Identification of rat mammary tumor-1 gene (RMT-1), which is highly expressed in rat mammary tumors

Chiou, S Yoo, J Loh, KC Guzman, RC Gopinath, GR Rajkumar, L Chou, YC Yang, J Popescu, NC Nandi, S

S. Chiou et al., Identification of rat mammary tumor-1 gene (RMT-1), which is highly expressed in rat mammary tumors, CANCER LETT, 174(1), 2001, pp. 45-55

38

INGLESE

Article

Onconogenesis & Cancer Research

CANCER LETTERS

0304-3835 → ACNP

174

1

2001

45 - 55

ISI

0304-3835(200112)174:1<45:IORMTG>2.0.ZU;2-S

Full-term pregnancy early in life results in a permanent reduction in lifet ime breast cancer risk in women. Parous rats and mice are also refractory t o chemical carcinogenesis. Therefore, investigation of the differences betw een mammary glands from virgin and parous rats would provide valuable infor mation regarding the protective effects of early full-term pregnancy. In th is report, we examined the gene expression patterns in mammary glands from virgin and parous Lewis rats. Using differential display technology, a nove l 4.2 kb cDNA, designated rat mammary tumor-1 (RMT-1) was isolated. Norther n blot analysis of RMT-1 showed that RMT-1 expression was higher in the pre -pubertal and pubertal stages during rat mammary gland development while it was down-regulated in mammary glands from mature virgin and parous rats. R MT-1 expression was highest in rat mammary cancers compared with either the mammary glands of virgin or parous rats. At the Northern blot sensitivity level, RMT-1 expression was found only in the mammary gland. Northern blot analysis also showed that the expression of this gene was found in 74% of N -methyl-nitrosourea (MNU)-induced mammary cancers while it was not found in MNU-induced cancers from other organs. The examination of the RMT-1 gene s tructure revealed that it consists of five exons spanning 5.9 kb. Using flu orescence in situ hybridization, the gene was localized on rat chromosome 1 band q 43-51. The present data show that there is a correlation between hi gh RMT-1 expression and rat mammary carcinogenesis or decreased RMT-1 expre ssion and parity associated refractoriness to chemically induced mammary ca rcinogenesis. However, whether or not RMT-1 gene has a functional role in t hese processes remains to be investigated. (C) 2001 Elsevier Science Irelan d Ltd. All rights reserved.