS

From the 38 specimens, we obtained an adequate amount of sufficient quality DNA with a better quality profile using cff DNA compared to cellular DNA. Aberrations of clinical relevance were detected in three fetuses, and copy number variations considered as benign polymorphism were detected in one case using both sources of DNA. This results in an 8% detection rate of significant abnormalities in high-risk pregnancies with a normal karyotype using array CGH (two cases with IUGR, one with polymalformation).

CONCLUSION

These findings indicate the possibility of using cff DNA from amniotic fluid supernatant for array CGH with excellent results, even in late pregnancy when culture is no longer available. In this small series, pathogenic copy number variations are detected more often in the presence of IUGR than with polymalformation.

Identification by array-Comparative Genomic Hybridization (array-CGH) of a large deletion of luteinizing hormone receptor gene combined with a missense mutation in a patient diagnosed with a 46,XY disorder of sex development and application to prenatal diagnosis

This paper reports the case of an infant presenting with sexual ambiguity at birth. The child presented with labia majora synechia, thready genital tubercle and perineal hypospadias. The karyotype was 46,XY. Low testosterone levels with no response to hCG administration, associated with high LH level for her age, high FSH level, high inhibin B levels and normal AMH indicated a lack of LH receptivity and prompted us to screen the LHCGR gene for mutations. A previously described missense mutation (p.Cys131Arg) was identified at homozygous state in the propositus and at heterozygous state in the mother. This variation, however, was not found in the father. Our attention was drawn by the presence of several single nucleotide polymorphisms (SNPs), identified at homozygous state without any paternal contribution from exon 1 to exon 10 of LHCGR, suggesting a paternal deletion. Array DNA analysis was performed revealing a large deletion extending from 61,493 to 135,344 bp and including the LHCGR gene. Adequate genetic counselling was provided. This paper describes the first application of prenatal diagnosis in LHCGR deficiency for 46,XY disorders of sex development with the subsequent delivery of a normal baby.

Cushing's syndrome associated with a nested stromal epithelial tumor of the liver: hormonal, immunohistochemical, and molecular studies

CONTEXT

Ectopic ACTH syndrome (EAS) is principally associated with aggressive malignant tumors but also with neuroendocrine tumors of good prognosis. Recently, rare nonhepatocytic nested stromal and epithelial tumors (NSET) were characterized by their possible association with Cushing's syndrome of which biochemical and physiopathological features were still incompletely studied.

OBJECTIVE

To describe the clinical and hormonal characteristics of an EAS originating from a liver NSET and further understand the mechanism of cortisol overproduction.

DESIGN AND SETTING

This is a clinical case report from the Endocrinology Department of Caen University Hospital, France.

PATIENT AND INTERVENTION

A 17-year-old female patient was found to have a large liver NSET with mild Cushingoid clinical features and intense biological hypercortisolism but moderate ACTH secretion. Resection of the tumor was curative with a 30-month follow-up.

RESULTS

The epithelial component of the tumor coexpressed ACTH mildly, corticotropin-releasing hormone (CRH) strongly, and 11beta-hydroxysteroid dehydrogenase at a level comparable with normal human hepatocytes.

CONCLUSIONS

Liver NSET is a new cause of EAS, which may evoke hypercortisolism by multiple biochemical pathways.

cAMP-dependent regulation of CYP19 gene in rabbit preovulatory granulosa cells and corpus luteum

Transcription of the CYP19 gene encoding the aromatase P450 enzyme in ovarian cells is under the control of the two gonadotropins, follicle stimulating hormone (FSH) and luteinizing hormone (LH), via modulation of intracellular cyclic 3',5'-adenosine monophosphate (cAMP) levels. Primary cultures of rabbit ovarian cells were used to identify the functional regions of the ovarian promoter (PII) that are responsive to the gonadotropic secondary messenger and to estradiol. Transfection experiments in granulosa and luteal cells with deleted constructs of the PII promoter show that the region between -274 and -193bp is critical for cAMP-dependent transcriptional activity. A comparison of PII activities in granulosa and small luteal cells highlights a 50% decrease consecutive to the LH surge. Sequence analysis of the above mentioned region revealed the presence of a cAMP responsive element like sequence (CLS) and of a nuclear receptor element A (NREA). Binding of CREB to CLS has been shown using granulosa and luteal cells nuclear extracts. In addition, we identified the expression of NR5A1 (Steroidogenic Factor 1) and NR5A2 (Liver Receptor Homologue 1) in granulosa and luteal cells. However, the binding to NREA is observed only with granulosa cells nuclear extracts. Data suggest that the NR5A factors are not the main regulators of CYP19 gene, in contrast with the others genes of streroidogenesis enzymes, and additional sites may play an important role during the post-LH surge down-regulation of CYP19 transcription.

Aromatase expression in the normal human adult adrenal and in adrenocortical tumors: biochemical, immunohistochemical, and molecular studies

OBJECTIVE

The aromatase enzyme catalyzes the final stage of estrogen biosynthesis pathway from androgens. Its expression in the adrenal is poorly studied except for the rare estrogen-producing adrenocortical tumors. In order to further characterize aromatase expression in the adrenal, we evaluated the aromatase enzyme activity, Cyp19a1 gene expression level, and promoter utilization in normal adrenal tissues and in adrenocortical secreting tumors.

DESIGN AND METHODS

Six normal adult adrenals (NA), 2 feminizing adrenal tumors (FT), 10 cortisol-producing adenomas with overt (CS, n=4) or sub-clinical Cushing syndrome (SCS, n=6) and 3 aldosterone-producing adenomas (APA) were studied. Tissue aromatase activity was determined by the tritiated ((3)H)-water method. Total aromatase mRNA were measured by a competitive RT-PCR. Promoter regions PII and PI.4-derived transcripts were also studied in NA, FT, and other steroid-producing tumors by a semi-quantitative comparative RT-PCR. Immunofluorescence analysis was performed in normal human adrenal tissues.

RESULTS

Aromatase activity was detected in NA tissues and in all tumor subtypes, at high levels in both FT. In NA, aromatase immunofluorescence was detected in the cytoplasm of steroidogenic cells, mainly from zona reticularis. Compared with NA, aromatase transcript levels were similar in CS and APA, lower in SCS and similar or higher in FT. Promoter analysis suggested predominant PII utilization in NA, APA, and SCS, but similar PII and PI.4 utilization in CS tumors.

CONCLUSION

Aromatase is expressed at similar levels in normal adrenal and in adrenocortical tumors, but at variably high levels in FT. Different promoter utilization patterns are found among tumor subtypes.

Aberrant adrenal sensitivity to vasopressin in adrenal tumours associated with subclinical or overt autonomous hypercortisolism: is this explained by an overexpression of vasopressin receptors?

OBJECTIVE

Abnormal responsiveness to arginine vasopressin (AVP) was previously observed in cortisol-producing adrenocortical tumours but the mechanism remains unclear. The aim of this study was to characterize the effect of AVP on cortisol secretion from adrenocortical tumours compared to normal human adrenal gland.

DESIGN

A multicentre study based on pharmacological, molecular and immunohistochemical experiments performed in adenomatous and normal adrenal tissues.

PATIENTS

Twenty patients with adrenocortical adenomas and subclinical Cushing's syndrome (SCCS) or Cushing's syndrome (CS) were compared to six control normal subjects.

MEASUREMENTS

In vivo and in vitro cortisol response to vasopressin, vasopressin receptor subtype mRNA measurement by real-time polymerase chain reaction (RT-PCR), immunohistochemical localization of AVP and its V1a receptor in tumour and normal adrenal tissues.

RESULTS

Terlipressin in vivo enhanced cortisol plasma levels in 17/20 SCCS and 3/6 CS but in none of the control subjects. In vitro cortisol response to AVP was observed in nine tumours studied, with enhanced efficacy and/or potency of AVP in three SCCS tumours compared to normal tissues. AVP receptor subtype mRNA levels were similar in SCCS, CS cells and normal adrenal cells. Some SCCS tumour steroidogenic cells showed AVP and V1a receptor immunoreactivity.

CONCLUSIONS

SCCS and CS adrenocortical tumours often exhibit in vivo and in vitro hyper-responsiveness to AVP, which is not related to vasopressin receptor overexpression, but may be explained by more efficient coupling pathways or by the indirect action of AVP through an autocrine/paracrine mechanism.

The absence of a functional nuclear receptor element A (NREA) in the promoter II of the aromatase P450 gene in rabbit granulosa cells

Aromatase protein is synthesized in response to gonadotropins that activate expression of their target genes via the cAMP second messenger system. The -882/+103 bp region of the rabbit ovarian promoter (PII) was ligated to a luciferase vector and transfected into granulosa cells to elucidated the mechanism by which cAMP stimulates transcription. Deletions and mutational experiments indicate that (i) a cAMP-response element-like sequence (CLS) present at -208 to -200 bp is the main element required for the activation of the rabbit PII by cAMP and that (ii) both nuclear receptor element sites; NREA (-133/-126 bp) and NREB (-188/-181 bp) do not participate to the cAMP-dependent activity of the PII. The replacement of the specific rabbit NREA site by the human NREA site increases two-fold the cAMP response and indicates that trans-activating factors are present in rabbit granulosa cells. This study shows for the first time an efficient aromatase transcription occurs in granulosa cells in absence of a consensus NREA site. In addition a comparative study has been performed on the sheep aromatase promoter where sites deviate from rabbit. Mutagenesis experiments suggest that some of them are involved in the cAMP-induced response of the rabbit PII.

Routine detection of EGFR mutations in patients with NSCLC: A comparative study of three alternative methods in 105 patients

7184

Background: The efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) has been reported in lung adenocarcinoma patients with tumoral EGFR mutations. Those mutations were found mainly by direct genomic sequencing on snap-frozen surgical specimens. Conversely, TKIs are used in metastatic patients who do not undergo tumor resection. In these patients, there is a need for routine sensitive molecular procedures, to overcome the small size of non-surgical bronchoscopy paraffin-embedded biopsy samples. Methods: Patients were selected on clinical and pathological characteristics: never (n = 43) or former smokers, patients with non-squamous NSCLC (n = 105) or patients with bronchioloalveolar adenocarcinoma (n = 34). Direct genomic sequencing assay was performed as reported elsewhere. Denaturing, high-performance, liquid chromatography (DHPLC) assay was performed with EGFR-specific primers that amplify exons 18, 19, and 21. A multiplex, allele-specific, oligonucleotide PCR (MASO-PCR) assay was carried out with a set of primers that identify the 14 most frequent molecular events described for the EGFR gene, which covers 90% of EGFR gain-of-function mutations described to date. Results: 123 samples were screened from 105 non-squamous NSCLC patients (female/male ratio = 0.84). Non-surgical biopsy specimens were available in 38 patients. EGFR mutations were detected by at least two of three procedures in 18/105 patients (17%). In paraffin-embedded specimens with low tumor content, EGFR heterozygous mutations were found either by MASO-PCR alone (n = 2, confirmed in the matched surgical sample by another procedure), or both by MASO-PCR and DHPLC (n = 16); they were missed by nucleotidic sequencing in 6 samples. 18 patients received TKI. 6 dramatic responses were achieved in patients with EGFR mutation, while no mutation could be found in non-responsive patients. Overall disease control was obtained in 8/18 patients (44%). Conclusions: MASO-PCR and DHPLC appear more sensitive than direct sequencing in non-surgical paraffin-embedded biopsies, which represent the bulk of samples in lung cancer patients. We propose that the cost-effective MASO-PCR be used for routine screening of EGFR mutations in NSCLC patients.

No significant financial relationships to disclose.

Differential regulation of two 3' end variants of P450 aromatase transcripts and of a new truncated aromatase protein in rabbit preovulatory granulosa cells

In rabbit granulosa cells, two cytochrome P450 aromatase (P450 arom) mRNAs issued from promoter II were described: a full-length and a truncated transcript. Western blot analysis showed two P450 arom proteins with apparent molecular masses of 53 and 46 kDa, which are consistent with the predicted theoretical sizes of proteins encoded by these two transcripts. To examine the involvement of the truncated transcript in the regulation of P450 arom gene expression, the level of each transcript was specifically quantified in cultured granulosa cells by competitive quantitative RT-PCR. FSH induced a dose-dependent increase in both estradiol production and P450 arom mRNAs levels with a much more enhancement in the full-length mRNA. The half-life of the transcripts could not explain this differential regulation. Upon dibutyryl cAMP stimulation, the full-length mRNA was less abundant than the truncated one. In contrast, Western blot analysis revealed a stimulation of the 53-kDa protein content, whereas the 46-kDa protein amount was apparently unaffected. TGF beta in FSH-stimulated conditions decreased both estradiol production and P450 arom transcripts levels. TGF beta did not modify estradiol production and aromatase protein amounts induced by dibutyryl cAMP, whereas the two P450 arom mRNAs levels were increased. In conclusion, we report for the first time that a protein encoded by a truncated P450 arom mRNA could be involved in the regulation of estrogen production. Moreover, we show that the two P450 arom mRNAs are regulated in a differential manner, probably through hormonal control of the alternative splicing.

CFTR genotypes in patients with normal or borderline sweat chloride levels

In recent years, some patients bearing "atypical" forms of cystic fibrosis (CF) with normal sweat chloride concentrations have been described. To identify the spectrum of mutant combinations causing such atypical CF, we collected the results of CFTR (ABCC7) mutation analysis from 15 laboratories. Thirty patients with one or more typical symptoms of the disease associated with normal or borderline sweat chloride levels and bearing two CFTR mutations were selected. Phenotypes and genotypes of these 30 patients are described. A total of 18 different CFTR mutations were observed in the 60 chromosomes analysed. F508del was present in 31.6 % of the mutated chromosomes and 3849+10kbC>T in 13.3 %. R117H, D1152H, L206W, 3272-26A>G, S1235R, G149R, R1070W, S945L, and the poly-T tract variation commonly called IVS8-5T were also observed. The relative frequency of CFTR mutations clearly differed from that observed in typical CF patients or in CBAVD patients with the same ethnic origin. A mild genotype with one or two mild or variable mutations was observed in all the patients. These findings improve our understanding of the distribution of CFTR alleles in CF with normal or borderline sweat chloride concentrations and will facilitate the development of more sensitive CFTR mutation screening.

Involvement of theca cells and steroids in the regulation of granulosa cell apoptosis in rabbit preovulatory follicles

Follicular atresia is characterized by a rapid loss of granulosa cells and, to a lesser extent, theca cells, via apoptosis. The aim of this study was to investigate the possible involvement of theca cell secretions in the regulation of apoptosis of rabbit granulosa cells. The annexin-V binding method based on externalization of phosphatidylserine to the outer layer of plasma membrane during apoptosis was used to detect apoptotic granulosa cells in flow cytometry. Regulation of apoptosis of granulosa cells was studied in three different culture systems: (i) isolated cultured granulosa cells, (ii) granulosa cells obtained from cultured preovulatory follicles and (iii) granulosa cells co-cultured with theca cells. The results of this study indicate that: (i) the rate of apoptosis of granulosa cells was significantly reduced when granulosa cells were co-cultured with theca cells or obtained from cultured preovulatory follicles in comparison with isolated cultured granulosa cells; (ii) FSH exerts its anti-apoptotic effect only on granulosa cells issued from cultured preovulatory follicles; (iii) ovarian steroids do not affect the percentage of isolated apoptotic granulosa cells; and (iv) the occurrence of an apoptotic process in rabbit theca cells could be upregulated in vitro by hCG and an analogue of the gonadotrophin second messenger cAMP. The results of this study indicate that in rabbits (i) steroids were ineffective in vitro in protecting isolated granulosa cells against apoptosis in comparison with observations in vivo in rats, and (ii) the presence of theca cells was efficient to reduce granulosa cell apoptosis but not sufficient to allow the anti-apoptotic effect of gonadotrophins observed in cultured follicles.

Involvement of theca cells and steroids in the regulation of granulosa cell apoptosis in rabbit preovulatory follicles

Follicular atresia is characterized by a rapid loss of granulosa cells and, to a lesser extent, theca cells, via apoptosis. The aim of this study was to investigate the possible involvement of theca cell secretions in the regulation of apoptosis of rabbit granulosa cells. The annexin-V binding method based on externalization of phosphatidylserine to the outer layer of plasma membrane during apoptosis was used to detect apoptotic granulosa cells in flow cytometry. Regulation of apoptosis of granulosa cells was studied in three different culture systems: (i) isolated cultured granulosa cells, (ii) granulosa cells obtained from cultured preovulatory follicles and (iii) granulosa cells co-cultured with theca cells. The results of this study indicate that: (i) the rate of apoptosis of granulosa cells was significantly reduced when granulosa cells were co-cultured with theca cells or obtained from cultured preovulatory follicles in comparison with isolated cultured granulosa cells; (ii) FSH exerts its anti-apoptotic effect only on granulosa cells issued from cultured preovulatory follicles; (iii) ovarian steroids do not affect the percentage of isolated apoptotic granulosa cells; and (iv) the occurrence of an apoptotic process in rabbit theca cells could be upregulated in vitro by hCG and an analogue of the gonadotrophin second messenger cAMP. The results of this study indicate that in rabbits (i) steroids were ineffective in vitro in protecting isolated granulosa cells against apoptosis in comparison with observations in vivo in rats, and (ii) the presence of theca cells was efficient to reduce granulosa cell apoptosis but not sufficient to allow the anti-apoptotic effect of gonadotrophins observed in cultured follicles.

Major hyperestrogenism in a feminizing adrenocortical adenoma despite a moderate overexpression of the aromatase enzyme

A 30-year-old male was referred for the rapid development of gynecomastia, and dramatic hyperestrogenemia was assessed: plasma estrone, estradiol but also cortisol were not suppressed by high-dose dexamethasone, while gonadotropin pulsatility was completely abolished. A 60-mm right adrenal tumor was evidenced on computed tomography-scan, and the patient underwent adrenalectomy. The tumor was found to express a moderate increase in aromatase activity compared with adjacent non-neoplastic adrenal tissue. Quantitative RT-PCR also showed a weak and non-significant increase in total aromatase mRNA in the tumor compared with normal adrenal tissue. Aromatase transcripts were mainly promoter PII-derived, but different patterns of aromatase minor transcripts were found: promoter I.3- and I.6-derived transcripts were identified in the tumor, while only promoter I.4-derived transcripts were found in normal adrenal. This case report demonstrates that a sharp aromatase overexpression is not a prerequisite for clinical and biochemical hyperestrogenism, and further characterizes the aromatase promoter utilization in this feminizing adrenocortical tumor and in the normal adrenal cortex.

Quantification of cytochrome P450 aromatase transcripts before and during luteal phase in rabbit

The aim of the present study was to quantify the promoter II- and I.r-derived transcripts of p450 aromatase gene during follicular stages and during corpus luteum formation in the rabbit. An ovulatory dose of hCG induced, first the disappearance of 90% of aromatase transcripts since 6 h before ovulation, and second a gradual decrease during pseudopregnancy. Individual quantification of both the promoter-derived transcripts showed that promoter II-derived transcript was the main transcript expressed both during follicular phase and pseudopregnancy, but kinetics of disappearance were not similar between both the promoter-derived transcripts. Moreover, hCG up-regulates aromatase expression in vitro in luteal tissue but estradiol, which was without effect on aromatase expression in preovulatory granulosa cells, down-regulates this expression in luteal tissue. In conclusion, the regulation of P450 aromatase in rabbit is mainly under control of promoter II regardless of which cyclic stage is studied. Moreover, we reported an opposite effect of estradiol on aromatase expression in vitro between follicular and luteal cells.

Expression of the rabbit cytochrome P450 aromatase encoding gene uses alternative tissue-specific promoters

The aim of the present study was to analyse the tissue-specific expression of various promoter-derived transcripts from the gene encoding rabbit aromatase cytochrome P450. A new promoter, named I.r, was identified, and promoters II and I.r were sequenced. Promoter I.r-derived transcripts were found in preovulatory granulosa cells, corpus luteum, placenta and adipose tissue. An alternative splice variant of this transcript was found with tissue-specific preference. Tissue-specific expression of promoter-derived variants was studied in the ovary before and after ovulation. While the level of promoter II-derived transcript decreased dramatically after ovulation, that of promoter I.r-derived transcript remained unchanged, indicating that promoter II and promoter I.r were not controlled by a single regulation system. The existence of this dual system of regulation suggests that the rabbit ovary could be a useful model to study the promoter-specific regulation of aromatase.

Spectrum of CFTR mutations in cystic fibrosis and in congenital absence of the vas deferens in France

We have collated the results of cystic fibrosis (CF) mutation analysis conducted in 19 laboratories in France. We have analyzed 7, 420 CF alleles, demonstrating a total of 310 different mutations including 24 not reported previously, accounting for 93.56% of CF genes. The most common were F508del (67.18%; range 61-80), G542X (2.86%; range 1-6.7%), N1303K (2.10%; range 0.75-4.6%), and 1717-1G>A (1.31%; range 0-2.8%). Only 11 mutations had relative frequencies >0. 4%, 140 mutations were found on a small number of CF alleles (from 29 to two), and 154 were unique. These data show a clear geographical and/or ethnic variation in the distribution of the most common CF mutations. This spectrum of CF mutations, the largest ever reported in one country, has generated 481 different genotypes. We also investigated a cohort of 800 French men with congenital bilateral absence of the vas deferens (CBAVD) and identified a total of 137 different CFTR mutations. Screening for the most common CF defects in addition to assessment for IVS8-5T allowed us to detect two mutations in 47.63% and one in 24.63% of CBAVD patients. In a subset of 327 CBAVD men who were more extensively investigated through the scanning of coding/flanking sequences, 516 of 654 (78. 90%) alleles were identified, with 15.90% and 70.95% of patients carrying one or two mutations, respectively, and only 13.15% without any detectable CFTR abnormality. The distribution of genotypes, classified according to the expected effect of their mutations on CFTR protein, clearly differed between both populations. CF patients had two severe mutations (87.77%) or one severe and one mild/variable mutation (11.33%), whereas CBAVD men had either a severe and a mild/variable (87.89%) or two mild/variable (11.57%) mutations.

Presence of exon I.4 mRNA from CYP19 gene in human granulosa cells

Estrogens are synthesized from C19 steroids by a unique form of cytochrome P450 aromatase. Expression of the human CYP19 gene involves tissue specific use of alternative promoters. In the present study, an RT-PCR procedure was used to amplify and quantify various transcripts expressed in human granulosa cells. Cells were aspirated together with follicular fluid from Periovulatory ovarian follicles present in ovaries of 14 patients undergoing a treatment for in vitro fertilization. Sequencing of PCR products demonstrated the presence of exon I.4-specific transcripts in addition to exon P.II, exon I.3 and I.3-truncate transcripts. Quantitative results confirmed that exon P.II specific transcripts were largely predominant compared to other exon-specific transcripts, and that exon I.4-specific transcripts were the least abundant.

Alternative splicing events in the coding region of the cytochrome P450 aromatase gene in male rat germ cells

Expression of cytochrome P450 mRNA in rat germ cells was characterized by reverse transcription PCR with various primers located at the 3'-end of the coding region. At least two unusual isoforms (Ex10-S and INT) of P450 aromatase (P450arom) mRNA were expressed. Analysis of their sequences demonstrated that an alternative splicing event occurred first at the exon-intron boundary of the GT consensus sequence of the last coding exon, and second in the internal 5' donor inside exon 9 used as a minor cryptic splicing site. These isoforms lacked the last coding exon which contained the heme-binding domain; in addition, for the Ex10-S transcript, the catalytic domain was also absent because of a frameshift in the open reading frame. The deduced amino acid sequences led to truncated P450arom polypeptides without the heme-binding domain, which were probably unable to convert androgens into estrogens. Adult rat germ cells are able to express P450arom mRNA, which is then translated into a biologically active enzyme which is involved in estrogen production. Moreover, for the first time, we report the existence of alternative splicing events of P45Oarom mRNA in pachytene spermatocytes and round spermatids, which probably cannot encode functional aromatase molecules.

Expression and immunolocalization of functional cytochrome P450 aromatase in mature rat testicular cells

Aromatase activity has been measured in Leydig cells and Sertoli cells from both immature and mature rats. Cytochrome P450 aromatase (P450arom) has been immunolocalized in germ cells of the rodent, bear, and rooster. Our purpose was to investigate expression of and to immunolocalize P450arom in adult rat testicular cells. After Western blotting with a specific anti-cytochrome P450arom antibody, we demonstrated the presence of a 55-kDa protein in mature rat seminiferous tubules and crude germ cell preparations. Immunoreactive aromatase was detected both in cultured rat Leydig cells and in testis sections (interstitial tissue and elongated spermatids showed positive immunoreactivity for P450arom). We next used reverse transcription-polymerase chain reaction to localize and quantify the P450arom mRNA in the various testicular cells. In rat Leydig cells, the amount of P450arom mRNA was 15 times higher than in Sertoli cells (34.1+/-3.2 to 2.3 +/-0.2 x 10(-3) amol/10(6) cells, respectively). In pachytene spermatocytes, round spermatids, and testicular spermatozoa the P450arom mRNA levels were 38.7+/-8.1, 20.4+/-3.8, and < 1.3 x 10(-3) amol/10(6) cells, respectively. The aromatase activity was 2.5-4 times higher in testicular spermatozoa (8.48+/-1.98 fmol/10(6) cells per hour) than in other germ cells. These results indicate that in mature rats, not only Leydig cells and Sertoli cells but also germ cells have the capacity to express functional P450arom. According to the germ cell maturation state, there was an inverse relationship between P450arom mRNA content and the biological activity of the protein. The expression of the functional P450arom in mature rat germ cells confirms the existence of an additional source of estrogens within the genital tract of the male.

Expression of two aromatase cDNAs in various rabbit tissues

Aromatase is a steroidogenic enzyme complex which catalyses the conversion of androgens to estrogens. In a previous study, we elucidated the structure of a 2.9 kb aromatase cDNA from ovarian rabbit tissue. We report here, the structure of another shorter aromatase cDNA (1.5 kb) from the same tissue. This cDNA is likely to encode for a nonfunctional aromatase which would lack an heme binding domain. We have shown using an RT-PCR technique that rabbit placental tissue, like the ovarian one, expresses both the 2.9 and 1.5 kb cDNA and that the adipose tissue expresses the 2.9 kb cDNA. Using a 5' RACE procedure, we obtained the 5' end of the placental transcripts. Comparison of its sequence with the 5' end of the ovarian one suggests the existence of distinct exon 1 sequences for each one of the two tissues as already described in the human. These results point to the rabbit as a useful laboratory animal for studying regulation of aromatase expression in adipose and placental tissues.

Rapid sequencing of rabbit aromatase cDNA using RACE PCR

The sequencing of aromatase cDNA from rabbit granulosa cells was obtained by RACE PCR. This cDNA is 2.9 kb long. The first 119 nucleotides correspond to the first untranslated exon. Nucleotides 120 to 1,629 correspond to the coding region (1,509 nucleotides) and the rest of the sequence is non coding and contains a polyadenylation signal. Translation of the cDNA sequence indicates that the protein is composed of 503 amino acids, like in human aromatase. Its molecular weight is 57.4 kDa. The alignment between the rabbit aromatase amino acid sequence and other aromatases already described in the human, mouse, rat, cow, pig, chicken, rainbow trout and teleost fish shows that the rabbit protein exhibits the highest homology with the human one (85%).

The possible involvement of LH/hCG induced mitochondrial proteins in the regulation of steroidogenesis in bovine luteal cells

In previous studies we described the synthesis of three mitochondrial proteins (A, B and C) in response to acute in vitro stimulation by lutropin of small bovine luteal cells. Protein A had a molecular weight of 28 kDa and an isoelectric point (pI) of 6.7. Proteins B and C had a molecular mass of 27 kDa and pI of 6.2 and 6.4, respectively. The appearance of these proteins was prevented by 100 microM cycloheximide. In the present study, we have shown that the time course of synthesis of protein A and its hCG dose-response closely parallel the increase in progesterone production. The induction by hCG of protein A was already observed after a 5 min incubation. Pulse chase experiments by addition of excess unlabelled methionine after prelabelling with [35S]methionine indicated that its half-life was approximately 15-20 min. Study of 32P labelled phosphate incorporation into individual proteins and treatment by alkaline phosphatase of [35S]methionine-labelled proteins demonstrated that none of the three proteins A, B or C was a phosphoprotein. Localization of protein A in mitochondria, at the site of the rate limiting step in steroidogenesis, and the high degree of correlation between its 35S labelling and progesterone production argue in favour of its involvement in the acute regulation of steroidogenesis.

Acute stimulation by lutropin of mitochondrial protein synthesis in small luteal cells

A two-dimensional electrophoretic technique was used to study the effect of acute stimulation of bovine luteal cells with lutropin on protein synthesis. Cells were incubated for 30 min with [35S]methionine in the presence of stimulating levels of luteinizing hormone (lutropin), after which the proteins were analyzed by autoradiography. Lutropin or N6,2'-O-dibutyryl-adenosine 3',5'-phosphate (Bt2cAMP) induced the labelling of three proteins, referred to as proteins A, B and C. Protein A, had a molecular mass of 28 kDa and an isoelectric point (pI) of 6.7. Proteins B and C had a molecular mass of 27 kDa and pI of 6.2 and 6.4 respectively. After subcellular fractionation, the three proteins were found to be markedly concentrated in the only fraction enriched in an established mitochondrial marker. Moreover, protein A was one of the major mitochondrial newly synthesized proteins. Its appearance was observed after a 5-min incubation and was prevented by 100 microM cycloheximide. The acute accumulation of proteins A, B and C in mitochondria, the site of the rate-limiting step of steroidogenesis, suggest that they could be involved in the mechanism of stimulation by lutropin of progesterone synthesis.

Involvement of the phospholipase C second messenger system in the regulation of steroidogenesis in small bovine luteal cells

We have previously suggested that the interaction between luteinizing hormone (LH) and its receptor, in addition to stimulating adenylate cyclase, is able to trigger a negative regulatory signal at a step beyond cAMP synthesis (Benhaim et al. (1987) FEBS Lett. 223, 321-326). The present study was conducted to determine whether the phospholipase C system is involved in this phenomenon. Small bovine luteal cells from pregnant cows were incubated with phospholipase C, A23187, an ionophore of calcium and/or phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C (PKC), in the presence or absence of bovine luteinizing hormone or dibutyryl cyclic AMP (dbcAMP). A23187 associated with PMA was able to mimic the stimulatory effect of phospholipase C on basal progesterone production, whereas neither A23187 nor PMA alone had any effect. In the presence of high doses of LH, phospholipase C inhibited progesterone and cAMP production in a dose-dependent manner. A23187 and PMA were able to mimic the inhibition of progesterone synthesis but stimulated LH-induced cAMP accumulation. When cells were stimulated by high doses of dbcAMP, phospholipase C and A23187 but not PMA inhibited progesterone synthesis. These observations suggest that (1) phospholipase C can mimic the post-cAMP negative regulatory signal induced in vitro by high doses of LH, in the presence of an activation of PKC; (2) phospholipase C is also able to mimic in vitro the luteolytic properties of prostaglandin F2 alpha that we previously described (Benhaim et al. (1987) Prostaglandins 33, 227-239); and (3) under basal conditions or in the presence of low doses of LH, the phospholipase C system slightly stimulates steroidogenesis.

Effects of phorbol esters on steroidogenesis in small bovine luteal cells

The possible influence of an activator of protein kinase C, the tumor-promoting phorbol ester, PMA (phorbol-12-myristate-13-acetate), upon small bovine luteal cell steroidogenesis was investigated in vitro, PMA had no significant effect on basal and dibutyryl cyclic AMP (dbcAMP)-stimulated progesterone production but markedly modulated the LH-stimulated progesterone and cAMP productions. PMA potentiated the LH-stimulated cAMP accumulation whatever the dose of LH used. It also potentiated the LH-induced progesterone production in the presence of low doses of LH. Paradoxically, in the presence of maximal or submaximal effective doses of LH, PMA exerted a time- and dose-dependent inhibition of progesterone synthesis. Diacylglycerol was able to mimic the effects of PMA on LH-induced steroidogenesis. These observations suggest that the Ca2+- and phospholipid-dependent protein kinase C can modulate the regulation by LH of small bovine luteal cell steroidogenesis at a step before the synthesis of cAMP. They also suggest that the interaction between LH and its receptor is able to trigger a negative regulatory signal which would be only expressed for high doses of LH and in the presence of an activator of PKC.

In vitro action of PG F2 alpha on progesterone and cAMP synthesis in small bovine luteal cells

The action of prostaglandin F2 alpha (PG F2 alpha) on incubated small bovine luteal cells in the presence or in the absence of bovine luteinizing hormone (LH) or dibutyryl cyclic adenosine monophosphate (db cAMP) was investigated. In the absence of LH and db cAMP, PG F2 alpha stimulated progesterone synthesis at concentrations of 10 ng/ml and 100 ng/ml but had no effects at concentrations below 1 ng/ml. PG F2 alpha partially inhibited the LH or db cAMP stimulated progesterone synthesis. This inhibition was maximal for PG F2 alpha concentrations around 100 pg/ml whereas distinctly higher or lower concentrations were without effect. At the concentration of 100 pg/ml, PG F2 alpha partially inhibited the LH induced cAMP accumulation. These results demonstrate an "in vitro" action of PG F2 alpha on bovine luteal cells. They indicate that the luteolytic action of PG F2 alpha in the bovine species could involve, as already suggested for the rat, both an inhibition of the LH induced synthesis of cAMP and an inhibition of the action of cAMP.

Estradiol membrane binding sites on human breast cancer cell lines. Use of a fluorescent estradiol conjugate to demonstrate plasma membrane binding systems

A fluorescent estradiol macromolecular complex was used to study and to characterize steroid binding to membranes of living target cells. Ligand binding to plasma membranes was quantitated with a sensitivity of 0.1 nM. In this way, we found two types of estradiol-binding sites on hormone sensitive MCF-7 cells. Type A sites (8000-16000 sites per cell) were rapidly saturated at low concentrations of the estradiol-bovine serum albumin-fluorescein isothiocyanate macromolecular complex (E2-BSA-FITC). They had a greater affinity for the complex than did the type B sites for which a phenomenon of cooperative fixation was shown. The complex binding was displaced by estrogenic molecules, but not by non-estrogenic compounds, such as cortisol or progesterone. We also studied complex binding on another breast cancer cell line, MDA-MB-231 (MDA), without intracellular estrogen receptors. These cells showed a specific plasma membrane binding system for estrogen, but lacked the high affinity type A binding site. Then, we report the effects of enzyme treatments (trypsin, phospholipase A2 and neuraminidase) on E2-BSA-FITC binding to MCF-7 cell membranes. The quantity of complex bound to membranes decreased after phospholipase and neuraminidase treatments and increased after trypsin. But, in the three cases, the binding was no longer specific because it could not be displaced by E2-BSA or by estradiol. The enzymatic effects were reversible and specific binding was totally restored within 24 h. However, in the presence of the protein synthesis inhibitor, cycloheximide, no restoration of specific binding occurred on trypsin-treated cells. Estrogen binding to MCF-7 and MDA cell plasma membranes thus possesses the three characteristics of all mediated transport processes across biological membranes: saturability, substrate specificity, and specific inhibition. However, the high affinity type A binding site was found only on the estrogen-sensitive cell line, MCF-7.

Estrogen response of MCF-7 cells grown on diverse substrates and in suspension culture: promotion of morphological heterogeneity, modulation of progestin receptor induction; cell-substrate interactions on collagen gels

In this study we observed the incidence of hormone sensitivity in the response of MCF-7 cells to estrogen stimulation when the cells were cultured in different contact environments (hydrophilic plastic, bovine corneal extracellular matrix, type I collagen and in suspension culture). The major purpose was to describe the influence of cell to cell and cell to substrate contacts on the morphological response to estrogen treatment. However, other parameters including growth and induction of progestin receptor were also explored, keeping in mind that the MCF-7 cell line, although representative of normal mammary epithelium in that it contains a similar hormone receptivity, was selected in vitro from a metastatic population in a pleural effusion. Although substrate conditions did not modify growth enhancement by estrogens, progestin receptor levels were significantly higher in three-dimensional spheroid cultures in which cell to cell contacts were optimal due to elimination of basal contact. A careful morphological survey of large surfaces lead to an objective opinion of the overall effect of the hormone treatment on the non-cloned cell line in which a marked heterogeneity in the response of individual cells was observed. In terms of morphofunctional differentiation, the edification of acini with dense microvillus coating was best in suspension culture. When sections were made perpendicular to the plane of cultures on collagen gel rafts two other phenomena were noted: decrease in intercellular junctions, resulting in reduced cell to cell cohesion, and accumulation biodegradation products in the collagen lattice. This suggested a hormone-mediated interaction between the metastatic cells and the fibrillar substrate, collagen I, one of the major constituents of tissue stroma. This estrogen response might be related to the metastatic phenotype and must be distinct from their hormone sensitivity in terms of growth and differentiation since hormone receptivity is generally considered to be a favorable prognosis for breast cancer.