The molecular etiology of human progenitor reprogramming into self-renewing leukemia stem cells (LSC) has remained elusive. Although DNA sequencing has uncovered spliceosome gene mutations that promote alternative splicing and portend leukemic transformation, isoform diversity also may be generated by RNA editing mediated by adenosine deaminase acting on RNA (ADAR) enzymes that regulate stem cell maintenance. In this study, wholetranscriptome sequencing of normal, chronic phase, and serially transplantable blast crisis chronic myeloid leukemia (CML) progenitors revealed increased IFN-γ pathway gene expression in concert with BCR-ABL amplification, enhanced expression of the IFN-responsive ADAR1 p150 isoform, and a propensity for increased adenosine-to-inosine RNA editing during CML progression. Lentiviral overexpression experiments demonstrate that ADAR1 p150 promotes expression of the myeloid transcription factor PU.1 and induces malignant reprogramming of myeloid progenitors. Moreover, enforced ADAR1 p150 expression was associated with production of a misspliced form of GSK3β implicated in LSC self-renewal. Finally, functional serial transplantation and shRNA studies demonstrate that ADAR1 knockdown impaired in vivo self-renewal capacity of blast crisis CML progenitors. Together these data provide a compelling rationale for developing ADAR1-based LSC detection and eradication strategies.

SUMMARY Post-transcriptional adenosine-to-inosine RNA editing mediated by adenosine deaminase acting on RNA1 (ADAR1) promotes cancer progression and therapeutic resistance. However, ADAR1 editase-dependent mechanisms governing leukemia stem cell (LSC) generation have not been elucidated. In blast crisis chronic myeloid leukemia (BC CML), we show that increased JAK2 signaling and BCR-ABL1 amplification activate ADAR1. In a humanized BC CML mouse model, combined JAK2 and BCR-ABL1 inhibition prevents LSC self-renewal commensurate with ADAR1 downregulation. Lentiviral ADAR1 wild-type, but not an editing-defective ADAR1E912 mutant, induces self-renewal gene expression and impairs biogenesis of stem cell regulatory let-7 microRNAs. Combined RNA sequencing, qRT-PCR, CLIP-ADAR1, and pri-let-7 mutagenesis data suggest that ADAR1 promotes LSC generation via let-7 pri-microRNA editing and LIN28B upregulation. A small molecule tool compound antagonizes ADAR1’s effect on LSC self-renewal in stromal co-cultures and restores let-7 biogenesis. Thus, ADAR1 activation represents a unique therapeutic vulnerability in LSC with active JAK2 signaling.

BACKGROUND-Bacterial vaginosis affects 15 to 50% of women of reproductive age, and recurrence is common after treatment with an antibiotic agent. The high incidence of recurrence suggests the need for new treatments to prevent recurrent bacterial vaginosis. METHODS-We conducted a randomized, double-blind, placebo-controlled, phase 2b trial to evaluate the ability of Lactobacillus crispatus CTV-05 (Lactin-V) to prevent the recurrence of bacterial vaginosis. Women 18 to 45 years of age who had received a diagnosis of bacterial vaginosis and who had completed a course of vaginal metronidazole gel as part of the eligibility requirements were randomly assigned, in a 2:1 ratio, to receive vaginally administered Lactin-V or placebo for 11 weeks; follow-up occurred through week 24. The primary outcome was the percentage of women who had a recurrence of bacterial vaginosis by week 12. RESULTS-A total of 228 women underwent randomization: 152 to the Lactin-V group and 76 to the placebo group; of these participants, 88% in the Lactin-V group and 84% in the placebo group could be evaluated for the primary outcome. In the intention-to-treat population, recurrence of bacterial vaginosis by week 12 occurred in 46 participants (30%) in the Lactin-V group and in 34 participants (45%) in the placebo group (risk ratio after multiple imputation for missing responses, 0.66; 95% confidence interval [CI], 0.44 to 0.87; P = 0.01). The risk ratio for recurrence by week 24 (also calculated with multiple imputation for missing responses) was 0.73 (95% CI, 0.54 to 0.92). At the 12-week visit, L. crispatus CTV-05 was detected in 79% of participants in the Lactin-V group.

Summary Leukemia stem cells (LSC) play a pivotal role in chronic myeloid leukemia (CML) tyrosine kinase inhibitor (TKI) resistance and progression to blast crisis (BC), in part, through alternative splicing of self-renewal and survival genes. To elucidate splice isoform regulators of human BC LSC maintenance, we performed whole transcriptome RNA sequencing; splice isoform-specific qRT-PCR, nanoproteomics, stromal co-culture and BC LSC xenotransplantation analyses. Cumulatively, these studies show that alternative splicing of multiple pro-survival BCL2 family genes promotes malignant transformation of myeloid progenitors into BC LSC that are quiescent in the marrow niche and contribute to therapeutic resistance. Notably, a novel pan-BCL2 inhibitor, sabutoclax, renders marrow niche-resident BC LSC sensitive to TKIs at doses that spare normal progenitors. These findings underscore the importance of alternative BCL2 family splice isoform expression in BC LSC maintenance and suggest that combinatorial inhibition of pro-survival BCL2 family proteins and BCR-ABL may eliminate dormant LSC and obviate resistance.

SUMMARY Age-related human hematopoietic stem cell (HSC) exhaustion and myeloid-lineage skewing promote oncogenic transformation of hematopoietic progenitor cells into therapy-resistant leukemia stem cells (LSC) in secondary acute myeloid leukemia (sAML). While acquisition of clonal DNA mutations have been linked to increased rates of sAML for individuals over 60, the contribution of RNA processing alterations to human hematopoietic stem and progenitor aging and LSC generation remains unclear. Comprehensive RNA-sequencing and splice isoform-specific PCR uncovered characteristic RNA splice isoform expression patterns that distinguished normal young and aged HSPCs, compared with malignant MDS and AML progenitors. In splicing reporter assays and in pre-clinical patient-derived AML models, treatment with a pharmacologic splicing modulator, 17S-FD-895, reversed pro-survival splice isoform switching and significantly impaired LSC maintenance. By comparing splice isoform biomarkers of normal HSPC aging with those of LSC generation, splicing modulation may be employed safely and effectively to prevent relapse – the leading cause of leukemia-related mortality.

NCT01761643.

The pharynx is a common, asymptomatic reservoir for gonorrhea in sexually active MSM.

Background It remains unclear if methamphetamine is merely associated with high risk behavior or if methamphetamine use causes high risk behavior. Determining this would require a randomized controlled trial, which is clearly not ethical. A possible surrogate would be to investigate individuals before and after starting the use of methamphetamine. Methods We performed a cohort study to analyze recent self-reported methamphetamine use and sexual risk behavior among 8,905 MSM receiving the “Early Test”, a community-based, HIV screening program in San Diego, California, between April 2008 and July 2014 (total 17,272 testing encounters). Sexual risk behavior was evaluated using a previously published risk behavior score (San Diego Early Test [SDET] score) that predicts risk of HIV acquisition. Results Methamphetamine use during the last 12 months (hereafter, recent-meth) was reported by 754/8,905 unique MSM (8.5%). SDET scores were significantly higher in the 754 MSM with recent-meth use compared to the 5,922MSM who reported that they have never used methamphetamine (p<0.001). Eighty-two repeat testers initiated methamphetamine between testing encounter, with significantly higher SDET scores after starting methamphetamine (median 5 [IQR 2–7] at recent-meth versus median 3 [IQR 0–5] at never-meth; p<0.001, respectively). Conclusions Given the ethical impossibility of conducting a randomized, controlled trial, the results presented here provide the strongest evidence yet that initiation of methamphetamine use increases sexual risk behavior among HIV-uninfected MSM. Until more effective prevention or treatment interventions are available for methamphetamine users, HIV-uninfected MSM who use methamphetamine may represent ideal candidates for alternative effective prevention interventions (i.e., pre-exposure prophylaxis).