Expression of a vitamin D-regulated gene (VDUP-1) in untreated- and MNU-treated rat mammary tissue.
Previous studies showed that the expression of an mRNA corresponding to VDUP-1 was decreased within MNU-induced rat mammary tumors. RNA from mammary tissue was DNase treated and reverse transcribed and the resulting cDNA was amplified using primers designed to amplify VDUP-1 (382 bp fragment) and glyceraldehyde-6-phosphate dehydrogenase (GAPDH) (416 bp fragment). Analysis of mammary cDNA derived from untreated or MNU-treated rats indicated that VDUP-1 expression within tumor tissue was significantly decreased, a finding which agrees with previous Northern blotting experiments. The differential expression was confirmed in tissue sections using an antisense VDUP-1 riboprobe for in situ hybridization studies which demonstrated that VDUP-1 staining in all cell types within tumor tissue was greatly decreased. VDUP-1 mRNA was expressed to a greater extent within epithelial cells and to a much lesser extent within stromal cells, including endothelial cells, in untreated mammary tissue. A significant decrease in VDUP-1 expression was detected as early as six weeks after MNU treatment, before tumors had formed. Bilateral ovariectomy did not alter VDUP-1 expression in untreated mammary tissue and ovariectomy prior to MNU treatment prevented tumor formation, as well as the associated decrease in VDUP-1 expression. The relative expression of VDUP-1 was higher in lung tissue than in adrenal, heart, kidney, liver, mammary, muscle, and ovary. Treatment of a cell line derived from an MNU-induced rat mammary tumor (MNU cells) with 1,25-dihydroxyvitamin D3 resulted in a significant increase in VDUP-1 expression and also inhibited cell growth in the absence of serum. The data are consistent with a role for VDUP-1 in mediating the inhibitory effects of 1,25-dihydroxyvitamin D3 on tumor cell growth.
Yang
X
X
Department of Pharmacology and Toxicology, Philadelphia College of Pharmacy and Science, PA 19104, USA.
Young
L H
LH
Voigt
J M
JM
D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D017403:In Situ Hybridization; D008321:Mammary Glands, Animal / Q000187:drug effects* / Q000378:metabolism; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000235:genetics*; D008770:Methylnitrosourea; D010052:Ovariectomy; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; D008770:Methylnitrosourea; D002117:Calcitriol