Sze-Fai Yip

A novel zebrafish jak2aV581F model shared features of human JAK2V617F polycythemia vera

OBJECTIVEnThe Janus kinase 2 (JAK2) is important for embryonic primitive hematopoiesis. A gain-of-function JAK2 (JAK2(V617F)) mutation in human is pathogenetically linked to polycythemia vera (PV). In this study, we generated a zebrafish ortholog of human JAK2(V617F) (referred herewith jak2a(V581F)) by site-directed mutagenesis and examined its relevance as a model of human PV.nnnMATERIALS AND METHODSnZebrafish embryos at one-cell stage were injected with jak2a(V581F) mRNA (200pg/embryo). In some experiments, the embryos were treated with a specific JAK2 inhibitor, TG101209. The effects of jak2a stimulation on hematopoiesis, jak/stat signaling, and erythropoietin signaling were evaluated at 18-somites.nnnRESULTSnInjection with jak2a(V581F) mRNA significantly increased erythropoiesis, as enumerated by flow cytometry based on gfp(+) population in dissociated Tg(gata1:gfp) embryos. The response was reduced by stat5.1 morpholino coinjection (control: 4.37% +/- 0.08%; jak2a(V581F) injected: 5.71% +/- 0.07%, coinjecting jak2a(V581F) mRNA and stat5.1 morpholino: 4.66% +/- 0.13%; p<0.01). jak2a(V581F) mRNA also upregulated gata1 (1.83 +/- 0.08 fold; p=0.005), embryonic alpha-hemoglobin (1.61 +/- 0.12 fold; p=0.049), and beta-hemoglobin gene expression (1.65 +/- 0.13-fold; p=0.026) and increased stat5 phosphorylation. These responses were also ameliorated by stat5.1 morpholino coinjection or treatment with a specific JAK2 inhibitor, TG101209. jak2a(V581F) mRNA significantly reduced erythropoietin gene (0.24 +/- 0.03 fold; p=0.006) and protein expression (control: 0.633+/-0.11; jak2a(V581F) mRNA: 0.222+/-0.07 mIU/mL; p=0.019).nnnCONCLUSIONnThe zebrafish jak2a(V581F) model shared many features with human PV and might provide us with mechanistic insights of this disease.

Cytomegalovirus infection associated with clonal proliferation of T-cell large granular lymphocytes: causal or casual?

Clonal proliferation of T-cell large granular lymphocytes (LGL) is an indolent disorder characterized by splenomegaly, lymphocytosis and frequent manifestations of immune disturbances. The LGL are CD3(+) CD4(-) CD8(+) CD56(-). The clonality of the tumor cell population is often only demonstrable by T-cell receptor (TCR) gene rearrangement study because chromosomal abnormality is distinctly rare. We describe a case of T-cell LGL leukemia that presented initially as cytomegalovirus infection. The leukemic LGL are shown to be clonal by both TCR gene rearrangement and chromosomal studies. They persist after subsidence of the cytomegalovirus infection.

Clofarabine and high-dose cytosine arabinoside in the treatment of refractory or relapsed acute myeloid leukaemia

Clofarabine (40xa0mg/m2/dayu2009×u20095) and high-dose cytosine arabinoside (Ara-C, 1–2xa0g/m2/dayu2009×u20095) were used in 10 men and 11 women, at a median age of 45 (22–62)u2009years, with refractory (Nu2009=u20094) and relapsed (Nu2009=u200917) acute myeloid leukaemia, after a median of 3 (2–5) prior regimens. Grade 4 myelosuppression was observed in all cases, with two patients dying of bacterial sepsis. Nine patients achieved a complete remission. Disease status, number of prior therapies, and cytogenetic aberrations were not associated with the outcome. However, remission was only achieved with Ara-C at 2xa0g/m2/day and not 1xa0g/m2/day (9/15 versus 0/4, Pu2009=u20090.03).

Aberrant gene promoter methylation marking disease progression in multiple myeloma

The pathogenesis of multiple myeloma (MM), a neoplastic proliferation of monoclonal plasma cells, is a multi-step process with progressive acquisition of genetic aberrations. Disease initiation involves the activation of oncogenes such as D-type cyclins by chromosomal translocations involving the immunoglobulin (Ig) gene. Inactivation of tumor suppressor genes, however, appears to be a late event. Clinically, the disease may progress through monoclonal gammopathy of undetermined significance, smouldering myeloma, MM and plasma cell leukemia. DNA methylation involves the addition of a methyl group to the carbon 5 position of the cytosine ring. Aberrant methylation in the CpG dinucleotide regions of gene promoters results in transcription repression, and may act as an alternative mechanism of gene inactivation. In myeloma, aberrant methylation is a frequent genetic alteration that results in perturbation of signaling pathways. For instance, we had shown previously that aberrant methylation of SHP1 was associated with absent SHP1 expression, resulting in constitutive activation of the Jak/ STAT pathway. Demethylation with 5-azacytidine led to re-expression of SHP1 and downregulation of Jak/STAT signalling, thus demonstrating that aberrant methylation was biologically relevant. Several putative tumor suppressor genes such as SHP1 (targeting interleukin-6 (IL-6) signaling), DAP kinase (targeting p53-mediated apoptosis), CDKN2A (targeting the cell cycle) and E-CAD are frequently methylated in MM, and thus might be acquired during disease evolution. Here, we describe the methylation status of multiple genes in four patients with MM, where disease evolution was punctuated by progressive gene hypermethylation.

The lack of association between JAK2 V617F mutation and myelodysplastic syndrome with or without myelofibrosis.

The lack of association between JAK2 V617F mutation and myelodysplastic syndrome with or without myelofibrosis

Fatal diffuse alveolar damage complicating acute myeloid leukemia with abnormal eosinophils and trisomy X.

Abstract. We describe a case of acute myeloid leukemia (AML) with abnormal eosinophils in a 44-year-old Chinese woman that was complicated by diffuse alveolar damage (DAD) and pulmonary hemorrhage (PH) shortly after induction chemotherapy. Cytogenetic study of bone marrow cells at diagnosis showed a rare aberration of trisomy X (+X) as the sole acquired karyotypic abnormality. We speculate that tissue damage by cellular constituents of the abnormal eosinophils that were released on cell lysis after chemotherapy might be etiologically linked to the occurrence of fatal pulmonary complications.

Two balanced and novel chromosomal translocations in myeloid malignancies: characterization by multiplex fluorescence in situ hybridization

We describe two novel chromosomal translocations in two cases of leukemia in which these translocations were further characterized as the sole acquired karyotypic abnormality by mutliplex fluorescence in situ hybridization (M-FISH). They comprised a case of acute myeloid leukemia with t(6;10)(q21;p12) and a case of chronic myelomonocytic leukemia with t(5;12)(q34;q24). To the best of our knowledge, these two balanced translocations are novel and are hitherto unrecognized in hematologic malignancies. While the clinical and pathogenic significance of these translocations remains to be defined, the present report illustrates that M-FISH technology contributes to the exclusion of subtle or cryptic translocations in sole karyotypic aberrations and the confirmation of novel chromosomal arrangements in neoplastic disorders.

Long-term outcome of relapsed acute promyelocytic leukemia treated with oral arsenic trioxide-based reinduction and maintenance regimens: A 15-year prospective study: Oral As2O3 for Relapsed APL

For patients who have acute promyelocytic leukemia (APL) in second complete remission (CR2), optimal postremission strategies remain undefined.

Subarachnoid haemorrhage: more than meets the eye

A 63-year-old man with acute promyelocytic leukaemia (APL) in third complete remission (CR3) presented with persistent headache. Previous treatment had included all-trans retinoic acid (ATRA) and chemotherapy (12 years ago, CR1), arsenic trioxide (As2O3) and chemotherapy (4 years ago, CR2), and ATRA, As2O3 and chemotherapy (2 years ago, CR3). A noncontrast axial computerised tomography (CT) scan showed a diffuse increase in density within the subarachnoid space and sulci (top left), typical of subarachnoid haemorrhage (SAH). Owing to neurological deterioration, a ventriculostomy was performed. The cerebrospinal fluid (CSF) was not bloodstained or xanthochromatic, but contained hypergranular blasts (top right) showing reciprocal PML and RARA fusion (insert), confirming leukaemic relapse in the central nervous system (CNS). On the magnetic resonance imaging (MRI), the T1-weighted scans showed relatively unremarkable sulci with normal hypo-intense CSF (bottom left), excluding the presence of blood. However, Gadolinium-enhanced T1-weighted scans showed diffuse enhancement in the leptomeninges and at the superficial sulci (bottom right), consistent with leptomeningeal leukaemia. Bone marrow examination was normal. The diagnosis was therefore isolated CNS relapse of APL. Acute SAH is characterised on plain CT scan by hyperdensity in the subarachnoid space, particularly in the basal, interhemispheric and insular cisterns, and the superficial sulci. In this exceptional case, severe leptomeningeal leukaemic infiltration resulted in a diffuse enhancement of the leptomeninges on plain CT scanning, leading to confusion with the appearance of SAH. Isolated relapse of APL in the CNS has been increasingly reported after ATRA therapy. The presentation is variable, including headache, mental confusion and symptoms of a space-occupying lesion. Finally, it is important to note that the diagnosis of SAH in an APL patient, which is not uncommon, by plain CT scanning may have to be supplemented with MRI to differentiate from leukaemic infiltration.

Clinicopathologic features and prognostic indicators in Chinese patients with myelofibrosis

Objective: To define the clinicopathologic features, outcome, and prognostic indicators of myelofibrosis (MF) in Asian patients. Methods: Two hundred and seventy consecutive Chinese patients (primary MF, nu2009=u2009207; post-polycythemia vera MF, nu2009=u200927; and post-essential thrombocythemia MF, nu2009=u200936) from seven regional referral hospitals were analyzed. Results: The median overall survival (OS) for primary MF was 66 months. Multivariate analysis showed that age >65 years (Pu2009=u20090.02), platelet countu2009<100u2009×u2009109/l (Pu2009=u20090.001), and leukemic transformation (Pu2009=u20090.001) negatively impacted on OS. The median OS of 63 patients with secondary MF was 44 months. In primary MF, the 10-year cumulative risk of leukemic transformation was 28%. On multivariate analysis, unfavorable karyotypes significantly predicted inferior leukemia-free survival (LFS) (Pu2009=u20090.03). In secondary MF, the 10-year cumulative risk of leukemic transformation was 31%. Circulating blasts ≥1% significantly predicted inferior LFS (Pu2009=u20090.04). The international prognostic scoring system (IPSS) and dynamic IPSS were not significant survival predictors in our cohort. Eighteen patients underwent allogeneic hematopoietic stem cell transplantation. The median OS post-transplantation was merely 19 months. Discussion: Platelet countu2009<100u2009×u2009109/l, unfavorable karyotypes, and circulating blasts >1% were negative prognostic indicators. Conclusion: Chinese MF patients were similar to Western patients in clinicopathologic features and outcome.