American Association for Cancer Research

June 15 Cancer Research Highlights

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Selected Articles from the June 15, 2008 Issue

The articles referenced in this Highlights section will be available online in HTML and PDF formats to all interested users at no charge until the next issue of Cancer Research is published. Click on the article title to view the complete article.

View the Table of Contents for the June 15 issue of Cancer Research.


Promotor Methylation in Familial and Sporadic Cancers

Joensuu et al.

Page 4597

Epigenetic changes such as DNA methylation may occur at the earliest stages of tumorigenesis and many tumor suppressor genes are inactivated by methylation in their promoter regions. These changes have been well characterized in sporadic colorectal and endometrial carcinomas, but information on familial cancer is limited. Joensuu and colleagues investigated 24 tumor suppressor genes for promoter methylation in a large series of familial and sporadic tumors and found patterns of methylation based on tumor type (colorectal versus endometrial carcinomas) and familial versus sporadic cancer type. Furthermore, promoter methylation is strongly influenced by the methylation status of the DNA mismatch repair gene MLH1, which has been shown to be important in sporadic colorectal and endometrial carcinomas. Identification of epigenetic patterns of promoter methylation in these familial cancers increases our understanding of the developmental mechanisms of such cancers.  
 

TMEM18 Enhances the Tropism of NSCs for Glioma Cells

Jurvansuu et al.

Page 4614

Current glioma therapies are ineffective due to the invasiveness of glioma cells. Neural stem cells (NSCs) have an intrinsic tropism for sites of brain injury, including gliomas, providing a potential treatment strategy. Jurvansuu and colleagues performed a cDNA expression library screening to identify candidate genes that, once overexpressed, would enhance the tropism of NSCs for gliomas. They show that overexpression of the previously unannotated gene encoding transmembrane protein 18 (TMEM18) increases the migration capacity of NSCs and neural precursor cells toward glioblastoma cells in vitro and in the rat brain. Furthermore, inactivation of the TMEM18 gene results in almost complete loss of migration activity in these cells. Thus TMEM18 is a potential candidate for use in NSC-based glioma therapy.  


RAB23 Expression in Diffuse-Type Gastric Cancer

Hou et al.

Page 4623

Recurrent genomic amplifications and deletions are frequently observed in primary cancers, but identifying specific oncogenes and tumor suppressor genes within these regions can be challenging due to their large sizes. Using high-resolution array-based comparative genomic hybridization (aCGH) and gene expression profiling, Hou and colleagues targeted focal high-level amplifications in cancer cell lines, and identified RAB23 as an amplified and over -expressed Chr 6p11p12 gene associated with diffuse-type gastric cancer. These results demonstrate that investigating focal chromo -somal amplifications by combining high-resolution aCGH with expression profiling is a powerful strategy for identifying novel cancer genes in regions of recurrent chromosomal aberration. 


Zhang et al. Zhang and colleagues have identified a tumorigenic subpopulation characterized as LinCD29HCD24H within a unique p53-null mammary tumor model as demonstrated by limiting dilution transplantation experiments into the cleared mammary fat pads of syngeneic mice. Microarray analysis suggests that genes involved in epigenetic regulation play an important role in regulating the cell fate of these tumor-initiating cells. Increased expression of DNA damage response genes may help explain the resistance of cancer stem cells to chemo- and radiation therapy, and provides a basis for future studies designed to decrease therapeutic resistance and improve treatment outcome. 


Paracrine Signals in Prostate Regression

Placencio et al.

Page 4709

Patients with prostate cancer unresponsive to androgen ablation therapy are left with limited treatment options. Placencio and colleagues studied the cooperation between TGF-β, androgen, and Wnt signaling on mouse models aimed at understanding the regression of the prostate following androgen ablation. These studies highlight the importance of stromal TGF-β signaling in regulating paracrine Wnt signaling as a contributor to androgen independence of the prostate epithelia. The cross-talk of stromal-epithelial signaling demonstrates the potential use of a suppressor of the canonical Wnt signaling pathway to augment androgen ablation therapy.  


BIBF 1120: A Highly Efficacious Triple Angiokinase Inhibitor 

Hilberg et al.

Page 4774

Hilberg et al.Signals mediated by receptors for VEGF, FGF, and PDGF are known to contribute to tumor angiogenesis, suggesting that inhibition of these pathways could be of clinical benefit. Hilberg and colleagues demonstrate that the novel indolinone derivative BIBF 1120 potently inhibits the activity of these angiokinases. BIBF 1120 binds to the ATP pocket as evidenced by the structure of cocrystals with the VEGFR-2 kinase. In cell culture, BIBF 1120 inhibits angiokinase signaling pathways and affects proliferation and survival of endothelial cells, pericytes, and smooth muscle cells. In human tumor xenograft models in mice, BIBF 1120 administered orally inhibits angiogenesis, tumor perfusion, and tumor growth. This compound is currently being investigated in advanced clinical trials in cancer patients.


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