A Single-Institution Review of the Use of Radiation in the Adjuvant and Definitive Management of Keloids

AIMS

Many individuals suffer from keloids that are refractory to standard treatment modalities, including surgical excision alone. Radiation therapy can be used to reduce the risk of recurrent keloids post-operatively, as well as be used as primary treatment for keloids not amenable to surgical resection. The purpose of this study was to review our institutional experience of radiation therapy for keloid management.

MATERIALS AND METHODS

A retrospective review of patients treated with radiation therapy for keloids between 2014 and 2020 at our institution was performed.

RESULTS

A total of 70 keloids in 41 patients were treated. For the 55 keloids treated with post-operative radiation therapy (16Gy delivered in 2 fractions), 82.5% (33/40) of evaluable lesions did not recur. Among the 15 keloids treated with definitive radiation therapy (24Gy delivered in 3 fractions), 78.6% (11/14) of evaluable keloids showed complete flattening, and 14.3% (2/14) had partial flattening. Both acute and late toxicities were mild, with only a single instance of grade 3 toxicity (dermatitis).

CONCLUSION

Our study confirms that radiation therapy has a role in reducing the risk of keloid recurrence post-operatively, and plays an important role in the definitive management of unresectable keloids.

HDAC3 and HDAC8 PROTAC dual degrader reveals roles of histone acetylation in gene regulation

HDAC3 and HDAC8 have critical biological functions and represent highly sought-after therapeutic targets. Because histone deacetylases (HDACs) have a very conserved catalytic domain, developing isozyme-selective inhibitors remains challenging. HDAC3/8 also have deacetylase-independent activity, which cannot be blocked by conventional enzymatic inhibitors. Proteolysis-targeting chimeras (PROTACs) can selectively degrade a target enzyme, abolishing both enzymatic and scaffolding function. Here, we report a novel HDAC3/8 dual degrader YX968 that induces highly potent, rapid, and selective degradation of both HDAC3/8 without triggering pan-HDAC inhibitory effects. Unbiased quantitative proteomic experiments confirmed its high selectivity. HDAC3/8 degradation by YX968 does not induce histone hyperacetylation and broad transcriptomic perturbation. Thus, histone hyperacetylation may be a major factor for altering transcription. YX968 promotes apoptosis and kills cancer cells with a high potency in vitro. YX968 thus represents a new probe for dissecting the complex biological functions of HDAC3/8.

Prognostic Value of Tumor Volume Reduction during Radiotherapy in Patients with Locally Advanced Cervical Cancer in Different Risk Groups

PURPOSE/OBJECTIVE(S)

To evaluate the risk factors of patients with locally advanced cervical cancer (LACC) undergoing radical radiotherapy (with or without concurrent chemotherapy) and to assess the prognostic value of tumor volume regression (TVR) based on magnetic resonance imaging (MRI) in different risk groups.

MATERIALS/METHODS

A retrospective analysis was performed on 176 individuals diagnosed with stage IIA-IVA cervical cancer (CC) who underwent radical intensity-modulated radiotherapy in our center between January 2012 and December 2020. The tumor volume before radiotherapy (TVp) and before brachytherapy (TVmid) were evaluated based on three-dimensional MRI images, TVR = (TVp -TVmid)/TVp × 100%. Kaplan-Meier curves were used to assess patient's overall survival (OS) and progression-free survival (PFS). Prognostic factors were identified using Cox proportional hazards models.

RESULTS

For the entire cohort, patients with TVR ≥ 94% had better 5-year OS (82.7% vs 49.8%, p<0.001) and 5-year PFS (82.5% vs 51.1%, p<0.001) compared to TVR < 94%. Patients with TVR ≥ 94% were more likely to receive concurrent chemoradiotherapy (CCRT) than those with TVR < 94% (70.1% vs 40.5%, p<0.05). Among patients undergoing CCRT, those with a TVR ≥ 94% had a better prognosis than those with a TVR < 94%. However, among patients who received RT alone, those with TVR ≥ 94% had better PFS but no statistically significant difference in OS. Likewise, among patients with CYFRA21-1 < 7.7 ng/ml, patients with TVR ≥ 94% had a better prognosis. However, TVR was not a prognostic factor in patients with CYFRA21-1 ≥ 7.7 ng/ml. Both CYFRA21-1 (OS, PFS interaction, p<0.001) and FIGO stage (PFS interaction, p = 0.035) were found to significantly impact predictive effects of TVR.

CONCLUSION

In LACC patients with CRYFA21-1 < 7.7 ng/ml who received CCRT, TVR was an important prognostic factor. However, in patients with CRYFA21-1 ≥ 7.7 ng/ml who received RT alone, the prognostic value of TVR needs to be further explored.

Management and Outcomes of Hodgkin Lymphoma Patients Who Achieve Partial Metabolic Response on PET Scans Post-Chemotherapy

PURPOSE/OBJECTIVE(S)

Optimal management of patients with Hodgkin Lymphoma (HL) who do not achieve PET (positron emission tomography) complete metabolic response after primary systemic therapy is unclear. Options vary significantly and include radiation therapy (RT) to localized sites of PET avid disease, salvage chemotherapy followed by autologous stem-cell transplantation (ASCT), or observation with serial imaging. This multi-center study sought to investigate the management approaches and outcomes for HL patients who achieved partial metabolic response after primary systemic therapy.

MATERIALS/METHODS

In this retrospective study, patients diagnosed with HL were identified from the electronic medical records database of two large academic centers between January 2009 and September 2021. PET scan results following initial chemotherapy were reviewed and responses were categorized using International Working Group (IWG) criteria, with the initial staging imaging being used as the reference against which response was evaluated. We performed descriptive analysis of demographic and clinical characteristics of the population and Kaplan-Meier estimates were used to determine progression-free survival (PFS).

RESULTS

The charts of 1,093 HL patients were reviewed. A total of 765 patients had a post chemotherapy PET scan with 57 of those showing partial metabolic response. Among these 57 patients, 31 (54%) were male, the median age at diagnosis was 31 (range:18-74), and the median length of follow up was 1.6 years (average 2.9 years). Five percent stage I, 32% stage II, 23% stage III, and 40% stage IV. Typical initial chemotherapy included ABVD, ABVD switched to BEACOPP due to abnormal interim PET, and AVD with Brentuximab. Among all patients with metabolic partial response to chemotherapy, the 2-year PFS was 72.8% (95% CI = 60.9-87%). Thirty-three of these patients (58%) were treated with planned radiation therapy alone, and 2-year PFS was 80.7% (95% CI = 66.6-97.9%). For those who did not receive radiation as part of their treatment, progression rate was 38% at 2 years.

CONCLUSION

To our knowledge, this is the largest series of HL patients with partial metabolic response following primary chemotherapy. Our preliminary analysis showed that treatment with radiation was associated with good PFS at 2 years and many of those treated with radiation alone were cured.

Reduced prescription of TNF-inhibitors in chronic arthritis based on therapeutic drug monitoring: A randomized controlled trial

OBJECTIVE

Dosing of tumour necrosis factor-α inhibitors (TNFis) is not personalized causing interindividual variation in serum drug levels; however, dose optimization is not widely implemented. We hypothesized that some patients are overdosed; thus, drug prescription could be reduced by therapeutic drug monitoring (TDM).

METHOD

Independent of disease activity, 239 adults treated for rheumatoid arthritis (n = 99), psoriatic arthritis 15 (n = 48), or spondyloarthritis (n = 92) were recruited for a 48-week prospective, randomized open-label trial. Standard care alone or plus TDM was applied in chronic arthritis patients treated with infliximab (IFX), (n = 81), etanercept (ETN) (n = 79), or adalimumab (ADA) (n = 79). Serum TNFi trough levels assessed at inclusion and every 4 months determined patients within/outside predefined therapeutic intervals, supporting change in prescription or drug switch. The primary endpoint was reduced drug prescription.

RESULTS

Compared to standard care, TDM reduced prescribed IFX [-12% (95% confidence interval -20, -3); p = 0.001] and ETN (-15% (-29, 1); p = 0.01], and prolonged the interdosing intervals of ETN [+235% (38, 432); p = 0.02] and ADA [+28% (6, 51); p = 0.04]. Time to drug switch was accelerated (χ2 = 6.03, p = 0.01). No group differences in adverse events, disease activity, or self-reported outcomes were shown, indicating equally sustained remission.

CONCLUSIONS

TDM reduced prescription of IFX, ETN, and ADA and identified patients benefiting from accelerated drug switch, thereby minimizing treatment failure, risk of toxicity, and unnecessary adverse events.

DAXX drives de novo lipogenesis and contributes to tumorigenesis

Cancer cells exhibit elevated lipid synthesis. In breast and other cancer types, genes involved in lipid production are highly upregulated, but the mechanisms that control their expression remain poorly understood. Using integrated transcriptomic, lipidomic, and molecular studies, here we report that DAXX is a regulator of oncogenic lipogenesis. DAXX depletion attenuates, while its overexpression enhances, lipogenic gene expression, lipogenesis, and tumor growth. Mechanistically, DAXX interacts with SREBP1 and SREBP2 and activates SREBP-mediated transcription. DAXX associates with lipogenic gene promoters through SREBPs. Underscoring the critical roles for the DAXX-SREBP interaction for lipogenesis, SREBP2 knockdown attenuates tumor growth in cells with DAXX overexpression, and DAXX mutants unable to bind SREBP1/2 have weakened activity in promoting lipogenesis and tumor growth. Remarkably, a DAXX mutant deficient of SUMO-binding fails to activate SREBP1/2 and lipogenesis due to impaired SREBP binding and chromatin recruitment and is defective of stimulating tumorigenesis. Hence, DAXX's SUMO-binding activity is critical to oncogenic lipogenesis. Notably, a peptide corresponding to DAXX's C-terminal SUMO-interacting motif (SIM2) is cell-membrane permeable, disrupts the DAXX-SREBP1/2 interactions, and inhibits lipogenesis and tumor growth. These results establish DAXX as a regulator of lipogenesis and a potential therapeutic target for cancer therapy.

Abstract 5347: Selective targeting deacetylase 3 (HDAC3) and HDAC8 by PROTACs

Histone deacetylases (HDACs) are enzymes that play an essential role in multiple cellular processes such as DNA transcription, translation, replication, recombination, repair, and metabolism, and their dysregulation can be linked to many different diseases. Most commonly, the overexpression of HDACs is found in various cancer types including hematologic cancers, as well as solid malignancies. Of the many HDACs found in the body, class I HDACs, which consist of HDACs 1, 2, 3, and 8, play an essential role in activating oncogenes underlying tumorigenesis, disease progression, and treatment resistance. Several HDAC inhibitors (HDACis) have been approved for cancer treatment, however, they are pan-inhibitors. This lack of specificity poses many disadvantages for HDACis, including toxicity and other off-target effects. Isozyme-selective inhibitors may reduce these off-target effects and thus enhance their safety. Though favorable, selectivity is difficult to achieve from conventional inhibitors due to the highly homologous catalytic domain among HDAC isozymes. In addition, several HDAC isozymes have deacetylase-independent scaffolding functions that cannot be blocked by traditional inhibitors. Recently, there have been advances in Proteolysis Targeting Chimera (PROTAC), an emerging drug discovery technology designed to hijack cell’s existing protein degradation machinery, the ubiquitin-proteasome system (UPS) to selectively degrade target proteins. Selective degradation by PROTAC is a potential solution to many of the concerns associated with current HDACis. Previously, we reported an HDAC3-selective PROTAC, XZ9002, and following that we reported the discovery of PROTAC YX968, which can degrade both HDAC3 and HDAC8 isozymes with single-digit nanomolar DC50, this highly potent dual degrader exhibits distinct effects on modulating gene expression and is much more potent in inhibiting cancer cell proliferation compared to XZ9002. Based on this, we are further modifying the PROTACs to be selective for HDAC8. The HDAC3, HDAC8 selective degrader and HDAC3 and HDAC8 dual degrader we developed could be useful chemical probes to dissect the complex biological function of HDAC3 and HDAC8 and potential therapeutics for treating cancer.

Citation Format: Yufeng Xiao, Seth Hale, Nikee Awasthee, Xuan Zhang, Yi Liu, Zhiguang Huo, Dongwen Lyu, Lei Wang, Weizhou Zhang, Megan Mosteiro, Daiqing Liao, Guangrong Zheng. Selective targeting deacetylase 3 (HDAC3) and HDAC8 by PROTACs. [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 5347.

Abstract LB138: DAXX interacts with sterol regulatory element-binding proteins (SREBPs) to promote oncogenic lipogenesis and tumorigenesis in triple-negative breast cancer

Elevated lipid metabolism including lipogenesis is a major metabolic feature in cancer cells. In breast and other cancer types, genes involved in lipogenesis are highly upregulated, but the mechanisms that control their expression remain poorly understood. DAXX modulates gene expression through binding to numerous transcription factors although the functional impact of these diverse interactions remains to be defined. Our recent analysis indicates that DAXX is overexpressed in diverse cancer types and metastases. However, mechanisms underlying DAXX’s oncogenic function remains elusive. Using global integrated transcriptomic and lipidomic analyses, we show that DAXX plays a key role in lipid metabolism in triple-negative breast cancer (TNBC) cells. DAXX depletion attenuates, while its overexpression enhances, lipogenic gene expression, lipid synthesis and tumor growth. Mechanistically, DAXX interacts with SREBP1 and SREBP2 and activates SREBP-mediated transcription. DAXX associates with lipogenic gene promoters through SREBPs. Underscoring the critical roles for the DAXX-SREBP interaction for lipogenesis, SREBP2 knockdown attenuates tumor growth in cells with DAXX overexpression, and a DAXX mutant unable to bind SREBPs are incapable of promoting lipogenesis and tumor growth. In TNBC patients, DAXX expression levels are increased in breast cancer brain metastasis and correlate with poor patient survival. Our results identify the DAXX-SREBP axis as an important pathway for tumorigenesis in TNBC. (This work is supported by Florida Department of Health Grants.)

Citation Format: Iqbal Mahmud, Guimei Tian, Tarun Hutchison, Brandon Kim, Daiqing Liao. DAXX interacts with sterol regulatory element-binding proteins (SREBPs) to promote oncogenic lipogenesis and tumorigenesis in triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB138.

[Application of indocyanine green fluorescence visualization in surgical resection of abdominal wall endometriosis]

Objective: To investigate the feasibility, effectiveness and safety of indocyanine green (ICG) navigation in the surgical resection of abdominal wall endometriosis (AWE). Methods: Seven women undergoing surgery for AWE in First Affiliated Hospital of Sun Yat-sen University (from July 1, 2021 to October 1, 2021) were collected. After exposure of the focus, ICG were used intravenously (0.25 mg/kg) as fluorescent dye for the intraoperative evaluation of AWE vascularization. Resection of the AWE was guided by direct visualization of the focus under standard laparoscopy with a near-infrared (NIR) camera head. Surgical margin around the AWE (3, 6, 9 and 12 point) and the margin under the focus were obtained for postoperative pathological examination of endometriosis. Time from injection to fluorescence visualization, the proportion of fluorescence visualization, time of fully resection of AWE, side effects related to the use of ICG, perioperative complications as well as the pathological result of the surgical margins were recorded. Results: ICG fluorescence of the AWE were seen in 5 patients (5/7). The mean time from injection to fluorescence visualization was (46.7±9.8) s. The mean time of fully resection of AWE was (16.4±7.0) minutes. There were no side effects related to the use of ICG. The rate of class-A wound healing was 7/7. All of the surgical margins were confirmed endometriosis-negative by postoperative pathological examination. Conclusion: ICG fluorescence visualization could conduct accurate resection of AWE, which is clinically safe and effective.

CBP/p300: Critical Co-Activators for Nuclear Steroid Hormone Receptors and Emerging Therapeutic Targets in Prostate and Breast Cancers

The CREB-binding protein (CBP) and p300 are two paralogous lysine acetyltransferases (KATs) that were discovered in the 1980s-1990s. Since their discovery, CBP/p300 have emerged as important regulatory proteins due to their ability to acetylate histone and non-histone proteins to modulate transcription. Work in the last 20 years has firmly established CBP/p300 as critical regulators for nuclear hormone signaling pathways, which drive tumor growth in several cancer types. Indeed, CBP/p300 are critical co-activators for the androgen receptor (AR) and estrogen receptor (ER) signaling in prostate and breast cancer, respectively. The AR and ER are stimulated by sex hormones and function as transcription factors to regulate genes involved in cell cycle progression, metabolism, and other cellular functions that contribute to oncogenesis. Recent structural studies of the AR/p300 and ER/p300 complexes have provided critical insights into the mechanism by which p300 interacts with and activates AR- and ER-mediated transcription. Breast and prostate cancer rank the first and forth respectively in cancer diagnoses worldwide and effective treatments are urgently needed. Recent efforts have identified specific and potent CBP/p300 inhibitors that target the acetyltransferase activity and the acetytllysine-binding bromodomain (BD) of CBP/p300. These compounds inhibit AR signaling and tumor growth in prostate cancer. CBP/p300 inhibitors may also be applicable for treating breast and other hormone-dependent cancers. Here we provide an in-depth account of the critical roles of CBP/p300 in regulating the AR and ER signaling pathways and discuss the potential of CBP/p300 inhibitors for treating prostate and breast cancer.

Pharmacological Inhibition of CBP/p300 Blocks Estrogen Receptor Alpha (ERα) Function through Suppressing Enhancer H3K27 Acetylation in Luminal Breast Cancer

Estrogen receptor alpha (ER) is the oncogenic driver for ER+ breast cancer (BC). ER antagonists are the standard-of-care treatment for ER+ BC; however, primary and acquired resistance to these agents is common. CBP and p300 are critical ER co-activators and their acetyltransferase (KAT) domain and acetyl-lysine binding bromodomain (BD) represent tractable drug targets, but whether CBP/p300 inhibitors can effectively suppress ER signaling remains unclear. We report that the CBP/p300 KAT inhibitor A-485 and the BD inhibitor GNE-049 downregulate ER, attenuate estrogen-induced c-Myc and Cyclin D1 expression, and inhibit growth of ER+ BC cells through inducing senescence. Microarray and RNA-seq analysis demonstrates that A-485 or EP300 (encoding p300) knockdown globally inhibits expression of estrogen-regulated genes, confirming that ER inhibition is an on-target effect of A-485. Using ChIP-seq, we report that A-485 suppresses H3K27 acetylation in the enhancers of ER target genes (including MYC and CCND1) and this correlates with their decreased expression, providing a mechanism underlying how CBP/p300 inhibition downregulates ER gene network. Together, our results provide a preclinical proof-of-concept that CBP/p300 represent promising therapeutic targets in ER+ BC for inhibiting ER signaling.

Maintenance treatment in advanced HER2-negative gastric cancer

Survival for patients with advanced gastric cancer (GC) remains poor. Systemic chemotherapy which has reached a plateau stays the standard first-line (1L) treatment for advanced human epidermal growth-factor receptor 2 (HER2)-negative GC. To maximize the benefit of 1L treatment, the concept of maintenance treatment is constantly being explored. In advanced HER2-negative GC, current clinical guidelines do not recommend a standard maintenance therapy strategy. In addition to the monotherapy maintenance with fluorouracil after 4-6 cycles of 1L chemotherapy, some agents that are active against novel targets have been evaluated in clinical trials for maintenance treatment. Whereas most of these trials do not reach their primary endpoints, they open new horizons for the 1L treatment of advanced HER2-negative GC. Therefore, we reviewed the clinical trials in the field of maintenance treatment in advanced HER2-negative GC and discussed some of the problems in clinical trials.

Discovery of histone deacetylase 3 (HDAC3)-specific PROTACs

Histone deacetylases (HDACs) are validated drug targets for cancer treatment. Increased HDAC isozyme selectivity and novel strategies to inhibit HDAC activity could lead to safer and more effective drug candidates. Nonetheless, it is quite challenging to develop isozyme-specific HDACi due to the highly conserved catalytic domain. We discovered XZ9002, a first-in-class HDAC3-specific PROTAC that potently degraded HDAC3. Importantly, XZ9002 is more effective to inhibit cancer cell proliferation than its proteolysis-inactive counterpart, suggesting HDAC3 degradation is a novel and promising anticancer approach.

Abstract 4669: Pharmacologic inhibition of CBP/p300 suppresses estrogen-induced gene expression and proliferation in ER+ luminal breast cancer cells

Luminal breast cancer, defined by the expression of the estrogen receptor alpha (ERα), comprises nearly two thirds of all breast cancer cases and most patients with breast cancer die of this subtype. ERα is a steroid nuclear receptor that functions as a transcription factor to upregulate genes such as MYC that are involved in cell cycle progression. Antagonists of ERα are the standard of care treatment for ER+ luminal breast cancer, but resistance to these antagonists in advanced patients is a major clinical issue. Therefore, there is an unmet medical need to develop more effective therapies for treating ER+ breast cancer. CBP/p300 are two paralogous acetyltransferases that catalyze histone acetylation at enhancers and promoters to activate gene expression. They serve as transcriptional co-activators for several oncogenic signaling pathways, including the pro-growth androgen and estrogen signaling pathways in cancer. Due to their emerging role in promoting tumor growth, the oncogenic functions of CBP/p300 and means of their pharmacologic inhibition are under intense investigation for developing potential therapeutics for cancer treatment. CBP/p300's acetyltransferase (HAT) domain and their bromodomain represent tractable drug targets and potent and specific small molecule inhibitors have been developed for both. However, the pharmacologic effects and anticancer efficacy of these compounds in breast cancer remain largely unexplored. Previous research shows that CBP/p300 serve as co-activators for ERα and are responsible for catalyzing Histone 3, lysine 18 and 27 acetylation (H3K18ac and H3K27ac) at ERα target genes. We hypothesize that CBP/p300 are critical for ERα function in driving oncogene expression and their pharmacologic inhibition will block ERα-mediated gene expression underpinning the tumor growth of luminal breast cancer. In support of our hypothesis, we report that small molecule inhibitors of the CBP/p300 HAT domain and bromodomain strongly inhibit estrogen- induced MYC expression and prevent colony formation in vitro of a panel of ER+ cell lines. Furthermore, inhibition of CBP/p300 also downregulates ERα activity in a luciferase assay using a construct driven by the conical ERα-binding DNA sequence. H3K27ac ChIP-seq data in the ER+ luminal breast cancer MCF-7 cells indicate that pharmacologic inhibition of CBP/p300 catalytic function blocks specific enhancer function. Our study suggests pharmacologically targeting CBP/p300 may be an effective strategy for treating luminal breast cancer. (Supported by James and Esther King Biomedical Research Program, and Bankhead-Coley Cancer Research Program, Florida Department of Health)

Citation Format: Aaron Richard Waddell, Iqbal Mahmud, Zhiguang Huo, Daiqing Liao. Pharmacologic inhibition of CBP/p300 suppresses estrogen-induced gene expression and proliferation in ER+ luminal breast cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4669.

Assays for Validating Histone Acetyltransferase Inhibitors

Lysine acetyltransferases (KATs) catalyze acetylation of lysine residues on histones and other proteins to regulate chromatin dynamics and gene expression. KATs, such as CBP/p300, are under intense investigation as therapeutic targets due to their critical role in tumorigenesis of diverse cancers. The development of novel small molecule inhibitors targeting the histone acetyltransferase (HAT) function of KATs is challenging and requires robust assays that can validate the specificity and potency of potential inhibitors. This article outlines a pipeline of three methods that provide rigorous in vitro validation for novel HAT inhibitors (HATi). These methods include a test tube HAT assay, Chromatin Hyperacetylation Inhibition (ChHAI) assay, and Chromatin Immunoprecipitation-quantitative PCR (ChIP-qPCR). In the HAT assay, recombinant HATs are incubated with histones in a test tube reaction, allowing for acetylation of specific lysine residues on the histone tails. This reaction can be blocked by a HATi and the relative levels of site-specific histone acetylation can be measured via immunoblotting. Inhibitors identified in the HAT assay need to be confirmed in the cellular environment. The ChHAI assay uses immunoblotting to screen for novel HATi that attenuate the robust hyperacetylation of histones induced by a histone deacetylase inhibitor (HDACi). The addition of an HDACi is helpful because basal levels of histone acetylation can be difficult to detect via immunoblotting. The HAT and ChHAI assays measure global changes in histone acetylation, but do not provide information regarding acetylation at specific genomic regions. Therefore, ChIP-qPCR is used to investigate the effects of HATi on histone acetylation levels at gene regulatory elements. This is accomplished through selective immunoprecipitation of histone-DNA complexes and analysis of the purified DNA through qPCR. Together, these three assays allow for the careful validation of the specificity, potency, and mechanism of action of novel HATi.

0919 Health Disparities in the Persistence of Childhood Insomnia Symptoms in the Transition to Adolescence: The Penn State Child Cohort

Introduction

A strong body of cross-sectional evidence indicates that social determinants of health (SDH), such as race, ethnicity, socioeconomic status, and sex/gender, are linked to sleep problems, including insomnia symptoms. Few studies have examined the longitudinal association between SDH and the persistence and remission of insomnia symptoms in the transition between childhood and adolescence, a critical period for sleep health.

Methods

The Penn State Child Cohort is a random, population-based sample of 700 children (5-12y at baseline), of whom 421 were followed up as adolescents (12-23y at follow-up). All subjects underwent polysomnography, clinical history, physical exam, and parent- and self-reported scales at baseline and follow-up. Childhood insomnia symptoms were defined as a parent- and/or self-report of difficulty falling and/or staying asleep. All subjects or their parents identified the subject’s sex, race, and ethnicity, and reported on socioeconomic status (SES) of the household.

Results

Females (32.7%) and racial/ethnic minorities (25.0%) were associated with a significantly lower remission rate as compared to males (53.3%) and non-Hispanic whites (48.3%), respectively. Non-Hispanic whites of low SES were associated with a significantly lower full remission rate (26.3%) as compared to non-Hispanic whites of higher SES (42.0%), while racial/ethnic minorities were associated with the lowest full remission rates regardless of whether they were of low (9.1%) or higher (11.1%) SES.

Conclusion

Our novel data indicate that gender-, racial/ethnic- and socioeconomic-related disparities in insomnia not only occur as early as childhood but are important determinants of insomnia’s chronic course throughout development.

Support

National Institutes of Health (R01HL136587, R01HL97165, R01HL63772, UL1TR000127)

0936 Cardiometabolic Disorders are Independently Associated with Excessive Daytime Sleepiness in Young Adults

Introduction

Cardiometabolic risk factors (CMR), including obesity, hypertension, diabetes and hypercholesterolemia, have been associated with sleep apnea and insufficient sleep, both of which can lead to excessive daytime sleepiness (EDS). We hypothesized that CMR are associated with EDS in young adults independent of sleep apnea, sleep duration and mental health disorders (MHD).

Methods

The Penn State Child Cohort is a population-based longitudinal sample of 700 children (8.7±1.7y), of whom 421 were followed-up 8.3 years later during adolescence (17.0±2.3y) and 425 another 7.0 years later during young adulthood (24.4±2.6y). Subjects underwent a 9-h in-lab polysomnography in childhood and adolescence and parent- or self-reported standardized surveys at all time points. Self-reports in young adulthood and in-lab measurements in childhood were used to ascertain CMR and sleep apnea. Parent-reports in childhood and self-reports in young adulthood were used to ascertain the presence of MHD and EDS. Logistic regression models adjusted for age, race, sex, snoring/observed apneas, insomnia symptoms, and sleep duration in young adulthood as well as mean arterial blood pressure, body mass index percentile and apnea/hypopnea index in childhood.

Results

CMR (OR=2.71, 95%CI=1.69-4.36) and MHD (OR=4.61, 95%CI=2.79-7.62) were associated with EDS in univariate models. After adjusting for covariates in childhood and young adulthood, CMR and MHD remained independently associated with EDS (OR=2.32, 95%CI=1.29-4.16 and OR=2.78, 95%CI=1.59-4.87, respectively).

Conclusion

EDS in young adults with CMR or MHD does not solely arise from sleep apnea, insufficient sleep or other sleep disturbances. EDS may be the result of central pathophysiologic mechanisms or the functional impairment associated with cardiovascular, metabolic and mental health disorders. These data further support that youth with these disorders should be screened for EDS and appropriately managed.

Support

National Institutes of Health (R01HL136587, R01HL97165, R01HL63772, UL1TR000127)

0920 Behavioral Profiles Associated with the Development of Insomnia Symptoms in Children with Known Mental Health Disorders

Introduction

Mental health disorders (MHD) are a known risk factor for the development of insomnia symptoms in youth. However, a number of children with MHD do not go on to develop insomnia symptoms later on in life. Little is known about possible childhood factors that exacerbate or mitigate the risk of developing adolescent insomnia symptoms (AIS) among children with MHD. The present study examined, in an at-risk group of children with MHD, the behavioral profiles associated with the development of AIS.

Methods

The Penn State Child Cohort is a random, population-based sample of 700 children (5-12y), of whom 421 were followed up as adolescents (12-23y). Absence of childhood insomnia symptoms was ascertained by parent-reports (n=312), while presence of AIS in this subgroup was ascertained by self-reports (n=97). Presence of MHD was ascertained based on the clinical history and physical exam at baseline (n=52). The Pediatric Behavior Scale (PBS) assessed multiple parent-reported behavioral domains.

Results

Children with MHD at baseline had greater levels of difficulty across a variety of internalizing (e.g., anxiety, depression) and externalizing (e.g., impulsivity, hyperactivity) behavioral domains than those without MHD, regardless of whether they developed AIS. However, children with MHD who went on to develop AIS had significantly greater levels of aggressive (p&lt;0.001) and oppositional (p=0.006) behaviors relative to children with MHD who did not develop AIS. In fact, these latter children did not differ from peers without any history of MHD or AIS on levels of aggressive (p=0.820) or oppositional (p=0.436) behaviors.

Conclusion

Children with MHD who present with normative aggressive and oppositional behaviors are less likely to develop AIS. Healthcare providers should consider providing preventative sleep interventions to youth with MHD who are exhibiting comorbid externalizing behaviors.

Support

National Institutes of Health (R01HL136587, R01HL97165, R01HL63772, UL1TR000127)

0319 Sleep Architecture and Neurocognitive and Behavioral Functioning in Youth from the General Population

Introduction

The transition from childhood to adolescence is critical for the onset of psychopathology and reflects significant changes in the sleeping brain. Sleep deprivation studies have shown that rapid eye movement (REM) and non-rapid eye movement (NREM) sleep are differentially involved in specific cognitive functions. The aim of this study was to examine the association of sleep architecture with neurobehavioral outcomes in a population-based sample.

Methods

We studied 700 children (5-12y, 47.1% female, 23.7% minority) and 421 adolescents (12-23y, 46.1% female, 21.8% minority) from the Penn State Child Cohort. All subjects underwent a 9-hour polysomnography and a 4-hour neurobehavioral evaluation. Neurocognitive outcomes included the Stroop test, digit span backwards (DSB), and coding to measure high- and low-order cognitive functions. Behavioral outcomes included the Child/Adult Behavior Checklist to measure internalizing symptoms and externalizing behaviors. Correlation analysis examined the cross-sectional association between sleep architecture and neurocognitive and behavioral outcomes.

Results

In childhood, %REM sleep was negatively associated with DSB scores (r=-0.088, p=0.027), particularly in males (r=-0.167, p=0.002). Furthermore, %NREM sleep was positively associated with DSB scores in males (r=0.126, p=0.021). In adolescent females, %NREM and %REM sleep were positively (r=0.146, p=0.044) and negatively (r=-0.158, p=0.029) associated with DSB scores, respectively. In adolescence, %NREM sleep was negatively associated with internalizing symptoms (r=-0.109, p=0.026).

Conclusion

Male children and female adolescents who spent a higher proportion of the night in NREM sleep had better working memory performance. Adolescent females who spent a lower proportion of the night in NREM sleep had greater internalizing symptoms. This study suggests a role for sleep architecture in neurobehavioral deficits in youth. Future studies are necessary to determine the contributions of low- and high-frequency sleep EEG dynamics to these clinical outcomes.

Support

National Institutes of Health (R01MH118308, R01HL97165, R01HL63772, UL1TR000127)

0457 Insomnia and Cause-Specific Mortality in Men and Women

Introduction

The association of insomnia with an increased risk of mortality has remained inconsistent across studies, which contrasts with accumulating evidence linking this prevalent and chronic sleep disorder with cardiovascular, cerebrovascular, oncologic, and psychiatric morbidity. The higher prevalence of insomnia in women compared to men may be an important contributor to the different survival rates reported in large, population-based studies.

Methods

The Penn State Adult Cohort is a random, general population sample of 1,741 adults (48.8±13.6y, 52.2% women) who were studied in the sleep laboratory and followed-up for their cause of death up to December 31, 2018. Insomnia was defined as a chronic complaint lasting at least 1 year (n=199). We assessed the risk of all-cause mortality (n=664) and the two most common causes of death: cardiovascular/cerebrovascular (n=275) and cancer (n=161). Cox proportional hazard models adjusted for age, race, sex, education, smoking, alcohol, BMI, AHI, cognitive impairment, mental health problems and physical health problems, including hypertension, diabetes, heart disease, stroke and cancer at baseline.

Results

The risk of all-cause mortality associated with insomnia was significantly increased in men (HR=1.84, 95%CI=1.18-2.87) but not in women (HR=0.80, 95%CI=0.57-1.13; p for sex-interaction&lt;0.01). Insomnia was significantly associated with an increased risk of cardiovascular/cerebrovascular mortality in men (HR=2.11, 95%CI=1.14-3.99), but not in women (HR=0.98, 95%CI=0.59-1.63; p for sex-interaction=0.06). Insomnia was not significantly associated with an increased risk of cancer mortality either in men (HR=1.41, 95% CI=0.56-3.56) or in women (HR=0.90, 95% CI=0.45-1.80), after adjusting for hypertension, diabetes, heart disease, stroke and cancer at baseline.

Conclusion

Men with chronic insomnia are at an increased risk of mortality, particularly that of cardiovascular/cerebrovascular origin. There is a need for translational studies focused on sex-differences that can disentangle the biological and behavioral mechanisms underlying women’s resilience.

Support

American Heart Association (14SDG19830018), National Institutes of Health (R01HL51931, R01HL40916)

0878 Association of Obstructive Sleep Apnea with Internalizing Symptoms vs. Externalizing Behaviors in Adolescents with Attention Deficit Hyperactivity Disorder

Introduction

Attention deficit hyperactivity disorder (ADHD) in children has been associated with insomnia, obstructive sleep apnea (OSA), and abnormal periodic limb movements (PLMS). However, there is lack of data examining the contribution of OSA to ADHD-related internalizing symptoms and externalizing behaviors in adolescents.

Methods

We studied the Penn State Child Cohort, a random general population sample of 700 children (8.7±1.7y), of whom 421 were followed-up 8.3 years later during adolescence (17.0±2.3y, 53.9% male). All adolescents underwent a 9-hour PSG, clinical history and physical examination. ADHD was ascertained by a parent- or self-report of having been diagnosed with ADHD. OSA was defined as an apnea hypopnea index (AHI) of ≥2 events per hour of sleep, while a periodic limb movement index (PLMI) ≥5 events per hour of sleep was indicative of PLMS. Controls, OSA-alone, ADHD-alone and ADHD+OSA were identified. The Child or Adult Behavior Checklist were used to ascertain internalizing and externalizing behaviors. Multivariable-adjusted models controlled for sex, race, age, and body mass index (BMI) percentile.

Results

As compared to controls, adolescents with ADHD-alone or ADHD+OSA had significantly greater externalizing behaviors (p&lt;0.001), inattention (p&lt;0.001) and thought problems (p&lt;0.001). While adolescents with ADHD-alone had higher internalizing symptoms (p=0.021), specifically withdrawn-depression (p&lt;0.01), adolescents with ADHD+OSA had more somatic problems than controls (p=0.048). There were no statistically significant differences in behavioral outcomes between controls and adolescents with OSA-alone or between adolescents with ADHD-alone and ADHD+OSA.

Conclusion

Adolescents with comorbid ADHD and OSA do not present with worse behavioral outcomes than those with ADHD alone. Future studies should examine whether the progression of these adolescents into young adulthood differs in terms of their behavioral outcomes and development of mental health disorders.

Support

National Institutes of Health (R01HL136587, R01HL97165, R01HL63772, UL1TR000127)

0890 Sleep Disordered Breathing is Associated With Endothelial Dysfunction and Atherosclerosis in Young Adults: Preliminary Longitudinal Findings in the Penn State Child Cohort

Introduction

Sleep disordered breathing (SDB) in middle-age is an established risk factor for cardiovascular disease. However, population-based studies supporting its cardiovascular contribution at earlier stages of development are lacking, particularly with long-term follow-ups.

Methods

The Penn State Child Cohort is a population-based longitudinal sample of 700 children (8.7±1.7y), of whom 421 were followed-up 8.3 years later during adolescence (17.0±2.3y) with in-lab polysomnography (PSG). To date, 425 have been followed-up another 7.4 years later during young adulthood (24.4±2.6y) via a standardized survey and 136 of them (55.1% female, 21.3% racial/ethnic minority) have undergone a repeat of their PSG to ascertain apnea/hypopnea index. Subjects (n=121) also underwent Doppler ultrasounds to assess flow-mediated dilation (FMD) and carotid intima-media thickness (CIMT). Linear regression models stratified by body mass index in young adulthood.

Results

SDB was cross-sectionally associated with lower FMD (β=-0.239, p=0.008) and greater CIMT (β=0.330, p&lt;0.001) in young adulthood. Longitudinally, childhood (n=121) and adolescence (n=90) SDB were significantly associated with CIMT (β=0.327, p&lt;0.001 and β=0.286, p=0.006, respectively), but not with FMD (β=-0.158, p=0.08 and β=-0.101, p=0.35, respectively). These associations, particularly longitudinal ones between childhood and adolescence SDB with CIMT in young adulthood, were stronger in overweight than normal weight subjects (e.g., β=0.310, p=0.030 and β =0.089, p=0.582, respectively).

Conclusion

SDB and obesity appear to be synergistically associated with endothelial dysfunction and atherosclerosis in young adults from the general population. These data suggest that a childhood exposure to chronic SDB is associated with long-term atherosclerosis, while endothelial dysfunction may be a short-term outcome. This ongoing 16-year longitudinal study will test whether the natural history of SDB from childhood through adolescence into young adulthood shows differential trajectories for cardiovascular morbidity.

Support

National Institutes of Health (R01HL136587, R01HL97165, R01HL63772, UL1TR000127)

DAXX in cancer: phenomena, processes, mechanisms and regulation

DAXX displays complex biological functions. Remarkably, DAXX overexpression is a common feature in diverse cancers, which correlates with tumorigenesis, disease progression and treatment resistance. Structurally, DAXX is modular with an N-terminal helical bundle, a docking site for many DAXX interactors (e.g. p53 and ATRX). DAXX's central region folds with the H3.3/H4 dimer, providing a H3.3-specific chaperoning function. DAXX has two functionally critical SUMO-interacting motifs. These modules are connected by disordered regions. DAXX's structural features provide a framework for deciphering how DAXX mechanistically imparts its functions and how its activity is regulated. DAXX modulates transcription through binding to transcription factors, epigenetic modifiers, and chromatin remodelers. DAXX's localization in the PML nuclear bodies also plays roles in transcriptional regulation. DAXX-regulated genes are likely important effectors of its biological functions. Deposition of H3.3 and its interactions with epigenetic modifiers are likely key events for DAXX to regulate transcription, DNA repair, and viral infection. Interactions between DAXX and its partners directly impact apoptosis and cell signaling. DAXX's activity is regulated by posttranslational modifications and ubiquitin-dependent degradation. Notably, the tumor suppressor SPOP promotes DAXX degradation in phase-separated droplets. We summarize here our current understanding of DAXX's complex functions with a focus on how it promotes oncogenesis.

Shock-Induced Damage and Dynamic Fracture in Cylindrical Bodies Submerged in Liquid

Understanding the response of solid materials to shock loading is important for mitigating shock-induced damages and failures, as well as advancing the beneficial use of shock waves for material modifications. In this paper, we consider a representative brittle material, BegoStone, in the form of cylindrical bodies and submerged in water. We present a computational study on the causal relationship between the prescribed shock load and the resulting elastic waves and damage in the solid material. A recently developed three-dimensional computational framework, FIVER, is employed, which couples a finite volume compressible fluid solver with a finite element structural dynamics solver through the construction and solution of local, one-dimensional fluid-solid Riemann problems. The material damage and fracture are modeled and simulated using a continuum damage mechanics model and an element erosion method. The computational model is validated in the context of shock wave lithotripsy and the results are compared with experimental data. We first show that after calibrating the growth rate of microscopic damage and the threshold for macroscopic fracture, the computational framework is capable of capturing the location and shape of the shock-induced fracture observed in a laboratory experiment. Next, we introduce a new phenomenological model of shock waveform, and present a numerical parametric study on the effects of a single shock load, in which the shock waveform, magnitude, and the size of the target material are varied. In particular, we vary the waveform gradually from one that features non-monotonic decay with a tensile phase to one that exhibits monotonic decay without a tensile phase. The result suggests that when the length of the shock pulse is comparable to that of the target material, the former waveform may induce much more significant damage than the latter one, even if the two share the same magnitude, duration, and acoustic energy.

Abstract 5214: Targeting the estrogen receptor pathway in luminal breast cancer through inhibition of p300/CBP

Luminal breast cancer represents approximately two thirds of all breast cancer cases and is characterized by the expression of hormone receptors, such as the estrogen receptor alpha (ER). ERα is a member of the steroid nuclear receptor family and is involved in a hormonal signaling pathway that drives tumor growth through upregulation of genes involved in cell cycle progression, such as MYC and CCND1. Antagonists of ER function are the standard of care treatment for ER+ luminal breast cancer. However, resistance to ER antagonists is common in advanced breast cancer cases. Therefore, there is an urgent need to investigate new therapeutics that can be utilized to treat tumors that are resistant to traditional therapies. p300/CBP are two paralogous acetyltransferases that catalyze histone 3, lysine 18 and 27 acetylation (H3K18ac and H3K27ac) at promoters and enhancers to promote gene expression. ER mediated transcription is critically reliant upon the recruitment of co-activators, including p300/CBP. However, the mechanistic role of p300/CBP catalytic activity in globally regulating ER mediated transcription remains poorly understood. Inhibition of p300/CBP, as a critical co-activator of ER, potentially represents an applicable strategy for inhibiting ER function in luminal breast tumors. Importantly, the catalytic histone acetyltransferase (HAT) domain of p300/CBP is under intense investigation as a target of small molecule therapeutics in cancer. We analyzed publicly available data and report that p300/CBP are upregulated at the mRNA level in breast cancer, including the luminal subtypes, and that their expression negatively correlates with patient survival. We also found that pharmacologic inhibition of p300/CBP HAT activity in ER+ cell lines potently suppresses ER mediated transcription, downregulates ER, c-Myc and Cyclin D1 protein levels and prevents estrogen induced growth in vitro. Studies are underway to understand how p300/CBP regulates ER signaling using genetic, pharmacologic, and biochemical methods to assess the therapeutic effects of pharmacologic p300/CBP inhibition on ER+ breast cancer. (Supported by Bankhead-Coley Research Program, and James and Esther King Biomedical Research Program, Florida Department of Health)

Citation Format: Aaron Waddell, Iqbal Mahmud, Guimei Tian, Daiqing Liao. Targeting the estrogen receptor pathway in luminal breast cancer through inhibition of p300/CBP [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5214.

Abstract 4718: SR-4370, a potent and selective inhibitor of class I HDACs, suppresses AR signaling and in vivo prostate tumor growth

Androgen receptor (AR) is an androgen-activated transcription factor and drives prostate cancer (PCa) progression. Class I HDACs 1-3 are critical for activating AR-mediated transcription. Thus, targeting these HDACs is a promising strategy for treating PCa. Notably, along with significant adverse effects, several FDA-approved HDAC inhibitors broadly inhibiting different HDACs were ineffective for treating castration-resistant prostate cancer in clinical trials. Significantly, entinostat, an aminobenzamide analog specific to HDACs 1-3, extended overall survival for patients with breast cancer resistant to endocrine therapy. These observations suggest that HDACi selective to HDACs 1-3 may be effective for treating solid tumors including PCa. We have recently discovered the novel benzoylhydrazide class of HDAC inhibitors highly specific to HDACs 1-3. An optimized analog, SR-4370, exhibited low µM to nM potency against HDACs 1-3. SR-4370 markedly suppressed AR signaling, PCa cell proliferation in vitro, and prostate tumor growth in vivo. Gene expression profiling experiments revealed that SR-4370 downregulated AR, AR-Vs and AR target genes as well as the MYC oncogenic network. Chromatin accessibility assay using ATAC-seq showed that SR-4370 altered chromatin states in PCa cells. The chromatins with AR-binding sites became inaccessible on SR-4730 treatment, indicating that altered chromatin accessibility may contribute to the inhibition of AR signaling. Interestingly, SR-4370 sensitized C4-2 cells to enzalutamide. In PCa xenograft models, SR-4370 was effective to suppress tumor growth in vivo. Importantly, SR-4370 was well tolerated and did not cause observable adverse effects as judged by body weight and blood chemistry tests of treated mice. Our data suggest that SR-4370 may be a safe and clinically applicable treatment for advanced PCa refractory to current frontline treatments. (Supported by UFHealth Cancer Center, Florida Breast Cancer Foundation, James and Esther King Biomedical Research Program, and Bankhead-Coley Cancer Research Program, Florida Department of Health)

Citation Format: Iqbal Mahmud, Guimei Tian, Jia Wang, Ryan Stowe, Zhiguang Huo, Yushan Zhang, Hamsa Thayek Purayil, Eric Helm, Theodore Drashansky, Dorina Avram, Yehia Daaka, William R. Roush, Daiqing Liao. SR-4370, a potent and selective inhibitor of class I HDACs, suppresses AR signaling and in vivo prostate tumor growth [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4718.

Abstract 2612: Roles of USF1 in breast tumorigenesis and disease progression

Breast cancer accounts for nearly one-quarter of all cancer diagnoses and is the principal cause of cancer-related mortality in women worldwide. Triple negative breast cancer (TNBC) is a clinically aggressive subtype of breast cancer commonly resistant to therapeutics that have been successful in increasing survival in patients with ER+, PR+ and HER2+ breast cancer subtypes. As such, identifying factors that contribute to poor patient outcomes and mediate the growth and survival of TNBC cells remain important areas of investigation. USF1 (upstream stimulatory factor 1), a gene linked to drive lipogenesis and cellular proliferation, is overexpressed in human malignancies, yet its contribution to cancer remains unclear. In analyzing large number of genomic datasets including The Cancer Genome Atlas (TCGA), we found that USF1 expression is significantly higher in TNBC patient samples. Also, USF1 gene expression positively correlates with key lipogenic enzymes. Significantly, we found that high expression of USF1 in breast cancer correlates with decreased patient survival. We therefore hypothesize that USF1 promotes breast tumorigenesis and progression by activating lipogenic gene expression. We conducted pilot in vitro studies to determine the influence of USF1 expression and cell proliferation. It was demonstrated that knockdown of USF1 decreased cellular proliferation in 2D cell culture of the TNBC cell line MDA-MB-231. We also assessed the effects on USF1 expression levels on in vivo tumor growth. We found that USF1 overexpression and knockdown enhanced and reduced tumor growth in vivo, respectively. Further studies are underway to determine the mechanisms by which USF1 promotes TNBC tumorigenesis and metastatic progression. Our studies will shed lights on roles of USF1 in breast cancer tumor biology. (Supported by McKnight Foundation, Bankhead-Coley Cancer Research Program and James and Esther King Biomedical Research Program, Florida Department of Health.)

Citation Format: Jessica Lewis, Iqbal Mahmud, Guimei Tian, Daiqing Liao. Roles of USF1 in breast tumorigenesis and disease progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2612.

The biomechanical properties of the urethra in boys with hypospadias: a preliminary study

PURPOSE

The ventral aspect of the penis in boys with hypospadias is composed of dysplastic tissue of the skin and the urethra. The aim of this study was to assess the pre-operative size and biomechanical properties of urethrae in boys with and without hypospadias using a more objective catheter-based system.

MATERIALS & METHODS

In this non-blinded clinical observation study, the study population consisted of 19 boys with hypospadias-the case group (median age 13.9 months [range: 12.2-21.3])-and seven boys without hypospadias-the control group (median age 8.5 months [range: 3.8-18.1]). Modified measurements of impedance were used to assess the size, compliance and viscoelasticity of the urethrae under stepwise increased pressures (between 0, 40 and 60 cmH₂O) using a customised Endolumenal Functional Lumen Imaging probe (EndoFLIP®).

RESULTS

The sizes of the urethrae in boys with hypospadias are variable but tend towards being narrower and less compliant than those of the control subjects i.e. median diameter for meatus urethra was 3.2 mm (range: 2.98-3.92) in the hypospadias group compared with 3.64 (range: 3.22-4.44) in the control group at 40 cmH₂O, and the median change in diameter at meatus urethra was 0.08 mm (range: -0.02 to 0.52) in the hypospadias group compared with 0.23 mm (range: -0.02 to 0.34) when the pressure was increased from 40 to 60 cmH₂O. This biomechanical analysis found that there was no significant viscoelasticity of the urethral meatus in both the groups, whereas the remainder of the urethral structure generally had viscoelastic properties in the control group, seen as a creep on the time/diameter curves (Figure). In the group of boys with hypospadias, evaluations of the urethrae revealed varying viscoelastic abilities, ranging from abilities that were comparable with those of the control subjects to no sign of viscoelasticity at all.

CONCLUSIONS

This study is the first to measure the biomechanical properties of the urethra in children, which might help to provide an understanding as to the structural and functional changes associated with hypospadias. The urethrae in the subjects with hypospadias were variable in diameter but tended to be narrower overall, especially in the distal portion of the urethra. Furthermore, the urethrae in boys with hypospadias were frequently less viscoelastic than those of controls.

CLINICAL RELEVANCE

The EndoFLIP® system may be a future way of objectively estimating the severity of a urethral obstruction and could potentially be included in the postoperative assessment of patients with signs of hampered voiding.

Predictors of Early and Late Mortality in Older Kidney Transplant Recipients

BACKGROUND

Older kidney patients with chronic kidney disease benefit significantly from kidney transplantation. However, these older transplant recipients have greater mortality after transplantation than younger transplant recipients. Understanding the impact of comorbidities on post-transplant mortality can improve risk stratification and patient selection.

METHODS

A single-center analysis of 3105 kidney transplant recipients was performed over a 12-year period. Comorbidities associated with death were evaluated in older and younger transplant recipients.

RESULTS

The 2 most important factors associated with increased mortality in the first 100 days after transplant were recipient age ≥60 and receipt of deceased donor organs (adjusted odds ratios, 3.29 and 5.80, respectively), with no statistically significant impact of recipient comorbidities. In the later post-transplant period (after the first 100 days), recipient age ≥60 and receipt of deceased donor organs (adjusted hazard ratios [HR] of 2.14 and 2.29, respectively) remained predictors of mortality. We also found that donor age ≥60 and the recipient having cardiovascular disease and diabetes were independent predictors of increased mortality. There was a statistically significant interaction between diabetes and heart disease and recipient age ≥60, with a lesser impact on late mortality in older patients compared to younger patients.

CONCLUSIONS

This analysis suggests that comorbidities have a larger impact later after transplantation, with less effect on older recipients. These observations suggest that certain comorbid conditions should be evaluated differently in older patients compared to younger ones.

Childhood obesity, weight loss and developmental trajectories predict the persistence and remission of childhood sleep-disordered breathing

BACKGROUND

Obesity has been recognized as a risk factor for childhood sleep-disordered breathing (SDB), yet it remains unclear how obesity and weight change predict the course of childhood SDB.

OBJECTIVE

The objective of the study is to investigate the role of body weight, upper airway abnormalities and developmental trajectories on the persistence and remission of childhood SDB in the transition to adolescence.

METHODS

The Penn State Child Cohort is a representative population sample of 700 children (5-12 years), of whom 421 were followed up as adolescents (12-23 years). Participants underwent a clinical history, physical examination and polysomnography at both time points.

RESULTS

Obesity and enlarged tonsils were cross-sectionally associated with childhood SDB. Longitudinally, baseline obesity predicted the persistence of childhood SDB (OR = 3.75, 95% CI = 2.00-7.05), while weight loss predicted its remission (OR = 1.67, 95% CI = 1.11-2.50). Children with enlarged tonsils who remitted from SDB had not experienced significant weight loss and only 4.4% had undergone adeno/tonsillectomy. Body fat distribution/composition at follow-up was similar in those who had remitted from childhood SDB as compared with those who had never experienced SDB, while those who persisted with childhood SDB showed significant android distribution and visceral adiposity at follow-up.

CONCLUSIONS

Our data support a causal role for obesity and weight loss in the chronicity and remission, respectively, of childhood SDB in the transition to adolescence and suggest that remission of SDB is related to developmental trajectories of the upper airway in a significant proportion of children. Thus, targeting childhood obesity and weight gain should be a priority in the prevention and treatment of SDB during this critical developmental period.

Association of PON1 gene polymorphisms with polycystic ovarian syndrome risk: a meta-analysis of case-control studies

PURPOSE

Evidences showed that paraoxonase 1 (PON1) gene polymorphism has an impact on women's susceptibility to polycystic ovarian syndrome (PCOS) by influencing the expression and activity of PON1. However, the effects of three PON1 polymorphisms (- 108 C>T, L55M and Q192R) on the incidence of PCOS have generated inconsistent results. Here, we conducted a meta-analysis to investigate the association between PON1 polymorphisms and PCOS risk.

METHODS

All eligible trials were identified via systematic searches of multiple literature databases. Outcome data were synthesized by using crude odds ratio with 95% confidence interval. Heterogeneity was assessed with the I² test. Publication bias and subgroup analyses were also performed.

RESULTS

A total of 2449 cases and 1977 controls from nine studies were selected for analysis. The pooled results showed a significant association between PCOS risk and PON1 - 108 C/T polymorphism in the following genetic models [allelic, 0.72 (0.56-0.92); homozygote, 0.51 (0.32-0.82); heterozygote, 0.44 (0.25-0.78); and dominant 0.47 (0.29-0.77)]. For the PON1 192 Q/R polymorphism, a significant relationship was found in the allelic model [0.62 (0.41-0.93)] and recessive model [0.61 (0.37-0.98)]. PCOS risk was also linked to PON1 L55M polymorphism in the heterozygote model [0.62 (0.39-0.98)] and dominant model [0.63 (0.41-0.96)].

CONCLUSIONS

Our study has shown that PON1 - 108 C/T polymorphism might be associated with increased risk of PCOS under the allelic, homozygote, heterozygote, and dominant models. Additionally, PON1 192 Q/R and L55M polymorphisms were significantly related only in the allelic and recessive model, and in the heterozygote and dominant model, respectively.

Inhibition of androgen receptor transactivation function by adenovirus type 12 E1A undermines prostate cancer cell survival

BACKGROUND

Mutations or truncation of the ligand-binding domain (LBD) of androgen receptor (AR) underlie treatment resistance for prostate cancer (PCa). Thus, targeting the AR N-terminal domain (NTD) could overcome such resistance.

METHODS

Luciferase reporter assays after transient transfection of various DNA constructs were used to assess effects of E1A proteins on AR-mediated transcription. Immunofluorescence microscopy and subcellular fractionation were applied to assess intracellular protein localization. Immunoprecipitation and mammalian two-hybrid assays were used to detect protein-protein interactions. qRT-PCR was employed to determine RNA levels. Western blotting was used to detect protein expression in cells. Effects of adenoviruses on prostate cancer cell survival were evaluated with CellTiter-Glo assays.

RESULTS

Adenovirus 12 E1A (E1A12) binds specifically to the AR. Interestingly, the full-length E1A12 (266 aa) preferentially binds to full-length AR, while the small E1A12 variant (235 aa) interacts more strongly with AR-V7. E1A12 promotes AR nuclear translocation, likely through mediating intramolecular AR NTD-LBD interactions. In the nucleus, AR and E1A12 co-expression in AR-null PCa cells results in E1A12 redistribution from nuclear foci containing CBX4 (also known as Pc2), suggesting a preferential AR-E1A12 interaction over other E1A12 interactors. E1A12 represses AR-mediated transcription in reporter gene assays and endogenous AR target genes such as ATAD2 and MYC in AR-expressing PCa cells. AR-expressing PCa cells are more sensitive to death induced by a recombinant adenovirus expressing E1A12 (Ad-E1A12) than AR-deficient PCa cells, which could be attributed to the increased viral replication promoted by androgen stimulation. Targeting the AR by E1A12 promotes apoptosis in PCa cells that express the full-length AR or C-terminally truncated AR variants. Importantly, inhibition of mTOR signaling that blocks the expression of anti-apoptotic proteins markedly augments Ad-E1A12-induced apoptosis of AR-expressing cells. Mechanistically, Ad-E1A12 infection triggers apoptotic response while activating the PI3K-AKT-mTOR signaling axis; thus, mTOR inhibition enhances apoptosis in AR-expressing PCa cells infected by Ad-E1A12.

CONCLUSION

Ad12 E1A inhibits AR-mediated transcription and suppresses PCa cell survival, suggesting that targeting the AR by E1A12 might have therapeutic potential for treating advanced PCa with heightened AR signaling.

Abstract B004: A combination of two chemically distinct inhibitors of class I HDACs is highly effective to suppress AR signaling and in vivo growth of prostate cancer xenograft

Class I HDACs 1-3 are critical for the AR-mediated transcriptional program. Thus, targeting class I HDACs is a promising strategy for treating prostate cancer. However, several FDA-approved HDAC inhibitors (HDACi) broadly inhibiting different HDACs have been shown to be ineffective and overtly toxic for treating castration-resistant prostate cancer in clinical trials. These observations suggest that HDACi selective for class I HDACs may be more effective but less toxic for treating prostate cancer than pan HDACi. Notably, we and others have shown that HDACi of different chemical classes individually exhibit nonoverlapping but limited effects on the acetylome in cancer cells. We hypothesize that a combination treatment strategy with class I HDAC-selective HDACi of different chemical classes is more effective to block AR signaling and prostate tumor growth than such HDACi individually. We have recently discovered the novel benzoylhydrazide chemo-type of class I HDAC-selective HDACi with a unique pharmacologic profile. Medicinal chemistry effort led to an optimized analog, SR-4370, with 6 nM potency to HDAC3. In support of our hypothesis, SR-4370 in combination with the clinical class I HDACi entinostat markedly suppressed AR signaling, prostate cancer cell proliferation in vitro, and tumor growth in vivo, and the tumor-suppressive effects by the HDACi combination were more pronounced than by SR-4370 and entinostat individually. Gene expression profiling experiments revealed that the SR-4370/entinostat combination profoundly downregulated AR, AR-V7, and AR target genes, while activating immune and cell death signaling pathways. In a C4-2 xenograft model using athymic nude mice, the SR-4370/entinostat combination was highly effective in suppressing tumor growth. Importantly, these HDACi alone or in combination did not cause observable adverse effects judged by body weight and blood chemistry tests of treated mice. Overall, our data suggest that the SR-4370/entinostat combination may be a translatable treatment for castration-resistant prostate cancer.

Citation Format: Guimei Tian, Iqbal Mahmud, Ryan Stowe, Yushan Zhang, Hamsa Thayek Purayil, William Roush, Yehia Daaka, Daiqing Liao. A combination of two chemically distinct inhibitors of class I HDACs is highly effective to suppress AR signaling and in vivo growth of prostate cancer xenograft [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr B004.

Abstract LB-248: Chemically distinct class I HDAC inhibitors synergize to inhibit global lipid metabolism in cancer

An increased rate of lipid production is a hallmark metabolic feature in cancer cells, which provides energy supplies, building blocks for membrane biogenesis, and signaling molecules for increased cancer cell proliferation. Current chemotherapeutic strategies targeting lipid metabolism have shown significant limitations, and as such, there is great interest in discovering novel therapies that effectively inhibit lipid production in cancer cells. Class I histone deacetylases (HDACs 1-3) are a key component of the epigenetic machinery regulating gene expression, and behave as oncogenes in several cancer types, spurring the development of HDAC inhibitors (HDACi) as novel anticancer drugs. Interestingly, HDAC inhibitors (HDACi) have been shown to decrease lipid production in different cells by modulating key genes in cholesterol synthesis, uptake, and efflux. However, effects of HDACi in lipid biosynthesis of cancer remains poorly studied. We have discovered a novel class of HDACi with a previously undescribed benzoylhydrazide scaffold. These new inhibitors are highly selective and potent to the class I HDACs (HDAC1, HDAC2, and HDAC3). Using global lipidomics approach by Ultra High-Performance Liquid Chromatography coupled High-Resolution Mass Spectrometry (UHPLC-HRMS), we found that a novel optimized analog, SR-4370, exhibits potent inhibition of lipid production in cells of diverse cancer types. Strikingly, SR-4370 in combination with entinostat, a benzamide analog of class I HDAC inhibitor currently in multiple clinical trials for treating breast cancer and other types of solid tumors, exhibits synergistic effects on inhibition of lipid production in cancer cells. We will present lipidomic profiling data from cells and xenograft tumors after treatment with SR-4370/entinostat, and discuss mechanisms of action for these distinct HDACi in inhibiting lipid production. In summary, our findings provide a rationale for inhibiting lipogenesis using isoform-selective HDACi in cancer therapy.

Citation Format: Iqbal Mahmud, Timothy J. Garrett, Ryan Stowe, William R. Roush, Daiqing Liao. Chemically distinct class I HDAC inhibitors synergize to inhibit global lipid metabolism in cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-248.

Abstract 1473: Role of acetyltransferases CBP and p300 in de novo fatty acid synthesis in colorectal cancer

CBP/p300 are two paralogous lysine acetyltransferases that acetylate protein substrates including histones, and serve as transcriptional co-activators for numerous signaling pathways involved in tumorigenesis and cancer progression. Recently, evidence has emerged that p300 regulates the transcription of genes involved in lipogenesis in cancers. Dysregulated lipogenesis and increased de novo production of fatty acids (FA) represent a major metabolic shift in cancer. De novo FA synthesis in cancer is suggested to be a source of lipids for membrane biogenesis, a reservoir of energy, and a source of pro-survival signaling molecules. Therefore, de novo FA synthesis has been linked to survival and increased proliferation of cancer cells, representing a potential area for therapeutic intervention. While emerging evidence indicates CBP/p300 may play a key role in regulating lipogenesis, little is known about the mechanism of how these proteins control lipid production in different cancers. Colorectal cancer (CRC) is a commonly diagnosed human cancer and is a major cause of cancer-related mortality. Key regulators for de novo FA synthesis, such as FASN, have been reported to be elevated in colorectal cancer. We analyzed publically available data sets and report that in colon adenocarcinoma, the mRNA levels of CBP/p300 positively correlate with the expression of genes involved in lipogenesis, such as FASN, SREBP1 and SREBP2. Furthermore, our analysis shows that EP300 expression is negatively correlated with patient survival. Strikingly, our preliminary data suggests that HDAC inhibitors may regulate p300 activity and could serve as a therapeutic approach for suppressing lipogenesis. We are currently utilizing small molecule inhibitors, genetic manipulation of the CREBBP/EP300 genes, and biochemical experiments to investigate the role of CBP/p300 in de novo FA synthesis in colorectal cancer. We hypothesize that inhibition of CBP/p300 could be an attractive therapeutic option for inhibiting tumor growth through downregulating de novo FA synthesis in colorectal cancer. (Supported by grants from James and Esther King Biomedical Research Program and Bankhead-Coly Cancer Research Program, Florida Department of Health.)

Citation Format: Aaron Waddell, Iqbal Mahmud, Daiqing Liao. Role of acetyltransferases CBP and p300 in de novo fatty acid synthesis in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1473.

Abstract 3953: The role of USF1 in the regulation of lipogenesis and breast cancer tumor progression

Breast cancer accounts for nearly one-quarter of all cancer diagnoses and is the principal cause of cancer-related mortality in women worldwide. Triple negative breast cancer (TNBC) is a clinically aggressive subtype of breast cancer commonly resistant to therapeutics that have been successful in increasing survival in patients with ER+, PR+ and HER2+ breast cancer subtypes. As such, identifying factors that contribute to poor patient outcomes and mediate the growth and survival of TNBC cells remain important areas of investigation. USF1 (upstream stimulatory factor 1), a gene linked to drive lipogenesis and cellular proliferation, is over-expressed in human malignancies, yet its contribution to cancer remains unclear. In analyzing large number of genomic datasets including The Cancer Genome Atlas (TCGA), we found that USF1 expression is significantly higher in TNBC tumor samples and cell lines. Also, USF1 gene expression positively correlates with key lipogenic enzymes. Significantly, we found that high expression of USF1 in breast cancer correlates with decreased patient survival. We found that USF1 shRNA expression resulted in cell death in breast cancer cell lines. We therefore hypothesize that USF1 drives de novo lipogenesis to promote breast tumorigenesis. Further studies are underway to determine the mechanisms by which USF1 promotes de novo lipogenesis, tumorigenesis and metastatic progression. Our studies will shed lights on the roles of USF1 in breast cancer tumor biology and undercover potential novel anticancer drug targets. (Supported by McKnight Foundation, Bankhead-Coley Cancer Research Program and James and Esther King Biomedical Research Program, Florida Department of Health.)

Citation Format: Jessica Lewis, Iqbal Mahmud, Daiqing Liao. The role of USF1 in the regulation of lipogenesis and breast cancer tumor progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3953.

Abstract LB-312: GRK5 activity mediates in vivo and in vitro prostate cancer progression and chemoresistance

Despite decades of research targeting the activity of the androgen receptor (AR), patients diagnosed with locally advanced and metastatic prostate cancer face an incurable disease. The Daaka lab investigates constituents of G-protein-coupled receptor signaling cascades for their ability to provide mitogenic signaling, which promotes PCa progression. We previously identified G protein-coupled receptor 5 (GRK5) for its ability to regulate PCa progression, independent of AR activity. GRK5 partially partitions to the nucleus, wherein it has been shown to regulate the transcriptome in non-PCa models. To globally elucidate the mechanistic impact of GRK5 on PCa progression, we are investigating the impact of GRK5 on the PCa transcriptome. We hypothesize that GRK5's regulation of the PCa transcriptome promotes tumor progression. To assay the effect of GRK5 on the PCa transcriptome, RNA sequencing was performed in two cell lines: PC3 Control (PC3 shGFP) and PC3 GRK5 Knockdown (PC3 shGRK5).  Ontologic analysis identified the epithelial–mesenchymal transition (EMT) as being affected when GRK5 is depleted. The epithelial–mesenchymal transition (EMT) is highly associated with promoting PCa progression and chemoresistance, thus we selected this pathway for further investigation. Confirmatory western blot analysis and quantitative PCR (qPCR) validated that depleting GRK5 suppresses the expression of the mesenchymal markers Vimentin and N-Cadherin. Similarly, overexpression of GRK5 increases the expression of these mesenchymal markers. Stable overexpression of GRK5 promotes cells to develop a spindle-like morphology, indicative of a mesenchymal state. GRK5 mediates this mesenchymal transition through increasing the expression of the EMT transcription factor, Twist1. Further analysis identifies that GRK5 activity promotes in vitro invasion. Cell lines overexpressing GRK5 demonstrate an increase in resistance to docetaxel, the mainstay chemotherapy for advanced PCa. Overexpression of GRK5 promotes lymphatic intravasation. Overexpression of mutated forms of GRK5 that are relegated to the nucleus are able recapitulated all aforesaid changes, arguing that the nuclear activity of GRK5 mediates this effect. Collectively, this data presents a novel mechanism promoting PCa progression, independent of AR activity.

Citation Format: Joseph B. Black, Hamsa Thayele Purayil, Iqbal Mahmud, Daiqing Liao, Yehia Daaka. GRK5 activity mediates in vivo and in vitro prostate cancer progression and chemoresistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-312.

Degradation of DAXX by adenovirus type 12 E1B-55K circumvents chemoresistance of ovarian cancer to cisplatin

Adenovirus E1B 55-kilodalton (E1B-55K) mediated DAXX degradation represents a potential mechanism by which E1B-55K sensitizes cancer cells to chemotherapy. Here we report the effects of E1B-55K-mediated DAXX degradation in chemoresistant ovarian cancer cells on response to chemotherapy. Cells with E1B-55K expression were more sensitive to cisplatin than cells without E1B-55K expression. In vivo C13* xenograft studies showed that the combination of cisplatin and E1B-55K was markedly more effective to slow tumor growth and to confer prolonged survival of tumor-bearing mice than either cisplatin or E1B-55K alone. Our studies show that DAXX plays an important role in cisplatin resistance in ovarian cancer, and strategies that promote DAXX degradation such as E1B-55K expression in combination with cisplatin can overcome drug resistance and improve responses to standard chemotherapy. These results also indicate that E1B-55K might be a novel agent for enhancing treatment responses for cisplatin-resistant ovarian cancer.

βArrestin2 Mediates Renal Cell Carcinoma Tumor Growth

Renal Cell Carcinoma (RCC) is one of the most lethal urological cancers worldwide. The disease does not present early clinical symptoms and is commonly diagnosed at an advanced stage. Limited molecular drivers have been identified for RCC, resulting in the lack of effective treatment for patients with progressive disease. Ubiquitous βArrestin2 (βArr2) is well established for its function in the desensitization and trafficking of G protein-coupled receptors. More recently, βArr2 has been implicated in the regulation of fundamental cellular functions, including proliferation and invasion. We used bioinformatic and genetic approaches to determine role of βArr2 in RCC tumor growth. Analysis of published human datasets shows that ARRB2 (gene encoding βArr2) expression is increased in RCC tumor compared to normal tissue and that high levels of ARRB2 correlate with worse patient survival. Experimentally, we show that knockout of ARRB2 decreases rate of RCC cell proliferation and migration in vitro and xenograft tumor growth in animals. Mechanistically, βArr2 regulates c-Src activity, Cyclin A expression and cell cycle progression that are involved in tumor growth. These results show that βArr2 is a critical regulator of RCC tumor growth and suggest its utility as a potential marker and drug target to treat advanced disease.

Sevoflurane activates hippocampal CA3 kainate receptors (Gluk2) to induce hyperactivity during induction and recovery in a mouse model

BACKGROUND

In addition to general anaesthetic effects, sevoflurane can also induce hyperactive behaviours during induction and recovery, which may contribute to neurotoxicity; however, the mechanism of such effects is unclear. Volatile anaesthetics including isoflurane have been found to activate the kainate (GluK2) receptor. We developed a novel mouse model and further explored the involvement of kainate (GluK2) receptors in sevoflurane-induced hyperactivity.

METHODS

Maximal speed, mean speed, total movement distance and resting percentage of C57BL/6 mice were quantitatively measured using behavioural tracking software before and after sevoflurane anaesthesia. Age dependence of this model was also analysed and sevoflurane-induced hyperactivity was evaluated after intracerebral injection of the GluK2 receptor blocker NS-102. Neurones from the hippocampal CA3 region were used to undertake in vitro electrophysiological measurement of kainate currents and miniature excitatory postsynaptic potential (mEPSP).

RESULTS

Sevoflurane induced significant hyperactivities in mice under sevoflurane 1% anaesthesia and during the recovery period, characterized as increased movement speed and total distance. The hyperactivity was significantly increased in young mice compared with adults (P<0.01) and pre-injection of NS-102 significantly prevented this sevoflurane-induced hyperactivity. In electrophysiological experiments, sevoflurane significantly increased the frequency of mEPSP at low concentrations and evoked kainate currents at high concentrations.

CONCLUSIONS

We developed a behavioural model in mice that enabled characterization of sevoflurane-induced hyperactivity. The kainate (GluK2) receptor antagonist attenuated these sevoflurane-induced hyperactivities in vivo, suggesting that kainate receptors might be the underlying therapeutic targets for sevoflurane-induced hyperactivities in general anaesthesia.

Esophagogastric junction in systemic sclerosis: A study with the functional lumen imaging probe

BACKGROUND

Fibrosis and atrophy of esophageal smooth muscle cells cause gastro-esophageal reflux and dysphagia in most patients with systemic sclerosis (SSc). Recent studies indicate that distensibility of the esophagogastric junction (EGJ), assessed with the Functional Lumen Imaging Probe (FLIP) may be a more sensitive and accurate measure of sphincter function than manometry. We aim to describe and compare distension parameters of the EGJ in a well-characterized group of patients with SSc.

METHOD

Twelve patients with SSc reporting reflux or dysphagia (11 women, median age 53 [range 35-72], duration of disease: 1-20 years) were investigated using distensibility testing of the EGJ. Patients were compared with 11 healthy volunteers (HV) (10 women, median age 53 [range 40-68]). The pressure and minimum diameter along the EGJ during ramp distension were used for distensibility analysis.

KEY RESULTS

Patients with SSc had significantly lower EGJ yield pressure (median: 4.0 mm Hg [Inter Quartile Range (IQR): 2.8-7.7]) than HV (median: 6.2 mm Hg [IQR: 9.4-26]) (P=.007). Likewise, the pressure-strain elastic modulus was lower in SSc patients (median 1.73 kPa [IQR: 1.16-2.15]) than in HV (median 2.41 kPa [IQR: 1.85-2.67]) (P=.03), indicating the reduced resistance to distension in SSc patient.

CONCLUSION & INFERENCES

Patients with SSc and symptoms of reflux and dysphagia have significantly reduced resistance to distension of the EGJ.

Abstract LB-266: DAXX promotes de novo lipogenesis in triple-negative breast cancer

Triple-negative breast cancers (TNBCs), defined by the absence of ER and PR expression and the lack of HER2 amplification, have no targeted treatment options, are highly aggressive, and exhibit poor prognosis. Identification of drivers and associated signaling pathways, particularly for TNBCs, is needed to assist the development of targeted therapies, to prolong disease-free survival, and to improve clinical outcome for cancer patients. Using high-throughput microarray-based global transcriptome profiling, we found that transcriptional regulator DAXX depletion strikingly impaired while DAXX overexpression enhanced the expression of genes in the de novo lipogenesis pathways in TNBCs cell line. Consistently, unbiased global metabolomics and lipidomics profiling by Ultra-High performance Liquid Chromatography coupled High-Resolution Mass Spectrometry (UHPLC-HRMS) also revealed that DAXX promotes de novo lipogenesis in both TNBC cell line as well as in corresponding xenograft tumors. In analyzing large number of genomic datasets including The Cancer Genome Atlas (TCGA), MolEcular Taxonomy of BReast cancer International Consortium (METABRIC), and The Cancer Cell Line Encyclopedia (CCLE) dataset, we found that DAXX expression is significantly higher in TNBC tumor samples and cell lines, and also DAXX gene expression positively correlates with that of key lipogenesis enzymes. The role of DAXX in cancer metabolism is previously unknown. Our integrated OMICs data analysis thus indicates that DAXX promotes de novo lipogenesis in TNBC. The mechanism through which DAXX regulates lipid metabolism is being investigated in our laboratory. Overall, our study identifies a potentially important pathway driving TNBC progression and suggests potential therapeutic targets for treating this aggressive form of breast cancer that still lacks curative treatment options.

Citation Format: Iqbal Mahmud, Timothy J. Garrett, Daiqing Liao. DAXX promotes de novo lipogenesis in triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-266. doi:10.1158/1538-7445.AM2017-LB-266

Abstract 4132: Roles of the acetyltransferases CBP/p300 in breast cancer

Intrinsic drug resistance renders certain breast cancer (BC) patients unresponsive to standard-of-care therapies. For example, ~50% of patients with estrogen receptor-positive (ER+) tumors do not respond to endocrine therapies (ETs, e.g., tamoxifen). Acquired drug resistance is another cause for treatment failure and deadly relapse. Therefore, new strategies that tackle both intrinsic and acquired resistance are needed for improving clinical outcome for BC patients. ER-alpha, the defining factor for ER+ tumors, is an estrogen-activated transcription factor (TF) that drives tumor growth and progression. It critically depends on the coactivators CBP/p300 for gene expression underpinning tumor biology of ER+ subtypes that account for ~75% of all BC cases. Recent advances revealed that another hormone receptor, the androgen receptor (AR), is expressed in the majority of ER+ BCs as well as in a subset of ER- BCs. Evidence has shown that AR signaling is implicated in ET resistance. For the HER2-enriched tumors, high levels of AR expression correlate with poor prognosis. Similarly for ER-alpha, CBP/p300 act as key coactivators for AR-mediated gene expression. Additionally, other oncogenic TFs (e.g., beta-catenin/TCF and STAT3) also depend on CBP/p300 for gene activation. Importantly, these pathways are active in all BC subtypes, regardless of the hormone receptor status. CBP/p300 overexpression and heightened acetyltransferase activity are detected in clinical BC samples and correlate with disease progression. Thus, CBP/p300 represent attractive targets for developing novel therapies broadly applicable for treating all major BC subtypes. We have discovered a novel class of highly potent CBP/p300 inhibitors. Our previous studies indicated that this class of compounds is highly effective to suppress tumor growth in vivo using a xenograft mouse model. We will present genomic features of CBP/p300 in different breast cancer subtypes and experimental data underlying potential mechanisms by which CBP/p300 regulate oncogenic phenotypes, as well as effects of pharmacologic inhibition of CBP/p300 on sensitivity of breast cancer cells to standard anticancer therapeutics.

Citation Format: Iqbal Muhmud, Guimei Tian, Daiqing Liao. Roles of the acetyltransferases CBP/p300 in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4132. doi:10.1158/1538-7445.AM2017-4132