Citations

Background: The human Monoamine Transporters (hMATs), primarily including hSERT, hNET and hDAT, are important targets for the treatment of depression and other behavioral disorders with more than the availability of 30 approved drugs. Objective: This paper is to review the recent progress in the binding mode and inhibitory mechanism of hMATs inhibitors with the central or allosteric binding sites, for the benefit of future hMATs inhibitor design and discovery. The Structure-Activity Relationship (SAR) and the selectivity for hit/lead compounds to hMATs that are evaluated by in vitro and in vivo experiments will be highlighted. Methods: PubMed and Web of Science databases were searched for protein-ligand interaction, novel inhibitors design and synthesis studies related to hMATs. Results: Literature data indicate that since the first crystal structure determinations of the homologous bacterial Leucine Transporter (LeuT) complexed with clomipramine, a sizable database of over 100 experimental structures or computational models has been accumulated that now defines a substantial degree of structural variability hMATs-ligands recognition. In the meanwhile, a number of novel hMATs inhibitors have been discovered by medicinal chemistry with significant help from computational models. Conclusion: The reported new compounds act on hMATs as well as the structures of the transporters complexed with diverse ligands by either experiment or computational modeling have shed light on the poly-pharmacology, multimodal and allosteric regulation of the drugs to transporters. All of the studies will greatly promote the Structure-Based Drug Design (SBDD) of structurally novel scaffolds with high activity and selectivity for hMATs.

TPS592 Background: Persistent cell proliferation (Ki67 > 10%) on tumor biopsies as early as 2-4 weeks (wks) on neo endocrine therapy (ET) identifies resistant tumors in ~20% patients (pts) with early stage ER+ HER2- BC who are at high risk of relapse. Palbo plus ET significantly improves progression free survival in pts with ET naïve or resistant advanced ER+ HER2- BC, and is being evaluated in the adjuvant setting. However, biomarkers predictive of palbo sensitivity are unknown. Ki67 analysis of serial tumor biopsies in the neo palbo and ana (NeoPalAna) trial demonstrated that 2 wks of palbo plus ana potently inhibited Ki67 and induced complete cell cycle arrest (CCCA, Ki67≤2.7%) in tumors with high Ki67 post 4 wks ana run-in. This study is therefore aimed to prospectively investigate the biological activity of palbo plus ana in ET resistant ER+ HER2- BC. Methods: The primary objective is to assess the rate of CCCA (central Ki67 ≤2.7%) after 2 wks of neo palbo and ana. Secondary objectives include analysis of tumor biopsies to explore response biomarkers. Key inclusions include women with clinical stage 2/3 ER+ HER2- BC, central Ki67 > 10% after ≥2 wks of any neo ET, adequate organ function. Key exclusions include prior CDK 4/6 inhibitor, treatment of BC except ET, concomitant use of strong CYP3A4 inhibitor. Pts receive palbo (125mg PO daily, days 1-21, 28-day cycle), ana (1 mg PO daily) and goserelin (if premenopausal). Pts with C1D15 Ki67 > 10% will discontinue study. If C1D15 Ki67 ≤10%, pt will receive 4 cycles of treatment, and additional 10-12 days of palbo if counts normalized within 3 wks post C4D28. Following surgery, pts are eligible for 2 years of adjuvant palbo. A sample size of 37 (stage 1, n = 12, stage 2 n = 25) by simon optimal two stage phase II design will be employed to assess whether the rate of CCCA is ≤5% vs ≥20% (90% power, alpha 0.1). Stage 2 will proceed if ≥1 had CCCA in stage 1. If ≤3 of 37 had CCCA, this regimen will be considered ineffective. The study is active and has enrolled 4 pts. Clinical trial information: NCT01723774.

Abstract Lung cancer has the highest mortality across all cancers in the world. Epidermal growth factor receptor (EGFR) is commonly mutated in lung adenocarcinomas from Asian non-smoking females. These tumors usually respond to EGFR tyrosine kinase inhibitors (EGFR-TKI), but the outcomes vary in different patients. Though EGFR T790M, amplification of MET and other mechanisms have been shown to confer EGFR-TKI resistance, the molecular mechanisms in around 30% of patients are still unknown. To uncover novel candidate pathways of EGFR-TKI resistance, we analyzed the whole exome mutation profiles of pre-treatment, EGFR T790M-free lung adenocarcinomas with typical activating mutations (L858R, exon 19 deletions). Amongst 19 non-responding (NR) tumors without significant shrinkage after gefitinib or erlotinib treatment, 67 cancer-related genes showed coding region non-synonymous single nucleotide variations (SNV) or insertion-deletions (indels) but they were not detected in 22 responding tumors. Gene set enrichment analysis (GSEA) showed 14 of the 67 genes were involved in the EGFR and WNT signaling network (false discovery rate q=1.14 e-8 for EGFR and q=4.3 e-9 for WNT), including well-known TKI resistance-related genes PIK3CA, PTEN and NF1. Notably, ARID1A, which encodes a subunit of the chromatin remodeling complex, showed nonsense mutations in 2 NR but not responding tumors, which were validated by Sanger sequencing. More than 40% of ARID1A mutations in lung adenocarcinomas recorded in COSMIC were nonsense mutations or frameshift indels. Loss of function mutations of ARID1A have also been reported in various cancers, together suggesting ARID1A might be a tumor suppressor but its involvement in EGFR mutant lung cancers is unknown. To investigate the potential role of ARID1A, its expression was first studied using Kaplan-Meier plotter. Low expression of ARID1A is associated with significantly better overall survival than high expression level in lung adenocarcinoma patients (p=8.5 e-7). To test whether loss of ARID1A could cause TKI resistance, ARID1A was knocked down by shRNA in HCC827 lung cancer cell line harboring EGFR exon19 deletion. MTT cell viability assay using gefitinib showed increase of IC50. Western blot assay further showed ARID1A knockdown increased phosphorylation of AKT at Ser473. Together, the findings suggest loss of ARID1A could lead to EGFR bypass and promote activation of the downstream PI3K/AKT pathway, leading to EGFR TKI resistance. Overall, our findings suggest EGFR-TKI resistance mutations could be detected before TKI drug selection. Resistant gene mutations present in pre-treatment tumors could help to predict the treatment response. More specifically, our study identified a promising gene list involved in EGFR-TKI resistance, and suggested ARID1A loss could be a novel EGFR-TKI resistance mechanism. Citation Format: Xuyuan Gao, Hang Xu, James CM Ho, Oscar SH Chan, Feng Xu, Junwen Wang, Victor HF Lee, Vicky PC Tin, Zhijie Xiao, Siqi Wang, Judy WP Yam, Maria P Wong. EGFR-mutant lung adenocarcinomas mutation profiles reveal ARID1A might be a novel tyrosine kinase resistance pathway [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-196.

Abstract1q21 gain is a common cytogenetic abnormality featuring high‐risk multiple myeloma (HRMM). However, the molecular mechanism underlying the adverse prognostic effect of 1q21 gain remains largely unclear. Here, we report that ARNT/HIF‐1β, a 1q21 gene, is highly expressed in HRMM and induced by microenvironmental hypoxia, which confers drug resistance and correlates with inferior outcome. Analysis of the gene expression profile database revealed that ARNT expression was upregulated in MM and increased with disease progression or in HRMM subtypes (particularly 1q21 gain), while correlated to shorter overall survival. In a cohort of 40 MM patients, qPCR further validated that ARNT expression was higher in MM patients than normal donors. MM cells carrying 1q21 gain or acquired drug resistance displayed a robust increase in HIF‐1β protein level. Hypoxia induced HIF‐1β expression via a NF‐κB‐dependent process. Notably, HIF‐1β overexpression impaired bortezomib sensitivity, whereas shRNA knockdown of ARNT reversed hypoxia‐mediated drug resistance. Together, these findings suggest that ARNT/HIF‐1β might represent a novel biomarker for risk stratification and prognosis of HRMM patients, as well as a potential therapeutic target for overcoming 1q21 gain‐ or microenvironment‐mediated and acquired drug resistance in MM.

Clearance of protein-bound uremic toxins (PBUTs) by dialysis is a challenge in the treatment of uremic patients. Shen-Shuai-Ning (SSN), a traditional Chinese medicine formulation, has been used commonly in China to retard kidney disease progression and decrease uremic toxins in chronic kidney disease (CKD) patients, but the effects of SSN on serum PBUTs in dialysis patients were not investigated. We conducted a randomized controlled trial in patients on peritoneal dialysis (PD) at dialysis center of Changzheng Hospital to evaluate the effects of SSN on serum PBUTs. Participants with SSN intervention took 5 g SSN granule three times daily for 12 weeks, while the baseline medications and dialysis prescriptions remained during the study in all patients. The serum concentrations of indoxyl sulphate (IS) and p-cresol sulphate (PCS) were determined by HPLC/MS/MS and biochemical parameters were assessed during the study. Sixty PD patients were enrolled and randomly allocated into SSN group and control group. Total IS level was significantly lower in SSN group than in control group at week 4, 8, and 12 (27.28 ± 18.19, 29.73 ± 19.10, and 29.41 ± 17.61 mg/l compared with 39.25 ± 20.23, 44.86 ± 23.91, and 45.34 ± 33.52 mg/l, respectively). However, there were no statistical difference of total PCS, free forms of IS and PCS concentrations between SSN group and control group during 12 weeks follow-up. Administration of SSN granule orally decreased serum total IS level effectively in uremic patients on PD with good tolerance. Benefits of PD patients’ outcomes from IS reduction by SSN awaits further large size and long duration clinical trials to verify.

Significance ES cells possess the unique capacity to self-renew as well as differentiate into specialized cell types. It is known that transcription factors and chromatin regulators regulate the cell-fate choices during differentiation. We report unexpectedly that Asf1a, a histone chaperone involved in nucleosome assembly, regulates mouse ES cell differentiation. Mechanistically, we show that Asf1a functions in nucleosome disassembly to resolve the bivalent chromatin domains at lineage-specific genes for gene activation during differentiation. These insights will likely be applicable for understanding human ES cell differentiation and regenerative medicine.

Abstract Researchers hypothesized that telomere shortening facilitates carcinogenesis. Previous studies found inconsistent associations between blood leukocyte telomere length (LTL) and cancer. Epigenetic reprogramming of telomere maintenance mechanisms may help explain this inconsistency. We examined associations between DNA methylation in telomere-related genes (TRG) and cancer. We analyzed 475 participants providing 889 samples 1 to 3 times (median follow-up, 10.1 years) from 1999 to 2013 in the Normative Aging Study. All participants were cancer-free at each visit and blood leukocytes profiled using the Illumina 450K array. Of 121 participants who developed cancer, 34 had prostate cancer, 10 melanoma, 34 unknown skin malignancies, and 43 another cancer. We examined 2,651 CpGs from 80 TRGs and applied a combination of Cox and mixed models to identify CpGs prospectively associated with cancer (at FDR < 0.05). We also explored trajectories of DNA methylation, logistic regression stratified by time to diagnosis/censoring, and cross-sectional models of LTL at first blood draw. We identified 30 CpGs on 23 TRGs whose methylation was positively associated with cancer incidence (β = 1.0–6.93) and one protective CpG in MAD1L1 (β = −0.65), of which 87% were located in TRG promoters. Methylation trajectories of 21 CpGs increased in cancer cases relative to controls; at 4 to 8 years prediagnosis/censoring, 17 CpGs were positively associated with cancer. Three CpGs were cross-sectionally associated with LTL. TRG methylation may be a mechanism through which LTL dynamics reflect cancer risk. Future research should confirm these findings and explore potential mechanisms underlying these findings, including telomere maintenance and DNA repair dysfunction. Cancer Prev Res; 11(8); 511–22. ©2018 AACR.