Filiz Büyükkeçeci

Involvement of protein phosphatase 2A in interferon-α-2b-induced apoptosis in K562 human chronic myelogenous leukaemia cells

Interferon-alpha (IFN-alpha)-2b is known to have antiproliferative effects on hematological malignant cells, especially chronic myelogenous leukaemia (CML). However, it can induce cytogenetical remissions in a very small percentage of the patients. Also during interferon therapy, resistance can emerge in the CML clones. K562 is an in vitro model cell line transformed from a Ph positive CML patient. It can be induced to differentiate to granulocytic and/or monocytic lineages with certain molecules. IFN-alpha-2b generally exerts its effects on CML cells by Janus family kinases (Jak/Stat) pathway, mostly through tyrosine kinase system. However, there is almost no data on the relevance of serine/threonine (Ser/Thr) protein phosphatase (PP) system in the interferon induced signal transduction pathways. In this study, we investigated serine/threonine protein phosphatases in the IFN-alpha-2b induced K562 cytotoxicity. Trypan blue dye exclusion test and MTT assay were utilised for determining cytotoxicity. IC(50) of IFN-alpha-2b on K562 cells was found to be 600IU/ml. However, no differentiation was determined by analysis of cell surface antigen expressions. Serine/threonine protein phosphatase inhibitors calyculin A (Cal A) and okadaic acid (OKA) augmented the IFN-alpha-2b induced cytotoxicity. Apoptosis assay by the mono-oligonucleosome detection and acridine orange/propidium iodide dye revealed marked apoptosis underlying cytotoxicity. Phosphatase enzyme assay revealed a gradual increase in protein phosphatase 2A (PP2A) activity during interferon induced cytotoxicity. Conversely, immunoblots showed no change in the expression of PP2A catalytic and regulatory subunits. In conclusion, PP2A plays a role in IFN-alpha-2b induced apoptosis of K562 cells and should be investigated as a new window furthermore.

Augmentation of methylprednisolone-induced differentiation of myeloid leukemia cells by serine/threonine protein phosphatase inhibitors

To elucidate the roles of serine/threonine protein phosphatases type 1 (PP1) and type 2A (PP2A) in methylprednisolone-induced differentiation of HL60 cells into granulocytes and K562 cells into monocytes, we examined the effect of serine/threonine protein phosphatase inhibitors, okadaic acid and Cal-A on the proliferation/differentiation of HL60 and K562 cells. Okadaic acid and Cal-A augmented methylprednisolone induced granulocytic differentiation and cell death of HL60 cells and monocytic differentiation and cell death of K562 cells in different dose ranges, respectively. These data suggest an important role of PP1 and PP2A in the mechanism leading to differentiation of leukemic cells.

Mitoxantrone and standard dose cytosine arabinoside therapy in refractory or relapsed acute leukemia.

Thirty adult patients with relapsing or refractory acute leukemia were treated with mitoxantrone 10 mg/m2 daily by 20-min intravenous infusion for 5 days and cytosine arabinoside (Ara-C) 200 mg/m2 daily by continuous infusion for 5 days. Complete remission was obtained in 9 of 15 patients (60%) with acute myeloblastic leukemia (AML), with a mean duration of 6 months (range 2-12 months). Among 15 patients with acute lymphoblastic leukemia (ALL), complete remission was obtained in 5 patients (33.3%), with a mean duration of 2 months. Partial remission was achieved in 2 patients with AML and 1 patient with ALL. Myelosuppression developed in all patients following chemotherapy. Nonhematologic side effects consisted of nausea, vomiting, mild alopecia, stomatitis and transient hepatic dysfunction. No cardiopulmonary toxicity or neurotoxicity was observed. Our therapeutic responses are similar to those obtained with high-dose Ara-C and mitoxantrone but with less toxicity.

Incidence of aplastic anemia in Turkey: A hospital-based prospective multicentre study

The incidence of aplastic anemia among hospitalized adult patients was prospectively determined in this first study in Turkey. New cases of aplastic anemia among patients 14 years and older who were admitted to the study centers were included in a 3 year survey. Seventy-three patients fulfilled the diagnostic criteria, yielding a mean annual incidence rate of 1.14 cases in 10(3) admissions. The male-to-female ratio of the cases (1.6:1) differed from the almost equal ratio of the larger population of Turkey. The median age was 30 years and females were younger at diagnosis. The age distribution of the cases was different from that of the population; showing two incidence peaks in both sexes. The majority of the patients (89%) had severe disease.

Two Consecutive Spontaneous Regressions to Chronic Phase in a Patient with Blastic Transformation of Chronic Myelogenous Leukemia

In this report, we present a patient with chronic myeloid leukemia (CML) in blastic phase who had two consecutive episodes of spontaneous regression back to chronic phase without chemotherapy. Although, spontaneous remission (SR) is well documented in acute leukemia, SR in CML blastic phase is extremely rare and to the best of our knowledge only one case has been reported in the world literature. The factors possibly related to this phenomenon are discussed.

Eltrombopag for the Treatment of Immune Thrombocytopenia: The Aegean Region of Turkey Experience.

Objective: Immune thrombocytopenia (ITP) is an immune-mediated disease characterized by transient or persistent decrease of the platelet count to less than 100x109/L. Although it is included in a benign disease group, bleeding complications may be mortal. With a better understanding of the pathophysiology of the disease, thrombopoietin receptor agonists, which came into use in recent years, seem to be an effective option in the treatment of resistant cases. This study aimed to retrospectively assess the efficacy, long-term safety, and tolerability of eltrombopag in Turkish patients with chronic ITP in the Aegean region of Turkey. Materials and Methods: Retrospective data of 40 patients with refractory ITP who were treated with eltrombopag in the Aegean region were examined and evaluated. Results: The total rate of response was 87%, and the median duration of response defined as the number of the platelets being over 50x109/L was 19.5 (interquartile range: 5-60) days. In one patient, venous sinus thrombosis was observed with no other additional risk factors due to or related to thrombosis. Another patient with complete response and irregular follow-up for 12 months was lost due to sudden death as the result of probable acute myocardial infarction. Conclusion: Although the responses to eltrombopag were satisfactory, patients need to be monitored closely for overshooting platelet counts as well as thromboembolic events.

Sclerosing Extramedullary Hematopoietic Tumor Mimicking Intra-abdominal Sarcoma

Sclerosing extramedullary hematopoietic tumor (SEMHT) is a rare tumor that occurs in patients with chronic myeloproliferative disorders (CMPDs). The tumor is classified in the chronic idiopathic myelofibrosis (MF) subgroup, and cases have been reported at various localizations since 1980 [1-4]. Such tumors are usually seen in the abdominal organs, retroperitoneum, and mesenteric region [3]. The clinical, radiological, and morphological features may complicate differentiation from sarcoma, carcinoma, and lymphoma. It is sometimes also difficult to differentiate between a SEMHT and extramedullary hematopoiesis (EMH). These two lesions have similar clinical features, but EMH is morphologically more cellular. To aid in the differentiation, SEMHT has a more solid mass appearance with dense fibrosis and atypical megakaryocytes [3]. EMH is the presence of hematopoietic tissue in locations other than the bone marrow. The basic mechanism is bone marrow dysfunction and decreased production of hematopoietic cells, followed by production of bone marrow cells in other organs and tissues. EMH is seen in many disorders such as sickle cell anemia, hemoglobinopathies, thalassemia, hereditary spherocytosis, and MF [5]. EMH is most commonly observed in the liver and spleen and is rarely found in the peritoneum, lymph nodes, kidneys, thymus, central nervous system, retroperitoneum, myocardium, uterus, pleura, paraspinal region, or intestines [6-9].

Molecular Evaluation of t(14;18)(bcl-2/IgH) Translocation in Follicular Lymphoma at Diagnosis Using Paraffin-Embedded Tissue Sections.

Objective: Follicular lymphoma (FL) is one of the most common lymphomas, and is characterized by t(14;18)(q32;q21) in more than 80% of patients. The aim of this study was to determine the rate of t(14;18) positivity based onthe detection of mbr or mcr in paraffin-embedded tissue samples. Material and Methods: The study included 32 paraffin-embedded tissue samples collected from 32 consecutive FL patients that were diagnosed and followed-up at our hospital between 1999 and 2006. The MBR breakpoint wasidentified based on real-time PCR using a LightCycler v.2.0 t(14;18) Quantification Kit (MBR), multiplex PCR, and seminestedPCR. To identify the mcr breakpoint, real-time PCR was performed using specific primers and the FastStart DNAMaster SYBR Green I Kit. To detect t(14;18) via fluorescence in situ hybridization (FISH) nuclei from paraffin-embeddedtissue sections were extracted and used together with LSI IgH (immunoglobulin heavy chain) (spectrum green)/bcl-2(B-cell leukemia-lymphoma 2) (spectrum orange) probes. Results: The DNA and nuclei isolation success rate for B5 formalin-fixed, paraffin-embedded tissue sections (n = 12)was 42% and 33%, respectively, versus 95% and 60%, respectively, for 20 tissue sections fixed in formalin only. In all,24 paraffin-embedded tissue sections were analyzed and mbr positivity was observed in the DNA of 82.14% via seminested PCR, in 53.57% via multiplex PCR, and in 28.57% via real-time PCR. We did not detect mcr rearrangementin any of the samples. In all, 15 of 16 patients (93.75%) whose nuclei were successfully isolated were observed to bet(14;18) positive via the FISH method. Conclusion: Semi-nested PCR and FISH facilitated the genetic characterization of FL tumors. As such, FISH and PCR complement each other and are both essential for detecting t(14;18) translocation.

İmatinib Mesilat ile Tedavi Edilen Kronik Myeloid Lösemi Vakalarında Belirlenen Trizomi 8

Kronik myeloid losemi vakalarinda t(9;22)(q34;q11) translokasyonu sonucu Philadelphia (Ph) kromozomu olusmakta ve bu translokasyon bcr-abl gen fuzyonuna yol acmaktadir. Imatinib mesilat (STI571, Glivec) bcr-abl gen fuzyonu sonucu sentezlenen bcr-abl tirozin kinaz proteininin inhibitorudur. Ileri faz kronik myeloid losemi vakalarinda en sik gozlenen sekonder karyotipik anomaliler, ikinci Ph, trizomi 8, izokromozom 17q ve trizomi 19 dur. Cok sayida vakada Ph(-) ve Ph(+) hucrelerde klonal karyotipik anomaliler gelismektedir. Bu calismada imatinib mesilat ile tedavi edilmis biri Ph(-) trizomi 8, ucu de Ph(+) trizomi 8 olmak uzere dort vaka rapor edilmektedir