Abstract 3063: A novel mechanism for therapeutic targeting of the glucocorticoid receptor in triple negative breast cancer

Triple negative breast cancer (TNBC) is frequently diagnosed in younger women and is prevalent in African American women. Most TNBCs are highly aggressive with early pattern of metastasis, and with limited treatment options and poor prognosis. Finding effective therapeutic targets for TNBC has proven difficult so far. Therefore, there is an urgent need to develop new and novel therapeutic management of these patients. Recent studies have shown that glucocorticoid receptor (GR) is a mediator of pro-survival genes in TNBC cells, and its expression is predictive of increased risk of metastasis in TNBC tumors and decreased rate of patient survival. Therefore, blocking the effects of GR should be beneficial for TNBC patients. However, GR antagonists such as RU486 (mifepristone) targeting AF2/coactivators have shown only partial success in TNBC cell lines as well as in animal models. Based on our previous data we hypothesize that since in TNBC cells, the GR is constitutively active; therefore, attempts to block/inhibit GR activity through classic antagonists such as mifepristone that bind to ligand binding pocket of the receptor will have a limited clinical efficacy and higher side effects. To circumvent this problem, in this study, we propose a novel and innovative therapeutic approach to target constitutively active AF1 domain of the GR, which exists in an intrinsically disordered (ID) conformation. In this study, we tested our hypothesis that inhibiting/blocking TATA-box binding protein (TBP)-mediated GR’s AF1 activity by our newly identified molecule, PepT will attenuate TNBC cell survival via altering associated endogenous gene expressions. Our binding kinetics of AF1 showed that PepT binds to AF1 with about 10-fold higher affinity when compared with TBP’s binding to AF1. AF1 pre-bound with PepT fails to bind to TBP suggesting that PepT competes and blocks AF1-TBP interaction. We also found that treatment of MDA-MB-231 cells with PepT results in significant attenuation of cell viability and proliferation. Together, these results support our hypothesis that PepT has potential to kill TNBC cells by blocking GR AF1:co-regulator interactions.

Citation Format: Shagufta H. Khan, Christian Carbe, Jun Ling, Raj Kumar. A novel mechanism for therapeutic targeting of the glucocorticoid receptor in triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3063.

Assessment of anthropogenic-causing-agents act on waterbirds-diversity in the vicinity of Tarbela Dam, Indus River, Pakistan

Birds are among the best bio-indicators, which can guide us to recognize some of the main conservation concerns in ecosystems. Anthropogenic impacts such as deforestation, habitat degradation, modification of landscapes, and decreased quality of habitats are major threats to bird diversity. The present study was designed to detect anthropogenic causative agents that act on waterbird diversity in Tarbella Dam, Indus River, Pakistan. Waterbird censuses were carried out from March 2019 to February 2020 in multiple areas around the dam. A total of 2990 waterbirds representing 63 species were recorded. We detected the highest waterbird richness and diversity at Pehure whereas the highest density was recorded at Kabbal. Human activity impacts seemed to be the main factor determining the waterbird communities as waterbirds were negatively correlated with the greatest anthropogenic impacts. Waterbirds seem to respond rapidly to human disturbance.

Study of human knowledge and attitude toward urban birds in Faisalabad city, Pakistan

Birds are very valuable indicators of species richness and endemic patterns in a specified ecosystem, which eventually help the scientist to measure the environmental degradation. The aim of present study was to know human knowledge and attitude toward urban birds in Faisalabad city, Pakistan. The study conducted in four consecutive months: November 2019 to February 2020. Population of birds was noted from eight residential towns of Faisalabad city, data were collected through questionnaire. Faisalabad has a reasonably large population of birds and present data show that, there is a significant difference between favorite bird of residential areas and institutions. The pigeon received the most likeness in bird population among residential area residents, while the myna received the least. The most popular bird in Faisalabad institutions was the sparrow, while the least popular bird was the common myna. Bird adaptation percentage of residential areas and institutional areas of Faisalabad was the highest for parrot and sparrow respectively. People in residential areas and institutions, on the other hand, adapted least to common myna. It is concluded that people of the study area like birds and offered food and high population of birds are present in study area.

Comparison of Outcome of Eclamptic Patient Following Vaginal Delivery versus Caeserian Delivery by Spinal Anaesthesia

Eclampsia is a common problem in pregnancy in Bangladesh. It is a severe form of preeclampsia which affects 5 to 7% of pregnancies is a significant cause of maternal & neonatal morbidity & mortality. Pre-eclampsia when complicated with generalized tonic-clonic convulsions and/or coma is called eclampsia. The term eclampsia is derived from a Greek word, meaning "like a flash of lightening". It may occur quite abruptly, without any warning manifestations. Eclampsia is a major cause of maternal mortality & morbidity as well as foetal loss worldwide, particularly in the third world. Appropriate measures & effective treatment of eclamptic patient in proper time reduce maternal mortality & morbidity. The mainstay of treatment of eclampsia is delivery of the foetus. Two methods are usually applied for delivery of foetus in eclampsia i.e. vaginal delivery & caesarean delivery. This study was done in the department of Gynae & Obs and department of Anaesthesiology, Mymensingh Medical College Hospital from 1st January 2016 to 30th June 2016 to observe the incidence, complications (morbidity) & mortality of eclamptic patients & which method (vaginal delivery versus caesarean delivery by spinal anaesthesia) is safe, better for the eclamptic patients as well as foetal mortality. Successful vaginal delivery is dependant on complex interactions of three variables (3 P) that is power (uterine contraction), passenger (foetus) & passage (birth canal) but power is less effective in eclamptic patient than normal partuents. Vaginal delivery requires prolong times compared with cesarean delivery. Anaesthetic technique is also an important factor for maternal mortality & morbidity of caesarean delivery. Spinal anaesthesia is widely regarded as a reasonable anaesthetic option for caesarean delivery in eclamptic patients. Currently the safety of spinal anaesthesia is well established and it can provide better obstetrical outcome when chosen properly. In this observation caesarean delivery by spinal anesthesia is safer, less complications, less maternal & neonatal mortality than vaginal delivery in eclamptic patients.

Trehalose induced conformational changes in the amyloid-β peptide

Alzheimer's disease is an irreversible and progressive brain disorder featured by the accumulation of Amyloid-β (Aβ) peptide, which forms insoluble assemblies that builds up into plaques resulting in cognitive decline and memory loss. The formation of fibrillar amyloid deposits is accompanied by conformational changes of the soluble Aβ peptide into β-sheet structures. Strategies to prevent or reduce Aβ aggregation using small molecules such as trehalose have shown beneficial effects under in vitro cell- and in vivo mouse- models. However, the role of trehalose in reducing Aβ peptide aggregation is still not clear. In the present study, using circular dichroism- and fluorescence emission- spectroscopies, we demonstrated that in the presence of trehalose, Aβ peptide adopts more helical content and undergoes a disorder/order conformational transition. Based on our findings, we conclude that trehalose affects the conformation of Aβ peptide to form α-helical structure, which may inhibit the formation of β-sheets and thereby aggregation.

Study of Prostatic Volume and its Variations in Different Age Groups of Bangladeshi Cadaver

Benign prostatic hyperplasia and carcinoma of the prostate are the most common disorders of Bangladeshi male in recent years. Volume of the prostate is necessary to estimate the amount of BPH adenoma to determine the appropriate therapy or to select the surgical approach. Transurethral resection of prostate (TURP) is preferred for small glands and open prostatectomy for larger ones. Decrease in prostatic mass after hormonal manipulation or radiation therapy can be used as an indicator of therapeutic efficacy. The effect of prostate volume on biopsy outcome was assessed and was noted that there was an inverse relationship in between size of the gland and prostate cancer. A cross sectional descriptive study was conducted in Department of Anatomy, Mymensingh Medical College, Mymensingh, Bangladesh to find out the difference in volume of the prostate gland of Bangladeshi people in relation to age. The present study was performed on 67 postmortem human prostate gland collected from the morgue in the Department of Forensic Medicine, Mymensingh Medical College by non random purposive sampling technique. The specimens were collected from Bangladeshi cadaver of age ranging from 10 to 80 years. All the specimens were grouped into three categories: Group A (upto 18 years), Group B (19 to 45 years) and Group C (above 45 years) according to age. Dissection was performed according to standard autopsy techniques. The volume of the prostate gland were measured and recorded. The mean volume of the prostate gland was 13.75ml in Group A, 24.44ml in Group B and 29.72ml in Group C. Variance analysis shows that mean differences of volume of the prostate were highly significant among all age groups. The volume of prostate gland was found to be increased with increasing age. For statistical analysis, differences between age groups were analyzed by using students unpaired 't' test. The present study will help to increase the information pool on the volume of prostate gland of Bangladeshi people.

IDENTIFICATION OF QTLs ON CHROMOSOME 1B FOR GRAIN QUALITY TRAITS IN BREAD WHEAT (TRITICUM AESTIVUM L.)

The present study was designed considering the importance of grain quality traits, genetic diversity and marker-trait association analysis in wheat. A significant amount of genetic diversity was found for various seed traits though the genotypes included in the study were found structured. The extent of polymorphism was high with a range of 2-13 alleles and average of 6.5 alleles per locus. Population structure was detected with 30 unlinked SSRs that divided the population of 92 genotypes in three sub-populations. Extensive LD extent was found on chromosome 1B with 42 SSRs specific for 1B chromosome. Marker-trait associations were determined using mixed linear model, where, population structure and kinship calculated on the basis of unlinked markers were covariated with 1B specific markers and traits data. Eight QTLs for five traits including protein, gluten contents, test weight bread and chapati making quality. Protein content, test weight, bread quality and Glu-B1 were found significantly associated with primers WMC419 (32 cM); WMC128 (30 cM), WMC419 (32 cM); WMC818 (17 cM) and WMC416 (44 cM), respectively.

Ambras Syndrome: First Reported Case in Bangladesh and its Oral Rehabilitation

People with rare hypertrichosis syndromes became crowd-drawing money-making phenomena in many 19th century sideshow acts. These individuals have been referred to as dog-men, hair-men, and werewolves. In 1993, Baumister et al. described congenital hypertrichosis lanuginose or Ambras syndrome: a distinct form of congenital hypertrichosis characterized by excessive hair growth over the body and face associated with facial and occasional dental anomalies. Much is not known about this syndrome since fewer than 50 cases have been documented worldwide. In this case report, a nine year old girl presented with excessive hair growth throughout her body that was denser along her midline. Furthermore, her face displayed the typical dysmorphic features characteristic of Ambras syndrome: a round tip nose, thickened nasal cartilage, antiverted nares, prominent philtrum with deep groove, and a trapezoid mouth. Oral examination revealed normal oral mucosa with completely missing and unerupted decidious and permanent teeth. Panoramic radiographs confirmed unerupted deciduous teeth. Previous case reports have mentioned the presence of occasional dental anomalies such as retarded first and second dentition and absence of some teeth. However, this is the first reported case of Ambras syndrome presenting with complete anodontia. Prior cytogenetic studies performed on persons with Ambras syndrome have implicated a balanced pericentric inversion of chromosome 8. However, it is likely that dental anomalies are likely a result of a different genetic rearrangement. Further studies are needed to explore the cause of this rare phenotype of Ambras syndrome with complete unerupted dentition.

Abstract 3305: Glucocorticoid differentially regulates gene expression in luminal and basal subtypes of breast cancer

Steroid hormone receptors (SHRs), such as estrogen- and progesterone- receptors, are well-validated drug targets and prognostic indicators for breast cancer (BC). When targeting SHRs for BC therapy, the major challenge is how to increase the selectivity of drugs against SHRs in specific cell/tissue. While estrogen- and progesterone- receptors are well studied in BC, glucocorticoid (GC) as a ubiquitous stress activated steroid hormone is less investigated. However, the elevated GC circadian dynamics is associated with poor prognosis, and GC receptor (GR) is highly expressed in metastatic BC. GCs are used successfully as an adjuvant therapy to induce apoptosis of leukemia and lymphoma. However, when applied to BC, the results are controversial with most GCs showing either pro-survival or no effects. To analyze the underlying mechanisms, gene expression profiling was performed in this study using qRT-PCR array that covers the genes as the drivers of BC. Our results showed that compared to MCF7 (luminal subtype) cells, MDA-MB-231(basal B subtype) cells are more responsive to Dexamethasone (Dex; a synthetic GC) treatment with the higher number of genes that were either up- or down-regulated. Shared by both MCF7 and MDA-MB-231 cells, the Dex-regulated genes are highly related to cell adhesion and epithelial-mesenchymal transition (EMT), followed by the genes involved in signal transduction, cell division and apoptosis, including SERPIN-E1, CDKN2A, c-Myc, THBS1, Snai2 and E-cadherin. However, the up- and down-regulation patterns are different between MDA-MB-231 and MCF7 cells. Using a real-time label-free cell assay, we identified that Dex promotes MDA-MB-231 cell adhesion and migration but only the spreading for MCF7 cells, suggesting that there are cell-specific effects of GC/GR in different subtypes of breast cancer.

Citation Format: Jun Ling, Zenaida Lopez-Dee, Shagufta H. Khan, Raj Kumar. Glucocorticoid differentially regulates gene expression in luminal and basal subtypes of breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3305. doi:10.1158/1538-7445.AM2014-3305

Regulation of the structurally dynamic N-terminal domain of progesterone receptor by protein-induced folding

The N-terminal domain (NTD) of steroid receptors harbors a transcriptional activation function (AF1) that is composed of an intrinsically disordered polypeptide. We examined the interaction of the TATA-binding protein (TBP) with the NTD of the progesterone receptor (PR) and its ability to regulate AF1 activity through coupled folding and binding. As assessed by solution phase biophysical methods, the isolated NTD of PR contains a large content of random coil, and it is capable of adopting secondary α-helical structure and more stable tertiary folding either in the presence of the natural osmolyte trimethylamine-N-oxide or through a direct interaction with TBP. Hydrogen-deuterium exchange coupled with mass spectrometry confirmed the highly dynamic intrinsically disordered property of the NTD within the context of full-length PR. Deletion mapping and point mutagenesis defined a region of the NTD (amino acids 350-428) required for structural folding in response to TBP interaction. Overexpression of TBP in cells enhanced transcriptional activity mediated by the PR NTD, and deletion mutations showed that a region (amino acids 327-428), similar to that required for TBP-induced folding, was required for functional response. TBP also increased steroid receptor co-activator 1 (SRC-1) interaction with the PR NTD and cooperated with SRC-1 to stimulate NTD-dependent transcriptional activity. These data suggest that TBP can mediate structural reorganization of the NTD to facilitate the binding of co-activators required for maximal transcriptional activation.

Frequency of impaired glucose tolerance and diabetes mellitus in subjects with fasting blood glucose below 6.1 mmol/L (110 mg/dL)

The diagnosis of diabetes mellitus by the available criteria is controversial and relies heavily on fasting glucose results. This cross-sectional study in 2010-2011 aimed to measure the frequency of impaired glucose tolerance and diabetes mellitus in 127 subjects having fasting blood glucose < 7.0 mmol/L and to measure the agreement between different standard diagnostic criteria. Subjects presenting to a laboratory for analysis of fasting blood glucose for excluding diabetes mellitus underwent a 2-hour 75 g oral glucose challenge. A total of 40.6% of subjects with fasting blood glucose from 5.6-6.0 mmol/L had abnormal glucose regulation on the basis ofthe gold standard glucose challenge. Agreement between American Diabetes Association and World Health Organization diagnostic criteria was only fair (kappa = 0.32). Abnormalities of glucose metabolism including impaired glucose tolerance and diabetes mellitus can exist at fasting blood glucose results < 6.1 mmol/L (110 mg/dL).

Binding of the N-terminal region of coactivator TIF2 to the intrinsically disordered AF1 domain of the glucocorticoid receptor is accompanied by conformational reorganizations

Control of gene transcription by glucocorticoid receptors (GRs) is important for many physiological processes. Like other steroid hormone receptors, the regulation of target genes by GR is mediated by two transactivation domains: activation function 1 (AF1) in the N-terminal domain and AF2 in the C-terminal ligand-binding domain (LBD). Full receptor activity requires both AF1 and -2 plus assorted coregulatory proteins. Crystal structures of the ligand-bound LBD have provided insight regarding how AF2 interacts with specific coactivators. However, despite its being the major activation domain of GRs, knowledge of AF1 structure/function has languished. This is mainly because of the highly disorganized structure of the GR N-terminal domain. This lack of AF1 structure is shared by all members of the steroid/nuclear receptor superfamily for which it has been examined and AF1 is thought to allow productive interactions with assorted cofactors via protein-induced changes in secondary/tertiary structures. To date, there are no reports of a classical coactivator altering the secondary/tertiary structure of the GR AF1 domain. Earlier, we reported an N-terminal fragment of the p160 coactivator TIF2, called TIF2.0, that binds the GR N-terminal domain and alters GR transcriptional activity. We therefore proposed that TIF2.0 binding to AF1 changes both its conformation and transcriptional activity. We now report that TIF2.0 interacts with the GR AF1 domain to increase the amount of α-helical structure in the complex. Furthermore, TIF2 coactivator activity is observed in the absence of the GR LBD in a manner that requires the AF1 domain. This contrasts with previous models where TIF2 receptor interaction domains binding to GR LBD somehow alter AF1 conformation. Our results establish for the first time that coactivators can modify the structure of the AF1 domain directly via the binding of a second region of the coactivator and suggest a molecular explanation for how coactivators increase the transcriptional activity of GR-agonist complexes.

Binding-folding induced regulation of AF1 transactivation domain of the glucocorticoid receptor by a cofactor that binds to its DNA binding domain

Intrinsically disordered (ID) regions of proteins commonly exist within transcription factors, including the N-terminal domain (NTD) of steroid hormone receptors (SHRs) that possesses a powerful activation function, AF1 region. The mechanisms by which SHRs pass signals from a steroid hormone to control gene expression remain a central unresolved problem. The role of N-terminal activation function AF1, which exists in an intrinsically disordered (ID) conformation, in this process is of immense importance. It is hypothesized that under physiological conditions, ID AF1 undergoes disorder/order transition via inter- and intra-molecular communications, which allows AF1 surfaces to interact with specific co-regulatory proteins, critical for the final outcome of target gene expression regulated by SHRs. However, the means by which AF1 acquires functionally folded conformations is not well understood. In this study, we tested whether binding of jun dimerization protein 2 (JDP2) within the DNA binding domain (DBD) of the glucocorticoid receptor (GR) leads to acquisition of functionally active structure in its AF1/NTD. Our results show that signals mediated from GR DBD:JDP2 interactions in a two domain GR fragment, consisting of the entire NTD and little beyond DBD, significantly increased secondary/tertiary structure formation in the NTD/AF1. This increased structure formation facilitated AF1's interaction with specific co-regulatory proteins and subsequent glucocorticoid response element-mediated AF1 promoter:reporter activity. These results support the hypothesis that inter- and intra-molecular signals give a functionally active structure(s) to the GR AF1, which is important for its transcriptional activity.

Protein-protein interactions: principles, techniques, and their potential role in new drug development

A vast network of genes is inter-linked through protein-protein interactions and is critical component of almost every biological process under physiological conditions. Any disruption of the biologically essential network leads to pathological conditions resulting into related diseases. Therefore, proper understanding of biological functions warrants a comprehensive knowledge of protein-protein interactions and the molecular mechanisms that govern such processes. The importance of protein-protein interaction process is highlighted by the fact that a number of powerful techniques/methods have been developed to understand how such interactions take place under various physiological and pathological conditions. Many of the key protein-protein interactions are known to participate in disease-associated signaling pathways, and represent novel targets for therapeutic intervention. Thus, controlling protein-protein interactions offers a rich dividend for the discovery of new drug targets. Availability of various tools to study and the knowledge of human genome have put us in a unique position to understand highly complex biological network, and the mechanisms involved therein. In this review article, we have summarized protein-protein interaction networks, techniques/methods of their binding/kinetic parameters, and the role of these interactions in the development of potential tools for drug designing.

The dynamic structure of the estrogen receptor

The estrogen receptor (ER) mediates most of the biological effects of estrogens at the level of gene regulation by interacting through its site-specific DNA and with other coregulatory proteins. In recent years, new information regarding the dynamic structural nature of ER has emerged. The physiological effects of estrogen are manifested through ER's two isoforms, ER_α and ER_β. These two isoforms (ER_α and ER_β) display distinct regions of sequence homology. The three-dimensional structures of the DNA-binding domain (DBD) and ligand-binding domain (LBD) have been solved, whereas no three-dimensional natively folded structure for the ER N-terminal domain (NTD) is available to date. However, insights about the structural and functional correlations regarding the ER NTD have recently emerged. In this paper, we discuss the knowledge about the structural characteristics of the ER in general and how the structural features of the two isoforms differ, and its subsequent role in gene regulation.

TBP binding-induced folding of the glucocorticoid receptor AF1 domain facilitates its interaction with steroid receptor coactivator-1

The precise mechanism by which glucocorticoid receptor (GR) regulates the transcription of its target genes is largely unknown. This is, in part, due to the lack of structural and functional information about GR's N-terminal activation function domain, AF1. Like many steroid hormone receptors (SHRs), the GR AF1 exists in an intrinsically disordered (ID) conformation or an ensemble of conformers that collectively appears to be unstructured. The GR AF1 is known to recruit several coregulatory proteins, including those from the basal transcriptional machinery, e.g., TATA box binding protein (TBP) that forms the basis for the multiprotein transcription initiation complex. However, the precise mechanism of this process is unknown. We have earlier shown that conditional folding of the GR AF1 is the key for its interactions with critical coactivator proteins. We hypothesize that binding of TBP to AF1 results in the structural rearrangement of the ID AF1 domain such that its surfaces become easily accessible for interaction with other coactivators. To test this hypothesis, we determined whether TBP binding-induced structure formation in the GR AF1 facilitates its interaction with steroid receptor coactivator-1 (SRC-1), a critical coactivator that is important for GR-mediated transcriptional activity. Our data show that stoichiometric binding of TBP induces significantly higher helical content at the expense of random coil configuration in the GR AF1. Further, we found that this induced AF1 conformation facilitates its interaction with SRC-1, and subsequent AF1-mediated transcriptional activity. Our results may provide a potential mechanism through which GR and by large other SHRs may regulate the expression of the GR-target genes.

Elucidation of thermotolerance diversity in cotton (Gossypium hirsutum L.) using physio-molecular approaches

Cotton (Gossypium hirsutum) is an important cash crop, but high temperature during its growing season is one of the major factors that limit its productivity. This problem compels plant breeders to breed for heat tolerance, which can help to overcome this challenge. It is very important to make a comprehensive screening of heat-tolerant genotypes so that only the best are chosen. Here we report the combined use of several techniques that can help breeders to screen their germplasm. Twelve cultivated cotton genotypes were evaluated for thermotolerance, using assays that included electrolyte leakage, chlorophyll accumulation and protein profiling, as well as RAPDs to assess genetic diversity. Two genotypes (B-557 and NIAB-78) showed tolerant behavior in three thermotolerance assays. RAPD analysis results showed maximum similarity in a range of 86.7-66.7% between the genotypes MNH-554 and CIM-443. We conclude that combined use should be made of relative electrolyte leakage, chlorophyll stability and differential display with SDS-PAGE to aid in screening for stress tolerance. RAPD-based diversity analysis will further help to improve the efficiency of breeding programs.

Naturally occurring osmolyte, trehalose induces functional conformation in an intrinsically disordered activation domain of glucocorticoid receptor

Intrinsically disordered (ID) regions are frequently found in the activation domains of many transcription factors including nuclear hormone receptors. It is believed that these ID regions promote molecular recognition by creating large surfaces suitable for interactions with their specific protein binding partners, which is a critical component of gene regulation by transcription factors. It has been hypothesized that conditional folding of these activation domains may be a prerequisite for their efficient interaction with specific coregulatory proteins, and subsequent transcriptional activity leading to the regulation of target gene(s). In this study, we tested whether a naturally occurring osmolyte, trehalose can promote functionally ordered conformation in glucocorticoid receptor's major activation function domain, AF1, which is found to exist as an ID protein, and requires an efficient interaction with coregulatory proteins for optimal activity. Our data show that trehalose induces an ordered conformation in AF1 such that its interaction with steroid receptor coactivator-1 (SRC-1), a critical coregulator of glucocorticoid receptor's activity, is greatly enhanced.

Abstract 4532: Induced folding of the glucocorticoid receptor's AF1 domain facilitates its interaction with steroid receptor coactivator-1

The mechanism by which glucocorticoids brings about apoptotic cell death of lymphoid cells is still not well understood. However, it has been established that ligand-activated glucocorticoid receptor (GR) regulates transcription of target genes by binding to site-specific DNA and/or coregulatory proteins. Like other members of the steroid hormone receptors (SHRs), the GR possesses a modular structure characterized by three major functional domains: N-terminal domain (NTD), DNA binding domain (DBD), and ligand binding domain (LBD). The transactivation activity of SHRs is mainly controlled by two activation function domains, AF1 and AF2 located in the NTD and LBD, respectively. The precise mechanism by which SHRs regulate the transcription of the target genes is largely unknown. This is, in part, due to the lack of structural and functional information about AF1 domain. Due to the availability of the LBD structure, the relevant structural and functional properties of AF2 have been well characterized whereas it is nebulous in case of AF1 due to unavailability of its 3-D structure. The GR AF1 exists as an ensemble of largely unstructured conformers or intrinsically disordered (ID). The GR AF1 recruits other coregulatory proteins, including proteins from the basal transcriptional machinery, e.g. TATA box binding protein (TBP) by creating binding surfaces for these proteins. Other studies have also shown that transactivation domains of several transcription factors including SHRs undergo a disorder/order transition upon interaction with proteins from the basal transcriptional machinery. We have earlier shown that conditional folding of the GR AF1 is the key for its interactions with its critical coactivator proteins. It is interesting that the ID GR AF1 directly interacts with the TBP, the critical protein that forms the basis for the multiprotein transcription initiation complex. However, the precise mechanism of this process is unknown. One possibility may be that TBP binding-induced structured conformation in AF1 is involved in creating a platform for the GR AF1-associated coactivators. In this study we tested whether TBP binding induces structure formation in the GR AF1 such that AF1's interaction with SRC-1, a critical coactivator which is important for GR-mediated transcriptional activity, is facilitated. Our data show that TBP binding induced structure formation in the GR AF1facilitates its interaction with SRC-1, and subsequent AF1-mediated transcriptional activity. Our results provide a potential mechanism through which GR and other SHRs may regulate the expression of the GR-target genes, information essential to understand how specific signals are passed from the receptor to target genes.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4532. doi:10.1158/1538-7445.AM2011-4532

Abstract 4552: Naturally occurring osmolyte, trehalose induces a functionally active conformation in an intrinsically disordered transactivation function domain (AF1) of the Glucocorticoid Receptor

Due to the ability of glucocorticoids to prevent the growth and to cause apoptotic death of malignant cells, they are a mainstay of therapy for many lymphomas and leukemias. Glucocorticoid receptor (GR) mediates the biological effects of glucocorticoids at the level of gene regulation. To initiate transcription of target gene(s), GR interacts with its response element DNA, and/or with various coregulatory proteins. However, specific interaction surfaces of GR with its coregulators are not well understood. Consequently, precisely how transcription is regulated by GR is largely unknown. This is due, in part, to the lack of information about GR's major transactivation function region, AF1 located in the N-terminal domain. The major obstacle in determining the structure of AF1 has been due to its intrinsically disordered (ID) conformation, frequently found in the activation domains of many transcription factors, and it is believed that ID nature of these activation domains promote molecular recognition by creating large interaction surfaces suitable for interactions with their specific protein binding partners, which is a critical component of gene regulation by transcription factors. It has been hypothesized that conditional folding of these activation domains may be a prerequisite for their efficient interaction with specific coregulatory proteins, and subsequent transcriptional activity leading to the regulation of target gene(s). In this study, we tested whether a naturally occurring osmolyte, trehalose can promote functionally ordered conformation in the GR's major activation function domain, AF1, which is found to exist as an ID protein, and requires an efficient interaction with coregulatory proteins for optimal activity. Our data show that trehalose induces an ordered conformation in AF1 such that its interaction with steroid receptor coactivator-1 (SRC-1), a critical coregulator of glucocorticoid receptor's activity, is greatly enhanced. Our results may provide a mechanism for cell-type specificity of the effects of GR in gene regulation.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4552. doi:10.1158/1538-7445.AM2011-4552

Role of the androgen receptor CAG repeat polymorphism in prostate cancer, and spinal and bulbar muscular atrophy

Androgens are involved in the development of several tissues, including prostate, skeletal muscle, bone marrow, hair follicles, and brain. Most of the biological effects of the androgens are mediated through an intracellular transcription factor, the androgen receptor (AR) at the level of gene regulation. Several types of mutations in the AR gene have been linked to endocrine dysfunctions. The expansion of CAG codon repeat, coding for a polyglutamine (PolyQ) tract in the N-terminal domain is one such mutation. The polyQ chain length impacts AR's ability to interact with critical coregulators, which in turn modulates its transcriptional efficacy. Pathologic manifestations of variations in polyQ chain length have been associated with prostate cancer susceptibility, and the Spinal and Bulbar Muscular Atrophy (SBMA), a neurodegenerative disease. In this review article, we discuss multiple aspects of the role of polyQ chain length in the actions of the AR, their importance in prostate cancer development and progression, and SBMA with an aim to understand the underlying mechanisms involved in these diseases, which can be targeted for future therapeutic approaches.

Radiology reporting: a general practitioner's perspective

Unlike hospital-based clinicians, general practitioners (GPs) lack direct contact with radiologists, and the radiology report is usually the sole method of communication from the radiologist to the GP. It is important to gain feedback regarding what GPs perceive as a good-quality radiology report, especially in the current climate of competition for provision of radiology services. The aims of this study are to determine the level of GP satisfaction with radiology reports, their perception of optimum report content and their preferences regarding the level of detail and report format. A questionnaire was sent to 100 GPs referring to our Trust for radiology services. GPs were generally satisfied with the content and clarity of reports that they receive, and gave suggestions on how reports could be improved. The majority of GPs were unfamiliar with the normal size ranges of frequently measured anatomical structures. Radiologists' recommendations for further treatment, referral and non-radiological investigation were viewed as valuable report components. When asked to rank preferences for ultrasound reports for the same patient with differing formats and levels of detail, GPs favoured detailed reports in a tabulated format. In conclusion, the majority of GPs like detailed reports and value the radiologist's opinion outside the remit of imaging when suggesting further patient management. Reporting the size of a structure without explanation of its significance can potentially cause confusion. It is important to know if GPs are satisfied with the radiology reports they receive so that we can uphold high communication standards and ultimately improve patient care.

Upper lip swelling caused by a large dentigerous cyst with mesiodens

Swelling of upper lip can results from various diseases such as salivary tumors, infections and inflammatory diseases and cyst, typically involving unerrupted teeth, are sometimes associated with supernumerary teeth in the maxillary anterior incisor region called the mesiodens. Mesiodens with dentigerous cyst is actually a rare case in the world and of course in Bangladesh. The overall prevalence of this type of cyst is only 0.15-1.9% of the total population. Recently we have experienced this kind of case like dentigerous cyst with mesiodens in the department of dentistry, Bangladesh Institute of Research and Rehabilitation in Diabetes, Endocrine and Metabolic Disorders (BIRDEM) Hospital. The patient was 24 years old male young complaining of slow growing painless swelling on the upper lip region for the last several years. Clinical examination revealed a soft intra oral swelling in the labial surface of maxillary incisor region and there was also extra orally upper lip swelling. Radiographic examination demonstrated a large radiolucent area with a mesiodens extending to the root of both lateral incisors. The patient was treated surgically by enucleation of total cysts and surgical extraction of mesiodens under local anesthesia.

Effects of different osmolytes on the induced folding of the N-terminal activation domain (AF1) of the glucocorticoid receptor

In order to understand gene regulation by glucocorticoids, it is pivotal to know how the major transactivation domain AF1 of the glucocorticoid receptor (GR) functions. Located in the N-terminal region of the GR, AF1 is quantitatively important for transcriptional regulation, but only in recent years have we begun to understand how AF1 works. This is in part due to the fact that the recombinant AF1 (rAF1) peptide exists as a random ensemble of conformers. Algorithms that predict structure support the view that AF1 is also not well ordered in the holo-GR, and the properties of the amino acids in AF1 suggest that it is intrinsically disordered. However, it is generally believed that intrinsically disordered sequences of the GR AF1 must achieve one or more ordered conformation(s) to carry out transactivation activity. Based on our previous published work and available literature, we hypothesize that a confluence of effects that operate under physiological conditions cause functionally active conformation(s) to form in AF1. We have shown that when rAF1 is incubated in increasing concentrations of a naturally occurring osmolyte trimethylamine-N-oxide (TMAO), the peptide folds into functionally active conformation(s) that selectively binds several critical coregulatory proteins. Because cells contain various organic osmolytes whose effects may be cumulative, and in light of cell-specific effects of GR AF1 action, we tested whether it can be folded by other natural organic osmolytes representative of three classes: certain amino acids (proline), methylamines (sarcosine), and polyols (sorbitol). The osmolyte-induced folding of rAF1 shows greatly increased affinity for specific binding proteins, including TATA box-binding protein (TBP), CREB-binding protein (CBP), and steroid receptor coactivator-1 (SRC-1). Consistent with theory and published data with other proteins, our results show that different osmolytes have differential effects on rAF1 folding. The cell-specific functions of the GR AF1--and by extension the AF1s of other nuclear hormone receptors--may in part be affected by the presence and concentrations of particular osmolytes within a particular cellular environment.

Pattern of local relapse of maxillary sinus carcinoma

Maxillary sinus carcinoma (MSC) is a rare disease with a variety of treatment options. The present study was undertaken to review the outcome of patients with treated MSC in order to clarify the factors related to local recurrence by analyzing CT findings. The study group comprised of 47 cases, 40 males and 7 females with a median age of 61 years (range, 40- 84 years) treated between 1988 to 1996 at the department of radiotherapy. CT was taken with a slice thickness of 5 mm and contrast material was routinely used. The mean follow-up period for the group was 45.0 months (range, 3-125 months). The treatment policy was either preoperative radiotherapy of 40Gy/16fr followed by maxillectomy or radical radiotherapy of 65Gy/26fr with partial maxillectomy during the course of radiotherapy. By using CT-simulation, wedge pair techniques were used in most patients with Cobalt or 6MV X-ray machines as treatment sources. Tumor extension was categorized into the following anatomical sites: orbital contents, other paranasal sinuses, posterior wall of the maxillary sinus, pterygoid plate/muscle, nasopharynx, infra-temporal fossa, base of the skull, anterior wall of the maxillary sinus, subcutaneous tissue, cheek mucosa, hard palate and alveolar bone. Local control was computed by using the Kaplan-Meier method and p value was measured by using Chi-squared test. The 5-year overall local control rates for all patients were 56%. The local recurrence was found in 19 of 47 patients (40.4%). Tumors extending to pterygoid plates (n=13) and pterygoid muscles (n=10) showed higher rate of local recurrences as compared to those without extensions (9/13 [69%] vs 10/34 [29%], p<0.02 and 7/10 [70%] vs 12/37 [32%], p<0.05, respectively). Extensions to nasopharynx (6/9, 66%) and base of skull (4/6, 66%) also showed higher rates of recurrence; however, those were not statistically significant. More than 80% of the relapse became manifest within 12 months of diagnosis and isolated local failure was the most common pattern. This analysis indicates that tumor extension to pterygoid plate/muscles, results in higher rates of recurrences. This may due to the difficult surgical accessibility of the tumor. During radiotherapy planning, special emphasis should be given to this sites of tumor extension to avoid possible local recurrence.

Expression of FGFR-2 and FGFR-3 in the normal human fetal orbit

AIMS

To demonstrate the expression patterns of two fibroblast growth factor receptors (FGFR-2 and FGFR-3) in the normal human fetal orbit.

METHODS

6 microm orbital slide sections were prepared from 12 week old human fetal material obtained within established ethical guidelines. Radioactive in situ hybridisation techniques were used to demonstrate the expression patterns of FGFR-2 and FGFR-3 within these sections. Only one foetus had appropriate orbital sections taken.

RESULTS

FGFR-2 was expressed within the extraocular muscles (EOMs) and the optic nerve sheath and to a lesser degree within the orbital periosteal margins and the cranial sutures. FGFR-3 was expressed a lot within the periosteal margins and cranial sutures but not within either the EOMs or the optic nerve sheath.

CONCLUSIONS

FGFR-2 and FGFR-3 are differentially expressed within different orbital components. FGFR-2 gene mutations may be responsible for craniosynostotic syndromes such as Crouzon, Pfeiffer, and Apert, while those in the FGFR-3 gene may cause isolated unicoronal synostosis. EOMs may be histologically abnormal in cases of Apert, Pfeiffer, and Crouzon syndromes but not isolated unicoronal synostosis. The pattern of expression of FGFR-2 in the normal human fetal orbit may explain some of the EOM histological findings seen in some cases of Apert, Pfeiffer, and Crouzon syndromes.

In vitro conjugation of ethanolamine with fatty acids by rat liver subcellular fractions

Previous studies from our laboratory have shown the enzymic formation of fatty acid (FA) conjugates of xenobiotic alcohols and amines. In the present study, the formation of FA conjugates of a bifunctional compound, ethanolamine was investigated by incubating [1-14C]oleic acid (1 mM) with ethanolamine (25 mM) at 37 degrees C in the presence of various rat liver subcellular fractions. The resultant product (or products) was separated by thin-layer chromatography (TLC) and the radioactivity corresponding to the relative flow of fatty acid amide was determined. Under similar conditions, formation of ethanolamides of palmitic, stearic, linoleic, linolenic, and arachidonic acids were also examined. The formation of ethanolamine conjugate with oleic acid was found to be 16.3 nmol/h/mg protein as compared to 6.7, 6.2, 8.1, 8.3, and 7.6 nmol/h/mg protein for palmitic, stearic, linoleic, linolenic, and arachidonic acids, respectively. The formation of oleoyl ethanolamide was found to be 18.9, 40.1, 65.9, and 0.3 nmol/h/mg protein in postnuclear, mitochondrial, microsomal, and cytosolic fractions, respectively. Mass spectrometric and nuclear magnetic resonance spectroscopic data of the TLC-purified product confirm the formation of oleoyl ethanolamide, and amidation appeared to be a preferred reaction over esterification. The results of this study suggest that the enzyme responsible for the amidation of fatty acids resides mainly in the microsomal fraction of the liver, and that oleic acid is a better substrate than other fatty acids used in the present study.

Antiischemic effects of topiramate in a transient global forebrain ischemia model: a neurochemical, histological, and behavioral evaluation

The mechanisms of action of the anticonvulsant topiramate (TPM) are indicative of a potential benefit during cerebral ischemia. TPM was studied in a transient global forebrain ischemia (TGFI) model in gerbils in which 40 mg/kg was administered before or after TGFI. Control groups were administered 0.9% normal saline similarly. The evaluation consisted of neurochemical, histological, and functional analyses. The data obtained indicates that unlike the focal cerebral ischemia model, TPM is not neuroprotective in TGFI. The difference in effect, which may be due to the difference in species or the type of ischemia, points to the need for caution when extrapolating animal data from this drug to humans.

Visual outcomes and amblyogenic risk factors in craniosynostotic syndromes: a review of 141 cases

AIMS

To determine the visual outcome and prevalence of amblyogenic risk factors in children with craniosynostotic syndromes.

METHODS

The case notes of 141 children seen within the craniofacial unit were reviewed and information retrieved on date of birth, age at first and last examination, cycloplegic refraction at last visit, best corrected visual acuity at last visit, horizontal ocular deviation in primary position at first visit, and alphabet pattern if any. The presence of astigmatism, its magnitude, and orientation of axis were determined.

RESULTS

40.3% of patients had 1 dioptre (D) of astigmatism or greater and, of these, 64% had oblique astigmatism in at least one eye. Anisometropia of 1D or more was found in 18% of patients (age matched normals 3.5%). Horizontal strabismus was found in 70% (38% exotropia, 32% esotropia). Visual outcome results showed 39.8% of patients (45 of 113) had visual acuity of 6/12 or worse in their better eye.

CONCLUSION

In the largest study to date a poor visual outcome was shown in children with Crouzon's, Pfeiffer's, Apert's, and Saethre-Chotzen syndromes (39.8% with 6/12 or worse in the better eye) together with significant prevalence of amblyogenic risk factors.

The technique of intracerebral microdialysis

Intracerebral microdialysis is an increasingly popular experimental technique. A brief description of the principles of microdialysis is presented and the terms relevant to the procedure are defined. The methodology involved in conducting intracerebral microdialysis is described in detail. Factors influencing the outcome of analysis such as external stimuli, perfusion fluid, perfusion rate, temperature, probe placement, membrane characteristics, and timing of sample collection are discussed. The importance of maintaining the uniformity of the above-mentioned factors is stressed.

Mechanisms involved in the potentiation of melphalan by the bioreductive compound THNLA-1 in vitro

9-[3-(2-Nitro-1-imidazolyl)propylamino]-1,2,3,4-tetrahydroacridine hydrochloride (THNLA-1) is a 2-nitroimidazole-based, weakly DNA-intercalating bioreductive agent that significantly potentiates the toxic effects of commonly used antitumor drugs such as melphalan (L-PAM) or cis-DDP in sensitive or resistant cell lines in culture, as well as in solid tumors in mice. Potentiation in vitro was observed when cells were preexposed to THNLA-1 under hypoxic conditions before exposure to L-PAM under aerobic conditions. In this study we investigated possible mechanisms involved in the potentiation of L-PAM by THNLA-1 in V79 Chinese hamster cells. Limited depletion of glutathione with buthionine sulfoximine or THNLA-1 under hypoxic pretreatment conditions accounted for only 8.3% of the potentiation induced by THNLA-1. However, DNA, RNA, and protein synthesis were inhibited in a synergistic way in cells preexposed to THNLA-1 under hypoxic conditions (2 h, 37 degrees C) and then coexposed to various doses of L-PAM under aerobic conditions (1 h, 37 degrees C). Cell cycle analysis by flow cytometry showed a slow traverse through the S phase in the L-PAM-alone-treated cells. However, this phenomenon was more prominent in the THNLA-1 plus L-PAM-treated cells. Under aerobic co-incubation conditions with L-PAM, no difference was observed in the cell cycle of L-PAM-alone-treated cells vs. THNLA-1 plus L-PAM-treated cells. Significantly increased apoptosis was observed in the hypoxia-pretreated cells with THNLA-1, 12 and 24 h posttreatment. Comet and alkaline elution assay analysis showed increased DNA cross-links in the hypoxia-pretreated cells with THNLA-1 compared to the L-PAM-alone-treated cells. Finally, potential lethal damage repair was totally suppressed only in the hypoxia-pretreated cells with THNLA-1. In conclusion, DNA damage and hindrance in its repair are the most important mechanisms in the potentiation of L-PAM by THNLA-1, under hypoxic pretreatment conditions.

Tibial plateau fractures. A new classification scheme

Fractures of the tibial plateaus are common injuries. Various classification schemes have been used to describe these injuries. Although each system has its own purpose, the simpler systems do not allow comparison with more complex divisions. The problem is compounded by the variable use of adjectives that describe these fractures. A comprehensive classification of tibial plateau fractures should group fractures that are similar in topography, morphology, and pathogenesis, requiring similar treatment, and having a similar prognosis. Fracture dislocations and standard tibial plateau fractures should be incorporated into a single classification to avoid the use of two complementary classifications. Any such classification should not be difficult to remember or to use. Keeping in mind these requirements, the authors devised a simple yet comprehensive classification. The authors studied 80 cases of tibial plateau fractures from January 1988 to September 1997, and used contemporary classifications of tibial plateau fractures as a database to formulate the new classification. A new fracture, subcondylar bicondylar with coronal split, has been classified for the first time. An alphanumeric system has been developed that has made nomenclature easy to remember and use. An effort has been made to address the profoundly confusing issue of variable adjectives that describe these injuries. A review of the literature shows that fractures in the authors' classification have been grouped according to similar pathomechanics, treatment, and functional results.