A low-frequency haplotype spanning SLX4/FANCP constitutes a new risk locus for early-onset breast cancer (<60 years) and is associated with reduced DNA repair capacity.

Only a fraction of breast cancer (BC) cases can be yet explained by mutations in genes or genomic variants discovered in linkage, genome-wide association and sequencing studies. The known genes entailing medium or high risk for BC are strongly enriched for a function in DNA double strand repair. Thus, aiming at identifying low frequency variants conferring an intermediate risk, we here investigated 17 variants (MAF: 0.01-0.1) in 10 candidate genes involved in DNA repair or cell cycle control. In an exploration cohort of 437 cases and 1189 controls, we show the variant rs3810813 in the SLX4/FANCP gene to be significantly associated with both BC (≤60 years; OR = 2.6(1.6-3.9), p = 1.6E-05) and decreased DNA repair capacity (≤60 years; beta = 37.8(17.9-57.8), p = 5.3E-4). BC association was confirmed in a verification cohort (N = 2441). Both associations were absent from cases diagnosed >60 years and stronger the earlier the diagnosis. By imputation we show that rs3810813 tags a haplotype with 5 additional variants with the same allele frequency (R2 > 0.9), and a pattern of association very similar for both phenotypes (cases <60 years, p < 0.001, the Bonferroni threshold derived from unlinked variants in the region). In young cases (≤60 years) carrying the risk haplotype, micronucleus test results are predictive for BC (AUC > 0.9). Our findings propose a risk variant with high penetrance on the haplotype spanning SLX4/FANCP to be functionally associated to BC predisposition via decreased repair capacity and suggest this variant is carried by a fraction of these haplotypes that is enriched in early onset BC cases.

VEGF but not PlGF disturbs the barrier of retinal endothelial cells.

Elevated permeability of retinal endothelial cells (REC), as observed in diabetic retinopathy (DR), is induced by extended exposure to ≥25 ng/ml vascular endothelial growth factor A165 (VEGF165) for up to 3 d and this effect is more pronounced when equimolar amounts of basic fibroblast growth factor (bFGF) and insulin-like growth factor (IGF-1) are present. Down-regulation of the tight-junction protein claudin-1 and its loss from the plasma membrane is associated with induced higher permeability, whereas other tight-junction proteins (e.g. claudin-3, claudin-5, ZO-1) show only subtle changes in our experimental setting. Using immortalized bovine REC (iBREC) as a well-established model, we investigated effects of other members of the VEGF family, i.e. VEGF121, placental growth factor (PlGF-1 and PlGF-2) and viral VEGF-E which activate different sets of VEGF receptors, on barrier function after extended treatment: iBREC were incubated with 1-100 ng/ml of the growth factors for up to 2 days before barrier function was assessed by measuring transendothelial resistance (TER). Presence of TJ-proteins was determined by western blot analyses and immunofluorescence staining. Similar experiments were performed to evaluate whether the primary actions of PlGF-1, PlGF-2 or VEGF121 are modulated by bFGF or IGF-1 when all growth factors (each at 25 ng/ml, but 10 ng/ml IGF-1) act simultaneously at equimolar concentrations. We also studied the potential normalization of the barrier disturbed with combinations of growth factors by addition of the VEGF-specific Fab fragment ranibizumab or the recombinant protein aflibercept which binds VEGF and PlGF. Whereas 1 ng/ml VEGF-E were sufficient to impair the iBREC barrier, a higher concentration of 100 ng/ml VEGF121 was needed to reduce TER and expression of claudin-1 over 2 days. By PlGF-1 or PlGF-2, the barrier was not affected even at the highest concentration tested (100 ng/ml) and these factors also did not modulate the effect of VEGF165. The weak barrier derangement caused by VEGF121 was slightly enhanced by bFGF and IGF-1. After induction of the barrier breakdown with various combinations of all growth factors included in the study, normal TER and claudin-1 expression was re-established by ranibizumab. Both VEGF inhibitors ranibizumab and aflibercept similarly reinstated lost claudin-1, even when applied at a small fraction of the clinically relevant concentrations. These results show that VEGF-A, but not PlGF impairs the barrier function of iBREC and that the longer isoform VEGF165 is more potent than VEGF121. To induce barrier dysfunction in iBREC, activation of VEGF receptor 2 - probably in concert with neuropilin-1 - seems to be sufficient because VEGF-E and VEGF165, but not PlGF-1/-2 reduced TER or claudin-1 expression.

Ranibizumab efficiently blocks migration but not proliferation induced by growth factor combinations including VEGF in retinal endothelial cells.

BACKGROUND: Proliferation and migration of retinal endothelial cells (REC) are associated with the development of proliferative diabetic retinopathy. REC proliferation is stimulated by isoforms of vascular endothelial growth factor-A (i.e., VEGF121 and VEGF165), basic fibroblast growth factor (bFGF), and insulin-like growth factor (IGF-1) of which VEGF165 also enhances migration of REC. Effects induced by VEGF-A can be blocked with ranibizumab, a VEGF-binding Fab fragment used in therapy of diabetic macular edema. In this study, we investigated potential angiogenic effects of placental growth factors (PlGF-1, PlGF-2) as other members of the VEGF family and whether the primary action of VEGF165 is modulated in the presence of bFGF, IGF-1 and PlGF-1/-2. We also studied how effects of growth factor combinations can be attenuated with ranibizumab. METHODS: Effects of single growth factors or their combinations on proliferation and migration of immortalized bovine retinal endothelial cells (iBREC) were studied with or without ranibizumab or the inhibitor of VEGF receptors KRN951. RESULTS: Proliferation of iBREC was significantly stimulated by 1-100 ng/ml PlGF-1 or PlGF-2, but additive effects were not observed with various combinations of the tested growth factors. Ranibizumab neutralized VEGF's effect on proliferation but was not effective when the other growth factors were used in combination with VEGF. bFGF and IGF-1 but not PlGF-1 or PlGF-2 stimulated iBREC migration as single agents, and they further enhanced VEGF-induced migration. The effects of such growth factor combinations including VEGF on migration were efficiently blocked by targeting only VEGF with ranibizumab. Migration induced by VEGF plus bFGF and IGF-1 was also almost completely inhibited by KRN951 interfering with VEGF receptor signalling. CONCLUSIONS: Migration but not proliferation of iBREC induced by combinations of bFGF, IGF-1, PlGF-1 or PlGF-2 together with VEGF is efficiently suppressed by ranibizumab. VEGF-mediated signalling through VEGFR2 seems to control REC migration dominantly in the presence of other growth factors.

Identification of alternative transcripts of rat CD9 expressed by tumorigenic neural cell lines and in normal tissues.

CD9 is the best-studied member of the tetraspanin family of transmembrane proteins. It is involved in various fundamental cellular processes and its altered expression is a characteristic of malignant cells of different origins. Despite numerous investigations confirming its fundamental role, the heterogeneity of CD9 or other tetraspanin proteins was considered only to be caused by posttranslational modification, rather than alternative splicing. Here we describe the first identification of CD9 transcript variants expressed by cell lines derived from fetal rat brain cells. Variant mRNA-B lacks a potential translation initiation codon in the alternative exon 1 and seems to be characteristic of the tumorigenic BT cell lines. In contrast, variant mRNA-C can be translated from a functional initiation codon located in its extended exon 2, and substantial amounts of this form detected in various tissues suggest a contribution to CD9 functions. From the alternative sequence of variant C, a different membrane topology (5 transmembrane domains) and a deviating spectrum of functions can be expected.

Association of death receptor 4 variant (683A > C) with ovarian cancer risk in BRCA1 mutation carriers.

Dysregulation of apoptosis plays an important role in carcinogenesis. Therefore, apoptosis-associated genes like the death receptor 4 (DR4, TRAIL-R1) are interesting candidates for modifying the penetrance of breast and ovarian cancer in carriers of BRCA1 and BRCA2 mutations. The DR-4 haplotype 626C-683C [626C > G, Thr209Arg (rs4871857) and 683A > C, Glu228Ala (rs17088993)] has recently been linked to an increased risk of breast cancer. To evaluate whether DR4 626C > G or DR4 683A > C modifies the risk of breast or ovarian cancer in carriers of BRCA1 and BRCA2 mutations, we undertook a national multicenter study including data of 840 carriers of breast cancer gene (BRCA) mutations. DNA samples were collected from 12 German research centers between 1996 and 2005 and were genotyped by the Taqman allelic discrimination assay. The association between genotypes and incidence of breast or ovarian cancer data was evaluated using a Cox proportional hazards regression model. We found evidence for a significant association of DR4 683A > C with a higher risk for ovarian cancer in carriers of BRCA1 mutations [n = 557, hazard ratio 1.78 (1.24-2.55), p = 0.009]. Our results thus indicate that the DR4 683A > C variant modifies the risk of ovarian cancer in carriers of BRCA1 mutations.

Germline mutations in the PALB2 gene are population specific and occur with low frequencies in familial breast cancer.

The Partner and Localizer of BRCA2 (PALB2) protein has been linked to Fanconi anemia and breast cancer predisposition. Here we present data of a comprehensive mutation screening of the PALB2 gene in 818 familial cases of breast cancer from Germany. By analyzing the entire coding region of PALB2, we found seven truncating mutations (six of them novel) in families tested negative for BRCA1/2-mutations. In addition, two novel potentially disease causing missense mutations were found. Remarkably, only one mutation reported previously in other populations, was also identified in the German population. No PALB2 mutation carriers were identified in 450 unaffected controls. Thus, our observations indicate a low prevalence of deleterious PALB2 mutations and a specific mutation profile within the German population. As PALB2-deficient tumors were shown to be sensitive to Poly(ADP-ribose) Polymerase (PARP) inhibitors, our study has implications for newly developed, favorable treatment options in familial breast cancer.

Common breast cancer-predisposition alleles are associated with breast cancer risk in BRCA1 and BRCA2 mutation carriers.

Germline mutations in BRCA1 and BRCA2 confer high risks of breast cancer. However, evidence suggests that these risks are modified by other genetic or environmental factors that cluster in families. A recent genome-wide association study has shown that common alleles at single nucleotide polymorphisms (SNPs) in FGFR2 (rs2981582), TNRC9 (rs3803662), and MAP3K1 (rs889312) are associated with increased breast cancer risks in the general population. To investigate whether these loci are also associated with breast cancer risk in BRCA1 and BRCA2 mutation carriers, we genotyped these SNPs in a sample of 10,358 mutation carriers from 23 studies. The minor alleles of SNP rs2981582 and rs889312 were each associated with increased breast cancer risk in BRCA2 mutation carriers (per-allele hazard ratio [HR] = 1.32, 95% CI: 1.20-1.45, p(trend) = 1.7 x 10(-8) and HR = 1.12, 95% CI: 1.02-1.24, p(trend) = 0.02) but not in BRCA1 carriers. rs3803662 was associated with increased breast cancer risk in both BRCA1 and BRCA2 mutation carriers (per-allele HR = 1.13, 95% CI: 1.06-1.20, p(trend) = 5 x 10(-5) in BRCA1 and BRCA2 combined). These loci appear to interact multiplicatively on breast cancer risk in BRCA2 mutation carriers. The differences in the effects of the FGFR2 and MAP3K1 SNPs between BRCA1 and BRCA2 carriers point to differences in the biology of BRCA1 and BRCA2 breast cancer tumors and confirm the distinct nature of breast cancer in BRCA1 mutation carriers.

pH-dependent vs. constant release of mesalazine in the treatment of ulcerative colitis: Do drug delivery concepts determine therapeutic efficacy? (Review).

Inflammatory bowel diseases (IBD) have developed to become a major global health problem. Ulcerative colitis (UC) is one of two main types of IBD, and >90% of patients suffering from mild or moderate forms of UC are treated with mesalazine, a well-tolerated and cost-effective drug. To allow oral administration, the drug has to be protected from resorption before it can reach the affected sites in the colon. The drug is therefore released from most currently used medications either constantly slow (time-dependent) or triggered by an increased pH during gastrointestinal transition. Both variants are widely used in clinical practice and it is surprising that they have not yet been compared directly in a large clinical study. In this overview, the evidence that may suggest preferential use of one type of mesalazine formulation over the other in general or for defined subgroups of patients is summarized and evaluated. Data from in vitro modelling of drug release and measurements of drug concentrations in colonic mucosa suggest that in many cases, constant release and pH-dependent formulations are of similar therapeutic efficiency; however, pH-triggered release may be superior in patients with proctitis-type UC or sites of inflammation in the proximal colon. Additionally, patients with a long gastric residence time, slow small intestinal transition, disease-related diarrhea or sensitivity to systemic adverse effects may benefit more from pH-dependent release formulations. In general, medications based on both concepts show similar efficacies, but the pH-dependent release formulations seem to be more robust in the treatment of a not further classified group of patients with UC. Future comparative clinical studies are required to clearly define the subgroups of patients that should be treated preferably with constant or pH-dependent release formulations of mesalazine.

Evidence for SMAD3 as a modifier of breast cancer risk in BRCA2 mutation carriers.

INTRODUCTION: Current attempts to identify genetic modifiers of BRCA1 and BRCA2 associated risk have focused on a candidate gene approach, based on knowledge of gene functions, or the development of large genome-wide association studies. In this study, we evaluated 24 SNPs tagged to 14 candidate genes derived through a novel approach that analysed gene expression differences to prioritise candidate modifier genes for association studies. METHODS: We successfully genotyped 24 SNPs in a cohort of up to 4,724 BRCA1 and 2,693 BRCA2 female mutation carriers from 15 study groups and assessed whether these variants were associated with risk of breast cancer in BRCA1 and BRCA2 mutation carriers. RESULTS: SNPs in five of the 14 candidate genes showed evidence of association with breast cancer risk for BRCA1 or BRCA2 carriers (P < 0.05). Notably, the minor alleles of two SNPs (rs7166081 and rs3825977) in high linkage disequilibrium (r² = 0.77), located at the SMAD3 locus (15q22), were each associated with increased breast cancer risk for BRCA2 mutation carriers (relative risk = 1.25, 95% confidence interval = 1.07 to 1.45, P(trend) = 0.004; and relative risk = 1.20, 95% confidence interval = 1.03 to 1.40, P(trend) = 0.018). CONCLUSIONS: This study provides evidence that the SMAD3 gene, which encodes a key regulatory protein in the transforming growth factor beta signalling pathway and is known to interact directly with BRCA2, may contribute to increased risk of breast cancer in BRCA2 mutation carriers. This finding suggests that genes with expression associated with BRCA1 and BRCA2 mutation status are enriched for the presence of common genetic modifiers of breast cancer risk in these populations.

Low-risk variants FGFR2, TNRC9 and LSP1 in German familial breast cancer patients.

To validate common low-risk variants predisposing for breast cancer (BC) in a large set of BRCA1/2 negative familial or genetically enriched cases from Germany, we genotyped 1,415 cases and 1,830 healthy women by MALDI-TOF in 105 candidate SNPs. Significantly higher ORs than previously reported for heterozygous unselected cases were found for the minor allele in FGFR2 (OR = 1.43, 95% CI 1.30-1.59, p-value = 1.24 x 10(-12)) and for TNRC9 (OR = 1.33, 95% CI 1.19-1.46, p-value = 1.54 x 10(-7)). Most intriguing, however, were the ORs for homozygous carriers from high-risk families for FGFR2 (OR = 2.05, 95% CI 1.68-2.51, LSP1 (OR = 0.49, 95% CI 0.28-0.86) and TNRC9 (OR = 1.62, 95% CI 1.27-2.07). Moreover, the additional validation of 99 CGEMS-SNPs identified putative novel susceptibility alleles within the LSP1 gene (OR = 0.73, 95% CI 0.61-0.87, p-value = 5.23 x 10(-4)). Finally, we provide evidence for the first time that a low-risk variant located at 6q22.33 (rs6569479) is associated with estrogen receptor negative BC in familial cases (OR = 1.33, 95% CI 1.06-1.66; p-value = 0.012). Our data confirm the impact of the previously identified susceptibility loci and provide preliminary evidence for novel susceptibility loci in familial BC cases and correlate them to specific histopathological subtypes defined by estrogen receptor status.

RAD51 135G-->C modifies breast cancer risk among BRCA2 mutation carriers: results from a combined analysis of 19 studies.

RAD51 is an important component of double-stranded DNA-repair mechanisms that interacts with both BRCA1 and BRCA2. A single-nucleotide polymorphism (SNP) in the 5' untranslated region (UTR) of RAD51, 135G-->C, has been suggested as a possible modifier of breast cancer risk in BRCA1 and BRCA2 mutation carriers. We pooled genotype data for 8,512 female mutation carriers from 19 studies for the RAD51 135G-->C SNP. We found evidence of an increased breast cancer risk in CC homozygotes (hazard ratio [HR] 1.92 [95% confidence interval {CI} 1.25-2.94) but not in heterozygotes (HR 0.95 [95% CI 0.83-1.07]; P=.002, by heterogeneity test with 2 degrees of freedom [df]). When BRCA1 and BRCA2 mutation carriers were analyzed separately, the increased risk was statistically significant only among BRCA2 mutation carriers, in whom we observed HRs of 1.17 (95% CI 0.91-1.51) among heterozygotes and 3.18 (95% CI 1.39-7.27) among rare homozygotes (P=.0007, by heterogeneity test with 2 df). In addition, we determined that the 135G-->C variant affects RAD51 splicing within the 5' UTR. Thus, 135G-->C may modify the risk of breast cancer in BRCA2 mutation carriers by altering the expression of RAD51. RAD51 is the first gene to be reliably identified as a modifier of risk among BRCA1/2 mutation carriers.

Multiplexed immunoassays for the analysis of breast cancer biopsies.

Within the last decade, protein microarray technology has been successfully used for the simultaneous quantification of target proteins from minimal amounts of samples in basic and applied proteome research. The robustness and appropriate sensitivity of these miniaturized assays have been demonstrated and thus the transfer to routine and high-throughput applications is now possible. In this study, multiplexed bead-based sandwich immunoassays were used to determine the concentrations of 54 protein analytes, including HER 2 and the estrogen receptor, from ultrasound-guided large-core needle biopsies (LCNBs) from breast cancer patients. Expression levels for HER 2, estrogen receptors and progesterone receptors were also assessed by immunohistochemical routine staining, performed in the clinic on corresponding biopsy samples. The high concordance of the data sets generated with the bead-based protein arrays and by conventional immunohistochemical assessment of HER 2 and the estrogen receptor expressed by breast cancer cells present in the biopsies was demonstrated.

Sitagliptin and the Blood-Retina Barrier: Effects on Retinal Endothelial Cells Manifested Only after Prolonged Exposure.

Inhibitors of dipeptidyl peptidase-4 (DPP-4) are widely used to treat diabetes mellitus, but data concerning their effects on the barrier stability of retinal endothelial cells (REC) in vivo and in vitro are inconsistent. Therefore, we studied whether the barrier properties of immortalized endothelial cells of the bovine retina (iBREC) were affected by the inhibitors of DPP-4 sitagliptin (10-1000 nM) and diprotin A (1-25 µM). Their effects were also investigated in the presence of VEGF-A165 because diabetic patients often develop macular edema caused by VEGF-A-induced permeability of REC. To detect even transient or subtle changes of paracellular and transcellular flow as well as adhesion of the cells to the extracellular matrix, we continuously monitored the cell index (CI) of confluent iBREC grown on gold electrodes. Initially, the CI remained stable but started to decline significantly and persistently at 40 h or 55 h after addition of sitagliptin or diprotin A, respectively. Both inhibitors did not modulate, prevent, or revert the persistent VEGF-A165-induced reduction of the CI. Interestingly, sitagliptin and diprotin A increased the expression of the tight-junction protein claudin-1 which is an important component of a functional barrier formed by iBREC. In contrast, expressions of CD29-a subunit of the fibronectin receptor-or of the tetraspanin CD9 were lower after extended treatment with the DPP-4 inhibitors; less of the CD9 was seen at the plasma membrane after prolonged exposure to sitagliptin. Because both associated proteins are important for adhesion of iBREC to the extracellular matrix, the observed low CI might be caused by weakened attachment of the cells. From our results, we conclude that extended inhibition of DPP-4 destabilizes the barrier formed by microvascular REC and that DPP-4 inhibitors like sitagliptin do not counteract or enhance a VEGF-A165-induced barrier dysfunction as frequently observed in DME.

Prediction of nodal involvement in breast cancer based on multiparametric protein analyses from preoperative core needle biopsies of the primary lesion.

PURPOSE: Identification of molecular characteristics that are useful to define subgroups of patients fitting into differential treatment schemes is considered a most promising approach in cancer research. In this first study of such type, we therefore investigated the potential of multiplexed sandwich immunoassays to define protein expression profiles indicative of clinically relevant properties of malignant tumors. EXPERIMENTAL DESIGN: Lysates prepared from large core needle biopsies of 113 invasive breast carcinomas were analyzed with bead-based miniaturized sandwich immunoassays specific for 54 preselected proteins. RESULTS: Five protein concentrations [fibroblast growth factor-2 (FGF-2), Fas, Fas ligand, tissue inhibitor of metalloproteinase-1, and RANTES] were significantly different in the groups of patients with or without axillary lymph node metastasis. All 15 protein parameters that resulted in P values <0.2 and other diagnostic information [estrogen receptor (ER) status, tumor size, and histologic grading] were analyzed together by multivariate logistic regression. This yielded sets of five (FGF-2, Fas, Fas ligand, IP10, and PDGF-AB/BB) or six (ER staining intensity, FGF-2, Fas ligand, matrix metalloproteinase-13, PDGF-AB/BB, and IP10) parameters for which receiver-operator characteristic analyses revealed high sensitivities and specificities [area under curve (AUC) = 0.75 and AUC = 0.83] to predict the nodal status. A similar analysis including all identified parameters of potential value (15 proteins, ER staining intensity, T) without selection resulted in a receiver-operator characteristic curve with an AUC of 0.87. CONCLUSION: We clearly showed that this approach can be used to quantify numerous proteins from breast biopsies accurately in parallel and define sets of proteins whose combined analyses allow the prediction of nodal involvement with high specificity and sensitivity.

CD9 promotes adeno-associated virus type 2 infection of mammary carcinoma cells with low cell surface expression of heparan sulphate proteoglycans.

Recombinant adeno-associated virus (AAV) is a promising non-pathogenic vector in the emerging field of gene therapy. For AAV serotype 2 (AAV-2) infection, experimental evidence points to an involvement of heparan sulphate proteoglycans (HSPG), but also to the existence of additional receptors. We investigated a potential role of the tetraspanin CD9 in AAV-2 infection of breast cancer cells mainly because it binds to the heparin-binding EGF-like growth factor, suggesting that it may also interact with a heparin-binding virus. Among breast cancer cell lines, expression of HSPG or potential AAV-2 (co)-receptors was not found to correlate with transduction efficiency. In complete accordance with the role of CD9, blocking with anti-CD9 antibodies resulted in drastically decreased AAV-2 transduction efficiencies in cell lines with low expression of HSPG. Furthermore, specific inhibition of CD9 expression with siRNA resulted in fewer transgene-positive cells, whereas overexpression of CD9 in the breast cancer cell line T47D as well as in BT8Ca and BT12Ca rat glioma cells (with low background expression of HSPG and CD9) increased the number of AAV-transduced cells. The minimal epitope recognized by antibody 72F6, which most efficiently blocked AAV-mediated transgene expression, was deduced from the specific binding to peptides immobilized on colour-encoded microspheres consisting of the amino acid sequence PKKDV located in the large extracellular loop of CD9. Our results clearly point to an involvement of CD9 in the attachment, uptake or processing of AAV-2 by target cells expressing low amounts of HSPG, which may help to define cell populations accessible in AAV-based therapeutic applications.

Tetraspanin CD9 is involved in the migration of retinal microvascular endothelial cells.

Members of the tetraspanin protein family are modulators of several fundamental cellular processes in various cell types. However, expression and function of these proteins have not been studied in microvascular endothelial cells despite their (patho-)physiological importance. Western blotting, FACS or RT-PCR analyses confirmed that CD9 and other tetraspanins are expressed in immortalized microvascular endothelial cells of the bovine retina (iBREC). In subconfluent cultures, most of the detected CD9 was located intracellularly as well as in the plasma membrane at cell-cell contact sites and in long spike-like extensions, whereas cells in confluent cultures predominantly showed plasma membrane staining. In wound healing assays, CD9 delocalized from the plasma membrane to its intracellular compartment in cells located at the gap border, and the gap closure was retarded by the addition of an anti-CD9 antibody. Migration of iBREC towards fibronectin and their adhesion to fibronectin were also strongly inhibited in the presence of an anti-CD9 antibody whereas other anti-tetraspanin antibodies had no effect. In summary, iBREC express members of the tetraspanin family of which CD9 was demonstrated to have a function in migration and adhesion of these cells.

Molecular targets of ovarian carcinomas with acquired resistance to platinum/taxane chemotherapy.

Ovarian cancer of epithelial origin remains one of the most lethal malignancies despite response rates of more than 80% in first-line combination chemotherapy with platinum drugs and taxanes following surgery. Poor overall prognosis is mainly due to acquired resistance of the recurring tumor mass to initially used and other chemotherapeutic agents. Therefore, novel therapeutic approaches are based on concepts to prevent (improvement of tumor exposure to drugs) or circumvent drug resistance, e.g. with new drugs structurally related to the currently used cytotoxic agents, other types of cytotoxic substances, or with target-specific novel drugs interfering with signaling and apoptotic pathways. In addition, acquired molecular characteristics of drug resistant ovarian carcinoma cells can be defined by expression profiling at different stages of therapy and might be used as specific targets for tumor-suppressing drugs and prodrugs containing cytotoxic components. Revelation of mechanistic details of drug resistance also provides the basis for the development of therapies with novel or conventional antitumor drugs in combination with specific inhibitors able to re-establish chemosensitivity. In this review, we summarize novel approaches in the treatment of ovarian cancer progressed to drug resistant stages and focus on the discussion of recently reported experimental and early clinical results with potentially useful strategies to overcome or modulate acquired drug resistance.

Chemotherapeutic agents enhance AAV2-mediated gene transfer into breast cancer cells promoting CD40 ligand-based immunotherapy.

PURPOSE: Supplementing conventional treatment with gene therapy to induce an immune response might be beneficial to cancer patients. In this study, we evaluated the efficiency of transduction of breast cancer cells with recombinant adeno-associated virus (rAAV) and effects of cytotoxic agents used in chemotherapy. Furthermore, the capacity of tumor cells expressing transgenic CD40 ligand (CD40L) to stimulate dendritic cells was measured. METHODS: Breast cancer cell lines were infected with a rAAV encoding the enhanced green fluorescent protein (EGFP) or murine CD40L and transgene expression was analyzed by flow cytometry. Stimulation of isolated human dendritic cells by CD40L-expressing tumor cells was quantified by measuring secreted interleukin 12. RESULTS: Infection with an EGFP-encoding rAAV resulted in variable fractions (14-93%, mean 42%) of transgene-expressing cells. Pre-incubation of MM 157, MM 231, and MCF7 cells with epirubicin or carboplatin substantially increased AAV-mediated transgene expression. rAAV/CD40L was used to generate CD40L-transgenic tumor cells, which specifically activated immature dendritic cells, as confirmed by blocking with an antibody binding to CD40L. CONCLUSIONS: The efficiency of rAAV-mediated gene transfer into breast cancer cells is significantly higher than previously reported and can be further enhanced by co-administration of chemotherapeutic agents. We also confirmed that breast cancer cells can activate human dendritic cells after infection with a CD40L-encoding rAAV.

TGFbeta induces transdifferentiation of iBREC to alphaSMA-expressing cells.

Transforming growth factor beta (TGFbeta) both inhibits proliferation of macrovascular endothelial cells and promotes their transdifferentiation to alpha-smooth-muscle-actin (alphaSMA)-expressing mesenchymal cells in vitro. Recently, we have confirmed that proliferation of immortalized bovine retinal microvascular endothelial cells (iBREC) is strongly inhibited by TGFbeta2. We now demonstrate a complete transition of both parental iBREC and single cell-derived subclones from cobblestone morphology to a ragged appearance as a consequence of incubation for a few days with 10 ng/ml TGFbeta1 or TGFbeta2. Depending on the type of culture medium, 5-40% of these cells strongly expressed alphaSMA after approximately 6 days whereas expression of the endothelial cell-specific marker proteins von Willebrand factor and VE Cadherin (CD144) declined. Expression of alphaSMA, associated with formation of stress fibers, was first detected in single cells and then spread to adjacent cells, and declined slowly after prolonged cultivation in medium without TGFbeta2. However, re-constitution of vWF expression was not observed. TGFbeta2-induced phenotypic alterations were specific, as they were not caused by treatment of iBREC with VEGF, IGF-1 or bFGF. Induction of alphaSMA expression but not effects on morphology was strongly inhibited by bFGF, whereas IGF-1 enhanced TGFbeta2-induced alphaSMA expression. These findings may have an important impact on the understanding of development of microvascular complications of diabetes such as diabetic retinopathy.

Safety of monoclonal antibodies and related therapeutic proteins for the treatment of neovascular macular degeneration: addressing outstanding issues.

INTRODUCTION: The vascular endothelial growth factor (VEGF) inhibitors most widely used to treat neovascular age-dependent macular degeneration (nAMD) are different proteins with structural features potentially relevant to adverse effects (AEs). Two of these are also established in cancer therapy (with higher dosages and AEs). The importance of ocular AE and extraocular activities is still a subject of controversy and ongoing research. AREAS COVERED: Potential risks of intraocular VEGF inhibition based on prospective studies, in vitro investigations, pharmacokinetics, and hints from anti-cancer treatment. EXPERT OPINION: nAMD is a frequently observed chronic clinical condition severely affecting the visual function of elderly persons. Intravitreal injection of VEGF-inactivating proteins is highly effective to prevent loss of vision. Anti-VEGF therapy is well tolerated, and low rates of ocular and systemic AEs in smaller trials suggest a very high benefit/risk ratio. The proteins established in nAMD therapy show similar efficacies. In the controversy over the off-label use of bevacizumab purely on grounds of much lower cost, the small, but potentially relevant differences between the available drugs are easily either dramatized (by pharmaceutical companies) or trivialized (by health insurances) and even political interference is involved. Facing the lack of a convincing body of evidence regarding safety, further long-term study results seem necessary.