|
|
||||||||
ORIGINAL RESEARCH |
From the Department of Obstetrics and Gynecology, Saga Medical School, Saga, Japan.
Address reprint requests to: Tsuyoshi Iwasaka, MD, PhD, Department of Obstetrics and Gynecology, Saga Medical School, 1-1, Nabeshima 5-chome, 849-8501 Saga, Japan
| Abstract |
|---|
|
|
|---|
Methods: We examined eutopic and ectopic endometria from 23 patients with adenomyosis. To obtain evidence for the induction of programmed cell death, apoptotic cells were identified using a modified terminal deoxynucleotidyltransferase-biotin nick end-labeling method. To evaluate cell death repressor activity, bcl-2 gene expression was examined using immunohistochemical staining. As a proliferative marker, Ki-67 expression was also examined immunohistochemically.
Results: In the eutopic endometrium, apoptosis was most frequently observed in epithelial cells during mid- to late secretory phases, although it was rarely found during early proliferative through early secretory phases (P < .01). In contrast, bcl-2 gene expression inversely correlated with the appearance of apoptosis. A similar tendency was observed in stromal cells. In the ectopic endometrium of adenomyosis, endometrial dating revealed that secretory change was rare, even in the secretory phase, and that induction of apoptotic cells as well as bcl-2 gene expression showed no cyclic change. In stromal cells of the ectopic endometrium, apoptosis was more frequent than was seen in the eutopic endometrium, in all menstrual phases (P < .05). Ki-67 was constantly expressed in the glandular epithelium of the ectopic endometrium, irrespective of the menstrual phases, whereas in the secretory phase it was less expressed in the eutopic endometrium of functional and basal layers (P < .01).
Conclusion: The induction of apoptosis seems to be regulated by hormonal changes in the eutopic endometrium and has an inverse correlation with bcl-2 gene expression. The ectopic endometrium in adenomyosis is rarely influenced by hormonal change and has different biologic and proliferative properties than events observed in the eutopic endometrium findings, which strongly suggest that the adenomyotic lesion does not originate in the basal endometrium.
Apoptosis is a process of programmed cell death by which the numbers of cells in a variety of tissues, including those in the human uterus, are physiologically regulated and the process differs from events related to necrosis.1 Microscopically, apoptosis is associated with cell shrinkage; the condensation of chromatin; and the formation of small, spherical, membrane-bound organelles, referred to as apoptotic bodies,1 and DNA fragmentation is evident.2
The human endometrium undergoes characteristic proliferative, secretory, and menstrual phases as a result of cycle-related changes in accordance with levels of steroid hormones. Apoptosis is found primarily in glandular cells during the secretory phase, whereas it is less frequent in proliferative endometrium,3,4 thereby suggesting an important role for apoptosis in the menstrual cycle. The protein encoded by the bcl-2 gene was detected using a monoclonal antibody and validated immunohistochemical techniques.5 This protein has been reported to play an important role as a cell death repressor.6,7 There is an inverse correlation of bcl-2 protein expression with the induction of apoptosis in the normal human uterine endometrium.4,8,9 There are reports on the induction of apoptosis in endometriotic lesions; however, there is no consensus on the mode of appearance of apoptosis, compared with the eutopic endometrium.10,11 Less is known about apoptosis and bcl-2 expression in the ectopic endometrium of adenomyotic lesions. A proliferative marker, Ki-67, is expressed only in the nucleus of cycling proliferative but not in resting cells.12 Expression of Ki-67 is comparatively greater in the functionalis than the basalis endometrium,13 and immunoreactivity of Ki-67 in endometrial stromal cells is weak during the proliferative phase but increased in secretory phase endometrium. There have been two reports on proliferative activity in endometriotic lesions; however, the results are conflicting. Li et al14 noted the higher proliferative activity in endometriotic lesions compared with eutopic endometrium, whereas Jones et al15 found a lower proliferative activity in these lesions. We find no reports on details of Ki-67 expression in adenomyotic lesions.
Our preliminary data on detection of apoptosis in adenomyotic lesions indicated that induction of apoptosis in these lesions is more frequent than in the corresponding eutopic endometrium, which suggests that the ectopic endometrium in adenomyotic lesions might have properties that differ from those in the eutopic endometrium. There are various opinions as to the origin of the endometrium found in adenomyotic lesions.16 Cullen17 suggested that it has its source in the endometrium lining of the uterine cavity, and it is now universally accepted that the endometrium of the uterine cavity penetrates interspaces of the uterine wall. On the other hand, von Recklinghausen (Von Recklinghausen F. Adenomyoma and cystadenomas of the wall of the uterus and tube: Their origin as remnants of the Wolffian body. Wien Klin Wochenschr 1896;8:530) proposed that the ectopic endometrium is the result of embryonic cell rests. The theory of origin of müllerian rests has been supported by investigators who suggested the possibility that the histopathogenesis of adenomyotic lesions is related to metaplasia of müllerian remnants.18,19
The present study was performed to determine whether the adenomyotic lesion has its origin in the endometrial lining of the uterine cavity, especially in the basal layer. For this purpose, the dynamics of induction of apoptosis, bcl-2 gene expression, and Ki-67 expression were examined in adenomyotic lesions and the findings were compared with those in the corresponding eutopic endometrium.
| Materials and Methods |
|---|
|
|
|---|
DNA fragmentation associated with apoptosis was detected using a modified terminal deoxynucleotidyl-transferase-biotin nick end-labeling (TUNEL) method,21 for all 23 cases. The 4-µmthick sections from paraffin-embedded blocks were deparaffinized, immersed in 0.3% H2O2 to block endogenous peroxidase, and then treated with 20 µg/mL proteinase K for 15 minutes and incubated at 37C for 1 hour in a solution including terminal deoxynucleotidyltransferase (TdT) and digoxigenin-labeled deoxyuridinetriphosphate. After a wash, they were treated with a peroxidase-labeled anti-digoxigenin antibody for 30 minutes and stained with 3,3'-diaminobenzidine containing 0.01% H2O2, as the chromogen. The slides were counterstained with hematoxylin. A normal thymus of a fetus at 20 weeks gestation served as the positive control, and omission of the enzyme TdT as the negative control.
Serial sections were deparaffinized followed by immunostaining with bcl-2 antibody (bcl-2 124; Dako Ltd, Glostrup, Denmark) or with Ki-67 monoclonal antibody (Dakopatts, Copenhagen, Denmark); the avidinbiotin peroxidase complex method was used. We compared bcl-2 immunoreactivity and the Ki-67 labeling index in eutopic and ectopic endometria. For negative control the primary antibody was replaced by phosphate-buffered saline.
The quantitation of apoptosis, bcl-2 expression, and Ki-67 expression was carried out in a blind fashion by two independent observers. Each observer counted at least 1000 cells in more than 10 randomly chosen fields per case, and the number of positive cells per 1000 cells was designated as the apoptotic index on TUNEL-stained sections. The extent of the staining in the case of bcl-2 expression was scored as follows: strongly positive, 3; definite positive, 2; weakly positive, 1; and negative, 0. The Ki-67 labeling index was determined by counting at least 1000 cells in more than ten different areas of each section and was expressed in percentage. Interobserver agreement was 82%, 85%, and 91% for the analysis of apoptosis, bcl-2 expression, and Ki-67 expression, respectively.
For statistical analysis, Kruskal-Wallis test was used for multiple comparisons among all groups, and Wilcoxons paired test was used for comparison of each pair of groups. A level of P < .05 was considered to have statistical significance.
| Results |
|---|
|
|
|---|
|
|
|
|
Ki-67positive cells were observed in 5.82% of epithelial cells of the functional layer of the eutopic endometrium during the proliferative phase, and the number was significantly higher than that in the secretory phase (1.21%, P < .01) and that in the menstrual phase (1.02%, P < .01), respectively (Table 4
, Figure 2A and B
). On the other hand, Ki-67 expression was constantly high in epithelial cells of the ectopic endometrium, irrespective of the phases of the menstrual cycle (Figure 2C
). Labeling indices in the ectopic endometrium during secretory and menstrual phases were significantly higher than those in the eutopic endometrium of the functional layer (P < .01 and P < .05, respectively) (Table 4
). The labeling index in adenomyotic lesions during the secretory phase was also significantly higher than that in the eutopic glandular epithelium of the basal layer (P < .01) (Table 4
). Proliferative activity in stromal cells of the ectopic endometrium during the secretory phase was higher than that in the basal layer of the eutopic endometrium; however, the difference was not significant (Table 4
).
|
|
| Discussion |
|---|
|
|
|---|
In the present study, we found cyclic change of induction of apoptotic cells and the inverse correlation of bcl-2 expression in normal human endometrium during the menstrual cycle, consistent with data in previous reports.10,23,24 We also noted no cyclic change in apoptosis and bcl-2 expression in the ectopic endometrium in adenomyosis. We found only one report that referred to apoptosis and bcl-2 expression in adenomyotic lesions. Suganuma et al11 analyzed 12 adenomyotic lesions and stated that apoptotic cells were rarely found in adenomyotic lesions or in the eutopic endometrium, findings incompatible with previous observations and with our data. They reported that bcl-2 staining was positive in all adenomyotic tissues in the proliferative phase but in none of those in the secretory phase. This would suggest that bcl-2 expression in the adenomyotic endometrium shows a cyclic change, which is also incompatible with our observations.
In the analysis of proliferative activity, Ki-67 expression was high in the proliferative phase of the functional eutopic endometrium but was low in the secretory and menstrual phases. A similar result was found in the secretory phase of the basal eutopic endometrium. Li et al14 examined the eutopic endometrium and endometriotic lesions when immunostaining for proliferating cell nuclear antigen and noted that staining in the glandular epithelium reached a maximum in the proliferative phase and decreased in the secretory phase in both functional and basal layers of the eutopic endometrium, which is consistent with our observation. We found that Ki-67 expression in adenomyotic lesions was constantly high, irrespective of aspects of the menstrual cycle, findings differing from the eutopic endometrium in the basal layer. We observed that induction of apoptosis was remarkably high in stromal cells in adenomyotic lesions, compared with findings in the basal layer of the eutopic endometrium. The difference would reflect the constant proliferation of the ectopic endometrium among the narrow spaces of the myometrium. This mechanism can be explained by Moultons observation that increasing the density of stromal cell cultures increases levels of apoptosis.25
On the basis of findings of apoptosis, bcl-2 expression, and Ki-67 staining in adenomyotic lesions, we conclude that adenomyotic lesions do have a constant proliferative activity that is rarely influenced by endogeneous sex steroids, especially by progesterone. As to the pathogenesis of adenomyosis, the direct extension theory was proposed by Cullen,17 and has been widely accepted. However, evidence that the adenomyotic endometrium has different biologic or proliferative activities from the eutopic endometrium in the basal layer does support the metaplasia theory of müllerian remnants, as emphasized by Dougherty and Anderson18 and recently by Nisolle and Donnez for the pathogenesis of adenomyotic lesions.19 If one explains this evidence according to the direct extension theory, it would be essential to presuppose that only a selected cell population in the basal layer that is highly proliferative and less responsive to progesterone invades diffusely and deeply into the myometrium.
| Footnotes |
|---|
Received September 2, 1998. Received in revised form December 30, 1998. Accepted January 13, 1999.
| References |
|---|
|
|
|---|
2. Arends MJ, Morris RG, Wyllie AH. Apoptosis: The role of the endonuclease. Am J Pathol 1990;136:593608.[Abstract]
3. Tabibzadeh S, Kong QF, Satyaswaroop PG. Distinct regional and menstrual cycle dependent distribution of apoptosis in human endometrium. Potential regulatory role of T cells and TNF-alpha. Endocr J 1994;2:8795.
4. Kokawa K, Shikone T, Nakano R. Apoptosis in the human uterine endometrium during the menstrual cycle. J Clin Endocrinol Metab 1996;81:41447.
5. Tsujimoto Y, Cossman J, Jaffe E, Croce CM. Involvement of the bcl-2 gene in human follicular lymphoma. Science 1985;228:14403.
6. Yang E, Korsmeyer SJ. Molecular thanatopsis: A discourse on the BCL-2 family and cell death. Blood 1996;88:386401.
7. Reed JC. Bcl-2 and the regulation of programmed cell death. J Cell Biol 1994;124:16.
8. Gompel A, Sabourin C, Martin A, Yaneva H, Audouin J, Decroix Y, et al. Bcl-2 expression in normal endometrium during the menstrual cycle. Am J Pathol 1994;144:1195202.[Abstract]
9. Otsuki Y, Misaki O, Sugimoto O, Ito Y, Tsujimoto Y, Akao Y. Cyclic bcl-2 gene expression in human uterine endometrium during menstrual cycle. Lancet 1994;344:289.[Medline]
10. Watanabe H, Kanzaki H, Narukawa S, Inoue T, Katsuragawa H, Kaneko Y, et al. Bcl-2 and Fas expression in eutopic and ectopic human endometrium during the menstrual cycle in relation to endometrial cell apoptosis. Am J Obstet Gynecol 1997;176:3608.[Medline]
11. Suganuma N, Harada M, Furuhashi M, Nawa A, Kikkawa F. Apoptosis in human endometrial and endometriotic tissues. Horm Res 1997;48:427.
12. Gerdes J, Lemke H, Baisch H, Wacker HH, Schwab U, Stein H. Cell cycle analysis of a cell proliferation associated human nuclear antigen defined by the monoclonal antibody Ki-67. J Immunol 1984;133:17105.[Abstract]
13. Tabibzadeh S. Immunoreactivity of human endometrium: Correlation with endometrial dating. Fertil Steril 1990;54:62431.[Medline]
14. Li SF, Nakayama K, Masuzawa H, Fujii S. The number of proliferating cell nuclear antigen positive cells in endometriotic lesions differs from that in the endometrium. Analysis of PCNA positive cells during the menstrual cycle and in postmenopause. Virchows Arch A Pathol Anat Histopathol 1993;423:25763.[Medline]
15. Jones RK, Bulmer JN, Searle RF. Immunohistochemical characterization of proliferation, oestrogen receptor and progesterone receptor expression in endometriosis: Comparison of eutopic and ectopic endometrium with normal cycling endometrium. Hum Reprod 1995;10:32729.
16. Witz CA, Schenken RS. Pathogenesis. Semin Reprod Endocrinol 1997;15:199208.[Medline]
17. Cullen TS. Adenomyoma of uterus. Philadelphia, PA: WB Saunders Co, 1908:2227.
18. Dougherty CM, Anderson MR. Endometriosis and adenomyosis. Am J Obstet Gynecol 1964;89:2340.[Medline]
19. Nisolle M, Donnez J. Peritoneal endometriosis, ovarian endometriosis, and adenomyotic nodules of the rectovaginal septum are three different entities. Fertil Steril 1997;68:58596.[Medline]
20. Noyes RW, Hertig AT, Rock J. Dating the endometrial biopsy. Fertil Steril 1950;1:325.
21. Gavrieli Y, Sherman Y, Ben-Sasson SA. Identification of programmed cell death in situ via specific labeling of nuclear DNA fragmentation. J Cell Biol 1992;119:493501.
22. Hopwood D, Levison DA. Atrophy and apoptosis in the cyclical human endometrium. J Pathol 1975;119:15966.
23. Kokawa K, Shikone T, Nakano R. Apoptosis in the human uterine endometrium during the menstrual cycle. J Clin Endocrinol Metab 1996;81:41447.
24. Tao XJ, Tilly KI, Maravei DV, Shifren JL, Krajewski S, Reed JC, et al. Differential expression of members of the bcl-2 gene family in proliferative and secretory human endometrium: Glandular epithelial cell apoptosis is associated with increased expression of bax. J Clin Endocrinol Metab 1997;82:273846.
25. Moulton BC. Transforming growth factor-ß stimulates endometrial stromal apoptosis in vitro. Endocrinology 1994;134:105560.[Abstract]
This article has been cited by other articles:
![]() |
J.-H. Yang, M.-Y. Wu, C.-D. Chen, M.-J. Chen, Y.-S. Yang, and H.-N. Ho Altered apoptosis and proliferation in endometrial stromal cells of women with adenomyosis Hum. Reprod., April 1, 2007; 22(4): 945 - 952. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. G. Goumenou, I. M. Matalliotakis, M. Tzardi, Y. G. Fragouli, N. G. Mahutte, and A. Arici Apoptosis and Differential Expression of Apoptosis-Related Proteins in Endometriotic Glandular and Stromal Cells Reproductive Sciences, July 1, 2004; 11(5): 318 - 322. [Abstract] [PDF] |
||||
![]() |
M. Ueda, Y. Yamashita, M. Takehara, Y. Terai, K. Kumagai, K. Ueki, K. Kanda, H. Yamaguchi, D. Akise, Y.-C. Hung, et al. Survivin Gene Expression in Endometriosis J. Clin. Endocrinol. Metab., July 1, 2002; 87(7): 3452 - 3459. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. E. Hale, C. L. Hughes, and J. M. Cline Endometrial Cancer: Hormonal Factors, the Perimenopausal ""Window of Risk,"" and Isoflavones J. Clin. Endocrinol. Metab., January 1, 2002; 87(1): 3 - 15. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Maruo, J.B. Laoag-Fernandez, P. Pakarinen, H. Murakoshi, I.M. Spitz, and E. Johansson Effects of the levonorgestrel-releasing intrauterine system on proliferation and apoptosis in the endometrium Hum. Reprod., October 1, 2001; 16(10): 2103 - 2108. [Abstract] [Full Text] [PDF] |
||||
![]() |
W.P. Dmowski, J. Ding, J. Shen, N. Rana, B.B. Fernandez, and D.P. Braun Apoptosis in endometrial glandular and stromal cells in women with and without endometriosis Hum. Reprod., September 1, 2001; 16(9): 1802 - 1808. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |