New acute myeloid leukemia-derived cell line: MUTZ-8 with 5q-

Choosing the Right Cell Line for Acute Myeloid Leukemia (AML) Research

Immortalized cell lines are widely used in vitro tools in oncology and hematology research. While these cell lines represent artificial systems and may accumulate genetic aberrations with each passage, they are still considered valuable models for pilot, preliminary, and screening studies. Despite their limitations, cell lines are cost-effective and provide repeatable and comparable results. Choosing the appropriate cell line for acute myeloid leukemia (AML) research is crucial for obtaining reliable and relevant results. Several factors should be considered when selecting a cell line for AML research, such as specific markers and genetic abnormalities associated with different subtypes of AML. It is also essential to evaluate the karyotype and mutational profile of the cell line, as these can influence the behavior and response to the treatment of the cells. In this review, we evaluate immortalized AML cell lines and discuss the issues surrounding them concerning the revised World Health Organization and the French-American-British classifications.

Jiyuan oridonin A induces differentiation of acute myeloid leukemia cells including leukemic stem-like cells

Acute myeloid leukemia (AML) is an aggressive form of hematological neoplasia characterized by failure of myeloid differentiation. AML is a leading cause of death from leukemia. Cytarabine chemotherapy resistance is a major source of refractory/relapsed AML. A major obstacle to the successful treatment of AML results from residual disease maintained by leukemic stem cells (LSCs), which are mostly resistant to conventional chemotherapy. Here, we determined the effect of a natural compound, Jiyuan oridonin A (JOA), on the differentiation blockade in the M2 subtype [particularly t (8;21)] of AML cells, M3 subtype of AML cells (APL cells), and leukemic stem-like cells both in vitro and in vivo. We found that JOA induced cell differentiation and suppressed the colony formation capacity in various AML cell lines (Kasumi-1, KG-1, MUTZ-8, NB4, and HL-60) without eliciting apoptosis. The mechanism of JOA-induced cell differentiation depends on the specificity of cell type. JOA mediated the differentiation of Kasumi-1 cells by activating the hematopoietic cell lineage signaling pathway, while inhibition of c-MYC was involved in the JOA-induced differentiation of NB4 cells. Moreover, JOA was identified to target leukemic stem-like cells by induced cell differentiation in vivo. These findings demonstrated that JOA could inhibit the proliferation of M2 and M3 subtypes of AML cells and leukemic stem-like cells by overcoming the differentiation blockade, which may offer a novel therapeutic strategy for AML to overcome relapse and drug resistance in patients with AML. Our findings highlight the possibility of using compounds like JOA as a promising differentiation-induced agent for the treatment of AML.

SOCS2: inhibitor of JAK2V617F-mediated signal transduction

Janus kinase 2 (JAK2)V617F-activating mutations (JAK2mu) occur in myeloproliferative disorders (MPDs) and myelodysplastic syndromes (MDSs). Cell lines MB-02, MUTZ-8, SET-2 and UKE-1 carry JAK2V617F and derive from patients with MPD/MDS histories. Challenging the consensus that expression of JAK2V617F is the sole precondition for cytokine independence in class I cytokine receptor-positive cells, two of four of the JAK2mu cell lines were growth factor-dependent. These cell lines resembled JAK2wt cells regarding JAK2/STAT5 activation: cytokine deprivation effected dephosphorylation, whereas erythropoetin or granulocyte colony-stimulating factor induced phosphorylation of JAK2 and STAT5. Cytokine independence correlated with low expression and cytokine dependence with high expression of the JAK/STAT pathway inhibitor suppressor of cytokine signaling 2 (SOCS2) suggesting a two-step mechanism for cytokine independence of MPD cells: (i) activation of the oncogene JAK2V617F and (ii) inactivation of the tumor suppressor gene SOCS2. Confirming that SOCS2 operates as a negative JAK2V617F regulator, SOCS2 knockdown induced constitutive STAT5 phosphorylation in JAK2mu cells. CpG island hypermethylation is reported to promote SOCS gene silencing in malignant diseases. Accordingly, in one of two cytokine-independent cell lines and in two of seven MPD patients, we found SOCS2 hypermethylation associated with reduced promoter access to transcription factors. Our results provide solid evidence that SOCS2 epigenetic downregulation might be an important second step in the genesis of cytokine-independent MPD clones.

JAK2 V617F tyrosine kinase mutation in cell lines derived from myeloproliferative disorders

A mutation in the JH2 pseudokinase domain of the Janus kinase 2 gene (JAK2 V617F) has been described in chronic myeloproliferative disorders (MPD). We screened 79 acute myeloid leukemia (AML) cell lines and found five positive for JAK2 V617F (HEL, MB-02, MUTZ-8, SET-2, UKE-1), 4/5 with histories of MPD/MDS. While SET-2 expressed both mutant (mu) and wild-type (wt) JAK2, remaining positives carried homo-/hemizygous JAK2 mutations. Microsatellite analysis confirmed losses of heterozygosity (LOH) affecting the JAK2 region on chromosome 9p in MB-02, MUTZ-8 and UKE-1, but also in HEL, the only JAK2mu cell line lacking any reported MPD/MDS history. All five JAK2mu cell lines displayed cytogenetic hallmarks of MDS, namely losses of 5q or 7q, remarkably in 4/5 cases affecting both chromosomes. Our combined FISH and microsatellite analysis uncovered a novel mechanism to supplement mitotic recombination previously proposed to explain JAK2 LOH, namely chromosome deletion with/without selective JAK2mu amplification. Confirming the importance of the mutated JAK2 protein for growth and prevention of apoptosis, JAK2mu cell lines displayed higher sensitivities to JAK2 inhibition than JAK2wt cell lines. In summary, JAK2 V617F cell lines, derived from patients with history of MPD/MDS, represent novel research tools for elucidating the pathobiology of this JAK2 mutation.