Pooled Generation of Lentiviral Tetracycline-Regulated microRNA Embedded Short Hairpin RNA Libraries

Gene regulatory network analysis predicts cooperating transcription factor regulons required for FLT3-ITD+ AML growth

Acute myeloid leukemia (AML) is a heterogeneous disease caused by different mutations. Previously, we showed that each mutational subtype develops its specific gene regulatory network (GRN) with transcription factors interacting within multiple gene modules, many of which are transcription factor genes themselves. Here, we hypothesize that highly connected nodes within such networks comprise crucial regulators of AML maintenance. We test this hypothesis using FLT3-ITD-mutated AML as a model and conduct an shRNA drop-out screen informed by this analysis. We show that AML-specific GRNs predict crucial regulatory modules required for AML growth. Furthermore, our work shows that all modules are highly connected and regulate each other. The careful multi-omic analysis of the role of one (RUNX1) module by shRNA and chemical inhibition shows that this transcription factor and its target genes stabilize the GRN of FLT3-ITD+ AML and that its removal leads to GRN collapse and cell death.

Assessment and streamlined preparation of low-cytotoxicity lentiviral vectors for mobilized human hematopoietic stem cell transduction

As important vectors for ectopic protein expression, gene silencing, and progenitor cell barcoding, lentiviruses continue to emerge as versatile research and clinical tools. For studies employing cell types that are relatively resistant to transduction, high-titer lentivirus preparations with low cytotoxicity are required. During lentivirus production, carryover plasmid DNA endotoxins, transfection reagents, damaged packaging cells, and virus concentration procedures are potential sources of cytotoxicity. As an often unevaluated property of lentivirus preparations, cytotoxicity can unwittingly skew estimates of functional titers and complicate interpretations of transduced cell phenotypes. By employing hematopoietic UT7epo cells cultured in erythropoietin (EPO) below maximal dosing, we first define a sensitive flow cytometric bioassay for critically assessing the cytotoxicity (and titers) of lentivirus preparations. Bioassay of custom preparations of research-grade lentiviruses from six commercial sources unexpectedly revealed substantial cytotoxicity (with certain preparations additionally registering titers several log below designated values). To overcome such limiting properties, we further report on unique, efficient workflows for reproducibly preparing and processing high-titer, low-cytotoxicity (HTLC) lentiviruses at research scale. These HTLC lentiviruses reliably transduce peripheral blood hematopoietic stem/progenitor cells (PB-HSPCs) at frequencies ≥40%, with low cytotoxicity. In addition, by employing cyclosporin H (to inhibit IFITM3), PB-HSPCs can be transduced at heightened efficiency with nominal cytotoxicity. Overall, this work provides straightforward approaches to (1) critical assessment of the cytotoxicity of lentivirus preparations; (2) reproducible generation (and concentration) of high-quality lentiviruses via a streamlined workflow; and (3) transduction of PB-HSPCs at benchmark levels with nominal cytotoxicity.

Expression of miR-204 in pediatric retinoblastoma and its effects on proliferation and apoptosis of cancer cells

Expression, clinical significance and molecular mechanism of miR-204 in human retinoblastoma (RB) and para-carcinoma tissues were investigated. A total of 110 cases of RB tissues preserved after ophthalmectomy in the First Affiliated Hospital of Hunan Normal University (People's Hospital of Hunan Province) from April 2013 to June 2017 were collected along with 100 cases of para-carcinoma normal tissues. The expression of miR-204 in RB tissues was detected via reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and its associations with clinicopathological features were analyzed. Y79 cells were transfected with miR-204 mimics. A total of 80 pmol/l miR-204 mimics and 10 µl Lipofectamine 2000 were added into the experimental group. Cell proliferation was detected via methyl thiazolyl tetrazolium (MTT) assay at 24, 48, 72 and 96 h, apoptosis was detected via flow cytometry at 48 h after transfection, and the relative expression levels of B-cell lymphoma 2 (Bcl-2) messenger RNA (mRNA) and Sirt1 mRNA were detected via RT-qPCR. The results of MTT assay revealed that the measured value of the optical density (OD) in the experimental group at 48 h was obviously lower than that in the negative control group (p<0.001). The proportion of apoptotic cells in the experimental group was remarkably higher than that in the negative control group (p<0.001). Compared with those in the negative control group, the relative expression levels of Bcl-2 and Sirt1 mRNAs in the experimental group were significantly decreased (p<0.001). miR-204 may be involved in the occurrence and development of RB, which is significantly associated with clinical tissue differentiation, neural infiltration and lymph node metastasis in patients. miR-204 may inhibit proliferation and promote apoptosis of RB cells through downregulating the expression of Bcl-2 and Sirt1 in RB. Therefore, miR-204 may become a new biological index for early diagnosis, prognosis evaluation and biotherapy of RB.