The Big Picture of Glioblastoma Malignancy: A Meta-Analysis of Glioblastoma Proteomics to Identify Altered Biological Pathways

Glioblastoma is a highly malignant cancer with no effective treatment. It is vital to elucidate the mechanisms which drive glioblastoma in order to identify therapeutic targets. The differences in protein expression between glioblastoma, grade I–III glioma, and normal brain tissue reflect the functional alterations driving malignancy. However, proteomic analysis of glioblastoma has been hampered by the heterogeneity of glioblastoma and the variety of methodology used in its study. To reduce these inconsistencies, we performed a meta-analysis of the literature published since 2015, including 14 datasets from eight papers comparing the whole proteome of glioblastoma to normal brain or grade I–III glioma. We found that 154 proteins were commonly upregulated and 116 proteins were commonly downregulated in glioblastoma compared to normal brain. Meanwhile, 240 proteins were commonly upregulated and 125 proteins were commonly downregulated in glioblastoma compared to grade I–III glioma. Functional enrichment analysis revealed upregulation of proteins involved in mRNA splicing and the immune system and downregulation of proteins involved in synaptic signaling and glucose and glutamine metabolism. The identification of these altered biological pathways provides a basis for deeper investigation in the pursuit of an effective treatment for glioblastoma

The Big Picture of Glioblastoma Malignancy: A Meta-Analysis of Glioblastoma Proteomics to Identify Altered Biological Pathways

Glioblastoma is a highly malignant cancer with no effective treatment. It is vital to elucidate the mechanisms which drive glioblastoma in order to identify therapeutic targets. The differences in protein expression between glioblastoma, grade I–III glioma, and normal brain tissue reflect the functional alterations driving malignancy. However, proteomic analysis of glioblastoma has been hampered by the heterogeneity of glioblastoma and the variety of methodology used in its study. To reduce these inconsistencies, we performed a meta-analysis of the literature published since 2015, including 14 datasets from eight papers comparing the whole proteome of glioblastoma to normal brain or grade I–III glioma. We found that 154 proteins were commonly upregulated and 116 proteins were commonly downregulated in glioblastoma compared to normal brain. Meanwhile, 240 proteins were commonly upregulated and 125 proteins were commonly downregulated in glioblastoma compared to grade I–III glioma. Functional enrichment analysis revealed upregulation of proteins involved in mRNA splicing and the immune system and downregulation of proteins involved in synaptic signaling and glucose and glutamine metabolism. The identification of these altered biological pathways provides a basis for deeper investigation in the pursuit of an effective treatment for glioblastoma

Total Synthesis of Aigialomycin D Using a Ramberg−Bäcklund/RCM Strategy

The bioactive resorcylic acid lactone aigialomycin D (1) has been synthesized by a novel combination of ring-closing metathesis (RCM) and Ramberg−Bäcklund reactions. This synthetic strategy enables the C1′−C2′ alkene to be masked as a sulfone during formation of the macrocycle by ring closing metathesis at the C7′−C8′ olefin, thus avoiding competing formation of a cyclohexene. A subsequent Ramberg−Bäcklund reaction efficiently produces the C1′−C2′ E-alkene. This combined RCM/Ramberg−Bäcklund reaction strategy should be widely applicable to the synthesis of macrocyclic dienes

Mechanistic Studies on the Base-Promoted Ring Opening of Glycal-Derived <i>gem</i>-Dibromocyclopropanes

In the presence of a nucleophilic base, ring-fused gem-dibromocyclopropanes derived from d-glycals undergo ring opening to give 2-deoxy-2-(E-bromomethylene)­glycosides. Such cleavage of an exocyclic cyclopropane bond contrasts with the more usual silver-promoted ring-expansion reactions in which endocyclic bond cleavage occurs. Experimental and theoretical studies are reported which provide insights into the reaction mechanism and the origin of its kinetic selectivity for E-configured bromoalkene products. Density functional theory computations (M06-2X) predict that the reaction commences with alkoxide-induced HBr elimination from the dibromocyclopropane to form a bromocyclopropene. Ring opening then gives a configurationally stable zwitterionic (oxocarbenium cation/vinyl carbanion) intermediate, which undergoes nucleophilic addition and protonation to give the bromoalkene. There are two competing sources of the proton in the final step: One is the alcohol (co)­solvent, and the other is the molecule of alcohol produced during the initial deprotonation step. The roles of the formed alcohol molecule and the bulk (co)­solvent are demonstrated by isotope-labeling studies performed with deuterated solvents. The acid-promoted isomerization of the E-bromoalkene product into the corresponding Z-bromoalkene is also described. The mechanistic knowledge gained in this investigation sheds light on the unusual chemistry of this system and facilitates its future application in new settings

Mechanistic Studies on the Base-Promoted Ring Opening of Glycal-Derived <i>gem</i>-Dibromocyclopropanes

In the presence of a nucleophilic base, ring-fused gem-dibromocyclopropanes derived from d-glycals undergo ring opening to give 2-deoxy-2-(E-bromomethylene)­glycosides. Such cleavage of an exocyclic cyclopropane bond contrasts with the more usual silver-promoted ring-expansion reactions in which endocyclic bond cleavage occurs. Experimental and theoretical studies are reported which provide insights into the reaction mechanism and the origin of its kinetic selectivity for E-configured bromoalkene products. Density functional theory computations (M06-2X) predict that the reaction commences with alkoxide-induced HBr elimination from the dibromocyclopropane to form a bromocyclopropene. Ring opening then gives a configurationally stable zwitterionic (oxocarbenium cation/vinyl carbanion) intermediate, which undergoes nucleophilic addition and protonation to give the bromoalkene. There are two competing sources of the proton in the final step: One is the alcohol (co)­solvent, and the other is the molecule of alcohol produced during the initial deprotonation step. The roles of the formed alcohol molecule and the bulk (co)­solvent are demonstrated by isotope-labeling studies performed with deuterated solvents. The acid-promoted isomerization of the E-bromoalkene product into the corresponding Z-bromoalkene is also described. The mechanistic knowledge gained in this investigation sheds light on the unusual chemistry of this system and facilitates its future application in new settings

Mechanistic Studies on the Base-Promoted Ring Opening of Glycal-Derived <i>gem</i>-Dibromocyclopropanes

In the presence of a nucleophilic base, ring-fused gem-dibromocyclopropanes derived from d-glycals undergo ring opening to give 2-deoxy-2-(E-bromomethylene)­glycosides. Such cleavage of an exocyclic cyclopropane bond contrasts with the more usual silver-promoted ring-expansion reactions in which endocyclic bond cleavage occurs. Experimental and theoretical studies are reported which provide insights into the reaction mechanism and the origin of its kinetic selectivity for E-configured bromoalkene products. Density functional theory computations (M06-2X) predict that the reaction commences with alkoxide-induced HBr elimination from the dibromocyclopropane to form a bromocyclopropene. Ring opening then gives a configurationally stable zwitterionic (oxocarbenium cation/vinyl carbanion) intermediate, which undergoes nucleophilic addition and protonation to give the bromoalkene. There are two competing sources of the proton in the final step: One is the alcohol (co)­solvent, and the other is the molecule of alcohol produced during the initial deprotonation step. The roles of the formed alcohol molecule and the bulk (co)­solvent are demonstrated by isotope-labeling studies performed with deuterated solvents. The acid-promoted isomerization of the E-bromoalkene product into the corresponding Z-bromoalkene is also described. The mechanistic knowledge gained in this investigation sheds light on the unusual chemistry of this system and facilitates its future application in new settings

Mechanistic Studies on the Base-Promoted Ring Opening of Glycal-Derived <i>gem</i>-Dibromocyclopropanes

In the presence of a nucleophilic base, ring-fused gem-dibromocyclopropanes derived from d-glycals undergo ring opening to give 2-deoxy-2-(E-bromomethylene)­glycosides. Such cleavage of an exocyclic cyclopropane bond contrasts with the more usual silver-promoted ring-expansion reactions in which endocyclic bond cleavage occurs. Experimental and theoretical studies are reported which provide insights into the reaction mechanism and the origin of its kinetic selectivity for E-configured bromoalkene products. Density functional theory computations (M06-2X) predict that the reaction commences with alkoxide-induced HBr elimination from the dibromocyclopropane to form a bromocyclopropene. Ring opening then gives a configurationally stable zwitterionic (oxocarbenium cation/vinyl carbanion) intermediate, which undergoes nucleophilic addition and protonation to give the bromoalkene. There are two competing sources of the proton in the final step: One is the alcohol (co)­solvent, and the other is the molecule of alcohol produced during the initial deprotonation step. The roles of the formed alcohol molecule and the bulk (co)­solvent are demonstrated by isotope-labeling studies performed with deuterated solvents. The acid-promoted isomerization of the E-bromoalkene product into the corresponding Z-bromoalkene is also described. The mechanistic knowledge gained in this investigation sheds light on the unusual chemistry of this system and facilitates its future application in new settings

Synthesis of DNA-Directed Pyrrolidinyl and Piperidinyl Confined Alkylating Chloroalkylaminoanthraquinones: Potential for Development of Tumor-Selective <i>N</i>-Oxides

A novel series of 1,4-disubstituted chloroethylaminoanthraquinones, containing alkylating chloroethylamino functionalities as part of a rigid piperidinyl or pyrrolidinyl ring-system, have been prepared. The target compounds were prepared by ipso-displacement of halides of various anthraquinone chromophores by either hydroxylated or chlorinated piperidinyl- or pyrrolidinyl-alkylamino side chains. The chloroethylaminoanthraquinones were shown to alkylate guanine residues of linearized pBR322 (1−20 μM), and two symmetrically 1,4-disubstituted anthraquinones (compounds 14 and 15) were shown to interstrand cross-link DNA in the low nM range. Several 1,4-disubstituted chloroethylaminoanthraquinones were potently cytotoxic (IC50 values:  ≤40 nM) in human ovarian cancer A2780 cells. Two agents (compounds 18 and 19) exhibited mean GI50 values of 96 nM and 182 nM, respectively, in the NCI human tumor cell line panel. Derivatization of the potent DNA cross-linking agent 15 to an N-oxide resulted in loss of the DNA unwinding, DNA interstrand cross-linking and cytotoxic activity of the parent molecule

Synthesis and Biological Evaluation of Novel Chloroethylaminoanthraquinones with Potent Cytotoxic Activity against Cisplatin-Resistant Tumor Cells

Novel 1- and 1,4-substituted chloroethylaminoanthraquinones with DNA binding and alkylating properties along with their respective hydroxyethylaminoanthraquinone intermediates were synthesized. Selected chloroethylaminoanthraquinones were shown to cross-link DNA and alkylate guanines (at low nM concentration) with a preference for reaction sites containing 5‘-PyG. A compound (Alchemix) with the bis-chloroethyl functionality confined to one side chain alkylated but did not cross-link DNA. All the 1,4-disubstituted chloroethylaminoanthraquinones were potently cytotoxic (nM IC50s) against cisplatin-resistant ovarian cancer cell lines