Targeting BET Proteins Downregulates miR-33a To Promote Synergy with PIM Inhibitors in CMML

PURPOSE

Preclinical studies in myeloid neoplasms have demonstrated efficacy of bromodomain and extra-terminal protein inhibitors (BETi). However, BETi demonstrates poor single-agent activity in clinical trials. Several studies suggest that combination with other anticancer inhibitors may enhance the efficacy of BETi.

EXPERIMENTAL DESIGN

To nominate BETi combination therapies for myeloid neoplasms, we used a chemical screen with therapies currently in clinical cancer development and validated this screen using a panel of myeloid cell line, heterotopic cell line models, and patient-derived xenograft models of disease. We used standard protein and RNA assays to determine the mechanism responsible for synergy in our disease models.

RESULTS

We identified PIM inhibitors (PIMi) as therapeutically synergistic with BETi in myeloid leukemia models. Mechanistically, we show that PIM kinase is increased after BETi treatment, and that PIM kinase upregulation is sufficient to induce persistence to BETi and sensitize cells to PIMi. Furthermore, we demonstrate that miR-33a downregulation is the underlying mechanism driving PIM1 upregulation. We also show that GM-CSF hypersensitivity, a hallmark of chronic myelomonocytic leukemia (CMML), represents a molecular signature for sensitivity to combination therapy.

CONCLUSIONS

Inhibition of PIM kinases is a potential novel strategy for overcoming BETi persistence in myeloid neoplasms. Our data support further clinical investigation of this combination.

The Various Scoring Systems in Pediatric Intensive Care Units: A Prospective Observational Study

BACKGROUND

The discrimination power of the pediatric risk of mortality (PRISM), pediatric index of mortality (PIM), sequential organ failure assessment (SOFA), and pediatric logistic organ dysfunction (PELOD) may not always be true for countries such as India due to differences in factors from those nations where these scoring systems were validated. Therefore, this study was undertaken to determine and compare severity, course of illness, and outcomes in critically ill children admitted to the pediatric intensive care unit (PICU) using different scoring systems such as PRISM 4, PIM 3, PELOD 2, and the pediatric sequential organ failure assessment (pSOFA ) score, and to analyze the clinical spectrum and demographic profile of children admitted to the PICU.

MATERIALS AND METHOD

This was a prospective, single-center, observational study conducted in the PICU of the Indira Gandhi Institute of Medical Science, Patna, India, over two years. Two hundred children in the age group of one month to 14 years admitted to the PICU were recruited into the study. Prognostic scoring systems, including PRISM4 and PIM3, were used to compare the outcome, mortality, and length of PICU stay, whereas PELODS and pSOFA were descriptive scores that assessed the multiorgan dysfunction. A correlation between the different scoring systems and the outcome was determined.

RESULTS

The majority of children (26.5%, n=53) were one to three years of age. The maximum number of patients was male (66.5%, n=133). Renal complications were the predominant admission diagnosis in 19% (n=38) of children. The mortality rate was found to be 18.5%. The mortality was most common in infants <1 year of age (n=11, 29.73%) and those of the male sex (n=22, 59.46%). A significant correlation was found between length of stay and mortality (p<0.00001). A significant positive correlation was observed between mortality and PRISM 4, PIM 3, PELOD 2, and pSOFA scores on the first day of admission (p<0.00001). The pSOFA and PELOD2 showed better discrimination power (area under the curve (AUC): 0.77 and 0.74, respectively).

CONCLUSION

The study concluded that the pSOFA and PELOD2 scores are reliable predictors of mortality in critically ill children.

Virus-induced gene silencing of PEAM4 affects floral morphology by altering the expression pattern of PsSOC1a and PsPVP in pea

pea-MADS4 (PEAM4) regulates floral morphology in Pisum sativum L., however, its molecular mechanisms still remain unclear. Virus-induced gene silencing (VIGS) is a recently developed reverse genetic approach that facilities an easier and more rapid study of gene functions. In this study, the PEAM4 gene was effectively silenced by VIGS using a pea early browning virus (PEBV) in wild type pea JI992. The infected plants showed abnormal phenotypes, as the floral organs, especially the sepals and petals changed in both size and shape, which made the corolla less closed. The petals changed in morphology and internal symmetry with, the stamens reduced and carpel dehisced. Larger sepals and longer tendrils with small cauline leaves appeared, with some sepals turning into bracts, and secondary inflorescences with fused floral organs were formed, indicating a flower-to-inflorescence change. The infected plants also displayed a delayed and prolonged flowering time. The PEAM4-VIGS plants with altered floral morphology were similar to the pim (proliferating inflorescence meristem) mutant and also mimicked the phenotypes of ap1 mutants in Arabidopsis. The expression pattern of the homologous genes PsSOC1a and PsSVP, which were involved in flowering time and florescence morphological control downstream of PEAM4, were analyzed by real-time RT-PCR and mRNA in situ hybridization. PsSOC1a and PsSVP were ectopically expressed and enhanced in the floral meristems from PEAM4-silenced plants. Our data suggests that PEAM4 may have a similar molecular mechanism as AtAP1, which inhibits the expression of PsSOC1a and PsSVP in the floral meristem from the early stages of flower development. As such, in this way PEAM4 plays a crucial role in maintaining floral organ identity and flower development in pea.

Crystallization and preliminary crystallographic analysis of PimA, an essential mannosyltransferase from Mycobacterium smegmatis

Phosphatidylinositol mannosyltransferase (PimA) is an essential enzyme for mycobacterial growth that catalyses the first mannosylation step in phosphatidyl-myo-inositol mannoside (PIM) biosynthesis. The enzyme belongs to the large GT4 family of glycosyltransferases, for which no structure is currently available. Recombinant purified PimA from Mycobacterium smegmatis has been crystallized in the presence of GDP and myo-inositol. The crystals belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 37.2, b = 72.4, c = 138.2 A, and diffract to 2.4 A resolution.