help button home button Endocrine Society JCEM JCEM Call for Nominations for EIC
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Submit a related Letter to the Editor
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Gao, Z.
Right arrow Articles by Maruo, T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Gao, Z.
Right arrow Articles by Maruo, T.
Right arrowPubmed/NCBI databases
*Compound via MeSH
*Substance via MeSH
Hazardous Substances DB
*ESTRADIOL
*PROGESTERONE
Medline Plus Health Information
*Uterine Cancer
*Uterine Fibroids
The Journal of Clinical Endocrinology & Metabolism Vol. 87, No. 8 3915-3920
Copyright © 2002 by The Endocrine Society

Original Article

p53 Tumor Suppressor Protein Content in Human Uterine Leiomyomas and Its Down-Regulation by 17ß-Estradiol

Zhijian Gao, Hiroya Matsuo, Satoshi Nakago, Osamu Kurachi and Takeshi Maruo

Department of Obstetrics and Gynecology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan

Address all correspondence and requests for reprints to: Takeshi Maruo, M.D., Department of Obstetrics and Gynecology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan. E-mail: . maruo{at}kobe-u.ac.jp

Abstract

p53 protein, a tumor suppressor gene product, has been reported to play a crucial role in suppressing the growth of a variety of cancer cells. However, little information is currently available regarding the content of p53 protein in human leiomyomas. The present study was conducted to elucidate the p53 protein content in human leiomyomas and its regulation by sex steroid hormones. The content of p53 protein in leiomyomas was examined by immunohistochemical staining and Western blot analysis in comparison with that in the adjacent normal myometrium or leiomyoma specimens from GnRH agonist-treated patients. In addition, isolated human leiomyoma cells were subcultured in phenol red-free DMEM supplemented with 10% FBS for 120 h and then stepped down to serum-free conditions for an additional 72 h in the absence or presence of 17ß-estradiol (E2; 10 ng/ml), progesterone (P4; 100 ng/ml), or E2 (10 ng/ml) plus P4 (100 ng/ml). The effects of sex steroids on p53 protein content in cultured leiomyoma cells were also assessed by Western immunoblot analysis. Immunohistochemical staining and Western blot analysis revealed that p53 protein content was highest in leiomyomas treated with GnRH agonist for 16 wk, lower in leiomyomas in the secretory, P4-dominated phase, and lowest in leiomyomas in the proliferative, E2-dominated phase of the menstrual cycle. There was no difference in p53 content between leiomyomas and the adjacent normal myometrium. Western blot analysis of cultured leiomyoma cell extracts revealed that E2 treatment significantly decreased p53 protein content compared with the control cultures, whereas either P4 treatment or combined treatment with E2 and P4 did not affect p53 protein content in cultured leiomyoma cells. The concentrations of sex steroid hormones used were within the physiological tissue concentrations in leiomyomas and myometrium described earlier. The present study suggests that E2 down-regulates p53 protein content, whereas P4 is ineffective in those cells. The E2-induced decrease in p53 protein content in leiomyoma cells leads us to propose that E2 may regulate human leiomyoma growth in part by down-regulating p53 tumor suppressor protein content in those cells.

THE GROWTH OF uterine leiomyoma is regulated by ovarian sex steroid hormones (1, 2) mediated in part by local growth factors such as IGF-I (3) and epidermal growth factor (4). It grows during the reproductive years and regresses after menopause (1, 2). Furthermore, treatment with GnRH agonist, which reduces ovarian steroid hormone concentrations, leads to a reduction in the size of leiomyomas; however, regrowth of leiomyomas occurs after therapy with GnRH agonist is discontinued (5). These observations suggest that ovarian sex steroid hormones play a vital role in regulating the growth of human leiomyomas.

The progression of the neoplastic state is influenced by deregulation of oncogenes or inactivation of tumor suppressors (6). Our previous studies have demonstrated the increased expression of Bcl-2 protein, an apoptosis-inhibiting gene product, in uterine leiomyoma relative to the adjacent normal myometrium in the same individual uterus and its up-regulation by progesterone (P4) in cultured leiomyoma cells (7). We have also noted that treatment with either P4 or 17ß-estradiol (E2) increased proliferating cell nuclear antigen expression in cultured leiomyoma cells (8). Although sex steroid hormones have been shown to regulate protooncogenes (7, 9), little is known concerning the effects of sex steroids on p53 protein in uterine leiomyoma cells. Thus, in the present study we investigated how sex steroids regulate p53 protein content in uterine leiomyoma cells, and how an agent used in the medical treatment of leiomyomas, such as GnRH agonist, affects the content of p53 protein in human leiomyomas.

p53 gene is a tumor suppressor gene located on chromosome 17p. The wild-type p53 protein encoded by the p53 tumor suppressor gene is a nuclear phosphoprotein and is capable of suppressing the growth of a variety of cancer cells (10, 11, 12, 13). It is now widely recognized that p53 may be the most frequently mutated protein in human cancer, implying that an alteration of p53 is a fundamentally important step in genomic instability and susceptibility to neoplastic state transformation (14, 15). p53 functions as a transcription factor directly regulating the expression of factors such as p21, GADD45, or Bax, which are involved in the control of cell cycle (16) and programmed cell death (17, 18, 19). It binds to damaged DNA, repairs it, and induces cell cycle arrest at G1 phase or apoptosis (20). The loss of p53 may contribute to tumor progression by arresting the cells in a relatively immature state (14). Therefore, p53 has been categorized as both a caretaker and gatekeeper tumor suppressor gene (21). Because the biological activity of the p53 protein is associated with suppression of tumor cell growth, we explored the possible roles of E2 and P4 in regulating p53 protein content in cultured leiomyoma cells. p53 protein content was also examined in leiomyoma specimens from GnRH agonist-treated patients. The present study suggests that E2 down-regulates p53 protein content in leiomyoma cells, but P4 does not.

Materials and Methods

Materials

Phenol red-free DMEM and antibiotic solution (1 x 105 U/liter penicillin and 50 mg/liter streptomycin) were purchased from Life Technologies, Inc. (Grand Island, NY). E2 and P4 were obtained from Sigma (St. Louis, MO). Collagenase was purchased from Wako Pure Biochemical Industry (Osaka, Japan). A mouse monoclonal antibody to human p53 protein was purchased from Novacastra Laboratories Ltd. (Newcastle, UK), and a mouse antihuman ß- actin polyclonal antibody was obtained from Santa Cruz Biotechnology, Inc. (Santa Cruz, CA). The 10-cm2 culture dishes were purchased from Iwaki Glass Corp. (Chiba, Japan).

Tissue collection

Nineteen uterine leiomyomas and the adjacent normal myometrial tissues were collected from different patients with regular menstrual cycles, of which 10 were from the proliferative phase and 9 were from the secretory phase of the menstrual cycle. Twenty-one uterine leiomyoma tissues were obtained from different patients treated with GnRH agonist for various times [2 wk (n = 3), 4 wk (n = 4), 8 wk (n = 4), 12 wk (n = 4), and 16 wk (n = 6)]. The patients untreated with GnRH agonist did not receive any hormonal therapy for at least 6 menstrual cycles before surgery. The patients ranged in age from 30–42 yr and underwent abdominal hysterectomy or myomectomy for medically indicated reasons at Kobe University Hospital. Informed consent was obtained from each patient before surgery for the use of uterine tissues for the present study. The institutional review board approved the use of uterine tissues for culture experiments. Histological diagnosis of each uterine specimen was determined by a pathologist. Samples were excluded from the study if accurate menstrual cycle dates could not be assigned or if unexpected pathology (e.g. adenomyosis or leiomyosarcoma) was found.

Immunohistochemical staining for p53 protein

Uterine tissue specimens obtained were fixed in 4% buffered neutral formaldehyde solution, dehydrated, and embedded in paraffin. Sections, 5–6 µm thick, were deparaffinized and followed by standard histological techniques. The avidin/biotin immunoperoxidase staining method was performed with the use of a polyvalent immunoperoxidase kit (Omnitags, Lipshow, MI). An enhancement method (22) based on microwave oven heating of tissue sections was used for antigen retrieval. A mouse monoclonal antibody to human p53 protein was used at a dilution of 1:200 as the primary antibody in this study. To assure the specificity of the immunological reaction, control sections were subjected to the same immunoperoxidase method, except that the primary antibody was replaced by nonimmune murine IgG (Miles, Elkhart, IN) at the same dilution as the specific primary antibody.

Cell culture

Uterine leiomyoma tissues dissected from endometrial cell layers were cut into small pieces and digested in 0.2% collagenase (wt/vol) at 37 C for 3–5 h as previously described (3, 7). The leiomyoma cells were collected by centrifugation at 460 x g for 5 min and washed three times with DMEM containing 1% antibiotic solution. Cell viability was determined by trypan blue exclusion test. The isolated leiomyoma cells were plated at density of approximately 106 cells/dish in 10-cm2 culture dishes and then subcultured for 120 h at 37 C in a humidified atmosphere of 5% CO2-95% air in phenol red-free DMEM supplemented with 10% FBS (vol/vol; Life Technologies, Inc., Grand Island, NY). The monolayer cultures at approximately 60% confluence were treated with E2 (10 ng/ml), P4 (100 ng/ml), or E2 (10 ng/ml) plus P4 (100 ng/ml) in serum-free, phenol red-free DMEM for an additional 72 h. The control cultures were grown in phenol red-free DMEM without hormone treatment.

Protein extraction and Western immunoblotting

Leiomyomas and the adjacent normal myometrial tissues for protein extraction were collected immediately after hysterectomy or myomectomy. These tissue samples were homogenized at 4 C in the presence of lysis buffer (5 g tissue in 1–2 ml). Homogenates were subsequently centrifuged at 13,000 x g for 30 min, and the supernatants were collected. Proteins were also extracted from cultured cells as described previously (3). At the termination of culture, cultured cells were lysed at 4 C for 20 min in the lysis buffer (150 mM NaCl, 2 mM phenylmethylsulfonylfluoride, 1% Nonidet P-40, 0.5% deoxycholate, 1 mg/liter aprotinin, 0.1% sodium dodecyl sulfate, and 50 mM Tris-HCl, pH 7.5). The lysates were subsequently centrifuged at 13,000 x g for 30 min at 4 C, and the supernatants were collected. Protein content in the supernatants was determined by the Bradford assay (23) with BSA as a standard.

Each 80-µg aliquot of proteins extracted from cultured cells and uterine tissues was separated by 10% SDS-PAGE under reducing conditions using 20–25 mA for the stacking gel and 30–35 mA for the separating gel for 2–3 h. The proteins were then electrophoretically transferred from gels to nitrocellulose membranes (Bio-Rad Laboratories, Inc., Hercules, CA). Blots were exposed overnight to the monoclonal antibody to p53 protein at a dilution of 1:500 in blocking buffer. The membranes were incubated for 1 h with horseradish peroxidase-conjugated goat antimouse secondary antibody (Amersham Pharmacia Biotech, Arlington Heights, IL) that was diluted 1:2000 with blocking buffer. The antigen-antibody complexes were detected with the enhanced chemiluminescence detection kit (ECL, Amersham Pharmacia Biotech). Membranes were visualized by exposure to X-OMAT film (Eastman Kodak Co., Rochester, NY). The radioautograms were then scanned and quantified with ChemiImager 4400 (Astec Co. Ltd., Osaka, Japan). After detection of the p53 protein under investigation, blots were stripped and, as a loading control, probed with an antibody to ß-actin, followed by the procedures described above.

Data analysis

The data were expressed as the mean ± SD. Statistical analysis was performed using ANOVA with StatView 4.1 software (SAS Institute, Inc., Cary, NC) for Macintosh, followed by post hoc testing using Dunnett’s test or Fisher’s protected least significant difference test where appropriate. Differences with a P value less than 0.05 were considered statistically significant.

Results

Immunohistochemical examination showed that p53 protein was immunolocalized to the nuclei of leiomyoma cells. The p53 protein content in leiomyoma cells was higher in the secretory, P4-dominated phase (Fig. 1BGo) than that in the proliferative phase of the menstrual cycle (Fig. 1AGo). The p53 protein content was highest in the leiomyoma receiving GnRH agonist therapy for 16 wk (Fig. 1CGo). Replacement of the specific primary antibody with nonimmune murine IgG resulted in a lack of positive immunostaining in the leiomyoma cell nuclei (Fig. 1DGo).



View larger version (109K):
[in this window]
[in a new window]
  		Figure 1. Immunohistochemical staining for p53 in formalin-fixed paraffin-embedded sections of leiomyoma tissues in the proliferative phase (A), the secretory phase of the menstrual cycle (B), and leiomyoma tissues from patients treated with GnRH agonist for 16 wk (C). p53 protein was immunolocalized to the nuclei of leiomyoma cells. p53 protein content was highest in leiomyoma treated with GnRH agonist therapy for 16 wk (C), lower in leiomyomas in the secretory, P4-dominated phase (B), and lowest in the proliferative, E2-dominated phase of the menstrual cycle (A). Replacement of the primary antibody with nonimmune murine IgG resulted in a lack of positive immunostaining in the leiomyoma cell nuclei (D). Bars, 5 µm; original magnification, x400.

 
Western immunoblot analysis revealed that the p53 protein content in leiomyomas in the secretory phase was higher than that in the proliferative phase of the menstrual cycle. There were no apparent differences in the p53 protein content between leiomyoma tissues and the adjacent myometrial tissues. The p53 protein content was significantly increased in leiomyoma tissues during GnRH agonist therapy for 12 or 16 wk compared with that in untreated leiomyoma tissues (Fig. 2Go, A and C). A lower band that cross-reacted with the antibody to human p53 protein was also observed in the leiomyoma tissues under GnRH agonist therapy for 16 wk. This extra protein band might be an unspecific immuno reactive band. As shown in Fig. 2BGo, justification for protein loading efficiency was achieved by detecting ß-actin levels in the corresponding samples.



View larger version (24K):
[in this window]
[in a new window]
  		Figure 2. Western immunoblot analysis with a monoclonal antibody of p53 protein content of leiomyoma and the adjacent normal myometrial tissues as well as leiomyoma tissues treated with GnRH agonist for 12 or 16 wk. A, The p53 protein content in leiomyomas was higher in the secretory phase (S) than in the proliferative phase (P) of the menstrual cycle. There were no apparent differences in p53 protein content between leiomyoma tissues and the adjacent normal myometrial tissues. The p53 protein content was significantly increased in leiomyoma tissues treated with GnRH agonist for 12 or 16 wk compared with that in untreated leiomyoma tissues. B, ß-Actin as a loading control. C, Relative content assessed by densitometric analysis refers to the ratio of p53 content observed relative to that in leiomyomas in the proliferative phase. *, P < 0.05 vs. p53 content in untreated leiomyoma tissues in the proliferative phase of the menstrual cycle.

 
Western immunoblot analysis of proteins extracted from leiomyoma cells cultured for 72 h under serum-free conditions in the presence or absence of sex steroid hormones (E2, 10 ng/ml; P4, 100 ng/ml; E2 10 ng/ml plus P4, 100 ng/ml) revealed that cultured leiomyoma cells contained immunoreactive p53 protein. The p53 protein content was significantly decreased in cultured leiomyoma cells treated with E2 (10 ng/ml) compared with that in untreated cells in control cultures, whereas either treatment with P4 (100 ng/ml) or combined treatment with E2 (10 ng/ml) and P4 (100 ng/ml) showed no apparent change in p53 protein content in cultured leiomyoma cells (Fig. 3Go, A and C). Figure 3BGo shows ß-actin levels in the corresponding samples.



View larger version (25K):
[in this window]
[in a new window]
  		Figure 3. Effects of E2 and P4 on p53 protein content in cultured leiomyoma cells as assessed by Western immunoblot analysis. Isolated leiomyoma cells were cultured for 72 h under serum-free conditions in the absence or presence of sex steroid hormones (E2, 10 ng/ml; P4, 100 ng/ml; E2, 10 ng/ml, plus P4, 100 ng/ml). Each 80-µg aliquot of proteins extracted from cultured leiomyoma cells was subjected to Western immunoblotting with a monoclonal antibody to p53. A, The p53 protein content was decreased in leiomyoma cells treated with E2 (10 ng/ml) compared with that in untreated cells in control cultures, whereas treatment with either P4 (100 ng/ml) or E2 (10 ng/ml) plus P4 (100 ng/ml) showed no apparent effect on p53 protein content in cultured leiomyoma cells. B, ß-Actin as a loading control. C, Relative content assessed by densitometric analysis refers to the ratio of p53 content observed relative to that in control cultures. *, P < 0.05 vs. p53 content in leiomyoma cells in untreated control cultures.

 
Discussion

The wild-type protein product of the tumor suppressor gene, p53, is a nuclear phosphoprotein, which functions as a transcription factor directly regulating the expression of factors involved in cell cycle control (16) and programmed cell death (17, 18, 19). The occupancy of response elements by p53 and its ability to trans-activate responsive genes would at least partially depend on its intranuclear concentration (24). Because uterine leiomyoma is considered to be a sex steroid-dependent tumor, we evaluated the effects of sex steroid hormones on p53 protein content in uterine leiomyoma cells using immunohistochemical staining and Western blot analysis.

The present study demonstrates for the first time that p53 protein content in leiomyoma cells is down-regulated by E2. As p53 is a tumor suppressor gene that directly regulates the growth of tumors by inhibiting tumor cell growth or promoting cell death (16, 17, 18, 19), we propose that E2 may stimulate in part leiomyoma growth by decreasing the p53 protein levels in the nuclei and suppressing normal p53 functions. Using Western blot analysis and immunohistochemical staining, Molinari et al. (25) also demonstrated that estrogen-induced p53 inactivation by nuclear exclusion is involved in estrogen-induced cell proliferation of MCF-7, a hormone-dependent breast cancer cell line. Their findings are, to some extent, in agreement with our results obtained with uterine leiomyoma cells.

In contrast, in the present study treatment with P4 alone or with E2 plus P4 did not affect p53 protein content in cultured leiomyoma cells. This observation may suggest that P4 has no effect on p53 protein content or that P4 blocks or inverses the effect of E2 on p53 protein content in leiomyoma cells. The former possibility is in agreement with a similar observation with another hormone-dependent tumor, T47D human breast carcinoma cells, in which progesterone does not influence p53 protein levels (24). Several studies have demonstrated that P4 can block or reverse some effects of E2. Gompel et al. (26) reported that the proliferation of normal breast epithelial cells stimulated by 0.01 µM E2 is blocked more than 90% by 0.1 µM P4. In the endometrium elevated E2 levels increase cancer risk, whereas P4 counteracts the E2-induced cancer risk (27, 28). There is, however, no report indicating that P4 blocks or reverses the effect of E2 on p53 content in other tumor cells. This study is believed to be the first to report the possibility that P4 may block or reverse the effect of E2 on p53 content in leiomyoma cells. The link between sex steroid hormones and p53 protein content in leiomyomas has remained unknown and awaits further investigation.

GnRH agonist therapy is a popular and effective treatment for human uterine leiomyomas. The molecular events necessary for GnRH agonist-induced reduction in the size of uterine leiomyomas are not well understood, however. The present study demonstrates that p53 protein content is significantly increased in leiomyoma tissues during GnRH agonist therapy for 12 or 16 wk compared with that in the untreated leiomyoma tissues. As the biological activity of the tumor suppressor p53 protein is associated with suppression of tumor cell growth, intracellular levels of p53 protein remarkably increase in response to a variety of DNA-damaging tumor agents (29, 30, 31, 32). Functional p53 binds and activates p53-responsive genes such as p21, GADD45, and bax (16, 17, 18, 19); arrests cell cycles at the G1 phase; or targets the damaged cell for apoptosis when it is overexpressed (15). Therefore, the present finding that the p53 protein content is significantly increased during GnRH agonist therapy may explain one of the molecular bases for GnRH agonist-induced reduction in the size of uterine leiomyomas.

The present study also demonstrates that there are no apparent differences in p53 protein content between leiomyoma tissues and its adjacent normal myometrial tissues. A similar observation was reported in another sex steroid- dependent tumor, uterine endometrioid carcinoma, in which there were no changes in p53 level between endometrioid carcinoma and the adjacent tissue (33).

Of note, because p53 protein may be highly unstable in the majority of human cancer (14, 15), the alterations in p53 protein content observed in the present study might be determined not only by p53 protein expression, but also its degradation in leiomyoma cells. p53 degradation is commonly controlled by the ubiquitin-proteosome pathway (UPP), which is the major system for the rapid degradation of some regulatory proteins in the eukaryotic cells (34). Although there is no apparent evidence suggesting that the UPP-dependent degradation is involved in the alterations in p53 protein content in the present study, many studies have demonstrated that p53 protein is degraded and controlled through the UPP in other cell types (35, 36). If p53 is normal, it guards the genome against somatic mutations that may initiate cancer (10, 11, 12, 13); however, if p53 is inactivated, it is unable to prevent increased genetic instability and lacks antioncogenic function (37, 38). Furthermore, Kenneth et al. (39) reported that once a tumor is initiated by inactivation of a gatekeeper gene, it may progress rapidly due to an accelerated rate of mutation in other genes that directly control cell growth or death. In this context, the further studies will be needed to investigate the role of the UPP in p53 protein inactivation in leiomyoma cells.

In conclusion, we have demonstrated that p53 tumor suppressor content was remarkably increased in leiomyomas treated with GnRH agonist for 16 wk, lower in leiomyomas in the secretory, P4-dominated phase and lowest in leiomyomas in the proliferative, E2-dominated phase of the menstrual cycle. Consistent with these in vivo findings, the p53 protein content in leiomyoma cells cultured under serum-free, phenol red-free conditions was decreased by E2, but was not affected by P4 or E2 plus P4.

Acknowledgments

Footnotes

This work was supported in part by Grand-in-Aid for Scientific Research 10470346 from the Japanese Ministry of Education, Science, and Culture, the International Committee of The Population Council (New York, NY), and the Ogyaa-Donation Foundation of Japan Association of Obstetricians and Gynecologists.

Abbreviations: E2, 17ß-Estradiol; P4, progesterone; UPP, ubiquitin-proteosome pathway.

Received January 25, 2002.

Accepted April 17, 2002.

References

  1. Rein MS, Nowak RA 1992 Biology of uterine myomas and myometrium in vitro. In: Barbieri RL, ed. Seminars in productive endocrinology. New York: Thieme; 310–319
  2. Cramer SF, Marchetti C, Freedman J, Padela A 2000 Relationship of myoma cell size and menopausal status in small uterine leiomyomas. Arch Pathol Lab Med 124:1448–1453[Medline]
  3. Gao Z, Matsuo H, Wang Y, Nakago S, Maruo T 2001 Up-regulation by IGF-I of proliferating cell nuclear antigen and Bcl-2 protein expression in human uterine leiomyoma cells. J Clin Endocrinol Metab 86:5593–5599[Abstract/Free Full Text]
  4. Huet-Hudson YM, Chakraborty C, Suzaki Y, Andrews GK, Dey SK 1990 Estrogen regulates synthesis of epidermal growth factor in mouse uterine epithelial cells. Mol Endocrinol 4:510–523[Abstract]
  5. Friedman AJ, Lobel SM, Rein MS, Barbiert RL 1990 Efficacy and safety considerations in women with uterine leiomyomas treated with GnRHas: the estrogen threshold hypothesis. Am J Obstet Gynecol 163:1114–1119[Medline]
  6. Hurd C, Khattree N, Alban P, Moudgil VK 1997 Regulation of tumor suppressor proteins, p53 and retinoblastoma, by estrogen and antiestrogens in breast cancer cells. Oncogene 15:991–995[CrossRef][Medline]
  7. Matsuo H, Maruo T, Samoto T 1997 Increased expression of Bcl-2 protein in human uterine leiomyoma and its up-regulation by progesterone. J Clin Endocrinol Metab 82:293–299[Abstract/Free Full Text]
  8. Shimomura Y, Matsuo H, Samoto T, Maruo T 1998 Up-regulation by progesterone of proliferating cell nuclear antigen and epidermal growth factor expression in human uterine leiomyoma. J Clin Endocrinol Metab 83:2192–2198[Abstract/Free Full Text]
  9. Schuchard M, Landers JP, Sandhu NP, Spelsberg TC 1993 Steroid hormone regulation of nuclear proto-oncogenes. Endocr Rev 14:659–669[Abstract]
  10. Finlay CA, Hinds PW, Levine AJ 1989 The p53 proto-oncogene can act as a suppressor of transformation. Cell 57:1083–1093[CrossRef][Medline]
  11. Malkin D, Li FP, Strong LC, Fraumeni JF, Nelson CE, Kim DH, Kassel J, Gryka MA, Bischoff FZ, Tainsky MA, Friend SH 1990 Germ line p53 mutations in a familial syndrome of breast cancer, sarcomas, and other neoplasms. Science 250:1233–1238[Abstract/Free Full Text]
  12. Chen PL, Chen YM, Bookstein R, Lee WH 1990 Genetic mechanisms of tumor suppression by human p53 gene. Science 250:1576–1580[Abstract/Free Full Text]
  13. Yin Y, Tainsky MA, Bischoff FZ, Strong LC, Wahl GW 1992 Wide-type p53 restores cell cycle control and inhibits gene amplification in cells with mutant p53 alleles. Cell 70:937–948[CrossRef][Medline]
  14. Oren M 1992 p53: the ultimate tumor suppressor gene? FASEB J 6:3169–3176[Abstract]
  15. Jung MS, Yun J, Chae HD, Kim JM, Kim SC, Choi TS, Shin DY 2001 p53 and its homologues, p63 and p73, induce a replicative senescence through inactivation of NF-Y transcription factor. Oncogene 20:5818–5825[CrossRef][Medline]
  16. Kastan MB, Zhan Q, EL-Deiry WS, Carrier F, Jacks T, Walsh WV, Plunkett BS, Vogelstein B, Fornace AJ 1992 A mammalian cell cycle checkpoint pathway utilizing p53 and GADD45 is defective in ataxia-telangiectasia. Cell 71:587–597[CrossRef][Medline]
  17. Miyashita T, Reed J 1995 Tumor suppressor p53 is a direct transcriptional activator of the human bax gene. Cell 80:293–299[CrossRef][Medline]
  18. Miyashita T, Harigai M, Hanada M, Reed J 1994 Identification of a p53-dependendent negative response element in the bcl-2 gene. Cancer Res 54:3131–3135[Abstract/Free Full Text]
  19. Oltvai ZN, Milliman CL, Korsmeyer SJ 1993 Bcl-2 heterodimerizes in vivo with a conserved homolog, bax, that accelerates programmed cell death. Cell 74:609–619[CrossRef][Medline]
  20. Lee JM, Berstein A 1993 p53 mutations increase resistance to ionizing radiation. Proc Natl Acad Sci USA 90:5742–5746[Abstract/Free Full Text]
  21. Lane DP 1992 p53, guardian of the genome. Nature 358:15–16[CrossRef][Medline]
  22. Shi SR, Key ME, Kalra KL 1991 Antigen retrieval in formalin-fixed, paraffin-embedded tissues: an enhancement method for immunohistochemical staining based on microwave oven heating of tissue sections. J Histochem Cytochem 6:741–748
  23. Bradford MM 1976 A rapid and sensitive method for the quantitation of microgram quantities of proteins utilizing the principle of protein-dye binding. Anal Biochem 72:248–253[CrossRef][Medline]
  24. Hurd C, Khattree N, Alban P, Nay K, Jhanwar SC, Dinda S, Moudgil VK 1995 Hormonal regulation of the p53 tumor suppressor protein in T47D human breast carcinoma cell line. J Biol Chem 270:28507–28510[Abstract/Free Full Text]
  25. Molinari AM, Bontempo P, Schiavone EM, Tortora V, Verdicchio MA, Napolitano M, Nola E, Moncharmont B, Medici N, Nigro V, Armetta I, Abbondanza C, Puca GA 2000 Estradiol induces functional inactivation of p53 by intracellular redistribution. Cancer Res 60:2594–2597[Abstract/Free Full Text]
  26. Gompel A, Malet C, Sprotzer P, Lalardrie JP, Knttenn F, Mauvais-Jarvis P 1986 Progestin effect on cell proliferation and 17ß-hydroxysteroid dehydrogenase activity in normal human breast cells in culture. J Clin Endocrinol Metab 63:1174–1180[Abstract]
  27. Henderson BE 1989 The cancer question: an overview of recent epidemiologic and retrospective data. Am J Obstet Gynecol 161:1859–1864[Medline]
  28. Hammond CB 1989 Estrogen replacement therapy: what the future holds. Am J Obstet Gynecol 161:1864–1868[Medline]
  29. Hall PA, Mckee PH, Menage HD, Dover R, Lane DP 1992 High level of p53 protein in UV irradiated human skin. Oncogene 90:574–583
  30. Kastan MB, Onyekwere O, Sidransky D, Vogelstein B, Craig RW 1991 Participation of p53 protein in the cellular response to DNA damage. Cancer Res 51:6304–6311[Medline]
  31. Lu X, Park SH, Thompson TC, Lane DP 1992 ras-induced hyperplasia occurs with mutation of p53, but an activated ras and myc together can induce carcinoma without p53 mutation. Cell 70:153–161[CrossRef][Medline]
  32. Maitzman W, Czyzk L 1984 UV irradiation stimulates levels of p53 cellular tumor antigen in nontransformed mouse cells. Mol Cell Biol 4:1689–1694[Abstract/Free Full Text]
  33. Li SF, Shiozawa T, Nakayama X, Fujii S 1996 Stepwise abnormality of sex steroid hormone receptors, tumor suppressor gene products (p53 and Rb), and cyclin E in uterine endometrioid carcinoma. Cancer 17:321–329
  34. Ciechanover A 1994 The ubiquitin-proteosome proteolytic pathway. Cell 79:13–22[CrossRef][Medline]
  35. Crook T, Ludwig RL, Marston NJ, Willkomm D, Vousden KH 1996 Sensitivity of p53 lysine mutants to ubiquitin-directed degradation targeted by human papillomavirus E6. Virology 217:285–292[CrossRef][Medline]
  36. Ciechanover A, Digiuseppe JA, Bercovich B, Orian A, Richter J, Schwartz AL, Brodeur GM 1991 Degradation of nuclear oncogenes by the ubiquitin system in vitro. Proc Natl Acad Sci USA 88:139–143[Abstract/Free Full Text]
  37. Vogelstein B, Kinzler KW 1992 p53 function and dysfunction. Cell 70:523–526[CrossRef][Medline]
  38. Nigro JM, Baker SJ, Preisinger AC, Jessup JM, Hostetter R, Cleary K, Bigner SH, Davidson N, Baylin S, Devilee P, Glover T, Collins FS, Weston A, Modali R, Harris CC, Vogelstein B 1989 Mutations in the p53 gene occur in diverse human types. Nature 342:705–708[CrossRef][Medline]
  39. Kenneth WK, Bert V 1997 Gatekeepers and caretakers. Nature 386:761–763[CrossRef][Medline]



This article has been cited by other articles:


Home page
 J. Clin. Endocrinol. Metab.Home page
H. Sasaki, N. Ohara, Q. Xu, J. Wang, D. A. DeManno, K. Chwalisz, S. Yoshida, and T. Maruo
A Novel Selective Progesterone Receptor Modulator Asoprisnil Activates Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL)-Mediated Signaling Pathway in Cultured Human Uterine Leiomyoma Cells in the Absence of Comparable Effects on Myometrial Cells
J. Clin. Endocrinol. Metab., February 1, 2007; 92(2): 616 - 623.
[Abstract] [Full Text] [PDF]

Home page
 Mol Hum ReprodHome page
C.J. Loy, S. Evelyn, F.K. Lim, M.H. Liu, and E.L. Yong
Growth dynamics of human leiomyoma cells and inhibitory effects of the peroxisome proliferator-activated receptor-{gamma} ligand, pioglitazone
Mol. Hum. Reprod., August 1, 2005; 11(8): 561 - 566.
[Abstract] [Full Text] [PDF]

Home page
 J. Clin. Endocrinol. Metab.Home page
S.-J. Tsai, S.-J. Lin, Y.-M. Cheng, H.-M. Chen, and L.-Y. C. Wing
Expression and Functional Analysis of Pituitary Tumor Transforming Growth Factor-1 in Uterine Leiomyomas
J. Clin. Endocrinol. Metab., June 1, 2005; 90(6): 3715 - 3723.
[Abstract] [Full Text] [PDF]

Home page
 Hum ReprodHome page
A. Shushan, N. Rojansky, N. Laufer, B. Y. Klein, Z. Shlomai, R. Levitzki, Z. Hartzstark, and H. Ben-Bassat
The AG1478 tyrosine kinase inhibitor is an effective suppressor of leiomyoma cell growth
Hum. Reprod., September 1, 2004; 19(9): 1957 - 1967.
[Abstract] [Full Text] [PDF]

Home page
 Hum Reprod UpdateHome page
T. Maruo, N. Ohara, J. Wang, and H. Matsuo
Sex steroidal regulation of uterine leiomyoma growth and apoptosis
Hum. Reprod. Update, May 1, 2004; 10(3): 207 - 220.
[Abstract] [Full Text] [PDF]

Home page
 Hum ReprodHome page
T. Yamada, S. Nakago, O. Kurachi, J. Wang, S. Takekida, H. Matsuo, and T. Maruo
Progesterone down-regulates insulin-like growth factor-I expression in cultured human uterine leiomyoma cells
Hum. Reprod., April 1, 2004; 19(4): 815 - 821.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Submit a related Letter to the Editor
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Gao, Z.
Right arrow Articles by Maruo, T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Gao, Z.
Right arrow Articles by Maruo, T.
Right arrowPubmed/NCBI databases
*Compound via MeSH
*Substance via MeSH
Hazardous Substances DB
*ESTRADIOL
*PROGESTERONE
Medline Plus Health Information
*Uterine Cancer
*Uterine Fibroids

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Endocrinology Endocrine Reviews J. Clin. End. & Metab.
Molecular Endocrinology Recent Prog. Horm. Res. All Endocrine Journals