Corinne Reimer

Tumor cell growth inhibition by caveolin re-expression in human breast cancer cells.

Cancer development is a multistage process that results from the step-wise acquisition of somatic alterations in diverse genes. Recent studies indicate that caveolin-1 expression correlates with the level of oncogenic transformation in NIH3T3 cells, suggesting that caveolin in caveolae may regulate normal cell proliferation. In order to better understand potential functions of caveolin-1 in cancer development, we have studied expression levels of caveolin-1 in human breast cancer cells, and have found that caveolin expression is significantly reduced in human breast cancer cells compared with their normal mammary epithelial counterparts. When the caveolin cDNA linked to the CMV promoter is transfected into human mammary cancer cells having no detectable endogenous caveolin, overexpression of caveolin-1 resulted in substantial growth inhibition, as seen by the 50% decrease in growth rate and by ∼l5-fold reduction in colony formation in soft agar. In addition, characterization of caveolin-1 expression during cell cycle progression indicates that expression of α-caveolin-1 is regulated during cell cycle. Furthermore p53-deficient cells showed a loss in caveolin expression. In summary, the overall expression patterns, its ability to inhibit tumor growth in culture, its regulation during the cell cycle, and the loss of expression in p53-deficient cells all are consistent with an important growth regulating function for caveolin-1 in normal human mammary cells, that needs to be repressed in oncogenic transformation and tumor cell growth.

A Human Monoclonal Anti-ANG2 Antibody Leads to Broad Antitumor Activity in Combination with VEGF Inhibitors and Chemotherapy Agents in Preclinical Models

Localized angiopoietin-2 (Ang2) expression has been shown to function as a key regulator of blood vessel remodeling and tumor angiogenesis, making it an attractive candidate for antiangiogenic therapy. A fully human monoclonal antibody (3.19.3) was developed, which may have significant pharmaceutical advantages over synthetic peptide-based approaches in terms of reduced immunogenicity and increased half-life to block Ang2 function. The 3.19.3 antibody potently binds Ang2 with an equilibrium dissociation constant of 86 pmol/L, leading to inhibition of Tie2 receptor phosphorylation in cell-based assays. In preclinical models, 3.19.3 treatment blocked blood vessel formation in Matrigel plug assays and in human tumor xenografts. In vivo studies with 3.19.3 consistently showed broad antitumor activity as a single agent across a panel of diverse subcutaneous and orthotopic xenograft models. Combination studies of 3.19.3 with cytotoxic drugs or anti–vascular endothelial growth factor agents showed significant improvements in antitumor activity over single-agent treatments alone with no apparent evidence of increased toxicity. Initial pharmacokinetic profiling studies in mice and nonhuman primates suggested that 3.19.3 has a predicted human half-life of 10 to 14 days. These studies provide preclinical data for 3.19.3 as a potential new antiangiogenic therapy as a single agent or in combination with chemotherapy or vascular endothelial growth factor inhibitors for the treatment of cancer. Mol Cancer Ther; 9(1); 145–56

Altered regulation of cyclin G in human breast cancer and its specific localization at replication foci in response to DNA damage in p53+/+ cells.

Cyclin G, a recent addition to the cyclin family, was initially identified in screens for new src kinase family members and soon thereafter by differential screening for transcriptional targets of the tumor suppressor gene, p53. We have identified cyclin G as being overexpressed in breast and prostate cancer cells using differential display polymerase chain reaction screening. We demonstrate here that cyclin G is overexpressed in human breast and prostate cancer cells and in cancer cells in situ from tumor specimens. Cyclin G expression was tightly regulated throughout the cell cycle in normal breast cells, peaking at the S and G2/M phases of the cell cycle with lower levels in G1. The cell cycle-dependent expression was absent in breast cancer cells. Following DNA damage in normal p53+/+ cells, cyclin G is triggered to cluster in discrete nuclear DNA replication foci that contain replication-associated proteins such as proliferating cell nuclear antigen (PCNA). While p53−/− cells displayed a faint cyclin G nuclear staining pattern, there was no increased expression and no change in distribution of the staining pattern after DNA damage. The specific subcellular localization of cyclin G at DNA replication foci provides an additional link between p53-mediated growth arrest and cell cycle regulation and suggests that cyclin G may act as an effector of p53-mediated events by functional association with replication foci protein(s).

Abstract 2459: Discovery of small molecule TAK1 inhibitors with antiproliferative activity in cell lines derived from hematological malignancies.

Transforming growth factor β-activated kinase 1 (TAK1), a member of the MAPKKK family, is a key mediator of proinflammatory and stress signaling. It was shown previously that inhibition of TAK1 via the use of siRNA or small-molecule kinase inhibitors can inactivate NF-κB, down-regulate p38, and activate the intrinsic caspase pathway, resulting in profound induction of apoptosis. Herein we report the discovery of 5-fluoro-4-(imidazo[1,2-b]pyridazin-3-yl)-N-phenylpyrimidin-2-amines as TAK1 ATP competitive small molecule inhibitors. These compounds inhibit the kinase activity of TAK1 in vitro with low nanomolar potency. Evidence is presented that supports a mechanism of action consistent with inhibition of TAK1 kinase activity within the NF-κB pathway. Optimization of potency and selectivity for this series from hit to lead will be discussed, including the structure-based design and crystallographic determination of the binding mode. The outcome of efforts aimed at improving the in vivo pharmacokinetics of compounds is described. Results of kinase selectivity profiling for both an in vitro probe compound - AZ TAK1 - and an in vivo probe compound will be presented. Furthermore, we report low nanomolar antiproliferative activities in cell lines derived from Haematological Malignancies for these compounds. This cellular activity profile is suggesting that TAK1 inhibition presents therapeutic potential in Haematological Cancers. Citation Format: Dorin Toader, Jamal C. Saeh, Nin Guan, Francoise Powell, Raymond Chen, Corinne Reimer, Kate Byth. Discovery of small molecule TAK1 inhibitors with antiproliferative activity in cell lines derived from hematological malignancies. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2459. doi:10.1158/1538-7445.AM2013-2459