Showing papers by "Setsuko K. Chambers published in 2005"
TL;DR: The study identified GAPDH as an AUBP abundant in Hey cells, where it binds to CSF-1 ARE that imparts mRNA decay, leading to CSf-1 overexpression and increased metastatic properties seen in ovarian cancer.
Abstract: The overexpression of the colony-stimulating factor-1(CSF-1) by epithelial ovarian cancer cells enhances invasiveness and metastatic properties, contributing to the poor prognosis of the patients. It has been suggested that CSF-1 3' untranslated region containing AU-rich elements (ARE) could regulate CSF-1 posttranscriptional expression and be responsible for its aberrant abundance in such cancer cells. In this study, normal (NOSE.1) and malignant (Hey) ovarian epithelial cells were used to examine CSF-1 expression and regulation. CSF-1 overexpression in Hey cells was found to associate with increased invasiveness, motility, urokinase activity, and virulence of tumorigenicity, compared with NOSE.1 cells, which expressed little CSF-1. CSF-1 ARE was further found to serve as an mRNA decay element that correlates with down-regulation of protein translation. Moreover, such down-regulation was found more prominent in NOSE.1 than in Hey cells, suggesting differences in posttranscriptional regulation. As a variety of trans-acting factors [AU-binding protein (AUBP)] are known to modulate messenger stability through binding to such elements, we examined the protein content of both cell lines for their ability to bind the CSF-1 ARE. Our results strongly suggested the abundance of such AUBP activity in Hey cells. We isolated a 37-kDa AUBP, which was identified as glyceraldehyde-3-phosphate dehydrogenase (GAPDH). To summarize, our study identified GAPDH as an AUBP abundant in Hey cells, where it binds to CSF-1 ARE that imparts mRNA decay. These data suggest that GAPDH binding to CSF-1 ARE sequence prevents CSF-1 mRNA decay and subsequent down-regulation of CSF-1 protein translation, leading to CSF-1 overexpression and increased metastatic properties seen in ovarian cancer.
98 citations
22 citations
TL;DR: This model provides tumors of significant size and organ diversity which retain their phenotype early in tumorigenesis allowing an early endpoint to assess efficacy of novel treatments and modulation of c-fms proto-oncogene expression via oral administration to SCID mice with subsequent correlation to IHC staining.
Abstract: Although proto-oncogene expression has been shown to correlate with clinical outcome in breast carcinoma, an experimental model has not been proposed to study this phenomenon in vivo. In addition, the ability to modulate this proto-oncogene in vivo to correlate with phenotypic behavior has not been determined. Utilizing an intraperitoneal model for metastatic spread with BT20 human breast carcinoma cells, clonally expanded cells expressing five fold higher c-fms protein were compared with parent BT20 cells as well as an underexpressing clone using intrasplenic injection following left flank cut-down in female nude and Severe combined immunodeficient (SCID) mice. Athymic BALB/c nude and SCID animals were observed for clinical evidence of tumorigenicity with necropsy performed at either 50 or 80 days unless compromised earlier. Immunohistochemistry (IHC) of the harvested tumors was performed to correlate c-fms expression from its original in vitro culture to the in vivo model. At day 50, differences in primary tumor take and spread to the pelvis were already evident favoring the c-fms over-expression group with IHC of these tumors revealing significantly higher intensity of staining for c-fms, (mean H score of 205 vs. 43 in the over-expression and parent groups, respectively). At day 80, tumor take and spread was comparable; however, tumor size in the over-expression group was significantly larger than the parent and under-expressing group in both the BALB/c and SCID experiments. Modulation of c-fms proto-oncogene expression was also achieved using the anti-glucocorticoid, RU-486, via oral administration to SCID mice with subsequent correlation to IHC staining. This model thus provides tumors of significant size and organ diversity which retain their phenotype early in tumorigenesis allowing an early endpoint to assess efficacy of novel treatments.
16 citations