The Mammalian target of rapamycin inhibitors in breast cancer: current evidence and future directions.

The Mammalian target of rapamycin inhibitors in breast cancer: current evidence and future directions.

Anticancer Res. 2013 Jan;33(1):21-8

Authors: Malaguti P, Vari S, Cognetti F, Fabi A

Abstract
Mammalian target of rapamycin (mTOR) is a crucial mediator of tumor progression and may be a promising target in a significant proportion of patients with breast cancer. More specifically, the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT)/mTOR pathway plays a critical role in multiple cellular functions including metabolism, proliferation, growth and survival. This pathway is higly active in many types of cancer and is linked to resistance to many types of therapy. Direct blockade of the mTOR pathway is a new area in breast cancer therapy, with the potential to modulate growth factor- and estrogen-dependent and estrogen-independent pathways, which contribute to the pathogenesis and progression of tumors. Thus, inhibitors of mTOR are of interest as potential therapeutic agents for patients with breast cancer, everolimus and temsirolimus being the main representatives of this category. This review of the literature analyzes the available data emerging from trials and evaluates the efficacy and safety of mTOR inhibitors in all subtypes of breast cancer.

PMID: 23267124 [PubMed - in process]

chir-258 dovitinib dna-pk

Tetraploidization increases sensitivity to Aurora B kinase inhibition.

Related Articles

Tetraploidization increases sensitivity to Aurora B kinase inhibition.

Cell Cycle. 2012 Jul 1;11(13):2567-77

Authors: Marxer M, Foucar CE, Man WY, Chen Y, Ma HT, Poon RY

Abstract
Aurora kinases are overexpressed in many cancers and are targets for anticancer drugs. The yeast homolog of Aurora B kinase, IPL1, was found to be a ploidy-specific lethality gene. Given that polyploidization is a common feature of many cancers, we hypothesized polyploidization also sensitizes mammalian cells to inhibition of Aurora kinases. Using two models of apparent diploid vs. tetraploid cell lines (one based on the hepatocellular carcinoma cell line Hep3B and another on untransformed mouse fibroblasts), we found that tetraploid cells were more sensitive to Aurora B inhibition than their diploid counterparts. Apoptosis could be induced in tetraploid cells by two different Aurora B inhibitors. Furthermore, tetraploid cells were sensitive to Aurora B inhibition but were not affected by Aurora A inhibition. Interestingly, the underlying mechanism was due to mitotic slippage and the subsequent excessive genome reduplication. In support of this, abolition of cytokinesis with dihydrocytochalasin B resulted in similar effects on tetraploid cells as Aurora B inhibition. These results indicate that inhibition of Aurora B or cytokinesis can promote apoptosis effectively in polyploid cancer cells.

PMID: 22722494 [PubMed - in process]

chir-258 dovitinib dna-pk

The Mammalian target of rapamycin inhibitors in breast cancer: current evidence and future directions.

The Mammalian target of rapamycin inhibitors in breast cancer: current evidence and future directions.

Anticancer Res. 2013 Jan;33(1):21-8

Authors: Malaguti P, Vari S, Cognetti F, Fabi A

Abstract
Mammalian target of rapamycin (mTOR) is a crucial mediator of tumor progression and may be a promising target in a significant proportion of patients with breast cancer. More specifically, the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT)/mTOR pathway plays a critical role in multiple cellular functions including metabolism, proliferation, growth and survival. This pathway is higly active in many types of cancer and is linked to resistance to many types of therapy. Direct blockade of the mTOR pathway is a new area in breast cancer therapy, with the potential to modulate growth factor- and estrogen-dependent and estrogen-independent pathways, which contribute to the pathogenesis and progression of tumors. Thus, inhibitors of mTOR are of interest as potential therapeutic agents for patients with breast cancer, everolimus and temsirolimus being the main representatives of this category. This review of the literature analyzes the available data emerging from trials and evaluates the efficacy and safety of mTOR inhibitors in all subtypes of breast cancer.

PMID: 23267124 [PubMed - in process]

rad001 ecdysone chir-258

DREF is involved in the steroidogenesis via regulation of shadow gene.

DREF is involved in the steroidogenesis via regulation of shadow gene.

Am J Cancer Res. 2012;2(6):714-25

Authors: Park JS, Choi YJ, Thao DT, Kim YS, Yamaguchi M, Yoo MA

Abstract
The Drosophila DNA replication-related element-binding factor (dDREF) has been identified as a master regulator of cell proliferation-related genes via its binding to the DRE sequence, 5'-TATCGATA. However, the biological roles of DREF are still to be clarified. Here, we show that DREF mutant females have steroid hormone ecdysone-deficient phenotypes, such as the loss of vitellogenic egg chambers. Furthermore, DREF knockdown in the prothoracic gland of larva prevented pupation and this was rescued via 20-hydroxyecdysone treatment. We found a DRE-like sequence (-625 to -632) in the 5'-flanking region of the Drosophila shadow gene, which catalyzes the conversion of 2-deoxyecdysone to ecdysone, and demonstrated that shadow is a novel target gene of dDREF using quantitative RT-PCR and Chip assays. In addition, we show that the level of dDREF protein correlated with age-related changes in the level of shadow mRNA in the ovaries of wild-type flies. Taken together, our data indicate that dDREF plays a key role in steroid synthesis via regulation of the shadow gene.

PMID: 23226617 [PubMed]

dovitinib dna-pk coxinhibitors

A translocator protein ligand PK11195 shows antigrowth activity in human choriocarcinoma cells.

Related Articles

A translocator protein ligand PK11195 shows antigrowth activity in human choriocarcinoma cells.

Tumour Biol. 2012 Oct;33(5):1505-10

Authors: Takai N, Kira N, Ishii T, Yoshida T, Nishida M, Nishida Y, Nasu K, Takano M, Midori H, Koga S, Narahara H

Abstract
The potential anticancer agent 1-(2-chlorophenyl-N-methylpropyl)-3-isoquinolinecarboxamide (PK11195), a translocator protein ligand (initially described as a ligand for the peripheral benzodiazepine receptor), induces apoptosis in some lines of human tumor cells. We investigated the effect of PK11195 in the choriocarcinoma cell line, BeWo. BeWo cells were treated with various concentrations of PK11195, and changes in cell growth, the cell cycle, apoptosis, and related parameters were examined. A WST-1 assay showed that BeWo cells were sensitive to the growth inhibitory effect of PK11195. In contrast, the nonsite selective ligand diazepam has a little effect on these cells. Cell cycle analysis indicated that exposure to PK11195 decreased the proportion of cells in the S phase and increased the proportion in the G0/G1 phases of the cell cycle. Induction of apoptosis was confirmed by Annexin V staining of externalized phosphatidylserine, by the loss of mitochondrial transmembrane potential, and by antibodies directed against histones from fragmented DNA. This induction occurred in conjunction with the altered expression of genes related to cell growth, malignant phenotype, and apoptosis. These results suggest that PK11195 may serve as a therapeutic agent for the treatment of choriocarcinoma.

PMID: 22528948 [PubMed - indexed for MEDLINE]

dovitinib dna-pk coxinhibitors

Tetraploidization increases sensitivity to Aurora B kinase inhibition.

Related Articles

Tetraploidization increases sensitivity to Aurora B kinase inhibition.

Cell Cycle. 2012 Jul 1;11(13):2567-77

Authors: Marxer M, Foucar CE, Man WY, Chen Y, Ma HT, Poon RY

Abstract
Aurora kinases are overexpressed in many cancers and are targets for anticancer drugs. The yeast homolog of Aurora B kinase, IPL1, was found to be a ploidy-specific lethality gene. Given that polyploidization is a common feature of many cancers, we hypothesized polyploidization also sensitizes mammalian cells to inhibition of Aurora kinases. Using two models of apparent diploid vs. tetraploid cell lines (one based on the hepatocellular carcinoma cell line Hep3B and another on untransformed mouse fibroblasts), we found that tetraploid cells were more sensitive to Aurora B inhibition than their diploid counterparts. Apoptosis could be induced in tetraploid cells by two different Aurora B inhibitors. Furthermore, tetraploid cells were sensitive to Aurora B inhibition but were not affected by Aurora A inhibition. Interestingly, the underlying mechanism was due to mitotic slippage and the subsequent excessive genome reduplication. In support of this, abolition of cytokinesis with dihydrocytochalasin B resulted in similar effects on tetraploid cells as Aurora B inhibition. These results indicate that inhibition of Aurora B or cytokinesis can promote apoptosis effectively in polyploid cancer cells.

PMID: 22722494 [PubMed - in process]

dna-pk coxinhibitors c-met inhibitors

DREF is involved in the steroidogenesis via regulation of shadow gene.

DREF is involved in the steroidogenesis via regulation of shadow gene.

Am J Cancer Res. 2012;2(6):714-25

Authors: Park JS, Choi YJ, Thao DT, Kim YS, Yamaguchi M, Yoo MA

Abstract
The Drosophila DNA replication-related element-binding factor (dDREF) has been identified as a master regulator of cell proliferation-related genes via its binding to the DRE sequence, 5'-TATCGATA. However, the biological roles of DREF are still to be clarified. Here, we show that DREF mutant females have steroid hormone ecdysone-deficient phenotypes, such as the loss of vitellogenic egg chambers. Furthermore, DREF knockdown in the prothoracic gland of larva prevented pupation and this was rescued via 20-hydroxyecdysone treatment. We found a DRE-like sequence (-625 to -632) in the 5'-flanking region of the Drosophila shadow gene, which catalyzes the conversion of 2-deoxyecdysone to ecdysone, and demonstrated that shadow is a novel target gene of dDREF using quantitative RT-PCR and Chip assays. In addition, we show that the level of dDREF protein correlated with age-related changes in the level of shadow mRNA in the ovaries of wild-type flies. Taken together, our data indicate that dDREF plays a key role in steroid synthesis via regulation of the shadow gene.

PMID: 23226617 [PubMed]

dovitinib dna-pk coxinhibitors