Search

Tumor-angiogenesis is the multi-factorial process of sprouting of endothelial cells (EC) into micro-vessels to provide tumor cells with nutrients and oxygen. To explore miRNAs as therapeutic angiogenesis-inhibitors, we performed a functional screen to identify miRNAs that are able to decrease EC viability. We identified miRNA-7 (miR-7) as a potent negative regulator of angiogenesis. Introduction of miR-7 in EC resulted in strongly reduced cell viability, tube formation, sprouting and migration. Application of miR-7 in the chick chorioallantoic membrane assay led to a profound reduction of vascularization, similar to anti-angiogenic drug sunitinib. Local administration of miR-7 in an in vivo murine neuroblastoma tumor model significantly inhibited angiogenesis and tumor growth. Finally, systemic administration of miR-7 using a novel integrin-targeted biodegradable polymeric nanoparticles that targets both EC and tumor cells, strongly reduced angiogenesis and tumor proliferation in mice with human glioblastoma xenografts. Transcriptome analysis of miR-7 transfected EC in combination with in silico target prediction resulted in the identification of OGT as novel target gene of miR-7. Our study provides a comprehensive validation of miR-7 as novel anti-angiogenic therapeutic miRNA that can be systemically delivered to both EC and tumor cells and offers promise for miR-7 as novel anti-tumor therapeutic.

[This corrects the article DOI: 10.1371/journal.pone.0043569.].

Malignant melanoma is an aggressive form of skin cancer with poor prognosis. Despite improvements in awareness and prevention of this disease, its incidence is rapidly increasing. MicroRNAs (miRNAs) are a class of small RNA molecules that regulate cellular processes by repressing messenger RNAs (mRNAs) with partially complementary target sites. Several miRNAs have already been shown to attenuate cancer phenotypes, by limiting proliferation, invasiveness, tumor angiogenesis, and stemness. Here, we employed a genome-scale lentiviral human miRNA expression library to systematically survey which miRNAs are able to decrease A375 melanoma cell viability. We highlight the strongest inhibitors of melanoma cell proliferation, including the miR-15/16, miR-141/200a and miR-96/182 families of miRNAs and miR-203. Ectopic expression of these miRNAs resulted in long-term inhibition of melanoma cell expansion, both in vitro and in vivo. We show specifically miR-16, miR-497, miR-96 and miR-182 are efficient effectors when introduced as synthetic miRNAs in several melanoma cell lines. Our study provides a comprehensive interrogation of miRNAs that interfere with melanoma cell proliferation and viability, and offers a selection of miRNAs that are especially promising candidates for application in melanoma therapy.

A goal of oncology is to predict chemosensitivity of tumors. This approach assumes that in a patient all tumor deposits are homogeneous. We have tested the heterogeneity between several samples of the same liver metastasis (LM; intrametastatic heterogeneity) or between multiple LM (intermetastatic heterogeneity) from colorectal cancer in a single patient. In 16 untreated patients, several fragments of LM and nontumorous liver were collected. Heterogeneity to anticancer drug treatment was assessed in vitro on primary tissue cultures on poly-HEMA-coated surface with or without the topoisomerase-I inhibitor metabolite SN-38. Heterogeneity of response to SN-38 was observed in 55% of cases from one fragment to another in the same LM and in 64% of cases from one LM to another in the same patient. Allelic losses were characterized on 5q, 8p, 17p, 18q, 22q using 29 microsatellites markers. Seven patients (58%) had a perfect homogeneity for allelic losses in their LM whereas 3 (21%) had intrametastatic and 2 (18%) had intermetastatic heterogeneity. The analysis of gene expression was carried out by real time RT-PCR quantification using specific probes for TS, TOPO1, ERCC1, and CES2. Level expression of genes tested appeared heterogeneous with average variations of 57(+ or - 23)%, 52(+ or - 18)%, 53(+ or - 18)%, 56(+ or - 16)% for TS, TOPO1, ERCC1, and CES2 respectively for intermetastatic variability and 47(+ or - 26)%, 36(+ or - 14)%, 38(+ or - 19)%, and 56(+ or - 29)%, respectively for intrametastatic variability. Our results demonstrate intermetastatic and intrametastatic heterogeneity suggesting that pretherapeutic analysis of a single tumor biopsy is likely to lead to a misinterpretation of sensitivity to anticancer treatment.

Multicellular tumor spheroids closely mimic the 3D organization of avascular microregions within tumors and thereby represent a valuable model for the evaluation of anticancer drugs. In this study, we performed a 3D analysis of the response to the CDC25 phosphatase inhibitor IRC-083864 in HCT116 spheroids. Continuous exposure to IRC-083864 strongly inhibits the growth of spheroids and is shown to correlate with a decrease in Ki-67 positive cells. The cytotoxicity induced by IRC-083864 was examined by two-photon laser microscopy imaging and 3D reconstruction. Visualization in 3D allowed us to demonstrate that IRC-083864 treatment results in the inhibition of mitosis and induces cell death specifically localized in the outer proliferative cell layers of the spheroid structure. These results emphasize the importance of 3D models and of in toto analysis for the evaluation of anticancer drugs cytotoxicity.

CDC25 phosphatases are key actors in cyclin-dependent kinases activation whose role is essential at various stages of the cell cycle. CDC25 expression is upregulated in a number of human cancers. CDC25 phosphatases are therefore thought to represent promising novel targets in cancer therapy. Here, we report the identification and the characterization of IRC-083864, an original bis-quinone moiety that is a potent and selective inhibitor of CDC25 phosphatases in the low nanomolar range. IRC-083864 inhibits cell proliferation of a number of cell lines, regardless of their resistance to other drugs. It irreversibly inhibits cell proliferation and cell cycle progression and prevents entry into mitosis. In addition, it inhibits the growth of HCT-116 tumor spheroids with induction of p21 and apoptosis. Finally, IRC-083864 reduced tumor growth in mice with established human prostatic and pancreatic tumor xenografts. This study describes a novel compound, which merits further study as a potential anticancer agent.

Cell cycle regulators, such as the CDC25 phosphatases, are potential targets for the development of new anticancer drugs. Here we report the identification and the characterization of BN82685, a quinone-based CDC25 inhibitor that is active in vitro and in vivo. BN82685 inhibits recombinant CDC25A, B, and C phosphatases in vitro. It inhibits the growth of human tumor cell lines with an IC(50) in the submicromolar range, independently of their resistance to chemotherapeutic agents. This inhibitory effect is irreversible on both the purified CDC25 enzyme in vitro and on tumor cell proliferation. The specificity of BN82685 towards the CDC25 phosphatases is shown by an increase in cyclin-dependent kinase 1 tyrosine 15 phosphorylation, by the reversion of the mitosis-inducing effect of CDC25B overexpression in HeLa cells, and by the lack of a growth inhibitory effect in an assay based on the use of a CDC25-independent fission yeast model. Finally, when administered p.o., BN82685 is shown to inhibit the growth of the human pancreatic tumor Mia PaCa-2 xenografted in athymic nude mice. BN82685 is therefore a promising new compound targeting CDC25, which confirms the interest of the inhibition of these enzymes as an anticancer therapeutic strategy.

CDC25 dual-specificity phosphatases are essential regulators that dephosphorylate and activate cyclin-dependent kinase/cyclin complexes at key transitions of the cell cycle. CDC25 activity is currently considered to be an interesting target for the development of new antiproliferative agents. Here we report the identification of a new CDC25 inhibitor and the characterization of its effects at the molecular and cellular levels, and in animal models. BN82002 inhibits the phosphatase activity of recombinant human CDC25A, B, and C in vitro. It impairs the proliferation of tumoral cell lines and increases cyclin-dependent kinase 1 inhibitory tyrosine phosphorylation. In synchronized HeLa cells, BN82002 delays cell cycle progression at G1-S, in S phase and at the G2-M transition. In contrast, BN82002 arrests U2OS cell cycle mostly in the G1 phase. Selectivity of this inhibitor is demonstrated: (a) by the reversion of the mitotic-inducing effect observed in HeLa cells upon CDC25B overexpression; and (b) by the partial reversion of cell cycle arrest in U2OS expressing CDC25. We also show that BN82002 reduces growth rate of human tumor xenografts in athymic nude mice. BN82002 is a original CDC25 inhibitor that is active both in cell and animal models. This greatly reinforces the interest in CDC25 as an anticancer target.

As essential cell cycle regulators, the CDC25 phosphatases are currently considered as potential targets for the development of novel therapeutic approaches. Here, we review the function and regulation of CDC25 phosphatases, their involvement in cancer and Alzheimer's disease, and the properties of several recently identified inhibitors.

Oncogenic mutations of the ras gene leading to constitutive activation of downstream effectors have been detected in a wide spectrum of human cancers (pancreas, thyroid, colon, non-small-cell lung cancer). Membrane anchorage of Ras, required for functional activity in signal transduction, is facilitated by post-translational modifications resulting in covalent attachment of a farnesyl group to the cysteine in the C-terminal CAAX motif. This attachment is mediated by farnesyltransferase (FTase). Here, we report a novel FTase inhibitor, BIM-46228, which showed (i) specific inhibition of purified human FTase enzyme, (ii) inhibition of proliferation in vitro in a large spectrum of human tumor cell lines, (iii) inhibition of growth of human tumor xenografts in athymic nude mice treated by per os administration and (iv) the benefits of in vitro combination of its activity with chemotherapy or radiotherapy., (Copyright 2001 Wiley-Liss, Inc.)

Oncogenic mutations of the ras gene leading to constitutive activation of downstream effectors have been detected in a large spectrum of human cancers (pancreas, thyroid, colon and NSCLC). Membrane anchorage of Ras required for functional activity in signal transduction is facilitated by post-translational modifications resulting in covalent attachment of a farnesyl group to the cysteine in the C-terminal CAAX motif. This attachment is mediated by farnesyltransferase (FTase). Here, we report a novel series of potent FTase inhibitors, where the tetrapeptide CAAX motif has been modified by incorporation of a thiazolidine carboxylic acid moiety followed by reduction of the 1st and 2nd peptide bonds to a secondary and tertiary amine, respectively. The C-terminal carboxylate was converted to esters for improved cellular penetration. These compounds showed specific inhibition of purified human FTase enzyme, inhibition of proliferation in vitro in a large spectrum of human tumor cell lines and inhibition of growth of human tumor xenografts in athymic nude mice. In addition, in regard to a panel of cell lines, using the Compare analysis to determine the Pearson coefficient correlation, the anti-proliferative spectrum of BIM-46068 has been shown to be distinct from the profile of typical chemotherapeutic agents., (Copyright 1999 Wiley-Liss, Inc.)