Synthesis and induction of apoptosis in B cell chronic leukemia by diosgenyl 2-amino-2-deoxy-beta-D-glucopyranoside hydrochloride and its derivatives

2-Acetamido-2-deoxy-D-glucose hydrochloride (D-glucosamine hydrochloride) has been used for the preparation of 1,3,4,6-tetra-O-acetyl-2-deoxy-2-trifluoroacetamido-beta- (4) and 2-tetrachlorophthalimido-alpha,beta-D-glucopyranose (6), which have been transformed into the appropriate bromides and the chloride. Both bromo and chloro sugars were used as a glycosyl donors for the glycosylation of diosgenin [(25R)-spirost-5-en-3beta-ol]. These condensations were conducted under mild conditions, using silver triflate as a promoter, and gave diosgenyl glycosides 9 and 12. Each of them was converted into diosgenyl 2-amino-2-deoxy-beta-D-glucopyranoside hydrochloride (11) and N-acylamido derivatives. The structures of all new glycosides were established by 1H and 13C NMR spectroscopy. These diosgenyl glycosides are the first saponins containing the D-glucosamine residue that have been synthesized. These compounds show promising antitumor activities. The synthetic saponins increase the number of apoptotic B cells, in combination with cladribine (2-CdA), that are isolated from chronic lymphotic leukemia (B-CLL) patients.

Evaluation of apoptosis induced in vitro by cladribine (2-CdA) combined with anthracyclines in lymphocytes from patients with B-cell chronic lymphocytic leukemia

The aim of the study was to evaluate the effect of three anthracyclines [doxorubicin (DOX), mitoxantrone (MIT), and idarubicin (IDA)] on the rate of apoptosis triggered by 2-chlorodeoxyadenosine (2-CdA) in peripheral blood mononuclear cells isolated from 52 untreated patients with B-cell chronic lymphocytic leukemia (B-CLL). The cells were cultured up to 48 h in the presence of drugs alone and in the following combinations: 2-CdA+DOX, 2-CdA+MIT, and 2-CdA+IDA. Apoptosis was assessed after 24 h and 48 h of incubation using annexin V/propidium iodide assay by flow cytometry. The apoptotic index (AI) was defined as a percentage of annexin V-positive B-CLL cells. Additionally, in some patients other hallmarks of apoptosis (activation of caspases, DNA fragmentation) were assessed in parallel for confirmation of apoptotic mode of induced cell death. All of the cytostatics induced apoptosis of B-CLL cells at a rate significantly higher than the index of spontaneous apoptosis occurring during 24 h and 48 h of cell culture. 2-CdA in combination with DOX significantly increased the percentage of annexin V-positive cells, particularly after 48 h of incubation, as compared with DOX used in monotherapy (median AI for 2-CdA+DOX=37.9%, median AI for DOX =13.8%, P=0.0011, and median AI for 2-CdA=22.1%, P=0.013). Combination of 2-CdA with MIT induced a similar effect, also more distinct after 48 h (median AI for 2-CdA+MIT=41.05%, median AI for MIT=16.3%, p=0.0012, and median AI for 2-CdA=22.1%, p=0.017). For both combinations median AI were similar to the sum of median AI for each drug when used alone. IDA in a concentration ten times lower (0.1 micro g/ml) than used before in acute leukemia cells produced high cytotoxic effects, masking the additive effect of combination with 2-CdA. Only at a dose of 25 ng/ml of IDA, significant differences in AI after 24 h and 48 h were detected between samples treated with 2-CdA+IDA (median 27.5% and 65.0%, respectively) and those incubated with IDA alone (median 10.5% and 33.4%; P=0.0004 and 0.0274, respectively). Similarly, there were significant differences between AI of cells treated with 2-CdA+IDA and 2-CdA alone (median 9.5% at 24 h and 23.5% at 48 h; P=0.0013 and 0.0207, respectively). In conclusion; these data indicate an additive cytotoxic effect on B-CLL cells of DOX, MIT, and IDA applied in vitro with 2-CdA; all of them induced apoptosis with similar efficacy. We suggest that further preclinical and clinical studies concerning combined use of 2-CdA with anthracyclines are desirable. High sensitivity of B-CLL cells to IDA suggests the possibility of lowering its dose in patients, especially when combined with 2-CdA.

Some oncogene and tumour suppressor gene protein products expression in B-cell chronic lymphocytic leukaemia

The expression of Bcl-2, P53 proteins and known markers of proliferation, namely proliferating cell nuclear antigen (PCNA) and Ki67, in 29 patients with B-cell chronic lymphocytic leukaemia (B-CLL) was investigated. All leukaemic patients were classified, and immunophenotyped by the two-colour immunofluorescence method with the use of fluorocytometry. B-CLL was heterogeneous in the range of biological parameters of tumour cells. B-CLL patients manifested 34% positive Ki67 and 61% PCNA expression, whereas Bcl-2 and P53 positivity was 81% and 42%, respectively. The level of intracellular expression of Bcl-2 and P53 proteins did not depend on the stage of disease estimated by routine methods. Ki67 and PCNA expression was significantly higher in B-CLL patients with more advanced stages of the disease. A statistically significant correlation was established between their mutual expression.

Comparison of tin and lead toxic action on erythropoietic system in blood and bone marrow of rabbits

The aim of this work was to assess and compare morphological changes in blood and bone marrow of rabbits after per os (po) or intraperitoneal (ip) administration of equimolar doses of tin or lead. The experiment was performed on female rabbits that were divided into four groups of six animals each, and received stannous chloride SnCl2 x 2 H2O (Merck) or lead acetate Pb(CH3COO)2 (POCh Gliwice) in equimolar doses (ip--17/microM/kg) or per os (po--85/microM/kg). Group I was administered SnCl2 ip at the dose of 2 mg Sn/kg every day for 3 mo, group II Pb(CH3COO)2 ip at a dose of 3.5 mg Pb/kg every day for 3 wk, group III po SnCl2 (10 mg Sn/kg), and group IV po Pb(CH3COO)2 (17.5 mg Pb/kg), both for 4 mo. The morphological factors hemoglobin (Hb), hematocrit (Ht), erythrocyte (Ercs), and reticulocyte counts, MCV, MCH, MCHC, and erythropoietic system in bone marrow aspirates with sideroblast count, iron concentration, TIBC, and SI were estimated. Tin caused hemolytic anemia depending on abnormal iron utilization. After ip administration of tin, anemia was observed during the whole time of the study, whereas after po exposure, transient anemia was noticed. It has been proven that the mechanism of toxic action of tin on hematopoietic system is similar to the toxic effect of lead.