One-Pot Radiosynthesis and Biological Evaluation of a Caspase-3 Selective 5-[123,125I]iodo-1,2,3-triazole derived Isatin SPECT Tracer.

Induction of apoptosis is often necessary for successful cancer therapy, and the non-invasive monitoring of apoptosis post-therapy could assist in clinical decision making. Isatins are a class of compounds that target activated caspase-3 during apoptosis. Here we report the synthesis of the 5-iodo-1,2,3-triazole (FITI) analog of the PET tracer [18F]ICMT11 as a candidate tracer for imaging of apoptosis with SPECT, as well as PET. Labelling with radioiodine (123,125I) was achieved in 55 ± 12% radiochemical yield through a chelator-accelerated one-pot cycloaddition reaction mediated by copper(I) catalysis. The caspase-3 binding affinity and selectivity of FITI compares favourably to that of [18F]ICMT11 (Ki = 6.1 ± 0.9 nM and 12.4 ± 4.7 nM, respectively). In biodistribution studies, etoposide-induced cell death in a SW1222 xenograft model resulted in a 2-fold increase in tumour uptake of the tracer. However, the tumour uptake was too low to allow in vivo imaging of apoptosis with SPECT.

Targeting Multiple Effector Pathways in Pancreatic Ductal Adenocarcinoma with a G-Quadruplex-Binding Small Molecule.

Human pancreatic ductal adenocarcinoma (PDAC) involves the dysregulation of multiple signaling pathways. A novel approach to the treatment of PDAC is described, involving the targeting of cancer genes in PDAC pathways having over-representation of G-quadruplexes, using the trisubstituted naphthalene diimide quadruplex-binding compound 2,7-bis(3-morpholinopropyl)-4-((2-(pyrrolidin-1-yl)ethyl)amino)benzo[ lmn][3,8]phenanthroline-1,3,6,8(2 H,7 H)-tetraone (CM03). This compound has been designed by computer modeling, is a potent inhibitor of cell growth in PDAC cell lines, and has anticancer activity in PDAC models, with a superior profile compared to gemcitabine, a commonly used therapy. Whole-transcriptome RNA-seq methodology has been used to analyze the effects of this quadruplex-binding small molecule on global gene expression. This has revealed the down-regulation of a large number of genes, rich in putative quadruplex elements and involved in essential pathways of PDAC survival, metastasis, and drug resistance. The changes produced by CM03 represent a global response to the complexity of human PDAC and may be applicable to other currently hard-to-treat cancers.

A G-quadruplex-binding compound showing anti-tumour activity in an in vivo model for pancreatic cancer.

We report here that a tetra-substituted naphthalene-diimide derivative (MM41) has significant in vivo anti-tumour activity against the MIA PaCa-2 pancreatic cancer xenograft model. IV administration with a twice-weekly 15 mg/kg dose produces ca 80% tumour growth decrease in a group of tumour-bearing animals. Two animals survived tumour-free after 279 days. High levels of MM41 are rapidly transported into cell nuclei and were found to accumulate in the tumour. MM41 is a quadruplex-interactive compound which binds strongly to the quadruplexes encoded in the promoter sequences of the BCL-2 and k-RAS genes, both of which are dis-regulated in many human pancreatic cancers. Levels of BCL-2 were reduced by ca 40% in tumours from MM41-treated animals relative to controls, consistent with BCL-2 being a target for MM41. Molecular modelling suggests that MM41 binds to a BCL-2 quadruplex in a manner resembling that previously observed in co-crystal structures with human telomeric quadruplexes. This supports the concept that MM41 (and by implication other quadruplex-targeting small molecules) can bind to quadruplex-forming promoter regions in a number of genes and down-regulate their transcription. We suggest that quadruplexes within those master genes that are up-regulated drivers for particular cancers, may be selective targets for compounds such as MM41.

A whole-body dual-modality radionuclide optical strategy for preclinical imaging of metastasis and heterogeneous treatment response in different microenvironments.

UNLABELLED: Imaging spontaneous cancer cell metastasis or heterogeneous tumor responses to drug treatment in vivo is difficult to achieve. The goal was to develop a new highly sensitive and reliable preclinical longitudinal in vivo imaging model for this purpose, thereby facilitating discovery and validation of anticancer therapies or molecular imaging agents. METHODS: The strategy is based on breast cancer cells stably expressing the human sodium iodide symporter (NIS) fused to a red fluorescent protein, thereby permitting radionuclide and fluorescence imaging. Using whole-body nano-SPECT/CT with (99m)TcO4(-), we followed primary tumor growth and spontaneous metastasis in the presence or absence of etoposide treatment. NIS imaging was used to classify organs as small as individual lymph nodes (LNs) to be positive or negative for metastasis, and results were confirmed by confocal fluorescence microscopy. Etoposide treatment efficacy was proven by ex vivo anticaspase 3 staining and fluorescence microscopy. RESULTS: In this preclinical model, we found that the NIS imaging strategy outperformed state-of-the-art (18)F-FDG imaging in its ability to detect small tumors (18.5-fold-better tumor-to-blood ratio) and metastases (LN, 3.6-fold) because of improved contrast in organs close to metastatic sites (12- and 8.5-fold-lower standardized uptake value in the heart and kidney, respectively). We applied the model to assess the treatment response to the neoadjuvant etoposide and found a consistent and reliable improvement in spontaneous metastasis detection. Importantly, we also found that tumor cells in different microenvironments responded in a heterogeneous manner to etoposide treatment, which could be determined only by the NIS-based strategy and not by (18)F-FDG imaging. CONCLUSION: We developed a new strategy for preclinical longitudinal in vivo cancer cell tracking with greater sensitivity and reliability than (18)F-FDG PET and applied it to track spontaneous and distant metastasis in the presence or absence of genotoxic stress therapy. Importantly, the model provides sufficient sensitivity and dynamic range to permit the reliable assessment of heterogeneous treatment responses in various microenvironments.

IL-23 and IL-12p70 production by monocytes and dendritic cells in primary HIV-1 infection.

IL-12 enhances protective responses against HIV replication. Its production after in vitro stimulation is defective in chronic HIV infection, but higher responses can be found. IL-23 shares the p40 chain and some properties with IL-12 and enhances Th17 responses, but its role in HIV infection is unknown. The production of IL-12 and IL-23 and the respective contribution of monocytes and myeloid conventional DC (cDCs) during primary HIV infection were determined. Sixteen patients included in the French PRIMO-ANRS Cohort without antiretroviral treatment were followed prospectively and compared with uninfected donors. Intracellular p40 expression by monocytes and cDCs, analyzed by flow cytometry, was transiently increased in monocytes and cDCs in response to LPS and more consistently, in monocytes in response to LPS + IFN-gamma. IL-23 production, measured by ELISA after PBMC stimulation, was induced by LPS in strong correlation with VLs. IL-12p70 production required the addition of IFN-gamma and was transiently increased in patients compared with controls in correlation with VLs, whereas IL-23 was increased sustainedly. Therefore, an apparent domination of IL-23 over IL-12 responses occurred throughout primary HIV infection, and a potential restoration of IL-12 responses might be expected from a treatment mimicking activated T cell signals.

Plasmacytoid dendritic cells accumulate in spleens from chronically HIV-infected patients but barely participate in interferon-alpha expression.

We characterized the localization, phenotype, and some functions of plasmacytoid dendritic cells (pDCs) in the human spleen. pDCs were localized in the marginal zone and the periarteriolar region. Some were also found in the red pulp. pDCs were immature by phenotypic labeling, consistently with their capacity to internalize Dextran in a functional assay. In spleens from HIV-infected patients with thrombocytopenic purpura, these characteristics were unaffected. However, an accumulation of pDCs, but not myeloid dendritic cells (mDCs), was observed in some HIV+ patients, correlating with high proviral loads. Moreover, although undetectable in most HIV- patients, interferon-alpha (IFN-alpha) production was evidenced in situ and by flow cytometry in most HIV+ patients. IFN-alpha was located in the marginal zone. Surprisingly, IFN-alpha colocalized only with few pDCs, but rather with other cells, including T and B lymphocytes, mDCs, and macrophages. Therefore, pDCs accumulated in spleens from HIV+ patients with high proviral loads, but they did not seem to be the main IFN-alpha producers.