miR-29c&b2 encourage extramedullary infiltration resulting in the poor prognosis of acute myeloid leukemia.

Extramedullary infiltration (EMI), as a concomitant symptom of acute myeloid leukemia (AML), is associated with low complete remission and poor prognosis in AML. However, the mechanism of EMI remains indistinct. Clinical trials showed that increased miR-29s were associated with a poor overall survival in AML [14]. Nevertheless, they were proved to work as tumor suppressor genes by encouraging apoptosis and inhibiting proliferation in vitro. These contradictory results led us to the hypothesis that miR-29s may play a notable role in the prognosis of AML rather than leukemogenesis. Thus, we explored the specimens of AML patients and addressed this issue into miR-29c&b2 knockout mice. As a result, a poor overall survival and invasive blast cells were observed in high miR-29c&b2-expression patients, and the wildtype mice presented a shorter survival with heavier leukemia infiltration in extramedullary organs. Subsequently, we found that the miR-29c&b2 inside leukemia cells promoted EMI, but not the one in the microenvironment. The analysis of signal pathway revealed that miR-29c&b2 could target HMG-box transcription factor 1 (Hbp1) directly, then reduced Hbp1 bound to the promoter of non-muscle myosin IIB (Myh10) as a transcript inhibitor. Thus, increased Myh10 encouraged the migration of leukemia cells. Accordingly, AML patients with EMI were confirmed to have high miR-29c&b2 and MYH10 with low HBP1. Therefore, we identify that miR-29c&b2 contribute to the poor prognosis of AML patients by promoting EMI, and related genes analyses are prospectively feasible in assessment of AML outcome.

Differentiation syndrome during ivosidenib treatment with immunohistochemistry showing isocitrate dehydrogenase R132H mutation.

We report a case of differentiation syndrome in a patient receiving the IDH1 inhibitor ivosidenib, with skin biopsy showing isocitrate dehydrogenase (IDH) R132H-mutated leukemia cutis. A 72-year-old man with IDH1-mutated acute myeloid leukemia (AML), status-post allogeneic cell transplantation, on ivosidenib for 6 months, was admitted for culture-negative neutropenic fever, pink and purpuric plaques and patches on the legs, abdomen and back, edema, hypotension, and shortness of breath. Skin biopsy revealed an infiltrate of atypical, immature, myeloperoxidase-positive mononuclear cells compatible with leukemia cutis or Sweet syndrome. Although dermal edema and interstitial neutrophilic infiltrate with karyorrhexis characteristic of Sweet syndrome were not seen, the atypical cells lacked expression of CD117 and CD34, which were expressed in the original leukemia. Additional immunohistochemical staining of suspected blasts was strongly positive for IDH1 R132H, suggesting a diagnosis of leukemia cutis. As the immunophenotype of blasts in skin infiltrates can significantly differ from the immunophenotype seen in blood and bone marrow, this case shows that mutation-specific antibodies such as anti-IDH1 R132H may be useful to help distinguish malignant from non-malignant infiltrates in the skin. Furthermore, differentiation syndrome may show histopathologic features of leukemia cutis on skin biopsy.

Leukemic marrow infiltration reveals a novel role for Egr3 as a potent inhibitor of normal hematopoietic stem cell proliferation.

Cytopenias resulting from the impaired generation of normal blood cells from hematopoietic precursors are important contributors to morbidity and mortality in patients with leukemia. However, the process by which normal hematopoietic cells are overtaken by emerging leukemia cells and how different subsets of hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) are distinctly influenced during leukemic cell infiltration is poorly understood. To investigate these important questions, we used a robust nonirradiated mouse model of human MLL-AF9 leukemia to examine the suppression of HSCs and HPCs during leukemia cell expansion in vivo. Among all the hematopoietic subsets, long-term repopulating HSCs were the least reduced, whereas megakaryocytic-erythroid progenitors were the most significantly suppressed. Notably, nearly all of the HSCs were forced into a noncycling state in leukemic marrow at late stages, but their reconstitution potential appeared to be intact upon transplantation into nonleukemic hosts. Gene expression profiling and further functional validation revealed that Egr3 was a strong limiting factor for the proliferative potential of HSCs. Therefore, this study provides not only a molecular basis for the more tightened quiescence of HSCs in leukemia, but also a novel approach for defining functional regulators of HSCs in disease.

Development and function of human innate immune cells in a humanized mouse model.

Mice repopulated with human hematopoietic cells are a powerful tool for the study of human hematopoiesis and immune function in vivo. However, existing humanized mouse models cannot support development of human innate immune cells, including myeloid cells and natural killer (NK) cells. Here we describe two mouse strains called MITRG and MISTRG, in which human versions of four genes encoding cytokines important for innate immune cell development are knocked into their respective mouse loci. The human cytokines support the development and function of monocytes, macrophages and NK cells derived from human fetal liver or adult CD34(+) progenitor cells injected into the mice. Human macrophages infiltrated a human tumor xenograft in MITRG and MISTRG mice in a manner resembling that observed in tumors obtained from human patients. This humanized mouse model may be used to model the human immune system in scenarios of health and pathology, and may enable evaluation of therapeutic candidates in an in vivo setting relevant to human physiology.

Bone marrow histopathology in the diagnostic evaluation of splenic marginal-zone and splenic diffuse red pulp small B-cell lymphoma: a reliable substitute for spleen histopathology?

Primary splenic small B-cell lymphomas mostly comprise the distinct entity of splenic marginal-zone lymphoma (SMZL) and the provisional category of splenic lymphoma/leukemia unclassifiable, mainly represented by the hairy cell leukemia variant and splenic diffuse red pulp small B-cell lymphoma (SDRL). Until recently, histopathologic examination of splenectomy specimens was considered mandatory for the diagnosis of SMZL. However, nowadays, mainly because of advances in chemoimmunotherapy, splenectomy is performed much less frequently. We evaluated the diagnostic efficacy of bone marrow biopsy (BMB) histopathology in the diagnostic approach toward SMZL and SDRL and tested whether it may serve as a substitute for spleen histopathology in the differential diagnosis between these 2 entities. To this end, we conducted a paired assessment of BMB and spleen diagnostic samples from 46 cases with a diagnosis of SMZL (n=32) or SDRL (n=14) based on spleen histopathology. We demonstrate that detailed immunohistopathologic BMB evaluation offers adequate evidence for the confirmation of these entities and their differential diagnosis from other small B-cell lymphoma histotypes. Notably, the immunophenotypical profile of SMZL and SDRL was identical in both BMB and spleen specimens for 21 evaluated markers. Paired assessment of BMB and spleen specimens did not identify discriminating patterns of BMB infiltration, cytology, and/or immunohistology between SMZL and SDRL. Accordingly, bone marrow histopathology contributes significantly in confirming the diagnosis of SMZL and SDRL. However, presently it is not possible to distinguish SMZL from SDRL on the basis of BMB evaluation alone; hence, histopathologic examination of the spleen remains the "gold standard" approach.

ALK+ALCLs induce cutaneous, HMGB-1-dependent IL-8/CXCL8 production by keratinocytes through NF-κB activation.

Anaplastic large-cell lymphomas (ALCLs) bearing the t(2;5) translocation (ALK(+)ALCLs) are frequently characterized by skin colonization and associated with a poor prognosis. Using conditional transgenic models of anaplastic lymphoma kinase-positive (ALK(+)) lymphomas and human ALK(+)ALCL cell lines, in the present study, we show that high-mobility-group box-1 (HMGB-1), a proinflammatory cytokine, is released by ALK(+) cells, and demonstrate extracellular HMGB-1-stimulated secretion of the IL-8 chemokine by HaCaT keratinocytes through the involvement of MMP-9, PAR-2, and the NF-κB pathway. Furthermore, we demonstrate that, in vitro, IL-8 is able to induce the invasiveness of ALK(+) cells, which express the IL-8 receptors CXCR1 and CXCR2. In vitro and in vivo, HMGB-1 inhibition achieved by glycyrrhizin treatment led to a drastic reduction in ALK(+) cell invasiveness. The pathophysiological relevance of our observations was confirmed by demonstrating that the HMGB-1 and IL-8 receptors are expressed in ALK(+)ALCL biopsies. We have also shown that IL-8 secretion is correlated with leukemic dissemination of ALK(+) cells in a significant number of patients. The results of the present study demonstrate for the first time a relationship among the pro-inflammatory mediators HMGB-1, MMP-9, PAR-2, and IL-8. We propose that these mediators create a premetastatic niche within the skin, thereby participating in ALK(+) lymphoma epidermotropism.

Therapy-related acute leukemia with mixed phenotype and t(9;22)(q32;q11.2): a case report and review of the literature.

Therapy-related acute leukemia showing mixed phenotype is extremely rare. We report a 49-year-old woman who presented with palpable masses in her neck and back. She had received systemic chemotherapy (adriamycin and cisplatin) and radiotherapy for endometrial adenocarcinoma 7 years before. Her peripheral blood and bone marrow showed increased blasts, which coexpressed myeloid (CD13, CD33, and myeloperoxidase) and B-lymphoid antigens (CD19 and CD79a). Cytogenetic analysis showed a karyotype of 46,XX,dup(1)(q21q32),add(5)(q33),t(9;22)(q34;q11.2)[12]/47,idem,+der(22)t(9;22)[8], and BCR/ABL1 rearrangement was detected. Leukemic infiltration was also confirmed in her back mass. After induction chemotherapy with idarubicin, cytarabine, and imatinib, she achieved complete remission. Only 2 cases of therapy-related acute leukemia with mixed phenotype have been reported so far: one with hyperploidy and the other with t(1;21)(p36;q22). To the best of our knowledge, this is the first case of therapy-related acute leukemia with mixed phenotype and t(9;22) as well as extramedullary leukemic infiltrations.

Expression levels of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and focal adhesion kinase in patients with multiple myeloma and their relationship to clinical stage and extramedullary infiltration.

We explored the expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and focal adhesion kinase (FAK) mRNA and protein, and analyzed the relationship between expression levels and clinical staging and extramedullary infiltration in patients with multiple myeloma (MM). The expression levels of mRNA and protein were measured by fluorescence quantitative polymerase chain reaction (FQ-PCR) and Western blotting. Expressions of PTEN and FAK mRNA were significantly different between patients with MM and controls. Spearman bivariate correlation analysis showed that PTEN mRNA was significantly negatively correlated with FAK mRNA. PTEN and FAK mRNA expressions were significantly different between patients with stage I + II MM and stage III MM. No difference was found in PTEN mRNA expression, whereas FAK mRNA expression was significantly different between patients with MM with and without extramedullary infiltration. PTEN protein was higher and total FAK (T-FAK) protein was significantly lower in six controls than in 12 patients with stage III MM. Phosphorylated FAK (p-FAK) protein was measured as 0.082 ± 0.040 in 11 patients with MM, but not detected in six controls. No significant difference of PTEN and T-FAK protein was found, while p-FAK protein was significantly different between patients with MM with and without extramedullary infiltration. These results indicate that abnormal expression of PTEN and FAK in patients with MM may be associated with disease progression and extramedullary infiltration.

[Spontaneous remission of congenital leukemia cutis]. / Lésions cutanées à type de leucémie congénitale "aleucémique" de rémission spontanée.

BACKGROUND: Aleukaemic leukaemia--without blasts in the blood or the bone marrow--with isolated cutaneous manifestations has been very rarely reported since only seven patients have been described to date. The prognosis is variable, and the indications for an aggressive treatment such as polychemotherapy are currently unclear. We report a case of spontaneously remitting aleukaemic leukaemia in a newborn child and compare it with other cases in the literature. CASE REPORT: A male newborn presented diffuse, violaceous skin nodules reminiscent of the so-called "blueberry muffin syndrome" present since birth. Blood and marrow examinations did not show any blasts and karyotype was normal. Biopsy of a nodule established the diagnosis of acute myeloid leukaemia type 5. The course was spontaneously favourable despite the absence of specific therapy and the boy was asymptomatic after one year of follow-up. DISCUSSION: Of the eight reported infants (including ours), three died, including two through acute transformation of the leukaemia. The prognosis seems to be highly dependent on cytogenetic features with the 11q23 rearrangement being at higher risk of acute transformation, prompting recourse to aggressive chemotherapy. Our case further illustrates the favourable prognostic value of a normal karyotype, a situation in which therapeutic abstention seems possible, and is even recommended.

Bcl-2 inhibits the innate immune response during early pathogenesis of murine congenital muscular dystrophy.

Laminin α2 (LAMA2)-deficient congenital muscular dystrophy is a severe, early-onset disease caused by abnormal levels of laminin 211 in the basal lamina leading to muscle weakness, transient inflammation, muscle degeneration and impaired mobility. In a Lama2-deficient mouse model for this disease, animal survival is improved by muscle-specific expression of the apoptosis inhibitor Bcl-2, conferred by a MyoD-hBcl-2 transgene. Here we investigated early disease stages in this model to determine initial pathological events and effects of Bcl-2 on their progression. Using quantitative immunohistological and mRNA analyses we show that inflammation occurs very early in Lama2-deficient muscle, some aspects of which are reduced or delayed by the MyoD-hBcl-2 transgene. mRNAs for innate immune response regulators, including multiple Toll-like receptors (TLRs) and the inflammasome component NLRP3, are elevated in diseased muscle compared with age-matched controls expressing Lama2. MyoD-hBcl-2 inhibits induction of TLR4, TLR6, TLR7, TLR8 and TLR9 in Lama2-deficient muscle compared with non-transgenic controls, and leads to reduced infiltration of eosinophils, which are key death effector cells. This congenital disease model provides a new paradigm for investigating cell death mechanisms during early stages of pathogenesis, demonstrating that interactions exist between Bcl-2, a multifunctional regulator of cell survival, and the innate immune response.

How I treat extramedullary acute myeloid leukemia.

Extramedullary (EM) manifestations of acute leukemia include a wide variety of clinically significant phenomena that often pose therapeutic dilemmas. Myeloid sarcoma (MS) and leukemia cutis (LC) represent 2 well-known EM manifestations with a range of clinical presentations. MS (also known as granulocytic sarcoma or chloroma) is a rare EM tumor of immature myeloid cells. LC specifically refers to the infiltration of the epidermis, dermis, or subcutis by neoplastic leukocytes (leukemia cells), resulting in clinically identifiable cutaneous lesions. The molecular mechanisms underlying EM involvement are not well defined, but recent immunophenotyping, cytogenetic, and molecular analysis are beginning to provide some understanding. Certain cytogenetic abnormalities are associated with increased risk of EM involvement, potentially through altering tissue-homing pathways. The prognostic significance of EM involvement is not fully understood. Therefore, it has been difficult to define the optimal treatment of patients with MS or LC. The timing of EM development at presentation versus relapse, involvement of the marrow, and AML risk classification help to determine our approach to treatment of EM disease.

Relapsed hepatosplenic T-cell lymphoma heralded by a solitary skin nodule.

Hepatosplenic T-cell lymphoma (HSTL) represents a rare form of peripheral T-cell lymphoma composed of lymphocytes that typically express the γδ T-cell receptor. This form of lymphoma rarely involves the skin. We report the case of a 23-year-old man with a history of HSTL that was presumed to be in remission who presented with a solitary cutaneous nodule. Skin biopsy showed an atypical lymphocytic infiltrate arranged in a perivascular and periappendageal pattern with associated vacuolar epidermal interface change. The constituent T cells expressed CD2, CD3, CD7, CD8, ß-F1, γδ T-cell receptor, Tia-1 and granzyme B. The cells lacked the expression of CD4, CD5 and CD56. Fluorescence in situ hybridization (FISH) showed a characteristic chromosomal abnormality, namely isochromosome 7q, which confirmed the diagnosis of cutaneous HSTL. On restaging his disease, widespread progression was noted. To our knowledge, this report provides the first detailed account of cutaneous involvement by HSTL. We show the novel utility of FISH to identify isochromosome 7q in the lesional skin of HSTL patients.

[Role of WAVE1 in K562 leukemia cells invasion and its mechanism].

OBJECTIVE: To investigate role of WASP family verprolin homologous protein 1 (WAVE1) in K562 leukemia cell invasion and its mechanism. METHODS: Immunofluorescence method was used to detect the distribution of WAVE1 and MMP-2 in the cells. K562 cells were transfected with pcDNA3. 1-WAVE1 reconstructed plasmid or with specific siRNA to WAVE1 gene. The invasion ability of K562 cells was examined by Transwell assay. The expression level of WAVE1 and MMP-2 in K562 cells was assayed by real-time PCR and Western blot. RESULTS: (1) WAVE1 and MMP-2 mainly expressed and co-localized in the cell membrane; (2) 24 h and 48 h after transfected with pcDNA3. 1-WAVE1, the MMP-2 mRNA level in K562 cells increased by 295% and 198% while its protein increased by 80% and 23% respectively as compared with control K562 cells. At the same time point after transfected with specific siRNA, the MMP-2 mRNA level decreased by 81% and 28%, and its protein decreased by 36% and 53% respectively as compared with control. (3) The invasion ability of K562 cells was enhanced after transfected with pcDNA3. 1-WAVE1 and depressed after transfected with the specific siRNA. CONCLUSION: The co-localization of WAVE1 and MMP-2 in K562 cells suggests they coordinate in functions; WAVE1 may involve in the migration and invasion of K562 cells through regulating the expression level of MMP-2.