Decreased expression of early growth response-1 and its role in uterine leiomyoma growth.
Expression of early growth response (Egr)-1, a transcriptional factor implicated in growth regulation, is suppressed in several malignant tumors. The present study investigated the expression of Egr-1 and related genes in uterine leiomyoma and normal myometrium to determine possible contributions of Egr-1 to neoplastic growth in leiomyoma cells. Levels of Egr-1 transcripts were decreased in all leiomyomas (n = 20) to approximately 10% of levels in corresponding myometrium, where basal expression was high. Preoperative leuprorelin acetate therapy increased levels of Egr-1 mRNA in normal myometrium only. Northern blot analysis using additional sample sets (n = 5) revealed the full-length Egr-1 transcript. Western blot analysis (n = 5) confirmed decreased expression of Egr-1 protein. Southern blot analysis of the Egr-1 gene and microsatellite analysis of the chromosomal location at 5q31 (D5S414, D5S500, and D5S476) revealed neither DNA recombination nor loss of heterozygosity in leiomyomas. Moreover, Egr-1 retained identical responsiveness to phorbol 12-myristate 13-acetate in primary cultures derived from both leiomyoma and normal tissues. Electrophoretic mobility shift analysis revealed that phorbol 12-myristate 13-acetate-induced Egr-1 in leiomyoma cells retained DNA binding ability. Egr-1 thus appears functionally intact in leiomyoma cells. Finally, consistent with the role of Egr-1 in growth inhibition, transfection of Egr-1 expression vector into a myometrial cell line (KW) that expresses low levels of Egr-1 and displays rapid growth inhibited thymidine uptake in these cells. Egr-1 may display tumor-suppressing activity and offers a potential target for leiomyoma management.
Shozu
Makio
M
Department of Obstetrics and Gynecology, Kanazawa University School of Medicine, Kanazawa, Japan. shozu@med.kanazawa-u.ac.jp
Murakami
Kouichi
K
Segawa
Tomoya
T
Kasai
Tadayuki
T
Ishikawa
Hiroshi
H
Shinohara
Kazunori
K
Okada
Masahiko
M
Inoue
Masaki
M
D000328:Adult; D002455:Cell Division / Q000235:genetics; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015536:Down-Regulation; D051766:Early Growth Response Protein 1; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D025743:HMGA2 Protein / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D017874:Immediate-Early Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D007889:Leiomyoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D008875:Middle Aged; D009130:Muscle, Smooth / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014162:Transfection; D014594:Uterine Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D014599:Uterus / Q000378:metabolism
D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D025743:HMGA2 Protein; D017874:Immediate-Early Proteins; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D014157:Transcription Factors; D004247:DNA