Effects of fludarabine and gemcitabine on human acute myeloid leukemia cell line HL 60: direct comparison of cytotoxicity and cellular Ara-C uptake enhancement.

This study was designed to compare the effects of fludarabine and gemcitabine on cytosine arabinoside (Ara-C) uptake and retention, and their specific cytotoxicity on HL 60 human acute myeloid leukemia cells. The leukemic blasts were exposed to either drug at equimolar concentrations (10 microM) for 3 h and further incubated with Ara-C (5 microM), added immediately (day 0) or after an interval of 24 h in cells were kept in a drug free medium (day 1). On day 0, leukemic cells exposed to fludarabine 10 microM had a significant (P<0.01) increase in Ara-C uptake (297 +/- 11 pmol/10(7) cells) with respect to control cells (not pre-treated: 195 +/- 10 pmol/10 (7) cells). After treatment of leukemic cells with fludarabine, cytoplasmic Ara-C peaked after 180 min of exposure, as well as nuclear bound Ara-C. At the same time, a significant decrease in the number of S-phase leukemic cells, consistent with depressed [3 H]TdR uptake was observed. Although on day 0 gemcitabine 10 microM did not have potentiating effects on Ara-C uptake, it showed a high degree of intrinsic cytotoxicity as a single agent(clear from cell cycle distribution, [3H]TdR uptake, plating efficiency (PE) data and percentage of apoptotic cells). Cells exposed to gemcitabine, on the other hand, showed on day 1 a significant increase in Ara-C uptake (2.4 x control values in the cytoplasmic and 3x in the nuclear fractions) and a reduced number of S-phase blasts, [3H]TdR uptake and PEs, as well as an increased apoptotic cell death. Evidently, it is possible to modulate Ara-C uptake by leukemic cells with gemcitabine. Although this effect is similar to that demonstrated with fludarabine, its kinetics and time of efficacy are different and also, because of its intrinsic higher cytoxicity and lack of important side effects, gemcitabine could be considered a suitable candidate for Ara-C association therapy in acute leukemia.

Serum melatonin in multiple myeloma: natural brake or epiphenomenon?

Melatonin (MEL), the main hormone produced by the pineal gland, seems to exert antineoplastic activity both in vitro and in vivo. Moreover, several studies reported increased melatonin blood levels in cancer patients. Plasma melatonin concentrations were determined in 46 patients with multiple myeloma and in 31 age matched healthy subjects (57.8 +/- 6.9 versus 55.2 +/- 8.9 years). Venous blood was drawn between 7.30 and 9.30 a.m. and melatonin was assayed using a commercially available radioimmunoassay. The data were analysed by Student's t test and results reported as mean values +/- standard deviation. The patients with multiple myeloma showed significantly higher mean melatonin serum levels than healthy subjects (21.6 +/- 13.5 versus 12.1 +/- 4.8 pg/ml; p < 0.001). This behaviour could actually represent a phenomenon secondary to an altered endocrine-metabolic balance caused by an increased demand of the developing tumor. On the other hand, the increased melatonin secretion might be considered as a compensatory mechanism due to its antimitotic action and therefore as an effort to secrete substances capable of regulating neoplastic growth.

Apoptotic and antiproliferative effects of gemcitabine and gemcitabine plus Ara-C on blast cells from patients with blast crisis chronic myeloproliferative disorders.

BACKGROUND: Blast phase of chronic myeloid leukemia (CML) as well as the rare acute transformation of other chronic myeloproliferative disorders constitute forms of leukemia that are particularly refractory, even to aggressive chemotherapy. Many attempts have thus been made to identify new drugs that could be active in these diseases. We wanted to evaluate whether gemcitabine (dFdC), a pyrimidine analogue widely employed in lung cancer chemotherapy, was able to block in vitro proliferation of bcr/abl-positive and bcr/abl-negative blast cells in primary culture. We already showed that gemcitabine is active in inhibiting proliferation and inducing apoptosis of HL60 cells. METHODS: We studied the influence of dFdC on the proliferative potential of blasts by means of tritiated thymidine uptake, colony formation in semisolid medium and cell cycle parameters at flow cytometry. The efficacy of dFdC in inducing apoptosis was evaluated by flow cytometry (A0 peak) and by DNA agarose gel electrophoresis. RESULTS: We demonstrated that dFdC already inhibits tritiated thymidine uptake at doses of 10 microM after 72 hours of culture, and that this effect is dose dependent. The addition of Ara-C 5 microM in the culture medium of dFdC provoked a synergistic inhibitory effect. Consistent results were obtained when cell cycle distribution was studied. In fact, cell incubation in the presence of dFdC resulted in a significant decrease of cells in S phase, although with a certain heterogeneity among cases. The antileukemic activity of dFdC appeared to be specific since it was mediated through apoptosis. We could demonstrate the appearance of the pre-G1 apoptotic peak at cytofluorimetric analysis, and the characteristic DNA fragmentation pattern at agarose electrophoresis in all 10 cases after treatment with different doses of dFdC. Induction of apoptosis was maximal for the highest doses of dFdC (100 mM) and for the combination of dFdC and Ara-C. INTERPRETATION AND CONCLUSIONS: Following incubation with Gemcitabine leukemic blasts from chronic myeloproliferative disorders are induced to accumulate intracytoplasmatic and nuclear Ara-C and undergo apoptosis. These observations suggest that gemcitabine could be considered a candidate drug, capable of being used in polychemotherapy of refractory acute phase chronic myeloproliferative disorders.

Pure red cell aplasia in autoimmune polyglandular syndrome with T lymphocytosis.

We report the onset of pure red cell aplasia (PRCA) in a patient with a history of polyglandular syndrome including Addison's disease, malabsorption syndrome, diabetes type I and gastric hyperplastic polyposis. An autoimmune origin for this complex disorder was not supported by the presence of organ specific antibodies, but T cells were found to be of polyclonal origin, as demonstrated by molecular analysis of T cell receptor (TCR) gene rearrangement. The pathophysiology of this case, based on laboratory findings and response to therapy, is discussed.

Detection of bcr/abl transcripts by RT-PCR and their colorimetric evaluation in chronic myeloid leukemia patients receiving allogeneic bone marrow transplantation.

BACKGROUND: Chronic myeloid leukemia (CML) is a disease characterized by the presence of a unique molecular marker, i.e. the fusion gene bcr-abl and its mRNA and protein products. This marker permits minimal residual disease follow-up after bone marrow transplantation (BMT) through cytogenetic or molecular analysis. Although the reverse transcriptase polymerase chain reaction (RT-PCR) method is largely employed, the clinical value and impact of a positive RT-PCR as a herald of hematological relapse has not yet been definitively ascertained. METHODS: In order to verify the frequency of bcr-abl positivity in CML patients who underwent alloBMT, we performed serial two-step RT-PCR on 63 peripheral blood and bone marrow specimens obtained at different times after non T-cell-depleted BMT from 16 CML patients treated in our Institution. After amplification, RT-PCR products were always checked by liquid hybridization with a specific probe. Median molecular follow-up after BMT was 38 months (range 2-144 months). RESULTS: None of the patients studied presented clinical hematological relapse after BMT. Six out of sixteen patients were found to be positive for bcr-abl. PCR positivity appeared in 4/6 patients more than one year post-BMT and in 2/6 patients within one year post BMT. In both instances PCR was an isolated finding in 5/6 patients and reverted to negativity in subsequent analysis; only one case was PCR-positive twice. It is noteworthy that RT-PCR positivity appeared in five patients presenting acute or chronic graft versus host disease (GVHD) and in one patient who had received MUD-BMT. CONCLUSIONS: In our cohort of patients, transient bcr-abl positivity had no clinical relevance and was also found in MUD-BMT without heralding hematological relapse. Our observations further stress the importance of applying only quantitative PCR methods during the post BMT follow-up of CML patients.

Induction of apoptosis by monosaccharide butyrate stable derivatives in chronic lymphocytic leukemia cells.

BACKGROUND AND OBJECTIVE: Different therapeutic approaches are needed to restore apoptotic mechanisms in CLL cells, as present ones are not successful. We assessed the apoptotic effects of stable butyrate derivatives on CLL lymphocytes: in these molecules a mannose molecule is bound as ester to one-five butyrate moieties, conferring pharmacological stability to the pro-drugs which are able to induce apoptosis in primary AML blasts. DESIGN AND METHODS: Peripheral blood samples obtained from 17 patients with typical B-CLL were cultured in the presence of 0.5-1mM D1 (O-n-butanoyl-2, 3-O-isopropylidene-a-D-mannofuranoside), F1 (1-O-n-butanoyl-2, 3-O-isopropylidene-D,L-xylitol) and G1 (1-O-n-butanoyl-D,L-xylitol) derivatives for 4 days and equimolar sodium butyrate as comparison. After culture, apoptosis was evaluated by cell morphology, cellular DNA content, pattern of DNA fragmentation, annexin V exposure on cell membrane, and cell cycle parameters. Bcl2, bax, and fas oncogene expression were also evaluated by the APAAP method. RESULTS: The addition to cell cultures of D1 or F1 or G1 butyrate monosaccharides as well as sodium butyrate 0.5 and 1 mM determined to different extents an increase in the percentage of apoptotic cells in all CLL samples, relatively to the method and butyrate molecule added in culture. Heterogeneity in CLL cell sensitivity to the three butyrates was observed. Up to 60-68% apoptotic bodies were present in treated cultures after exposure to D1 0.5-1 mM, 60-72% after F1 0.5-1 mM and 48-60% after G1 0.5-1 mM. Comparison of untreated versus treated cultures yielded important significance (p< 0.001). At DNA content analysis, analyzed by flow cytometry, apoptotic events were accounting for up to 70-77% of D1-treated and 68-74% of F1-treated CLL cells at 0.5 and 1 mM concentrations (p= 0. 0001, vs controls 0-39%), and for 72-81% of G1 (0.5-1 mM) treated cells (overall, p=0.005). Cell cycle parameters were not altered by addition of butyrates, but expression of Annexin V was greatly enhanced. In a limited number of CLL cases fas, bcl2/bax ratio was analyzed and found unmodified. INTERPRETATION AND CONCLUSIONS: Monosaccharide butyrate stable derivatives are potent inducers of primary CLL cell apoptosis, both in untreated and alkylating agent pre-treated cases. Our results suggest that the apoptotic pathways elicited by butyrate in CLL lymphocytes are direct, specific and most probably do not involve bcl2/bax. Pro-apoptotic agents like the stable monosaccharide butyrate derivatives here studied could bring more insights into CLL biology and resistance to apoptosis, and possibly originate alternative treatments for CLL.