This Article Full Text Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sumitani, H. Articles by Inoue, M. Search for Related Content PubMed PubMed Citation Articles by Sumitani, H. Articles by Inoue, M. Pubmed/NCBI databases Medline Plus Health Information Uterine Cancer Uterine Fibroids

In Situ Estrogen Synthesized by Aromatase P450 in Uterine Leiomyoma Cells Promotes Cell Growth Probably Via an Autocrine/Intracrine Mechanism¹

Department of Obstetrics and Gynecology, Kanazawa University School of Medicine, 13–1 Takaramachi, Kanazawa 920-0934, Japan

Address all correspondence and requests for reprints to: Makio Shozu, M.D., Ph.D., Department of Obstetrics and Gynecology, Kanazawa University School of Medicine, 13–1 Takaramachi, Kanazawa 920-0934, Japan. E-mail: shozu{at}med.kanazawa-u.ac.jp

In the present study we characterized in detail the expression of aromatase P450 in leiomyomas to determine the role of in situ estrogen in the growth advantage of leiomyomas. The levels of aromatase P450 transcripts were determined by quantitative RT-PCR to be significantly higher in leiomyomas than in corresponding myometrium. The overexpression of aromatase P450 in leiomyomas was also confirmed by Western blot analysis. The estimated size of immunoreactive aromatase was 58 kDa, similar to that in placenta. To identify a cell type that express aromatase P450 in leiomyomas, histological specimens were stained for aromatase P450 using a polyclonal antibody. Strong immunoreactivity was detected in the cytoplasm of leiomyoma cells, whereas surrounding normal myometrium displayed weak or negative staining. Smooth muscle-like cells in culture obtained from leiomyomas, positive for actin D fiber, possessed immunoreactive granules of aromatase in the cytoplasm. Conversion of androgen to estrogen was effectively stimulated by phorbol myristate acetate and dexamethasone plus interleukin-1ß and was completely abolished by selective inhibitors of aromatase P450 (fadrozole and TZA-2209), but not by inhibitors of 5-reductase (finasteride and flutamide). The apparent K_m of androstenedione was 3 nM in the presence of dexamethasone and interleukin-1ß, corresponding to the plasma concentration of androstenedione in women of reproductive age. To determine whether endogenous aromatase P450 plays a role in the growth promotion of leiomyoma cells, we evaluated the cell growth of smooth muscle-like cells treated with various concentrations of estrogen and androgen using a WST-1 assay. Treatment with testosterone (10^-8 and 10^-7 M) and androstenedione (10^-8 and 10^-7 M) stimulated the growth of smooth muscle-like cells obtained from leiomyomas to the same extent as estradiol (10^-10–10^-7 M), whereas dihydrotestosterone (10^-11–10^-8 M) did not. The stimulatory effect of testosterone on cell growth was again abolished by cotreatment with fadrozole. The level of estradiol in the medium of testosterone (10^-8 M)-treated smooth muscle-like cells was 10^-11 M, which was 1 order lower than the minimum concentration of estradiol necessary to promote cell growth (10^-10 M). This indicates that estradiol synthesized in leiomyomas promotes their growth via an autocrine/intracrine mechanism. We conclude that myometrial cells of leiomyomas overexpress aromatase P450 and are able to synthesize sufficient estrogen to accelerate their own cell growth. Overexpression of aromatase P450 may play a role in the growth advantage of leiomyoma tissue over surrounding myometrium via an autocrine/intracrine mechanism.

This article has been cited by other articles:

				H. Ishikawa, V. Fencki, E. E. Marsh, P. Yin, D. Chen, Y.-H. Cheng, S. Reisterd, Z. Lin, and S. E. Bulun CCAAT/Enhancer Binding Protein {beta} Regulates Aromatase Expression via Multiple and Novel Cis-Regulatory Sequences in Uterine Leiomyoma J. Clin. Endocrinol. Metab., March 1, 2008; 93(3): 981 - 991. [Abstract] [Full Text] [PDF]

				O. Bukulmez, D. B. Hardy, B. R. Carr, R. A. Word, and C. R. Mendelson Inflammatory Status Influences Aromatase and Steroid Receptor Expression in Endometriosis Endocrinology, March 1, 2008; 149(3): 1190 - 1204. [Abstract] [Full Text] [PDF]

				H. Ishikawa, M. Shozu, M. Okada, M. Inukai, B. Zhang, K. Kato, T. Kasai, and M. Inoue Early growth response gene-1 plays a pivotal role in down-regulation of a cohort of genes in uterine leiomyoma J. Mol. Endocrinol., November 1, 2007; 39(5): 333 - 341. [Abstract] [Full Text] [PDF]

				F. K. Varelas, A. N. Papanicolaou, N. Vavatsi-Christaki, G. A. Makedos, and G. D. Vlassis The Effect of Anastrazole on Symptomatic Uterine Leiomyomata Obstet. Gynecol., September 1, 2007; 110(3): 643 - 649. [Abstract] [Full Text] [PDF]

				A. G. Imir, Z. Lin, P. Yin, S. Deb, B. Yilmaz, M. Cetin, A. Cetin, and S. E. Bulun Aromatase Expression in Uterine Leiomyomata Is Regulated Primarily by Proximal Promoters I.3/II J. Clin. Endocrinol. Metab., May 1, 2007; 92(5): 1979 - 1982. [Abstract] [Full Text] [PDF]

				S. E. Bulun, Z. Lin, G. Imir, S. Amin, M. Demura, B. Yilmaz, R. Martin, H. Utsunomiya, S. Thung, B. Gurates, et al. Regulation of Aromatase Expression in Estrogen-Responsive Breast and Uterine Disease: From Bench to Treatment Pharmacol. Rev., September 1, 2005; 57(3): 359 - 383. [Abstract] [Full Text] [PDF]

				T. Segawa, M. Shozu, K. Murakami, T. Kasai, K. Shinohara, K. Nomura, S. Ohno, and M. Inoue Aromatase Expression in Stromal Cells of Endometrioid Endometrial Cancer Correlates with Poor Survival Clin. Cancer Res., March 15, 2005; 11(6): 2188 - 2194. [Abstract] [Full Text] [PDF]

				T. Kasai, M. Shozu, K. Murakami, T. Segawa, K. Shinohara, K. Nomura, and M. Inoue Increased Expression of Type I 17{beta}-Hydroxysteroid Dehydrogenase Enhances in Situ Production of Estradiol in Uterine Leiomyoma J. Clin. Endocrinol. Metab., November 1, 2004; 89(11): 5661 - 5668. [Abstract] [Full Text] [PDF]

				J. A. Rivera, S. Christopoulos, D. Small, and M. Trifiro Hormonal Manipulation of Benign Metastasizing Leiomyomas: Report of Two Cases and Review of the Literature J. Clin. Endocrinol. Metab., July 1, 2004; 89(7): 3183 - 3188. [Abstract] [Full Text] [PDF]

				M. Shozu, K. Murakami, T. Segawa, T. Kasai, H. Ishikawa, K. Shinohara, M. Okada, and M. Inoue Decreased Expression of Early Growth Response-1 and Its Role in Uterine Leiomyoma Growth Cancer Res., July 1, 2004; 64(13): 4677 - 4684. [Abstract] [Full Text] [PDF]

				H.-J. Yang, M. Shozu, K. Murakami, H. Sumitani, T. Segawa, T. Kasai, and M. Inoue Spatially Heterogenous Expression of Aromatase P450 through Promoter II Is Closely Correlated with the Level of Steroidogenic Factor-1 Transcript in Endometrioma Tissues J. Clin. Endocrinol. Metab., August 1, 2002; 87(8): 3745 - 3753. [Abstract] [Full Text] [PDF]

				M. Shozu, H. Sumitani, T. Segawa, H.-J. Yang, K. Murakami, T. Kasai, and M. Inoue Overexpression of Aromatase P450 in Leiomyoma Tissue Is Driven Primarily through Promoter I.4 of the Aromatase P450 Gene (CYP19) J. Clin. Endocrinol. Metab., June 1, 2002; 87(6): 2540 - 2548. [Abstract] [Full Text] [PDF]

				O. Khorram, M. Garthwaite, and T. Golos Uterine and ovarian aryl hydrocarbon receptor (AHR) and aryl hydrocarbon receptor nuclear translocator (ARNT) mRNA expression in benign and malignant gynaecological conditions Mol. Hum. Reprod., January 1, 2002; 8(1): 75 - 80. [Abstract] [Full Text] [PDF]

				M. Shozu, H. Sumitani, T. Segawa, H.-J. Yang, K. Murakami, and M. Inoue Inhibition of in Situ Expression of Aromatase P450 in Leiomyoma of the Uterus by Leuprorelin Acetate J. Clin. Endocrinol. Metab., November 1, 2001; 86(11): 5405 - 5411. [Abstract] [Full Text] [PDF]