VEGF over-expression in skeletal muscle induces angiogenesis by intussusception rather than sprouting

Therapeutic over-expression of vascular endothelial growth factor (VEGF) can be used to treat ischemic conditions. However, VEGF can induce either normal or aberrant angiogenesis depending on its dose in the microenvironment around each producing cell in vivo, which limits its clinical usefulness. The goal herein was to determine the cellular mechanisms by which physiologic and aberrant vessels are induced by over-expression of different VEGF doses in adult skeletal muscle. We took advantage of a well-characterized cell-based platform for controlled gene expression in skeletal muscle. Clonal populations of retrovirally transduced myoblasts were implanted in limb muscles of immunodeficient mice to homogeneously over-express two specific VEGF(164) levels, previously shown to induce physiologic and therapeutic or aberrant angiogenesis, respectively. Three independent and complementary methods (confocal microscopy, vascular casting and 3D-reconstruction of serial semi-thin sections) showed that, at both VEGF doses, angiogenesis took place without sprouting, but rather by intussusception, or vascular splitting. VEGF-induced endothelial proliferation without tip-cell formation caused an initial homogeneous enlargement of pre-existing microvessels, followed by the formation of intravascular transluminal pillars, hallmarks of intussusception. This was associated with increased flow and shear stress, which are potent triggers of intussusception. A similar process of enlargement without sprouting, followed by intussusception, was also induced by VEGF over-expression through a clinically relevant adenoviral gene therapy vector, without the use of transduced cells. Our findings indicate that VEGF over-expression, at doses that have been shown to induce functional benefit, induces vascular growth in skeletal muscle by intussusception rather than sprouting.

Early over-expression of GRP receptors in prostatic carcinogenesis

BACKGROUND The GRP receptor shows high over-expression in prostatic adenocarcinoma and high grade PIN, but low expression in normal prostate glands. This represents the molecular basis for GRP receptor imaging of prostate cancer with radioactive compounds. However, a focal, high density GRP receptor expression can be observed in hitherto uncharacterized prostate glands. METHODS GRP receptors were quantitatively measured with in vitro receptor autoradiography using ¹²⁵I-Tyr⁴ -bombesin in samples from 115 prostates. On successive tissue sections, ¹²⁵I-Tyr⁴ -bombesin autoradiography was compared with H&E staining and MIB-1 and 34βE12 immunohistochemistry. RESULTS On one hand, it was confirmed that GRP receptors were expressed in adenocarcinoma and high grade PIN in high density and high incidence (77% and 73%, respectively), but in normal prostate glands in low density and low frequency (18%). On the other hand, a novel and intriguing observation was the existence of focal non-invasive prostate glands with high GRP receptor density, characterized by low grade nuclear atypia and increased proliferation, compatible with lower grade PIN. There was a significant GRP receptor density gradient (P ≤ 0.005), increasing from normal prostate glands (mean relative optical density, ROD, of ¹²⁵I-Tyr⁴ -bombesin binding: 0.17) over atypical glands without increased MIB-1 labeling (0.28) and atypical glands with increased MIB-1 expression (0.44) to high grade PIN and adenocarcinoma (0.64 and 0.58, respectively). CONCLUSIONS GRP receptor over-expression may be a novel, specific marker of early prostatic neoplastic transformation, arising in low grade PIN, and progressively increasing during malignant progression. This should be considered when interpreting in vivo GRP receptor imaging in males.

The TRANSPLANTA collection of Arabidopsis lines: a resource for functional analysis of transcription factors based on their conditional over-expression

Transcription factors (TFs) are key regulators of gene expression in all organisms. In eukaryotes, TFs are often represented by functionally redundant members of large gene families. Overexpression might prove a means to unveil the biological functions of redundant TFs; however, constitutive overexpression of TFs frequently causes severe developmental defects, preventing their functional characterization. Conditional overexpression strategies help to overcome this problem. Here, we report on the TRANSPLANTA collection of Arabidopsis lines, each expressing one of 949 TFs under the control of a β–estradiol-inducible promoter. Thus far, 1636 independent homozygous lines, representing an average of 2.6 lines for every TF, have been produced for the inducible expression of 634 TFs. Along with a GUS-GFP reporter, randomly selected TRANSPLANTA lines were tested and confirmed for conditional transgene expression upon β–estradiol treatment. As a proof of concept for the exploitation of this resource, β–estradiol-induced proliferation of root hairs, dark-induced senescence, anthocyanin accumulation and dwarfism were observed in lines conditionally expressing full-length cDNAs encoding RHD6, WRKY22, MYB123/TT2 and MYB26, respectively, in agreement with previously reported phenotypes conferred by these TFs. Further screening performed with other TRANSPLANTA lines allowed the identification of TFs involved in different plant biological processes, illustrating that the collection is a powerful resource for the functional characterization of TFs. For instance, ANAC058 and a TINY/AP2 TF were identified as modulators of ABA-mediated germination potential, and RAP2.10/DEAR4 was identified as a regulator of cell death in the hypocotyl–root transition zone. Seeds of TRANSPLANTA lines have been deposited at the Nottingham Arabidopsis Stock Centre for further distribution.

Anterior axis duplication in Xenopus induced by the over-expression of the cadherin-binding protein plakoglobin.

Plakoglobin interacts with both classical and desmosomal cadherins. It is closely related to Drosophila aramadillo (arm) gene product; arm acts in the wingless (wg)-signaling pathway to establish segment polarity. In Xenopus, homologs of wg--i.e., wnts, can produce anterior axis duplications by inducing dorsal mesoderm. Studies in Drosophila suggest that wnt acts by increasing the level of cytoplasmic armadillo protein (arm). To test whether simply increasing the level of plakoglobin mimics the effects of exogenous wnts in Xenopus, we injected fertilized eggs with RNA encoding an epitope-tagged form of plakoglobin; this induced both early radial gastrulation and anterior axis duplication. Exogenous plakoglobin accumulates in the nuclei of embryonic cells. Plakoglobin binds to the tail domain of the desmosomal cadherin desmoglein 1. When RNA encoding the tail domain of desmoglein was coinjected with plakoglobin RNA, both the dorsalizing effect and nuclear accumulation of plakoglobin were suppressed. Mutational analysis indicates that the central arm repeat region of plakoglobin is sufficient to induce axis duplication and that this polypeptide accumulates in the nuclei of embryonic cells. These data show that increased plakoglobin levels can, by themselves, generate the intracellular signals involved in the specification of dorsal mesoderm.

Altered fungal sensitivity to a plant antimicrobial peptide through over-expression of yeast cDNAs

A yeast cDNA expression library was screened to identify genes and cellular processes that influence fungal sensitivity to a plant antimicrobial peptide. A plasmid-based, GAL1 promoter-driven yeast cDNA expression library was introduced into a yeast genotype susceptible to the antimicrobial peptide MiAMP1 purified from Macadamia integrifolia. Following a screen of 20,000 cDNAs, three yeast cDNAs were identified that reproducibly provided transformants with galactose-dependent resistance to MiAMP1. These cDNAs encoded a protein of unknown function, a component (VMA11) of the vacuolar H+-ATPase and a component (cytochrome c oxidase subunit VIa) of the mitochondrial electron transport chain, respectively. To identify genes that increased sensitivity to MiAMP1, the yeast cDNA expression library was introduced into a yeast mutant with increased resistance to MiAMP1. From 11,000 cDNAs screened, two cDNA clones corresponding to a ser/thr kinase and a ser/thr phosphatase reproducibly increased MiAMP1 susceptibility in the mutant in a galactose-dependent manner. Deletion mutants were available for three of the five genes identified but showed no change in their sensitivity to MiAMP1, indicating that these genes could not be detected by screening of yeast deletion mutant libraries. Yeast cDNA expression library screening therefore provides an alternative approach to gene deletion libraries to identify genes that can influence the sensitivity of fungi to plant antimicrobial peptides.

Over-expression of Eph and ephrin genes in advanced ovarian cancer: ephrin gene expression correlates with shortened survival

Background: Increased expression of Eph receptor tyrosine kinases and their ephrin ligands has been implicated in tumor progression in a number of malignancies. This report describes aberrant expression of these genes in ovarian cancer, the commonest cause of death amongst gynaecological malignancies. Methods: Eph and ephrin expression was determined using quantitative real time RT-PCR. Correlation of gene expression was measured using Spearman's rho statistic. Survival was analysed using log-rank analysis and ( was visualised by) Kaplan-Meier survival curves. Results: Greater than 10 fold over-expression of EphA1 and a more modest over-expression of EphA2 were observed in partially overlapping subsets of tumors. Over-expression of EphA1 strongly correlated ( r = 0.801; p < 0.01) with the high affinity ligand ephrin A1. A similar trend was observed between EphA2 and ephrin A1 ( r = 0.387; p = 0.06). A striking correlation of both ephrin A1 and ephrin A5 expression with poor survival ( r = - 0.470; p = 0.02 and r = - 0.562; p < 0.01) was observed. Intriguingly, there was no correlation between survival and other clinical parameters or Eph expression. Conclusion: These data imply that increased levels of ephrins A1 and A5 in the presence of high expression of Ephs A1 and A2 lead to a more aggressive tumor phenotype. The known functions of Eph/ephrin signalling in cell de-adhesion and movement may explain the observed correlation of ephrin expression with poor prognosis.

Over-Expression of Endothelin 3 Sensitizes Mice to Uv-Induced Melanoma Metastasis

Melanomagenesis is influenced by environmental and genetic factors. In normal cells, ultraviolet (UV) induced photoproducts are successfully repaired by the nucleotide excision repair (NER) pathway. Mice carrying mutations in the xeroderma pigmentosum (Xp) complementation group of genes (Xpa-Xpg) lack the NER pathway and are therefore highly sensitive to UV light; however, they do not develop melanoma after UV exposure. In humans, the Endothelin 3 signaling pathway has been linked to melanoma progression and its metastatic potential. Transgenic mice that over-express Edn3 under the control of the Keratin 5 promoter (K5-Edn3) and exhibit a hyperpigmentation phenotype, were crossed with Xp deficient mice. Because melanoma is highly metastatic and many primary malignancies spread via the lymphatic system, analyzing the lymph nodes may serve useful in assessing the possible spread of tumor cells to other tissues. This study aimed to determine whether the over-expression of Edn3 is sufficient to lead to melanoma metastasis to the lymph nodes. Mice were exposed to UV radiation and analyzed for the presence of skin lesions. Mice presenting skin lesions were sacrificed and the nearest lymph nodes were excised and examined for the presence of metastasis. Mice with melanoma skin lesions presented enlarged and hyperpigmented lymph nodes. Diagnosis of melanoma was established by immunostaining with melanocyte and melanoma cell markers, and while UV radiation caused the development of skin lesions in both K5-Edn3 transgenic and control mice, only those mice carrying the K5-Edn3 transgene were found to develop melanoma metastasis to the lymph nodes. These results indicate that over-expression of Edn3 is sufficient to lead to lymph node metastasis in mice exposed to at least one dose of UV radiation.

UV-induced melanoma mouse model dependent on endothelin 3 over-expression

Melanoma is one of the most aggressive types of cancer. It originates from the transformation of melanocytes present in the epidermal/dermal junction of the human skin. It is commonly accepted that melanomagenesis is influenced by the interaction of environmental factors, genetic factors, as well as tumor-host interactions. DNA photoproducts induced by UV radiation are, in normal cells, repaired by the nucleotide excision repair (NER) pathway. The prominent role of NER in cancer resistance is well exemplified by patients with Xeroderma Pigmentosum (XP). This disease results from mutations in the components of the NER pathway, such as XPA and XPC proteins. In humans, NER pathway disruption leads to the development of skin cancers, including melanoma. Similar to humans afflicted with XP, Xpa and Xpc deficient mice show high sensibility to UV light, leading to skin cancer development, except melanoma. The Endothelin 3 (Edn3) signaling pathway is essential for proliferation, survival and migration of melanocyte precursor cells. Excessive production of Edn3 leads to the accumulation of large numbers of melanocytes in the mouse skin, where they are not normally found. In humans, Edn3 signaling pathway has also been implicated in melanoma progression and its metastatic potential. The goal of this study was the development of the first UV-induced melanoma mouse model dependent on the over-expression of Edn3 in the skin. The UV-induced melanoma mouse model reported here is distinguishable from all previous published models by two features: melanocytes are not transformed a priori and melanomagenesis arises only upon neonatal UV exposure. In this model, melanomagenesis depends on the presence of Edn3 in the skin. Disruption of the NER pathway due to the lack of Xpa or Xpc proteins was not essential for melanomagenesis; however, it enhanced melanoma penetrance and decreased melanoma latency after one single neonatal erythemal UV dose. Exposure to a second dose of UV at six weeks of age did not change time of appearance or penetrance of melanomas in this mouse model. Thus, a combination of neonatal UV exposure with excessive Edn3 in the tumor microenvironment is sufficient for melanomagenesis in mice; furthermore, NER deficiency exacerbates this process.^

UV-Induced Melanoma Mouse Model Dependent on Endothelin 3 Over-Expression

Melanoma is one of the most aggressive types of cancer. It originates from the transformation of melanocytes present in the epidermal/dermal junction of the human skin. It is commonly accepted that melanomagenesis is influenced by the interaction of environmental factors, genetic factors, as well as tumor-host interactions. DNA photoproducts induced by UV radiation are, in normal cells, repaired by the nucleotide excision repair (NER) pathway. The prominent role of NER in cancer resistance is well exemplified by patients with Xeroderma Pigmentosum (XP). This disease results from mutations in the components of the NER pathway, such as XPA and XPC proteins. In humans, NER pathway disruption leads to the development of skin cancers, including melanoma. Similar to humans afflicted with XP, Xpa and Xpc deficient mice show high sensibility to UV light, leading to skin cancer development, except melanoma. The Endothelin 3 (Edn3) signaling pathway is essential for proliferation, survival and migration of melanocyte precursor cells. Excessive production of Edn3 leads to the accumulation of large numbers of melanocytes in the mouse skin, where they are not normally found. In humans, Edn3 signaling pathway has also been implicated in melanoma progression and its metastatic potential. The goal of this study was the development of the first UV-induced melanoma mouse model dependent on the over-expression of Edn3 in the skin. The UV-induced melanoma mouse model reported here is distinguishable from all previous published models by two features: melanocytes are not transformed a priori and melanomagenesis arises only upon neonatal UV exposure. In this model, melanomagenesis depends on the presence of Edn3 in the skin. Disruption of the NER pathway due to the lack of Xpa or Xpc proteins was not essential for melanomagenesis; however, it enhanced melanoma penetrance and decreased melanoma latency after one single neonatal erythemal UV dose. Exposure to a second dose of UV at six weeks of age did not change time of appearance or penetrance of melanomas in this mouse model. Thus, a combination of neonatal UV exposure with excessive Edn3 in the tumor microenvironment is sufficient for melanomagenesis in mice; furthermore, NER deficiency exacerbates this process.

Epigenetic and oncogenic regulation of SLC16A7 (MCT2) results in protein over-expression, impacting on signalling and cellular phenotypes in prostate cancer

Monocarboxylate Transporter 2 (MCT2) is a major pyruvate transporter encoded by the SLC16A7 gene. Recent studies pointed to a consistent overexpression of MCT2 in prostate cancer (PCa) suggesting MCT2 as a putative biomarker and molecular target. Despite the importance of this observation the mechanisms involved in MCT2 regulation are unknown. Through an integrative analysis we have discovered that selective demethylation of an internal SLC16A7/MCT2 promoter is a recurrent event in independent PCa cohorts. This demethylation is associated with expression of isoforms differing only in 5'-UTR translational control motifs, providing one contributing mechanism for MCT2 protein overexpression in PCa. Genes co-expressed with SLC16A7/MCT2 also clustered in oncogenic-related pathways and effectors of these signalling pathways were found to bind at the SLC16A7/MCT2 gene locus. Finally, MCT2 knock-down attenuated the growth of PCa cells. The present study unveils an unexpected epigenetic regulation of SLC16A7/MCT2 isoforms and identifies a link between SLC16A7/MCT2, Androgen Receptor (AR), ETS-related gene (ERG) and other oncogenic pathways in PCa. These results underscore the importance of combining data from epigenetic, transcriptomic and protein level changes to allow more comprehensive insights into the mechanisms underlying protein expression, that in our case provide additional weight to MCT2 as a candidate biomarker and molecular target in PCa.

Copy number variation modifies expression profiles over developmental time

Abstract : A preliminary understanding of the phenotypic effect of copy number variation (CNV) of DNA segments is emerging. These rearrangements were shown to influence, in a somewhat dose-dependent manner, the expression of genes mapping within them. They were also shown to modify the expression of genes located on their Hanks, sometimes at great distance. Here, we demonstrate by monitoring these effects at multiple life stages, that these controls over expression are effective throughout mouse development. Similarly, we observe that the more specific spatial expression patterns of CNV genes are maintained through life. However, 'we find that some brain- expressed genes mapping within CNVS appear to be under compensatory loops only at specific time-points, indicating that the effect of CNVS on these genes is modulated during development. Notably, we also observe that CNV genes are significantly enriched within transcripts that show variable time-course expression between strains. Thus, modifying the copy number of a gene may potentially alter not only its expression level, but its timing of expression as well. Résume : Nous commençons à comprendre les effets phénotypiques liés aux séquences d'ADN qui changent de nombre de copies d'un individu a l'autre. Des travaux précédents ont montré que ces variante de nombre de copies (CNVS) avaient une influence sur l'expression non seulement des gènes se trouvant dans le réarrangement, mais aussi sur ceux se trouvant à une certaine distance. Le présent travail étudie ces effets à différents stades du développement de la souris allant d'un embryon de deux semaines à la souris adulte. Nous avons observé que certains gènes exprimés dans le cerveau semblent soumis à un contrôle plus strict a certaines étapes du développement suggèrent que l'effet des CNVs est modulé différemment au cours de la vie. Notre travail sur trois souches différentes de souris a permis de montrer que les gènes ayant un profil d'expression différent dans le temps entre souches sont enrichis en gènes se trouvant dans des CNVs. Ceci nous amène à penser que les CNVs ont, non seulement une influence sur le niveau d'expression des gènes, mais aussi sur les moments durant lesquels ils seront exprimés. Résumé pour un large public : De nombreuses maladies sont dues soit a un gain (on parle alors de duplication) soit à une perte de matériel génétique (il s'agit dune délétion). Bien que les recherches visant à identifier les mécanismes moléculaires liés à ces réarrangements de notre génome progressent continuellement, la plupart des causes des maladies génétiques restent à élucider. Certaines parties de notre génome sont présentes en un nombre de copies qui diffère d'un individu à l'autre sans pour autant provoquer une ou des maladies. Ces segments d'ADN qui varient en nombre sont appelés Copy Number Variant (CNVs). Ils couvrent environ 12% de notre matériel génétique. Des études menées sur différents modèles animaux ont montré que les CNVs avaient une influence aussi bien sur les gènes qui sont a l'intérieur des CNVs que sur ceux qui sont dans leur voisinage. Ce travail étudie l'effet des CNVs à travers différents stades du développement de la souris. Nous avons démontré que les segments d'ADN qui varient en nombre de copies ont des effets variables selon le stade auxquels ils sont mesurés. Ainsi, les CNVs ont non seulement un impact sur l'expression des gènes présents dans ces régions et dans leur voisinage, mais influencent également leurs profils d'expression au cours du temps.

Sequential analysis of global gene expression profiles in immature and in vitro matured bovine oocytes: potential molecular markers of oocyte maturation

Background: Without intensive selection, the majority of bovine oocytes submitted to in vitro embryo production (IVP) fail to develop to the blastocyst stage. This is attributed partly to their maturation status and competences. Using the Affymetrix GeneChip Bovine Genome Array, global mRNA expression analysis of immature (GV) and in vitro matured (IVM) bovine oocytes was carried out to characterize the transcriptome of bovine oocytes and then use a variety of approaches to determine whether the observed transcriptional changes during IVM was real or an artifact of the techniques used during analysis. Results: 8489 transcripts were detected across the two oocyte groups, of which similar to 25.0% (2117 transcripts) were differentially expressed (p < 0.001); corresponding to 589 over-expressed and 1528 under-expressed transcripts in the IVM oocytes compared to their immature counterparts. Over expression of transcripts by IVM oocytes is particularly interesting, therefore, a variety of approaches were employed to determine whether the observed transcriptional changes during IVM were real or an artifact of the techniques used during analysis, including the analysis of transcript abundance in oocytes in vitro matured in the presence of a-amanitin. Subsets of the differentially expressed genes were also validated by quantitative real-time PCR (qPCR) and the gene expression data was classified according to gene ontology and pathway enrichment. Numerous cell cycle linked (CDC2, CDK5, CDK8, HSPA2, MAPK14, TXNL4B), molecular transport (STX5, STX17, SEC22A, SEC22B), and differentiation (NACA) related genes were found to be among the several over-expressed transcripts in GV oocytes compared to the matured counterparts, while ANXA1, PLAU, STC1and LUM were among the over-expressed genes after oocyte maturation. Conclusion: Using sequential experiments, we have shown and confirmed transcriptional changes during oocyte maturation. This dataset provides a unique reference resource for studies concerned with the molecular mechanisms controlling oocyte meiotic maturation in cattle, addresses the existing conflicting issue of transcription during meiotic maturation and contributes to the global goal of improving assisted reproductive technology.

The Role of Prostate Specific Membrane Antigen and Pepsinogen C Tissue Expression as an Adjunctive Method to Prostate Cancer Diagnosis

Purpose: The diagnosis of prostate cancer in men with persistently increased prostate specific antigen after a negative prostate biopsy has become a great challenge for urologists and pathologists. We analyzed the diagnostic value of 6 genes in the tissue of patients with prostate cancer. Materials and Methods: The study was comprised of 50 patients with localized disease who underwent radical prostatectomy. Gene selection was based on a previous microarray analysis. Among 4,147 genes with different expressions between 2 pools of patients 6 genes (PSMA, TMEFF2, GREB1, TH1L, IgH3 and PGC) were selected. These genes were tested for diagnostic value using the quantitative reverse transcription polymerase chain reaction method. Initially malignant tissue samples from 33 patients were analyzed and in the second part of the study we analyzed benign tissue samples from the other 17 patients with prostate cancer. The control group was comprised of tissue samples of patients with benign prostatic hyperplasia. Results: Analysis of malignant prostatic tissue demonstrated that prostate specific membrane antigen was over expressed (mean 9 times) and pepsinogen C was under expressed (mean 1.3 X 10(-4) times) in all cases compared to benign prostatic hyperplasia. The other 4 tested genes showed a variable expression pattern not allowing for differentiation between benign and malignant cases. When we tested these results in the benign prostate tissues from patients with cancer, pepsinogen C maintained the expression pattern. In terms of prostate specific membrane antigen, despite over expression in most cases (mean 12 times), 2 cases (12%) presented with under expression. Conclusions: Pepsinogen C tissue expression may constitute a powerful adjunctive method to prostate biopsy in the diagnosis of prostate cancer cases.

Prognostic value of NDRG1 and SPARC protein expression in breast cancer patients

An increasing number of studies have shown altered expression of secreted protein acidic and rich in cysteine (SPARC) and N-myc down-regulated gene (NDRG1) in several malignancies, including breast carcinoma; however, the role of these potential biomarkers in tumor development and progression is controversial. In this study, NDRG1 and SPARC protein expression was evaluated by immunohistochemistry on tissue microarrays containing breast tumor specimens from patients with 10 years of follow-up. NDRG1 and SPARC protein expression was determined in 596 patients along with other prognostic markers, such as ER, PR, and HER2. The status of NDRG1 and SPARC protein expression was correlated with prognostic variables and patient clinical outcome. Immunostaining revealed that 272 of the 596 cases (45.6%) were positive for NDRG1 and 431 (72.3%) were positive for SPARC. Statistically significant differences were found between the presence of SPARC and NDRG1 protein expression and standard clinicopathological variables. Kaplan-Meier analysis showed that NDRG1 positivity was directly associated with shorter disease-free survival (DFS, P < 0.001) and overall survival (OS, P < 0.001). In contrast, patients expressing low levels of SPARC protein had worse DFS (P = 0.001) and OS (P = 0.001) compared to those expressing high levels. Combined analysis of the two markers indicated that DFS (P < 0.001) and OS rates (P < 0.001) were lowest for patients with NDRG1-positive and SPARC-negative tumors. Furthermore, NDRG1 over-expression and SPARC down-regulation correlated with poor prognosis in patients with luminal A or triple-negative subtype breast cancer. On multivariate analysis using a Cox proportional hazards model, NDRG1 and SPARC protein expression were independent prognostic factors for both DFS and OS of breast cancer patients. These data indicate that NDRG1 over-expression and SPARC down-regulation could play important roles in breast cancer progression and serve as useful biomarkers to better define breast cancer prognosis.

Differential expression of CDC25 phosphatases splice variants in human breast cancer cells

Background: CDC25 phosphatases control cell cycle progression by activating cyclin dependent kinases. The three CDC25 isoforms encoding genes are submitted to alternative splicing events which generate at least two variants for CDC25A and five for both CDC25B and CDC25C. An over-expression of CDC25 was reported in several types of cancer, including breast cancer, and is often associated with a poor prognosis. Nevertheless, most of the previous studies did not address the expression of CDC25 splice variants. Here, we evaluated CDC25 spliced transcripts expression in anti-cancerous drug-sensitive and resistant breast cancer cell lines in order to identify potential breast cancer biomarkers. Methods: CDC25 splice variants mRNA levels were evaluated by semi-quantitative RT-PCR and by an original real-time RT-PCR assay. Results: CDC25 spliced transcripts are differentially expres-sed in the breast cancer cell lines studied. An up-regulation of CDC25A2 variant and an increase of the CDC25C5/C1 ratio are associated to the multidrug-resistance in VCREMS and DOXOR breast cancer cells, compared to their sensitive counterpart cell line MCF-7. Additionally, CDC25B2 tran-script is exclusively over-expressed in VCREMS resistant cells and could therefore be involved in the development of certain type of drug resistance. Conclusions: CDC25 splice variants could represent interesting potential breast cancer prognostic biomarkers.