Improved metastasis-free survival in nonadjuvantly treated postmenopausal breast cancer patients with chemokine receptor 5 del32 frameshift mutations.

The CC-chemokine receptor CCR5 has been associated with cancer progression and metastasis. CCR5 blockers such as Maraviroc are tested in metastatic cancer patients. A mutant allele of CCR5, CCR5-delta32 (CCR5del32), which encodes for a protein with a trans-dominant negative effect on the wildtype protein, is frequently found in populations of northern European origin. We set out to determine if the CCR5del32 genotype is associated with progression of breast cancer. Here, we genotyped 414 breast cancer patients and investigated whether the CCR5 genotype had an association with the likelihood to metastasize within specific subgroups of this cohort. The findings were subsequently confirmed in an independent cohort of 1,017 breast cancer patients. Specifically within the postmenopausal subgroup of the initial cohort (n = 325) individuals carrying the CCR5del32 genotype exhibited a significantly longer metastasis-free survival (MFS, p = 0.038). In an independent cohort, CCR5del32 genotype was confirmed to be associated with prolonged MFS only in postmenopausal patients (n = 579, hazard ratio [HR] = 0.61, 95% confidence interval [95% CI] = 0.38-0.99, p = 0.044), and not in premenopausal patients (n = 438, HR = 1.01, 95% CI = 0.70-1.48, p = 0.94). Our results indicate that CCR5del32 genotype is associated with good prognosis in postmenopausal breast cancer patients. Considering this result, postmenopausal breast cancer patients who are wildtype for CCR5 genotype might benefit from CCR5 blockers, such as Maraviroc.

HIV-1 subtype C syncytium- and non-syncytium-inducing phenotypes and coreceptor usage among Ethiopian patients with AIDS.

OBJECTIVE: To assess syncytium-inducing (SI) and non-syncytium-inducing (NSI) frequencies, coreceptor usage and gp120 V3 sequences of HIV-1 isolates from Ethiopian AIDS patients. PATIENTS: Cross-sectional study on 48 hospitalized AIDS patients (CD4 T cells < 200 x 10(6) cell/l) with stage III or IV of the WHO staging system for HIV-1 infection and disease. METHODS: Peripheral blood mononuclear cells (PBMC) from all 48 patients were tested by MT-2 assay to determine SI/NSI phenotypes. Lymphocyte subsets were enumerated using Coulter counting and FACScan analysis. Viral load determination used a nucleic acid sequence-based amplification assay (NASBA). Coreceptor usage of HIV-1 biological clones was measured using U87 CD4/chemokine receptor transfectants and phytohemagglutinin-stimulated PBMC of healthy donors with wild-type CCR5 and homozygous mutation CCR5delta32 (a 32 base-pair deletion in CCR5). Reverse transcriptase polymerase chain reaction sequencing was performed on the third variable region (V3) of the HIV-1 gene gp120. Sequence alignments were done manually; phylogenetic analyses used PHYLIP software packages. RESULTS: SI viruses were detected for 3/48 (6%) AIDS patients only. Lower mean absolute CD4 counts were determined in patients with SI virus compared with NSI (P = 0.04), but no differences in viral load were observed. All patients were found to be infected with HIV-1 subtype C, based on V3 sequencing. NSI biological clones used CCR5 as coreceptor; SI biological clones used CXCR4 and/or CCR5 and/or CCR3. CONCLUSIONS: Ethiopian patients with HIV-1 C-subtype AIDS harbour a remarkably low frequency of SI phenotype viruses. Coreceptor usage of these viruses correlates with their biological phenotypes.

Timing of the HIV-1 subtype C epidemic in Ethiopia based on early virus strains and subsequent virus diversification.

OBJECTIVE: To trace the introduction of HIV-1 subtype C into Ethiopia based on virus diversification during the epidemic. DESIGN: A set of 474 serum samples obtained in Ethiopia in 1982-1985 was tested for HIV-1. HIV-1 env gp120 V3 and gag or pol regions were sequenced and analysed together with sequences from later stages of the epidemic. RESULTS: None of 98 samples from 1982-1983, one of 193 samples from 1984, and one of 183 samples from 1985 were HIV-1 positive. Phylogenetic analysis of virus sequences from positive samples revealed that they belong to the Ethiopian C, and not the C', cluster. Analysis of 81 Ethiopian C V3 sequences from 1984-1997 revealed that the consensus sequence of the Ethiopian epidemic has been stable over time. Both the 1984 and 1985 V3 sequences, in contrast with three out of 27 (11%) of the 1988 and none out of 51 of the 1992-1997 sequences, had no synonymous substitutions compared to the reconstructed common ancestor of the Ethiopian C viruses. A highly significant correlation between sampling years of the V3 sequences and their synonymous distances to the common ancestor was demonstrated. CONCLUSIONS: The increasing genetic heterogeneity together with stable consensus sequence of the Ethiopian HIV-1 C population demonstrates that evolution of the virus population is characterized by an unbiased expansion around a stationary consensus. Based on the rate of synonymous diversification of HIV-1 strains within the Ethiopian population, we were able to estimate 1983 (95% confidence interval, 1980-1984) as the year of HIV-1 C introduction into Ethiopia.

Role of the quinone structure in the mitochondrial damage induced by antitumor anthracyclines. Comparison of adriamycin and 5-iminodaunorubicin.

Adriamycin cardiotoxicity has been correlated with a disturbance of heart mitochondrial functions. Here, 5-iminodaunorubicin was compared with adriamycin for its capability to interfere in the mitochondrial electron transport with subsequent membrane damaging. The results suggest that minor chemical modifications of the anthraquinone moiety of anthracycline glycoside drugs should be a promising way to decrease mitochondrial membrane damage induced by this class of antitumor drugs.

Mitochondrial development in Trypanosoma brucei brucei transitional bloodstream forms.

Intermediate and short stumpy bloodstream forms of Trypanosoma brucei brucei are transitional stages in the differentiation of mammal-infective long slender bloodstream forms into the procyclic forms found in the midgut of the tsetse vector. Although the mitochondria of the proliferative long slender forms do not accumulate rhodamine 123, the mitochondria of the transitional forms attain this ability thus revealing the development of an electromotive force (EMF) across the inner mitochondrial membrane. The EMF is inhibited by 2,4-dinitrophenol, rotenone and salicylhydroxamic acid but not by antimycin A or cyanide. Consequently, NADH dehydrogenase, site I of oxidative phosphorylation, is the source of the EMF and the plant-like trypanosome alternative oxidase (TAO) supports the electron flow serving as the terminal oxidase of the chain. Although the TAO is present in the long slender forms as well, it serves only as the terminal oxidase for electrons from glycerol-3-phosphate dehydrogenase. The data presented here, combined with older data, lead to the conclusion that the mitochondria of transitional intermediate and short stumpy forms likely produce ATP. This putative production is either by F1F0 ATPase driven by the complex I proton pump or by mitochondrial substrate level phosphorylation, or most likely by both. These conclusions contrast with the previously held dogma that all bloodstream form mitochondria are incapable of ATP production.

Damages of the mitochondrial membrane in Adriamycin treated mice.

OF1 Swiss male and female mice received adriamycin (ADM) i.p. in increasing doses. Animals were killed after 2 or 4 days. Hearts were removed and mitochondria were isolated. ADM induced an inactivation of the respiratory enzymes closely related to an increase of the mitochondrial membrane viscosity and of the lipid peroxidation. Two ADM derivatives studied similarly did not produce these effects.

Identification of a genetic subcluster of HIV type 1 subtype C (C') widespread in Ethiopia.

Others and we have previously shown that subtype C is the predominant HIV-1 subtype and the major cause of AIDS in Ethiopia. The present study shows that subtype C in Ethiopia has a genetic subcluster, designated C', has not increased in frequency, or spread geographically, over the period 1988 (%C' = 23/53) to 1996-1997 (%C' = 26/50). There is no association of the HIV-1 subtype C or subcluster C' with geographic location, time of sample collection, or risk group in Ethiopia. Of 105 randomly collected samples representing 7 different towns in Ethiopia, all but 2 (1 subtype A from Addis Ababa, 1997 and 1 subtype D from Dessie, 1996) belong to subtype C.

Timing of the introduction into Ethiopia of subcluster C' of HIV type 1 subtype C.

Viruses circulating in Ethiopia during the 1990s cluster with main subtype C, but a significant subcluster, C', was noted in multiple analyses. This subcluster of subtype C(C') was in a fifty-fifty equilibrium with the main subtype C (Abebe et al., AIDS Res Hum Retroviruses 2000;16:1909-1914). To analyze genetic diversification within the subcluster of HIV-1 subtype C designated C' in the course of the epidemic in Ethiopia, we analyzed 165 env gp120 V3 sequences obtained between 1988 and 1999. We observed a highly significant positive correlation between sampling years of individual sequences and their synonymous distances to the reconstructed common ancestor of the HIV-1 subtype C' subcluster. The extrapolation of the regression line of synonymous distances back to the date when no synonymous heterogeneity was present among the Ethiopian HIV-1 C' population allowed us to estimate 1982 (95% CI, 1980-1983) as the year of the onset of HIV-1 C' genetic diversification and expansion in Ethiopia. These results are in agreement with retrospective epidemiological and serological data, which demonstrated the absence of an HIV-1 epidemic in the Ethiopian population before the 1980s.

Mitochondrial membrane modifications induced by adriamycin-mediated electron transport.

Adriamycin (ADM) was found to have a two-step mode of action on the cardiac mitochondrial membrane. (1) An interaction with cardiolipin (CL) resulted in the formation of an ADM-CL complex able to transfer electrons from NADH to cytochrome c (cyt.c) as well as coenzyme Q (CoQ). This complex formation stimulates an increased activity of NADH-CoQ oxidoreductase (complex I) and CoQ-cyt.c oxidoreductase (complex III). (2) Transfer of electrons through ADM resulted in the formation of a very strong complex between ADM and CL. This new complex is different and much stronger than the already known ADM-CL complex.

In vivo and in vitro modifications of the mitochondrial membrane induced by 4' Epi-adriamycin.

Mice received 4' Epi-adriamycin (4' Epi-ADM) i.p. in increasing doses. After 48 hours, hearts were removed and mitochondria were isolated. 4' Epi-ADM had no effect on the enzymatic activities of complexes I-III and complex IV of the mitochondrial respiratory chain; no modification of the mitochondrial membrane viscosity was observed and only a slight membrane lipid peroxidation was measured. On the contrary, in vitro studies showed a 4' Epi-ADM dependent enzymatic inactivation of complex I-III and IV, correlated with a mitochondrial membrane rigidification and an enhanced lipid peroxidation rate.

Competition between inhibitors of the trypanosome alternative oxidase (TAO) and reduced coenzyme Q9.

The trypanosome alternative oxidase (TAO) is an attractive target for chemotherapy for the diseases caused by African trypanosomes because there is no equivalent enzyme in mammalian hosts. Many inhibitors of this enzyme have been described, but there have been no data on the mechanism of inhibition. In the present study, reduced 2,3-dimethoxy-5-methyl-6-decyl-1,4-benzoquinone (decyl-CoQ-H2) was used as a substitute for the natural substrate CoQ9-H2 to allow direct measurements of the TAO in crude mitochondrial preparations from Trypanosoma brucei brucei. A Km value of 3.8 microM was obtained for this substrate. The following five compounds that have alkyl side chains from 1 to 4 carbons and belong to three classes of inhibitors showed a competitive inhibition pattern with respect to decyl-CoQ-H: p-methoxybenzhydroxamic acid, p-ethoxybenzhydroxamic acid,p-n-butyloxybenzhydroxamic acid, methyl 3,4-dihydroxybenzoate and N-n-butyl-3,4-dihydroxybenzamide. The following four compounds belonging to the same chemical classes but having alkyl side chains from 10 to 12 carbons showed uncompetitive inhibition patterns: p-n-dodecyloxybenzhydroxamic acid, n-decyl 3,4-dihydroxybenzoate, n-dodecyl 3,4-dihydroxybenzoate, and N-n-decyl-3,4-dihydroxybenzamide. Clearly, the first group of inhibitors compete with CoQ-H2 for the active site of the TAO. We propose that the uncompetitive patterns produced by the second group of inhibitors are due to the greater lipophilicity of these compounds and the resulting change in the interaction of the inhibitors and the membrane containing the TAO, thus affecting the local concentration of the inhibitors at the active site.

A new class of free radical scavengers reducing adriamycin mitochondrial toxicity.

Beef heart mitochondria were incubated with ADM and NADH. An adriamycin semiquinone radical was detected using ESR spectroscopy. The semiquinone radical production rate is decreased upon addition of a scavenger (AD 20) in the reaction medium. NMRI mice were treated with AD 20 (70 mg/kg, i.p.) 15 min prior ADM injection (20 mg/kg, i.p.) or with ADM alone. Heart mitochondria were isolated 48 hr later. The enzymatic activities of complex I-III and complex IV of the mitochondrial respiratory chain were strongly depressed in animals receiving ADM alone, whereas these activities were almost completely restored in animals receiving AD 20 and ADM. Fluorescence depolarization measurements indicated that only mice treated with ADM alone presented a decreased fluidity of their cardiac mitochondrial membrane.

Non-cytochrome mediated mitochondrial ATP production in bloodstream form Trypanosoma brucei brucei.

The life cycle of Trypanosoma brucei brucei involves a series of differentiation steps characterized by marked changes in mitochondrial development and function. The bloodstream forms of this parasite completely lack cytochromes and have not been considered to have any Krebs cycle function. It has been suggested that glycolysis is the sole source of ATP in all bloodstream forms. However, earlier results indicated that in the mitochondria of the transitional intermediate/short stumpy bloodstream forms, the biochemical pathways are present that could allow intra-mitochondrial production of ATP. Using a high mannitol buffer to enhance permeability, we confirm previous observations showing that transitional forms maintain motility and respiratory activity with 2-oxoglutarate as the sole substrate. Using a luminometer to measure intracellular ATP levels via the luciferin/luciferase chemiluminescence assay, we show that these same transitional forms, but not long slender forms, maintain high levels of intracellular ATP in the presence of 2-oxoglutarate. Further, in the presence of bongkrekic acid, an inhibitor of the mitochondrial adenine nucleotide translocase, ATP levels are reduced with subsequent death and lysis of the cells when 2-oxoglutarate, but not glucose, is used as sole substrate. These data are direct evidence of ATP production by transitional bloodstream form mitochondria.

Trypanocidal CoQ analogues: their effect on other mitochondrial systems.

1. A comparative study of compounds which inhibit the respiration of the infective form of the protozoan parasite Trypanosoma brucei brucei, such as salicylhydroxamic acid, other substituted benzhydroxamic acid, esters of 2,3- and 3,4-dihydroxybenzoic acid and structurally related compounds, showed that they have a remarkable degree of selectivity for the trypanosome as compared to rat liver mitochondria even though they are putative CoQ analogues and both respiratory systems are dependent on CoQ. 2. The minimal inhibition of mammalian mitochondrial function could not be assigned to inhibition of ubiquinone function in these mitochondria. 3. CoQ-reducing mitochondrial dehydrogenases from rat liver, trypanosomes and skunk cabbage (Symplocarpus foetidus) were insensitive to these inhibitors. 4. The alternative oxidase of skunk cabbage mitochondria was sensitive to a spectrum of trypanosome respiration inhibitors suggesting a similarity to the oxidase of the trypanosome although differing degrees of sensitivity and differing responses to alterations in the molecular structure of the inhibitors indicate that the milieu of the active sites are dissimilar.

Adriamycin and derivatives interaction with the mitochondrial membrane: O2 consumption and free radicals formation.

Adriamycin induces the formation of semiquinone free radicals, O(2) and OH. species, in beef heart intact mitochondria, submitochondrial particles and complex I-III containing proteoliposomes. Free radicals were detected by the use of Electron Spin Resonance (ESR) spectroscopy with the spin trapping method. However, to observe transient oxygen species in intact mitochondria, a flow technique was mandatory. ESR results were compared with oxygen consumption measurements. Since free radicals could be involved in the mechanism of the adriamycin induced cardiotoxicity, it was essential to design new adriamycin derivatives which do not generate radicals. From the study of two adriamycin analogs (N-acetyl-adriamycin and 5-Iminodaunorubicin), it was shown that oxygen radicals formation require both the binding of the drug to the mitochondrial membrane and a quinone function associated with the drug structure. The data reported here might be useful in the synthesis of less cardiotoxic compounds.

N-linked glycosylation of the HIV type-1 gp120 envelope glycoprotein as a major determinant of CCR5 and CXCR4 coreceptor utilization.

The variable V1V2 and V3 regions of the human immunodeficiency virus type-1 (HIV-1) envelope glycoprotein (gp120) can influence viral coreceptor usage. To substantiate this we generated isogenic HIV-1 molecularly cloned viruses that were composed of the HxB2 envelope backbone containing the V1V2 and V3 regions from viruses isolated from a patient progressing to disease. We show that the V3 amino acid charge per se had little influence on altering the virus coreceptor phenotype. The V1V2 region and its N-linked glycosylation degree were shown to confer CXCR4 usage and provide the virus with rapid replication kinetics. Loss of an N-linked glycosylation site within the V3 region had a major influence on the virus switching from the R5 to X4 phenotype in a V3 charge-dependent manner. The loss of this V3 N-linked glycosylation site was also linked with the broadening of the coreceptor repertoire to incorporate CCR3. By comparing the amino acid sequences of primary HIV-1 isolates, we identified a strong association between high V3 charge and the loss of this V3 N-linked glycosylation site. These results demonstrate that the N-linked glycosylation pattern of the HIV-1 envelope can strongly influence viral coreceptor utilization and the R5 to X4 switch.

Respiration of bloodstream forms of the parasite Trypanosoma brucei brucei is dependent on a plant-like alternative oxidase.

CoQ links the sn-glycerol-3-phosphate dehydrogenase and oxidase components of the cyanide-insensitive, non-cytochrome-mediated respiratory system of bloodstream African trypanosomes. In this and other characteristics, their respiratory system is similar to the alternative oxidase of plants. The parasites contain 206 ng of CoQ9 mg protein-1 which co-sediments with respiratory activity. The redox state of this CoQ responds in a manner consistent with respiratory function: 60% being in the reduced form when substrate is available and the oxidase is blocked; 13% being in the reduced form when the oxidase is functioning and there is no substrate. The addition of CoQ to aceton-extracted cells stimulates salicylhydroxamic acid-sensitive respiration by 56%. After inhibition of respiration by digitonin-mediated dispersal of the electron transport components, liposomes restore 40% of respiratory activity while liposomes containing CoQ restore 66% of this activity. A less hydrophobic analogue, reduced decyl CoQ, serves as a direct substrate for the trypanosome oxidase supporting full salicylhydroxamic acid-sensitive respiration. After digitonin disruption of electron transport, the nonreduced form of this synthetic substrate can reestablish the chain by accepting electrons from dispersed sn-glycerol-3-phosphate dehydrogenase and transferring them to the dispersed oxidase. Similarities between the alternative oxidase of plants and the oxidase of the trypanosome respiratory system include: mitochondrial location, lack of oxidative phosphorylation, linkage of a dehydrogenase and an oxidase by CoQ, lack of sensitivity to a range of mitochondrial inhibitors, and sensitivity to a spectrum of inhibitors which selectively block transfer of electrons from reduced CoQ to the terminal oxidase but do not block electron transfer to the cytochrome bc1 complex of the mammalian cytochrome chain.

HIV-1 subtype C in commerical sex workers in Addis Ababa, Ethiopia.

In this study, we have investigated the diversity of the current HIV-1 strains circulating in Addis Ababa, Ethiopia; in addition, we have evaluated the applicability of peptide enzyme-linked immunosorbent assay (ELISA) and heteroduplex mobility assay (HMA) for HIV-1 subtyping. Previous studies have indicated that HIV-1 subtype C is the major subtype present in HIV-positive samples collected from various risk groups between 1988 and 1995 in Addis Ababa. To assess the possible influx of new HIV-1 subtypes, 150 commercial sex workers (CSW) reporting in 1997 to two Health Centers in Addis Ababa were enrolled in an unlinked anonymous cross-sectional study. Subtyping was performed according to the World Health Organization algorithm of peptide ELISA, followed by HMA and DNA sequencing. As a result, the HIV-1 prevalence among these CSWs was found to be 45% (67 of 150). Of the 67 samples, 66 contained HIV-1 of subtype C and only one was of subtype D. This confirms the persistent overall presence of HIV-1 subtype C in Addis Ababa and a low influx of other subtypes into this location.

Apelin, the natural ligand of the orphan seven-transmembrane receptor APJ, inhibits human immunodeficiency virus type 1 entry.

In addition to the CCR5 and CXCR4 chemokine receptors, a subset of primary human immunodeficiency virus type 1 (HIV-1) isolates can also use the seven-transmembrane-domain receptor APJ as a coreceptor. A previously identified ligand of APJ, apelin, specifically inhibited the entry of primary T-tropic and dualtropic HIV-1 isolates from different clades into cells expressing CD4 and APJ. Analysis of apelin analogues demonstrated that potent and specific antiviral activity was retained by a 13-residue, arginine-rich peptide. Antiviral potency was influenced by the integrity of methionine 75, which contributes to APJ-binding affinity, and by the retention of apelin residues 63 to 65. These studies demonstrate the ability of a small peptide ligand to block the function of APJ as an HIV-1 coreceptor, identify apelin sequences important for the inhibition, and provide new reagents for the investigation of the significance of APJ to HIV-1 infection and pathogenesis.