Calming down T cell acute leukemia

New biomarkers and therapeutic strategies in acute lymphoblastic leukemias: Recent advances

Acute lymphoblastic leukemia (ALL) represents a heterogeneous group of hematologic malignancies, and it is normally characterized by an aberrant proliferation of immature lymphoid cells. Moreover, dysregulation of multiple signaling pathways that normally regulate cellular transcription, growth, translation, and proliferation is frequently encountered in this malignancy. ALL is the most frequent tumor in childhood, and adult ALL patients still correlate with poor survival. This review focuses on modern therapies in ALL that move beyond standard chemotherapy, with a particular emphasis on immunotherapeutic approaches as new treatment strategies. Bi-specific T-cell Engagers (BiTE) antibodies, the chimeric antigen receptor (CAR)-T cells, or CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats [CRISPR]-associated nuclease 9) represent other new innovative approaches for this disease. Target and tailored therapy could make the difference in previously untreatable cases, i.e., precision and personalized medicine. Clinical trials will help to select the most efficient novel therapies in ALL management and to integrate them with existing treatments to achieve durable cures.

Targeting the phosphatidylinositol 3-kinase/Akt/mechanistic target of rapamycin signaling pathway in B-lineage acute lymphoblastic leukemia: An update

Despite considerable progress in treatment protocols, B-lineage acute lymphoblastic leukemia (B-ALL) displays a poor prognosis in about 15-20% of pediatric cases and about 60% of adult patients. In addition, life-long irreversible late effects from chemo- and radiation therapy, including secondary malignancies, are a growing problem for leukemia survivors. Targeted therapy holds promising perspectives for cancer treatment as it may be more effective and have fewer side effects than conventional therapies. The phosphatidylinositol 3-phosphate kinase (PI3K)/Akt/mechanistic target of rapamycin (mTOR) signaling pathway is a key regulatory cascade which controls proliferation, survival and drug-resistance of cancer cells, and it is frequently upregulated in the different subtypes of B-ALL, where it plays important roles in the pathophysiology, maintenance and progression of the disease. Moreover, activation of this signaling cascade portends a poorer prognosis in both pediatric and adult B-ALL patients. Promising preclinical data on PI3K/Akt/mTOR inhibitors have documented their anticancer activity in B-ALL and some of these novel drugs have entered clinical trials as they could lead to a longer event-free survival and reduce therapy-associated toxicity for patients with B-ALL. This review highlights the current status of PI3K/Akt/mTOR inhibitors in B-ALL, with an emphasis on emerging evidence of the superior efficacy of synergistic combinations involving the use of traditional chemotherapeutics or other novel, targeted agents.

Flavokawain B inhibits the growth of acute lymphoblastic leukemia cells via p53 and caspase-dependent mechanisms

The development of novel chemotherapeutic drugs is needed for the treatment of patients with acute lymphoblastic leukemia (ALL). In this study, the anti-leukemic effect and the potential molecular mechanisms of action of flavokawain B on ALL were investigated. Flavokawain B was found to significantly inhibit the cellular proliferation of B-ALL and T-ALL cell lines in a dose-dependent manner. It also induced cellular apoptosis by increasing the expression of p53, Bax and Puma, and activating the cleavage of caspase-3 and poly ADP-ribose polymerase (PARP). Furthermore, the enhancement of p53-dependent apoptosis by flavokawain B could be rescued by pifithrin-α, a pharmacological inhibitor of p53 transcriptional activity. Moreover, the proliferation of leukemia blast cells from 16 patients with ALL was inhibited by flavokawain B, and tumor growth in xenograft mice was also suppressed by this drug. In conclusion, our results demonstrate the therapeutic potential of flavokawain B for the treatment of ALL.

MicroRNA-100/99a, deregulated in acute lymphoblastic leukaemia, suppress proliferation and promote apoptosis by regulating the FKBP51 and IGF1R/mTOR signalling pathways

Background:

MicroRNAs alter multiple cell processes and thus influence tumour carcinogenesis and progression. MiR-100 and miR-99a have been reported to be aberrantly expressed in acute leukaemia. In this study, we focused on their functions in acute lymphoblastic leukaemia (ALL) and the molecular networks in which they are involved.

Methods:

MiR-100 and miR-99a expression levels were measured in acute leukaemia patients by qRT–PCR. Kaplan−Meier analysis and log-rank tests were used to calculate the survival rate. Three human ALL cell lines were studied. Apoptosis and proliferation were analysed using siRNA transfection, western blot and flow cytometry.

Results:

In vivo, miR-100 and miR-99a were down-regulated in 111 ALL patients, especially in high-risk groups; their expression levels were correlated with the patient's 5-year survival. In vitro, the restoration of miR-100 and miR-99a in ALL cells suppressed cell proliferation and increased dexamethasone-induced cell apoptosis. Ectopic expression of miR-100 and miR-99a targeted FK506-binding protein 51 (FKBP51) and, in turn, influenced glucocorticoid receptor (GR) activity. Meanwhile, miR-100 and miR-99a overexpression inhibited the expression of IGF1R and mTOR and their downstream oncogene MCL1.

Conclusion:

MiR-100 and miR-99a have critical roles in altering cellular processes by targeting both the FKBP51 and IGF1R/mTOR signalling pathways in vitro and might represent a potential novel strategy for ALL treatment.