Deleterious point mutations in T-cell acute lymphoblastic leukemia: Mechanistic insights into leukemogenesis

Association of Leukemia With ABO Blood Group Distribution and Discrepancy: A Review Article

The ABO system is an essential blood group in clinical transfusion medicine implicated in several human diseases. The ABO system has been investigated for over a century, with various studies exploring potential links to disease susceptibility. The study examines the possible relationship between leukemia and the distribution and the ABO blood group system discrepancy. A comprehensive review was conducted on the recommended databases to review the ABO blood groups, their association with leukemia, and the expected changes in blood groups among leukemia patients. The study highlights different kinds of leukemia, such as acute lymphocytic leukemia (ALL), acute myeloid leukemia (AML), chronic myeloid leukemia (CML), and chronic lymphocytic leukemia (CLL), their characteristics, and their relationship with ABO blood groups. The document concludes that studying ABO blood group distributions among leukemia patients showed that the most common blood group in acute leukemia is the A group, while in chronic leukemia, the O group is predominant; more studies are required. This study also confirmed an association between leukemia and ABO blood group discrepancy.

Wilms' tumor gene 1 in hematological malignancies: friend or foe?

Wilms' tumor gene 1 (WT1) is a transcription and post-translational factor that has a crucial role in the biological and pathological processes of several human malignancies. For hematological malignancies, WT1 overexpression or mutation has been found in leukemia and myelodysplastic syndrome. About 70-90% of acute myeloid leukemia patients showed WT1 overexpression, and 6-15% of patients carried WT1 mutations. WT1 has been widely regarded as a marker for monitoring minimal residual disease in acute myeloid leukemia. Many researchers were interested in developing WT1 targeting therapy. In this review, we summarized biological and pathological functions, correlation with other genes and clinical features, prognosis value and targeting therapy of WT1 in hematological features.

Evaluation of potential role of R-loop and G-quadruplex DNA in the fragility of c-MYC during chromosomal translocation associated with Burkitt's lymphoma

t(8;14) translocation is the hallmark of Burkitt's lymphoma and results in c-MYC deregulation. During the translocation, c-MYC gene on chromosome 8 gets juxtaposed to the Ig switch regions on chromosome 14. Although the promoter of c-MYC has been investigated for its mechanism of fragility, little is known about other c-MYC breakpoint regions. We have analyzed the translocation break points at the exon 1/intron 1 of c-MYC locus from patients with Burkitt's lymphoma. Results showed that the breakpoint region, when present on a plasmid, could fold into an R-loop confirmation in a transcription-dependent manner. Sodium bisulfite modification assay revealed significant single-strandedness on chromosomal DNA of Burkitt's lymphoma cell line, Raji, and normal lymphocytes, revealing distinct R-loops covering up to 100 bp region. Besides, ChIP-DRIP analysis reveals that the R-loop antibody can bind to the breakpoint region. Further, we show the formation of stable parallel intramolecular G-quadruplex on non-template strand of the genome. Finally, incubation of purified AID in vitro or overexpression of AID within the cells led to enhanced mutation frequency at the c-MYC breakpoint region. Interestingly, anti-γH2AX can bind to DSBs generated at the c-MYC breakpoint region within the cells. The formation of R-loop and G-quadruplex was found to be mutually exclusive. Therefore, our results suggest that AID can bind to the single-stranded region of the R-loop and G4 DNA, leading to the deamination of cytosines to uracil and induction of DNA breaks in one of the DNA strands, leading to double-strand break, which could culminate in t(8;14) chromosomal translocation.

Design and Synthesis of Ketenimine Sulfonamide Conjugates through Multicomponent Reactions; A Combined Cytotoxic Analysis and Computational Exploration

Multicomponent reactions involving zwitterion generated from dimethyl acetylenedicarboxylate, aryl sulfonamide, and isocyanide to generate sulfonamide-conjugated ketenimines is reported. The synthetic strategy adopted is highly atom economical and stereoselective. Ketenimine sulfonamide analogues are key intermediates for further synthetic conversions to generate a combinatorial library of compounds. Furthermore, sulfonamide compounds are known to possess a broad spectrum of biological applications. All the novel molecules synthesized exhibit the potential to target the nonhomologous DNA end-joining (NHEJ) pathway with cytotoxic ability. Computational studies compliment the in vitro biological assays of the 8 small-molecule inhibitors. DNA double-strand breaks (DSBs) are considered as the most lethal among different DNA damages. NHEJ repairs about 70% of the DSBs generated in cells within mammals. The DNA-dependent protein kinase catalytic subunit is one of the PI3 kinases associated with NHEJ. Compounds DK01-DK08 were investigated for their ability to induce cancer cell death by treating with two leukemic cell lines where NHEJ is high. Results showed that bromoaryl (DK04)- and nitroaryl (DK05)-conjugated molecules showed excellent biological activity, having IC50 values of ∼2 μM in Nalm6 cell lines.

The role of lysine-specific demethylase 6A (KDM6A) in tumorigenesis and its therapeutic potentials in cancer therapy

Histone demethylation is a key post-translational modification of chromatin, and its dysregulation affects a wide array of nuclear activities including the maintenance of genome integrity, transcriptional regulation, and epigenetic inheritance. Lysine specific demethylase 6A (KDM6A, also known as UTX) is an Fe²⁺- and α-ketoglutarate- dependent oxidase which belongs to KDM6 Jumonji histone demethylase subfamily, and it can remove mono-, di- and tri-methyl groups from methylated lysine 27 of histone H3 (H3K27me1/2/3). Mounting studies indicate that KDM6A is responsible for driving multiple human diseases, particularly cancers and pharmacological inhibition of KDM6A is an effective strategy to treat varieties of KDM6A-amplified cancers in cellulo and in vivo. Although there are several reviews on the roles of KDM6 subfamily in cancer development and therapy, all of them only simply introduce the roles of KDM6A in cancer without systematically summarizing the specific mechanisms of KDM6A in tumorigenesis, which greatly limits the advances on the understanding of roles KDM6A in varieties of cancers, discovering targeting selective KDM6A inhibitors, and exploring the adaptive profiles of KDM6A antagonists. Herein, we present the structure and functions of KDM6A, simply outline the functions of KDM6A in homeostasis and non-cancer diseases, summarize the role of KDM6A and its distinct target genes/ligand proteins in development of varieties of cancers, systematically classify KDM6A inhibitors, sum up the difficulties encountered in the research of KDM6A and the discovery of related drugs, and provide the corresponding solutions, which will contribute to understanding the roles of KDM6A in carcinogenesis and advancing the progression of KDM6A as a drug target in cancer therapy.

Understanding the Roles of the Hedgehog Signaling Pathway during T-Cell Lymphopoiesis and in T-Cell Acute Lymphoblastic Leukemia (T-ALL)

The Hedgehog (HH) signaling network is one of the main regulators of invertebrate and vertebrate embryonic development. Along with other networks, such as NOTCH and WNT, HH signaling specifies both the early patterning and the polarity events as well as the subsequent organ formation via the temporal and spatial regulation of cell proliferation and differentiation. However, aberrant activation of HH signaling has been identified in a broad range of malignant disorders, where it positively influences proliferation, survival, and therapeutic resistance of neoplastic cells. Inhibitors targeting the HH pathway have been tested in preclinical cancer models. The HH pathway is also overactive in other blood malignancies, including T-cell acute lymphoblastic leukemia (T-ALL). This review is intended to summarize our knowledge of the biological roles and pathophysiology of the HH pathway during normal T-cell lymphopoiesis and in T-ALL. In addition, we will discuss potential therapeutic strategies that might expand the clinical usefulness of drugs targeting the HH pathway in T-ALL.

Identification and characterization of mercaptopyrimidine-based small molecules as inhibitors of nonhomologous DNA end joining

Mercaptopyrimidine derivatives are heterocyclic compounds with potent biological activities including antiproliferative, antibacterial, and anti-inflammatory properties. The present study describes the synthesis and characterization of several mercaptopyrimidine derivatives through condensation of 5,6-diamino-2-mercaptopyrimidin-4-ol with various heterocyclic and aromatic aldehydes. Previous studies have shown that SCR7, synthesized from 5,6-diamino-2-mercaptopyrimidin-4-ol, induced cytotoxicity by targeting cancer cells by primarily inhibiting DNA Ligase IV involved in nonhomologous end joining, one of the major DNA double-strand break repair pathways. Inhibition of DNA repair pathways is considered as an important strategy for cancer therapy. Due to limitations of SCR7 in terms of IC₅₀ in cancer cells, here we have designed, synthesized, and characterized potent derivatives of SCR7 using 5,6-diamino-2-mercaptopyrimidin-4-ol as the starting material. Several synthesized imine compounds exhibited significant improvement in inhibition of end joining and cytotoxicity up to 27-fold lower concentrations than SCR7. Among these, two compounds, SCR116 and SCR132, showed increased cancer cell death in a Ligase IV-dependent manner. Treatment with the compounds also led to reduction in V(D)J recombination efficiency, cell cycle arrest at G2/M phase, accumulation of double-strand breaks inside cells, and improved anti-cancer potential when combined with γ-radiation and radiomimetic drugs. Thus, we describe novel inhibitors of NHEJ with higher efficacy and potential, which can be developed as cancer therapeutics.

Nonamer dependent RAG cleavage at CpGs can explain mechanism of chromosomal translocations associated to lymphoid cancers

Chromosomal translocations are considered as one of the major causes of lymphoid cancers. RAG complex, which is responsible for V(D)J recombination, can also cleave non-B DNA structures and cryptic RSSs in the genome leading to chromosomal translocations. The mechanism and factors regulating the illegitimate function of RAGs resulting in oncogenesis are largely unknown. Upon in silico analysis of 3760 chromosomal translocations from lymphoid cancer patients, we find that 93% of the translocation breakpoints possess adjacent cryptic nonamers (RAG binding sequences), of which 77% had CpGs in proximity. As a proof of principle, we show that RAGs can efficiently bind to cryptic nonamers present at multiple fragile regions and cleave at adjacent mismatches generated to mimic the deamination of CpGs. ChIP studies reveal that RAGs can indeed recognize these fragile sites on a chromatin context inside the cell. Finally, we show that AID, the cytidine deaminase, plays a significant role during the generation of mismatches at CpGs and reconstitute the process of RAG-dependent generation of DNA breaks both in vitro and inside the cells. Thus, we propose a novel mechanism for generation of chromosomal translocation, where RAGs bind to the cryptic nonamer sequences and direct cleavage at adjacent mismatch generated due to deamination of meCpGs or cytosines.

Unveiling the N-Terminal Homodimerization of BCL11B by Hybrid Solvent Replica-Exchange Simulations

Transcription factors play a crucial role in regulating biological processes such as cell growth, differentiation, organ development and cellular signaling. Within this group, proteins equipped with zinc finger motifs (ZFs) represent the largest family of sequence-specific DNA-binding transcription regulators. Numerous studies have proven the fundamental role of BCL11B for a variety of tissues and organs such as central nervous system, T cells, skin, teeth, and mammary glands. In a previous work we identified a novel atypical zinc finger domain (CCHC-ZF) which serves as a dimerization interface of BCL11B. This domain and formation of the dimer were shown to be critically important for efficient regulation of the BCL11B target genes and could therefore represent a promising target for novel drug therapies. Here, we report the structural basis for BCL11B-BCL11B interaction mediated by the N-terminal ZF domain. By combining structure prediction algorithms, enhanced sampling molecular dynamics and fluorescence resonance energy transfer (FRET) approaches, we identified amino acid residues indispensable for the formation of the single ZF domain and directly involved in forming the dimer interface. These findings not only provide deep insight into how BCL11B acquires its active structure but also represent an important step towards rational design or selection of potential inhibitors.