Cellular uptake mechanisms of an antitumor ruthenium compound: the endosomal/lysosomal system as a target for anticancer metal-based drugs.

Previous studies have described promising antitumor activity of an organometallic Ru(II) complex, η5-cyclopentadienyl(2,2'-bipyridyl)(triphenylphosphane) Ruthenium(II) triflate ([η5-C5H5)Ru(2,2'-bipyridyl)(PPh3)][CF3SO3]) herein designated as TM34. Its broad spectrum of activity against a panel of human tumor cell lines and high antiproliferative efficiency prompted us to focus on its mode of action. We present herein results obtained with two human tumor cell lines A2780 and MDAMB231 on the compound distribution within the cell, the mechanism of its activity, and its cellular targets. The prospective metallodrug TM34 revealed: (a) fast antiproliferative effects even at short incubation times for both cell lines; (b) preferential localization at the cell membrane and cytosol; (c) cellular activity by a temperature-dependent process, probably macropinocytosis; (d) inhibition of a lysosomal enzyme, acid phosphatase, in a dose-dependent mode; and (e) disruption and vesiculation of the Golgi apparatus, which suggest the involvement of the endosomal/lysosomal system in its mode of action. These results are essential to elucidate the basis for the cytotoxic activity and mechanism of action of this Ru(II)(η5-cyclopentadienyl) complex.

Activity of two enzymes associated with apoptosis and cell aging in arterial hypertension.

OBJECTIVE: To study the activity of two enzymes, transmembrane reductase (TMR) and cytosolic low molecular weight protein tyrosine phosphatase (ACP1), in arterial hypertension (HT) in a sample of adults aged over 50 years. METHODS: A sample of 153 adults, 77 with hypertension and 76 normotensive (NT), aged between 50 and 90 years (mean: 71.87 +/- 11.59), of both sexes, was studied. TMR (mmol/cell/h) and ACP1 (micromol/gHb/h) activity in red blood cells was determined by spectrophotometry. Statistical analysis was carried out using the Student's t test and Pearson's correlation. RESULTS: We observed a significant difference in TMR activity between normotensive and hypertensive subjects, with lower levels in the hypertensives (NT = 4.762 +/- 2.595; HT = 3.878 +/- 1.748), p = 0.01. ACP1 activity, although higher in hypertensive patients, did not differ significantly from normotensive subjects (p = 0.08) (NT = 242.827 +/- 97.618; HT = 309.561 +/- 150.738). No correlation was observed between the activity of the two enzymes in either the hypertensive or the normotensive group. CONCLUSIONS: The lower level of activity of transmembrane reductase in arterial hypertension may be implicated in cardiovascular aging processes, reinforced by greater cytosolic acid phosphatase activity, with repercussions on cell proliferation and energy metabolism, leading to atherosclerosis.

[Erythrocytic acid phosphatase genetic polymorphism and cardiovascular risk in health children and adolescents]. / Polimorfismo genético da Fosfatase Acida do eritrócito e risco cardiovascular em crianças e adolescentes saudáveis.

OBJECTIVE: To correlate, in a sample of healthy children and adolescents, the activity of the enzyme acid phosphatase (ACP) with its different genetic phenotypes and of these with some cardiovascular risk parameters such as body mass index (BMI), percentage of total fat mass (%TFM), trunk fat (TF), insulin resistance, and the arterial blood pressure (BP). DESIGN AND METHODS: The sample was composed of 173 healthy children and adolescents, 96 (55.5%) F and 77 (44.5%) M, with ages between 10 and 16 years (mean: 13.04 +/- 1.68). The ACP activity was determined through a spectrophotometric method and its phenotypes through isoelectric focusing electrophoresis. BMI (Kg/m2) and the BP were obtained by standardized methods. Glycemia determined by the glucose oxidase method and insulinemia by RIA method. Insulin resistance based on the homeostasis model assessment (HOMA) was calculated as: [fasting insulin (microU/ml) x fasting glucose (mmol/l)]: 22.5. The %TFM and TF were determined by dual energy x-ray absorptiometry (DXA). The statistical methods used were ANOVA, the Pearson correlation and the Student's test. RESULTS: The distribution of the phenotypes were the following--absolute versus relative frequencies: BB-74 (48.4%), AB-52 (34%), AA-16 (10.5%), BC-7 (4.6%), AC-3 (2%) and CC-1 (0.7%). ACP activities (mean: 321.04 +/- 84.56) were significantly different among the phenotypes (p < 0.001). The smallest activity was observed in the AA individuals, the highest in CC, followed by BC (247.17 +/- 66.52 and 767.30 and 362.44 +/- 91.56 respectively). Glycemia was higher in the AA individuals (4.61 +/- 0.37) compared to CC + BC (4.40 +/- 0.31) (p = 0.08). A direct correlation was verified between HOMA and BP, both diastolic (p = 0.013, r = 0.250) and systolic (p = 0.015, r = 0.246), as well as of these with BMI (mean: 20.57 +/- 3.24) and insulinemia (p = 0.016, r = 0.215; p = 0.004, r = 0.280 and p = 0.007, r = 0.240; p = 0.008, r = 0.261 respectively for diastolic and systolic BP). There were no significant difference of BMI between sexes, nor of this as well as of % TFM and TF among the different genetic phenotypes of ACP. CONCLUSIONS: The smallest enzymatic activity of ACP seems to be associated with the AA individuals, where a trend for higher glycemia was verified. BMI, HOMA and insulinemia, due to their significant direct relationship with diastolic and systolic BP in this sample of children and adolescents may warrant more future attention in the evaluation of cardiovascular risk. There were no significant differences of HOMA, BMI, %TFM, TF nor of BP among the different ACP genetic phenotypes.