In vitro culture studies of childhood myelodysplastic syndrome: establishment of the cell line MUTZ-1

Genome-wide CRISPR screening identifies critical role of phosphatase and tensin homologous (PTEN) in sensitivity of acute myeloid leukemia to chemotherapy

Although significant progress has been made in the development of novel targeted drugs for the treatment of acute myeloid leukemia (AML) in recent years, chemotherapy still remains the mainstay of treatment and the overall survival is poor in most patients. Here, we demonstrated the antileukemia activity of a novel small molecular compound NL101, which is formed through the modification on bendamustine with a suberanilohydroxamic acid (SAHA) radical. NL101 suppresses the proliferation of myeloid malignancy cells and primary AML cells. It induces DNA damage and caspase 3-mediated apoptosis. A genome-wide clustered regularly interspaced short palindromic repeats (CRISPR) library screen revealed that phosphatase and tensin homologous (PTEN) gene is critical for the regulation of cell survival upon NL101 treatment. The knockout or inhibition of PTEN significantly reduced NL101-induced apoptosis in AML and myelodysplastic syndrome (MDS) cells, accompanied by the activation of protein kinase B (AKT) signaling pathway. The inhibition of mammalian target of rapamycin (mTOR) by rapamycin enhanced the sensitivity of AML cells to NL101-induced cell death. These findings uncover PTEN protein expression as a major determinant of chemosensitivity to NL101 and provide a novel strategy to treat AML with the combination of NL101 and rapamycin.

A research review of experimental animal models with myelodysplastic syndrome

Myelodysplastic syndrome (MDS) consists of a group of hematologic tumors that are derived from the clonal proliferation of hematopoietic stem cells, featuring abnormal hematopoietic cell development and ineffective hematopoiesis. Animal models are an important scientific research platform that has been widely applied in the research of human diseases, especially tumors. Animal models with MDS can simulate characteristic human genetic variations and tumor phenotypes. They also provide a reliable platform for the exploration of the pathogenesis and diagnostic markers of MDS as well as for a drug efficacy evaluation. This paper reviews the research status of three animal models and a new spontaneous mouse model with MDS.

Deferasirox combination with eltrombopag shows anti-myelodysplastic syndrome effects by enhancing iron deprivation-related apoptosis

Iron overload (IO) affected the survival of patients with myelodysplastic syndrome (MDS). Deferasirox (DFX) is widely used in patients with MDS for iron chelation therapy, but is not suitable for MDS patients with severe thrombocytopenia. Eltrombopag (ELT) is a type of thrombopoietin receptor (TPOR) analog used in the treatment of thrombocytopenia. Therefore, we sought to explore the synergistic effects and possible mechanisms of DFX combination with ELT in MDS cells. In our study, the combination of DFX with ELT synergistically inhibited proliferation, induced apoptosis and arrested cell cycle of MDS cells. Through the RNA-sequence and gene set enrichment analysis (GSEA), iron metabolism-related pathway played important roles in apoptosis of SKM-1 cells treated with DFX plus ELT. Transferrin receptor (TFRC) was significantly highly expressed in combination group than that in single agent groups, without affecting TPOR. Furthermore, the apoptosis of the combination group MDS cells could be partially reversed by ferric ammonium citrate (FAC), accompanied with decreased expression of TFRC. These results suggested that the combination of DFX and ELT synergistically induced apoptosis of MDS cells by enhancing iron deprivation-related pathway.

Summary of animal models of myelodysplastic syndrome

Myelodysplastic syndrome (MDS) is a malignant tumor of the hematological system characterized by long-term, progressive refractory hemocytopenia. In addition, the risk of leukemia is high, and once it develops, the course of acute leukemia is short with poor curative effect. Animal models are powerful tools for studying human diseases and are highly effective preclinical platforms. Animal models of MDS can accurately show genetic aberrations and hematopoietic clone phenotypes with similar cellular features (such as impaired differentiation and increased apoptosis), and symptoms can be used to assess existing treatments. Animal models are also helpful for understanding the pathogenesis of MDS and its relationship with acute leukemia, which helps with the identification of candidate genes related to the MDS phenotype. This review summarizes the current status of animal models used to research myelodysplastic syndrome (MDS).

Abnormal Ferroptosis in Myelodysplastic Syndrome

Background

Ferroptosis is a form of iron-dependent non-apoptotic cell death, with characteristics of loss of the activity of the lipid repair enzyme, glutathione (GSH) peroxidase 4 (GPX4), and accumulation of lethal reactive lipid oxygen species. The mechanism of ferroptosis in myelodysplastic syndrome (MDS) is unclear.

Methods

Cell viability assay, reactive oxygen species (ROS) assay, GSH assay, and GPX activity assay were performed to study the regulation of ferroptosis in MDS cells obtained from MDS patients, the iron overload model mice, and cell lines.

Results

The growth-inhibitory effect of decitabine could be partially reversed by ferrostatin-1 and iron-chelating agent [desferrioxamine (DFO)] in MDS cell lines. Erastin could increase the cytotoxicity of decitabine on MDS cells. The level of GSH and the activity of GPX4 decreased, whereas the ROS level increased in MDS cells upon treatment with decitabine, which could be reversed by ferrostatin-1. The concentration of hemoglobin in peripheral blood of iron overload mice was negatively correlated with intracellular Fe²⁺ level and ferritin concentration. Iron overload (IO) led to decreased viability of bone marrow mononuclear cells (BMMNCs), which was negatively correlated with intracellular Fe²⁺ level. Ferrostatin-1 partially reversed the decline of cell viability in IO groups. The level of GSH and the activity of GPX4 decreased, whereas the ROS level increased in BMMNCs of IO mice. DFO could increase the level of GSH. Ferrostatin-1 and DFO could increase the GPX4 activity of BMMNCs in IO mice. Ferrostatin-1 could significantly reverse the growth-inhibitory effect of decitabine in MDS patients. Decitabine could significantly increase the ROS level in MDS groups, which could be inhibited by ferrostatin-1 or promoted by erastin. Ferrostatin-1 could significantly reverse the inhibitory effect of decitabine on GSH levels in MDS patients. Erastin combined with decitabine could further reduce the GSH level. Erastin could further decrease the activity of GPX4 compared with the decitabine group.

Conclusion

Ferroptosis may account for the main mechanisms of how decitabine induced death of MDS cells. Decitabine-induced ROS raise leads to ferroptosis in MDS cells by decreasing GSH level and GPX4 activity.

Sonic hedgehog signaling pathway in Myelodysplastic Syndrome: Abnormal activation and jervine intervention

OBJECTIVE

This study aims to investigate the roles of Sonic hedgehog (Shh) signaling pathway in the occurrence and progression of Myelodysplastic Syndrome (MDS) and further evaluate using jervine as therapeutic strategy for MDS by inhibiting Shh pathway.

METHODS

CD34+ cells from the bone marrow of 53 MDS patients were counted by flow cytometry and isolated by magnetic bead sorting. Shh, Smo, Ptch-1 and Gli-1 (involved in Shh pathway) in CD34+ cells were examined by RT-qPCR. Besides, the relationship between Shh pathway-related genes and the clinical features or prognosis of MDS were analyzed. Further, the effects of jervine on MUTZ-1 cells regarding their proliferation, apoptosis and cell cycle as well as Shh pathway-related gene and protein expression were analyzed.

RESULTS

Gene expression level of Shh, Gli-1 and Smo was significantly increased in MDS patients. Herein, Smo and Gli-1 were correlated with chromosome karyotype classification and IPSS. MDS patients with high expression of Smo or Gli-1 had a poor prognosis. Jervine inhibited gene and protein expression of Shh, Smo, Ptch-1 and Gli-1. Besides, jervine suppressed the proliferation and promoted the apoptosis of MUTZ-1 cells, as well as inhibited the transition of cells from G1 to S phase.

CONCLUSION

Shh signaling pathway of MDS patients is abnormally activated and participated in the occurrence and progression of MDS. Jervine intervention is a potential therapeutic strategy for MDS.

Decitabine shows synergistic effects with arsenic trioxide against myelodysplastic syndrome cells via endoplasmic reticulum stress-related apoptosis

Most of the International Prognostic Scoring System (IPSS) high-risk patients with myelodysplastic syndrome partly responded to hypomethylating therapy even with transient remission, while arsenic trioxide (ATO) had partial effect in patients with MDS. Therefore, we sought to investigate the effects and possible mechanisms of the combination of ATO and decitabine (DAC) in MDS cells. In our study, the MUTZ-1 and SKM-1 cells were treated with ATO, DAC or both. Cell viability, cell apoptosis, levels of reactive oxygen species (ROS) and expressions of the endoplasmicreticulum (ER) stress-associated genes and proteins were examined. Results showed the combination of ATO and DAC synergistically inhibited the proliferation and induced apoptosis of MDS cells. Through the RNA-sequence and GSEA gene function analysis, ER stress-related pathway played an important role in apoptosis of MDS cells induced by the combination of ATO and DAC. ER stress-related genes DNA damage inducible transcript 3, GRP78, and activating transcription factor-6 were significantly highly expressed in combination group than those in single agent groups; proteins were confirmed by western blot. The levels of ROS significantly increased in the combination group. Furthermore, the apoptosis of (ATO+DAC) group MDS cells could be partially reversed by antioxidant agent N-acetylcysteine, accompanied by decreased expression of intracellular ROS and ER stress-related genes. These results suggested that the combination of ATO and DAC synergistically induced the apoptosis of MDS cells by increased ROS-related ER stress in MDS cells.

A novel histone deacetylase inhibitor Chidamide induces G0/G1 arrest and apoptosis in myelodysplastic syndromes

Chidamide as a newly designed and synthesized histone deacetylase inhibitor induces an antitumor effect in various cancer, and it has been used in several clinical trials such as peripheral T cell lymphoma (PTCL). Here we demonstrate that Chidamide was able to increase the acetylation levels of histone H3 and decrease HDAC activity in MDS cell lines(SKM-1,MUTZ-1)and AML cell line(KG-1). In vitro, at low concentration (<250nM) of Chidamide inhibited cell proliferation and delayed G0/G1 cell cycle progression by down-regulating CDK2 and regulating p-P53 and P21 protein expression. Meanwhile,it also induced cell apoptosis by down-regulating Bcl-2 and up-regulating cleaved Caspase-3 and Bax protein expression.The results of the present study demonstrates the potential utility of Chidamide for the treatment of Myelodysplastic syndromes.

Targeting the Sonic Hedgehog-Gli1 Pathway as a Potential New Therapeutic Strategy for Myelodysplastic Syndromes

The complex mechanistic array underlying the pathogenesis of myelodysplastic syndrome (MDS) is still unclear. Although dysregulations of different signaling pathways involved in MDS have been described, the identification of specific biomarkers and therapy targets remains an important task in order to establish novel therapeutic approaches. Here, we demonstrated that the Shh signaling pathway is active in MDS and correlated it with disease progression. Additionally, the knockdown of Gli1 significantly inhibited cell proliferation in vitro and in vivo. Gli1 silencing also induced apoptosis and G0/G1 phase arrest. Furthermore, Gli1 silencing enhanced the demethylating effect of 5-aza-2'-deoxycytidine on the p15 gene promoter and subsequently promoted its expression by inhibiting DNA methyltransferase 1(DNMT1). Our findings show that the Shh signaling pathway plays a role in the pathogenesis and disease progression of MDS, and proceeds by modulating DNA methylation. This pathway may prove to be a potential therapeutic target for enhancing the therapeutic effects of 5-azacytidine on malignant transformation of MDS.

Sonic hedgehog produced by bone marrow-derived mesenchymal stromal cells supports cell survival in myelodysplastic syndrome

The role of marrow microenvironment in the pathogenesis of myelodysplastic syndrome (MDS) remains controversial. Therefore, we studied the influence of bone marrow-derived mesenchymal stromal cells (BMSCs) from patients with different risk types of MDS on the survival of the MDS cell lines SKM-1 and MUTZ-1. We first demonstrated that the expression of Sonic hedgehog (Shh), smoothened (Smo), and glioma-associated oncogene homolog 1 (Gli1) was increased in MDS patients (n = 23); the increase in expression was positively correlated with the presence of high-risk factors. The Shh signaling inhibitor, cyclopamine, inhibited high-risk MDS BMSC-induced survival of SKM-1 and MUTZ-1 cells, suggesting a role for Shh signaling in MDS cell survival. Furthermore, cyclopamine-mediated inhibition of Shh signaling in SKM-1 and MUTZ-1 cells resulted in decreased DNMT1 expression and cell survival; however, exogenous Shh peptide had the opposite effect, suggesting that Shh signaling could regulate the expression of DNMT1, thereby modulating cell survival in MDS. In addition, the apoptosis of SKM-1 and MUTZ-1 cell increased significantly when cultured with cyclopamine and a demethylation agent, 5-Aza-2′-deoxycytidine. These findings suggest that Shh signaling from BMSCs is important in the pathogenesis of MDS and could play a role in disease progression by modulating methylation.

Downregulation of hTERT: an important As2O3 induced mechanism of apoptosis in myelodysplastic syndrome

Two myelodysplastic syndrome (MDS) celllines, MUTZ-1 and SKM-1 cells, were used to study the effect of arsenic trioxide (As₂O₃) on hematological malignant cells. As₂O₃ induced this two cell lines apoptosis via activation of caspase-3/8 and cleavage of poly (ADP-ribose) polymerase (PARP), a DNA repair enzyme. As₂O₃ reduced NF-κB activity, which was important for inducing MUTZ-1 and SKM-1 cells apoptosis. As₂O₃ also inhibited the activities of hTERT in MUTZ-1 and SKM-1 cells. Moreover, the NF-κB inhibitor, pyrrolidine dithiocarbamate (PDTC), had no effect on caspase-8 activation, although PDTC did inhibit MUTZ-1 and SKM-1 cells proliferation. Incubation of MUTZ-1 cells with a caspase-8 inhibitor failed to block As₂O₃-induced inhibition of NF-κB activity. Our findings suggest that As₂O₃ may induce apoptosis in MUTZ-1 and SKM-1 cells by two independent pathways: first, by activation of caspase-3/8 and PARP; and second, by inhibition of NF-κB activity, which results in downregulation of hTERT expression. We conclude that hTERT and NF-κB are important molecular targets in As₂O₃-induced apoptosis.

Reversal of bortezomib resistance in myelodysplastic syndrome cells by MAPK inhibitors

The myelodysplastic syndromes (MDS) comprise a heterogeneous group of malignant neoplasms with distinctive clinicopathological features. Currently, there is no specific approach for the treatment of MDS. Here, we report that bortezomib (BTZ), a proteasome inhibitor that has been used to treat plasma cell myeloma, induced G2/M phase cycle arrest in the MDS cell line SKM-1 through upregulation of Wee1, a negative regulator of G2/M phase transition. Treatment by BTZ led to reduced SKM-1 cell viability as well as increased apoptosis and autophagy. The BTZ-induced cell death was associated with reduced expression of p-ERK. To elucidate the implications of downregulation of p-ERK, we established the BTZ resistant cell line SKM-1R. Our data show that resistance to BTZ-induced apoptosis could be reversed by the MEK inhibitors U0126 or PD98059. Our results suggest that MAPK pathway may play an important role in mediating BTZ resistance.

Antitumor activity and drug interactions of proteasome inhibitor Bortezomib in human high-risk myelodysplastic syndrome cells

The purpose of this study was to investigate the antitumor effects and drug interactions of the proteasome inhibitor Bortezomib against high-risk myelodysplastic syndrome (MDS) cells in vitro and in vivo. The high-risk MDS-derived MUTZ-1 cell line and bone marrow mononuclear cells from primary high-risk MDS patients were used to examine antitumor activity and drug interactions for Bortezomib. Apoptotic proteins, including caspase and Bcl-2 family members, as well as the protein FLIP, were studied. Phosphoinositide 3-kinase (PI3K)/Akt and MAPK signaling pathways were also examined. The PI3K inhibitor LY294002 was used to examine the involvement of the PI3K/Akt signaling pathway in the induction of apoptosis. Cytarabine (AraC) and daunorubicin (DNR) were used to test for synergistic effects between Bortezomib and chemotherapeutic agents. SCID mice xenografted with MUTZ-1 cells were used for in vivo study. We found that Bortezomib could induce growth arrest and apoptosis in high-risk MDS cells in vitro and in vivo. The mechanisms were related to decreased activation of the PI3K/Akt survival signaling pathway, but not the MAPK pathway, and involved inhibition of the NF-κB activity and downregulation of the Bcl-2/Bax and FLIPL/FLIPS ratios, triggering the activation of caspase cascades. This phenomenon was inhibited by the PI3K inhibitor LY294002. Bortezomib also acted synergistically with the chemotherapeutic agents AraC and DNR, which are associated with the inhibition of NF-κB activity. Our results demonstrate that Bortezomib can induce growth arrest and apoptosis of high-risk MDS cells and had a synergistic effect with two chemotherapeutic agents. Our findings provide new insights for the treatment of high-risk MDS, using either Bortezomib alone, or in combination with conventional antineoplastic agents.

Mouse models of myelodysplastic syndromes

Three general approaches have been used to model myelodysplastic syndrome (MDS) in mice, including treatment with mutagens or carcinogens, xenotransplantation of human MDS cells, and genetic engineering of mouse hematopoietic cells. This article discusses the phenotypes observed in available mouse models for MDS with a concentration on a model that leads to aberrant expression of conserved homeobox genes that are important regulators of normal hematopoiesis. Using these models of MDS should allow a more complete understanding of the disease process and provide a platform for preclinical testing of therapeutic approaches.

NUP98-HOX translocations lead to myelodysplastic syndrome in mice and men

The myelodysplastic syndromes (MDS) are a group of clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis, peripheral blood cytopenias, dysplasia, and a propensity for transformation to acute myeloid leukemia (AML). A wide spectrum of genetic aberrations has been associated with MDS, including chromosomal translocations involving the NUP98 gene, most commonly leading to fusions of NUP98 with abd-b group HOX genes, including HOXD13. We used vav regulatory elements to direct expression of a NUP98-HOXD13 (NHD13) fusion gene in hematopoietic tissues. NHD13 transgenic mice faithfully recapitulate all the key features of MDS, including peripheral blood cytopenias, bone marrow dysplasia and apoptosis, and transformation to acute leukemia. The MDS that develops in NHD13 transgenic mice is highly lethal; within 14 months, 90% of the mice died of either leukemic transformation or severe anemia and leukopenia due to progressive MDS. These mice provide a preclinical model that can be used for the evaluation of MDS therapy and biology.

Human urine extract CDA-2 induces apoptosis of myelodysplastic syndrome-derived MUTZ-1 cells through the PI3K/Akt signaling pathway in a caspase-3-dependent manner

AIM

The aim of this study was to investigate the antitumoral activity of human urine extract against myelodysplastic syndrome (MDS)-derived MUTZ-1 cells in vitro and in vivo.

METHODS

The MDS-refractory anemia with excess of blasts (RAEB)-derived MUTZ-1 cell line was used to examine the effects of a human urine preparation, CDA-2, on the induction of growth arrest and apoptosis. Apoptotic proteins, including caspase family, Bcl-2 family, the inhibitor of apoptosis protein (IAP) family, and the FLICE-like inhibitory protein (FLIP), as well as cell cycle-associated proteins were studied. The phosphoinositide 3 kinase (PI3K)/Akt survival signaling pathway and the NF-kappaB pathway were also examined. The caspase-3 inhibitor Z-DEVD-fmk was used to examine the involvement of caspase-3 and poly (ADP-ribose) polymerase (PARP). PI3K inhibitor LY294002 was used to examine the involvement of the PI3K/Akt signaling pathway in this apoptosis-inducing effect. MUTZ-1 cell xenografted serious combined immunodeficiency disease mice were used for the in vivo study.

RESULTS

We found that CDA-2 could induce growth arrest and apoptosis of MUTZ-1 cells in vitro and in vivo. The main mechanisms were related to the inhibition of PI3Kp110alpha expression at the transcriptional level, which inactivated the phosphorylation of Akt involving the prevention NF-kappaB phosphorylation and nuclear translocation, the downregulation of the IAP family and FLIPL protein, and the dephosphorylation of the Bad protein, which then triggered the activation of the caspase cascades. This phenomenon could be inhibited by the PI3K inhibitor LY294002 and caspase-3 inhibitor Z-DEVD-fmk.

CONCLUSION

Our results demonstrate the presence of active components in the human urine extract that can induce the growth arrest and apoptosis of MDS-RAEB-derived MUTZ-1 cells and may involve the PI3K/Akt signaling pathway in a caspase-3-dependent manner. This may provide new insights for the treatment of high-risk MDS.

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

The advent of continuous human leukemia-lymphoma cell lines as a rich resource of abundant, accessible and manipulable living cells has contributed significantly to a better understanding of the pathophysiology of hematopoietic tumors. We describe the establishment of the new continuous leukemia cell line MUTZ-8 from a patient with acute myeloid leukemia (AML): MUTZ-8 was derived from the peripheral blood of a 63-year-old woman with AML M4 (25 years after onset of myelodysplastic syndromes, MDS). DNA fingerprinting confirmed authenticity and derivation of the cell line. The immunoprofiling as determined by flow cytometry showed that MUTZ-8 is positive mainly for myeloid but also some monocytic and megakaryocytic markers, whereas it is negative for T cell, B cell and erythroid markers. The cell line is constitutively cytokine-dependent, proliferation requiring externally added cytokines. The cytokine response profiles showed a two- to 10-fold growth stimulation of the cells by various cytokines, whereas other cytokines led to growth inhibition. Cytogenetic analysis confirmed the common clonal derivation of the cell line and the malignant clone predominating at the times of sampling. MUTZ-8 displays a deletion of the 5q31 AML/MDS region effected by a non-reciprocal translocation, t(5;11)(q21;q10). The scientific utility of MUTZ-8 lies (1) in its cluster of pathognomonic cytogenetic alterations including a 5q31 breakpoint and (2) in its absolute cytokine dependency and proliferative response to various cytokines.

A novel nuclear protein, 5qNCA (LOC51780) is a candidate for the myeloid leukemia tumor suppressor gene on chromosome 5 band q31

Interstitial deletion or loss of chromosome 5, del(5q) or -5, is a frequent finding in myeloid leukemias and myelodysplasias, suggesting the presence of a tumor suppressor gene within the deleted region. In our search for this gene, we identified a candidate, 5qNCA (LOC51780), which lies within a consistently-deleted segment of 5q31. 5qNCA expresses a 7.2-kb transcript with a 5286-bp open reading frame which is present at high levels in heart, skeletal muscle, kidney, placenta, and liver as well as CD34+ cells and AML cell lines. 5qNCA encodes a 191-kD nuclear protein which contains a highly-conserved C-terminus containing a zinc finger with the unique spacing Cys-X2-Cys-X7-His-X2-Cys-X2-Cys-X4-Cys-X2-Cys and a jmjC domain, which is often found in proteins that regulate chromatin remodeling. Expression of 5qNCA in a del(5q) cell line results in suppression of clonogenic growth. Preliminary sequence results in AML and MDS samples and cell lines has revealed a possible mutation in the KG-1 cell line resulting in a THR to ALA substitution that has not been found in over 100 normal alleles to date. We propose 5qNCA is a good candidate for the del(5q) tumor suppressor gene based on its predicted function and growth suppressive activities, and suggest that further mutational and functional study of this interesting gene is warranted.

Human mortalin (HSPA9): a candidate for the myeloid leukemia tumor suppressor gene on 5q31

Human mortalin (HSPA9) was originally identified by its close homology to murine mortalins, which play important roles in cellular senescence. The two murine genes, mot-1 and mot-2, differ in only two amino acid residues, but have opposite functions in cellular immortalization. HSPA9 was recently localized to chromosome 5, band q31, a region that is frequently deleted in myeloid leukemias and myelodysplasia (MDS), making it a candidate tumor suppressor gene, which is consistent with the biological function of its murine homologue. To evaluate mortalin in this capacity, its expression in normal and leukemic cell lines was investigated, and its genomic structure was determined in order to facilitate mutation detection. RT-PCR and Northern blot analysis revealed a broad distribution in normal tissues and in leukemia cell lines, producing a single 2.8 kb transcript. Genomic characterization showed that the gene spans 18 kb, and consisted of 17 exons with boundaries that were almost identical to its murine counterpart. Using intron-based primers to flank each exon, sequence of the complete protein-coding regions was obtained for three AML cell lines, including two lines with chromosome 5 loss (KG-1 and HL-60) and one without (AML-193) compared to normal DNA. No mutations were identified although one conservative nucleotide sequence variant was observed in exon 16. We have shown that mortalin is highly conserved in genomic structure as well as sequence, and the designed primers will be suitable for future studies to detect mutations in clinical samples.

Establishment of a myelodysplastic syndrome (MDS)/secondary AML-derived T lymphoid cell line K2-MDS

We have established a T lymphoid cell line, K2-MDS, from the peripheral blood mononuclear cells (PBMC) of a patient with acute myeloblastic leukemia (AML) transformed myelodysplastic syndrome (MDS). K2-MDS cells are positive for the expression of CD4, CD5, CD13, CD25, CD71, CD95, HLA-DR and cytoplasmic CD3. Southern blotting analysis shows T cell receptor (TCR) beta chain genes rearrangements, whereas immunoglobulin heavy chain (IgH) genes are not rearranged. Further, the patient PBMC contains TCR beta chain genes rearrangements in the same manner as K2-MDS cells. The data indicate that K2-MDS is a T lymphoid cell line derived from a myelodysplastic clone in the patient PBMC. This new MDS-derived cell line K2-MDS may be a useful in vitro model for studies on the pathogenetic mechanisms leading to MDS.

Malignant hematopoietic cell lines: in vitro models for the study of myelodysplastic syndromes

The myelodysplastic syndromes (MDS) are clonal myeloid disorders characterized by bone marrow cell dysplasia and ineffective hematopoiesis leading to peripheral refractory cytopenias. The course of the disease ranges from a chronic status with progressively impaired hematopoiesis to rapid evolution to acute myeloid leukemia (AML). A panel of continuous malignant hematopoietic cell lines has been established from the whole spectrum of MDS variants and also from the different stages of the diseases, namely from the MDS phase or the overt leukemia post-MDS phase. Ten cell lines were derived from the various MDS subtypes; 17 cell lines were established from patients with leukemia (mainly AML) post-MDS. While most cell lines display myelocytic, monocytic or erythroid features, some cell lines carry lymphoid characteristics (precursor B-cell, B-cell, or T-cell), With regard to these lymphoid MDS-derived cell lines, more detailed authentication (prove of derivation from the assumed patient) and verification (prove of the malignant nature of the cell line and derivation from the assumed neoplastic cells) are required to validate the cell lines as true in vitro representatives of MDS and to exclude any cross-contamination with other cells or immortalization of normal bystander cells. On the other hand, lymphoid MDS-derived cell lines may attest to the clonal nature of MDS which may afflict progenitor cells giving rise to lymphoid or myelomonocytoid cells. Many of the MDS-derived cell lines carry cytogenetic and molecular genetic abnormalities typically associated with MDS: gain or loss of all or parts of chromosomes 5, 7, 8 and 20 (-5/5q-, -7/7q-, + 8, 20q-); alterations of oncogenes and tumor suppressor genes (IRF-1, p15, p16, p53, RAS, RB). In summary, the present panel of cell lines provides continuously growing cells and thus unlimited cell material for use as in vitro paradigms covering the whole spectrum of MDS-related hematopoetic malignancies. Properly authenticated and verified MDS-derived cell lines which should be made freely available will represent important research tools for the study of MDS biology.

Establishment and characterization of human B cell precursor-leukemia cell lines

A large number of continuous human leukemia cell lines have been established over the last three decades. Clearly, leukemia cell lines have become important research tools. Here, we have summarized the immunological, molecular and standard cytogenetic features of a panel of well characterized B cell precursor (BCP)-leukemia cell lines which were derived from patients with acute lymphoblastic/undifferentiated leukemia (ALL/AUL) or chronic myeloid leukemia (CML) in blast crisis. Following the recently proposed immunological EGIL classification, we assigned our panel of 27 BCP-cell lines to one of the following categories: B-I pro-B cell line; B-II common-B cell line; and B-III pre-B cell line. All cell lines express general B-lineage associated surface markers (HLA-DR, CD22, CD79a) being negative for surface immunoglobulin (Ig); the differences between the subgroups reside in expression of CD10 and cytoplasmic Ig. Several BCP-cell lines show the myelomonocytic cell-associated markers CD13 and/or CD33. These immunologically 'biphenotypic' BCP-cell lines are generally TdT+ CD10+ CD13+ CD19+ CD22+ CD34+ and carry the Philadelphia (Ph) translocation. The BCP-cell lines display surface receptors for interferon-gamma (CD119), interleukin-7 (CD127) and FLT-3 ligand (CD135). All BCP-cell lines examined have complex numerical and structural chromosomal alterations including translocations commonly seen in BCP-ALL such as t(4;11), t(9;22), t(11;19), t(12;21), and t(17;19) involving the fusion genes MLL-AF4, BCR-ABL, ENL-MLL, TEL/ETV6-AML1 and E2A-HLF, respectively. Besides the expected rearrangement of the Ig heavy chain receptor gene, several cell lines also have rearrangements of the T cell receptor genes beta, gamma or delta. While some BCP-cell lines express (aberrantly) myeloperoxidase at the mRNA level, most lines are negative in the immunological or cytochemical staining. Several large series documented the difficulty in establishing such BCP cell lines with success rates in the range of 10-20% (on average 15%). Still, since the establishment of the first bonafide BCP-cell line in 1974 (cell line REH), some 150 cell lines have been established of which, however, only a small percentage have been sufficiently well characterized and described. A higher success rate for immortalizing any given leukemia cell might depend on a closer emulation of the physiological in vivo microenvironment. The possibility to grow in vitro leukemia cells at will would represent ideal experimental systems permitting basic research and patient-specific investigations. In summary, the use of well-characterized BCP-cell lines provide unprecedented opportunities for studying a multitude of biological aspects related to normal and neoplastic B-lymphocytes.