Encapsulation of adriamycin in human erythrocytes.

Flora, Antonio De; Benatti, Umberto; Guida, Lucrezia; Zocchi, Elena

doi:10.1073/pnas.83.18.7029

Cited by 39 publications

(9 citation statements)

References 28 publications

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“…We used the resealing procedure described in [12] with modifications [13]. This procedure included three steps: hypotonic lysis; recovery of swollen cells; and isotonic resealing.…”

Section: Methodsmentioning

confidence: 99%

Influence of Osmotic Stress on Protein Methylation in Resealed Erythrocytes

Ingrosso

Cotticelli

D’Angelo

et al. 1997

European Journal of Biochemistry

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Resealed erythrocytes are a useful means of targeting exogenous proteins or extending their activity. We tested human resealed erythrocytes as a model system for studying protein methyl esterification, a reaction involved in the processing of spontaneously deamidatedhsomerized polypeptides. Our results show that resealed erythrocytes are still active in the metabolic processes that lead to the formation of methyl-esterified proteins. The methylation pattern of endogenous membrane proteins appeared to be similar to that of normal erythrocytes, with bands 2.1, 3, 4.1 and 4.2 as the major methyl acceptors. We detected methyl esterification of ovalbumin, as an exogenous substrate trapped within resealed erythrocytes. Methyl incorporation was almost completely inhibited by siinultaneously loading red cells with adenosine and homocysteine thiolactone, in vivo precursors of the transmethylation inhibitor S-adenosylhomocysteine. We investigated the effects of repeated resealing procedures on methyl acceptability of endogenous membrane proteins. We found that methyl-incorporation levels increased, despite an apparent conserved protein composition of the membrane. This result suggests that osmotic stress to the membrane may be responsible for increased protein methylation due to the appearance of new sites or an increased accessibility of existing sites.Keywords: protein methylation; osmotic stress ; erythrocyte resealing; protein deamidation and repair; erythrocyte membrane.Protein-L-isoaspartate (D-aspartate) 0-methyltransferase (PCMT) is a ubiquitous enzyme, with particularly high specific activity in mature human erythrocytes. It catalyzes the S-adenosylmethionine (AdoMet)-dependent methyl esterification of proteins and peptides at the level of L-isoaspartyl (and D-aspartyl) residues [ 1-31, These specific protein fatigue-damaged residues spontaneously result from asparaginyl deamidation or aspartyl racemization during protein aging [I, 41. In vitro studies have shown that PCMT initiates the repair of such damaged proteins [5, 61. This function is expected to be crucial in mature red blood cells (RBC), which are no longer able to replace age-damaged defective protein molecules, since de novo protein synthesis is absent. This proposal is consistent with the notion that the methyl-accepting capability of erythrocyte-membrane proteins increases as red cells age in circulation 171. More recently, it has been shown that methylation levels of RBC-membrane proteins increase in hereditary spherocytosis concomitantly with the degree of cytoskeletal derangement [S].RBC can be reversibly lysed and resealed, entrapping exogenous compounds, including proteins and peptides [ 121. Encapsulation in carrier RBC has been proposed as an effective way of extending the pharmacological activity or reducing the toxicity of drugs [9] or of prolonging enzyme activity in vivo [lo]. In Corresponderzcr to D. Ingrosso, Tstituto di Biochiinica delle Macromolecole, Facolta di Medicina e Chirurgia, Seconda Universiti di Napoli, via Cobtantinopolj,...

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“…We used the resealing procedure described in [12] with modifications [13]. This procedure included three steps: hypotonic lysis; recovery of swollen cells; and isotonic resealing.…”

Section: Methodsmentioning

confidence: 99%

Influence of Osmotic Stress on Protein Methylation in Resealed Erythrocytes

Ingrosso

Cotticelli

D’Angelo

et al. 1997

European Journal of Biochemistry

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“…Recently, encapsulation of adriamycin in human erythrocytes has been suggested [11] as a new therapeutic approach allowing the slow release of a drug in the circulation. In our opinion, the ability Table 1 The maximal yield of the carminomycin semiquinone during anaerobic NAD(P)H-dependent reduction of the antibiotic by human membranes …”

Section: Resultsmentioning

confidence: 99%

One‐electron reduction of an anthracycline antibiotic carminomycin by a human erythrocyte redox chain

Peskin

Bartosz

1987

FEBS Letters

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Human erythrocyte membranes catalyse the NAD(P)H-dependent generation of the semiquinone of an adriamycin-type antibiotic carminomycin under anaerobic conditions. The maximal yield of the antibiotic radical is about 4-fold higher in the presence of NADPH than of NADH. The possible significance of the antibiotic reduction to the semiquinone by a human erythrocyte membrane redox chain for the clinical usage of these antibiotics is discussed.

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“…In relation to human (4,6,11) or other mammalian species erythrocytes (9,17,27,31), rat erythrocytes incorporate a lower fraction of the total marker substance present in the medium (26). Nonetheless, due to lower cell recovery, the amount of substance encapsulated per cell is similar in both rat and human species and, therefore, rat erythrocytes could be considered as a potential carrier system in the case of an active drug being encapsulated (1,26).…”

Section: Resultsmentioning

confidence: 99%

Fluorescence analysis of carrier rat and human erythrocytes loaded with FITC-dextran

Álvarez¹,

Herráez²,

Tejedor³

1996

Cytometry

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Rat and human erythrocytes are inherently different with respect to slow dialysis encapsulation used in preparing carrier erythrocytes. The incorporation process, commonly measured with radioactive tracers, is always larger in human erythrocytes, mainly because the rat carrier cells are more fragile. When FITC‐Dextran (Dx) is used in the encapsulation process, and loaded rat and human RBCs are studied by fluorescence intensity, some additional events are evident. Not all cells of each population appear with a fluorescence signal, and not all show similar fluorescence intensity. Human RBCs show a higher percentage of marked cells and a higher fluorescence intensity than rat RBCs. Two populations, of high and low fluorescence, appear in FITC‐Dx loaded rat erythrocytes. The human loaded RBCs show a similar peak distribution together with another peak in the middle scale of fluorescence. Therefore, a heterogeneity in the cell population as a result of the encapsulation process is manifested for both species. The fractionation of RBCs, loaded with either FITC‐Dx or 125I‐CA, by centrifugation on Ficoll‐Paque reveals that the low density cells have much more substance incorporation than the counterpart cell subpopulation in the pellet. Therefore, the cell modifications produced by the encapsulation process are independent of the substance being incorporated. On the other hand, FITC‐Dx, but not 125I‐CA, shows a certain degree of association to RBCs membranes, especially in humans. © 1996 Wiley‐Liss, Inc.

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Encapsulation of adriamycin in human erythrocytes.

Cited by 39 publications

References 28 publications

Influence of Osmotic Stress on Protein Methylation in Resealed Erythrocytes

Influence of Osmotic Stress on Protein Methylation in Resealed Erythrocytes

One‐electron reduction of an anthracycline antibiotic carminomycin by a human erythrocyte redox chain

Fluorescence analysis of carrier rat and human erythrocytes loaded with FITC-dextran

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