Development of a Novel Therapeutic Strategy for Estrogen Receptor Negative Breast Cancer

Estrogen receptor-α negative (ERα-) tumours are a highly aggressive and heterogeneous class of breast cancer (BC) with higher prevalence in younger women. ERα- BC is associated with a worse prognosis and limited therapeutic options. Therefore, discovery of new therapeutic targets is a clinical imperative. This thesis investigated three therapeutic targets for ERα- BC: the androgen receptor (AR), transcription factor AP-2β (TFAP-2β) and cyclin-dependent kinase 9 (CDK9). AR is expressed in 20-50% of ERα- BC, but preclinical evidence about its role is equivocal, indicating both proliferative and anti-proliferative effects. To inform this controversy, genomic parameters associated with differential AR-mediated growth effects were examined in two ERα-/AR+ breast cancer cell lines with differing proliferative responses to the natural AR ligand 5α-dihydrotestosterone (DHT). Comparing the AR-regulated transcriptome of MDA-MB-453 (growth stimulated by DHT) with MFM-223 (growth inhibited by DHT) breast cancer cells revealed that DHT regulates a discrete set of genes associated with distinct biological functions in the two models. DHT increased expression of genes associated with metabolism, development, and cell growth in MDA-MB-453 cells. In MFM-223 cells, DHT induced expression of genes with tumour suppressor activity. Analysis of AR cistrome showed that lack of AR enrichment at tumour suppressor genes exclusively upregulated by DHT in MFM-223 cells did not explain the inability of AR to induce transcription of these genes in MDA-MB-453 cells. We therefore hypothesised that differential DHT-regulated transcriptomes are driven by distinct interactions with AR co-regulatory proteins. Unbiased proteomic analysis of the AR interactomes identified TFAP-2β as a candidate factor of interest. High TFAP-2β expression specifically clustered molecular apocrine tumours (ERα-/AR+/HER2+) and TFAP-2β was required to sustain proliferative capacity, cell viability and expression of C-MYC and HER2 oncogenes in a representative cell line. Cistrome analysis revealed substantial co-localization of TFAP-2β and AR (at approximately 40% of total loci) following treatment with DHT. However, this interaction was not a critical determinant of oncogenic AR signalling. We conclude that TFAP-2β has AR-independent oncogenic effects and represents a novel new target for the molecular apocrine sub-type of ERα- BC. CDK9 is a transcriptional cyclin that increases RNA Polymerase II (RNAPII) activity to sustain expression of normally short-lived oncogenic and anti-apoptotic proteins. Targeting CDK9 has been hampered by poor selectivity of existing inhibitors (CDK9i). Here, we report a novel CDK9i, D-11, which exhibited high potency against CDK9 (Ki=8nM) and displayed remarkable selectivity over other CDKs and 369 human kinases. D-11 suppressed proliferation and triggered apoptosis in ERα- BC cells and these effects were ascribed to the reduction of p-RNAPII, C-MYC and MCL1 levels, indicative of targeted CDK9 inhibition. In vivo, D-11 inhibited ERα- BC tumour growth without affecting body weight or histology of normal tissues, indicating its potential for clinical translation as a treatment for ERα- BC. Overall, this thesis expands current knowledge about targeting AR in ERα- BCs, provides preclinical evidence to support TFAP-2β as a novel therapeutic target and D-11 as a highly selective, non-toxic CDK9 inhibitor ready for clinical development.Thesis (Ph.D.) -- University of Adelaide, Adelaide Medical School, 202

Modelling esophageal adenocarcinoma and Barrett’s esophagus with patient-derived organoids

Currently, esophageal adenocarcinoma (EAC) research is hindered by a dearth of adequate models to study this disease. Traditional cell line and genetically engineered mouse models are lacking in biological and physiological significance, whilst the inefficiency of patient-derived xenografts limit their potential applications. This review describes the landscape of EAC research using patient-derived organoids (PDOs). Here, we detail the methods of establishment and optimization of EAC PDO cultures, as well as current and prospective applications of these models. We further highlight a crucial knowledge gap in the mechanisms of EAC transformation from its precursor lesion, Barrett’s esophagus (BE). As such, we also describe the culture requirements of BE PDOs and attempts to model tumorigenesis using PDO models

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

Arabic Phonetic Rules

Description: this xml file describes the Arabic phonetic constraints (rules) resulting from the analysis of the lexicons(Taj Alarous, Al ain, Lisan Al arab, Alwassit and almoassir ). These rules are to be applied to Arabic roots and are classified into a number of categories. Each category has a certain type of constraints as follow: The first category defines that the root must not consist of three identical letters. The second category defines that the root must not start with two repeating letters. The third category lists the letters that must not occur in the same root, regardless of their order. The fourth category lists the letters that may not be used together in a certain order in a root. ISLRN: 190-535-098-473-

Addressed Arabic Phonetic Rules

This xml file describes the Arabic phonetic constraints are to be applied on Arabic root. The first rule category lists the letters that may not occur in the same root, regardless of their order. The second category lists the letters that may not be used together in a root word with a specific order. The third and fourth categories show that each contiguous letters must not be redundant ISLRN: 991-445-325-823-

Arabic Triliteral roots Lexicon

Description: This xml file is a lexicon containing all 21952 (28x28x28) Arabic triliteral combinations (roots). the file is split into three parts as follow: the first part contains the phonetic constraints that must be taken into account in the formation of Arabic roots (for more details see all_phonetic_rules.xml in http://arabic.emi.ac.ma/alelm/?q=Resources). the second part contains the lexicons that were used to create this lexicon (see in lexicons tag). the third part contains the roots. ISLRN: 813-907-570-946-

The cellular and molecular effects of the androgen receptor agonist, Cl-4AS-1, on breast cancer cells

<p><b>Purpose</b>: The androgen receptor (AR) has attracted attention in the treatment of breast cancer. Due to the undesirable side effects of AR agonists, attempts have been undertaken to develop selective AR modulators. One of these compounds is Cl-4AS-1. This study examined this compound more closely at the cellular and molecular levels. <b>Methods</b>: Three different breast cancer cell lines were utilized, namely the luminal MCF-7 cells, the molecular apocrine MDA-MB-453 cells, and the triple negative, basal MDA-MB-231 cells. <b>Results</b>: High and significant concordance between dihydrotestosterone (DHT) and Cl-4AS-1 in regulation of gene expression in MDA-MB-453 cells was found. However, some differences were noted including the expression of AR, which was upregulated by DHT, but not Cl-4AS-1. In addition, both DHT and Cl-4AS-1 caused a similar morphological change and reorganization of the actin structure of MDA-MB-453 cells into a mesenchymal phenotype. Treatment of cells with DHT resulted in induction of proliferation of MCF-7 and MDA-MB-453 cells, but no effect was observed on the growth of MDA-MB-231 cells. On the other hand, increasing doses of Cl-4AS-1 resulted in a dose-dependent inhibition on the growth of the three cell lines. This inhibition was a result of induction of apoptosis whereby Cl-4AS-1 caused a block in entry of cells into the S-phase followed by DNA degradation. <b>Conclusions</b>: These results indicate that although Cl-4AS-1 has characteristics of classical AR agonist, it has dissimilar properties that may make it useful in treating breast cancer.</p