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The omnipresent threat of tuberculosis (TB) and the scant treatment options thereof necessitate the development of new antitubercular agents, preferably working via a novel mechanism of action distinct from the current drugs. Various studies identified the mycobacterial membrane protein large 3 transporter (MmpL3) as the target of several classes of compounds, including the indole-2-caboxamides. Herein, several indoleamide analogues were rationally designed, synthesised, and evaluated for their antitubercular and antitumour activities. Compound 8g displayed the highest activity (MIC = 0.32 μM) against the drug-sensitive (DS) Mycobacterium tuberculosis (M. tb) H37Rv strain. This compound also exhibited high selective activity towards M. tb over mammalian cells [IC50 (Vero cells) = 40.9 μM, SI = 128], suggesting its minimal cytotoxicity. In addition, when docked into the MmpL3 active site, 8g adopted a binding profile similar to the indoleamide ligand ICA38. A related compound 8f showed dual antitubercular (MIC = 0.62 μM) and cytotoxic activities against paediatric glioblastoma multiforme (GBM) cell line KNS42 [IC50 (viability) = 0.84 μM]. Compound 8f also showed poor cytotoxic activity against healthy Vero cells (IC50 = 39.9 μM). Compounds 9a and 15, which were inactive against M. tb, showed potent cytotoxic (IC50 = 8.25 and 5.04 μM, respectively) and antiproliferative activities (IC50 = 9.85 and 6.62 μM, respectively) against KNS42 cells. Transcriptional analysis of KNS42 cells treated with compound 15 revealed a significant downregulation in the expression of the carbonic anhydrase 9 (CA9) and the spleen tyrosine kinase (SYK) genes. The expression levels of these genes in GBM tumours were previously shown to contribute to tumour progression, suggesting their involvement in our observed antitumour activities. Compounds 9a and 15 were selected for further evaluations against three different paediatric brain tumour cell lines (BT12, BT16 and DAOY) and non-neoplastic human fibroblast cells HFF1. Compound 9a showed remarkable cytotoxic (IC50 = 0.89 and 1.81 μM, respectively) and antiproliferative activities (IC50 = 7.44 and 6.06 μM, respectively) against the two tested atypical teratoid/rhabdoid tumour (AT/RT) cells BT12 and BT16. Interestingly, compound 9a was not cytotoxic when tested against non-neoplastic HFF1 cells [IC50 (viability) = 119 μM]. This suggests that an indoleamide scaffold can be fine-tuned to confer a set of derivatives with selective antitubercular and/or antitumour activities.

Paediatric glioblastomas are rapidly growing, devastating brain neoplasms with an invasive phenotype. Radiotherapy and chemotherapy, which are the current therapeutic adjuvant to surgical resection, are still associated with various toxicity profiles and only marginally improve the course of the disease and life expectancy. A considerable body of evidence supports the antitumour and apoptotic effects of certain cannabinoids, such as WIN55,212-2, against a wide spectrum of cancer cells, including gliomas. In fact, we previously highlighted the potent cytotoxic activity of the cannabinoid ligand 5 against glioblastoma KNS42 cells. Taken together, in this study, we designed, synthesised, and evaluated several indoles and indole bioisosteres for their antitumour activities. Compounds 8a, 8c, 8f, 12c, and 24d demonstrated significant inhibitory activities against the viability (IC(50) = 2.34–9.06 μM) and proliferation (IC(50) = 2.88–9.85 μM) of paediatric glioblastoma KNS42 cells. All five compounds further retained their antitumour activities against two atypical teratoid/rhabdoid tumour (AT/RT) cell lines. When tested against a medulloblastoma DAOY cell line, only 8c, 8f, 12c, and 24d maintained their viability inhibitory activities. The viability assay against non-neoplastic human fibroblast HFF1 cells suggested that compounds 8a, 8c, 8f, and 12c act selectively towards the panel of paediatric brain tumour cells. In contrast, compound 24d and WIN55,212-2 were highly toxic toward HFF1 cells. Due to their structural resemblance to known cannabimimetics, the most potent compounds were tested in cannabinoid 1 and 2 receptor (CB(1)R and CB(2)R) functional assays. Compounds 8a, 8c, and 12c failed to activate or antagonise both CB(1)R and CB(2)R, whereas compounds 8f and 24d antagonised CB(1)R and CB(2)R, respectively. We also performed a transcriptional analysis on KNS42 cells treated with our prototype compound 8a and highlighted a set of seven genes that were significantly downregulated. The expression levels of these genes were previously shown to be positively correlated with tumour growth and progression, indicating their implication in the antitumour activity of 8a. Overall, the drug-like and selective antitumour profiles of indole-2-carboxamides 8a, 8c, 8f, and 12c substantiate the versatility of the indole scaffold in cancer drug discovery.

// Simone Treiger Sredni 1, 2, 3 , Anders W. Bailey 1, 3, * , Amreena Suri 1, 3, * , Rintaro Hashizume 4 , Xingyao He 4 , Nundia Louis 4 , Tufan Gokirmak 5 , David R. Piper 5 , Daniel M. Watterson 6 and Tadanori Tomita 1, 2 1 Ann and Robert H. Lurie Children’s Hospital of Chicago, Division of Pediatric Neurosurgery, Chicago, IL 60611, USA 2 Northwestern University, Feinberg School of Medicine, Department of Surgery, Chicago, IL 60611, USA 3 Stanley Manne Children’s Research Institute, Cancer Biology and Epigenomics, Chicago, IL 60614, USA 4 Northwestern University, Feinberg School of Medicine, Department of Neurological Surgery, Chicago, IL 60611, USA 5 Thermo Fisher Scientific, Research and Development, Biosciences Division, Carlsbad, CA 92008, USA 6 Northwestern University, Feinberg School of Medicine, Department of Pharmacology, Chicago, IL 60611, USA * These authors have contributed equally to this work Correspondence to: Simone Treiger Sredni, email: ssredni@luriechildrens.org Keywords: embryonal tumors; CNS; AT/RT; RTK; polyploidy Received: October 10, 2017 Accepted: November 05, 2017 Published: November 24, 2017 ABSTRACT Rhabdoid tumors (RT) are highly aggressive and vastly unresponsive embryonal tumors. They are the most common malignant CNS tumors in infants below 6 months of age. Medulloblastomas (MB) are embryonal tumors that arise in the cerebellum and are the most frequent pediatric malignant brain tumors. Despite the advances in recent years, especially for the most favorable molecular subtypes of MB, the prognosis of patients with embryonal tumors remains modest with treatment related toxicity dreadfully high. Therefore, new targeted therapies are needed. The polo-like kinase 4 (PLK4) is a critical regulator of centriole duplication and consequently, mitotic progression. We previously established that PLK4 is overexpressed in RT and MB. We also demonstrated that inhibiting PLK4 with a small molecule inhibitor resulted in impairment of proliferation, survival, migration and invasion of RT cells. Here, we showed in MB the same effects that we previously described for RT. We also demonstrated that PLK4 inhibition induced apoptosis, senescence and polyploidy in RT and MB cells, thereby increasing the susceptibility of cancer cells to DNA-damaging agents. In order to test the hypothesis that PLK4 is a CNS druggable target, we demonstrated efficacy with oral administration to an orthotropic xenograft model. Based on these results, we postulate that targeting PLK4 with small-molecule inhibitors could be a novel strategy for the treatment of RT and MB and that PLK4 inhibitors (PLK4i) might be promising agents to be used solo or in combination with cytotoxic agents.

Polo-like kinase 4 (PLK4) is a cell cycle-regulated protein kinase (PK) recruited at the centrosome in dividing cells. Its overexpression triggers centrosome amplification, which is associated with genetic instability and carcinogenesis. In previous work, we established that PLK4 is overexpressed in pediatric embryonal brain tumors (EBT). We also demonstrated that PLK4 inhibition exerted a cytostatic effect in EBT cells. Here, we examined an array of PK inhibitors (CFI-400945, CFI-400437, centrinone, centrinone-B, R-1530, axitinib, KW-2449, and alisertib) for their potential crossover to PLK4 by comparative structural docking and activity inhibition in multiple established embryonal tumor cell lines (MON, BT-12, BT-16, DAOY, D283). Our analyses demonstrated that: (1) CFI-400437 had the greatest impact overall, but similar to CFI-400945, it is not optimal for brain exposure. Also, their phenotypic anti-cancer impact may, in part, be a consequence of the inhibition of Aurora kinases (AURKs). (2) Centrinone and centrinone B are the most selective PLK4 inhibitors but they are the least likely to penetrate the brain. (3) KW-2449, R-1530 and axitinib are the ones predicted to have moderate-to-good brain penetration. In conclusion, a new selective PLK4 inhibitor with favorable physiochemical properties for optimal brain exposure can be beneficial for the treatment of EBT.

BACKGROUND: In previous work we established that PLK4 is overexpressed and essential for proliferation and survival of pediatric embryonal brain tumors. PLK4 is a cell cycle-regulated protein recruited at the centrosome in dividing cells. Its overexpression triggers centrosome amplification, which is associated with genetic instability and carcinogenesis. We demonstrated that PLK4 inhibition exerts a potent cytostatic effect in EBT. We also established the synergism of the PLK4 inhibitor CFI-400945 with cytotoxic drugs and other signal transduction modulators. METHODS: We studied protein kinase inhibitors (PKI) with PLK4 cross-over potential (CFI-400945, CFI-400437, centrinone, centrinone-B, R-1530, axitinib, alisertib and KW-2449) by assessing their chemical profiles through docking simulations over PLK4 (PDB entry: 3COK) using Gold 5.4 software; evaluating their potential to penetrate the BBB (via logBB calculation by Clark equation), performing LanthaScreen EU Kinase Binding assays (ThermoFisher Scientific) and cell based studies (viability and proliferation) in multiple embryonal tumor cell lines (MON, BT-12, BT-16, DAOY, D283). RESULTS: Kinase binding assays and cell based studies showed that CFI-400437 was the most effective compound, yielding an IC(50)

Neuroblastoma (NB) is the most common extracranial solid tumor in pediatrics, with rare occurrences of primary and metastatic tumors in the central nervous system (CNS). We previously reported the overexpression of the polo-like kinase 4 (PLK4) in embryonal brain tumors. PLK4 has also been found to be overexpressed in a variety of peripheral adult tumors and recently in peripheral NB. Here, we investigated PLK4 expression in NBs of the CNS (CNS-NB) and validated our findings by performing a multi-platform transcriptomic meta-analysis using publicly available data. We evaluated the PLK4 expression by quantitative real-time PCR (qRT-PCR) on the CNS-NB samples and compared the relative expression levels among other embryonal and non-embryonal brain tumors. The relative PLK4 expression levels of the NB samples were found to be significantly higher than the non-embryonal brain tumors (p-value < 0.0001 in both our samples and in public databases). Here, we expand upon our previous work that detected PLK4 overexpression in pediatric embryonal tumors to include CNS-NB. As we previously reported, inhibiting PLK4 in embryonal tumors led to decreased tumor cell proliferation, survival, invasion and migration in vitro and tumor growth in vivo, and therefore PLK4 may be a potential new therapeutic approach to CNS-NB.

BACKGROUND: Previously, we observed that CRISPR/Cas9-induced mutations in the PLK4 gene, a critical regulator of centriole duplication, significantly impaired proliferation and survival of AT/RT cells. We established that PLK4 is overexpressed in AT/RT and inhibiting PLK4 resulted in impaired proliferation, survival, migration and invasion. It also induced polyploidy increasing AT/RT susceptibility to DNA-damaging drugs. The inhibition of AURKA, also overexpressed in AT/RT by alisertib, is currently in phase II clinical trial for the treatment of rhabdoid tumors (RT) (NCT02114229). We hypothesized that associating alisertib with a PLK4 inhibitor (PLK4i) would improve the efficacy of each drug. METHODS: We tested association of alisertib with the PLK4i CFI-400945 in three RT cell lines (MON, BT-12 and BT-16). Multiple concentrations for each inhibitor alone and in combination were tested. PrestoBlue viability and MTT proliferation assays were performed. RESULTS: Median effect plots showed that CFI-400945 associated with alisertib significantly decreased the concentration of both inhibitors needed to affect proliferation and viability in all cell lines tested. While alisertib alone required 200-500nM and CFI-400945 alone required 3.000–6.000nM to inhibit 50% proliferation and viability (IC50), combination of the two drugs required only 10-40nM of alisertib (13–20 times less) and 5-10nM of CFI-400945 (over 500 times less) to produce the same effect (p-value

The Plasmodium falciparum and P. berghei genomes each contain three dipeptidyl aminopeptidase ( dpap ) homologs. dpap1 and -3 are critical for asexual growth, but the role of dpap2 , the gametocyte-specific homolog, has not been tested. If DPAPs are essential for transmission as well as asexual growth, then a DPAP inhibitor could be used for treatment and to block transmission. To directly analyze the role of DPAP2, a dpap2 -minus P. berghei ( Pbdpap2 Δ) line was generated. The Pbdpap2 Δ parasites grew normally, differentiated into gametocytes, and generated sporozoites that were infectious to mice when fed to a mosquito. However, Pbdpap1 transcription was >2-fold upregulated in the Pbdpap2 Δ clonal lines, possibly compensating for the loss of Pbdpap2 . The role of DPAP1 and -3 in the dpap2 Δ parasites was then evaluated using a DPAP inhibitor, ML4118S. When ML4118S was added to the Pbdpap2 Δ parasites just before a mosquito membrane feed, mosquito infectivity was not affected. To assess longer exposures to ML4118S and further evaluate the role of DPAPs during gametocyte development in a parasite that causes human malaria, the dpap2 deletion was repeated in P. falciparum . Viable P. falciparum dpap2 ( Pfdpap2 )-minus parasites were obtained that produced morphologically normal gametocytes. Both wild-type and Pfdpap2 -negative parasites were sensitive to ML4118S, indicating that, unlike many antimalarials, ML4118S has activity against parasites at both the asexual and sexual stages and that DPAP1 and -3 may be targets for a dual-stage drug that can treat patients and block malaria transmission.

Malaria transmission requires the production of male and female gametocytes in the human host followed by fertilization and sporogonic development in the mosquito midgut. Although essential for the spread of malaria through the population, little is known about the initiation of gametocytogenesis in vitro or in vivo. Using a gametocyte-defective parasite line and genetic complementation, we show that Plasmodium falciparum gametocyte development 1 gene (Pfgdv1), encoding a peri-nuclear protein, is critical for early sexual differentiation. Transcriptional analysis of Pfgdv1 negative and positive parasite lines identified a set of gametocytogenesis early genes (Pfge) that were significantly down-regulated (>10 fold) in the absence of Pfgdv1 and expression was restored after Pfgdv1 complementation. Progressive accumulation of Pfge transcripts during successive rounds of asexual replication in synchronized cultures suggests that gametocytes are induced continuously during asexual growth. Comparison of Pfge gene transcriptional profiles in patient samples divided the genes into two groups differing in their expression in mature circulating gametocytes and providing candidates to evaluate gametocyte induction and maturation separately in vivo. The expression profile of one of the early gametocyte specific genes, Pfge1, correlated significantly with asexual parasitemia, which is consistent with the ongoing induction of gametocytogenesis during asexual growth observed in vitro and reinforces the need for sustained transmission-blocking strategies to eliminate malaria., Author Summary As malaria control efforts move toward eradication it becomes increasingly important to develop interventions that block transmission. Consequently, advances are needed in our understanding of the production of gametocytes, which are required to transmit the disease. This report provides a first view of the initial stages of gametocytogenesis in vitro and in vivo and demonstrates that during each asexual replication cycle a subpopulation of parasites convert to gametocyte development providing a long transmission window. We also identify a gene that is critical for gametocyte production, P. falciparum gametocyte development 1 (Pfgdv1) and a set of genes specifically expressed during early gametocytogenesis in P. falciparum (Pfge genes). The expression profile and peri-nuclear location of Pfgdv1 in a subpopulation of schizonts is consistent with a role in an early step in gametocytogenesis. The RNA levels of Pfgdv1 and the Pfge genes accumulated gradually over several asexual cycles in vitro suggesting ongoing gametocyte formation during asexual growth. The further evaluation of these genes in a cohort of malaria infected patients indicated they are good candidates for markers to distinguish ring stage parasites committed to gametocyte production from circulating mature gametocytes, allowing direct analysis of the initiation of sexual differentiation in vivo.