Targeting steroid resistance in T-cell acute lymphoblastic leukemia

The histone methyltransferase KMT2D maintains cellular glucocorticoid responsiveness by shielding the glucocorticoid receptor from degradation

Because of their ability to induce lymphocyte apoptosis, glucocorticoids (GC) are widely used to treat hematological malignancies such as lymphomas and multiple myeloma. Their effectiveness is often limited, however, due to the development of glucocorticoid resistance by a variety of molecular mechanisms. Here we performed an unbiased genome-wide CRISPR screen with the human T-cell leukemia cell line Jurkat to find previously unidentified genes required for GC-induced apoptosis. One such gene was KMT2D (also known as MLL2 or MLL4), which encodes a histone lysine methyltransferase whose mutations are associated with a variety of cancers, blood malignancies in particular, and are considered markers of poor prognosis. Knockout of KMT2D by CRISPR/Cas9 gene editing in Jurkat and several multiple myeloma cell lines downregulated GR protein expression. Surprisingly, this was not due to a reduction in GR transcripts, but rather to a decrease in the protein's half-life, primarily due to proteasomal degradation. Reconstitution of KMT2D expression restored GR levels. In contrast to the known ability of KMT2D to control gene transcription through covalent histone methylation, KMT2D-mediated upregulation of GR levels did not require its methyltransferase activity. Co-immunoprecipitation and proximity ligation assays found constitutive binding of KMT2D to the GR, which was enhanced in the presence of GC. These observations reveal KMT2D to be essential for the stabilization of cellular GR levels, and suggest a possible mechanism by which KMT2D mutations may lead to GC resistance in some malignancies.

Investigation on the mechanism of androsta-4,6,8,14-tetraene-3,11,16-trione against acute lymphoblastic leukemia

Steroids are potential anti-leukemia agents, and Epigynum auritum is a Yunnan folk medicine with high levels of androsterone, pregnane, and steroid derivatives. However, the underlying therapeutic mechanism of androsta-4,6,8,14-tetraene-3,11,16-trione (ATT), an androsterone isolated from Epigynum auritum, is not yet clear. This study aimed to explore the anti-leukemia mechanism of ATT using molecular biology, network pharmacology, and molecular docking technology. The cell viability results showed that ATT had an anti-proliferation effect in acute lymphoblastic leukemia cells (CEM/C1, MOLT-4, Jurkat, BALL-1, Nalm-6, and RS4;11). Further studies showed that ATT reduced the mitochondrial membrane potential in B-cell acute lymphoblastic leukemia cell lines (BALL-1, Nalm-6, and RS4;11) and induced cell cycle arrest in MOLT-4 and BALL-1. ATT induced BALL-1 cell apoptosis by activating Caspase 3/7 activity and causing DNA fragmentation. Network pharmacology results suggested that ATT exerts its anti-leukemia activity via the PI3K/Akt signaling pathway. In addition, molecular docking analysis showed that ATT had high scores in docking with PTGS2, NR3C1, and AR. Western blotting results showed that ATT reduced the relative protein level of P-PI3K and P-Akt, thereby increasing the relative level of pro-apoptosis protein Bax and reducing the relative level of anti-apoptosis protein Bcl-2, the apoptosis downstream protein pro-caspase3, and cell proliferation-related proteins (P-GSK3B and CyclinD1). In conclusion, these results demonstrated that ATT could be a potential candidate drug with apoptosis-induction and cell cycle arrest effects for further investigation in acute lymphoblastic leukemia therapy.

Clonal evolution dissection reveals that a high MSI2 level promotes chemoresistance in T-cell acute lymphoblastic leukemia

ABSTRACT

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive cancer with resistant clonal propagation in recurrence. We performed high-throughput droplet-based 5' single-cell RNA with paired T-cell receptor (TCR) sequencing of paired diagnosis-relapse (Dx_Rel) T-ALL samples to dissect the clonal diversities. Two leukemic evolutionary patterns, "clonal shift" and "clonal drift" were unveiled. Targeted single-cell DNA sequencing of paired Dx_Rel T-ALL samples further corroborated the existence of the 2 contrasting clonal evolution patterns, revealing that dynamic transcriptional variation might cause the mutationally static clones to evolve chemotherapy resistance. Analysis of commonly enriched drifted gene signatures showed expression of the RNA-binding protein MSI2 was significantly upregulated in the persistent TCR clonotypes at relapse. Integrated in vitro and in vivo functional studies suggested that MSI2 contributed to the proliferation of T-ALL and promoted chemotherapy resistance through the posttranscriptional regulation of MYC, pinpointing MSI2 as an informative biomarker and novel therapeutic target in T-ALL.

Targeting TYK2 for Fighting Diseases: Recent Advance of TYK2 Inhibitors

TYK2 (tyrosine-protein kinase 2) is a non-receptor protein kinase belonging to the JAK family and is closely associated with various diseases, such as psoriasis, inflammatory bowel disease, systemic lupus erythematosus. TYK2 activates the downstream proteins STAT1-5 by participating in the signal transduction of immune factors such as IL-12, IL-23, and IL-10, resulting in immune expression. The activity of the inhibitor TYK2 can effectively block the transduction of excessive immune signals and treat diseases. TYK2 inhibitors are divided into two types of inhibitors according to the different binding sites. One is a TYK2 inhibitor that binds to JH2 and inhibits its activity through an allosteric mechanism. The representative inhibitor is BMS-986165, developed by Bristol-Myers Squibb. The other class binds to the JH1 adenosine triphosphate (ATP) site and prevents the catalytic activity of the kinase by blocking ATP and downstream phosphorylation. This paper mainly introduces the protein structure, signaling pathway, synthesis, structure-activity relationship and clinical research of TYK2 inhibitors.

Beyond Corticoresistance, A Paradoxical Corticosensitivity Induced by Corticosteroid Therapy in Pediatric Acute Lymphoblastic Leukemias

Known as a key effector in relapse of acute lymphoblastic leukemia (ALL), resistance to drug-induced apoptosis, is tightly considered one of the main prognostic factors for the disease. ALL cells are constantly developing cellular strategies to survive and resist therapeutic drugs. Glucocorticoids (GCs) are one of the most important agents used in the treatment of ALL due to their ability to induce cell death. The mechanisms of GC resistance of ALL cells are largely unknown and intense research is currently focused on this topic. Such resistance can involve different cellular and molecular mechanisms, including the modulation of signaling pathways involved in the regulation of proliferation, apoptosis, autophagy, metabolism, epigenetic modifications and tumor suppressors. Recently, several studies point to the paradoxical role of GCs in many survival processes that may lead to therapy-induced resistance in ALL cells, which we called "paradoxical corticosensitivity". In this review, we aim to summarize all findings on cell survival pathways paradoxically activated by GCs with an emphasis on previous and current knowledge on gene expression and signaling pathways.

Deep learning-based transcriptome model predicts survival of T-cell acute lymphoblastic leukemia

Identifying subgroups of T-cell acute lymphoblastic leukemia (T-ALL) with poor survival will significantly influence patient treatment options and improve patient survival expectations. Current efforts to predict T-ALL survival expectations in multiple patient cohorts are lacking. A deep learning (DL)-based model was developed to determine the prognostic staging of T-ALL patients. We used transcriptome sequencing data from TARGET to build a DL-based survival model using 265 T-ALL patients. We found that patients could be divided into two subgroups (K0 and K1) with significant difference (P< 0.0001) in survival rate. The more malignant subgroup was significantly associated with some tumor-related signaling pathways, such as PI3K-Akt, cGMP-PKG and TGF-beta signaling pathway. DL-based model showed good performance in a cohort of patients from our clinical center (P = 0.0248). T-ALL patients survival was successfully predicted using a DL-based model, and we hope to apply it to clinical practice in the future.

Therapeutic targeting of LCK tyrosine kinase and mTOR signaling in T-cell acute lymphoblastic leukemia

Relapse and refractory T-cell acute lymphoblastic leukemia (T-ALL) has a poor prognosis, and new combination therapies are sorely needed. Here, we used an ex vivo high-throughput screening platform to identify drug combinations that kill zebrafish T-ALL and then validated top drug combinations for preclinical efficacy in human disease. This work uncovered potent drug synergies between AKT/mTORC1 (mammalian target of rapamycin complex 1) inhibitors and the general tyrosine kinase inhibitor dasatinib. Importantly, these same drug combinations effectively killed a subset of relapse and dexamethasone-resistant zebrafish T-ALL. Clinical trials are currently underway using the combination of mTORC1 inhibitor temsirolimus and dasatinib in other pediatric cancer indications, leading us to prioritize this therapy for preclinical testing. This combination effectively curbed T-ALL growth in human cell lines and primary human T-ALL and was well tolerated and effective in suppressing leukemia growth in patient-derived xenografts (PDX) grown in mice. Mechanistically, dasatinib inhibited phosphorylation and activation of the lymphocyte-specific protein tyrosine kinase (LCK) to blunt the T-cell receptor (TCR) signaling pathway, and when complexed with mTORC1 inhibition, induced potent T-ALL cell killing through reducing MCL-1 protein expression. In total, our work uncovered unexpected roles for the LCK kinase and its regulation of downstream TCR signaling in suppressing apoptosis and driving continued leukemia growth. Analysis of a wide array of primary human T-ALLs and PDXs grown in mice suggest that combination of temsirolimus and dasatinib treatment will be efficacious for a large fraction of human T-ALLs.

DT7 peptide-modified lecithin nanoparticles co-loaded with γ-secretase inhibitor and dexamethasone efficiently inhibit T-cell acute lymphoblastic leukemia and reduce gastrointestinal toxicity

T-cell acute lymphoblastic leukemia (T-ALL) is a serious hematologic malignancy and glucocorticoid resistance is the main recurrent cause for a high relapsed and death rate. Here, we proposed an effective therapeutic regimen of combining gamma-secretase inhibitors (GSIs) with dexamethasone (DEX) to overcome glucocorticoid resistance. Moreover, the bone marrow targeting DT7 peptide-modified lecithin nanoparticles co-loaded with DEX and GSI (TLnp/D&G) were developed to enhance T-ALL cells recognition and endocytosis. In vitro cytotoxicity studies showed that TLnp/D&G significantly inhibited cell survival and promoted apoptosis of T-ALL cells. Mechanically, we found that GSIs promoted DEX-induced cell apoptosis by two main synergetic mechanisms: 1) GSIs significantly upregulated glucocorticoid receptor (GR) expression in T-ALL and restored the glucocorticoid-induced pro-apoptotic response. 2) Both DEX and GSI synergistically inhibited BCL2 and suppressed the survival of T-ALL cells. Furthermore, in vivo studies demonstrated that TLnp/D&G showed high bone marrow accumulation and better antileukemic efficacy both in leukemia bearing models and in systemic Notch1-induced T-ALL models, with excellent biosafety and reduced gastrointestinal toxicity. Overall, our study provides new strategies for the treatment of T-ALL and promising bone marrow targeting systems with high transformation potential.

Gene Mutations Related to Glucocorticoid Resistance in Pediatric Acute Lymphoblastic Leukemia

OBJECTIVE

To investigate the correlation between gene mutations and glucocorticoid resistance in pediatric acute lymphoblastic leukemia (ALL).

METHODS

A total of 71 children with ALL admitted to our center between September 2019 and September 2021 were enrolled. DNA obtained from bone marrow or peripheral blood samples at initial diagnosis was used for genetic testing via whole exome sequencing. Meanwhile, patient clinical information was collected. Subsequently, the correlations of gene mutations with clinical features and glucocorticoid resistance were analyzed.

RESULTS

Of the 71 children enrolled, 61 (85.9%) had B-cell ALL (B-ALL) and 10 (14.1%) had T-cell ALL (T-ALL). The five genes with the highest mutation frequency in B-ALL were TTN (24.4%), FLT3 (14.6%), TP53 (14.6%), MUC16 (9.8%), and EPPK1 (9.8%). In contrast, those with the highest frequency in T-ALL were NOTCH1 (54.5%), FBXW7 (27.3%), TTN (27.3%), MUC16 (27.3%), and PHF6 (18.2%). Upon statistical analysis, TTN and NOTCH1 mutations were found to be associated with prednisone resistance. Further, TTN and MUC16 mutations were associated with a lower age at diagnosis, and NOTCH1 mutations were associated with T-ALL in female patients. Leukocyte counts and LDH levels did not differ based on the presence of any common gene mutation, and no association between these gene mutations and overall survival was observed.

CONCLUSIONS

Our study is the first to demonstrate the association between TTN mutation and glucocorticoid resistance in ALL. Our findings could guide strategies for overcoming drug resistance and aid in the development of drug targets.

Upregulation of leukemia-induced non-coding activator RNA (LUNAR1) predicts poor outcome in pediatric T-acute lymphoblastic leukemia

T-cell Acute Lymphoblastic Leukemia (T-ALL) accounts for around 10-15% of all lymphoblastic leukemia in children. Previous studies have proven that dysregulation of Leukemia-induced non-coding activator RNA-1 (LUNAR1) expression promotes T-ALL cell growth by enhancing the NOTCH1/IGF-1R signaling pathway. We aimed to investigate the prognostic value of LUNAR1 in pediatric T-ALL, in addition, to find out its association with NOTCH1 and IGF-1R. The LUNAR1, NOTCH1, and IGF-IR gene expression were measured in peripheral blood (PB) samples of l85 children with T-ALL and forty non-leukemic samples as a control group. Cox regression analysis revealed that overexpression of LUNAR1, NOTCH1, and IGF-IR was significantly correlated with poor prognosis, short overall survival, and progression-free survival. We concluded that LUNAR1 could serve as an independent prognostic biomarker for T-ALL in children.

T-Cell Acute Lymphoblastic Leukemia: Biomarkers and Their Clinical Usefulness

T-cell acute lymphoblastic leukemias (T-ALL) are immature lymphoid tumors localizing in the bone marrow, mediastinum, central nervous system, and lymphoid organs. They account for 10-15% of pediatric and about 25% of adult acute lymphoblastic leukemia (ALL) cases. It is a widely heterogeneous disease that is caused by the co-occurrence of multiple genetic abnormalities, which are acquired over time, and once accumulated, lead to full-blown leukemia. Recurrently affected genes deregulate pivotal cell processes, such as cycling (CDKN1B, RB1, TP53), signaling transduction (RAS pathway, IL7R/JAK/STAT, PI3K/AKT), epigenetics (PRC2 members, PHF6), and protein translation (RPL10, CNOT3). A remarkable role is played by NOTCH1 and CDKN2A, as they are altered in more than half of the cases. The activation of the NOTCH1 signaling affects thymocyte specification and development, while CDKN2A haploinsufficiency/inactivation, promotes cell cycle progression. Among recurrently involved oncogenes, a major role is exerted by T-cell-specific transcription factors, whose deregulated expression interferes with normal thymocyte development and causes a stage-specific differentiation arrest. Hence, TAL and/or LMO deregulation is typical of T-ALL with a mature phenotype (sCD3 positive) that of TLX1, NKX2-1, or TLX3, of cortical T-ALL (CD1a positive); HOXA and MEF2C are instead over-expressed in subsets of Early T-cell Precursor (ETP; immature phenotype) and early T-ALL. Among immature T-ALL, genomic alterations, that cause BCL11B transcriptional deregulation, identify a specific genetic subgroup. Although comprehensive cytogenetic and molecular studies have shed light on the genetic background of T-ALL, biomarkers are not currently adopted in the diagnostic workup of T-ALL, and only a limited number of studies have assessed their clinical implications. In this review, we will focus on recurrent T-ALL abnormalities that define specific leukemogenic pathways and on oncogenes/oncosuppressors that can serve as diagnostic biomarkers. Moreover, we will discuss how the complex genomic profile of T-ALL can be used to address and test innovative/targeted therapeutic options.

Jak-STAT Inhibition Mediates Romidepsin and Mechlorethamine Synergism in Cutaneous T-Cell Lymphoma

Sézary syndrome is an aggressive and disseminated form of cutaneous T-cell lymphoma associated with dismal prognosis in which the histone deacetylase inhibitor romidepsin has shown remarkable activity as a single agent. However, clinical responses to romidepsin are typically transient, highlighting the need for more effective therapies. In this study, we show synergistic antilymphoma effects of romidepsin in combination with mechlorethamine, an alkylating agent, in cutaneous T-cell lymphoma cell lines and primary samples with strong antitumor effects in an in vivo model of Sézary syndrome. Mechanistically, gene expression profiling points to abrogation of Jak/signal transducer and activator of transcription (STAT) signaling as an important mediator of this interaction. Consistently, the combination of mechlorethamine plus romidepsin resulted in downregulation of STAT5 phosphorylation in romidepsin-sensitive cell lines and primary Sézary syndrome samples, but not in romidepsin-resistant tumors. Moreover, in further support of Jak/STAT signaling as a modulator of romidepsin activity in cutaneous T-cell lymphoma, treatment with romidepsin in combination with Jak inhibitors resulted in markedly increased therapeutic responses. Overall, these results support a role for romidepsin plus mechlorethamine in combination in the treatment of cutaneous T-cell lymphoma and uncover a previously unrecognized role for Jak/STAT signaling in the response to romidepsin and romidepsin-based combination therapies in Sézary syndrome.

DNA Methylation in T-Cell Acute Lymphoblastic Leukemia: In Search for Clinical and Biological Meaning

Distinct DNA methylation signatures, related to different prognosis, have been observed across many cancers, including T-cell acute lymphoblastic leukemia (T-ALL), an aggressive hematological neoplasm. By global methylation analysis, two major phenotypes might be observed in T-ALL: hypermethylation related to better outcome and hypomethylation, which is a candidate marker of poor prognosis. Moreover, DNA methylation holds more than a clinical meaning. It reflects the replicative history of leukemic cells and most likely different mechanisms underlying leukemia development in these T-ALL subtypes. The elucidation of the mechanisms and aberrations specific to (epi-)genomic subtypes might pave the way towards predictive diagnostics and precision medicine in T-ALL. We present the current state of knowledge on the role of DNA methylation in T-ALL. We describe the involvement of DNA methylation in normal hematopoiesis and T-cell development, focusing on epigenetic aberrations contributing to this leukemia. We further review the research investigating distinct methylation phenotypes in T-ALL, related to different outcomes, pointing to the most recent research aimed to unravel the biological mechanisms behind differential methylation. We highlight how technological advancements facilitated broadening the perspective of the investigation into DNA methylation and how this has changed our understanding of the roles of this epigenetic modification in T-ALL.

Methylprednisolone potentiates tetrandrine pharmacodynamics against human T lymphoblastoid leukemia MOLT-4 cells via regulation of NF-κB activation and cell cycle transition

Low response to glucocorticoid (GC) predicts therapeutic failure in acute T lymphoblastic leukemia (T-ALL). The efficient and safe strategies are still required for the treatment of relapsed T-ALL. Our previous study revealed that tetrandrine induces apoptosis in human T lymphoblastoid leukemia cells possibly via activation of NF-κB. GCs are recognized as typical NF-κB inhibitors and are used for the treatment of T-ALL patients. In the present study, we examined whether methylprednisolone (MP) potentiates the cytotoxic effect of tetrandrine (TET) via NF-κB regulation by using human T lymphoblastoid leukemia MOLT-4 cells. WST-8 assay data showed that nM grade of MP increased cytotoxicity of TET against MOLT-4 cells in vitro. This effect seemed to be related to the potentiation of TET action by MP to induce apoptosis. Meanwhile, the combination also impeded the transition of cell cycle from G0/G1 phase to S phase. However, the regulation effect of this combination on cell cycle had no relationship with cyclin signaling pathway, since the drug-combination did not influence on the expression of cyclin A2/B1/D1 in MOLT-4 cells. On the other hand, the combination significantly inhibited the phosphorylation of NF-κB (p < 0.01). These results suggest that nM grade of MP potentiates the cytotoxic effect of TET possibly via regulation of NF-κB activation and "G0/G1 to S" phase transition in human T lymphoblastoid leukemia MOLT-4 cells. Combination of TET and MP may provide a new therapeutic strategy for relapsed T-ALL.

New Approaches to Treating Challenging Subtypes of ALL in AYA Patients

PURPOSE OF REVIEW

The treatment of acute lymphoblastic leukemia (ALL) in adolescent and young adult (AYA) patients has markedly improved with the adoption of pediatric-inspired protocols. However, there remain several subtypes of ALL that represent significant therapeutic challenges. Here, we review the current evidence guiding treatment of Philadelphia chromosome-positive (Ph+), Philadelphia chromosome-like (Ph-L), and early T-precursor (ETP) ALL in the AYA population.

RECENT FINDINGS

Clinical trials in Ph + ALL have demonstrated the superior efficacy of second- and third-generation tyrosine kinase inhibitors (TKIs) to induce and maintain remission. Current efforts now focus on determining the durability of these remissions and which patients will benefit from transplant. For Ph-like and ETP ALL, recent studies are investigating the addition of novel agents to standard treatment. The treatment of Ph + ALL has significantly improved with the addition of potent TKIs. However, the treatment of Ph-like and ETP ALL remains a challenge. At this time, the judicious use of allogenic transplant is the only current approach to modify this increased risk.

SIX6 is a TAL1-regulated transcription factor in T-ALL and associated with inferior outcome

T-cell acute lymphoblastic leukemia (T-ALL) is a hematological malignancy driven by abnormal activity of transcription factors. Here we report an aberrant expression of the developmental transcription factor SIX6 in the TAL1-subtype of T-ALL. Our results demonstrate that the binding of TAL1 and GATA3 transcription factors into an upstream enhancer element directly regulates SIX6 expression. High expression of SIX6 was associated with inferior event-free survival within three independent patient cohorts. At a functional level, CRISPR-Cas9-mediated knockout of the SIX6 gene in TAL1 positive Jurkat cells induced changes in genes associated with the mTOR-, K-RAS-, and TNFα-related molecular signatures but did not impair cell proliferation or viability. There was also no acceleration of T-ALL development within a Myc driven zebrafish tumor model in vivo. Taken together, our results show that SIX6 belongs to the TAL1 regulatory gene network in T-ALL but is alone insufficient to influence the development or maintenance of T-ALL.

Molecular mechanisms and therapeutic implications of tetrandrine and cepharanthine in T cell acute lymphoblastic leukemia and autoimmune diseases

Inappropriately activated T cells mediate autoimmune diseases and T cell acute lymphoblastic leukemia (T-ALL). Glucocorticoid and chemotherapeutic agents have largely extended lives of these patients. However, serious side effects and drug resistance often limit the prognosis of considerable number of the patients. The efficient treatment of autoimmune diseases or T-ALL with drug resistance remains an important unmet demand clinically. Bisbenzylisoquinoline alkaloids tetrandrine and cepharanthine have been applied for the treatment of certain types of autoimmune diseases and cancers, while studies on their action mechanisms and their further applications combined with glucocorticoids or chemotherapeutic agents remains to be expanded. This review introduced molecular mechanisms of tetrandrine and cepharanthine in T cells, including their therapeutic implications. Both tetrandrine and cepharnthine influence the growth of activated T cells via several kinds of signaling pathways, such as NF-κB, caspase cascades, cell cycle, MAPK, and PI3K/Akt/mTOR. According to recent preclinical and clinical studies, P-glycoprotein inhibitory effect of tetrandrine and cepharnthine could play a significant role on T cell-involved refractory diseases. Therefore, tetrandrine or cepharanthine combined with glucocorticoid or other anti-leukemia drugs would bring a new hope for patients with glucocorticoid-resistant autoimmune disease or refractory T-ALL accompanied with functional P-glycoprotein. In conclusion, bisbenzylisoquinoline alkaloids tetrandrine and cepharanthine can regulate several signaling pathways in abnormally activated T cells with low toxicity. Bisbenzylisoquinoline alkaloids deserve to be paid more attention as a lead compound to develop new drugs for the treatment of T cell-involved diseases in the future.

Tetrandrine enhances glucocorticoid receptor translocation possibly via inhibition of P-glycoprotein in daunorubicin-resistant human T lymphoblastoid leukemia cells

Glucocorticoids are used as anticancer and immunosuppressive agents, whereas glucocorticoid resistance has been observed in a significant fraction of patients due to overexpression of P-glycoprotein encoded by multi-drug resistance-1 gene. Tetrandrine is a bisbenzylisoquinoline alkaloid isolated from traditional herb Fangji. According to our previous report, tetrandrine potentiated glucocorticoid pharmacodynamics partially via inhibiting P-glycoprotein function. In the present study, we investigated whether glucocorticoid receptor translocation was influenced indirectly by tetrandrine via P-glycoprotein inhibition, using human T lymphoblastoid leukemia MOLT-4 cell line with little P-glycoprotein expression and its multidrug resistant sub-line MOLT-4/DNR exhibiting a large amount of P-glycoprotein. Molecular mechanism investigation suggested that overexpressed P-glycoprotein weakened the glucocorticoid receptor translocation in MOLT-4/DNR cells comparing with the parent MOLT-4 cells. Our data also suggested that tetrandrine enhanced nuclear glucocorticoid receptor translocation in MOLT-4/DNR cells indirectly by dual influences on P-glycoprotein, inhibiting the efflux function and downregulating the protein expression. Therefore, tetrandrine potentiated the cytotoxic effect of methylprednisolone against MOLT-4/DNR cells with less effects on MOLT-4 cells. These effects of tetrandrine were suggested to be beneficial for the treatment of glucocorticoid resistant diseases induced by the overexpression of P-glycoprotein.

hsa-miR-20b-5p and hsa-miR-363-3p Affect Expression of PTEN and BIM Tumor Suppressor Genes and Modulate Survival of T-ALL Cells In Vitro

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy arising from T lymphocyte precursors. We have previously shown by miRNA-seq, that miRNAs from the mir-106a-363 cluster are overexpressed in pediatric T-ALL. In silico analysis indicated their potential involvement in the regulation of apoptosis. Here, we aimed to test the hypothesis on the pro-tumorigenic roles of these miRNAs in T-ALL cells in vitro. We demonstrate, for the first time, that hsa-miR-20b-5p and hsa-miR-363-3p from the mir-106a-363 cluster, when upregulated in T-ALL cells in vitro, protect leukemic cells from apoptosis, enhance proliferation, and contribute to growth advantage. We show, using dual luciferase reporter assays, Ago2-RNA immunoprecipitation, RT-qPCR, and Western blots, that the oncogenic effects of these upregulated miRNAs might, at least in part, be mediated by the downregulation of two important tumor suppressor genes, PTEN and BIM, targeted by both miRNAs. Additionally, we demonstrate the cooperative effects of these two miRNAs by simultaneous inhibition of both miRNAs as compared to the inhibition of single miRNAs. We postulate that hsa-miR-20b-5p and hsa-miR-363-3p from the mir-106a-363 cluster might serve as oncomiRs in T-ALL, by contributing to post-transcriptional repression of key tumor suppressors, PTEN and BIM.

How I treat newly diagnosed T-cell acute lymphoblastic leukemia and T-cell lymphoblastic lymphoma in children

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy that has historically been associated with a very poor prognosis. Nevertheless, despite a lack of incorporation of novel agents, the development of intensified T-ALL-focused protocols has resulted in significant improvements in outcome in children. Through the use of several representative cases, we highlight the key changes that have driven these advances including asparaginase intensification, the use of induction dexamethasone, and the safe omission of cranial radiotherapy. We discuss the results of recent trials to explore key topics including the implementation of risk stratification with minimal residual disease measurement and how to treat high-risk subtypes such as early T-cell precursor ALL. In particular, we address current discrepancies in treatment between different cooperative groups, including the use of nelarabine, and provide rationales for current treatment protocols for both T-ALL and T-lymphoblastic lymphoma.