A novel breast cancer cell line (RAO-3) was established by transduction of the Q61L mutant RAS into human mammary epithelial cells that were immortalized with catalytic subunit of telomerase (hTERT). The cells displayed anchorage-independent growth and proliferation, and formed human mammary spindle cell carcinoma when injected into nude mice. Chromosome locus 1q22-23 was partially duplicated and inverted on one of the 3 chromosomes present in the cell line. We report here that mutations of chromosome 1q22-23 locus have resulted in the loss of RAB25 expression in the breast cancer cell line. Transduction of RAB25 into the breast cancer cell line arrests anchorage-independent growth. We have also demonstrated loss of RAB25 in human breast tumor tissue. These data suggest that loss of RAB25 might contribute to tumorigenesis of breast cancer, and RAB25 is likely to be an important factor in the development of breast cancer. RAB25 could be used as biological marker of breast cancer and provides a target for gene replacement therapy. ' 2006 Wiley-Liss, Inc. Key words: RAS; RAB25; breast cancerBreast cancer is the most common cancer in North American women. Many genes are considered to contribute to tumorigenesis of the mammary gland, such as RAS, BCL-2 (B-cell Leukemia-2) and NRG1 (Neuregulin1). 1-3 A novel series of human breast cancer cell lines has been established through the use of defined genetic elements in an effort to better define the role of various oncogenes in a stepwise model to tumor progression. 4 Human mammary epithelial cells (HMEC) from healthy individuals undergoing reduction mammoplasty were immortalized by transduction of either the catalytic subunit of telomerase (hTERT) after passage through stasis (RAO-1 cell line) or the human papilloma virus type16 (HPV16) E6/E7 genes. The RAO-1 cell line was then transduced with the Q61L mutant H-RAS gene; RAO-2 is a RAS-transduced derivative cell line of RAO-1 that does not show anchorageindependent growth in soft agar and is not tumorigenic in nude mice. RAO-3 and RAO-4 are human breast cancer cell lines that were derived from RAO-1 after RAS transduction. RAO-3 exclusively gives rise to human mammary spindle cell carcinomas when injected into nude mice. RAO-4 exclusively generates human mammary epithelial carcinoma when injected into nude mice. Previous studies suggested that a critical cytogenetic event on chromosome locus 1q23 was the last significant step to transformation in our RAS-driven model. 4 We confirmed the rearrangement of chromosome 1q22-23 by FISH (fluorescence in situ hybridization) in the RAO-3 cell line. The expression of RAB25, one of the genes that are located in this region, was lost in some of the tumorigenic cell lines that we tested, including RAO-3 and RAO-4.The RAB guanosine triphosphatases (GTPases) (RAS-related in brain) 5 belong to the RAS superfamily of small GTPases. More than 60 different RAB family members have been identified in the human genome. 6,7 The human RAS family consists of 3 protooncogenes, H-RAS, K-RAS and N...

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These results demonstrated that chronic cerebral hypoperfusion could induce sustained up-regulation of VEGF mRNA and protein expression in rat brain, which was correlated with angiogenesis. An absence of corresponding astrocytic reactivity during angiogenesis may be an important factor accounting for structural deficits of the blood-brain barrier and the occurrence of normal-perfusion pressure breakthrough.