Synthetic Lethal Screen Identifies NF-κB as a Target for Combination Therapy with Topotecan for patients with Neuroblastoma

<p>Abstract</p> <p>Background</p> <p>Despite aggressive multimodal treatments the overall survival of patients with high-risk neuroblastoma remains poor. The aim of this study was to identify novel combination chemotherapy to improve survival rate in patients with high-risk neuroblastoma.</p> <p>Methods</p> <p>We took a synthetic lethal approach using a siRNA library targeting 418 apoptosis-related genes and identified genes and pathways whose inhibition synergized with topotecan. Microarray analyses of cells treated with topotecan were performed to identify if the same genes or pathways were altered by the drug. An inhibitor of this pathway was used in combination with topotecan to confirm synergism by <it>in vitro </it>and <it>in vivo </it>studies.</p> <p>Results</p> <p>We found that there were nine genes whose suppression synergized with topotecan to enhance cell death, and the NF-κB signaling pathway was significantly enriched. Microarray analysis of cells treated with topotecan revealed a significant enrichment of NF-κB target genes among the differentially altered genes, suggesting that NF-κB pathway was activated in the treated cells. Combination of topotecan and known NF-κB inhibitors (NSC 676914 or bortezomib) significantly reduced cell growth and induced caspase 3 activity <it>in vitro</it>. Furthermore, in a neuroblastoma xenograft mouse model, combined treatment of topotecan and bortezomib significantly delayed tumor formation compared to single-drug treatments.</p> <p>Conclusions</p> <p>Synthetic lethal screening provides a rational approach for selecting drugs for use in combination therapy and warrants clinical evaluation of the efficacy of the combination of topotecan and bortezomib or other NF-κB inhibitors in patients with high risk neuroblastoma.</p

The development and validation of a scoring tool to predict the operative duration of elective laparoscopic cholecystectomy.

Peer reviewe

Relatório de estágio em farmácia comunitária

Relatório de estágio realizado no âmbito do Mestrado Integrado em Ciências Farmacêuticas, apresentado à Faculdade de Farmácia da Universidade de Coimbr

Anti-tumor immunity in a model of acute myeloid leukemia

Whole-cell vaccines allow the induction of anti-tumor immune responses without the need to define tumor antigens. We wished to directly compare, for the first time, the capacity of B7-1, B7-2 and 4-1BB ligand (4-1BBL) costimulatory molecules to convert murine and human acute myeloid leukemia (AML) cells into whole vaccines. 32Dc-kit is a murine myeloid cell line, which develops an AML-like disease over a protracted period, emulating human AML disease development. 32Dc-kit cells were modified to express elevated levels of B7-1, B7-2 or 4-1BBL, and each led to tumor rejection, although only mice injected with 32Dc-kit/B7-2 cells were able to reject subsequent parental tumor cell challenge. T-cell deficient nude mice were able to reject the 32Dc-kit variants, but they could not reject parental cell challenge; however, we found no evidence of cytotoxic T lymphocyte or natural killer (NK) activity ex vivo suggesting that tumor cell killing was mediated by an immune response that could not be recapitulated using purified NK or T cells as lone effectors. In human allogeneic mixed lymphocyte reactions (MLRs), we found no single costimulatory molecule was more effective, suggesting that the induction of a universal anti-tumor response will require a combination of costimulatory molecules

Targeting Wild-Type and Mutationally Activated FGFR4 in Rhabdomyosarcoma with the Inhibitor Ponatinib (AP24534)

<div><p>Rhabdomyosarcoma (RMS) is the most common childhood soft tissue sarcoma. Despite advances in modern therapy, patients with relapsed or metastatic disease have a very poor clinical prognosis. Fibroblast Growth Factor Receptor 4 (FGFR4) is a cell surface tyrosine kinase receptor that is involved in normal myogenesis and muscle regeneration, but not commonly expressed in differentiated muscle tissues. Amplification and mutational activation of FGFR4 has been reported in RMS and promotes tumor progression. Therefore, FGFR4 is a tractable therapeutic target for patients with RMS. In this study, we used a chimeric Ba/F3 TEL-FGFR4 construct to test five tyrosine kinase inhibitors reported to specifically inhibit FGFRs in the nanomolar range. We found ponatinib (AP24534) to be the most potent FGFR4 inhibitor with an IC₅₀ in the nanomolar range. Ponatinib inhibited the growth of RMS cells expressing wild-type or mutated FGFR4 through increased apoptosis. Phosphorylation of wild-type and mutated FGFR4 as well as its downstream target STAT3 was also suppressed by ponatinib. Finally, ponatinib treatment inhibited tumor growth in a RMS mouse model expressing mutated FGFR4. Therefore, our data suggests that ponatinib is a potentially effective therapeutic agent for RMS tumors that are driven by a dysregulated FGFR4 signaling pathway.</p></div

Ponatinib (AP24534) holds cell cycling at sub G₁ phase and induces cell death via apoptosis.

<p>(A) Cell cycle analysis of the two most sensitive cell lines to ponatinib, RH4 and RH5, and the two RMS772 cell lines expressing FGFR4 mutations (N535K and V550E) showed increased time in sub G₁ phase and decreased time in S phase across all four cell lines after 24 hours of treatment with 2.5 µM ponatinib. (B) Cell death induced by 2.5 µM ponatinib treatment is mediated <i>via</i> the caspase 3/7 pathway (*p = 0.0029, **p = 0.0027, ***p = 0.0017, ****p = 0.0001).</p

RMS772 cell harboring activating FGFR4 mutations V550E or N535K are more sensitive to ponatinib (AP24534) after 24 hour treatment than RMS772 cells expressing wild-type (WT) FGFR4 or the empty vector (VCtrl) (*p = <0.0001, **p = <0.0001).

<p>RMS772 cell harboring activating FGFR4 mutations V550E or N535K are more sensitive to ponatinib (AP24534) after 24 hour treatment than RMS772 cells expressing wild-type (WT) FGFR4 or the empty vector (VCtrl) (*p = <0.0001, **p = <0.0001).</p

RMS cell lines with overexpressed FGFR4 are more sensitive to ponatinib.

<p>(A) The sensitivity of a panel of six fusion-positive RMS cell lines (RH4, RH28, JR, RH41, RH5, and RH30) and eight fusion-negative RMS cell lines (BIRCH, RH18, TTC-442, CT-10, CTR, TTC-516, RD, and RH36) to ponatinib is correlated to FGFR4 mRNA expression levels by Spearman ranking (p = 0.0261). (B) Comparing the variation in IC₅₀ values of fusion-positive (FP) and fusion-negative (FN) RMS cell lines shows a significant difference by F test (p = 0.0125). (C) A difference in IC₅₀ values can be seen between RMS cell lines expressing low (below a relative level of 6) and high (above a relative level of 6) levels of FGFR4 (p = 0.0344).</p