Fahri Sahin

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.

The roles of bioactive sphingolipids in resveratrol-induced apoptosis in HL60 acute myeloid leukemia cells

PurposeAcute promyelocytic leukemia results from a translocation between 15 and 17 chromosomes that produce PML/RARα fusion protein. PML/RARα inhibits differentiation of myeloid precursor cells at stem cell level. Resveratrol is a phytoalexin that exerts cytotoxic effects on cancer cells. Ceramides have crucial roles in cell growth, proliferation, differentiation, drug resistance, and apoptosis. In this study, we examined the possible cytotoxic effects of resveratrol on acute myeloid leukemia cells and determined the roles of ceramide-metabolizing genes in resveratrol-induced apoptosis, in addition to investigating the possibility of increasing the sensitivity of HL60 cells to resveratrol by manipulating sphingolipids.MethodsCytotoxic effects of resveratrol, C8:ceramide, PDMP, and SK-1 inhibitor were determined by XTT cell proliferation assay. Changes in caspase-3 enzyme activity and mitochondrial membrane potential (MMP) were measured using caspase-3 colorimetric assay and JC-1 MMP detection kit. Expression levels of ceramide-metabolizing genes were examined by RT-PCR.ResultsThe results revealed that manipulations of ceramide metabolism toward generation or accumulation of apoptotic ceramides increased apoptotic effects of resveratrol in HL60 cells, synergistically. More importantly, gene expression analyses revealed that resveratrol-induced apoptosis via increasing expression levels of ceramide-generating genes and decreasing expression levels of antiapoptotic sphingosine kinase-1 and glucosylceramide synthase genes.ConclusionThese results showed for the first time that increasing intracellular levels of ceramides by biochemical approaches has also increased sensitivity of HL60 cells to resveratrol. We also showed that resveratrol induces apoptosis through manipulating ceramide-metabolizing genes that resulted in the accumulation of ceramides in HL60 cells.

Resveratrol Triggers Apoptosis Through Regulating Ceramide Metabolizing Genes in Human K562 Chronic Myeloid Leukemia Cells

Resveratrol, an important phytoalexin in many plants, has been reported to have cytotoxic effects on various types of cancer. Ceramide is a bioactive sphingolipid that regulates many signaling pathways, including cell growth and proliferation, senescence and quiescence, apoptosis, and cell cycle. Ceramides are generated by longevity assurance genes (LASS). Glucosylceramide synthase (GCS) and sphingosine kinase-1 (SK-1) enzymes can convert ceramides to antiapoptotic molecules, glucosylceramide, and sphingosine-1-phosphate, respectively. C8:ceramide, an important cell-permeable analogue of natural ceramides, increases intracellular ceramide levels significantly, while 1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP) and SK-1 inhibitor increase accumulation of ceramides by inhibiting GCS and SK-1, respectively. Chronic myelogenous leukemia (CML) is a hematological disorder resulting from generation of BCR/ABL oncogene. In this study, we examined the roles of ceramide metabolizing genes in resveratrol-induced apoptosis in K562 CML cells. There were synergistic cytotoxic and apoptotic effects of resveratrol with coadministration of C8:ceramide, PDMP, and SK-1 inhibitor. Interestingly, there were also significant increases in expression levels of LASS genes and decreases in expression levels of GCS and SK-1 in K562 cells in response to resveratrol. Our data, in total, showed for the first time that resveratrol might kill CML cells through increasing intracellular generation and accumulation of apoptotic ceramides.

Hodgkin’s lymphoma following treatment with etanercept in ankylosing spondylitis

It has been well known that anti-TNF drugs might increase lymphoma risk in rheumatoid arthritis (RA), where the rate of lymphoma has already been increased. However, unlike RA, an increased rate of lymphoma has not been reported in ankylosing spondylitis (AS). Hereby, we present a case with AS developing Hodgkin’s lymphoma (HL) following 6 months of etanercept treatment. Pathological analysis revealed mixed cellular type of HL. Although we report a single case, it should be kept in mind that anti-TNF drugs might cause lymphoma development not only in RA, but also in AS.

Dural plasmacytoma mimicking meningioma in a patient with multiple myeloma

Apart from calvarial infiltration, intracranial involvement in multiple myeloma is uncommon. Diffuse leptomeningeal invasion with or without parenchymal involvement is most common. Dural infiltration without involvement of the parenchyma, leptomeninges or skull is rare. The differential diagnosis of a dural plasmacytoma includes meningioma, which has a similar MRI appearance, metastasis, lymphoma and sarcoma of the dura mater. We present a patient with multiple myeloma presenting with an intracerebral mass mimicking a meningioma on MRI. Multiple myeloma had been diagnosed seven years previously. The patient presented with headache and speech disturbance 12 months after autologous peripheral stem cell transplantation for recurrence of multiple myeloma. MRI revealed a left temporal extra-axial mass with a dural tail mimicking meningioma. Histopathological examination of the mass after excision showed multiple myeloma immunopositive for IgG, kappa light chain and CD38. There was no recurrence after postoperative radiotherapy. Plasmacytoma should be considered in the differential diagnosis of a solitary dural mass, particularly in a patient with multiple myeloma.

Quercetin-induced apoptosis involves increased hTERT enzyme activity of leukemic cells

Abstract We aimed to examine the growth suppressive effects of quercetin on acute promyelocytic and lymphoblastic leukemia and chronic myeloid leukemia, and to find out whether the growth suppression is related to the blocking of telomerase enzyme activity. Cytotoxic effects of quercetin were shown by trypan blue analyses. Apoptotic effects of quercetin were examined by acridine orange and ethidium bromide staining by fluorescence microscopy. The effects of quercetin on telomerase enzyme activity were shown by hTERT Quantification Kit. Our results demonstrated that quercetin has antiproliferative and apoptotic effects on T-cell acute lymphoblastic leukemia (ALL), acute promyelocytic leukemia, and chronic myeloid leukemia (CML) cells. We also showed for the first time by this study that quercetin suppresses the activity of telomerase in ALL and CML cells. The results of this study show the importance of quercetin for its therapeutic potential in treatment of leukemias.

Cardiac thrombi in a patient with protein-C and S deficiencies: a case report

We report a case of multiple mobile intra-cardiac thrombi accompanying recurrent pulmonary embolism that has been successfully treated by fibrinolytic therapy. Control transesophageal echocardiographic examination showed that prolonged thrombolytic treatment completely removed the thrombi. Surgical removal of emboli has been validated but cannot be proposed to all patients since it is a high-risk intervention. Fibrinolysis is generally efficient but exposes the patient to risk of migration of the intra-cavity thrombus, with occasionally deleterious evolution. Systemic thrombolytic therapy is usually recommended if (a) it is not contraindicated and (b) the thrombi are demonstrated in more than one cardiac chamber, entailing a higher risk of surgical intervention. However, the infusion rate and duration of thrombolytic therapy are important determinants of successful and uncomplicated lysis. Low dose and long infusion time should be chosen to avoid fragmentation of the thrombus and related complications.

Peripheral blood stem cell mobilization from healthy donors

Most frequently used graft of hematopoietic stem cells (HSCs) for allogeneic transplantation is peripheral blood stem cells (PBSCs) that are collected after mobilization with frequently granulocyte colony-stimulating factor (G-CSF). Administration of the optimal dose of G-CSF while preserving the donor health is one of the most important points for sufficient PBSC mobilization and harvest. We hereby tried to summarize characteristic features, potential side effects and main topics in peripheral blood stem cell mobilization from healthy donors.

Primary diffuse large B-cell lymphoma of the lacrimal sac simulating chronic dacryocystitis ☆

Primary diffuse large B-cell lymphoma of the lacrimal sac is rare. Herein we report a 55-year-old female presented with epiphora in the right eye. Distention of the lacrimal sac secondary to nasolacrimal duct obstruction was observed. She was scheduled for external dacryocystorinostomy for the next month. When she came for surgery, a growing mass was recognised over the lacrimal sac region. On computer tomography scan, a subdermal mass causing nasal bone destruction was detected. Excisional biopsy of the mass was performed. Histopathologic and immunohistochemical evaluations revealed primary diffuse large B-cell non-Hodgkin lymphoma of the lacrimal sac. She was treated with cyclophospamide, vincristine, adriablastine and prednisone for eight courses combined with rituximab for 6 months. During a follow-up period of 25 months, patient is stable with no systemic disease. Although rare, lacrimal sac tumors can mimic dacryocystitis and must be considered in differential diagnosis. In suspicious cases incisional biopsy is recommended.

Effects of Hormone Replacement Therapy on Insulin Resistance and Platelet Function Tests

Objectives: The aim of this study was to evaluate measures of insulin resistance and platelet function in postmenopausal women with oral or transdermal hormone replacement therapy (HRT). Subjects and Methods: Eighty women divided into four groups of 20 each were enrolled in the study. Group 1: postmenopausal hysterectomized women who received only transdermal estradiol (13.9 mg/12.5 cm2); group 2: women with intact uterus who were treated with estrogen-progestin combination (HRT); group 3: postmenopausal women who were treated with the selective estrogen receptor modulator tibolone, and group 4: women who were not taking any drugs for HRT were chosen as a control group (group 4). Results: In group 2, homeostasis model assessment of insulin resistance and fasting insulin levels were 2.90 ± 0.37 and 9.3 ± 3.0 µU/ml, respectively, prior to administration of HRT. These levels were reduced to 1.91 ± 0.41 (p = 0.001) and 7.1 ± 2.7 µU/ml (p = 0.002), respectively, after drug therapy. Mean levels of high-sensitivity C-reactive protein (hsCRP) were decreased with HRT only in group 2 (p = 0.002). No changes for biochemical and hematological parameters were observed in the other groups. Platelet function tests showed no differences after HRT in any group. Conclusions: Estrogen-progestin combination HRT decreased measures of insulin resistance and hsCRP levels, but had no effect on platelet function tests in postmenopausal women.