Experimental study of pelvic perioperative brachytherapy with iodine 125 seeds (I-125) in an animal model.

PURPOSE: The aim of this study is to investigate the feasibility of perioperative I-125 low-dose-rate brachytherapy mesh implantation in pelvic locations in an animal model, before applying it clinically. MATERIAL AND METHODS: The animal model was the Romanov adult ewe. Non-radioactive dummy I-125 seeds were implanted by laparotomy in the pelvic area. Forty-five dummy seeds were placed on a 10 cm² polyglactin mesh to obtain a dose of 160 Gy at 5 mm from the center of each seed. Three CT scans were performed at day 15, day 70, and day 180 after surgery to check the positioning of the mesh for eventual seed migration according to bony landmarks and to perform a 3D theoretical dosimetric study. The experimental study design was based on Simon's minimax plan with a preliminary analysis of 10 ewes to validate the protocol and a second series of 7 ewes. RESULTS: After the first step, 9 of 10 ewes were investigated. For 8 of 9 animals, the 160 Gy isodose line volume was within 10%, showing feasibility of the procedure and allowing 7 more to be added. At the end of the study, 16 of 17 animals were examined. No seeds loss was observed. The volume difference of the 160 Gy isodose line was within 10% in 13 of 16 ewes between the three CT scans. Twelve out of 16 had a coordinate deviation less than or equal to 10 mm on the three axes between the first and the third scans. CONCLUSIONS: These results show the technical feasibility of the pelvic mesh implantation in ewes. A phase I study for patients with locally advanced or recurrent pelvic tumors amenable to surgery, in combination with surgical resection should be possible.

Histone H2B ubiquitination: signaling not scrapping.

Monoubiquitination of histone H2B has emerged as an important chromatin modification with roles not only in transcription but also in cell differentiation, DNA repair or mRNA processing. Recently, the genome-wide distribution of histone H2B ubiquitination in different organisms has been reported. In this review we discuss the mechanisms regulating H2B ubiquitination and its downstream effectors as well as the suggested functions for this mark in light of these recent studies.:

Preclinical evidence that SSR128129E--a novel small-molecule multi-fibroblast growth factor receptor blocker--radiosensitises human glioblastoma.

Resistance of glioblastoma to radiotherapy is mainly due to tumour cell radioresistance, which is partially controlled by growth factors such as fibroblast growth factor (FGF). Because we have previously demonstrated the role of FGF-2 in tumour cell radioresistance, we investigate here whether inhibiting FGF-2 pathways by targeting fibroblast growth factor receptor (FGFR) may represent a new strategy to optimise the efficiency of radiotherapy in glioblastoma. Treating radioresistant U87 and SF763 glioblastoma cells with the FGFR inhibitor, SSR12819E, radiosensitises these cells while the survival after irradiation of the more radiosensitive U251 and SF767 cells was not affected. SSR128129E administration to U87 cells increases the radiation-induced mitotic cell death. It also decreased cell membrane availability of the FGFR-1 mainly expressed in these cells, increased this receptor's ubiquitylation, inhibited radiation-induced RhoB activation and modulated the level of hypoxia inducible factor, HIF-1α, a master regulator of hypoxia, thus suggesting a role of FGFR in the regulation of hypoxia pathways. Moreover, treating orthotopically U87 xenografted mice with SSR128129E before two subsequent local 2.5Gy irradiations significantly increased the animals neurological sign free survival (NSFS) compared to the other groups of treatment. These results strongly suggest that targeting FGFR with the FGFR blocker SSR128129E might represent an interesting strategy to improve the efficiency of radiotherapy in glioblastoma.

The human TREX-2 complex is stably associated with the nuclear pore basket.

In eukaryotes, mRNA export involves many evolutionarily conserved factors that carry the nascent transcript to the nuclear pore complex (NPC). The THO/TREX complex couples transcription to mRNA export and recruits the mRNA export receptor NXF1 for the transport of messenger ribonucleoprotein particles (mRNP) to the NPC. The transcription and export complex 2 (TREX-2) was suggested to interact with NXF1 and to shuttle between transcription sites and the NPC. Here, we characterize the dynamics of human TREX-2 and show that it stably associates with the NPC basket. Moreover, the association of TREX-2 with the NPC requires the basket nucleoporins NUP153 and TPR, but is independent of transcription. Differential profiles of mRNA nuclear accumulation reveal that TREX-2 functions similarly to basket nucleoporins, but differently from NXF1. Thus, our results show that TREX-2 is an NPC-associated complex in mammalian cells and suggest that it is involved in putative NPC basket-related functions.

The tightly controlled deubiquitination activity of the human SAGA complex differentially modifies distinct gene regulatory elements.

The multisubunit SAGA coactivator complex facilitates access of general transcription factors to DNA through histone acetylation mediated by GCN5. USP22 (ubiquitin-specific protease 22) was recently described as a subunit of the human SAGA complex that removes ubiquitin from monoubiquitinated histone H2B and H2A in vitro. Here we demonstrate an allosteric regulation of USP22 through multiple interactions with different domains of other subunits of the SAGA deubiquitination module (ATXN7, ATXN7L3, and ENY2). Downregulation of ATXN7L3 by short hairpin RNA (shRNA) specifically inactivated the SAGA deubiquitination activity, leading to a strong increase of global H2B ubiquitination and a moderate increase of H2A ubiquitination. Thus, SAGA is the major H2Bub deubiquitinase in human cells, and this activity cannot be fully compensated by other deubiquitinases. Here we show that the deubiquitination activity of SAGA is required for full activation of SAGA-dependent inducible genes. Interestingly, the reduction of the SAGA deubiquitination activity and the parallel increase in H2B ubiquitation at inducible target genes before activation do not induce aberrant gene expression. Our data together indicate that different dynamic equilibriums of H2B ubiquitination/deubiquitination are established at different gene regulatory elements and that H2B ubiquitination changes are necessary but not sufficient to trigger parallel activation of gene expression.

Retrospective analysis of local control and cosmetic outcome of 147 periorificial carcinomas of the face treated with low-dose rate interstitial brachytherapy.

PURPOSE: Skin cancer is the most common malignancy in white populations. We evaluated the local cure rate and cosmetic outcome of patients with basal cell carcinoma (BCC) or squamous cell carcinoma (SCC) of the face treated with low-dose rate brachytherapy. METHODS AND MATERIALS: Between February 1990 and May 2000, 147 facial carcinomas in 132 patients were treated by (192)Ir wire implantation. Side effects of brachytherapy were noted. Follow-up was 2 years or more. Locoregional recurrence-free survival (LRFS) and overall survival were recorded. Group A included patients treated by primary brachytherapy, and Group B included those treated after recurrence. RESULTS: A total of 121 carcinomas were BCCs (82.3%) and 26 were SCCs (17.7%); the median tumor size was 10 mm. Of the tumors, 86 (58.5%) were in men and 61 (41.5%) were in women; the median age was 71 years. Group A comprised 116 lesions (78.9%), and Group B, 31 (21.1%). There were 17 relapses (11.6%) after a median follow-up of 72 months: 12 local, 4 nodal, and 1 local and nodal. Locoregional-free survival was 96.6% at 2 years and 87.3% at 5 years. Five-year LRFS was 82.6% in men and 93.3% in women (p = 0.027). After adjustment for gender, LRFS was better after primary treatment than after recurrence (hasard ratio HR, 2.91; 95% confidence interval, 1.06-8.03; p = 0.039). Five-year LRFS was 90.4% for BCC and 70.8% for SCC (p = 0.03). There were no Grade 3 complications. CONCLUSIONS: Low-dose rate brachytherapy offers good local control and cosmetic outcome in patients with periorificial skin carcinomas, with no Grade 3 complications. Brchytherapy is more efficient when used as primary treatment.

Brachytherapy in lip carcinoma: long-term results.

PURPOSE: The aim of this study was to evaluate the effectiveness of low-dose-rate brachytherapy for local control and relapse-free survival in squamous cell and basal cell carcinomas of the lips. We compared two groups: one with tumors on the skin and the other with tumors on the lip. PATIENTS AND METHODS: All patients had been treated at Claudius Regaud Cancer Centre from 1990 to 2008 for squamous cell or basal cell carcinoma. Low-dose-rate brachytherapy was performed with iridium 192 wires according to the Paris system rules. On average, the dose delivered was 65 Gy. RESULTS: 172 consecutive patients were included in our study; 69 had skin carcinoma (squamous cell or basal cell), and 92 had squamous cell mucosal carcinoma. The average follow-up time was 5.4 years. In the skin cancer group, there were five local recurrences and one lymph node recurrence. In the mucosal cancer group, there were ten local recurrences and five lymph node recurrences. The 8-year relapse-free survival for the entire population was 80%. The 8-year relapse-free survival was 85% for skin carcinoma 75% for mucosal carcinoma, with no significant difference between groups. The functional results were satisfactory for 99% of patients, and the cosmetic results were satisfactory for 92%. Maximal toxicity observed was Grade 2. CONCLUSIONS: Low-dose-rate brachytherapy can be used to treat lip carcinomas at Stages T1 and T2 as the only treatment with excellent results for local control and relapse-free survival. The benefits of brachytherapy are also cosmetic and functional, with 91% of patients having no side effects.

Alphavbeta3/alphavbeta5 integrins-FAK-RhoB: a novel pathway for hypoxia regulation in glioblastoma.

The presence of hypoxic areas in glioblastoma is an important determinant in tumor response to therapy and, in particular, to radiotherapy. Here we have explored the involvement of integrins, up to now known as regulators of angiogenesis and invasion, in the regulation of tumor hypoxia driven from the tumor cell. We first show that hypoxia induces the recruitment of alpha(v)beta(3) and alpha(v)beta(5) integrins to the cellular membrane of U87 and SF763 glioblastoma cells, thereby activating the focal adhesion kinase (FAK). We then show that inhibiting alpha(v)beta(3) or alpha(v)beta(5) integrins in hypoxic cells with a specific inhibitor or with siRNA decreases the hypoxia-inducible factor 1alpha (HIF-1alpha) intracellular level. This integrin-dependent regulation of HIF-1alpha is mediated through the regulation of FAK, which in turn activates the small GTPase RhoB, leading to the inhibition of GSK3-beta. Furthermore, silencing this pathway in glioma cells of established xenografts dramatically reduces glioma hypoxia, associated with a significant decrease in vessel density. Our present results unravel a new mechanism of hypoxia regulation by establishing the existence of an alpha(v)beta(3)/alpha(v)beta(5) integrin-dependent loop of hypoxia autoregulation in glioma. Targeting this hypoxia loop may be crucial to optimizing radiotherapy efficiency.

Alphavbeta3 and alphavbeta5 integrins control glioma cell response to ionising radiation through ILK and RhoB.

Integrins are extracellular matrix receptors involved in tumour invasion and angiogenesis. Although there is evidence that inhibiting integrins might enhance the efficiency of radiotherapy, little is known about the exact mechanisms involved in the integrin-dependent modulation of tumor radiosensitivity. The purpose of this study was to investigate the role of alphavbeta3 and alphavbeta5 integrins in glioblastoma cell radioresistance and overall to decipher the downstream biological pathways. We first demonstrated that silencing alphavbeta3 and alphavbeta5 integrins with specific siRNAs significantly reduced the survival after irradiation of 2 glioblastoma cell lines: U87 and SF763. We then showed that integrin activity and integrin signalling pathways controlled the glioma cell radiosensitivity. This regulation of glioma cell response to ionising radiation was mediated through the integrin-linked kinase, ILK, and the small GTPase, RhoB, by two mechanisms. The first one, independent of ILK, consists in the regulation of the intracellular level of RhoB by alphavbeta3 or alphavbeta5 integrin. The second pathway involved in cell radiosensitivity consists in RhoB activation by ionising radiation through ILK. Furthermore, we demonstrated that the alphavbeta3/alphavbeta5 integrins/ILK/RhoB pathway controlled the glioma cells radiosensitivity by regulating radiation-induced mitotic cell death. This work identifies a new biological pathway controlling glioblastoma cells radioresistance, activated from the membrane through alphavbeta3 and/or alphavbeta5 integrins via ILK and RhoB. Our results are clues that downstream effectors of alphavbeta3 and alphavbeta5 integrins as ILK and RhoB might also be promising candidate targets for improving the efficiency of radiotherapy and thus the clinical outcome of patients with glioblastoma.

Initiation of DNA replication by a third parallel DNA strand bound in a triple-helix manner leads to strand invasion.

According to current knowledge, DNA polymerases accommodate only two polynucleotide strands in their catalytic site: the template and the primer to be elongated. Here we show that in addition to these two polynucleotide strands, HIV-1 and AMV reverse transcriptases, human DNA polymerases beta, gamma, and lambda, and the archaebacterial Dpo4 can elongate 10-nucleotide primers bound in a triple-helix manner to hairpin duplex DNA tethered by a few thymidine residues. The elongation occurs when the primer is parallel to the homologous strand. This feature was confirmed by using complementary single-stranded DNA with restricted nucleotide composition which bound polypurine and polypyrimidine primers at an asymmetric site. The results unambiguously confirmed the previous experiments, showing binding of the primer strand parallel to the homologous sequence. The common feature of these DNA polymerases is that they all elongated dG-rich primers, whereas they behaved differently when other polynucleotide sequences were used. Interestingly, only five to seven dG residues at similar positions between the primer and its binding site can allow elongation, which may even be facilitated by a single C/C mismatch. We suggest that DNA polymerases displace the primer form Hoogsteen bonds to from Watson-Crick pairings, enabling subsequent priming of replication. These experiments indicate that DNA polymerases may bind three DNA strands, as RNA polymerases do, and provide a molecular basis for 3'-OH invasion at short similar sequences in the DNA double helix, yielding potential DNA rearrangements upon single-strand breakage.

Functional study of the 830C>G polymorphism of the human carboxylesterase 2 gene.

PURPOSE: Carboxylesterase 2 (CES2) is involved in the activation of the anticancer drug irinotecan to its active metabolite SN-38. We previously identified a single nucleotide polymorphism (SNP), with an allele frequency around 10%, as possibly involved in enzyme expression (Clin Pharmacol Ther 76:528-535, 2004), which could explain the large individual variation in SN-38 disposition. METHODS: The 830C>G SNP, located in the 5' untranslated region of the gene, was analysed in various DNA samples extracted from: (1) the National Cancer Institute NCI-60 panel of human tumour cell lines; (2) a collection of 104 samples of normal tissue from colorectal cancer patients; (3) blood samples from a population of 95 normal subjects; (4) a collection of 285 human livers. CES2 genotypes were tentatively related to irinotecan cytotoxicity and CES2 expression in the NCI-60 panel; to response to treatment and event-free survival in colorectal cancer patients; and to CES2 expression and catalytic activity in subsets of the human liver collection. RESULTS: No significant relationship was found in the NCI-60 panel between CES2 830C>G genotype and irinotecan cytotoxicity or CES2 expression. No significant relationship was found between CES2 830C>G genotype and the toxicity and therapeutic efficacy (tumour response, event-free survival) of irinotecan in colorectal cancer patients. There was no significant relationship between CES2 830C>G genotype and CES2 expression and catalytic activity determined in a subset of genotype-selected liver samples. CONCLUSION: The 830C>G SNP of CES2 is unlikely to have significant functional consequences on CES2 expression, activity or function.

Autocrine expression of osteopontin contributes to PDGF-mediated arterial smooth muscle cell migration.

OBJECTIVE: Migration of smooth muscle cells (SMCs) from the media to the intima of arteries is involved in intimal thickening. The platelet-derived growth factor (PDGF) BB is recognized as a major migratory factor for arterial SMCs both in vitro and during neointima formation. Since PDGF acts in synergy with the matrix protein osteopontin (OPN) and also induces its expression, the present study was conceived to explore the role of the OPN produced in an autocrine fashion by PDGF-stimulated SMCs in the migration process and to define regulatory mechanisms of OPN expression. METHODS AND RESULTS: PDGF stimulation of quiescent rat aortic SMCs induced their migration (transfilter assays) and the increase of OPN expression (mRNA and protein assays). Blockade of either OPN expression by a specific short interference RNA (siRNA) or of its function by a blocking antibody decreased the PDGF-stimulated migration by about 70%, demonstrating that autocrine production and excretion of OPN are integral to the PDGF-induced SMC migration. In parallel, SMC stimulation by PDGF also activated the transcription factor CREB essentially through mitogen-activated protein kinase (MAPK) 1/2 and protein kinase A (PKA) pathways. Inhibition of either CREB expression (via siRNA) or function (via dominant-negative CREB) decreased both PDGF-induced SMC migration and OPN expression. SMC transfection with OPN promoter reporter constructs demonstrated that PDGF-induced OPN transcription is mediated by CREB binding to two functional sites of the OPN promoter: a CRE site located at -1403 and an AP-1 site located at -76. CONCLUSION: The present study demonstrates that the autocrine expression of OPN plays a major role in PDGF-induced SMC migration. It further shows that the transcription factor CREB, activated in PDGF-stimulated SMCs, plays a key role in PDGF-induced SMC migration, probably by regulating OPN expression.

Functional analysis of the gene expression profiles of colorectal cancer cell lines in relation to oxaliplatin and cisplatin cytotoxicity.

The objective was to relate the gene expression profiles of colorectal cancer cells in culture to the in vitro cytotoxicity of cisplatin and oxaliplatin. We studied the gene expression profiles of six human colorectal cancer cell lines, using the Atlas Plastic Human 8K Microarray from Clontech, and related it to the in vitro cytotoxicities of oxaliplatin and cisplatin obtained by inhibition of exponential growth of cells. We calculated the Pearson's coefficients of correlation (r) between gene expression and drug IC50. A functional analysis was performed using the Gene Ontology Consortium database. Results were validated on a series of representative genes by real-time quantitative PCR. Validation of the significance of the coefficients of correlation was also performed using a leave-one-out analysis. We identified 394 genes whose expression was significantly correlated (P<0.05) to oxaliplatin cytotoxicity and 40 with cisplatin cytotoxicity. Three major functions were preferentially involved in oxaliplatin activity: protein synthesis, cell energetics and response to oxidative stress. No significant correlation was observed between oxaliplatin or cisplatin cytotoxicity and the expression of genes involved in DNA repair, cell proliferation or cell adhesion. A strongly significant correlation was found between the microarray and the rt-PCR approaches (r=0.968, P<10(-6)). The leave-one-out analysis showed that the same functions still appeared significantly involved in the activity of both drugs. Based on the functional analysis, we hypothesized that oxaliplatin would specifically form protein adducts during synthesis, thus exposing their thiol groups, which are known to be especially vulnerable to reactive oxygen species.

Relationships between genetic polymorphisms and anticancer drug cytotoxicity vis-à-vis the NCI-60 panel.

INTRODUCTION: The National Cancer Institute (NCI)-60 panel consists of 60 human tumor cell lines initially established for screening thousands of molecules for antiproliferative activity. It has been powerful for deciphering the relationships between anticancer drug cytotoxicity and cell molecular characteristics. We tested its potential interest for establishing relationships between the polymorphism of genes involved in drug metabolism and transport or in DNA repair, and drug cytotoxicity extracted from NCI databases. METHODS: Using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) techniques, three frequent single nucleotide polymorphisms (SNPs) were analyzed: Lys751Gln in the Xeroderma pigmentosum complementation group D (XPD, ERCC2) gene, Asp1104His in the Xeroderma pigmentosum complementation group G (XPG, ERCC5) gene and Ile105Val in the glutathione S-transferase P1 (GSTP1) gene. RESULTS: The allelic frequencies of the variants were 33% for ERCC2, 23% for ERCC5 and 39% for GSTP1. The ERCC2 polymorphism appeared to be a strong determinant of the in vitro cytotoxicity of most anticancer agents, with lower half maximal inhibitory concentration (IC50) values in variant homozygous lines than in common homozygous or heterozygous cell lines. Unexpectedly, the cytotoxicity of taxanes appeared markedly dependent upon the ERCC2 genotype, with threefold lower mean IC50 values in variant homozygous cell lines. The ERCC5 genotype appeared to be important only for taxanes, with fourfold higher IC50 values in variant homozygous cell lines. The GSTP1 polymorphism was related to the cytotoxicity of several drug classes, especially topoisomerase inhibitors, antimetabolites and N7 alkylating agents. CONCLUSION: The NCI-60 panel is capable of providing clues and tracks for the establishment of clinically useful relationships between a given genotype and the cytotoxicity of an anticancer agent.

In vitro prevention of cyclosporin-induced cell contraction by mycophenolic acid.

Nephrotoxicity is a major side-effect of cyclosporin A (CsA), which induces a vasoconstrictive response in vascular smooth muscle and mesangial cells. Mycophenolic acid (MPA) is used in combination with low-dose CsA to reduce nephrotoxicity. We previously demonstrated that MPA affected mesangial cell contractile response to angiotensin II or KCl. Aims of the present study were to evaluate if MPA can prevent CsA-induced contraction of human mesangial and aortic smooth muscle cells (ASMC). Using a morphoquantitative approach, we evidenced that pretreatment with MPA (1 microM) prevented the reduction of cell area induced by CsA within 30 min in both cell types. We then compared the expression of three main cytoskeleton proteins: tubulin, alpha-smooth actin (SMA) and basic calponin, in ASMC and in mesangial cells treated with MPA and/or CsA. CsA alone did not significantly change the expression level of these proteins neither in mesangial cells nor in ASMC. MPA decreased the expression level of tubulin in both mesangial cells and ASMC. Surprisingly, MPA, which stimulated SMA and calponin expression in mesangial cells, exerted an inhibitory effect on both contractile protein expression in ASMC. In conclusion, our results evidenced opposite effects of MPA on calponin and SMA protein expression in ASMC and in mesangial cells, despite similar antiproliferative properties, suggesting that sarcomeric protein expression is controlled by different intracellular mechanisms in mesangial and smooth muscle cells. However, MPA interferes in both cell types with the constrictive properties CsA, which may partially explain the protective effects of MPA against CsA nephrotoxicity.

Predicting drug response and toxicity based on gene polymorphisms.

The sequencing of the human genome has allowed the identification of thousands of gene polymorphisms, most often single nucleotide polymorphims (SNP), which may play an important role in the expression level and activity of the corresponding proteins. When these polymorphisms occur at the level of drug metabolising enzymes or transporters, the disposition of the drug may be altered and, consequently, its efficacy may be compromised or its toxicity enhanced. Polymorphisms can also occur at the level of proteins directly involved in drug action, either when the protein is the target of the drug or when the protein is involved in the repair of drug-induced lesions. There again, these polymorphisms may lead to alterations in drug efficacy and/or toxicity. The identification of functional polymorphisms in patients undergoing chemotherapy may help the clinician prescribe the optimal drug combination or schedule and predict with more accuracy the response to these prescriptions. We have recorded in this review the polymorphisms that have been identified up till now in genes involved in anticancer drug activity. Some of them appear especially important in predicting drug toxicity and should be determined in routine before drug administration; this is the case of the most common variations of thiopurine methyltransferase for 6-mercaptopurine and of dihydropyrimidine dehydrogenase for fluorouracil. Other appear determinant for drug response, such as the common SNPs found in glutathione S-transferase P1 or xereoderma pigmentosum group D enzyme for the activity of oxaliplatin. However, confusion factors may exist between the role of gene polymorphisms in cancer risk or overall prognosis and their role in drug response.

Hsp70 and Hsp40 chaperones do not modulate retinal phenotype in SCA7 mice.

Nine neurodegenerative diseases, including spinocerebellar ataxia type 7 (SCA7), are caused by the expansion of polyglutamine stretches in the respective disease-causing proteins. A hallmark of these diseases is the aggregation of expanded polyglutamine-containing proteins in nuclear inclusions that also accumulate molecular chaperones and components of the ubiquitin-proteasome system. Manipulation of HSP70 and HSP40 chaperone levels has been shown to suppress aggregates in cellular models, prevent neuronal death in Drosophila, and improve to some extent neurological symptoms in mouse models. An important issue in mammals is the relative expression levels of toxic and putative rescuing proteins. Furthermore, overexpression of both HSP70 and its co-factor HSP40/HDJ2 has never been investigated in mice. We decided to address this question in a SCA7 transgenic mouse model that progressively develops retinopathy, similar to SCA7 patients. To co-express HSP70 and HDJ2 with the polyglutamine protein, in the same cell type, at comparable levels and with the same time course, we generated transgenic mice that express the heat shock proteins specifically in rod photoreceptors. While co-expression of HSP70 with its co-factor HDJ2 efficiently suppressed mutant ataxin-7 aggregation in transfected cells, they did not prevent either neuronal toxicity or aggregate formation in SCA7 mice. Furthermore, nuclear inclusions in SCA7 mice were composed of a cleaved mutant ataxin-7 fragment, whereas they contained the full-length protein in transfected cells. We propose that differences in the aggregation process might account for the different effects of chaperone overexpression in cellular and animal models of polyglutamine diseases.

Semicarbazide-sensitive amine oxidase in annulo-aortic ectasia disease: relation to elastic lamellae-associated proteins.

Lysyl oxidases (Lox), which are members of the amine oxidase family, are involved in the maturation of elastic lamellae and collagen fibers. Modifications of amine oxidases in idiopathic annulo-aortic ectasia disease (IAAED) have never been investigated. Our aim was to examine the expression of several proteins that might interfere with elastic fiber organization in control (n=10) and IAAED (n=18) aortic tissues obtained at surgery. Expression of amine oxidases and semicarbazide-sensitive amine oxidase (SSAO), and cellular phenotypic markers were examined by immunohistopathology and confocal microscopy. The expression of these proteins was assessed in relation to clinical and histomorphological features of the arterial wall. In control aorta, SSAO staining was expressed along elastic lamellae, whereas in aneurysmal areas of IAAED, SSAO was markedly decreased, in association with severe disorganization of elastic lamellae. Smooth muscle myosin heavy chain was also decreased in IAAED compared with controls, indicating smooth muscle cell dedifferentiation. Multiple regression analysis showed that elastic lamellar thickness (ELT) was correlated positively with the SSAO:elastin ratio and negatively with the Lox:elastin ratio, and that the clinical features of IAAED (aneurysm, thoracic aorta diameter, and aortic insufficiency) were positively correlated with ELT but not with SSAO. The relationship between SSAO expression and ELT suggests that this amine oxidase may be involved in elastic fiber organization. However, in advanced IAAED, the deficit in SSAO expression could be secondary to the decrease and fragmentation of elastic fibers and/or to vascular smooth muscle cell dedifferentiation.

Predicting drug response based on gene expression.

Predicting drug response is a challenging problem in oncology. In the 1975-1985 decade, important efforts were devoted to the generation of cellular assays able to predict, on an individual basis, the in vitro response of tumour cells to chemotherapeutic agents, but such methods could not be adopted in routine. Numerous mechanisms of resistance to anticancer agents have been identified in cultured cell lines selected for growth in the presence of infratoxic, increasing doses of anticancer agents. They mainly concern drug transport, drug activation or detoxification, target quantitative or qualitative alterations, DNA repair efficiency, and alterations in signalling and/or execution of cell death programmes. New molecular biology techniques have been developed in order to identify the genes involved in drug resistance; they mainly involve differential expression techniques, but functional approaches may also prove informative. The availability of techniques of gene expression profiling has allowed to establish correlations between gene expression and drug sensitivity of tumour cells or human cancers. This type of approach has been initiated on in vitro systems by the National Cancer Institute (NCI) in the USA and is pursued by a growing number of public and private laboratories around the world. In the clinical setting, a number of genes or proteins have been identified as potential predictive markers of drug activity and their use could be progressively implemented for drug selection in patients receiving chemotherapy, allowing thus more rational and individualised treatments.

[Recent advances in pharmacogenomics in oncology]. / Actualités en pharmacogénomique des cancers.

Progress in understanding the molecular mechanisms of oncogenesis, together with the sequencing of the human genome and the availability of huge databases, bring new tools for the discovery and the evaluation of new potential targets for cancer therapy and for the individualisation of cancer chemotherapy as a function of the molecular characteristics of tumours. Targeting the genetic alterations of cancer cells appears feasible and the first successes of this approach allow to remain optimistic about the renewal of our therapeutic armamentarium. In addition, seeking for correlations between gene expression profiles and chemosensitivity has been performed on the in vitro models of the National Cancer Institute and may allow crucial improvements in the identification of patients who world best take advantage of a specific chemotherapy. Clinical trials, first on a retrospective basis, then performed prospectively, are implemented to validate this approach.