A novel network pharmacology approach for leukaemia differentiation therapy using Mogrify®.

Acute myeloid leukaemia (AML) is a rapidly fatal blood cancer that is characterised by the accumulation of immature myeloid cells in the blood and bone marrow as a result of blocked differentiation. Methods which identify master transcriptional regulators of AML subtype-specific leukaemia cell states and their combinations could be critical for discovering novel differentiation-inducing therapies. In this proof-of-concept study, we demonstrate a novel utility of the Mogrify® algorithm in identifying combinations of transcription factors (TFs) and drugs, which recapitulate granulocytic differentiation of the NB4 acute promyelocytic leukaemia (APL) cell line, using two different approaches. In the first approach, Connectivity Map (CMAP) analysis of these TFs and their target networks outperformed standard approaches, retrieving ATRA as the top hit. We identify dimaprit and mebendazole as a drug combination which induces myeloid differentiation. In the second approach, we show that genetic manipulation of specific Mogrify®-identified TFs (MYC and IRF1) leads to co-operative induction of APL differentiation, as does pharmacological targeting of these TFs using currently available compounds. We also show that loss of IRF1 blunts ATRA-mediated differentiation, and that MYC represses IRF1 expression through recruitment of PML-RARα, the driver fusion oncoprotein in APL, to the IRF1 promoter. Finally, we demonstrate that these drug combinations can also induce differentiation of primary patient-derived APL cells, and highlight the potential of targeting MYC and IRF1 in high-risk APL. Thus, these results suggest that Mogrify® could be used for drug discovery or repositioning in leukaemia differentiation therapy for other subtypes of leukaemia or cancers.

Multiple joint effusions associated with high-dose imatinib therapy in a patient with chronic myelogenous leukaemia.

Imatinib mesylate is a small molecule tyrosine kinase inhibitor that has significant efficacy in the treatment of chronic myelogenous leukaemia (CML). However, it is likely that patients with CML will require prolonged and perhaps life-long therapy. In general, the side-effects of imatinib therapy have been mild to moderate, with the large majority of patients tolerating prolonged periods of therapy. However, a minority of patients are completely intolerant of therapy, while others are able to remain on therapy despite significant side-effects. Here, we describe a novel form of fluid retention presenting as multiple joint effusions in a patient with advanced phase CML on high-dose imatinib, as well as successful measures that were undertaken to control this adverse event. Although fluid retention, including periorbital oedema, pleural and pericardial effusions, as well as life-threatening cerebral oedema have been previously described and attributed to imatinib, this is the first case of imatinib-associated polyarticular effusions that we are aware of. Further work will be required to confirm a casual relationship between imatinib therapy and this novel side-effect, as well as to determine the underlying pathophysiologic mechanisms.

Expression profiling of a transformed thymocyte cell line undergoing maturation in vitro identifies multiple genes involved in positive selection.

Biochemical and genetic studies of thymocyte maturation would be facilitated by the development of cultured cell lines that reflect stages of positive selection. We have derived a CD4(+)CD8(+)TCR(+) T-lymphoid cell line (M20) from a murine thymic tumor induced by a retrovirus carrying the v-myc oncogene (M-MuLV(myc)). M20 subclones undergo several aspects of positive selection in response to co-culture with a thymic stromal cell line (St3), including down-regulation of CD4 and CD8, and up-regulation of CD5 and TCR. M20 possesses a functional TCR complex, and ligation of this complex produces changes similar to co-culture with St3 stroma. Expression profiling of M20 cells in this system identified 23 genes previously shown to be important in thymocyte maturation, as well as several novel candidate genes. This system provides a new model to elucidate the molecular mechanisms of thymocyte maturation and TCR-mediated cell signaling in double-positive thymocytes.