Proteomic Comparison of Malignant Human Germ Cell Tumor Cell Lines.

Malignant germ cell tumors (GCT) are the most common malignant tumors in young men between 18 and 40 years. The correct identification of histological subtypes, in difficult cases supported by immunohistochemistry, is essential for therapeutic management. Furthermore, biomarkers may help to understand pathophysiological processes in these tumor types. Two GCT cell lines, TCam-2 with seminoma-like characteristics, and NTERA-2, an embryonal carcinoma-like cell line, were compared by a quantitative proteomic approach using high-resolution mass spectrometry (MS) in combination with stable isotope labelling by amino acid in cell culture (SILAC). We were able to identify 4856 proteins and quantify the expression of 3936. 347 were significantly differentially expressed between the two cell lines. For further validation, CD81, CBX-3, PHF6, and ENSA were analyzed by western blot analysis. The results confirmed the MS results. Immunohistochemical analysis on 59 formalin-fixed and paraffin-embedded (FFPE) normal and GCT tissue samples (normal testis, GCNIS, seminomas, and embryonal carcinomas) of these proteins demonstrated the ability to distinguish different GCT subtypes, especially seminomas and embryonal carcinomas. In addition, siRNA-mediated knockdown of these proteins resulted in an antiproliferative effect in TCam-2, NTERA-2, and an additional embryonal carcinoma-like cell line, NCCIT. In summary, this study represents a proteomic resource for the discrimination of malignant germ cell tumor subtypes and the observed antiproliferative effect after knockdown of selected proteins paves the way for the identification of new potential drug targets.

Primary signet-ring stromal tumour of the testis: case report with literature review.

Primary signet-ring stromal tumour of the testis (PSRSTT) is a very rare type of primary testicular tumour, which is not actually mentioned in the current WHO categorization of tumours of the male genital organs. In this case we report about histologically and immunohistochemically features of this rare tumour. In the present case, PSRTT was found in the orchiectomy preparation of a 69-year-old man with painless swelling of his left testicle. The tumour was well circumscribed and separated from the normal testicular tissue by a fibrous capsule. The tumour cells showed a signet-ring pattern and were separated by thin collagen bundles. No mitotic activity and necrosis were found inside the tumour. Immunohistochemically, the tumour was positive for vimentin, neuron-specific enolase (NSE), S-100 protein, ß-catenin and cyclin D1. No expression of cytokeratin, actin, SALL4, OCT3/4, and especially, inhibin and calretinin were detected. In conclusion, the presence of signet-ring cell formation can be found in different tumours of the testis. PSRSTT is a rare tumour that needs to be considered, in particular, to distinct them from other tumours with signet-ring cell pattern.

Testosterone metabolites inhibit proliferation of castration- and therapy-resistant prostate cancer.

Novel treatments for castration-resistant prostate cancer (CRPC) such as abiraterone acetate (AA) or enzalutamide effectively target the androgen pathway to arrest aberrant signalling and cell proliferation. Testosterone is able to inhibit tumour cell growth in CRPC. Estrogen receptor-beta (ERß) binds the testosterone-metabolites 3ß-androstanediol and 3α-androstanediol in parallel to the canonical estradiol. In the prostate it is widely accepted that ERß regulates estrogen signalling, mediating anti-proliferative effects. We used the prostate cancer cell lines LNCaP, PC-3, VCaP, and the non-neoplastic BPH-1. VCaP cells were treated with 1 nmol/L testosterone over 20 passages, yielding the cell line VCaPrev, sensitive to hormone therapies. In contrast, LNCaP cells were grown for more than 100 passages yielding a high passage therapy resistant cell line (hiPLNCaP). VCaP and hiPLNCaP cell lines were treated with 5 µmol/L AA for more than 20 passages, respectively, generating the AA-tolerant-subtypes VCaPAA and hiPLNCaPAA. Cell lines were treated with testosterone, dihydrotestosterone (DHT), R1881, and the androgen-metabolites 3ß-androstanediol and 3α-androstanediol. 3ß-androstanediol or 3α-androstanediol significantly reduced proliferation in all cell lines except the BPH-1 and androgen receptor-negative PC-3 and markedly downregulated AR and estrogen receptor alpha (ERα). Whereas ERß expression was increased in all cell lines except BPH-1 or PC-3. In summary, 3ß-adiol or 3α-adiol, as well as DHT and R1881, significantly reduced tumour cell growth in CRPC cells. Thus, these compounds represent novel potential therapeutic approaches to overcome drug-resistance in CRPC, especially with regard to AR-V7 function in therapy resistance. Furthermore, these data confirm the tumour suppressor properties of ERß in CRPC.

Pathogenic and targetable genetic alterations in 70 urachal adenocarcinomas.

Urachal cancer (UrC) is a rare but aggressive malignancy often diagnosed in advanced stages requiring systemic treatment. Although cytotoxic chemotherapy is of limited effectiveness, prospective clinical studies can hardly be conducted. Targeted therapeutic treatment approaches and potentially immunotherapy based on a biological rationale may provide an alternative strategy. We therefore subjected 70 urachal adenocarcinomas to targeted next-generation sequencing, conducted in situ and immunohistochemical analyses (including PD-L1 and DNA mismatch repair proteins [MMR]) and evaluated the microsatellite instability (MSI) status. The analytical findings were correlated with clinicopathological and outcome data and Kaplan-Meier and univariable/multivariable Cox regression analyses were performed. The patients had a mean age of 50 years, 66% were male and a 5-year overall survival (OS) of 58% and recurrence-free survival (RFS) of 45% was detected. Sequence variations were observed in TP53 (66%), KRAS (21%), BRAF (4%), PIK3CA (4%), FGFR1 (1%), MET (1%), NRAS (1%), and PDGFRA (1%). Gene amplifications were found in EGFR (5%), ERBB2 (2%), and MET (2%). We detected no evidence of MMR-deficiency (MMR-d)/MSI-high (MSI-h), whereas 10 of 63 cases (16%) expressed PD-L1. Therefore, anti-PD-1/PD-L1 immunotherapy approaches might be tested in UrC. Importantly, we found aberrations in intracellular signal transduction pathways (RAS/RAF/PI3K) in 31% of UrCs with potential implications for anti-EGFR therapy. Less frequent potentially actionable genetic alterations were additionally detected in ERBB2 (HER2), MET, FGFR1, and PDGFRA. The molecular profile strengthens the notion that UrC is a distinct entity on the genomic level with closer resemblance to colorectal than to bladder cancer.

Role of N-cadherin in proliferation, migration, and invasion of germ cell tumours.

Germ cell tumors (GCTs) are the most common malignancies in young men. Most patients with GCT can be cured with cisplatin-based combination chemotherapy, even in metastatic disease. In case of therapy resistance, prognosis is usually poor. We investigated the potential of N-cadherin inhibition as a therapeutic strategy. We analyzed the GCT cell lines NCCIT, NTERA-2, TCam-2, and the cisplatin-resistant sublines NCCIT-R and NTERA-2R. Effects of a blocking antibody or siRNA against N-cadherin on proliferation, migration, and invasion were investigated. Mouse xenografts of GCT cell lines were analyzed by immunohistochemistry for N-cadherin expression. All investigated GCT cell lines were found to express N-cadherin protein in vitro and in vivo. Downregulation of N-cadherin in vitro leads to a significant inhibition of proliferation, migration, and invasion. N-cadherin-downregulation leads to a significantly higher level of pERK. N-cadherin-inhibition resulted in significantly higher rates of apoptotic cells in caspase-3 staining. Expression of N-cadherin is preserved in cisplatin-resistant GCT cells, pointing to an important physiological role in cell survival. N-cadherin-downregulation results in a significant decrease of proliferation, migration, and invasion and stimulates apoptosis in cisplatin-naive and resistant GCT cell lines. Therefore, targeting N-cadherin may be a promising therapeutic approach, particularly in cisplatin-resistant, therapy refractory and metastatic GCT.

Differential expression of Mediator complex subunit MED15 in testicular germ cell tumors.

BACKGROUND: Testicular germ cell tumors (TGCT) are the most common cancer entities in young men with increasing incidence observed in the last decades. For therapeutic management it is important, that TGCT are divided into several histological subtypes. MED15 is part of the multiprotein Mediator complex which presents an integrative hub for transcriptional regulation and is known to be deregulated in several malignancies, such as prostate cancer and bladder cancer role, whereas the role of the Mediator complex in TGCT has not been investigated so far. Aim of the study was to investigate the implication of MED15 in TGCT development and its stratification into histological subtypes. METHODS: Immunohistochemical staining (IHC) against Mediator complex subunit MED15 was conducted on a TGCT cohort containing tumor-free testis (n = 35), intratubular germ cell neoplasia unclassified (IGCNU, n = 14), seminomas (SEM, n = 107) and non-seminomatous germ cell tumors (NSGCT, n = 42), further subdivided into embryonic carcinomas (EC, n = 30), yolk sac tumors (YST, n = 5), chorionic carcinomas (CC, n = 5) and teratomas (TER, n = 2). Quantification of MED15 protein expression was performed through IHC followed by semi-quantitative image analysis using the Definiens software. RESULTS: In tumor-free seminiferous tubules, MED15 protein expression was absent or only low expressed in spermatogonia. Interestingly, the precursor lesions IGCNU exhibited heterogeneous but partly very strong MED15 expression. SEM weakly express the Mediator complex subunit MED15, whereas NSGCT and especially EC show significantly enhanced expression compared to tumor-free testis. CONCLUSIONS: In conclusion, MED15 is differentially expressed in tumor-free testis and TGCT. While MED15 is absent or low in tumor-free testis and SEM, NSGCT highly express MED15, hinting at the diagnostic potential of this marker to distinguish between SEM and NSGCT. Further, the precursor lesion IGCNU showed increased nuclear MED15 expression in the preinvasive precursor cells, which may provide diagnostic value to distinguish between benign and pre-malignant testicular specimen, and may indicate a role for MED15 in carcinogenesis in TGCT.

Ovarian-type epithelial tumours of the testis: immunohistochemical and molecular analysis of two serous borderline tumours of the testis.

Tumours of ovarian-epithelial type of the testis, including serous borderline tumours, represent very rare entities. They are identical to the surface epithelial tumours of the ovary and have been reported in patients from 14 to 68 years of age. We describe two cases of a 46- and a 39-year old man with incidental findings of intratesticular masses of the left respectively right testis. Under the assumption of a malignant testicular tumour the patients were subjected to inguinal orchiectomy. Histologically, the tumours were identical to their ovarian counterparts: They showed a cystic configuration with a fibrous wall and irregular papillary structures lined by partially multistratified columnar cells and areas of hobnail cells. Furthermore, there was mild cytological atypia with a proliferative activity of below 5% as proved by Ki67 staining; mitoses could not be detected. Immunohistochemically, the tumour cells displayed expression of pan-cytokeratin AE3, progesterone receptor, Wilms' tumour protein (WT1), and PAX8 (Paired box gene 8). Estrogen receptor was expressed in one case. Octamer-binding transcription factor-4 (OCT4), calretinin, thrombomodulin, and D2-40 were not expressed. Mutation testing of BRAF revealed a BRAF V600E mutation in one case, while testing for KRAS mutations proved to be negative in both. The BRAF mutated tumour showed strong cytosolic and membranous positivity for B-Raf also on immunohistochemical analysis. Comparative genomic hybridization of one case could not reveal any chromosomal aberrations.

CK19 is a sensitive marker for yolk sac tumours of the testis.

BACKGROUND: Malignant germ cell tumours are the most common malignant tumours in young men. They are histologically divided into seminomas and non-seminomas. Non-seminomas are further subdivided into embryonic carcinomas, yolk sac tumours, chorionic carcinomas, and teratomas. For the therapeutic management it is essential to differentiate between these histological subtypes. METHODS: Investigated cases included normal testis (n = 50), intratubular germ cell neoplasia (n = 25), seminomas (n = 67), embryonic carcinomas (n = 56), yolk sac tumours (n = 29), chorionic carcinomas (n = 2), teratomas (n = 7) and four metastases of YST's for their CK19 expression. In addition Leydig cell- (n = 10) and Sertoli cell- tumours (n = 4) were included in this study. RESULTS: All investigated seminomas, embryonic carcinomas as well as normal testis and intratubular germ cell neoplasias did not express CK19. In contrast, all investigated yolk sac tumours strongly expressed CK19 protein. These findings became also evident in mixed germ cell tumours consisting of embryonic carcinomas and yolk sac tumours, although CK19-expression could also be observed in analysed chorionic carcinomas and epithelial components of teratomas. CONCLUSION: CK19 proved to be a sensitive marker to identify yolk sac tumours of the testis and to distinguish them from other germ cell tumours, especially seminomas and embryonic carcinomas. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/4075546891400979.

Tumor-associated macrophages are involved in tumor progression in papillary renal cell carcinoma.

Tumor-associated macrophages (TAMs) play a key role in cancer development. Especially, the immunosuppressive M2 phenotype is associated with increased tumor growth, invasiveness and metastasis. The differentiation of macrophages to the alternative phenotype M2 is mediated, inter alia, by macrophage colony-stimulating factor (M-CSF). Papillary renal cell carcinoma (RCC) represents a rare tumor type which, based upon histological criteria, can be subdivided into two subtypes (I and II), of which type II is associated with poor prognosis. In both subtypes, typically, a dense infiltrate of macrophages is found. In the present study, the expression of CD68, CD163, M-CSF, Ki-67, and CD31 was examined in 30 type I and 30 type II papillary RCCs (n = 60). Both types of papillary RCCs contained an equally dense infiltrate of CD68-positive macrophages. Nearly all macrophages in papillary RCC type II expressed CD163, a characteristic for M2 macrophages. In type I papillary RCC, less than 30 % of macrophages expressed CD163. Furthermore, tumor cells in type II papillary RCC expressed significantly more M-CSF and showed increased (Ki-67 expression defined) proliferative activity in comparison with type I papillary RCC. In addition, the (CD31 defined) capillary density was higher in type II than in type I papillary RCC. A dense infiltrate of M2 phenotype TAM and high M-CSF expression in tumor cells are key features of type II papillary RCC. These findings might explain why the prognosis of papillary RCC type II is worse than that of type I.

Phytoestrogens regulate the proliferation and expression of stem cell factors in cell lines of malignant testicular germ cell tumors.

Phytoestrogens have been shown to exert anti-proliferative effects on different cancer cells. In addition it could be demonstrated that inhibition of proliferation is associated with downregulation of the known stem cell factors NANOG, POU5F1 and SOX2 in tumor cells. We demonstrate the potential of Belamcanda chinensis extract (BCE) and tectorigenin as anticancer drugs in cell lines of malignant testicular germ cell tumor cells (TGCT) by inhibition of proliferation and regulating the expression of stem cell factors. The TGCT cell lines TCam-2 and NTera-2 were treated with BCE or tectorigenin and MTT assay was used to measure the proliferation of tumor cells. In addition, the expression of stem cell factors was analyzed by quantitative PCR and western blot analysis. Furthermore, global expression analysis was performed by microarray technique. BCE and tectorigenin inhibited proliferation and downregulated the stem cell factors NANOG and POU5F1 in TGCT cells. In addition, gene expression profiling revealed induction of genes important for the differentiation and inhibition of oncogenes. Utilizing connectivity map in an attempt to elucidate mechanism underlying BCE treatments we found highly positive association to histone deacetylase inhibitors (HDACi) amongst others. Causing no histone deacetylase inhibition, the effects of BCE on proliferation and stem cell factors may be based on histone-independent mechanisms such as direct hyperacetylation of transcription factors. Based on these findings, phytoestrogens may be useful as new agents in the treatment of TGCT.

13-year-old tuberous sclerosis patient with renal cell carcinoma associated with multiple renal angiomyolipomas developing multifocal micronodular pneumocyte hyperplasia.

BACKGROUND: The autosomal dominant tumor syndrome tuberous sclerosis complex is caused by the mutated TSC1 gene, hamartin, and the TSC2 gene, tuberin. Patients with this complex develop typical cutaneus symptoms such as peau chagrin or angiofibromas of the skin as well as other lesions such as astrocytomas in the brain and lymphangioleiomyomatosis in the lung. Only a few tuberous sclerosis patients have been described who showed a multifocal micronodular pneumocyte hyperplasia of the lung. Another benign tumor which often occurs together with tuberous sclerosis is the angiomyolipoma of the kidney. Furthermore, an increased incidence of renal cell carcinoma in connection with tuberous sclerosis has also been proven. CASE PRESENTATION: We report a 13-year-old white girl with epilepsy and hypopigmented skin lesions. Radiological studies demonstrated the typical cortical tubers leading to the diagnosis of tuberous sclerosis. In the following examinations a large number of angiomyolipomas were found in both kidneys. One lesion showed an increasing size and tumor like aspects in magnetic resonance imaging. The pathological examination of the following tumorectomy demonstrated an unclassified renal cell carcinoma. Four months postoperatively, a follow-up computer tomography revealed multiple bilateral pulmonary nodules. To exclude lung metastases of the renal cell carcinoma, multiple open-lung biopsies were performed. CONCLUSION: Here we report a diagnostically challenging case of a 13-year-old patient with tuberous sclerosis and angiomyolipomas of the kidney who developed an unclassified renal cell carcinoma as well as multifocal micronodular pneumocyte hyperplasia.

Sertoliform cystadenoma: a rare benign tumour of the rete testis.

Sertoliform cystadenoma of the rete testis represents an uncommon benign tumour. They appear in patients from 26 to 62 years of age. We describe a case of a 66-year-old man with a tumour in the area of the epididymal head. The tumour markers were not increased. Under the assumption of a malignant testicular tumour an inguinal orchiectomy was performed. The cut surface of this tumour was of grey/white color and showed small cysts. The tumour consisted of two compartments. The epithelial like tumour cells showed a sertoliform growth pattern and cystic dilatations. In between the tumour cells repeatedly actin expressing sclerotic areas could be recognized as the second tumour component. Proliferative activity was not increased. Immunohistochemically the tumour cells were positiv for inhibin, S-100, and CD 99. Alpha feto protein (AFP), human chorionic gonadotropin (ß-HCG) and placental alkaline phosphatase (PLAP) as well as synaptophysin, epithelial membrane antigene (EMA), and BCL-2 were not expressed. As far as we know this is the sixth reported case of this tumour. Because of the benign nature of this tumour the correct diagnosis is important for the intra- and postoperative management. Here we present a case of this rare tumour and discuss potential differential diagnosis. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1956026143857335.

N-cadherin expression in malignant germ cell tumours of the testis.

BACKGROUND: Testicular germ cell tumours (TGCTs) are the most common malignancy in young men aged 18-35 years. They are clinically and histologically subdivided into seminomas and non-seminomas. Cadherins are calcium-dependent transmembrane proteins of the group of adhesion proteins. They play a role in the stabilization of cell-cell contacts, the embryonic morphogenesis, in the maintenance of cell polarity and signal transduction. N-cadherin (CDH2), the neuronal cadherin, stimulates cell-cell contacts during migration and invasion of cells and is able to suppress tumour cell growth. METHODS: Tumour tissues were acquired from 113 male patients and investigated by immunohistochemistry, as were the three TGCT cell lines NCCIT, NTERA-2 and Tcam2. A monoclonal antibody against N-cadherin was used. RESULTS: Tumour-free testis and intratubular germ cell neoplasias (unclassified) (IGCNU) strongly expressed N-cadherin within the cytoplasm. In all seminomas investigated, N-cadherin expression displayed a membrane-bound location. In addition, the teratomas and yolk sac tumours investigated also differentially expressed N-cadherin. In contrast, no N-cadherin could be detected in any of the embryonal carcinomas and chorionic carcinomas examined. This expression pattern was also seen in the investigated mixed tumours consisting of seminomas, teratomas, and embryonal carcinoma. CONCLUSIONS: N-cadherin expression can be used to differentiate embryonal carcinomas and chorionic carcinomas from other histological subtypes of TGCT.

N-cadherin is differentially expressed in histological subtypes of papillary renal cell carcinoma.

BACKGROUND: Papillary renal cell carcinoma (RCC) represents a rare tumor, which is divided, based on histological criteria, into two subtypes. In contrast to type I papillary RCC type II papillary RCC shows a worse prognosis. So far, reliable immunohistochemical markers for the distinction of these subtypes are not available. METHODS: In the present study the expression of N(neural)-, E(epithelial)-, P(placental)-, and KSP(kidney specific)-cadherin was examined in 22 papillary RCC of histological type I and 18 papillary RCC of histological type II (n = 40). RESULTS: All papillary RCC type II displayed a membranous expression for N-cadherin, whereas type I did not show any membranous positivity for N-cadherin. E-cadherin exhibited a stronger, but not significant, membranous as well as cytoplasmic expression in type II than in type I papillary RCC. A diagnostic relevant expression of P- and KSP-cadherin could not be demonstrated in both tumor entities. CONCLUSION: Thus N-cadherin represents the first immunhistochemical marker for a clear cut differentiation between papillary RCC type I and type II and could be a target for therapy and diagnostic in the future. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2011556982761733.

Pleural malakoplakia caused by Rhodococcus equi infection in a patient after stem cell transplantation.

Malakoplakia is a disease especially of the urinary tract with typical plaques most frequently observed in the urinary bladder's mucosa. In the context of immunosuppression malakoplakia can also occur in other organs. Some of these extravesical malakoplakias are associated with an infection by Rhodococcus equi, a rare human pathogen well known from veterinary medicine. Here we present the first case of a pleural malakoplakia without lung involvement caused by a proved Rhodococcus equi infection.

Chemokine-mediated distribution of dendritic cell subsets in renal cell carcinoma.

BACKGROUND: Renal cell carcinoma (RCC) represents one of the most immunoresponsive cancers. Antigen-specific vaccination with dendritic cells (DCs) in patients with metastatic RCC has been shown to induce cytotoxic T-cell responses associated with objective clinical responses. Thus, clinical trials utilizing DCs for immunotherapy of advanced RCCs appear to be promising; however, detailed analyses concerning the distribution and function of DC subsets in RCCs are lacking. METHODS: We characterized the distribution of the different immature and mature myeloid DC subsets in RCC tumour tissue and the corresponding normal kidney tissues. In further analyses, the expression of various chemokines and chemokine receptors controlling the migration of DC subsets was investigated. RESULTS: The highest numbers of immature CD1a+ DCs were found within RCC tumour tissue. In contrast, the accumulation of mature CD83+/DC-LAMP+ DCs were restricted to the invasive margin of the RCCs. The mature DCs formed clusters with proliferating T-cells. Furthermore, a close association was observed between MIP-3α-producing tumour cells and immature CCR6+ DC recruitment to the tumour bed. Conversely, MIP-3ß and SLC expression was only detected at the tumour border, where CCR7-expressing T-cells and mature DCs formed clusters. CONCLUSION: Increased numbers of immature DCs were observed within the tumour tissue of RCCs, whereas mature DCs were found in increased numbers at the tumour margin. Our results strongly implicate that the distribution of DC subsets is controlled by local lymphoid chemokine expression. Thus, increased expression of MIP-3α favours recruitment of immature DCs to the tumour bed, whereas de novo local expression of SLC and MIP-3ß induces accumulation of mature DCs at the tumour margin forming clusters with proliferating T-cells reflecting a local anti-tumour immune response.

Stem-cell protein Piwil2 is widely expressed in tumors and inhibits apoptosis through activation of Stat3/Bcl-XL pathway.

The genes of the piwi family are defined by conserved PAZ and Piwi domains and play important roles in stem-cell self-renewal, RNA silencing and translational regulation in various organisms. Both, mouse and human Piwil2 genes, members of the piwi gene family, are specifically expressed in testis. We report here enhanced expression of the human Piwil2 gene in testicular seminomas, but not in testicular non-seminomatous tumors. Expression of the Piwil2 gene was also found in different tumors examined, including prostate, breast, gastrointestinal, ovarian and endometrial cancer of human and in breast tumors, rhabdomyosarcoma and medulloblastoma of mouse. Therefore, Piwil2 can be categorized as a novel member of cancer/testis antigens. To identify genes activated by Piwil2, RNA isolated from NIH-3T3 cells expressing constitutively Piwil2 were compared with RNA samples from control NIH-3T3 cells using a cancer gene array. Induction of high-level expression of the antiapoptotic gene Bcl-X(L) was observed in cells expressing Piwil2. Furthermore, increased Bcl-X(L) expression correlated with increase of signal transducer and activator of transcription 3 (Stat3) expression. Gene silencing of Piwil2 with its small interference RNA suppressed Stat3 and Bcl-X(L) expression and induced apoptosis. A causal link between Piwil2 expression and inhibition of apoptosis and enhanced proliferation was demonstrated in cells expressing Piwil2. Furthermore, results of soft agar assay indicated that Piwil2 overexpression induced transformation of fibroblast cells. In summary, our results demonstrate that Piwil2 is widely expressed in tumors and acts as an oncogene by inhibition of apoptosis and promotion of proliferation via Stat3/Bcl-X(L) signaling pathway. Expression of Piwil2 in a wide variety of tumors could be a useful prognostic factor that could have also diagnostic and therapeutic implications.

The balance between MMP-2/-9 and TIMP-1/-2 is shifted towards MMP in renal cell carcinomas and can be further disturbed by hydrogen peroxide.

In malignant tumors the balance of matrix metalloproteinases (MMP) and tissue inhibitors of matrix metalloproteinases (TIMP) is disturbed. Radical oxygen species (ROS) and hydrogen peroxide potentially influence this balance. Therefore, we analyzed the balance of MMP and TIMP in renal cell carcinoma (RCC) specimens and cell lines. In RCC specimens MMP-2, MMP-9, TIMP-1, and TIMP-2 were immunohistochemically detected. Tumor-associated macrophages (TAM) as a potential source of ROS were characterized with an anti-CD68 antibody. Three RCC cell lines were treated with sublethal concentrations of hydrogen peroxide to simulate the effects of radical oxygen species. MMP-2 and MMP-9 protein expression was measured by zymography. mRNA expression of MMP-2, MMP-9, TIMP-1, and TIMP-2 was assessed by quantitative reverse transcriptase polymerase chain reaction. Tumor cell-derived reactive oxygen species were measured by FACS analysis and dihydrorhodamine 123 oxidation. In RCCs the MMP and TIMP expression profile was variable. The balance between MMP and TIMP was shifted towards MMP in comparison to matched normal controls. TAM were localized in a close vicinity to MMP expresssing tumor cells. As in RCC specimens, the expression of MMP and TIMP in the analyzed RCC cell lines varied. Hydrogen peroxide induced MMP-2 and -9 mRNA and protein expression, whereas TIMP-1 and TIMP-2 mRNA levels remained unaffected in cell lines. Thus, the ratio between MMP and TIMP was shifted towards MMP. Tumor cells did not increase the production of reactive oxygen species stimulation with phorbol ester or hydrogen peroxide. In RCC the balance between MMP and TIMP is disturbed. Oxidative stress potentially increases this imbalance. TAM might be one source of hydrogen peroxide thus supporting the invasive properties of RCCs.

Mycobacterial antigens induce apoptosis in human purified protein derivative-specific alphabeta T lymphocytes in a concentration-dependent manner.

The morbidity and lethality of tuberculosis is partially the result of an ineffective delayed-type hypersensitivity reaction which causes caseating granulomas in the lung and other organs. Recently we showed that during caseation besides macrophages numerous Fas+ FasL+ lymphocytes undergo apoptosis and postulated that this phenomenon may be due to activation-induced cell death (AICD) as a consequence of T-lymphocyte reactivation via bacillary antigens. As purified protein derivative of Mycobacterium tuberculosis (Mtb-PPD) provokes caseation in tuberculosis patients, the question arose as to whether bacillary antigens are responsible for AICD within caseous areas. In the present study Mtb-PPD-specific T helper 1 (Th1)-differentiated T lymphocytes were generated in vitro. Reactivation of these cells with Mtb-PPD resulted in a concentration-dependent hyporesponsiveness, which was due to an increase in apoptosis of gammadelta+, alphabeta+ CD4+ as well as alphabeta+ CD8+ T lymphocytes as assessed by the demonstration of the apoptosis-associated mitochondrial membrane protein 7A6 and DNA fragmentation. Blocking experiments demonstrated that Mtb-PPD antigens exploited the Fas/FasL system to induce apoptosis in Mtb-PPD-specific T lymphocytes. These results may support the hypothesis that in tubercle granulomas with caseation T lymphocytes undergo AICD following reactivation by bacillary antigens, thus contributing to the persistence of tuberculosis.

Cloning of a complementary DNA encoding the unique dendritic cell antigen Ki-M9.

Human sinus-lining cells (SLC) of the lymph node sinuses most probably represent accessory cells for the primary humoral immune response and have been shown to express a unique antigen recognized by the monoclonal antibody Ki-M9. To characterize this SLC-specific antigen further, a spleen cDNA library established in the expression vector lambda gt-11 was searched immunochemically for clones expressing the Ki-M9 antigen. Two recombinant phage clones revealed a cDNA with an open reading frame of 1666 bp encoding a 68-kDa protein. When fused with an expression vector that codes for the bacterial maltose-binding protein (MBP), the purified MBP-Ki-M9 fusion protein could be clearly detected by Western blot analysis. Furthermore, in situ hybridization with Ki-M9 cDNA as a probe confirmed the SLC-specific expression of the cloned cDNA. Additionally, Ki-M9 mRNA transcripts were detected in follicular dendritic reticulum cells of the secondary germinal centers, in a few cells of the perifollicular zone of the spleen, in some sinusoidal cells of liver, and in thymic reticular cells. A sequence database research revealed a strong homology to a murine cDNA. By applying non-radioactive in situ hybridization on mouse tissue, strong expression in SLC of the lymph node and metallophilic cells of the spleen in mouse tissue could be seen indicating that the Ki-M9 cDNA is highly conserved in the two species. Further computer analysis of the deduced amino acid sequence of the Ki-M9 antigen showed a large number of potential glycosylation sites and a PEST motive, which are characteristic for rapidly degraded membrane bound proteins and represent prerequisites for the function of this cell system in initiating the humoral immune response.