Shear wave elastography and Afirma™ gene expression classifier in thyroid nodules with indeterminate cytology: a comparison study.

PURPOSE: To compare shear wave elastography (SWE) and Afirma™ gene expression classifier (GEC) for diagnosis of malignancy in thyroid nodules (TNs) with Bethesda Classification (BC) III or IV indeterminate cytology. METHODS: This preliminary single-center prospective study was approved by the Institutional Review Board. We evaluated 151 consented patients with 151 indeterminate TNs (123 BC III, 28 BC IV) on fine-needle aspiration biopsy (FNAB). B-mode ultrasound, vascularity, and SWE were performed prior to FNAB. TN stiffness was measured as shear wave velocity (SWV) in meters per second (m/s). The stiffest area of the TN was selected for SWV measurement. GEC testing was performed with a second FNAB. Surgery was recommended for GEC-suspicious TNs, or GEC-benign TNs with two or more worrisome B-mode US features. RESULTS: Surgical pathology confirmed 31 malignant TNs. Among the GEC-suspicious group, 28 of 59 TNs were malignant. The SWV value of ≥3.59 m/s was the best cut-off for malignancy risk based on the receiver operating curve (ROC). Twenty-six malignant TNs had SWV ≥ 3.59 m/s. The sensitivity and specificity for SWV ≥ 3.59 m/s were 83.9 and 79.2%, respectively. Positive predictive value (PPV) was 51.0% and negative predictive value (NPV) was 95.0%. For the GEC-suspicious group, sensitivity, specificity, PPV, and NPV were 90.3, 74.2, 47.5, and 96.7%, respectively. In multivariate analysis, SWV and GEC-suspicious were significant predictors of malignancy, but B-mode features and vascularity were not. CONCLUSION: This preliminary study indicates that SWE and GEC are independent predictors of malignancy in TNs with BC III or IV.

Shear wave elastography and parathyroid adenoma: A new tool for diagnosing parathyroid adenomas.

OBJECTIVES: This study prospectively determines the shear wave elastography characteristics of parathyroid adenomas using virtual touch imaging quantification, a non-invasive ultrasound based shear wave elastography method. METHODS: This prospective study examined 57 consecutive patients with biochemically proven primary hyperparathyroidism and solitary parathyroid adenoma identified by ultrasound and confirmed by at least one of the following: surgical resection, positive Technetium-99m Sestamibi Scintigraphy (MIBI) scan, or fine needle aspiration biopsy with positive PTH washout (performed only in MIBI negative patients). Vascularity and shear wave elastography were performed for all patients. Parathyroid adenoma stiffness was measured as shear wave velocity in meters per second. RESULTS: The median (range) pre-surgical value for PTH and calcium were 58pg/mL (19, 427) and 10.8mg/dL (9.5, 12.1), respectively. 37 patients had positive MIBI scan. 20 patients had negative MIBI scan but diagnosis was confirmed with positive PTH washout. 42 patients underwent parathyroidectomy, and an adenoma was confirmed in all. The median (range) shear wave velocity for all parathyroid adenomas enrolled in this study was 2.02m/s (1.53, 2.50). The median (range) shear wave velocity for thyroid tissue was 2.77m/s (1.89, 3.70). The shear wave velocity of the adenomas was independent of adenoma size, serum parathyroid hormone concentration, or plasma parathyroid hormone concentration. CONCLUSIONS: Tissue elasticity of parathyroid adenoma is significantly lower than thyroid tissue. B-mode features and distinct vascularity pattern are helpful tools in diagnosing parathyroid adenoma with ultrasound. Shear wave elastography may provide valuable information in diagnosing parathyroid adenoma.

Shear Wave Elastography and Cervical Lymph Nodes: Predicting Malignancy.

This prospective study evaluates the accuracy of virtual touch imaging quantification (VTIQ), a non-invasive shear wave elastography method for measuring cervical lymph nodes (LN) stiffness in differentiating benign from malignant LN. The study evaluated 270 LN in 236 patients with both conventional B-mode ultrasound and VTIQ shear wave elastography before fine-needle aspiration biopsy (FNAB). LN stiffness was measured as shear wave velocity (SWV) in m/s. Surgical resection was advised for FNAB results that were not clearly benign. Surgical pathology confirmed 54 malignant LN. The receiver operating curve (ROC) identified a single cut-off value of 2.93 m/s as the maximum SWV for predicting a malignant cervical LN. The sensitivity and specificity were 92.59% and 75.46%, respectively. Positive predictive value (PPV) was 48.54% and negative predictive value (NPV) was 97.60%. LN stiffness measured by VTIQ-generated shear wave elastography is an independent predictor of malignancy.

Steroidogenesis and early response gene expression in MA-10 Leydig tumor cells following heterologous receptor down-regulation and cellular desensitization.

The Leydig tumor cell line, MA-10, expresses the luteinizing hormone receptor, a G protein-coupled receptor that, when activated with luteinizing hormone or chorionic gonadotropin (CG), stimulates cAMP production and subsequent steroidogenesis, notably progesterone. These cells also respond to epidermal growth factor (EGF) and phorbol esters with increased steroid biosynthesis. In order to probe the intracellular pathways along with heterologous receptor down-regulation and cellular desensitization, cells were preincubated with EGF or phorbol esters and then challenged with CG, EGF, dibutryl-cyclic AMP, and a phorbol ester. Relative receptor numbers, steroid biosynthesis, and expression of the early response genes, JUNB and c-FOS, were measured. It was found that in all cases but one receptor down-regulation and decreased progesterone production were closely coupled under the conditions used; the exception involved preincubation of the cells with EGF followed by addition of CG where the CG-mediated stimulation of steroidogenesis was considerably lower than the level of receptor down-regulation. In a number of instances JUNB and c-FOS expression paralleled the decreases in receptor number and progesterone production, while in some cases these early response genes were affected little if at all by the changes in receptor number. This finding may indicate that even low levels of activated signaling kinases, e.g. protein kinase A, protein kinase C, or receptor tyrosine kinase, may suffice to yield good expression of JUNB and c-FOS, or it may suggest alternative pathways for regulating expression of these two early response genes.

Thyroid Nodules and Shear Wave Elastography: A New Tool in Thyroid Cancer Detection.

This study determines the performance of virtual touch imaging quantification (VTIQ), a non-invasive shear wave elastography method for measuring thyroid nodule (TN) stiffness, in distinguishing benign from malignant TNs. This prospective study evaluates 707 TNs in 676 patients with fine-needle aspiration biopsy (FNAB). Before FNAB, both conventional B-mode ultrasound and shear wave elastography were performed. Surgical resection was recommended for FNAB results that were not clearly benign. Surgical pathology confirmed 82 malignant TNs. The receiver operating curve identified a single cut-off of 3.54 m/s as the maximum shear wave velocity (SWV) for predicting thyroid cancer (TC). The sensitivity and specificity were 79.27% and 71.52%, respectively. Positive predictive value (PPV) was 26.75% and negative predictive value (NPV) was 96.34%. Compared with B-mode US features for predicting malignancy, SWV ≥3.54 m/s has a higher sensitivity, specificity, PPV and NPV. TN stiffness measured by VTIQ-generated shear wave elastography is an independent predictor of TC.

Electron paramagnetic resonance spectroscopy of nitroxide-labeled calmodulin.

Calmodulin (CaM) is a highly conserved calcium-binding protein consisting of two homologous domains, each of which contains two EF-hands, that is known to bind well over 300 proteins and peptides. In most cases the (Ca(2+))(4-)form of CaM leads to the activation of a key regulatory enzyme or protein in a myriad of biological processes. Using the nitroxide spin-labeling reagent, 3-(2-iodoacetamido)-2,2,5,5-tetramethyl-1-pyrrolidinyl oxyl, bovine brain CaM was modified at 2-3 methionines with retention of activity as judged by the activation of cyclic nucleotide phosphodiesterase. X-band electron paramagnetic resonance (EPR) spectroscopy was used to measure the spectral changes upon addition of Ca(2+) to the apo-form of spin-labeled protein. A significant loss of spectral intensity, arising primarily from reductions in the heights of the low, intermediate, and high field peaks, accompanied Ca(2+) binding. The midpoint of the Ca(2+)-mediated transition determined by EPR occurred at a higher Ca(2+) concentration than that measured with circular dichroic spectroscopy and enzyme activation. Recent data have indicated that the transition from the apo-state of CaM to the fully saturated form, [(Ca(2+))(4-)CaM], contains a compact intermediate corresponding to [(Ca(2+))(2-)CaM], and the present results suggest that the spin probes are reporting on Ca(2+) binding to the last two sites in the N-terminal domain, i.e. for the [(Ca(2+))(2)-CaM] → [(Ca(2+))(4-)CaM] transition in which the compact structure becomes more extended. EPR of CaM, spin-labeled at methionines, offers a different approach for studying Ca(2+)-mediated conformational changes and may emerge as a useful technique for monitoring interactions with target proteins.

Microarray-based transcriptome profiling of ovarian cancer cells.

Transcriptome profiling is a powerful method for monitoring genes and their expression levels under a variety of conditions. Completion of the human genome and advances in high-throughput gene microarray instrumentation enables one to collect large amounts of data in a relatively short time. The challenge then becomes that of data analysis to identify patterns in expression changes and, from there, to relate the observed changes to functional compartments and pathways in cells, tissues, and organisms. Using cultured human ovarian cancer cells as an experimental model cellular system, we describe approaches that are used in analysis of the transcriptome, focusing on those genes encoding proteins and microRNAs. Coupled with other approaches described herein, one can also use the transcriptome to identify potential serum biomarkers, thus providing direction to what usually is a laborious search for low abundance proteins.

Performance of elastography for the evaluation of thyroid nodules: a prospective study.

BACKGROUND: In the ultrasound evaluation of masses, elastography measures stiffness, which may predict malignancy. Studies of small or selected subgroups suggest that elastography may be useful in the evaluation of thyroid nodules (TNs). We prospectively tested the hypothesis that TN stiffness, as measured by strain elastography (SE), is an independent predictor of thyroid cancer (TC) in unselected TNs. METHODS: In 706 unselected patients with 912 TNs meeting the ATA criteria for a fine-needle aspiration biopsy (FNAB), we first performed conventional thyroid ultrasound and SE. Nodule stiffness was graded from least to most stiff by an elastography score (ES) of ES 0 to ES 3. Surgical resection was recommended for FNAB results that were not clearly benign. Bivariate and multivariate regression analyses identified the independent predictors of TC. RESULTS: There were 86 malignant TNs. ES was a significant predictor of TC (p=0.0001). The prevalence of TC was 57 of the 158 TNs (36.1%) for the ES 3 group, 12 of the 158 TNs (7.7%) for the ES 2 group, 16 of the 565 TNs (2.8%) for the ES 1 group, and 1 of the 33 TNs (3%) for the ES 0 group. By multivariate regression analysis, the independent predictors of TC were ES, microcalcifications, hypoechogenicity, and isthmus location. The positive predictive value (PPV) of ES was 36.1%, which was similar to the PPV of microcalcifications (35.9%), but greater compared with hypoechogenicity (13.6%) and isthmus location (16.9%). The negative predictive value (NPV) of ES was 97.2%, which was better than any other predictor for malignancy. CONCLUSIONS: We conclude that TN stiffness measured by elastography is an independent predictor of TC with a PPV that is equal to or greater than that of conventional ultrasonographic characteristics. NPV was greater than any other predictor of malignancy.

A Possible Effect of Concentrated Oolong Tea Causing Transient Ischemic Attack-Like Symptoms.

AIMS: Tea (green, oolong, and black) is the second most widely consumed beverage worldwide, second only to water. Aside from a few reported adverse effects, tea, particularly green tea, appears to be beneficial for human health. In the case described herein, a male experienced several transient ischemic attack-like symptoms immediately following the consumption of a cup of high quality oolong tea. A thorough medical evaluation uncovered no evidence of such an attack and leads to the suggestion of a heretofore unreported response to oolong tea. PRESENTATION OF CASE: A 72-year old male with hypertension and atrial fibrillation, who takes valsartan/hydrochlorothiazide to control hypertension and warfarin to reduce the risk of thrombosis and thromboembolism, presented at the emergency room of a local hospital describing several transient ischemic attack-like symptoms immediately after consuming a cup of oolong tea. His symptoms included presyncope, disequilibrium, bilateral hand parathesias, mild dysphasia, and visual problems (but apparently not presbyopia or amaurosis fugax), all of which had disappeared in approximately two hours after drinking the tea. (Mild presyncope was previously noted by the patient when ingesting a strong green tea.) No unusual features emerged from his physical examination, and his blood work was unremarkable except for elevation of his partial thromboplastin time (39 sec) and prothrombin time (22.5 sec), giving an international reference of 2.0, all consistent with the effects of warfarin. A battery of tests by the emergency room physician, a cardiologist, and a neurologist, e.g. electrocardiogram, brain computerized tomography, 2-dimensional transthoracic echocardiogram, brain magnetic resonance imaging, with and without 20 ml Gadolinium, and a magnetic resonance angiogram, confirmed the earlier diagnosis of atrial fibrillation but disclosed no additional malfunction in his heart. His brain showed no evidence of a prior hemorrhage, and his carotid arteries were clear. METHODOLOGY AND RESULTS: Analysis of the oolong tea by high performance liquid chromatography and mass spectrometry identified the major catechins and two methylxanthines, caffeine and theophylline, as well as other constituents, but there was no evidence of any extraneous chemicals that could lead to the symptoms. CONCLUSION: In view of the rapid onset of symptoms after the consumption of oolong tea, bilateral as opposed to unilateral parathesis, and the absence of any evidence of a hemorrhage or the presence of impurities in the tea, we suggest that the transient ischemic attack-like symptoms could possibly be attributable to one or more components of the oolong tea and was not an atypical magnetic resonance imaging-negative transient ischemic attack.

MicroRNA expression and regulation in human ovarian carcinoma cells by luteinizing hormone.

BACKGROUND: MicroRNAs have been widely-studied with regard to their aberrant expression and high correlation with tumorigenesis and progression in various solid tumors. With the major goal of assessing gonadotropin (luteinizing hormone, LH) contributions to LH receptor (LHR)-positive ovarian cancer cells, we have conducted a genome-wide transcriptomic analysis on human epithelial ovarian cancer cells to identify the microRNA-associated cellular response to LH-mediated activation of LHR. METHODS: Human ovarian cancer cells (SKOV3) were chosen as negative control (LHR-) and stably transfected to express functional LHR (LHR+), followed by incubation with LH (0-20 h). At different times of LH-mediated activation of LHR the cancer cells were analyzed by a high-density Ovarian Cancer Disease-Specific-Array (DSA, ALMAC™), which profiled ∼ 100,000 transcripts with ∼ 400 non-coding microRNAs. FINDINGS: In total, 65 microRNAs were identified to exhibit differential expression in either LHR expressing SKOV3 cells or LH-treated cells, a few of which have been found in the genomic fragile regions that are associated with abnormal deletion or amplification in cancer, such as miR-21, miR-101-1, miR-210 and miR-301a. By incorporating the dramatic expression changes observed in mRNAs, strong microRNA/mRNA regulatory pairs were predicted through statistical analyses coupled with collective computational prediction. The role of each microRNA was then determined through a functional analysis based on the highly-confident microRNA/mRNA pairs. CONCLUSION: The overall impact on the transcriptome-level expression indicates that LH may regulate apoptosis and cell growth of LHR+ SKOV3 cells, particularly by reducing cancer cell proliferation, with some microRNAs involved in regulatory roles.

Regulation of gene expression in ovarian cancer cells by luteinizing hormone receptor expression and activation.

BACKGROUND: Since a substantial percentage of ovarian cancers express gonadotropin receptors and are responsive to the relatively high concentrations of pituitary gonadotropins during the postmenopausal years, it has been suggested that receptor activation may contribute to the etiology and/or progression of the neoplasm. The goal of the present study was to develop a cell model to determine the impact of luteinizing hormone (LH) receptor (LHR) expression and LH-mediated LHR activation on gene expression and thus obtain insights into the mechanism of gonadotropin action on ovarian surface epithelial (OSE) carcinoma cells. METHODS: The human ovarian cancer cell line, SKOV-3, was stably transfected to express functional LHR and incubated with LH for various periods of time (0-20 hours). Transcriptomic profiling was performed on these cells to identify LHR expression/activation-dependent changes in gene expression levels and pathways by microarray and qRT-PCR analyses. RESULTS: Through comparative analysis on the LHR-transfected SKOV-3 cells exposed to LH, we observed the differential expression of 1,783 genes in response to LH treatment, among which five significant families were enriched, including those of growth factors, translation regulators, transporters, G-protein coupled receptors, and ligand-dependent nuclear receptors. The most highly induced early and intermediate responses were found to occupy a network impacting transcriptional regulation, cell growth, apoptosis, and multiple signaling transductions, giving indications of LH-induced apoptosis and cell growth inhibition through the significant changes in, for example, tumor necrosis factor, Jun and many others, supportive of the observed cell growth reduction in in vitro assays. However, other observations, e.g. the substantial up-regulation of the genes encoding the endothelin-1 subtype A receptor, stromal cell-derived factor 1, and insulin-like growth factor II, all of which are potential therapeutic targets, may reflect a positive mediation of ovarian cancer growth. CONCLUSION: Overall, the present study elucidates the extensive transcriptomic changes of ovarian cancer cells in response to LH receptor activation, which provides a comprehensive and objective assessment for determining new cancer therapies and potential serum markers, of which over 100 are suggested.

The extreme C-terminal region of Gαs differentially couples to the luteinizing hormone and beta2-adrenergic receptors.

The mechanisms of G protein coupling to G protein-coupled receptors (GPCR) share general characteristics but may exhibit specific interactions unique for each GPCR/G protein partnership. The extreme C terminus (CT) of G protein α-subunits has been shown to be important for association with GPCR. Hypothesizing that the extreme CT of Gα(s) is an essential component of the molecular landscape of the GPCR, human LH receptor (LHR), and ß(2)-adrenergic receptor (ß(2)-AR), a model cell system was created for the expression and manipulation of Gα(s) subunits in LHR(+) s49 ck cells that lack endogenous Gα(s). On the basis of studies involving truncations, mutations, and chain extensions of Gα(s), the CT was found to be necessary for LHR and ß(2)-AR signaling. Some general similarities were found for the responses of the two receptors, but significant differences were also noted. Computational modeling was performed with a combination of comparative modeling, molecular dynamics simulations, and rigid body docking. The resulting models, focused on the Gα(s) CT, are supported by the experimental observations and are characterized by the interaction of the four extreme CT amino acid residues of Gα(s) with residues in LHR and ß(2)-AR helix 3, (including R of the DRY motif), helix 6, and intracellular loop 2. This portion of Gα(s) recognizes the same regions of the two GPCR, although with differences in the details of selected interactions. The predicted longer cytosolic extensions of helices 5 and 6 of ß(2)-AR are expected to contribute significantly to differences in Gα(s) recognition by the two receptors.

A computational method for prediction of excretory proteins and application to identification of gastric cancer markers in urine.

A novel computational method for prediction of proteins excreted into urine is presented. The method is based on the identification of a list of distinguishing features between proteins found in the urine of healthy people and proteins deemed not to be urine excretory. These features are used to train a classifier to distinguish the two classes of proteins. When used in conjunction with information of which proteins are differentially expressed in diseased tissues of a specific type versus control tissues, this method can be used to predict potential urine markers for the disease. Here we report the detailed algorithm of this method and an application to identification of urine markers for gastric cancer. The performance of the trained classifier on 163 proteins was experimentally validated using antibody arrays, achieving >80% true positive rate. By applying the classifier on differentially expressed genes in gastric cancer vs normal gastric tissues, it was found that endothelial lipase (EL) was substantially suppressed in the urine samples of 21 gastric cancer patients versus 21 healthy individuals. Overall, we have demonstrated that our predictor for urine excretory proteins is highly effective and could potentially serve as a powerful tool in searches for disease biomarkers in urine in general.

Conserved amino acids participate in the structure networks deputed to intramolecular communication in the lutropin receptor.

The luteinizing hormone receptor (LHR) is a G protein-coupled receptor (GPCR) particularly susceptible to spontaneous pathogenic gain-of-function mutations. Protein structure network (PSN) analysis on wild-type LHR and two constitutively active mutants, combined with in vitro mutational analysis, served to identify key amino acids that are part of the regulatory network responsible for propagating communication between the extracellular and intracellular poles of the receptor. Highly conserved amino acids in the rhodopsin family GPCRs participate in the protein structural stability as network hubs in both the inactive and active states. Moreover, they behave as the most recurrent nodes in the communication paths between the extracellular and intracellular sides in both functional states with emphasis on the active one. In this respect, non-conservative loss-of-function mutations of these amino acids is expected to impair the most relevant way of communication between activating mutation sites or hormone-binding domain and G protein recognition regions.

An integrated transcriptomic and computational analysis for biomarker identification in gastric cancer.

This report describes an integrated study on identification of potential markers for gastric cancer in patients' cancer tissues and sera based on: (i) genome-scale transcriptomic analyses of 80 paired gastric cancer/reference tissues and (ii) computational prediction of blood-secretory proteins supported by experimental validation. Our findings show that: (i) 715 and 150 genes exhibit significantly differential expressions in all cancers and early-stage cancers versus reference tissues, respectively; and a substantial percentage of the alteration is found to be influenced by age and/or by gender; (ii) 21 co-expressed gene clusters have been identified, some of which are specific to certain subtypes or stages of the cancer; (iii) the top-ranked gene signatures give better than 94% classification accuracy between cancer and the reference tissues, some of which are gender-specific; and (iv) 136 of the differentially expressed genes were predicted to have their proteins secreted into blood, 81 of which were detected experimentally in the sera of 13 validation samples and 29 found to have differential abundances in the sera of cancer patients versus controls. Overall, the novel information obtained in this study has led to identification of promising diagnostic markers for gastric cancer and can benefit further analyses of the key (early) abnormalities during its development.

A comparative analysis of gene-expression data of multiple cancer types.

A comparative study of public gene-expression data of seven types of cancers (breast, colon, kidney, lung, pancreatic, prostate and stomach cancers) was conducted with the aim of deriving marker genes, along with associated pathways, that are either common to multiple types of cancers or specific to individual cancers. The analysis results indicate that (a) each of the seven cancer types can be distinguished from its corresponding control tissue based on the expression patterns of a small number of genes, e.g., 2, 3 or 4; (b) the expression patterns of some genes can distinguish multiple cancer types from their corresponding control tissues, potentially serving as general markers for all or some groups of cancers; (c) the proteins encoded by some of these genes are predicted to be blood secretory, thus providing potential cancer markers in blood; (d) the numbers of differentially expressed genes across different cancer types in comparison with their control tissues correlate well with the five-year survival rates associated with the individual cancers; and (e) some metabolic and signaling pathways are abnormally activated or deactivated across all cancer types, while other pathways are more specific to certain cancers or groups of cancers. The novel findings of this study offer considerable insight into these seven cancer types and have the potential to provide exciting new directions for diagnostic and therapeutic development.

Functional differences of invariant and highly conserved residues in the extracellular domain of the glycoprotein hormone receptors.

Multiple interactions exist between human follicle-stimulating hormone (FSH) and the N-terminal hormone-binding fragment of the human FSH receptor (FSHR) extracellular domain (ECD). Binding of the other human glycoprotein hormones to their cognate human receptors (luteinizing hormone receptor (LHR) and thyroid-stimulating hormone receptor (TSHR)) was expected to be similar. This study focuses on amino acid residues in ß-strands 2 (Lys(74)), 4 (Tyr(124), Asn(129), and Thr(130)), and 5 (Asp(150) and Asp(153)) of the FSHR ECD identified in the human FSH·FSHR ECD crystal structure as contact sites with the common glycoprotein hormone α-subunit, and on noncontact residues in ß-strands 2 (Ser(78)) and 8 (Asp(224) and Ser(226)) as controls. These nine residues are either invariant or highly conserved in LHR and TSHR. Mutagenesis and functional characterization of these residues in all three human receptors allowed an assessment of their contribution to binding and receptor activation. Surprisingly, the six reported α-subunit contact residues of the FSHR ECD could be replaced without significant loss of FSH binding, while cAMP signaling potency was diminished significantly with several replacements. Comparative studies of the homologous residues in LHR and TSHR revealed both similarities and differences. The results for FSH/FSHR were analyzed on the basis of the crystal structure of the FSH·FSHR ECD complex, and comparative modeling was used to generate structures for domains, proteins, and complexes for which no structures were available. Although structural information of hormone-receptor interaction allowed the identification of hormone-receptor contact sites, functional analysis of each contact site was necessary to assess its contribution to hormone binding and receptor activation.

The luteinizing hormone receptor: insights into structure-function relationships and hormone-receptor-mediated changes in gene expression in ovarian cancer cells.

The luteinizing hormone receptor (LHR), one of the three glycoprotein hormone receptors, is necessary for critical reproductive processes, including gonadal steroidogenesis, oocyte maturation and ovulation, and male sex differentiation. Moreover, it has been postulated to contribute to certain neoplasms, particularly ovarian cancer. A member of the G protein-coupled receptor family, LHR contains a relatively large extracellular domain responsible for high affinity hormone binding; transmembrane activation then leads to G protein coupling and subsequent second messenger production. This review deals with recent advances in our understanding of LHR structure and structure-function relationships, as well as hormone-mediated changes in gene expression in ovarian cancer cells expressing LHR. Suggestions are also made for critical gaps that need to be filled as the field advances, including determination of the three-dimensional structure of inactive and active receptor, elucidation of the mechanism by which hormone binding to the extracellular domain triggers the activation of Gs, clarification of the putative roles of LHR in non-gonadal tissues, and the role, if any, of activated receptor in the development or progression of ovarian cancer.

Determining the affinity of hormone-receptor interaction.

Characterization of the binding of a hormone to its cognate receptor is a cornerstone of many studies in molecular and cellular endocrinology since this event represents the beginning of a specific cellular response, generally from a highly regulated extracellular messenger. The premise of hormone-receptor interaction follows from the law of mass action describing a reversible second-order reaction, hormone plus receptor, to give a non-covalently associated hormone-receptor complex. From this basic principle, a host of useful experimental parameters are available to the interested investigator. This chapter is focused on development of the experimental and mathematical underpinning of hormone-receptor interaction, with emphasis on a gonadotropin, chorionic gonadotropin (or luteinizing hormone), binding to the luteinizing hormone receptor, a member of the G protein-coupled receptor family. The general concepts and approaches developed herein are, however, valid to most interacting systems.