A review on effect of genetic features on treatment responses in acute myeloid leukemia

Chromosomal Analysis in Lineage-Specific Mouse Hematopoietic Stem Cells and Progenitors

Hematopoiesis is maintained throughout life from the hematopoietic stem cell niche in which hematopoietic stem cells and lineage-specific hematopoietic progenitors (HSPCs) reside and regulate hematopoiesis. Meanwhile, HSPCs behavior is modulated by both cell intrinsic (e.g., transcriptional factors) and cell extrinsic (e.g., cytokines) factors. Dysregulation of these factors can alter HSPCs function, leading to disrupted hematopoiesis, cellular changes, and subsequent hematological diseases and malignancies. Moreover, it has been reported that chromosomal aberration (CA) in HSPCs following exposure to carcinogenic or genotoxic agents can initiate leukemia stem cells (LSCs) formation which lays a fundamental mechanism in leukemogenesis. Despite reported studies concerning the chromosomal integrity in HSPCs, CA analysis in lineage-specific HSPCs remains scarce. This indicates a need for a laboratory technique that allows the study of CA in specific HSPCs subpopulations comprising differential hematopoietic lineages. Thus, this chapter focuses on the structural (clastogenicity) and numerical (aneugenicity) form of CA analysis in lineage-specific HSPCs comprised of myeloid, erythroid and lymphoid lineages.In this protocol, we describe how to perform CA analysis in lineage-specific HSPCs derived from freshly isolated mouse bone marrow cells (MBMCs) using the combined techniques of colony-forming unit (CFU) and karyotyping. Prior to CA analysis, lineage-specific HSPCs for myeloid, erythroid, and lymphoid were enriched through colony-forming unit (CFU) assay. CFU assay assesses the proliferative ability and differentiation potential of an individual HSPC within a sample. About 6 to 14 days of cultures are required depending on the type of HSPCs lineage. The optimal duration is crucial to achieve sufficient colony growth that is needed for accurate CFU analysis via morphological identification and colony counting. Then, the CA focusing on clastogenicity and aneugenicity anomalies in respective HSPCs lineage for myeloid, erythroid and Pre-B lymphoid were investigated. The resulted karyotypes were classified according to the types of CA known as Robertsonian (Rb) translocation, hyperploidy or complex. We believe our protocol offers a significant contribution to be utilized as a reference method for chromosomal analysis in lineage-specific HSPCs subpopulations.

Linking Benzene, in Utero Carcinogenicity and Fetal Hematopoietic Stem Cell Niches: A Mechanistic Review

Previous research reported that prolonged benzene exposure during in utero fetal development causes greater fetal abnormalities than in adult-stage exposure. This phenomenon increases the risk for disease development at the fetal stage, particularly carcinogenesis, which is mainly associated with hematological malignancies. Benzene has been reported to potentially act via multiple modes of action that target the hematopoietic stem cell (HSCs) niche, a complex microenvironment in which HSCs and multilineage hematopoietic stem and progenitor cells (HSPCs) reside. Oxidative stress, chromosomal aberration and epigenetic modification are among the known mechanisms mediating benzene-induced genetic and epigenetic modification in fetal stem cells leading to in utero carcinogenesis. Hence, it is crucial to monitor exposure to carcinogenic benzene via environmental, occupational or lifestyle factors among pregnant women. Benzene is a well-known cause of adult leukemia. However, proof of benzene involvement with childhood leukemia remains scarce despite previously reported research linking incidences of hematological disorders and maternal benzene exposure. Furthermore, accumulating evidence has shown that maternal benzene exposure is able to alter the developmental and functional properties of HSPCs, leading to hematological disorders in fetus and children. Since HSPCs are parental blood cells that regulate hematopoiesis during the fetal and adult stages, benzene exposure that targets HSPCs may induce damage to the population and trigger the development of hematological diseases. Therefore, the mechanism of in utero carcinogenicity by benzene in targeting fetal HSPCs is the primary focus of this review.