Synthesis and biological studies of new piperidino-1,2,3-triazole hybrids with 3-aryl isoxazole side chains.

A small library of new piperidine-triazole hybrids with 3-aryl isoxazole side chains has been designed and synthesized. Their cytotoxicity against a panel of seven cancer cell lines has been established. For the most promising compound, an IC value of 3.

Glutamine uptake and utilization of human mesenchymal glioblastoma in orthotopic mouse model.

Background: Glioblastoma (GBM) are highly heterogeneous on the cellular and molecular basis. It has been proposed that glutamine metabolism of primary cells established from human tumors discriminates aggressive mesenchymal GBM subtype to other subtypes.

Methods: To study glutamine metabolism in vivo, we used a human orthotopic mouse model for GBM.

STING-dependent paracriny shapes apoptotic priming of breast tumors in response to anti-mitotic treatment.

A fascinating but uncharacterized action of antimitotic chemotherapy is to collectively prime cancer cells to apoptotic mitochondrial outer membrane permeabilization (MOMP), while impacting only on cycling cell subsets. Here, we show that a proapoptotic secretory phenotype is induced by activation of cGAS/STING in cancer cells that are hit by antimitotic treatment, accumulate micronuclei and maintain mitochondrial integrity despite intrinsic apoptotic pressure. Organotypic cultures of primary human breast tumors and patient-derived xenografts sensitive to paclitaxel exhibit gene expression signatures typical of type I IFN and TNFα exposure.

Targeting PUMA/Bcl-xL interaction by new specific compounds to unleash apoptotic process in cancer cells.

We describe the first examples of small molecules able to disrupt the nanomolar interaction between the pro-apoptotic protein PUMA and its anti-apoptotic counterpart BcL-xL in malignant cells. Based on molecular modelling studies, we propose a rationale to this result, through a new "bottle-opener"-type strategy which could be of general use in the area of protein-protein interaction studies.

Structure-guided design of pyridoclax derivatives based on Noxa / Mcl-1 interaction mode.

Protein-protein interactions are attractive targets because they control numerous cellular processes. In oncology, apoptosis regulating Bcl-2 family proteins are of particular interest. Apoptotic cell death is controlled via PPIs between the anti-apoptotic proteins hydrophobic groove and the pro-apoptotic proteins BH3 domain.

The oncogenic tyrosine kinase Lyn impairs the pro-apoptotic function of Bim.

Phosphorylation of Ser/Thr residues is a well-established modulating mechanism of the pro-apoptotic function of the BH3-only protein Bim. However, nothing is known about the putative tyrosine phosphorylation of this Bcl-2 family member and its potential impact on Bim function and subsequent Bax/Bak-mediated cytochrome c release and apoptosis. As we have previously shown that the tyrosine kinase Lyn could behave as an anti-apoptotic molecule, we investigated whether this Src family member could directly regulate the pro-apoptotic function of Bim.

E2F1 interacts with BCL-xL and regulates its subcellular localization dynamics to trigger cell death.

E2F1 is the main pro-apoptotic effector of the pRB-regulated tumor suppressor pathway by promoting the transcription of various pro-apoptotic proteins. We report here that E2F1 partly localizes to mitochondria, where it favors mitochondrial outer membrane permeabilization. E2F1 interacts with BCL-xL independently from its BH3 binding interface and induces a stabilization of BCL-xL at mitochondrial membranes.

BCL-X directly modulates RAS signalling to favour cancer cell stemness.

In tumours, accumulation of chemoresistant cells that express high levels of anti-apoptotic proteins such as BCL-X is thought to result from the counter selection of sensitive, low expresser clones during progression and/or initial treatment. We herein show that BCL-X expression is selectively advantageous to cancer cell populations even in the absence of pro-apoptotic pressure. In transformed human mammary epithelial cells BCL-X favours full activation of signalling downstream of constitutively active RAS with which it interacts in a BH4-dependent manner.

Efficient Mitochondrial Glutamine Targeting Prevails Over Glioblastoma Metabolic Plasticity.

Glioblastoma (GBM) is the most common and malignant form of primary human brain tumor in adults, with an average survival at diagnosis of 18 months. Metabolism is a new attractive therapeutic target in cancer; however, little is known about metabolic heterogeneity and plasticity within GBM tumors. We therefore aimed to investigate metabolic phenotyping of primary cultures in the context of molecular tumor heterogeneity to provide a proof of concept for personalized metabolic targeting of GBM.

Tight Sequestration of BH3 Proteins by BCL-xL at Subcellular Membranes Contributes to Apoptotic Resistance.

Anti-apoptotic BCL-2 family members bind to BH3-only proteins and multidomain BAX/BAK to preserve mitochondrial integrity and maintain survival. Whereas inhibition of these interactions is the biological basis of BH3-mimetic anti-cancer therapy, the actual response of membrane-bound protein complexes to these compounds is currently ill-defined. Here, we find that treatment with BH3 mimetics targeting BCL-xL spares subsets of cells with the highest levels of this protein.

Preliminary Studies on the Activity of Mixed Polyphenol-Heterocyclic Systems Against B16-F10 Melanoma Cancer Cells.

The Bcl-2 family includes 26 proteins involved in apoptosis. Cancer cells can develop the ability to avoid apoptosis through the upregulation and/or down regulation of such proteins Bax, Bcl-xL or Mcl-1, especially during chemoresistance progress. These proteins engaged in a network of dynamic interactions that control apoptosis triggering have become attractive therapeutic targets in cancers including melanoma.

TCTP contains a BH3-like domain, which instead of inhibiting, activates Bcl-xL.

Translationally Controlled Tumor Protein (TCTP) is anti-apoptotic, key in development and cancer, however without the typical Bcl2 family members' structure. Here we report that TCTP contains a BH3-like domain and forms heterocomplexes with Bcl-xL. The crystal structure of a Bcl-xL deletion variant-TCTP11-31 complex reveals that TCTP refolds in a helical conformation upon binding the BH3-groove of Bcl-xL, although lacking the h1-subregion interaction.

A combination of in silico and SAR studies to identify binding hot spots of Bcl-xL inhibitors.

Inhibition of Bcl-2 family protein-protein interactions (PPI) is a very promising direction in cancer chemotherapy. Hence over the last decade, many medicinal chemistry studies endeavoured to discover drug candidates, and a wealth of chemical scaffolds with striking chemical diversity was reported as Bcl-xL inhibitors. This raises the question of whether all these molecules could occupy a unique binding site, or rather discrete pockets of the protein surface.

First evidence that oligopyridines, α-helix foldamers, inhibit Mcl-1 and sensitize ovarian carcinoma cells to Bcl-xL-targeting strategies.

Apoptosis control defects such as the deregulation of Bcl-2 family member expression are frequently involved in chemoresistance. In ovarian carcinoma, we previously demonstrated that Bcl-xL and Mcl-1 cooperate to protect cancer cells against apoptosis and their concomitant inhibition leads to massive apoptosis even in the absence of chemotherapy. Whereas Bcl-xL inhibitors are now available, Mcl-1 inhibition, required to sensitize cells to Bcl-xL-targeting strategies, remains problematic.

Design, synthesis and biological evaluation of new inhibitors of Bax/Bcl-xL interaction in cancer cells.

We describe the synthesis of a series of new molecules containing phenol and triazoles moieties, compounds which have been evaluated for their ability to inhibit Bax/Bcl-xL interactions in cancer cells, by using BRET assays, and to induce cell death. Several derivatives exhibit a very promising activity, being more potent than the reference compounds acylpyrogallol A and ABT-737. These preliminary results demonstrate that derivatives of this family can be attractive to develop new molecules with potent anticancer activity.

Decoding and unlocking the BCL-2 dependency of cancer cells.

Cancer cells are subject to many apoptotic stimuli that would kill them were it not for compensatory prosurvival alterations. BCL-2-like (BCL-2L) proteins contribute to such aberrant behaviour by engaging a network of interactions that is potent at promoting survival but that is also fragile: inhibition of a restricted number of interactions may suffice to trigger cancer cell death. Currently available and novel compounds that inhibit these interactions could be efficient therapeutic agents if this phenotype of BCL-2L dependence was better understood at a molecular, cellular and systems level and if it could be diagnosed by relevant biomarkers.

Hemisynthesis of selected embelin analogs and investigation of their proapoptotic activity against cancer cells.

Embelin is a natural product, inhibitor of XIAP (X-chromosome-linked Inhibitor of APoptosis) with strong proapoptotic properties on cancer cells. In order to clarify the role of two OH groups on benzoquinone core, we have prepared by hemisynthesis close analogs of embelin, where these OH groups have been replaced in a systematic manner by OMe and OAc groups. Proapoptotic activities of six embelin derivatives have been studied as single agent, or in combination with TRAIL, and their abilities to interact with XIAP have been evaluated by Surface Plasmon Biacore.

Structure-activity relationship of selected polyphenol derivatives as inhibitors of Bax/Bcl-xL interaction.

This paper describes the synthesis of nine selected diaryl/heteroaryl-containing phenol and polyphenol derivatives which have been evaluated against Bax/Bcl-xL interaction in comparison with ABT-737. Using a BRET assay, six of these derivatives exhibit activity comparable to ABT-737 to disrupt Bax/Bcl-xL interaction. These preliminary results demonstrate that such polyphenol-derived molecules are attractive compounds regarding anticancer activity and that the phenol at position 3 is important regarding disruption of Bax/Bcl-xL interaction.

ABT-737 and/or folate reverse the PDGF-induced alterations in the mitochondrial apoptotic pathway in low-grade glioma patients.

Elevated activation of the platelet-derived growth factor (PDGF) pathway, apoptosis evasion phenotype, and global DNA hypomethylation are hallmarks frequently observed in cancers, such as in low-grade glioma (LGG). However, the orchestration of these malignant functions is not fully elucidated in LGG. Our study reveals that the co-presence of these hallmarks in the same LGG is frequent and confers poor prognosis in patients with LGG.

c-Myc dependent expression of pro-apoptotic Bim renders HER2-overexpressing breast cancer cells dependent on anti-apoptotic Mcl-1.

Background: Anti-apoptotic signals induced downstream of HER2 are known to contribute to the resistance to current treatments of breast cancer cells that overexpress this member of the EGFR family. Whether or not some of these signals are also involved in tumor maintenance by counteracting constitutive death signals is much less understood. To address this, we investigated what role anti- and pro-apoptotic Bcl-2 family members, key regulators of cancer cell survival, might play in the viability of HER2 overexpressing breast cancer cells.

Bax activation by the BH3-only protein Puma promotes cell dependence on antiapoptotic Bcl-2 family members.

It is still unclear whether the BH3-only protein Puma (p53 up-regulated modulator of apoptosis) can prime cells to death and render antiapoptotic BH3-binding Bcl-2 homologues necessary for survival through its ability to directly interact with proapoptotic Bax and activate it. In this study, we provide further evidence, using cell-free assays, that the BH3 domain of Puma binds Bax at an activation site that comprises the first helix of Bax. We also show that, in yeast, Puma interacts with Bax and triggers its killing activity when Bcl-2 homologues are absent but not when Bcl-xL is expressed.

Functional and physical interaction between Bcl-X(L) and a BH3-like domain in Beclin-1.

The anti-apoptotic proteins Bcl-2 and Bcl-X(L) bind and inhibit Beclin-1, an essential mediator of autophagy. Here, we demonstrate that this interaction involves a BH3 domain within Beclin-1 (residues 114-123). The physical interaction between Beclin-1 and Bcl-X(L) is lost when the BH3 domain of Beclin-1 or the BH3 receptor domain of Bcl-X(L) is mutated.

The small organic compound HA14-1 prevents Bcl-2 interaction with Bax to sensitize malignant glioma cells to induction of cell death.

A functional imbalance between proapoptotic Bax and antiapoptotic Bcl-2 is likely to participate in the resistance of cancer cells to therapy. We show here that ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate (HA14-1), a small organic compound recently proposed to function as an inhibitor of Bcl-2, increases the sensitivity of human glioblastoma cells to radiotherapy and chemotherapy. This sensitizing effect is lost if Bcl-2 expression, but not Bcl-xL expression, is knocked down or if cells only express a mutant of Bax that does not interact with Bcl-2.

The first alpha helix of Bax plays a necessary role in its ligand-induced activation by the BH3-only proteins Bid and PUMA.

The mechanism by which some BH3-only proteins of the Bcl-2 family directly activate the "multidomain" proapoptotic member Bax is poorly characterized. We report that the first alpha helix (Halpha1) of Bax specifically interacts with the BH3 domains of Bid and PUMA but not with that of Bad. Inhibition of this interaction, by a peptide comprising Halpha1 or by a mutation in this helix, prevents ligand-induced activation of Bax by Bid, PUMA, or their BH3 peptides.

ANT2 expression under hypoxic conditions produces opposite cell-cycle behavior in 143B and HepG2 cancer cells.

Under hypoxic conditions, mitochondrial ATP production ceases, leaving cells entirely dependent on their glycolytic metabolism. The cytoplasmic and intramitochondrial ATP/ADP ratios, partly controlled by the adenine nucleotide translocator (ANT), are drastically modified. In dividing and growing cells that have a predominantly glycolytic metabolism, the ANT isoform 2, which has kinetic properties allowing ATP import into mitochondria, is over-expressed in comparison to control cells.