ABSTRACT
Renal cell carcinoma is an important clinical disease with poorly understood etiology. ELF5 is an epithelial-specific member of the Ets family of transcription factors, characterized by the 80 amino acid Ets domain that binds the purine-rich GGAA/T Ets motif found in the promoter regions of a variety of genes. Since ELF5 is highly expressed in kidney and has been postulated to function as a tumor suppressor, at least in the context of the breast, we investigated its role in kidney cancer. In renal cell carcinoma ELF5 expression was consistently decreased in tumor samples versus normal. ELF5 mRNA was decreased in 94% of lesions tested and ELF5 protein was undetectable in 40/40 kidney-derived carcinomas. Re-expression of the ELF5 gene in 786-O renal carcinoma cells suppressed their tumorigenic capacity in vitro and in vivo. This work is the first to suggest that ELF5 has tumor suppressor activity in the kidney.
Subject(s)
Carcinoma, Renal Cell/metabolism , Genes, Tumor Suppressor , Kidney Neoplasms/metabolism , Kidney/metabolism , Proto-Oncogene Proteins c-ets/metabolism , Animals , Blotting, Western , Carcinoma, Renal Cell/genetics , Carcinoma, Renal Cell/pathology , DNA-Binding Proteins , Female , Humans , Immunoenzyme Techniques , Kidney Neoplasms/genetics , Mice , Mice, SCID , Proto-Oncogene Proteins c-ets/genetics , RNA, Messenger/genetics , Reverse Transcriptase Polymerase Chain Reaction , Transcription Factors , Tumor Cells, CulturedABSTRACT
Elf5 is an epithelial-specific ETS factor. Embryos with a null mutation in the Elf5 gene died before embryonic day 7.5, indicating that Elf5 is essential during mouse embryogenesis. Elf5 is also required for proliferation and differentiation of mouse mammary alveolar epithelial cells during pregnancy and lactation. The loss of one functional allele led to complete developmental arrest of the mammary gland in pregnant Elf5 heterozygous mice. A quantitative mRNA expression study and Western blot analysis revealed that decreased expression of Elf5 correlated with the downregulation of milk proteins in Elf5(+/-) mammary glands. Mammary gland transplants into Rag(-/-) mice demonstrated that Elf5(+/-) mammary alveolar buds failed to develop in an Elf5(+/+) mammary fat pad during pregnancy, demonstrating an epithelial cell autonomous defect. Elf5 expression was reduced in Prolactin receptor (Prlr) heterozygous mammary glands, which phenocopy Elf5(+/-) glands, suggesting that Elf5 and Prlr are in the same pathway. Our data demonstrate that Elf5 is essential for developmental processes in the embryo and in the mammary gland during pregnancy.
Subject(s)
Fetal Development/physiology , Mammary Glands, Animal/growth & development , Transcription Factors/physiology , Animals , Base Sequence , DNA/genetics , Epithelial Cells/pathology , Female , Fetal Development/genetics , Gene Expression Regulation, Developmental , Heterozygote , Lactation , Mammary Glands, Animal/pathology , Mice , Mice, Knockout , Pregnancy , RNA, Messenger/genetics , RNA, Messenger/metabolism , Receptors, Prolactin/genetics , Receptors, Prolactin/metabolism , Transcription Factors/deficiency , Transcription Factors/geneticsABSTRACT
Elf5 belongs to the ets family of transcription factors and was cloned by homology in the DNA binding domain to the related, epithelial-specific ets factor, Elf3. Elf5 mRNA is expressed highly in normal tissue rich in secretory epithelial cells, including mammary gland, lung, kidney, prostate, salivary gland and stomach. The function of Elf5 and the cell types in which it is expressed remain uncharacterised. The presence of Elf5 mRNA in normal tissues, but absence in cancer tissues, may suggest a role for Elf5 in differentiation and development. We have generated a rabbit antiserum directed against a peptide in the Elf5 DNA-binding domain that is conserved between murine and human sequences. The antiserum specifically detects human and murine Elf5 proteins on western blots and shows specific staining on paraffin-embedded sections obtained from tissues including mammary gland, kidney, salivary gland and stomach. Epithelia from the bladder lining, lung and prostate did not stain for the presence of Elf5, though these organs express Elf5 mRNA. We show for the first time that Elf5 is primarily expressed in epithelial cells and is likely to be an epithelial-specific protein. The antiserum should prove useful in further analysis of the expression and function of Elf5.
