Mixed-lineage leukemia protein modulates the loading of let-7a onto AGO1 by recruiting RAN.

Not available.

Tumor-intrinsic CD21 expression impacts the response of B-cell malignancy cells to CD19-CAR-T cells.

CD19-chimeric antigen receptor (CAR)-based T-cell therapy has produced promising clinical responses in patients with relapsed or refractory B-cell malignancies. However, a significant portion of patients with mature B cell-derived malignancies, including chronic lymphocytic leukemia (CLL) and non-Hodgkin's lymphoma (NHL), do not respond to CD19-CAR-T cell therapy. Whether any characteristics and biomarkers intrinsic to cancer cells themselves can predict the CD19-CAR-T cell therapeutic response remains largely unknown. Surprisingly, by using experimental models, we show here that malignant B cells bearing CD21, a mature B cell marker, could not be efficiently killed by CD19-CAR-T cells. CD19, CD21, and CD81, together with CD225, form the B cell coreceptor complex that enhances B cell-mediated signaling. Our results indicated that CD21 affected the recognition of CD19-positive tumor cells by CD19-CAR-T cells and impaired the antitumor capacities of these effector cells. We have not only uncovered a mechanism underlying the impairment of CD19-CAR-T cells in mature B cell-derived CLL and NHL, but also proposed a pretreatment biomarker that may predict CD19-CAR-T cell therapeutic response, thus preventing foreseeable therapy failure and suggesting optimal personized therapies.

Restoring MLL reactivates latent tumor suppression-mediated vulnerability to proteasome inhibitors.

MLL undergoes multiple distinct chromosomal translocations to yield aggressive leukemia with dismal outcomes. Besides their well-established role in leukemogenesis, MLL fusions also possess latent tumor-suppressive activity, which can be exploited as effective cancer treatment strategies using pharmacological means such as proteasome inhibitors (PIs). Here, using MLL-rearranged xenografts and MLL leukemic cells as models, we show that wild-type MLL is indispensable for the latent tumor-suppressive activity of MLL fusions. MLL dysfunction, shown as loss of the chromatin accumulation and subsequent degradation of MLL, compromises the latent tumor suppression of MLL-AF4 and is instrumental for the acquired PI resistance. Mechanistically, MLL dysfunction is caused by chronic PI treatment-induced epigenetic reprogramming through the H2Bub-ASH2L-MLL axis and can be specifically restored by histone deacetylase (HDAC) inhibitors, which induce histone acetylation and recruits MLL on chromatin to promote cell cycle gene expression. Our findings not only demonstrate the mechanism underlying the inevitable acquisition of PI resistance in MLL leukemic cells, but also illustrate that preventing the emergence of PI-resistant cells constitutes a novel rationale for combination therapy with PIs and HDAC inhibitors in MLL leukemias.

Protective effects of a new metalloporphyrin on paraquat-induced oxidative stress and apoptosis in N27 cells.

Paraquat (PQ, 1,1'-dimethyl-4,4'-bipyridinium), a widely-used herbicide, has been suggested as a potential etiologic factor for the development of Parkinson's disease. In recent years, many studies have focused on the mechanism(s) of PQ neurotoxicity. In this study, we examined the neuroprotective effect of manganese (III) meso-tetrakis (N,N'-diethylimidazolium) porphyrin (MnTDM), a superoxide dismutase/catalase mimetic, on PQ-induced oxidative stress and apoptosis in 1RB3AN27 (N27) cells, a dopaminergic neuronal cell line. The results indicated that MnTDM significantly attenuated PQ-induced loss of cell viability, glutathione depletion, and reactive oxygen species production. MnTDM also ameliorated PQ-induced morphological nuclear changes of apoptosis and increased rates of apoptosis. In addition, our data provide direct evidence that MnTDM suppressed PQ-induced caspase-3 cleavage, possibly a key event of PQ neurotoxicity. These observations suggested that oxidative stress and apoptosis are implicated in PQ-induced neurotoxicity and this toxicity could be prevented by MnTDM. These findings also proposed a novel therapeutic approach for Parkinson's disease and other disorders associated with oxidative stress.

Catalytic metalloporphyrin protects against paraquat neurotoxicity in vivo.

OBJECTIVE: To examine the neuroprotective effects of a novel manganese porphyrin, manganese (III) meso-tetrakis (N,N'-diethylimidazolium-2-yl) porphyrin (MnTDM), in the mouse model of Parkinson's disease (PD) induced by paraquat (PQ). METHODS: Male C57BL/6 mice were subcutaneously injected with either saline or PQ at 2-day intervals for a total of 10 doses, MnTDM was subcutaneously injected with the PQ 2 h before treatment. Performance on the pole and swim test were measured 7 days after the last injection and animals were sacrificed one day later. Levels of dopamine (DA) and its metabolites in the striatum were measured by high-performance liquid chromatography with an electrochemical detector (HPLC-ECD). Thiobarbituric acid (TBA) method was used to assay the lipid peroxidation product, malondialdehyde (MDA), and the number of tyrosine hydroxylase (TH) positive neurons was estimated using immunohistochemistry. RESULTS: Pretreatment with MnTDM significantly attenuated PQ-impaired behavioral performance, depleted dopamine content in striata, increased MDA, and dopaminergic neuron loss in the substantia nigra. CONCLUSIONS: Oxidative stress plays an important role in PQ-induced neurotoxicity which can be potentially prevented by manganese porphyrin. These findings also propose a possible therapeutical strategy for neurodegenerative disorders associated with oxidative stress such as PD.

A Pilot Study of Preoperative Single-Dose Ipilimumab and/or Cryoablation in Women with Early-Stage Breast Cancer with Comprehensive Immune Profiling.

PURPOSE: To assess the safety and tolerability of preoperative cryoablation-mediated tumor antigen presentation and/or ipilimumab-mediated immune modulation in women with operable breast cancer. EXPERIMENTAL DESIGN: In this pilot study, 19 women with breast cancer for whom mastectomy was planned were treated with preoperative tumor cryoablation (n = 7), single-dose ipilimumab at 10 mg/kg (n = 6), or both (n = 6). The primary outcome for this pilot study was safety/tolerability as defined as freedom from delays in pre-planned, curative-intent mastectomy. Exploratory studies of immune activation were performed on peripheral blood and tumor. RESULTS: Preoperative cryoablation and/or ipilimumab were safe and tolerable, with no delays in pre-planned surgery. Grade III toxicity was seen in 1 of 19 (unrelated rash after ipilimumab). Combination therapy was associated with sustained peripheral elevations in: Th1-type cytokines, activated (ICOS+) and proliferating (Ki67+) CD4+ and CD8+ T cells, and posttreatment proliferative T-effector cells relative to T-regulatory cells within tumor. CONCLUSIONS: Preoperative cryoablation and single-dose ipilimumab are safe alone or in combination with no surgical delays incurred. Potentially favorable intratumoral and systemic immunologic effects were observed with the combination, suggesting the possibility for induced and synergistic antitumor immunity with this strategy. Clin Cancer Res; 22(23); 5729-37. ©2016 AACR.

[Establishment of CPP-SOM integrated cDNA microarray technology].

OBJECTIVE: To get an insight into the molecular mechanisms of diseases development and targeted therapy at the transcriptome level and search for potential therapeutic targets. METHODS: The present researchers established a cDNA microarray platform and applied component plane presentation integrated self-organizing map (CPP-SOM) to the microarray data obtained from a differentiation model, all trans retinoic acid-induced differentiation in NB4 cells. RESULTS: The platform included 12630 unique clones, including 9436 known genes. By CPP-SOM, the researchers were able to not only well classify the regulated genes into functionally distinct categories but also depict transcriptional changes throughout the process of the development of diseases or drug treatment. CONCLUSION: The platform has proven to be steady and reliable, and the CPP-SOM could serve as an important and good tool for analysis of microarray data.

[Expression changes of genes related to calcium pathway in all-trans retinoic acid-induced differentiation of APL cells].

In order to investigate the role of calcium pathway in myeloid differentiation, the expression level of genes related to calcium pathway in all-trans retinoic acid (ATRA)-induced NB4 cell differentiation was detected by cDNA microarray, some of which were further confirmed by quantitative real time RT-PCR. At the same time, the expressions of these genes in NB4-R1 cells treated with ATRA and 8-CPT-cAM P alone or in combination, and in differentiation of primary cells from ATRA-induced newly diagnosed APL patients were detected by real time RT-PCR. The results showed that during differentiation of ATRA-induced NB4 cells, the expressions of genes related to calcium concentration had changed, the expression of downstream effectors in calcium pathway was up-regulated and confirmed by real time RT-PCR assay. The expression of genes related to calcium concentration did not change significantly when NB4-R1 cells were treated by ATRA or 8-CPT-cAMP alone, but expression changes of those genes were similar to the changes in ATRA-induced NB4 cell differentiation when NB4-R1 cells were treated by ATRA combined with 8-CPT-cAMP. In addition, the expression changes of those genes in ATRA-induced primary cells of patients with APL were also similar to changes in ATRA-induced NB4 cell differentiation. It is concluded that calcium pathway may be involved in ATRA-induced differentiation in APL cell.

Anomalous electrophoretic migration of newly synthesized ribosomal RNAs and their precursors from cells with DKC1 mutations.

Mutations in the X-linked gene, DKC1, encoding dyskerin, cause dyskeratosis congenita by leading to decreased telomerase activity and causing short telomeres. Dyskerin is also a pseudouridine synthase that modifies nascent ribosomal and other RNAs and it is not known if this function is affected by the mutations. Here we show that newly synthesized ribosomal RNA, extracted from human and mouse cells with pathogenic mutations, shows anomalous mobility in agarose gels under certain denaturation conditions. The anomalously migrating RNA is turned over rapidly. Analysis of ribosomal RNA in these cells suggests the altered mobility is due to inefficient pseudouridylation.

[Expression level changes of inhibitor of differentiation 1 during ATRA-induced acute promyelocytic leukemia cells differentiation].

OBJECTIVE: To study the role of inhibitor of differentiation 1 (ID1) in ATRA-induced acute promyelocytic leukemia (APL) cells differentiation. METHODS: The expression of ID1 was detected by cDNA microarray, cycloheximide inhibition test, real-time RT-PCR and western blot. RESULTS: The expression of ID1 gene was up-regulated in ATRA-induced NB4 cells and APL cells from two patients and was independent on other proteins synthesis. ID1 expression level reached the peak at 2 h in NB4 cells induced by ATRA, its relative expression level was (359.4 +/- 48.7)-fold greater than control. ID1 expression level reached the peak at 2 h in bone marrow cells from APL patents treated with ATRA, and its level detected 3 times in one of the patient was (311.1 +/- 48.7) fold of control. The expression of ID1 protein was not up-regulated in ATRA resistant NB4-R2 cells after ATRA treatment. CONCLUSION: ID1 may be involved in ATRA-induced granulocytic differentiation as an ATRA-targeted gene.

Coordination of intrinsic, extrinsic, and endoplasmic reticulum-mediated apoptosis by imatinib mesylate combined with arsenic trioxide in chronic myeloid leukemia.

A treatment strategy that combines arsenic trioxide (ATO) with the tyrosine kinase inhibitor imatinib mesylate (STI571, Gleevec) appears to induce markedly more cell apoptosis than imatinib mesylate alone in chronic myeloid leukemia (CML). To understand the mechanisms underlying the synergistic/additive action of these agents, we applied cDNA microarrays, component plane presentation integrated self-organizing map (CPP-SOM), and methods of protein biochemistry to study cell apoptosis induced by imatinib mesylate, ATO, and the combination of the 2 agents in the CML cell line K562. Numerous features with temporospatial relationships were revealed, indicating the coordinated regulation of molecular networks from various aspects of proapoptotic and apoptotic activities in CML. Imatinib mesylate appears to induce mainly the intrinsic pathway of cell apoptosis, whereas ATO induces the endoplasmic reticulum (ER) stress-mediated pathway of cell apoptosis, and the combination of the 2 agents seems to more effectively induce the intrinsic, extrinsic, and ER stress-mediated pathways of cell apoptosis, which results in a more effective and efficient induction of programmed cell death in K562 cells. This finding appears to be supported also by data derived from bone marrow cells of 2 patients with CML, one in chronic phase and the other in blast-crisis phase of the disease.

Systems analysis of transcriptome and proteome in retinoic acid/arsenic trioxide-induced cell differentiation/apoptosis of promyelocytic leukemia.

Understanding the complexity and dynamics of cancer cells in response to effective therapy requires hypothesis-driven, quantitative, and high-throughput measurement of genes and proteins at both spatial and temporal levels. This study was designed to gain insights into molecular networks underlying the clinical synergy between retinoic acid (RA) and arsenic trioxide (ATO) in acute promyelocytic leukemia (APL), which results in a high-quality disease-free survival in most patients after consolidation with conventional chemotherapy. We have applied an approach integrating cDNA microarray, 2D gel electrophoresis with MS, and methods of computational biology to study the effects on APL cell line NB4 treated with RA, ATO, and the combination of the two agents and collected in a time series. Numerous features were revealed that indicated the coordinated regulation of molecular networks from various aspects of granulocytic differentiation and apoptosis at the transcriptome and proteome levels. These features include an array of transcription factors and cofactors, activation of calcium signaling, stimulation of the IFN pathway, activation of the proteasome system, degradation of the PML-RARalpha oncoprotein, restoration of the nuclear body, cell-cycle arrest, and gain of apoptotic potential. Hence, this investigation has provided not only a detailed understanding of the combined therapeutic effects of RA/ATO in APL but also a road map to approach hematopoietic malignancies at the systems level.