GLI1-Inducible Glucuronidation Targets a Broad Spectrum of Drugs

GLI1 polymorphisms influence remission rate and prognosis of young de novo acute myeloid leukemia patients treated with cytarabine-based chemotherapy

Acute myeloid leukemia (AML) is a highly heterogeneous hematological malignancy. Cytarabine (Ara-C)-based chemotherapy is the primary treatment for AML, but currently known prognostic risk stratification factors cannot fully explain the individual differences in outcome of patients. In this article, we reported that patients with homozygous GLI1 rs2228224 mutation (AA genotype) had a significantly lower complete remission rate than those with GG wild type (54.17% vs.76.02%, OR = 1.993, 95% CI: 1.062-3.504, P = 0.031). GLI1 rs2229300 T allele carriers had remarkably shorter overall survival (513 vs. 645 days, P = 0.004) and disease-free survival (342 vs. 456 days, P = 0.033) than rs2229300 GG carriers. Rs2229300 G > T variation increased the transcriptional activity of GLI1. CCND1, CD44 and PROM1 were potential target genes differentially regulated by GLI1 rs2229300. Our results demonstrated for the first time that GLI1 polymorphisms influence chemosensitivity and prognosis of young de novo AML patients treated with Ara-C.

Medicinal Chemistry and NMR Driven Discovery of Novel UDP-glucuronosyltransferase 1A Inhibitors That Overcome Therapeutic Resistance in Cells

The UDP glucuronosyltransferases (UGT) deactivate many therapeutics via glucuronidation while being required for clearance of normal metabolites and xenobiotics. There are 19 UGT enzymes categorized into UGT1A and UGT2B families based on sequence conservation. This presents a challenge in terms of targeting specific UGTs to overcome drug resistance without eliciting overt toxicity. Here, we identified for the first time that UGT1A4 is highly elevated in acute myeloid leukemia (AML) patients and its reduction corresponded to objective clinical responses. To develop inhibitors to UGT1A4, we leveraged previous NMR-based fragment screening data against the C-terminal domain of UGT1A (UGT1A-C). NMR and medicinal chemistry strategies identified novel chemical matter based on fragment compounds with the capacity to bind ∼20 fold more tightly to UGT1A-C (Kd ∼ 600 μM vs ∼30 μM). Some compounds differentially inhibited UGT1A4 versus UGT1A1 enzyme activity and restored drug sensitivity in resistant human cancer cells. NMR-based NOE experiments revealed these novel compounds recognised a region distal to the catalytic site suggestive of allosteric regulation. This binding region is poorly conserved between UGT1A and UGT2B C-terminal sequences, which otherwise exhibit high similarity. Consistently, these compounds did not bind to the C-terminal domain of UGT2B7 nor a triple mutant of UGT1A-C replaced with UGT2B7 residues in this region. Overall, we discovered a site on UGTs that can be leveraged to differentially target UGT1As and UGT2Bs, identified UGT1A4 as a therapeutic target, and found new chemical matter that binds the UGT1A C-terminus, inhibits glucuronidation and restores drug sensitivity.

1,3,8-Triazaspiro[4.5]decane Derivatives Inhibit Permeability Transition Pores through a FO-ATP Synthase c Subunit Glu119-Independent Mechanism That Prevents Oligomycin A-Related Side Effects

Permeability transition pore (PTP) molecular composition and activity modulation have been a matter of research for several years, especially due to their importance in ischemia reperfusion injury (IRI). Notably, c subunit of ATP synthase (Csub) has been identified as one of the PTP-forming proteins and as a target for cardioprotection. Oligomycin A is a well-known Csub interactor that has been chemically modified in-depth for proposed new pharmacological approaches against cardiac reperfusion injury. Indeed, by taking advantage of its scaffold and through focused chemical improvements, innovative Csub-dependent PTP inhibitors (1,3,8-Triazaspiro[4.5]decane) have been synthetized in the past. Interestingly, four critical amino acids have been found to be involved in Oligomycin A-Csub binding in yeast. However, their position on the human sequence is unknown, as is their function in PTP inhibition. The aims of this study are to (i) identify for the first time the topologically equivalent residues in the human Csub sequence; (ii) provide their in vitro validation in Oligomycin A-mediated PTP inhibition and (iii) understand their relevance in the binding of 1,3,8-Triazaspiro[4.5]decane small molecules, as Oligomycin A derivatives, in order to provide insights into Csub interactions. Notably, in this study we demonstrated that 1,3,8-Triazaspiro[4.5]decane derivatives inhibit permeability transition pores through a FO-ATP synthase c subunit Glu119-independent mechanism that prevents Oligomycin A-related side effects.

Chemotherapy-related hyperbilirubinemia in pediatric acute lymphoblastic leukemia: a genome-wide association study from the AIEOP-BFM ALL study group

BACKGROUND

Characterization of clinical phenotypes in context with tumor and host genomic information can aid in the development of more effective and less toxic risk-adapted and targeted treatment strategies. To analyze the impact of therapy-related hyperbilirubinemia on treatment outcome and to identify contributing genetic risk factors of this well-recognized adverse effect we evaluated serum bilirubin levels in 1547 pediatric patients with acute lymphoblastic leukemia (ALL) and conducted a genome-wide association study (GWAS).

PATIENTS AND METHODS

Patients were treated in multicenter trial AIEOP-BFM ALL 2000 for pediatric ALL. Bilirubin toxicity was graded 0 to 4 according to the Common Toxicity Criteria (CTC) of the National Cancer Institute. In the GWAS discovery cohort, including 650 of the 1547 individuals, genotype frequencies of 745,895 single nucleotide variants were compared between 435 patients with hyperbilirubinemia (CTC grades 1-4) during induction/consolidation treatment and 215 patients without it (grade 0). Replication analyses included 224 patients from the same trial.

RESULTS

Compared to patients with no (grade 0) or moderate hyperbilirubinemia (grades 1-2) during induction/consolidation, patients with grades 3-4 had a poorer 5-year event free survival (76.6 ± 3% versus 87.7 ± 1% for grades 1-2, P = 0.003; 85.2 ± 2% for grade 0, P < 0.001) and a higher cumulative incidence of relapse (15.6 ± 3% versus 9.0 ± 1% for grades 1-2, P = 0.08; 11.1 ± 1% for grade 0, P = 0.007). GWAS identified a strong association of the rs6744284 variant T allele in the UGT1A gene cluster with risk of hyperbilirubinemia (allelic odds ratio (OR) = 2.1, P = 7 × 10^- 8). TT-homozygotes had a 6.5-fold increased risk of hyperbilirubinemia (grades 1-4; 95% confidence interval (CI) = 2.9-14.6, P = 7 × 10^- 6) and a 16.4-fold higher risk of grade 3-4 hyperbilirubinemia (95% CI 6.1-43.8, P = 2 × 10^- 8). Replication analyses confirmed these associations with joint analysis yielding genome-wide significance (allelic OR = 2.1, P = 6 × 10^- 11; 95% CI 1.7-2.7). Moreover, rs6744284 genotypes were strongly linked to the Gilbert's syndrome-associated UGT1A1*28/*37 allele (r² = 0.70), providing functional support for study findings. Of clinical importance, the rs6744284 TT genotype counterbalanced the adverse prognostic impact of high hyperbilirubinemia on therapy outcome.

CONCLUSIONS

Chemotherapy-related hyperbilirubinemia is a prognostic factor for treatment outcome in pediatric ALL and genetic variation in UGT1A aids in predicting the clinical impact of hyperbilirubinemia.

TRIAL REGISTRATION

http://www.

CLINICALTRIALS

gov ; #NCT00430118.

The search for genetic dark matter and lessons learned from the journey

In this review, I describe our scientific journey to unearth the impact of RNA metabolism in cancer using the eukaryotic translation initiation factor eIF4E as an exemplar. This model allowed us to discover new structural, biochemical, and molecular features of RNA processing, and to reveal their substantial impact on cell physiology. This led us to develop proof-of-principle strategies to target these pathways in cancer patients leading to clinical benefit. I discuss the important role that the unexpected plays in research and the necessity of embracing the data even when it clashes with dogma. I also touch on the importance of equity, diversity and inclusion to the success of the scientific enterprise.

1H, 13C and 15N chemical shift assignments of the C-terminal domain of human UDP-Glucuronosyltransferase 2B7 (UGT2B7-C)

The human UDP-glucuronosyltransferase (UGT) family of enzymes catalyze the covalent addition of glucuronic acid to a wide range of compounds, generally rendering them inactive. Although important for clearance of environmental toxins and metabolites, UGT activation can lead to inappropriate glucuronidation of therapeutics underlying drug resistance. Indeed, 50% of medications are glucuronidated. To better understand this mode of resistance, we studied the UGT2B7 enzyme associated with glucuronidation of cancer drugs such as Tamoxifen and Sorafenib. We report 1H, 13C and 15N backbone (> 90%) and side-chain assignments (~ 78% completeness according to CYANA) for the C-terminal domain of UGT2B7 (UGT2B7-C). Given the biomedical importance of this family of enzymes, our assignments will provide a key tool for improving understanding of the biochemical basis for substrate selectivity and other aspects of enzyme activity. This in turn will inform on drug design to overcome UGT-related drug resistance.

Defining the Role of GLI/Hedgehog Signaling in Chemoresistance: Implications in Therapeutic Approaches

Insight into cancer signaling pathways is vital in the development of new cancer treatments to improve treatment efficacy. A relatively new but essential developmental signaling pathway, namely Hedgehog (Hh), has recently emerged as a major mediator of cancer progression and chemoresistance. The evolutionary conserved Hh signaling pathway requires an in-depth understanding of the paradigm of Hh signaling transduction, which is fundamental to provide the necessary means for the design of novel tools for treating cancer related to aberrant Hh signaling. This review will focus substantially on the canonical Hh signaling and the treatment strategies employed in different studies, with special emphasis on the molecular mechanisms and combination treatment in regard to Hh inhibitors and chemotherapeutics. We discuss our views based on Hh signaling's role in regulating DNA repair machinery, autophagy, tumor microenvironment, drug inactivation, transporters, epithelial-to-mesenchymal transition, and cancer stem cells to promote chemoresistance. The understanding of this Achilles' Heel in cancer may improve the therapeutic outcome for cancer therapy.

Stereochemistries and Biological Properties of Oligomycin A Diels-Alder Adducts

Oligomycin A is a potent antibiotic and antitumor agent. However, its applications are restricted by its high toxicity and low bioavailability. In this study, we obtained Oligomycin A Diels-Alder adducts with benzoquinone and N-benzylmaleimide and determined their absolute configurations by combining ¹H and ROESY NMR data with molecular mechanics conformational analysis and quantum chemical reaction modeling. The latter showed that adduct stereochemistry is controlled by hydrogen bonding of the Oligomycin A side-chain isopropanol moiety with the carbonyl group of the dienophile. Biological studies showed that the Diels-Alder modification of the Oligomycin A diene system resulted in a complex antiproliferative potential pattern. The synthesized adducts were determined to be more active against the triple-negative (ERα, PR, and HER2 negative) breast cancer cell line MDA-MB-231 and lung carcinoma cell line A-549 compared to Oligomycin A. Meanwhile, Oligomycin A was more potent against myeloid leukemia cell line K-562 and breast carcinoma cell line MCF-7 than its derivatives. Thus, modification of the diene moiety of Oligomycin A is a promising strategy for developing novel antitumor agents based on its scaffold.

UGT2B17 modifies drug response in chronic lymphocytic leukaemia

Background

High UGT2B17 is associated with poor prognosis in untreated chronic lymphocytic leukaemia (CLL) patients and its expression is induced in non-responders to fludarabine-containing regimens. We examined whether UGT2B17, the predominant lymphoid glucuronosyltransferase, affects leukaemic drug response and is involved in the metabolic inactivation of anti-leukaemic agents.

Methods

Functional enzymatic assays and patients’ plasma samples were analysed by mass-spectrometry to evaluate drug inactivation by UGT2B17. Cytotoxicity assays and RNA sequencing were used to assess drug response and transcriptome changes associated with high UGT2B17 levels.

Results

High UGT2B17 in B-cell models led to reduced sensitivity to fludarabine, ibrutinib and idelalisib. UGT2B17 expression in leukaemic cells involved a non-canonical promoter and was induced by short-term treatment with these anti-leukaemics. Glucuronides of both fludarabine and ibrutinib were detected in CLL patients on respective treatment, however UGT2B17 conjugated fludarabine but not ibrutinib. AMP-activated protein kinase emerges as a pathway associated with high UGT2B17 in fludarabine-treated patients and drug-treated cell models. The expression changes linked to UGT2B17 exposed nuclear factor kappa B as a key regulatory hub.

Conclusions

Data imply that UGT2B17 represents a mechanism altering drug response in CLL through direct inactivation but would also involve additional mechanisms for drugs not inactivated by UGT2B17.

UGT1A1 genotype influences clinical outcome in patients with intermediate-risk acute myeloid leukemia treated with cytarabine-based chemotherapy

The treatment of acute myeloid leukemia (AML) is adjusted according to cytogenetic risk factors and molecular markers. Cytarabine remains the main drug to treat AML, and several studies have explored the prognostic relevance of the genotype of cytarabine metabolizing enzymes in AML. Glucuronidation has been identified to be relevant in the cytarabine clearance, but there are still few data concerning the clinical impact of genetic polymorphisms known to condition the activity of UDP-glucuronosyl transferases in AML patients. Here we report the association between the UGT1A1 rs8175347 genotype and the clinical outcome of 455 intermediate-risk cytogenetic AML patients receiving cytarabine-based chemotherapy. Patients with the UGT1A1*28 homozygous variant (associated to a lower UGT1A1 activity) had a lower overall survival (OS) (25.8% vs. 45.5%; p: 0.004). Multivariate analysis confirmed this association (p: 0.008; HR: 1.79; 95% CI: 1.16-2.76). Subgroup analysis showed the negative effect of the UGT1A1*28 homozygous genotype on OS in women (14.8% vs. 52.7%; p: 0.001) but not in men. This lower OS was associated with longer neutropenia after consolidation chemotherapy and with higher mortality without previous relapse, suggesting an association between a low glucuronidation activity and mortal toxic events.

Emerging roles for UDP-glucuronosyltransferases in drug resistance and cancer progression

The best-known role of UDP-glucuronosyltransferase enzymes (UGTs) in cancer is the metabolic inactivation of drug therapies. By conjugating glucuronic acid to lipophilic drugs, UGTs impair the biological activity and enhance the water solubility of these agents, driving their elimination. Multiple clinical observations support an expanding role for UGTs as modulators of the drug response and in mediating drug resistance in numerous cancer types. However, accumulating evidence also suggests an influence of the UGT pathway on cancer progression. Dysregulation of the expression and activity of UGTs has been associated with the progression of several cancers, arguing for UGTs as possible mediators of oncogenic pathways and/or disease accelerators in a drug-naive context. The consequences of altered UGT activity on tumour biology are incompletely understood. They might be associated with perturbed levels of bioactive endogenous metabolites such as steroids and bioactive lipids that are inactivated by UGTs or through non-enzymatic mechanisms, thereby eliciting oncogenic signalling cascades. This review highlights the evidence supporting dual roles for the UGT pathway, affecting cancer progression and drug resistance. Pharmacogenomic testing of UGT profiles in patients and the development of therapeutic options that impair UGT actions could provide useful prognostic and predictive biomarkers and enhance the efficacy of anti-cancer drugs.