Expression of bcl-2 oncoprotein in renal cell tumours

Expression of bcl-2 is associated with inhibition of apoptosis and extension of cell survival. The importance of apoptosis in relation to the development and progression of renal cell neoplasia remains undefined so far. In order to determine the expression of bcl-2 oncoprotein in normal and neoplastic renal cells, 37 renal tumours were investigated by immunolabelling, including 13 clear cell carcinomas, ten tubulopapillary carcinomas, four chromophobic renal cell carcinomas, and ten oncocytomas. Twenty-six samples of adjacent normal renal tissue served as controls. bcl-2 expression was correlated with cell proliferation activity as estimated by Ki67 antigen expression, and p53 protein expression in the tumour samples. The results demonstrate that in the normal kidney, positive bcl-2 immunostaining was present in glomerular parietal epithelial cells, in distal tubular cells, and in sparse proximal tubule cells. Renal cell tumours showed heterogeneous bcl-2 expression according to the tumour cell type. While the majority of carcinomas of clear cell type were usually negative or contained sparsely distributed positive cells, all tubulopapillary carcinomas were consistently positive for bcl-2. In oncocytomas and chromophobic carcinomas, there was a low percentage of bcl-2 immunoreactive tumour cells; some nuclear bcl-2 positivity was detected in one chromophobic tumour. These findings indicate variable bcl-2 oncoprotein expression in different types of renal cell tumours, with the highest level of expression in tubulopapillary carcinomas. No clear relationship was found between nuclear grade, cell proliferation activity, and level of bcl-2 expression. p53 protein was detected in only one tubulopapillary carcinoma.     

子宫内膜腺癌组织中cyclinD1、PCNA和Ki-67的表达

目的　探讨cyclinD1、PCNA和Ki 6 7在子宫内膜腺癌组织中的表达及其意义。 方法　采用免疫组化S P法检测正常增生期子宫内膜 10例、单纯性增生 30例、复杂性增生 30例、非典型增生 30例和子宫内膜腺癌 4 7例组织中cyclinD1、PCNA和Ki 6 7的表达。结果　cyclinD1在增生期子宫内膜组织中未见阳性表达 ,在单纯性增生、复杂性增生、非典型增生和子宫内膜腺癌组织中的阳性表达率分别为 13 3%、16 7%、30 0 %和 5 7 8%。非典型增生和子宫内膜腺癌组织阳性表达率高于增生期宫内膜、单纯性和复杂性增生 (P <0 0 5 ) ,cyclinD1蛋白表达与子宫内膜腺癌临床分期、肌层浸润和淋巴结转移呈正相关 (P<0 0 5 ) ,而与肿瘤的分化程度无关 (P >0 0 5 )。PCNA和Ki 6 7在非典型增生组标记指数 (LI)高于增生期宫内膜、单纯性和复杂性增生组 ,子宫内膜腺癌组高于非典型增生组 (P <0 0 5 ) ,PCNA和Ki 6 7LI与肿瘤的分化程度、临床分期、肌层浸润和淋巴结转移呈正相关 (P <0 0 5 )。PCNA和Ki 6 7在cyclinD1阳性表达组的LI高于阴性组 (P <0 0 5 )。结论　cyclinD1蛋白过度表达可能在子宫内膜癌的发生、发展中起重要作用 ,其作用途径可能是通过促进细胞增殖而实现的。     

Expression of the retinoblastoma-related gene Rb2/p130 is downregulated in atypical endometrial hyperplasia and adenocarcinoma

The retinoblastoma-related gene Rb2/p130 encodes a protein that is a negative cell-cycle regulator normally expressed in a number of adult tissues. This protein shares many structural and functional features with the product of the retinoblastoma gene, one of the best-studied tumor-suppressor genes, and plays a fundamental role in growth control. The Rb2/p130 gene product associates with specific members of the E2F family and various cyclins, displaying a growth-suppressive activity specific for the G(0)/G(1) phases. It has been reported that Rb2/p130 is involved in the pathogenesis and progression of lung cancer and mesothelioma. We previously demonstrated for the first time that reduced immunohistochemical expression of Rb2/p130 was a strong independent predictor of poor outcome in endometrial cancer. The aim of the present study was to evaluate Rb2/p130 expression in normal, hyperplastic, and neoplastic endometrial lesions to determine whether the protein plays a significant role in endometrial carcinogenesis. We evaluated Rb2/p130 expression by immunohistochemistry staining in 102 specimens chosen to represent a spectrum of endometrial changes, including proliferative endometrium (n = 18), secretory endometrium (n = 18), simple or complex hyperplasia without atypia (n = 18), atypical hyperplasia (n = 18), and invasive carcinoma (n = 30). We found that Rb2/p130 was highly expressed in proliferative endometrium and in hyperplasia without atypia, the mean percentage of stained nuclei being 66% and 60%, respectively, but was downregulated in secretory endometrium, atypical hyperplasia, and carcinoma, with mean scores of 38%, 25%, and 22%, respectively. When categorized on a semiquantitative scale (negative v 1% to 50% v >50% positivity), endometrial cancer displayed significantly less staining than all other endometrial samples (P <.001). Poorly differentiated carcinomas (n = 9) showed a significantly lower immunoreactivity for Rb2/p130 than did well-differentiated carcinomas (n = 11; P =.005) and moderately differentiated carcinomas (n = 10; P =.03). In addition, atypical hyperplasia showed a significantly lower immunoreactivity than either proliferative endometrium (P =.003) or hyperplasia without atypia (P = 0.02). Our findings of a progressive decrease in Rb2/p130 expression from hyperplastic endometrium through atypical hyperplasia to poorly differentiated carcinomas suggest the involvement of this negative cell-cycle regulator in endometrial carcinogenesis. Furthermore, immunostaining for Rb2/p130 may prove diagnostically useful in the often difficult distinction between hyperplastic and atypical hyperplastic endometrium. HUM PATHOL 32:360-367.     

子宫内膜样腺癌中TBX2、PAX9的表达及其相关性

目的 探讨TBX2、PAX9在正常子宫内膜、子宫内膜增殖症和子宫内膜样腺癌(endometrioid adenocarcinoma,EA)组织中的表达及临床病理学意义.方法 采用组织芯片技术和免疫组化检测30例正常子宫内膜组织、30例单纯性增生内膜、30例复杂伴不典型性增生内膜、82例EA组织中TBX2、PAX9蛋白的表达.结果 TBX2蛋白在子宫内膜样腺癌中的阳性表达率明显高于正常子宫内膜和子宫内膜增殖症(P均＜0.01),TBX2过表达与组织学分级、临床分期、浸润程度均有相关性(P＜0.01,P＜0.05,P＜0.01),与淋巴结转移无相关性(P＞0.05);PAX9蛋白在子宫内膜样腺癌中的阳性表达率明显高于正常子宫内膜、子宫内膜单纯性增生(P均＜0.01),而和复杂伴不典型性增生之间没有统计学意义(P＞0.05),在复杂伴不典型增生中表达明显高于正常子宫内膜和单纯性增生内膜(P均＜0.01),PAX9阳性表达与组织学分级、临床分期、浸润程度均有相关性(P＜0.01,P＜0.01,P＜0.05),但与淋巴结转移无相关性(P＞0.05).TBX2与PAX9蛋白呈正相关(rs=0.427,P＜0.01).结论 TBX2和PAX9均在子宫内膜样腺癌中发生、发展中发挥重要作用,联合检测其表达可为子宫内膜样腺癌的早期诊断、预后判断提供有价值的指标.     

Loss of BAF250a (ARID1A) is frequent in high-grade endometrial carcinomas

Mutation of the ARID1A gene and loss of the corresponding protein BAF250a has recently been described as a frequent event in clear cell and endometrioid carcinomas of the ovary. To determine whether BAF250a loss is common in other malignancies, immunohistochemistry (IHC) for BAF250a was performed on tissue microarrays (TMAs) in more than 3000 cancers, including carcinomas of breast, lung, thyroid, endometrium, kidney, stomach, oral cavity, cervix, pancreas, colon and rectum, as well as endometrial stromal sarcomas, gastrointestinal stromal tumours, sex cord-stromal tumours and four major types of lymphoma (diffuse large B cell lymphoma, primary mediastinal B cell lymphoma, mantle cell lymphoma and follicular lymphoma). We found that BAF250a loss is frequent in endometrial carcinomas but infrequent in other types of malignancies, with loss observed in 29% (29/101) of grade 1 or 2 and 39% (44/113) of grade 3 endometrioid carcinomas of the endometrium, 18% (17/95) of uterine serous carcinomas and 26% (6/23) of uterine clear cell carcinomas. Since endometrial cancers showed BAF250a loss, we stained whole tissue sections for BAF250a expression in nine cases of atypical hyperplasia and 10 cases of atypical endometriosis. Of the nine cases of complex atypical endometrial hyperplasia, all showed BAF250a expression; however, of 10 cases of atypical endometriosis (the putative precursor lesion for ovarian clear cell and endometrioid carcinoma), one case showed loss of staining for BAF250a in the atypical areas, with retention of staining in areas of non-atypical endometriosis. This was the sole case that recurred as an endometrioid carcinoma, indicating that BAF250a loss may be an early event in carcinogenesis. Since BAF250a loss is seen in endometrial carcinomas at a rate similar to that seen in ovarian carcinomas of clear cell and endometrioid type, and is uncommon in other malignancies, we conclude that loss of BAF250a is a particular feature of carcinomas arising from endometrial glandular epithelium.     

Apoptosis and the expression of Bax and Bcl-2 in hyperplasia and adenocarcinoma of the uterine endometrium

BACKGROUND: Apoptosis plays a crucial role in carcinogenesis in various tumours. This study was designed to investigate the occurrence of apoptosis and the expression of Bcl-2 and Bax proteins in endometrial tumours of corpus uteri. METHODS: Endometrial tissues were obtained from 20 patients with endometrioid adenocarcinoma, 16 patients with endometrial hyperplasia, and 4 patients with myoma uteri (which were used as controls). The occurrence of apoptosis was examined by using molecular biochemical techniques. The expression of Bcl-2 and Bax proteins was also investigated using immunohistochemical staining with appropriate antibodies. RESULTS: The labelling of DNA in situ indicated that apoptotic cells were sporadically seen in postmenopausal endometrium (5.2 +/- 2.1, n = 4) and endometrial hyperplasia without atypia (2.6 +/- 0.5, n = 9). In contrast, labelled cells were detected in atypical endometrial hyperplasia (15.9 +/- 2.2, n = 7), and their numbers increased intensely in adenocarcinoma (29.3 +/- 3.7, n = 20). Autoradiographic analysis revealed DNA laddering in many cases of carcinoma. Bcl-2 was highly immunopositive in hyperplasia without atypia (36.2 +/- 6.5%, n = 9), but was decreased in the atypical endometrial hyperplasia (16.3 +/- 4.8%, n = 7). Large fractions of the carcinoma (6.3 +/- 1.8%, n = 20) and normal endometrium (2.8 +/- 1.4%, n = 4) were immunonegative or slightly immunopositive to Bcl-2. In contrast, Bax immunoreactivity was more frequent and stronger in adenocarcinoma (43.6 +/- 4.1%, n = 20) than that in normal endometrium (17.6 +/- 6.7%, n = 4) and hyperplasia (7.2 +/- 2.2%, n = 16). CONCLUSIONS: These results suggest that cells in hyperplasia expressing Bcl-2 might have prolonged survival ability. Neoplastic cells in adenocarcinoma might show apoptosis in association with a decreased expression of Bcl-2 and an increased expression of Bax. Therefore, the frequency of apoptosis and the expression of Bcl-2 and Bax might be correlated with carcinogenesis in the uterine endometrium of humans.     

子宫内膜增生及内膜癌中PTEN、Ki-67蛋白的表达

目的　研究子宫内膜增生组织及内膜癌组织中PTEN、Ki 6 7蛋白的异常表达 ,探讨其与子宫内膜癌变的关系及作为早期癌变生物学标志的可能性。方法　应用免疫组化S P法对 12例正常增生期子宫内膜组织、4 0例子宫内膜增殖症组织、4 2例内膜腺癌组织中PTEN、Ki 6 7蛋白的表达进行研究。结果　在正常增生期子宫内膜、子宫内膜增殖症 (单纯增生、复杂型增生、不典型增生 )、子宫内膜腺癌组织中PTEN蛋白的阳性表达率呈递减趋势 ;Ki 6 7蛋白的阳性表达率呈递增趋势。等级相关分析结果显示PTEN、Ki 6 7表达异常与子宫内膜组织学分级均显著相关 (相关系数r分别为 - 0 5 4 1和 0 4 96 ,P值均<0 0 1)。子宫内膜癌与除不典型增生外的子宫内膜增殖症组织及正常增生期子宫内膜组织的PTEN、Ki 6 7蛋白表达差异有显著性 ,正常增生期子宫内膜、单纯增生与不典型增生组织的PTEN蛋白表达差异有显著性 ,不典型增生与单纯增生组织的Ki 6 7蛋白表达差异有显著性。PTEN、Ki 6 7蛋白表达存在负相关性 (r =- 0 4 2 8,P <0 0 1)。PTEN、Ki 6 7蛋白的表达与子宫内膜癌的手术分期、组织学分级、肌层浸润无关 (P >0 0 5 )。结论　PTEN、Ki 6 7蛋白的异常表达与子宫内膜的癌变过程相关 ,PTEN基因表达异常及细胞增殖异常与子宫内膜     

Expression of bcl-2 oncogene protein is prevalent in small cell lung carcinomas

To investigate the frequency of bcl-2 oncogene protein expression in small cell lung carcinoma (SCLC), immunohistochemical staining with a mouse-anti-human monoclonal antibody, bcl-2/124, was carried out on 60 formalin-fixed, paraffin-embedded SCLC samples obtained from surgical biopsy, and autopsy cases. bcl-2 protein was detected in 54 out of the 60 SCLCs. In 47 cases, more than half of the tumour cells stained positively. The staining intensity of the tumour cells was comparable to that of infiltrating lymphocytes in 37 cases, but varied from area to area and even from cell to cell. Negative data in six cases were found to be due to unsuitable fixation or embedding procedures rather than the absence of the antigen. bcl-2 oncogene protein may thus be expressed in most if not all SCLCs. bcl-2 may have potential diagnostic and therapeutic importance in SCLCs and non-SCLCs. Previous cytogenetic and molecular genetic analyses indicate that SCLCs carry a number of chromosomal abnormalities and it would follow from tpresent results that the abnormal expression of bcl-2 may also play a role in the pathogenesis of SCLC, by increasing tumour mass through inhibition of apoptosis as previously proposed. The diagnostic, prognostic, and therapeutic implications of these findings should be studied in greater detail.     

The value of endometrial cytology by scraping in 1,798 cases: screening in asymptomatic women and diagnosis in symptomatic ones

A study of 1,798 endometrial cytological samples, obtained with an "endocyte" (a disposable scraping device) and controlled in histology is presented. The method was tested for its usefulness in screening of precancerous lesions and preclinical cancer in 1,248 asymptomatic women and in the diagnosis of endometrial pathology in 550 symptomatic ones. The classification of hyperplasia into benign simplex and complex hyperplasia and atypical hyperplasia was followed; atypical hyperplasia, considered real intraepithelial neoplasia, was included in the positive cases. Histological verification was made chiefly on cell block in asymptomatic cytologically negative cases and either on curettage or hysterectomies in the others. The main endometrial cytological patterns are described. On the basis of findings, considering also endocyte's low cost, effectiveness, and ease of use, we think the method could be usefully employed in screening of endometrial cancer for an asymptomatic population. In symptomatic women, the use of histologic procedures is still preferable, and cytology cannot be considered a "first option" method.     

Low incidence of mbr bcl-2/JH fusion genes in Hodgkin's disease

Lymph node biopsies from 140 cases of Hodgkin's disease (HD) and from 30 non-malignant lesions were screened for the presence of t(14;18) translocations involving the major breakpoint region (mbr) of the bcl-2 gene and the joining region (J)_H of the immunoglobulin heavy chain gene, using a polymerase chain reaction (PCR) assay with subsequent nucleotide sequencing of amplified bcl-2/J_H junctional regions. Expression of the bcl-2 protein within the Hodgkin and Reed-Sternberg (HRS) cells was investigated in 86 cases of HD by immunohistochemistry on cryostat or paraffin sections. Although bcl-2 expression could be found in a proportion of neoplastic cells in up to one-third of HD cases, the frequency of t(14;18) gene fusions detected by PCR was low. We identified such gene fusions in only 3 out of 140 (2 per cent) HD cases, one biopsy of which presented with four clonally distinct bcl-2/J_H sequences. No t(14;18) was found in any of 30 reactive lymph node lesions. All fusion gene sequences were unique regarding the localization of the chromosome 14 and 18 breakpoints and the extranucleotide N-insertions. None of these gene fusions conformed to t(14;18) breakpoint sequences previously characterized in our laboratories. Our findings point to a mere coincidence in some cases of HD lesions and cells carrying a t(14;18) in the same biopsy and argue against a significant role of bcl-2 in the pathogenesis of HD.     

Expression and Clinical Significance of Ghrelin in Endometrial Hyperplasia and Carcinoma of Egyptian Patients

Endometrial carcinoma ranks the seventh most common malignant tumor worldwide. The distinction between atypical endometrial hyperplasia (AEH) and endometrial carcinoma, especially the well-differentiated grade, is particularly difficult with overlapping distinguishing criteria and small biopsy. Ghrelin is 28 amino acid peptide that is synthesized by gastric mucosa and is expressed in a variety of normal and tumor tissues. In endometrial tissue, it is expressed during the menstrual cycle, involved in the uterine development and cyclic growth. Data regarding role of Ghrelin in endometrial carcinoma are contradictory. In the present study, immunohistochemical expression of Ghrelin was evaluated in 55 endometrioid carcinoma cases, as well as 26 endometrial hyperplasia cases. The relationship between Ghrelin expression and clinicopathologic features of endometrioid carcinoma was studied as well. Ghrelin loss or reduced expression was significantly related to endometrioid carcinoma, especially the well-differentiated type, compared with AEH and EIN (p?=?0.000 and 0.006, respectively). Ghrelin loss was also related to poorly differentiated histologic grades of endometrioid carcinoma (p?=?0.04). Ghrelin loss is helpful in differentiation between AEH and EIN from endometrioid adenocarcinoma, especially the well-differentiated grade. It could be also related to poor differentiation.     

中介素在人子宫内膜腺癌中的表达及意义

目的检测中介素(Intermedin)在人子宫内膜腺癌组织中的表达,探讨其表达与子宫内膜腺癌临床病理参数以及微血管密度(MVD)的关系。方法应用免疫组化方法检测中介素在子宫内膜单纯性增生、子宫内膜不典型增生和子宫内膜腺癌组织中的表达,通过免疫组化SP法检测组织内微血管密度(MVD),比较中介素表达与肿瘤微血管密度的关系。结果中介素在子宫内膜腺癌中的表达高于子宫内膜单纯性增生及不典型增生中的表达;在子宫内膜腺癌中,中介素的表达与肿瘤的临床FIGO分期呈正相关(P=0.018),与肿瘤的肌层浸润呈正相关(P=0.0004)。中介素的表达与肿瘤的MVD呈正相关(P=0.002)。结论中介素在子宫内膜腺癌的发生发展过程中起到促进作用,并参与肿瘤血管生成。     

Inhibin (10.7 kD prostatic peptide) in normal, hyperplastic, and malignant human endometria: an immunohistochemical study.

The expression of inhibin, a 10.7 kD follicle-stimulating hormone (FSH)-suppressing prostatic peptide of 94 amino acids, was investigated in normal human endometrium, endometrial hyperplasia, and adenocarcinoma, employing the avidin-biotin immunoperoxidase technique. The antiserum used was raised in rabbits against prostatic inhibin isolated from human seminal plasma. The study included 15 well differentiated, 32 moderately differentiated, and 21 poorly differentiated endometrial adenocarcinomas; 26 simple, five complex, and two complex atypical endometrial hyperplasias; and, for comparison, 25 normal proliferative and 30 normal secretory endometria. In malignant and hyperplastic endometrial tissues, inhibin was localized in the epithelial cytoplasm of endometrial glands while the stroma showed weak reactivity. On the other hand, inhibin was undetectable in the early proliferative phase, but was present on the luminal border of the glandular epithelium in the mid- and late proliferative phases. Secretory endometrium displayed strong inhibin reactivity in the cytoplasm of glandular epithelium and in the stroma. The increased inhibin reactivity in secretory endometrium as compared with the proliferative phase is indicative of a functional role for inhibin in the uterus. In addition, its localization in proliferative, hyperplastic, and malignant endometria suggests a possible regulatory role for inhibin in endometrial proliferation and growth.     

转移抑制基因KAI1表达与子宫内膜腺癌进展的关系

目的探讨KAI1蛋白表达与子宫内膜腺癌进展的关系。方法应用免疫组化SP法检测20例正常子宫内膜组织、17例子宫内膜不典型增生和48例子宫内膜腺癌组织中KAI1蛋白的表达情况。结果子宫内膜腺癌中KAI1蛋白的阳性率明显低于正常内膜组织(P<0.01)和内膜不典型增生组织(P<0.01)。KAI1蛋白的表达随子宫内膜腺癌恶性程度(P<0.01),肌层浸润深度(P<0.01)及手术-病理分期(P<0.05)的增高而降低,并与子宫内膜腺癌组织学类型有关(P<0.01),有淋巴结转移的组织中KAI1蛋白阳性率明显低于无转移组织(P<0.01)。KAI1阴性的患者总的生存率低于阳性者(P<0.01,<0.01)。结论KAI1蛋白在子宫内膜腺癌的恶性进展中表达下调,有望成为内膜癌恶性程度评估,转移预测和判断预后的有效指标。     

Demystifying endometrial hyperplasia

The endometrial hyperplasias form a spectrum of proliferative lesions, not all of which conform to conventional definition of hyperplasia. For whilst most hyperplastic lesions are composed of cells normally occurring in the late proliferative phase endometrium, there are those few which consist of genuine atypical cells. Lesions of this type, so-called “atypical endometrial hyperplasias”, tend to merge imperceptibly with well differentiated endometrioid adenocarcinomas, giving rise to major challenges: First and foremost, what are the very essential criteria that should be met before diagnosing such a lesion? And what are the very least that should be insisted upon for diagnosing malignancy once an atypical endometrial hyperplasia has been established? What is its true nature and how should ideally be classified? Other less conflicting, but equally interesting, aspects of endometrial hyperplasia which are covered in this account include the conventional hyperplasias, i.e. those lacking cytological atypia, and the overall incidence, risk factors and treatment of the disease. It is worth noting that “pure” stromal cell proliferations are, in itself, not necessarily neoplastic, for many take the form of endometrial stromal hyperplasia.     

Precursor lesions of endometrial carcinoma: diagnostic approach and molecular pathology

For endometrial adenocarcinoma two precursor lesions are known: endometrioid adenocarcinoma which is the most frequent type 1 carcinoma develops from atypical endometrial hyperplasia whereas endometrial intraepithelial carcinoma (EIC) is the precursor of serous carcinoma and a subset of clear cell carcinoma both representing type 2 carcinomas. Atypical hyperplasia which shows progression rates into carcinoma of up to 40% is challenged by its poor interobserver reproducibility. A better reproducibility is obtained by the endometrial intraepithelial neoplasia (EIN) concept with fewer categories but it is not compatible with the World Health Organization (WHO) classification of endometrial hyperplasia. The EIN concept includes not only the vast majority of the WHO atypical hyperplasia but also approximately half of the complex hyperplasia without atypia. Rarely, atypical hyperplasia is associated with a secretory or mucinous cell type and two thirds of atypical hyperplasia resolve under long-term high dosage progestin therapy. Immunohistochemistry aids in the differential diagnosis of atypical hyperplasia and EIC. Atypical hyperplasia/EIN frequently show PTEN and/or Pax-2 negativity and low Ki-67 and differ from EIC which shows strong diffuse p53 staining and high Ki-67 staining index.     

Expression of multidrug resistance-associated protein in endometrial carcinomas: correlation with clinicopathology and prognosis

The objective of the study reported here was to investigate the expression of multidrug resistance-associated protein (MRP) in endometrial carcinomas and to evaluate the relationship between its expression and clinical data. Using immunohistochemistry, we examined MRP expression in 15 normal endometria, 10 cases of endometrial hyperplasia, and 64 cases of endometrial carcinoma. The normal endometrial glands were weakly immunopositive throughout the menstrual cycle. In addition, we found a progressive increase in the MRP expression of the endometrial hyperplasias. Of the 64 cases of endometrial carcinoma, 62 (97%) expressed MRP. Of these 62 cases, 34 (55%) showed strong immunostaining (>/=50%) and 28 (45%) showed weak immunostaining (<50%). In particular, the intensity of the immunostaining was very strong in 25 (71%) of the 35 grade 1 carcinomas. There was a significant difference in MRP expression between the grade 1 carcinomas and the more poorly differentiated carcinomas (grade 2 or grade 3) (P <.01), especially at stages 1a and 1b (P <.001). However, beyond stage 1c, there was no significant difference in MRP immunoreactivity between the histologic differentiations. Furthermore, beyond stage 1c, those patients with strongly MRP-positive carcinomas had a relatively poorer survival rate than those with weakly MRP-positive carcinomas (P <.05). We concluded that MRP immunoreactivity was already present in normal endometrium and showed a progressive increase from endometrial hyperplasia to well-differentiated carcinoma. Beyond stage 1c, strongly MRP-positive carcinoma indicated a poorer survival rate.