Sources/Clones
Abbott (PgR-ICA), Becton Dickinson (PR33, PR4-12), Biogenesis (1A6), Biogenex (PgR-1A), Dako (1A6, polyclonal), Immunotech (PR10A9), Labvision Corp (HPRA2-7), Novocastra (1A6), Oncor (4.12) and Zymed (1A6).
Fixation/Preparation
Most antibody clones currently available are immunoreactive in routinely fixed, paraffin-embedded tissues and enhanced after HIER. Enzymatic predigestion is not required (Leong & Milios, 1993).
Background
In selected target tissues, estrogens have been found to stimulate not only mitogenesis but also the synthesis of specific proteins. One of these estrogen-induced proteins is the progesterone receptor (PR). Progesterone and synthetic progestins activate the receptor, provoke its phosphorylation and DNA-binding ability and induce its regulatory activities. Since the PR is an estrogen-inducible protein, its expression is indicative of an intact estrogen receptor pathway and may identify tumors that are hormonally responsive to estrogen, thereby improving the overall predictive value of steroid receptor assays in selected tumors such as breast carcinoma (Guichon-Mantel et al, 1996).
The PR displays the typical three-domain structure of the steroid-thyroid receptor family. The central domain contains two ''zinc finger" structures responsible for the specific recognition of the cognate DNA sequences. The carboxyl-terminal domain contains the hormone and antihormone binding sites. The complete organization of the human PR gene has been determined. It spans over 90 kb and contains eight exons. The first exon encodes the N-terminal part of the receptor, the DNA-binding domain is encoded by two exons, each corresponding to one zinc finger, and the steroid-binding domain is encoded by five exons.
The signal responsible for the nuclear localization of the PR is a complex one. The receptor continuously shuttles between the nucleus and cytoplasm. The receptor diffuses into the cytoplasm and is constantly and actively transported back into the nucleus, similar to the phenomenon for estradiol and glucocorticosteroid receptors. Immunolocalization of PR is confined to the nucleus.
Applications
The value of estrogen and progesterone receptor assays in predicting response to hormonal treatment in advanced breast cancer patients has been well supported by both studies employing cytosol-based ligandbinding methods and immunohistochemical assays, the prognostic utility being strongest in premenopausal women. Approximately 50% of breast cancers are ER+ PR+, 20% ER+ PR-, 5% ERPR+, and 25% ER- PR-. Those women whose cancers express both ER and PR show the greatest likelihood of responding to endocrine treatment. Using conventional biochemical assays, the response rate is about 77% for ER+ PR+ tumors, 46% for ER- PR+, 27% for ER+ PR- and 11% for ER- PR- tumors. However, it is clinically recognized that a small proportion of women with tumors which are receptor negative will show a positive response to hormonal therapy and as many as one third of those with receptor-positive tumors may fail to respond to such treatment. The significance of breast carcinomas biochemically negative for estrogen receptor (ER), but positive for PR, is poorly understood. It has been proposed that these tumors, more common in younger women, contain ER whose presence is masked in a biochemical binding assay by endogenous estrogen. Such tumors should be positive for ER by immunocytochemical assay but this was not proven in one study, which found that ER-PR+ tended to have larger tumor size and higher histologic grade and Sphase fractions compared to ER + PR + tumors. It was concluded that biochemically ER- PR + breast carcinomas are biologically different from ER + PR + tumors (Keshgegian, 1994). There has been some suggestion that PR may be a more important predictor as there are more responders among patients with ER-PR+ compared to ER+PR- tumors. In some series, although this remains to be proven, the prognostic advantage of steroid receptor positivity was lost after 4-5 years of follow up (Lipponen et al, 1992). As with the estrogen receptor, there is increasing evidence that immunohistological assays provide more accurate prognostication than cytosol-based methods (Mohammed et al, 1986; Pertschuk et al, 1996).
Comments
We employ PgR-ICA which is enhanced following HIER. Immunostaining is further enhanced following HIER in TRS (Dako) as compared to citrate buffer (Leong et al, 1996; MacGrogan et al, 1996). Consistent immunostaining is obtained in cytological preparations that have been fixed in 10% formalin following complete air drying. HIER should be used (Suthipintawong et al, 1997).
Problems associated with reporting of results and the relevance of objective assessment of immunostains with image analysis equipment are discussed under "estrogen receptor".
References
•Guichon-Mantel A, Delabre K, Lescop P, Milgrom E 1996. Intracellular traffic of steroid hormone receptors. Journal of Steroid Biochemistry and Molecular Biology; 56: 3-9.
•Keshgegian AA 1994. Biochemically estrogen receptor-negative, progesterone receptor-positive breast carcinoma. Immunocytochemical hormone receptors and prognostic factors. Archives of Pathology and Laboratory Medicine; 118: 240-244.
•Leong AS-Y, Milios J 1993. Comparison of antibodies to estrogen and progesterone receptors and the influence of microwave antigen retrieval. Applied Immunohistochemistry; 1: 282-288.
•Leong AS-Y, Milios J, Leong FJ 1996. Epitope retrieval with microwaves. A comparison of citrate buffer and EDTA with three commercial retrieval solutions. Applied Immunohistochemistry; 4: 201-207.
•Lipponen P, Aaltomas S, Eskelinen M 1992. The changing importance of prognostic factors in breast cancer during long term follow-up. International Journal of Cancer; 51: 698-702.
•MacGrogan G, Soubeyran I, De Mascarel I et al 1996. Immunohistochemical detection of progesterone receptors in breast invasive ductal carcinomas: a correlative study of 942 cases. Applied Immunohistochemistry; 4: 219-227.
•Mohammed RH, Lakatua DJ, Haus E, Yasmineh WJ 1986. Estrogen and progesterone receptors in human breast cancer: correlation with histologic subtype and degree of differentiation. Cancer; 58: 1076-1081.
•Pertschuk L, Feldman J, Kim Y-D et al 1996. Estrogen receptor (ER) immunocytochemistry in paraffin with ER1D5 predicts breast cancer endocrine response more accurately that H222Sp in frozen sections or cytosol-based ligand binding assays. Cancer; 77: 2541-2549.
•Suthipintawong C, Leong AS-Y, Chan KW, Vinyuvat S 1997. Immunostaining of estrogen receptor, progesterone receptor, MIB1 and c-erbB-2 in cytological preparations a simplified method. Diagnostic Cytopathology 17: 127-133.
Bibliografia
Manual of diagnostic antibodies for immunohistology / Anthony S.-Y. Leong, Kumarasen Cooper, F. Joel W.-M. Leong.
Abbott (PgR-ICA), Becton Dickinson (PR33, PR4-12), Biogenesis (1A6), Biogenex (PgR-1A), Dako (1A6, polyclonal), Immunotech (PR10A9), Labvision Corp (HPRA2-7), Novocastra (1A6), Oncor (4.12) and Zymed (1A6).
Fixation/Preparation
Most antibody clones currently available are immunoreactive in routinely fixed, paraffin-embedded tissues and enhanced after HIER. Enzymatic predigestion is not required (Leong & Milios, 1993).
Background
In selected target tissues, estrogens have been found to stimulate not only mitogenesis but also the synthesis of specific proteins. One of these estrogen-induced proteins is the progesterone receptor (PR). Progesterone and synthetic progestins activate the receptor, provoke its phosphorylation and DNA-binding ability and induce its regulatory activities. Since the PR is an estrogen-inducible protein, its expression is indicative of an intact estrogen receptor pathway and may identify tumors that are hormonally responsive to estrogen, thereby improving the overall predictive value of steroid receptor assays in selected tumors such as breast carcinoma (Guichon-Mantel et al, 1996).
The PR displays the typical three-domain structure of the steroid-thyroid receptor family. The central domain contains two ''zinc finger" structures responsible for the specific recognition of the cognate DNA sequences. The carboxyl-terminal domain contains the hormone and antihormone binding sites. The complete organization of the human PR gene has been determined. It spans over 90 kb and contains eight exons. The first exon encodes the N-terminal part of the receptor, the DNA-binding domain is encoded by two exons, each corresponding to one zinc finger, and the steroid-binding domain is encoded by five exons.
The signal responsible for the nuclear localization of the PR is a complex one. The receptor continuously shuttles between the nucleus and cytoplasm. The receptor diffuses into the cytoplasm and is constantly and actively transported back into the nucleus, similar to the phenomenon for estradiol and glucocorticosteroid receptors. Immunolocalization of PR is confined to the nucleus.
Applications
The value of estrogen and progesterone receptor assays in predicting response to hormonal treatment in advanced breast cancer patients has been well supported by both studies employing cytosol-based ligandbinding methods and immunohistochemical assays, the prognostic utility being strongest in premenopausal women. Approximately 50% of breast cancers are ER+ PR+, 20% ER+ PR-, 5% ERPR+, and 25% ER- PR-. Those women whose cancers express both ER and PR show the greatest likelihood of responding to endocrine treatment. Using conventional biochemical assays, the response rate is about 77% for ER+ PR+ tumors, 46% for ER- PR+, 27% for ER+ PR- and 11% for ER- PR- tumors. However, it is clinically recognized that a small proportion of women with tumors which are receptor negative will show a positive response to hormonal therapy and as many as one third of those with receptor-positive tumors may fail to respond to such treatment. The significance of breast carcinomas biochemically negative for estrogen receptor (ER), but positive for PR, is poorly understood. It has been proposed that these tumors, more common in younger women, contain ER whose presence is masked in a biochemical binding assay by endogenous estrogen. Such tumors should be positive for ER by immunocytochemical assay but this was not proven in one study, which found that ER-PR+ tended to have larger tumor size and higher histologic grade and Sphase fractions compared to ER + PR + tumors. It was concluded that biochemically ER- PR + breast carcinomas are biologically different from ER + PR + tumors (Keshgegian, 1994). There has been some suggestion that PR may be a more important predictor as there are more responders among patients with ER-PR+ compared to ER+PR- tumors. In some series, although this remains to be proven, the prognostic advantage of steroid receptor positivity was lost after 4-5 years of follow up (Lipponen et al, 1992). As with the estrogen receptor, there is increasing evidence that immunohistological assays provide more accurate prognostication than cytosol-based methods (Mohammed et al, 1986; Pertschuk et al, 1996).
Comments
We employ PgR-ICA which is enhanced following HIER. Immunostaining is further enhanced following HIER in TRS (Dako) as compared to citrate buffer (Leong et al, 1996; MacGrogan et al, 1996). Consistent immunostaining is obtained in cytological preparations that have been fixed in 10% formalin following complete air drying. HIER should be used (Suthipintawong et al, 1997).
Problems associated with reporting of results and the relevance of objective assessment of immunostains with image analysis equipment are discussed under "estrogen receptor".
References
•Guichon-Mantel A, Delabre K, Lescop P, Milgrom E 1996. Intracellular traffic of steroid hormone receptors. Journal of Steroid Biochemistry and Molecular Biology; 56: 3-9.
•Keshgegian AA 1994. Biochemically estrogen receptor-negative, progesterone receptor-positive breast carcinoma. Immunocytochemical hormone receptors and prognostic factors. Archives of Pathology and Laboratory Medicine; 118: 240-244.
•Leong AS-Y, Milios J 1993. Comparison of antibodies to estrogen and progesterone receptors and the influence of microwave antigen retrieval. Applied Immunohistochemistry; 1: 282-288.
•Leong AS-Y, Milios J, Leong FJ 1996. Epitope retrieval with microwaves. A comparison of citrate buffer and EDTA with three commercial retrieval solutions. Applied Immunohistochemistry; 4: 201-207.
•Lipponen P, Aaltomas S, Eskelinen M 1992. The changing importance of prognostic factors in breast cancer during long term follow-up. International Journal of Cancer; 51: 698-702.
•MacGrogan G, Soubeyran I, De Mascarel I et al 1996. Immunohistochemical detection of progesterone receptors in breast invasive ductal carcinomas: a correlative study of 942 cases. Applied Immunohistochemistry; 4: 219-227.
•Mohammed RH, Lakatua DJ, Haus E, Yasmineh WJ 1986. Estrogen and progesterone receptors in human breast cancer: correlation with histologic subtype and degree of differentiation. Cancer; 58: 1076-1081.
•Pertschuk L, Feldman J, Kim Y-D et al 1996. Estrogen receptor (ER) immunocytochemistry in paraffin with ER1D5 predicts breast cancer endocrine response more accurately that H222Sp in frozen sections or cytosol-based ligand binding assays. Cancer; 77: 2541-2549.
•Suthipintawong C, Leong AS-Y, Chan KW, Vinyuvat S 1997. Immunostaining of estrogen receptor, progesterone receptor, MIB1 and c-erbB-2 in cytological preparations a simplified method. Diagnostic Cytopathology 17: 127-133.
Bibliografia
Manual of diagnostic antibodies for immunohistology / Anthony S.-Y. Leong, Kumarasen Cooper, F. Joel W.-M. Leong.
