p62 aggregates mediated Caspase 8 activation is responsible for progression of ovarian cancer

Increasing evidence suggests that p62/SQSTM1 functions as a signalling centre in cancer. However, the role of p62 in tumour development depends on the interacting factors it recruits and its precise regulatory mechanism remains unclear. In this study, we investigated the pro‐death signalling recruitment of p62 with the goal of improving anti‐tumour drug effects in ovarian cancer treatment. We found that p62 with Caspase 8 high expression is correlated with longer survival time compared with cases of low Caspase 8 expression in ovarian cancer. In vivo experiments suggested that insoluble p62 and ubiquitinated protein accumulation induced by autophagy impairment promoted the activation of Caspase 8 and increased cell sensitivity to cisplatin. Furthermore, p62 functional domain UBA and LIR mutants regulated autophagic flux and attenuated Caspase 8 activation, which indicates that autophagic degradation is involved in p62‐mediated activation of Caspase 8 in ovarian cancer cells. Collectively, our study demonstrates that p62 promotes Caspase 8 activation through autophagy flux blockage with cisplatin treatment. We have provided evidence that autophagy induction followed by its blockade increases cell sensitivity to chemotherapy which is dependent on p62‐Caspase 8 mediated apoptosis signalling. p62 exhibits pro‐death functions through its interaction with Caspase 8. p62 and Caspase 8 may become novel prognostic biomarkers and oncotargets for ovarian cancer treatment.     

Fine needle aspiration cytology in ovarian lesions: an institutional experience of 584 cases

N. Gupta, A. Rajwanshi, L. K. Dhaliwal, N. Khandelwal, P. Dey, R. Srinivasan and R. Nijhawan
Fine needle aspiration cytology in ovarian lesions: an institutional experience of 584 cases Objective: To assess the diagnostic value of fine needle aspiration cytology (FNAC) in ovarian lesions. Methods: This was a retrospective study of ultrasound‐guided (US) FNAC of 584 ovarian lesions from January 1998 to July 2010. The lesions were categorized into non‐neoplastic lesions, neoplastic lesions and inadequate aspirates. The results were compared with the corresponding histopathology whenever available. Results: Of the 584 lesions, 180 (30.8%) were reported as non‐neoplastic (48 non‐specific inflammation, 11 tuberculosis, 63 functional cysts and 58 endometriotic cysts), 249 (42.6%) as neoplastic (81 benign lesions/tumours and 168 malignant) and 155 (26.5%) as inadequate. Based on the subsequent histopathology, which was available in 121 (20.7%), the cases were divided into those that were concordant and discordant. Concordant cases comprised 92/121 (76%), including 28 non‐neoplastic lesions (seven non‐specific inflammation, nine functional cysts and 12 endometriotic cysts), 42 surface epithelial tumours (13 benign and 29 malignant), 10 germ cell tumours (five mature cystic teratomas and five mixed germ cell tumours), seven sex‐cord stromal tumours (three granulosa cell tumours, one sclerosing stromal tumour, one strümal leutoma, one Sertoli Leydig cell tumour and one malignant Sertoli cell tumour) and five miscellaneous lesions (one plasma cell tumour, two leiomyosarcomas and two cases of necrosis). Discordant cases comprised 29/121 (24%) (21were inconclusive or inadequate on cytology), including four endometriotic cysts, 14 surface epithelial tumours (one cystadenofibroma, one borderline mucinous tumour and 12 carcinomas), five germ cell tumours (two immature teratomas and three mature cystic teratomas), two thecomas, one fibroma, one sclerosing stromal tumour, one fibrosarcoma and one myxoma. FNAC sensitivity for a diagnosis of malignancy was 85.7%, specificity 98.0%, positive predictive value 97.7%, negative predictive value 87.7% and accuracy 92.0%, if 21 inconclusive/inadequate FNACs were excluded; with the latter taken as false negatives, sensitivity was 73.7% and accuracy 76.0%. Conclusion: FNAC has a high specificity for diagnosis of ovarian/adnexal lesions but greater experience is required for the accurate subtyping of neoplasms and sensitivity is limited by inconclusive/inadequate results.     

Cu isotope ratios are meaningful in ovarian cancer diagnosis

BackgroundOvarian cancer diagnosis is currently based on imaging and circulating CA-125 concentrations with well-known limits to sensitivity and specificity. New biomarkers are required to complement CA-125 testing to increase effectiveness. Increases in sensitivity of isotopic separation via multi collector inductively coupled plasma-mass spectrometry have recently allowed highly accurate measurement of copper (Cu) isotopic variations. Studies in breast cancer patients have revealed changes of serum copper isotopic composition demonstrating the potential for development as a cancer biomarker. Evaluating ⁶⁵Cu/⁶³Cu ratios (δ⁶⁵Cu) in serum samples from cancer patients has revealed a strong correlation with cancer development. In this study blood samples from forty-four ovarian cancer patients, and 13 ovarian biopsies were investigated.ResultsHere we demonstrate that changes in Cu isotopes also occurs in ovarian cancer patients. Copper composition determined by multiple collector inductively coupled plasma mass spectrometry revealed that the copper isotopic ratio δ⁶⁵Cu in the plasma of 44 ovarian cancer patient cohort was significantly lower than in a group of 48 healthy donors, and indicated that serum was enriched for ⁶³Cu. Further analysis revealed that the isotopic composition of tumour biopsies was enriched for ⁶⁵Cu compared with adjacent healthy ovarian tissues.ConclusionsWe propose that these changes are due to increase lactate and Cu transporter activities in the tumour. These observations demonstrate that, combined with existing strategies, δ⁶⁵Cu could be developed for use in ovarian cancer early detection.     

A rationale for the clinical development of the thymidylate synthase inhibitor ZD9331 in ovarian and other solid tumours

ZD9331 is an antifolate drug that potently and specifically inhibits thymidylate synthase (TS). In contrast with TS inhibitors such as raltitrexed, it cannot be polyglutamated, leading to antitumour activity independent of folylpolyglutamyl synthetase (FPGS) activity.The growth inhibition IC50 values for ZD9331 and raltitrexed were determined for a panel of 18 human tumour cell lines, that included six colon and six ovarian. The colon lines largely displayed overlapping sensitivities to both drugs with only one of the six lines being drug resistant. In contrast, the ovarian cell lines displayed non-overlapping sensitivities with four being highly resistant to raltitrexed and only one was cross-resistant to ZD9331. Studies were undertaken to explain these results. The colon and ovarian cell lines were characterised for TS activity, and TS and FPGS mRNA expression. TS activity correlated with sensitivity to ZD9331 (r=0.50; p=0.097) and raltitrexed (r=0.74; p=0.0063). Provided the data from the highly drug-resistant cell lines (BE and 41 M) were omitted, TS mRNA expression levels also correlated with ZD9331 (r=0.77; p=0.013) and raltitrexed IC50 (r=0.84; p=0.0031). FPGS mRNA expression correlated with higher sensitivity to raltitrexed relative to ZD9331 (higher ZD9331/raltitrexed IC50 ratios) (r=0.62; p=0.048). Similarly, cell lines with IC50 ratios>median expressed a 1.8-fold higher median level of FPGS mRNA (p=0.0087) compared with those with ratios相似文献   

Secondary follicle growth and oocyte maturation by culture in alginate hydrogel following cryopreservation of the ovary or individual follicles

An option for fertility preservation for women facing a cancer diagnosis involves the cryopreservation of ovarian tissue for later re‐transplantation or in vitro culture, with in vitro culture preferred to avoid reintroduction of the cancer. Small, immature follicles survive the freeze‐thaw process, and can be matured through in follicle maturation (IFM) that involves an initial growth of the follicle and subsequent maturation of the oocyte. The ovarian tissue can be cryopreserved in two forms: (i) cortical strips consisting of follicles and surrounding stroma (Cryo‐Ov) or (ii) individually isolated follicles (Cryo‐In). The aim of this study was to assess the follicle growth and oocyte maturation for follicles that were cryopreserved either as strips or individually using a slow‐freezing cryopreservation method. The two follicle groups, together with non‐cryopreserved control follicles, were grown in an alginate‐based three‐dimensional culture system for 12 days. The overall survival, size increase and antrum formation rates were comparable among the three groups. At day 12 of culture, Androstenedione levels were decreased in the Cryo‐Ov group relative to the other two, and the ratio of progesterone to estradiol was increased in the two cryopreserved groups relative to the control. Both Gja1 (known as connexin 43) and Gja4 (known as connexin 37) mRNA expression were decreased at day 6 in the cryopreserved groups relative to controls, and by day 12, Gja1 was similar for all three groups. Moreover, Cryo‐In resulted in lower GVBD rate indicating some impaired oocyte development. Overall, the present study demonstrated that mouse preantral follicles, either within ovarian tissues or individually isolated, could be successfully cryopreserved by the slow‐freezing method, as evidenced by post‐thaw follicle development and steroidgenesis, oocyte maturation and molecular markers for oocyte and/or granulosa cells connection. Biotechnol. Bioeng. 2009;103: 378–386. © 2009 Wiley Periodicals, Inc.     

THE IMMUNOHISTOCHEMICAL STUDIES OF PROJECTIONS LINKING THE AUDITORY THALAMUS AND NEUROSE- CRETORY HYPOTHALAMUS IN THE BRAIN OF NON - SONGBIRD

应用神经示踪物ＢＤＡ（ｂｉｏｔｉｎｙｌａｔｅｄｄｅｘｔｒａｎａｍｉｎｅ）和免疫组织化学方法对环鸽（ｓｔｒｅｐｔｏｐｅｌｉａｒｉｓｏｒｉａ）丘脑听区和下丘脑内分泌脑区间的神经通路进行了研究。结果发现,丘脑卵形核壳（Ｏｖｓｈｅｌ）及周围区域存在丰富脑啡肽免疫反应神经元。丘脑卵形核尾侧（Ｏｖｐ）有传出纤维直接投射至Ｏｖ壳和下丘脑腹内侧核（ＶＭＮ）。卵形核壳周围和下丘脑内分泌脑区间的传出神经通路显示了丰富的脑啡肽阳性免疫反应细胞和终末标记,在下丘脑腹内侧核中亦存在大量脑腓肽终末标记。结果提示Ｏｖ周围的部分脑啡肽神经元发出的传出纤维可能参与了鸽丘脑听区向内分泌下丘脑区投射的神经通路。     

两种检测抗生素S632A对Vero细胞毒性作用方法的比较

为检测S632A对细胞的毒性作用,比较了CPE法及MTT法检测其效果,结果可见,2种方法均可证明S632A对细胞的毒性较低,MTT法比CPE法敏感性高。     

Onchocerca volvulus: comparative analysis of antibody responses to recombinant antigens in two animal models of onchocerciasis

Experimental infections of chimpanzees with Onchocerca volvulus and cattle with Onchocerca ochengi provide model systems for research in human onchocerciasis. These infections share many similarities from the standpoint of parasite biology, but little is known about the comparability of immune responses in the two systems. To make a direct comparison between the models in terms of immune responsiveness to defined parasite products, three recombinant antigens of O. volvulus (Ov7, Ov103, and B20) were used to analyze the kinetics of antibody production following experimental infection. Each of the antigens was derived from adult cDNA libraries following immunoscreening with sera from chimpanzees (Ov7, Ov103) or cattle (B20). All chimpanzees (n = 12) and cattle (n = 8) displayed responses to Ov7 and Ov103, and all cattle, but only 33% of chimpanzees, showed responses to B20. The dynamics of the response to individual antigens showed further similarities between the chimpanzees and the cattle, with responses to Ov7 and Ov103 peaking after, and B20 before, the onset of patent infections. We conclude that there is good preliminary evidence of concordance in the kinetics of serological responses in the two models. However, individual antigens many be more or less immunogenic in the two systems, making it inadvisable to extrapolate between models concerning the relative immunodominance of specific parasite products.     

Genetic and epigenetic heterogeneity of epithelial ovarian cancer and the clinical implications for molecular targeted therapy

Epithelial ovarian cancer (EOC) is the most lethal gynaecological malignancy, and tumoural heterogeneity (TH) has been blamed for treatment failure. The genomic and epigenomic atlas of EOC varies significantly with tumour histotype, grade, stage, sensitivity to chemotherapy and prognosis. Rapidly accumulating knowledge about the genetic and epigenetic events that control TH in EOC has facilitated the development of molecular‐targeted therapy. Poly (ADP‐ribose) polymerase (PARP) inhibitors, designed to target homologous recombination, are poised to change how breast cancer susceptibility gene (BRCA)‐related ovarian cancer is treated. Epigenetic treatment regimens being tested in clinical or preclinical studies could provide promising novel treatment approaches and hope for improving patient survival.     

ALPHA-FETOPROTEIN-MEDIATED TARGETING—A NEW STRATEGY TO OVERCOME MULTIDRUG RESISTANCE OF TUMOUR CELLSIN VITRO

The possibility of overcoming the multidrug resistance of human malignant cells by using doxorubicin conjugated to alpha-fetoprotein (AFP) was studied. It was shown that this type of antitumour drugs, penetrating the cell by receptor-mediated endocytosis with AFP as a vehicle, raises the sensitivity of the tumour cells that are resistant due to the expression of the multidrug resistance genemdr1. The sensitivity of antibiotic-resistant cell lines SKVLB (a human ovarian carcinoma) and MCF-7 AdrR (a human breast carcinoma) increased by 10- and 4-fold, respectively, when AFP-conjugated doxorubicin was used. The rationale of using human AFP-antitumour drug conjugates for the development of new chemotherapeutic approaches to cancer treatment is discussed.     

Tumour markers and POMB/ACE chemotherapy in the management of ovarian germ cell tumours (GCTs)

The management of ovarian germ cell tumours (GCTs) has changed dramatically over the last 15 years. The combination of the introduction of tumour markers which accurately monitor the behaviour of the majority of germ cell tumours together with the introduction of newer chemotherapeutic agents has meant that few patients even with metastases should succumb from their disease. The tumour markers, human chorionic gonadotrophin (hCG) and alpha-foetoprotein (AFP) and, to a lesser extent, lactate dehydrogenase (LDH) and placental alkaline phosphatase (PLAP) are routinely used in assisting diagnosis, monitoring response to treatment and increasing the sensitivity of follow-up of patients after completing treatment. Analysis of our last 51 patients with all cell types of ovarian germ cell tumour has confirmed the importance of both hCG and AFP in that 45 (88%) of 51 patients had either or both of these tumour markers raised at the start of treatment for metastatic disease. Our data on LDH is incomplete since this has not been a routine assay until 1984 and, of the patients with active disease 10 (48%) had raised LDH at the start of treatment. PLAP has also been measured in a number of patients both on active treatment and in remission. 11 (50%) had raised levels of PLAP at the start of treatment but there was also a false positive rate of 8 (24%) of the 33 patients who were in remission and had not subsequently relapsed.     

In search of specific cytotoxic T lymphocytes infiltrating or accompanying human ovarian carcinoma

Summary Lymphocytes infiltrating human ovarian carcinoma obtained directly from the tumour mass (tumour-infiltrating lymphocytes, TIL) or from the carcinomatous ascites (tumour-associated lymphocytes, TAL) were expanded in vitro in long-term cultures with interleukin-2 and tested for their specific cytolytic activity. Killing of the autologous tumour was detected only in a proportion of the patients, less frequently in TIL compared to TAL. In fact two out of ten TIL and four out of nine TAL cultures tested showed significant levels of lysis against the autologous tumour. This cytotoxic activity was not restricted to the autologous tumour, as other tumour cell lines, including non-ovarian ones, were lysed as well. The cultures that were not cytotoxic against the autologous tumour were in most cases able to lyse other tumour cell lines of ovarian or other histology. Cloning of TIL from one patient was performed: of 22 clones tested, 4 displayed higher cytotoxicity against the autologous tumour compared to the uncloned population and 3 out of these 4 did not kill an irrelevant carcinoma cell line. In order to stimulate the expansion of putative specific effectors we performed mixed lymphocyte/tumour cultures (MLTC) with autologous or allogeneic tumour cells. No stimulation of cytotoxicity against the autologous tumour was detected after MLTC in nine different TAL populations, using autologous or allogeneic tumours as stimulators. On the contrary, peripheral blood lymphocytes from two patients after MLTC with the autologous tumour showed increased killing of the autologous and decreased killing of an allogeneic target. In conclusion TIL and TAL from ovarian carcinoma expanded in vitro with interleukin-2 usually have non-MHC-restricted cytotoxicity and variable degrees of reactivity against the autologous tumour. A preferential killing for the autologous tumour was not observed even after MLTC. These results do not exclude the existence of tumour-specific cytotoxic T lymphocytes in ovarian carcinoma; nevertheless they suggest that putative specific effectors have very low frequency and that culture techniques for expanding their growth more selectively are still to be optimized.     

Molecular Analysis of South African Ovine Herpesvirus 2 Strains Based on Selected Glycoprotein and Tegument Genes

Ovine herpesvirus 2 (OvHV-2), is the causative agent of sheep-associated malignant catarrhal fever (SA-MCF), a generally fatal disease of cattle and other captive wild ruminants. Information on the OvHV-2 strains circulating in South Africa (SA) and other African countries with regard to genetic structure and diversity, and pattern of distribution is not available. This study aimed to characterize the OvHV-2 strains circulating in SA using selected genes encoding glycoproteins and tegument proteins. To establish the genetic diversity of OvHV-2 strains, four genes, Ov 7, Ov 8 ex2, ORF 27 and ORF 73 were selected for analysis by PCR and DNA sequencing. Nucleotide and amino acid multiple sequence analyses revealed two genotypes for ORF 27 and ORF 73, and three genotypes for Ov 7 and Ov 8 ex2, randomly distributed throughout the regions. Ov 7 and ORF 27 nucleotide sequence analysis revealed variations that distinguished SA genotypes from those of reference OvHV-2 strains. Epitope mapping analysis showed that mutations identified from the investigated genes are not likely to affect the functions of the gene products, particularly those responsible for antibody binding activities associated with B-cell epitopes. Knowledge of the extent of genetic diversity existing among OvHV-2 strains has provided an understanding on the distribution patterns of OvHV-2 strains or genotypes across the regions of South Africa. This can facilitate the management of SA-MCF in SA, in terms of introduction of control measures or safe practices to monitor and control OvHV-2 infection. The products encoded by the Ov 7, Ov 8 ex2 and ORF 27 genes are recommended for evaluation of their coded proteins as possible antigens in the development of an OvHV-2 specific serodiagnostic assay.     

Localisation and expression of aquaporin subtypes in epithelial ovarian tumours

To characterise AQP subtype localisation and expression in epithelial ovarian tumours, immunohistochemistry was used to assess the localisation and expression of AQP1-9 in 30 benign tumour cases, 30 borderline tumour cases, 50 malignant tumour cases and 20 normal ovarian tissue cases. Multiple AQP subtypes were expressed in epithelial ovarian tumours, with each AQP subtype displaying a different pattern of localisation and expression. AQP1 was mainly expressed in the microvascular endothelium, and AQP 2-9 were mainly expressed in tumour cells. Most AQP subtypes co-localised in the basolateral membranes of the epithelia of benign tumours and plasma membranes of malignant tumour cells. The positive rates for AQP1, 5, 6, 7, 8, and 9 were over 50%, but those for AQP2, 3 and 4 were only 10-40%. The expression of AQP1, 5 and 9 in malignant and borderline tumours was significantly higher than that in benign tumours (P<0.05) and normal ovarian tissue (P<0.05). However, AQP6 expression in ovarian malignant and borderline tumours was significantly lower than that in benign tumours (P<0.01) or normal ovarian tissue (P<0.01). AQP1 expression was increased in cases with ascites volumes greater than 1000 mL (P<0.05), AQP5 expression was greater in cases with lymph node metastasis (P<0.05), and more AQP9 expression was observed in G3 cases versus G1 and G2 cases (P<0.01). These results suggest that changes in the distribution and expression of AQP subtypes may be involved in ovarian carcinogenesis. This study presents a novel avenue of research that could illuminate the mechanism of ovarian carcinogenesis and treatment.     

Primary Ovarian Carcinomas and Abdominal Metastasis Contain 4,6-Disulfated Chondroitin Sulfate Rich Regions,Which Provide Adhesive Properties to Tumour Cells

High mortality in ovarian cancer patients is primarily caused through rapid metastasis of the tumour, but the underlying mechanisms are poorly understood. Glycosaminoglycans, are abundantly present in tumours and chondroitin sulfate-E (CSE), a highly 4,6-sulfated glycosaminoglycan, has been indicated to play a role in carcinogenesis. In this study we investigated the presence of CSE in ovarian cancer metastasis and studied its role in tumour cell adhesiveness and migration. CSE was studied immunohistochemically in primary ovarian carcinomas and abdominal metastases using the single chain antibody GD3G7. The role of CSE was studied in 2D (scratch assays) and 3D (collagen matrices, spheroids) systems using SKOV3 cells applying 1: overexpression of CSE by stable transfection with DNA encoding GalNAc4S-6 sulfotransferase, 2: enzymatic removal of CS, and 3: addition of CSE. In ovarian cancer tissue, CSE expression was predominantly seen in the stromal compartment of both primary ovarian carcinomas and metastases, with a comparable degree of intensity and extent. Overexpression of CSE disaccharide units by tumour cells increased their adhesive properties which was especially seen in tumour spheroid formation. Increased expression of CSE reduced cell migration. Addition of free CSE had similar effects. The data presented here indicate that CSE is associated with metastatic lesions and that it provides tumours with adhesive properties. CSE rich motifs are put forward as a potential target for ovarian cancer therapy.     

A novel carbohydrate antigen expression during development of Opisthorchis viverrini- associated cholangiocarcinoma in golden hamster: a potential marker for early diagnosis

Poor prognosis of cholangiocarcinoma (CCA) is primarily due to delayed diagnosis because of the lack of appropriate tumor marker(s) to detect cancer development at an early stage. We have recently established a S121 monoclonal antibody (mAb) which recognizes an unidentified glycan epitope on MUC5AC, designated as CCA-associated carbohydrate antigen (CCA-CA). This antigen is expressed in human CCA cells but not in normal biliary epithelia. Detection of CCA-CA effectively distinguished CCA patients' sera from normal control sera with high specificity and sensitivity. In the present study, we examined a time profile of the expression of CCA-CA by immunohistochemical methods in the liver tissues of Opisthorchis viverrini (Ov)-associated CCA in a hamster model. Hamsters were divided into four groups; non-treated, Ov infected, NDMA (N-nitrosodimethamine) treated and Ov + NDMA treated groups, and animals from each group were euthanized at 1, 3 and 6 months post-treatment. CCA-CA was not detected in normal biliary cells of non-treated hamsters throughout the course of experiment. CCA-CA became detectable in the cytoplasm and apical surface of biliary cells of the NDMA and Ov + NDMA groups at early stage (1 month) of tumor development and increased with tumor progression. In contrast, CCA-CA was detected as nuclear staining at the 1 month post Ov infection and declined thereafter. These results suggest the possibility of CCA-CA as an early marker for CCA.     

Androgen receptor gene methylation and exon one CAG repeat length in ovarian cancer: differences from breast cancer

More than one neoplastic founder clone can exist in benign epithelial tumours. Although theories of clonal selection make pluriclonality appear unlikely in carcinomas, published data do not exclude this possibility. This study looked for evidence of multiclonal X inactivation in ovarian carcinoma using AR methylation as a marker. Fifteen unifocal ovarian carcinomas and 14 multifocal carcinomas all in Scottish patients were studied. One representative formalin-fixed paraffin-embedded tumour block was chosen for each of the former and two for the latter. From each of these 43 tumour blocks three samples each of approximately 10(4) carcinoma cells were obtained by microdissection (129 in all). DNA released by proteinase K digestion was subjected to PCR amplification of the androgen receptor gene AR exon I CAG repeat polymorphism with and without prior digestion with methylation-sensitive restriction enzymes HpaII and HhaI. Complex amplification patterns were consistent with mosaic X inactivation in some ovarian carcinomas but acquired anomalies of AR methylation cannot be excluded. Parallel analysis of other X-linked polymorphic loci would strengthen the inference of clonality status from DNA methylation data in tumour X studies. Strikingly, the number of CAG repeats in the 29 ovarian tumour patients (median 16, range 11 - 20) was substantially fewer than in 34 previously studied breast cancer patients from the same scottish population (median 21, range 14 - 26; P < 0.0001), and women homozygous for the AR CAG repeat were over-represented in the ovarian cancer patients but not in the breast cancer series. These findings reinforce recent suggestions that AR may have a role in ovarian carcinogenesis.     

Immunohistochemical analysis of DNA 'mismatch-repair' enzyme human Mut-S-Homologon-2 in ovarian carcinomas

The human Mut-S-Homologon-2 (hMSH-2) gene product is a member of a highly conserved family of proteins involved in postreplication mismatch repair. We have analysed hMSH-2 expression in normal ovarian tissue (n=15) and ovarian carcinomas (n=40). hMSH-2 protein was investigated immunohistochemically on frozen sections using a highly sensitive streptavidin–peroxidase technique and a specific mouse monoclonal antibody (clone FE11). A hMSH-2-immunoreactivity score (hMSH-2-IRS) for semiquantitative analysis of hMSH-2 expression is presented. In normal ovarian tissue, we only found weak nuclear immunoreactivity for hMSH-2 in 60%, while the remaining 40% were hMSH-2 negative (mean hMSH-2-IRS: 0.73; SD: ±0.70). All ovarian carcinomas analysed revealed moderate to strong nuclear immunoreactivity (mean hMSH-2-IRS: 8.05; SD: ±3.65). hMSH-2 staining was heterogeneous, with visual differences between individual tumour cells. Expression of hMSH-2 protein was consistently and strongly upregulated in tumour cells of ovarian carcinomas as compared to normal ovarian tissue. No statistically significant correlation in comparing the labelling patterns for hMSH-2 with the labelling patterns for Ki-67 (mean percentage of Ki-67 positive tumour cells: 25.88%; SD: ±18.43) was observed in ovarian carcinomas. Furthermore, no statistical significant correlations between hMSH-2-IRS and histological grading (p=0.47), histological type of carcinoma (p=0.706) or FIGO-classification (p=0.054) were found. Our findings indicate that (a) hMSH-2 is expressed in normal human ovarian tissue, (b) expression of hMSH-2 is increased in ovarian carcinomas, (c) expression of hMSH-2 may be of importance for the genetic stability of ovarian carcinomas in vivo, (d) hMSH-2 mutations may not cause microsatellite instability in ovarian carcinomas, (e) hMSH-2 may contribute to mechanisms responsible for resistance to anticancer drugs.