We have established a line of transgenic mice expressing the A. victoria green fluorescent protein (GFP) under the control of the promoter for vascular endothelial growth factor (VEGF). Mice bearing the transgene show green cellular fluorescence around the healing margins and throughout the granulation tissue of superficial ulcerative wounds. Implantation of solid tumors in the transgenic mice leads to an accumulation of green fluorescence resulting from tumor induction of host VEGF promoter activity. With time, the fluorescent cells invade the tumor and can be seen throughout the tumor mass. Spontaneous mammary tumors induced by oncogene expression in the VEGF-GFP mouse show strong stromal, but not tumor, expression of GFP. In both wound and tumor models the predominant GFP-positive cells are fibroblasts. The finding that the VEGF promoter of nontransformed cells is strongly activated by the tumor microenvironment points to a need to analyze and understand stromal cell collaboration in tumor angiogenesis.
To explore the molecules associated with gastric adenocarcinoma, we used the gene expression profile database of various human tissues and identified TRIM31 upregulated in both patients with chronic gastritis and stomach cancer. TRIM31 is a new member of RBCC proteins composed of RING finger, B-box and coiled-coil domains. We characterized TRIM31 biochemically and found it possess properties in common with other RBCC proteins, such as occurrence of alternative splicing transcripts, in vitro autoubiquitylating activity and a tendency to homo-oligomerize. The primary localization site of TRIM31 is the cytoplasm but some fraction is potentially associated with the mitochondria. TRIM31 overexpression suppresses colony formation of HCT116 cells while knockdown of its expression with short interfering RNAs (siRNAs) consistently tends to enhance growth of AsPC-1 cells slightly. Thus, TRIM31 is a characteristic RBCC protein with the ability to regulate cell proliferation negatively and may be a potential biomarker of gastric cancer as it is overexpressed from the early stage of gastric carcinogenesis.
In search for a new anticancer drug target, we explored genes involved in colon adenocarcinoma development through dysregulation of a signal transduction pathway. By using the gene expression profile database, we found protein phosphatase 1H (PPM1H), belonging to the protein phosphatase 2C (PP2C) family, upregulated in colon adenocarcinomas compared with normal colon tissues. RT-PCR analysis verified the elevated level of PPM1H expression in colon cancer cell lines relative to a normal colon cell line. PPM1H encodes a protein with a molecular mass of approximately 50 kDa that resides in the cytoplasm. PPM1H fused with maltose-binding protein expressed in E. coli exhibited phosphatase activity characteristic of the PP2C family. Co-immunoprecipitation coupled with mass spectrometry analysis identified CSE1L, a proliferation and apoptosis-related protein, as a PPM1H-interacting protein. Native, but not inactive, PPM1H expressed in HeLa cells increased the mobility of CSE1L on SDS gels and a similar mobility shift was observed for purified CSE1L after treatment with PPM1H in vitro, supporting the notion that CSE1L is a substrate of PPM1H. Dominant negative PPM1H protected HeLa cells from cell death triggered by staurosporine or taxol. Additionally, knockdown of PPM1H expression with small interfering RNAs suppressed the growth of MCF-7 cells weakly but consistently. PPM1H controls cell cycle and proliferation of cancer cells potentially through dephosphorylation of CSE1L and might be a new target of anticancer drugs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.