[MALT lymphoma of the orbit]. / MALT-Lymphom der Orbita.

MALT lymphomas of the orbit are rare orbital tumors; the differential diagnosis needs to exclude inflammatory pseudotumors of the orbit, but also benign lymphoproliferations, pseudolymphomas, and other orbital neoplasms. After histological confirmation of the diagnosis staging is necessary, and - as long as the disease is localized exclusively in the orbit - radiation therapy should be started. The clinical picture of MALT lymphoma and its differential diagnosis and treatment are discussed with reference to an actual case.

Expression of heat shock protein 70 in renal cell carcinoma and its relation to tumor progression and prognosis.

Heat shock proteins (HSPs) play an important role in the cellular response to environmental stress and exert a cytoprotective effect. Especially HSP70 is an effective inhibitor of apoptosis, suggesting a role of HSP70 in carcinogenesis and tumor progression. To explore the relevance of HSP70 in renal cell carcinomas (RCCs), we analyzed nuclear and cytoplasmic HSP70 protein expression in formalin-fixed tissue from 145 clear cell RCCs by immunohistochemistry as well as Western blot analysis. Nuclear HSP70 expression was found in all RCCs and 75% of the tumors also exhibited a cytoplasmic HSP70 staining. Importantly, RCCs showed significantly reduced cytoplasmic (p=0.001) and combined nuclear/cytoplasmic (p=0.0022) HSP70 expression when compared with their cells of origin. A significant (p=0.0176) decrease of nuclear HSP70 expression became evident from well to poorly differentiated clear cell RCCs. Quite similarly, a trend (p=0.0558) for reduced combined nuclear/cytoplasmic HSP70 expression was shown from early (pT1) to advanced (pT3) tumor stages. Nevertheless, no correlation between HSP70 expression and patients survival became evident. In conclusion, our investigation demonstrates a significant decrease of antiapoptotic HSP70 protein expression during carcinogenesis and during progression from well (G1) to poorly (G3) differentiated clear cell RCCs. Our results suggest that HSP70-mediated inhibition of apoptosis seems to be of minor importance for carcinogenesis and tumor progression in RCCs.

[Merkel cell carcinoma of the upper lid]. / Das Merkel-Zell-Karzinom des Oberlides.

AIMS: Merkel cell carcinoma (MCC) of the skin is a rare form of cutaneous malignancy of neuroendocrine origin with a propensity to form cutaneous and lymphogenous metastases. The tumor, affecting predominately elderly patients, has a significantly higher incidence in female patients (80%) compared to male patients (20%). The mainstay of therapy is surgical resection with possible adjuvant radio- or chemotherapy. CASE REPORT: A case of a 78-year-old patient with a MCC of the upper lid without lymph node involvement or distant metastasis is described. The tumor was resected and the defect closed by a temporal skin flap performing a temporary cantholysis. The clinical follow-up revealed an undisturbed eye lid function without any clinical or radiological signs of a locoregional or distant recurrence.

[Extracranial aneurysm of the carotid artery in a 12-year-old girl]. / Aneurysma verum der Arteria carotis im Kindesalter.

Extracranial aneurysms of the carotid artery in childhood are rare, and we found just nine cases described in the literature within the last 20 years. We report on the clinical appearance, diagnosis, and therapy of a carotid artery aneurysm in a 12-year-old girl and review the literature.

Synchronous occurrence of a follicular, papillary and medullary thyroid carcinoma in a recurrent goiter.

The simultaneous occurrence of different types of thyroid carcinoma in a single patient is an unusual event. We report the case of a 52-year-old man with the history of two previous thyroid operations for benign goiters, who developed a recurrent goiter. The patient was referred to our department for thyroidectomy. In the pathohistological examination the specimen showed a 5 cm follicular carcinoma and a 0.3 cm papillary microcarcinoma in the right lobe as well as a 1.5 cm medullary carcinoma in the left lobe. All tumors were clearly separated from each other, representing the pure entity of each type. Postoperatively, RET germline mutation was ruled out by sequence analysis of peripheral blood leucocytes. Postoperative I-131-radioiodine scan showed multiple lung and liver metastases, while calcitonin was negative. There is no known common cause of these three different tumor types and they developed most independently from each other. The personal history of our patient was interesting in two aspects: (1) he suffered a period of severe staphylococcal sepsis with temporal immunosuppression and (2) he worked for long years as a coremaker in a foundry. This work represented possible long term exposure to inhalative carcinogenous toxins like hydrazine, which caused thyroid parafollicular cell adenomas in an animal model.

Disturbed balance of expression between XIAP and Smac/DIABLO during tumour progression in renal cell carcinomas.

Dysregulation of apoptosis plays an important role in tumour progression and resistance to chemotherapy. The X-linked inhibitor of apoptosis (XIAP) is considered to be the most potent caspase inhibitor of all known inhibitor of apoptosis-family members. Only recently, an antagonist of XIAP has been identified, termed Smac/DIABLO. To explore the relevance of antiapoptotic XIAP and proapoptotic Smac/DIABLO for tumour progression in renal cell carcinomas (RCCs), we analysed XIAP and Smac/DIABLO mRNA and protein expression in the primary tumour tissue from 66 RCCs of all major histological types by quantitative real-time PCR, Western blot and ELISA. X-linked inhibitor of apoptosis and Smac/DIABLO mRNA expression was found in all RCCs. Importantly, the relative XIAP mRNA expression levels significantly increased from early (pT1) to advanced (pT3) tumour stages (P=0.0002) and also with tumour dedifferentiation (P=0.04). Western blot analysis confirmed the tumour stage-dependent increase of XIAP expression on the protein level. In contrast, mRNA and protein expression levels of Smac/DIABLO did not significantly change between early and advanced tumour stages or between low and high tumour grades. Consequently, the mRNA expression ratio between antiapoptotic XIAP and proapoptotic Smac/DIABLO markedly increased during progression from early (pT1) to advanced (pT3) tumour stages. Moreover, RCCs confined within the organ capsule (pT1 and pT2) exhibited a significantly lower XIAP to Smac/DIABLO expression ratio when compared with RCCs infiltrating beyond the kidney (pT3; P=0.01). Thus, our investigation demonstrates that the delicate balance between XIAP and Smac/DIABLO expression is gradually disturbed during progression of RCCs, resulting in a relative increase of antiapoptotic XIAP over proapoptotic Smac/DIABLO, thereby probably contributing to the marked apoptosis resistance of RCC.

Apoptosis induction in renal cell carcinoma by TRAIL and gamma-radiation is impaired by deficient caspase-9 cleavage.

TNF-related apoptosis-inducing ligand (TRAIL APO-2L) is a member of the TNF family and induces apoptosis in cancer cells without affecting most non-neoplastic cells. The present investigation is focused on apoptosis induction by combined exposure to TRAIL and ionising radiation (IR) in human renal cell carcinoma (RCC) cell lines. Here, we demonstrate that all RCC cell lines coexpress TRAIL and the death-inducing receptors, TRAIL-R1 and TRAIL-R2. Exposure to TRAIL alone induced marked apoptosis in three out of eight RCC cell lines. Combined exposure to TRAIL and IR resulted in a sensitisation to TRAIL-induced apoptosis in one RCC cell line only. Enhanced apoptosis induction by TRAIL in combination with IR was paralleled by an increase in PARP cleavage and activation of executioner caspase-3, whereas caspases-6 and -7 were not involved. Moreover, exposure to TRAIL and/or IR resulted in a marked activation of initiator caspase-8, possibly augmented by the observed reduction of inhibitory c-FLIP expression. In contrast to other tumour types, activation of initiator caspase-9 was not detectable in our RCC model system after exposure to TRAIL and/or IR. This lack of caspase-9 activation might be related to an impaired 'crosstalk' with the caspase-8 pathway as suggested by the missing Bid cleavage and to the appearance of an XIAP cleavage product known to inhibit caspase-9 activation. Deficient activation of caspase-9, therefore, might contribute to the clinically known resistance of human RCC against IR and also argues against an effective combination therapy with TRAIL and IR in this tumour type.

TRAIL-beta and TRAIL-gamma: two novel splice variants of the human TNF-related apoptosis-inducing ligand (TRAIL) without apoptotic potential.

Tumour necrosis factor (TNF) related apoptosis-inducing ligand (TRAIL/APO2L) is a recently identified member of the TNF family, which induces programmed cell death in a variety of neoplastic cell types, but not in most nonneoplastic cells. In this study, we report on the identification of two novel alternative splice variants of TRAIL in neoplastic and non-neoplastic human cells lacking either exon 3 (TRAIL-beta) or exons 2 and 3 (TRAIL-gamma). In both splice variants, loss of exon 3 resulted in a frame shift generating a stop codon with consecutive extensive truncation in the extracellular domain. Ectopic expression revealed a loss of proapoptotic potential for both alternative splice variants. In contrast to the predominantly cytoplasmatic localisation of GFP-tagged TRAIL-alpha and TRAIL-beta, TRAIL-gamma showed an additional association with the cell surface and nuclear membrane. In conclusion, alternative splicing might be involved in fine tuning of TRAIL-induced apoptosis and underlines the complexity of the TRAIL system.

FHIT expression in clear cell renal carcinomas: versatility of protein levels and correlation with survival.

Clear cell renal cell carcinomas (RCCs) are characterized by a deletion of chromosome 3p, which might result in the inactivation of the FHIT (fragile histidine triad) gene, a putative tumour suppressor gene. To explore the relevance of FHIT aberrations for tumour progression and prognosis in clear cell RCCs, FHIT protein expression was analysed in formalin-fixed tissue from 149 clear cell RCCs by immunohistochemistry. FHIT protein expression was found to be markedly reduced in all RCCs, when compared with adjacent non-neoplastic tubule epithelia. Although remaining below the FHIT levels of normal tubule epithelia, a significant increase of FHIT expression became evident from well (G1) to poorly (G3) differentiated clear cell RCCs (p=0.0001) and from low (pT1) to advanced (pT3) tumour stages (p=0.001). The log-rank test demonstrated a significant inverse correlation (p=0.0074) between FHIT expression and tumour aggressiveness as indicated by patient survival. Cox regression analysis revealed that FHIT expression is an independent prognostic parameter (p=0.0139) in clear cell RCCs. In conclusion, clear cell RCCs show a marked reduction of FHIT protein expression when compared with their putative cells of origin. In contrast to other tumour types, however, loss of FHIT protein expression is significantly less pronounced in poorly differentiated RCCs or advanced tumour stages. This versatility of FHIT expression during tumour progression suggests a role for reversible mechanisms of FHIT inactivation during the initiation and progression of clear cell RCCs.

Topotecan (Hycamtin) responsiveness in human renal carcinoma cell lines of the clear cell and papillary types.

BACKGROUND: Since no effective therapeutic approach is yet known for metastatic renal cell carcinoma (RCC), we analyzed the effects of topotecan (Hycamtin), a novel topoisomerase I-inhibitor, in RCC cell lines of the clear cell and papillary/chromophilic types. MATERIALS AND METHODS: The anti-proliferative and apoptosis-inducing effects of topotecan were analyzed in 20 RCC cell lines by MTT-assay and light microscopic apoptosis counting. Moreover, Bcl-2 and Bax expression was investigated by Northern blot and immunocytochemistry while the p53 mutation status was analyzed by DNA sequencing. RESULTS: Exposure to clinically relevant concentrations of topotecan (i.e. < or = 1 microg/ml) resulted in a significant (p<0.05) dose-dependent reduction of cell number in 17 out of 20 RCC cell lines. The reduction of cell number was paralleled by an increase in apoptotic cell death. Papillary/chromophilic RCCs exhibited a significantly (p<0.05) more pronounced responsiveness to topotecan than clear cell RCCs. Moreover, the effects of topotecan proved to be superior to those of 5-fluorouracil (5-FU), an anticancer drug currently used in the therapy of RCCs. No correlation became evident between responsiveness to topotecan and the expression levels of Bcl-2 and Bax. Moreover, the response to topotecan could not be correlated with the p53 mutation status of our RCC cell lines. CONCLUSION: Clinically relevant concentrations of topotecan induced apoptosis in RCC cell lines more effectively than 5-FU. Further testing will show whether topotecan-induced apoptosis can be exploited for the treatment of RCCs in vivo as well.

Deficient activation of CD95 (APO-1/Fas)-mediated apoptosis: a potential factor of multidrug resistance in human renal cell carcinoma.

The pronounced resistance of human renal cell carcinoma (RCC) to anticancer-induced apoptosis has primarily been related to the expression of P-glycoprotein and effective drug detoxification mechanisms. Because the CD95 system has recently been identified as a key mediator of anticancer drug-induced apoptosis, we analysed the contribution of the CD95 system to chemotherapy-induced apoptosis in four newly established RCC cell lines. Here, we demonstrate that all RCC cell lines expressed CD95-receptor and -ligand. Exposure to agonistic anti-CD95 antibodies resulted in induction of apoptosis and significant (P < 0.05) reduction of cell number in three out of four cell lines, indicating that the essential components for CD95-mediated apoptosis were present and functionally intact in the majority of these RCC cell lines. Moreover, treatment of cultures with bleomycin or topotecan, a novel topoisomerase I inhibitor with little substrate affinity for P-glycoprotein, led to induction of apoptosis and significant (P < 0.05) dose-dependent reduction of cell number in all RCC cell lines. Both anticancer drugs also induced upregulation of CD95 ligand expression in all cell lines. Additionally, augmentation of CD95 receptor expression was found in three RCC cell lines, including one p53-mutated cell line, whereas another p53-mutated cell line showed no or only a weak CD95 receptor upregulation after exposure to topotecan or bleomycin, respectively. Despite this upregulation of CD95 receptor and ligand, antagonistic antibodies directed against CD95 receptors or ligands could not inhibit induction of apoptosis by topotecan and bleomycin in any cell line. Thus, although a functionally intact CD95 signalling cascade is present in most RCC cell lines, the anticancer drugs topotecan and bleomycin that induce upregulation of CD95 receptor and ligand fail to effectively activate CD95-mediated apoptosis. This deficient activation of CD95-mediated apoptosis might be an important additional factor for the multidrug resistance phenotype of human RCCs.

Analysis of growth factor-dependent signalling in human epithelioid sarcoma cell lines. clues To the role of autocrine, juxtacrine and paracrine interactions in epithelioid sarcoma.

Human epithelioid sarcoma (ES) is an extremely aggressive soft tissue tumour of unknown histogenesis. Although growth factor-dependent signalling cascades significantly affect the biological behaviour of malignant tumours, little is known so far about their role in human ES. The present investigation, therefore, analyses the coexpression and function of different growth factors and their receptors in the human ES cell line GRU-1 and its clonal subpopulations (GRU-1A, GRU-1B and GRU-1C). As shown by Northern blot, flow cytometry, immunocytochemistry and MTT assay, all ES cell lines expressed transforming growth factor (TGF)-alpha and the epidermal growth factor receptor (EGF-R). Although no response to exogenous TGF-alpha was observed, antagonistic anti-EGF-R antibodies (at 20 microg/ml) induced significant (P<0.05) growth inhibition in all cell lines. All cell lines showed coexpression of platelet-derived growth factor (PDGF)-A and the corresponding receptors. Neutralisation of ES-derived PDGF by anti-hPDGF antibodies resulted in significant (P<0.05) growth inhibition of all clonal subpopulations. Although all cell lines expressed TGF-beta(1) as well as TGF-beta type I and type II receptors (TGF-BI-R and TGF-BII-R), growth inhibition (P<0.05) by exogenous TGF-beta(1) was achieved in the clonal subpopulations only and not in the parental cell line. No ES cell line expressed acidic fibroblast growth factor (FGF) but stimulation of FGF type 3 and type 4 receptors (FGF-3R and FGF-4R) by exogenous acidic FGF (aFGF) resulted in a marked (P<0.05) acceleration of proliferation in all cell lines. In conclusion, our investigation suggests an intricate network of autocrine, juxtacrine and paracrine signalling between ES tumour cells and adjacent non-neoplastic stromal cells.

[Duodenal diverticulum--an unusual manifestation of recurrent retroperitoneal liposarcoma]. / Duodenaldivertikel--ein ungewöhnliches Erscheinugsbild eines retroperitonealen Liposarkomrezidivs.

The treatment of choice in retroperitoneal liposarcoma is curative R0 resection. However, there are high rates of reoperation due to recurrence. Our present case report shows difficulties in detecting recurrence due to atypical configuration. Eventually a huge diverticulum of the duodenum combined with leiomyoma in its neck area was histopathologically identified as a recurrent liposarcoma.

Differential response to transforming growth factor (TGF)-alpha and fibroblast growth factor (FGF) in human renal cell carcinomas of the clear cell and papillary types.

The clear cell and the papillary types of human renal cell carcinoma (RCC) are distinct tumour entities with marked differences in their biological properties. Because growth factors are considered to affect profoundly the biological behaviour of malignant tumours, we compared the expression and function of transforming growth factor (TGF)-alpha and fibroblast growth factor (FGF) in both types of RCCs. Both in vivo and in vitro expression of TGF-alpha, epidermal growth factor-receptor (EGF-R), FGF-2 and FGF type 3- and 4-receptors was found in RCCs of both types. However, marked differences between clear cell and papillary RCCs became evident for TGF-alpha secretion, which could be demonstrated in 20 out of 24 (83%) clear cell RCCs but in only two out of four (50%) papillary tumours. Moreover, the mean TGF-alpha secretion rate in clear cell RCCs significantly (P<0. 05) exceeded that of papillary RCCs. Because the expression of growth factor receptors could not prove the corresponding signalling cascades were functional, tumour cell proliferation was tested after exposure to exogenous TGF-alpha or FGF-1. These experiments demonstrated that papillary RCCs did not respond significantly to exogenous TGF-alpha or FGF-1, whereas eight (33%) (TGF-alpha) and 11 (46%) (FGF-1) out of 24 clear cell RCCs responded with significant (P<0.05) growth stimulation. In conclusion, our investigation presents data indicating that TGF-alpha and FGF are functionally involved in the progression of clear cell RCCs, directly stimulating proliferation by autocrine and/or paracrine actions. In contrast, TGF-alpha and FGF did not directly stimulate the proliferation of our papillary RCCs, thereby suggesting functional defects or a blockade in the corresponding signalling cascades. This differential functionality might contribute to the more aggressive behaviour of clear cell RCCs.

Sensitivity to TRAIL/APO-2L-mediated apoptosis in human renal cell carcinomas and its enhancement by topotecan.

TRAIL (APO-2L) is a newly identified member of the TNF family and induces apoptosis in cancer cells without affecting most non-neoplastic cells, both in vitro and in vivo. Our study focused on the expression and function of TRAIL and its receptors in renal cell carcinoma (RCC) cell lines of all major histological types. Here, we demonstrate that all RCC cell lines express TRAIL as well as the death-inducing receptors TRAIL-R1 (DR4) and TRAIL-R2 (Killer/DR5). Exposure to TRAIL induced apoptosis in 10 of 16 RCC cell lines. Remarkably, five of six TRAIL-resistant RCC cell lines exhibited high levels of TRAIL expression. Topotecan, a novel topoisomerase I inhibitor, induced upregulation of TRAIL-R2 as well as downregulation of TRAIL. Neutralization of TRAIL with recombinant soluble TRAIL-R1-Fc and TRAIL-R2-Fc failed to inhibit topotecan-induced apoptosis indicating that topotecan-induced cell death can occur in a TRAIL-independent fashion. However, exposure to topotecan resulted in an enhancement of TRAIL-induced apoptosis in all primarily TRAIL-resistant RCC cell lines. This synergistic effect of cotreatment with Topotecan and TRAIL may provide the basis for a new therapeutic approach to induce apoptosis in otherwise unresponsive RCC.

Diagnostic accuracy of effusion cytology.

The aim of this investigation was to report on the diagnostic accuracy of conventional effusion cytology. Cytological diagnoses of 300 pleural effusions and 300 ascites were compared with clinical and/or histological follow-ups of the respective patients. Sensitivity of our cytological diagnoses on pleural effusions was 50.0%, specificity 97.0%, positive predictive value 95.7%, and negative predictive value 86.4%. Sensitivity in ascitic effusions was 62.4%, specificity 98.0%, positive predictive value 100.0%, and negative predictive value 88.3%; 5.8% of diagnoses for pleural and 4.4% for peritoneal effusions were suspicious or doubtful. The overall false-positive rate was 0.5%, while the false-negative rate was 31.5%. False-negative results were due to sampling errors in 71% of pleural and 73% of peritoneal effusions and to screening errors in 29% and 27%, respectively. Our data and those from the literature show that diagnostic accuracy of effusion cytology is still unsatisfactory and should be improved. Therefore, the use of different adjuvant methods is recommended.

Resistance to CD95 (APO-1/Fas)-mediated apoptosis in human renal cell carcinomas: an important factor for evasion from negative growth control.

Disorders in negative growth control by CD95 (APO-1/Fas)-mediated apoptosis have been suggested to facilitate immune evasion of neoplastic cells and resistance to anticancer drugs. The present report describes the expression and function of CD95 receptor and ligand in human renal cell carcinomas (RCC) of all major histological types, presenting in vitro data on RCC cell lines (n = 30) and ex vivo observations in RCC tissue samples (n = 30). Using RT-PCR, flow cytometry and immunostaining, expression of CD95 receptor and ligand was found in human RCC of all major histological types. The expression levels of CD95 ligand, however, were rather low. Despite constitutive CD95 receptor expression, resistance to CD95-mediated apoptosis became evident from the weak response to agonistic anti-CD95 antibodies, which induced a low increase of apoptosis in only 9 of 30 RCC cell lines. After IFN-gamma pretreatment, however, apoptosis triggered by agonistic anti-CD95 antibodies was observed in 22 of 30 RCC cell lines. These data indicated that the machinery required for CD95-induced cell death was present, albeit inactive in most RCC. Inhibition of protein synthesis by cycloheximide resulted in increased sensitivity to agonistic anti-CD95 antibodies, suggesting a role for short-lived apoptosis-protective proteins in the resistance of RCC to CD95-mediated apoptosis. Moreover, we demonstrated the secretion of soluble CD95 receptor which might contribute to this resistance as well. In conclusion, resistance rather than responsiveness to CD95-mediated apoptosis is a key feature of human RCC. This resistance might facilitate evasion from negative growth control and contribute to the failure of cytotoxic drugs in the treatment of human RCC.

Functional intactness of stimulatory and inhibitory autocrine loops in human renal carcinoma cell lines of the clear cell type.

PURPOSE: The aim of the present study was to analyze the contribution of different stimulatory and inhibitory growth factors to the deregulated proliferation of human RCCs. MATERIALS AND METHODS: The expression of different growth factors and their corresponding receptors were analyzed by Northern blot, FACS, ELISA and immunocytochemistry in 13 permanent human RCC cell lines of the clear cell type. Moreover, the functional intactness of growth factor-related signal transduction pathways was investigated. RESULTS: All RCC cell lines expressed EGF-receptor mRNA and protein and 10 cell lines secreted TGF-alpha. Exogeneously added TGF-alpha resulted in a significant (p < 0.05) stimulation of growth in 6 RCC cell lines and a significant (p < 0.05) inhibition of proliferation in 3 cell lines. PDGF B and the corresponding type beta receptor were expressed in a single cell line. mRNA expression of PDGF A and PDGF-alpha-receptor as well as IGF-1 and its receptor could not be detected in any cell line. Eleven RCC cell lines expressed TGF-beta 1 mRNA and in all cell lines TGF-beta 1 secretion into the supernatant could be demonstrated. Whereas all cell lines exhibited TGF-beta type II-receptor mRNA, type I-receptor mRNA could be detected only in 3 cell lines. TGF-beta type III-receptor was observed in 1 cell line. Exogeneously added TGF-beta1 resulted in a significant (p < 0.05) inhibition of proliferation in 7 RCC cell lines. CONCLUSION: Clear cell RCCs exhibit a complex and heterogeneous expression pattern for various growth factors and their receptors. Growth factor secretion and intact signal transduction pathways in most clear cell RCCs facilitate an intricate modulation of RCC growth by autocrine and paracrine interactions between tumor cells and host tissue.

Acquisition of TGF-beta 1 resistance: an important progression factor in human renal cell carcinoma.

The balance of growth regulation in tumors can be profoundly disturbed by defects in the transforming growth factor-beta 1 (TGF-beta 1) system. Thus far, investigations into the secretion of TGF-beta 1, the expression of its type I, II, and III receptors, as well as the functional intactness of the TGF-beta 1 signal transduction pathways in human renal cell carcinomas (RCC) have been lacking. The objective of the present study, therefore, was to elucidate the role of the TGF-beta 1 system in RCC. We were able to determine the status of this system in 20 primary RCC and in 30 newly established human RCC cell lines of all major histologic types. All primary RCC showed expression of TGF-beta 1 and its type I and II receptors by immunohistochemistry, irrespective of histologic type. In vitro, all RCC cell lines secreted TGF-beta 1 protein as a biologically inactive complex, which cannot interact with cell-surface receptors. Type I ALK-5-receptor mRNA and protein were detected in 29 RCC cell lines, whereas type I ALK-2-receptor mRNA was found in all cell lines. Type II-receptor mRNA and protein could be demonstrated in all cell lines analyzed, and type III-receptor mRNA was observed in five RCC cell lines. Exogenously added, biologically active TGF-beta 1 (1 ng/ml) resulted in significant (p < 0.05) inhibition of proliferation in 14 of 30 RCC cell lines. Sixteen of thirty RCC cell lines, however, proved to be TGF-beta 1-resistant. This resistance could not be explained by mutations in two "hot spot" regions of the type II-receptor gene (bp 622 to 795 and bp 1868 to 2019), as was demonstrated by DNA sequencing in the TGF-beta 1-resistant RCC cell lines. In conclusion, our observations are the first to provide evidence of an "escape" from the negative growth control of TGF-beta 1 by a significant proportion of RCC, suggesting that the acquisition of TGF-beta 1 resistance is an important progression factor for human RCC.

Chromophilic renal cell carcinoma: cytomorphological and cytogenetic characterisation of four permanent cell lines.

Chromophilic renal cell carcinoma is a distinct type of human renal cancer, only recently recognised and defined by its characteristic histomorphological aspect and cytogenetic aberrations. We are the first to report on the establishment and cytogenetic characterisation of a panel of four permanent cell lines, i.e. chromphi-1, -2, -3 and -4, derived from strictly defined renal cell carcinomas (RCCs) of the chromophilic type and kept in continuous culture for up to 5 years. Immunohistochemistry revealed coexpression of vimentin and cytokeratins in all cell lines the cytokeratin polypeptide patterns, however, varying between the different cell lines. By light and transmission electron microscopy, various amounts of cytoplasmatic glycogen deposition were observed, being most pronounced in chromphi-3 and -4. The mean population doubling time ranged from 24 h (chromphi-1) to 51 h (chromphi-4). Chromphi-1 tumour cells produced slowly growing tumours in nude mice using the subrenal capsule assay. In all cell lines, cytogenetic analysis revealed numerical chromosomal aberrations known to be characteristic for chromophilic RCCs, i.e. loss of the Y chromosome, tri- or tetrasomy of chromosomes 7 and 17 as well as various combinations of additional structural and numerical chromosomal aberrations. Karyological aberrations were least pronounced in chromphi-2 and most complex in chromphi-1. Chromosomal aberrations typically affecting the short arm of chromosome 3 in clear cell RCCs were not observed in any of our cell lines.