Daxx-beta and Daxx-gamma, two novel splice variants of the transcriptional co-repressor Daxx.

Daxx is involved in transcriptional control and apoptosis. It comprises several domains, including a regulatory C terminus that is responsible for the interaction with numerous proteins such as p53, promyelocytic leukemia protein (PML), and Hsp27. Here, we describe the identification and characterization of two novel variants of Daxx termed Daxx-ß and Daxx-γ, which are generated by alternative splicing. Alternative splicing results in a truncated regulatory C terminus in both proteins. As a consequence, Daxx-ß and Daxx-γ show a markedly decreased affinity to PML, which in turn is associated with a different subnuclear localization of these proteins compared with Daxx. Although Daxx is localized mainly in PML-oncogenic domains (PODs) Daxx-ß and Daxx-γ display a distinct distribution pattern. Furthermore, Daxx-ß and Daxx-γ show a decreased affinity to p53 also due to the truncated C terminus. We provide evidence that the p53 recruitment into PODs is Daxx isoform-dependent. The decreased affinity of Daxx-ß/-γ to p53 and PML results in a diffuse localization of p53 throughout the nucleus. In contrast to Daxx, Daxx-ß and Daxx-γ are unable to repress p53-mediated transcription. Therefore, alternative splicing of Daxx might indicate an additional level in the cellular apoptosis network.

PIDDosome expression and the role of caspase-2 activation for chemotherapy-induced apoptosis in RCCs.

BACKGROUND: The importance of caspase-2 activation for mediating apoptosis in cancer is not clear and seems to differ between different tumour types. Furthermore, only few data have been obtained concerning the expression of caspase-2, which can be alternatively spliced into caspase-2L and caspase-2S, and the other PIDDosome members PIDD and RAIDD in human tumours in vivo. We, therefore, investigated their expression in renal cell carcinomas (RCCs) of the clear cell type in vivo and analysed the role of caspase-2 in chemotherapy-induced apoptosis in RCCs in vitro. METHODS: The analyses were performed by semiquantitative real-time PCR, Western Blot and Caspase-2 Assay. RESULTS: Our in vivo results showed an overall decrease in proapoptotic caspase-2L expression during tumour progression due to an increase in the relative share of caspase-2S mRNA in total caspase-2 mRNA expression. Furthermore, an increase in the expression of PIDD and RAIDD could be observed. In contrast, antiapoptotic BCL-2 expression increased only during early tumour stages, whereas expression decreased in pT3 RCCs. In vitro, caspase-2 activation in RCC cell lines coincidenced with sensitivity of tumour cells towards Topotecan-induced apoptosis. However, inhibition of caspase-2 could not prevent Topotecan-induced apoptosis. Interestingly, Topotecan-resistance could be overcome by the apoptosis-sensitizing drug HA14-1. CONCLUSION: Our study confirms the concept of a shift towards a more antiapoptotic transcriptional context during tumour progression in RCCs. Furthermore, it shows that caspase-2 participates in chemotherapy-induced apoptosis in RCCs although it is not mandatory for it. Additionally, inhibition of antiapoptotic BCL-2 family members might provide a possible way to overcome chemotherapy resistance of RCCs.

Combined esophageal injury complicated by progression to a second perforation: a case report.

INTRODUCTION: Intramural dissection of the esophagus is a rare disorder characterized by a lesion between the submucosa and mucosa dividing the esophagus into a false and true lumen. The etiology of esophageal dissection remains uncertain but it affects predominantly women in their seventies and eighties. Symptoms may include uncharacteristic ones such as retrosternal pain, odynophagia or dysphagia. Conservative management is thought to be adequate and surgery should only be performed if complications such as abscess formation or perforation appear. Here we report the case and surgical management of a combined esophageal perforation and dissection. CASE PRESENTATION: We report the case of a combined esophageal perforation and dissection in a 45-year-old Caucasian woman with a history of relapsing periods of dysphagia since her childhood. The clinical course in this patient was complicated by progression to a second perforation, which made a definitive surgical management by esophagectomy necessary. CONCLUSION: To the best of our knowledge, this is the first reported case of a combined esophageal perforation and dissection complicated by progression to a second perforation. This emphasizes that cautious and intensive observation is necessary in patients with esophageal dissection.

Is there a role for the Fas-/Fas-Ligand pathway in chemoresistance of human squamous cell carcinomas of the head and neck (SCCHN)?

The aim of the present investigation was to determine the expression of the Fas-receptor/ligand system in established cell lines of squamous cell carcinomas of the head and neck (SCCHN), and to study it's functional impact on chemotherapy-induced apoptosis in these SCCHN cell lines. We observed constitutive expression of Fas and FasL in 13 SCCHN cell lines by RT-PCR, Southern-blotting and immunocytochemistry, respectively. Administration of the agonistic Fas-antibody CH-11 led to a significant reduction of viable cells in the colorimetric MTT-assay in 5 out of 13 (38%) cell lines tested and preincubation with Interferon-gamma (IFN-gamma) rendered 3 (23%) primarily resistant cell lines sensitive. Cisplatin (cDDP) and bleomycin (BLM) caused dose-dependent cytotoxicity in all cell lines as determined by the 50% inhibitory concentration (IC(50)) and induction of apoptosis. Furthermore, both antineoplastic agents led to an enhanced surface expression of Fas and FasL in all cell lines, and this effect was independent of the respective p53-status. This upregulation of Fas/FasL surface expression increased preexisting Fas-sensitivity only, but failed to make primarily resistant cell lines undergo Fas-mediated growth reduction or apoptosis. Vice versa, blockade of Fas-receptor-ligand-interactions by monoclonal antibodies directed against FasL was able to attenuate the cytotoxic effect of cDDP and BLM in 2 out of 5 (40%) cell lines tested only. In conclusion, in contrast to many other solid tumors, the Fas/FasL-system does not seem to play an exclusive role in anticancer drug mediated apoptosis in SCCHN.

HA14-1 is able to reconstitute the impaired mitochondrial pathway of apoptosis in renal cell carcinoma cell lines.

Renal cell carcinomas (RCCs) exhibit a marked resistance towards apoptosis. Although most apoptotic stimuli converge at the level of the mitochondria, little is known about the mitochondrial apoptosis pathway in renal cell carcinomas. The aim of the present study, therefore, was to investigate the functionality of the mitochondrial apoptosis pathway in renal cell carcinoma cell lines by exposure to TRAIL, etoposide, HA14-1 and betulinic acid activating the mitochondria by different mechanisms. Sensitivity to TRAIL-induced apoptosis correlated with cleavage of the initiator caspase-8, but the mitochondrial apoptosis pathway was not induced. Similarly, etoposide and betulinic acid could not induce mitochondrial damage. In contrast, HA14-1 was able to activate mitochondrial apoptosis, thereby demonstrating functionally inducible signalling pathways downstream of the mitochondria. The intactness of the pathways upstream of the mitochondria was shown by pretreatment of TRAIL-sensitive cell lines with HA14-1, which could reconstitute TRAIL-induced mitochondrial damage and resulted in a synergistic apoptosis induction. Our results demonstrate that the apoptotic pathways upstream and downstream of the mitochondria are intact and inducible in renal cell carcinoma cell lines. However, resistance towards mitochondrial apoptosis is located on the level of the mitochondria themselves.

Disturbed XIAP and XAF1 expression balance is an independent prognostic factor in gastric adenocarcinomas.

BACKGROUND: Dysregulation of apoptosis is a key factor in carcinogenesis and tumor progression. X-linked inhibitor of apoptosis (XIAP) is the most potent member of the inhibitor of apoptosis protein (IAP) family, which directly inhibits apoptosis by binding to caspases. Antagonists of XIAP have recently been identified: second mitochondria-derived activator of caspase/direct IAP-binding protein with low PI (Smac/DIABLO) and XIAP-associated factor 1 (XAF1). However, little research has been conducted on the association between gastric cancer survival and the mechanism of apoptosis involving XIAP and its antagonists, Smac/DIABLO and XAF1. METHODS: XIAP, Smac/DIABLO, and XAF1 expression was analyzed by immunohistochemistry (IHC) in 187 gastric adenocarcinomas. Correlations between XIAP, Smac/DIABLO or XAF1 expression and clinicopathological factors were analyzed. Disease-specific survival after surgery was examined. RESULTS: Of 187 samples, XIAP was overexpressed in 140, Smac was overexpressed in 117, and XAF1 was overexpressed in 106. Individually, XIAP, Smac, and XAF1 were not significantly associated with disease-specific survival. However, patients showing high expression of XIAP and low expression of XAF1 had significantly poorer survival when compared with other groups (P = 0.024). CONCLUSION: The expression balance of XIAP and XAF1 is an independent prognostic factor in gastric adenocarcinoma.

Multiple giant scalp metastases of a follicular thyroid carcinoma.

BACKGROUND: The occurrence of skin metastases are rare events in the course of a follicular thyroid carcinoma (FTC) and usually indicate advanced tumor stages. The scalp is the most affected area of these metastases. CASE PRESENTATION: We present a case of a 76 year old Woman with multiple giant scalp metastases of a follicular carcinoma. These metastases had been resected and wounds had been closed with mesh graft. The 14-months follow up is presented. CONCLUSION: We demonstrate another case with multicentric form. Because of its location and size a primary wound closure was not possible. A healing could be reached using vacuum therapy and mesh graft transplantation.

Caspase-8 and its inhibitors in RCCs in vivo: the prominent role of ARC.

Activation of the initiator-caspase, caspase-8 is under tight control of multiple antiapoptotic regulators including ARC, cFlip(S), cFlip(L) and PED/PEA-15. Since there is little data regarding the expression of caspase-8 and its antiapoptotic regulators in human tumours in vivo, we analysed their expression in renal cell carcinomas (RCCs) to identify which of these genes might be crucial for the well known impaired apoptosis and--as a result--resistance towards chemotherapy and ionizing radiation of RCCs. Caspase-8, cFlip(S), cFlip(L) and PED/PEA-15 mRNA expression was significantly increased only in early stages of RCCs compared to non-neoplastic renal tissue. In contrast, ARC mRNA expression was significantly increased in RCCs of all stages without differences between the tumour stages and grades. Importantly, the relative mRNA expression ratio between ARC and caspase-8 was significantly increased during carcinogenesis and tumour progression. In contrast, the relative mRNA expression ratio between cFlip(S), cFlip(L) or PED/PEA-15 and caspase-8 remained constant during all tumour stages. In conclusion, our analysis revealed that ARC is the only caspase-8 inhibiting regulator being constantly overexpressed in RCCs. Furthermore, the balance between antiapoptotic ARC and proapoptotic caspase-8 is the only one to be disturbed during carcinogenesis and tumour progression of RCCs. This inhibition of Caspase-8 might therefore be one example for the multiple antiapoptotic functions of ARC in RCCs possibly contributing to the marked resistance of RCCs towards radio- and chemotherapy and reflects a shift of gene expression towards a more antiapoptotic context in RCCs.

Hemoglobin-glutamer 200 reduces reperfusion injury of the cold preserved rat liver by induction of heme oxygenase-1.

Microcirculatory failure after cold liver preservation and reperfusion impairs tissue oxygenation and causes additional organ damage. Hemoglobin-glutamer (HbG) 200 is a hemoglobin-based oxygen carrying solution capable to improve organ oxygenation. The aim of this study was to evaluate its potential to decrease reperfusion injury after cold liver preservation. Therefore, Wistar rat livers were stored at 4 degrees C for 24 h and reperfused in the isolated perfused rat liver model with a sanguineous perfusate for 180 min. The perfusate consisted of rat blood and Krebs-Henseleit solution (Group A), supplemented by either HES 6% (Group B), or HbG (Groups C and D). In Group D heme oxygenase (HO) activity was blocked by intraperitoneal tin protoporphyrin-IX application before organ harvest. HbG supplementation increased the perfusate hemoglobin by 3,3 g/dL. After 180 min reperfusion perfusate alanine aminotransferase levels (72 +/- 27 micro/L) were significantly reduced in Group C, compared with Groups A and B (140 +/- 28 micro/L and 203 +/- 62 micro/L, respectively). These results correlated with a significant increase of HO-1 expression and activity during reperfusion. These effects could be abolished by tin protoporphyrin-IX application. HbG has been proven to be effective to reduce cold liver preservation-reperfusion injury. The positive effect on reperfusion injury depends on the induction of HO-1, which increases the bilirubin production, an important antioxidant acting as intracellular radical scavenger.

An uncommon cause of gastro-duodenal ulceration.

Gastrointestinal ulcers occur frequently and are mainly caused by H. pylori infection. In this report, we present a rare case of gastro-duodenal ulcer following selective internal radiation therapy (SIRT). SIRT is a palliative treatment for unresectable liver tumours. During SIRT, (90)Y-microspheres are infused into the hepatic artery. Pre-treatment evaluation for the presence of arterial shunts to neighbouring organs should be determined in order to avoid complications of SIRT.

Paclitaxel (Taxol)-induced apoptosis in human epithelioid sarcoma cell lines is enhanced by upregulation of CD95 ligand (FasL/Apo-1L).

PURPOSE: Metastasizing epithelioid sarcoma (ES) is an extremely aggressive tumor, because conventional chemotherapy and irradiation are largely ineffective. Here, we analyzed the impact of the CD95-mediated drug-induced apoptosis in ES cell lines. METHODS: The effects of paclitaxel (Taxol) and 5-FU were determined by MTT assay. The extent of apoptosis was analyzed by light microscopy and Annexin V staining (flow cytometry). The expression of death receptors and ligands was defined by RT-PCR, Western blotting and flow cytometry. RESULTS: All cell lines expressed CD95, but not the CD95 ligand. The CD95 activation resulted in apoptosis and cell death in all cell lines. Both paclitaxel and 5-FU are able to trigger apoptosis, and furthermore, to upregulate CD95, whereas only paclitaxel increases CD95 ligand expression. Neutralizing antibodies directed against CD95 ligand effectively inhibited paclitaxel-induced cell death, thereby providing evidence for a direct involvement of the CD95 system in paclitaxel-induced apoptosis. CONCLUSIONS: Concomitant upregulation of CD95 receptor and ligand may significantly enhance the response of ES to anticancer drugs. As evident from the differential response of our clonal ES subpopulations to paclitaxel and 5-FU, effective activation of the CD95 system depends on intrinsic properties of both the chemotherapeutic agent and target cell population.

Carcinogenic hypergastrinemia: signet-ring cell carcinoma in a patient with multiple endocrine neoplasia type 1 with Zollinger-Ellison's syndrome.

CONTEXT: Gastric neuroendocrine tumors are rare neoplasms that originate from gastric enterochromaffin-like (ECL) cells in the oxyntic mucosa. Gastrin and its derivates have been reported to regulate epithelial cell proliferation, migration, and differentiation. Mutations in the epithelial cadherin (E-cadherin) gene have been shown to be associated with the occurrence of diffuse gastric carcinomas in affected families. OBJECTIVE: In this study we investigated the histopathological and molecular findings in the gastrointestinal wall of a patient with multiple endocrine neoplasia type 1 with malignant duodenal gastrinoma and multiple gastric ECL cell tumors, who additionally developed a signet-ring cell carcinoma of the stomach. DESIGN AND PATIENT: Biopsies from the gastrointestinal tract of a patient with multiple endocrine neoplasia type 1 were immunostained for vesicular monoamine transporter-2 and E-cadherin. Nonamidated gastrin products were measured in the serum of the patient using antibodies that react with progastrin, Gly-extended, and amidated gastrins. Genetic analyses were performed to exclude germ-line mutations within the E-cadherin gene. RESULTS: Immunohistochemical studies of gastric ECL cell tumors showed a largely diminished E-cadherin expression in comparison to gastric surface mucosa cells and a loss of E-cadherin expression in the cells of the signet-ring carcinoma. Detailed biochemical measurements revealed progastrin concentrations that were approximately 20%, and Gly-gastrin concentrations that were approximately 10% the amidated gastrin concentrations in plasma. Molecular analyses revealed no E-cadherin germ-line mutation. CONCLUSION: Our immunohistochemical studies might suggest that the gastrinoma-associated excessive progastrin tissue concentrations led to diminished expression of E-cadherin within the gastric mucosa and promoted tumor development of a signet-ring cell carcinoma.

Differential gene expression in anticancer drug- and TRAIL-mediated apoptosis in renal cell carcinomas.

Renal cell carcinomas (RCC) exhibit marked differences in susceptibility towards anticancer drug- and TRAIL-induced apoptosis. However, the underlying mechanisms determining apoptosis-sensitivity or -resistance are not well understood. The purpose of this study was to compare gene expression patterns induced by DNA-damage- and death receptor-induced apoptosis and to detect differentially expressed genes responsible for differences in apoptosis-susceptibility. Therefore, we performed a comparative cDNA-array analysis in an apoptosis-resistant and an apoptosis-sensitive RCC cell line. In the sensitive cell line an upregulation of multiple E2F1- and p53-inducible proapaptotic and cell-cycle regulating target genes by Topotecan as well as TRAIL was observed. Interestingly, several antiapoptotic NFkappaB-dependent target genes were also induced. In the resistant cell line, however, only a small number of E2F1-, p53- and NFkappaB-dependent target genes were differentially regulated. Conclusively, anticancer drug- as well as TRAIL-sensitivity go along with an upregulation of multiple proapoptotic genes. In contrast, the mechanisms of apoptosis-resistance are-at least in part-located upstream of gene induction and seem not to depend upon upregulation of de-novo-synthesized antiapoptotic genes. Conclusively, the proapoptotic stimuli are confronted with a cellular context which allows apoptosis to be conducted-in the sensitive cell line-or not-in the resistant cell line.

Bone histomorphology may be unremarkable in diabetes mellitus.

BACKGROUND AND PURPOSE: Histomorphological studies on bone in human diabetes mellitus are scarce. The aim of this study was to observe the histomorphological appearance of bone in amputation specimens from feet of patients with diabetes mellitus. MATERIAL AND METHODS: Routine histopathology reports on 45 amputation specimens were evaluated, provided the osteotomy was located in unaffected bone tissue. The bone morphology of regions affected with gangrene and/or osteomyelitis was considered, as well as the morphology at the dissection margin at a distance from the affected parts. The specimens were obtained from 43 diabetic patients, most of whom exhibiting the so-called neuroischemic diabetic foot with infection. The patients' age ranged from 50 to 92 years, duration of diabetes from 0 to 52 years; polyneuropathy was present in 36, peripheral ischemic vessel disease (PIVD) in 30, and renal failure in 24 of them, respectively. RESULTS: There were 22 clinical cases of osteomyelitis, 20 cases of gangrene (including three cases of necrosis without surrounding inflammation), and three cases of pressure ulcer, which were treated by amputation of 24 toes, and resection of 21 metatarsal bones, respectively. Histomorphology showed osteomyelitis (n=29), bone necrosis (n=1), myelofibrosis (n = 8), and normal bone (n=7) at the affected sites, compared to normal bone (n=26), myelofibrosis (n=12), and osteoporosis (n=7) at the osteotomy sites. In cases of clinical gangrene, bones were also affected by osteomyelitis, but less so than in cases of clinical osteomyelitis (8/18 vs. 22/22; p<0.001). Bone tissue at the osteotomy sites was normal--with some myelofibrosis--in both conditions. CONCLUSION: This pilot study shows that histomorphology of unaffected foot bone is mostly not abnormal in diabetic patients with neuropathy and PIVD. Further study is necessary to corroborate this preliminary evidence of absence of a "diabetic osteopathy" in the diabetic foot.

Disturbed expression of the apoptosis regulators XIAP, XAF1, and Smac/DIABLO in gastric adenocarcinomas.

Dysregulation of apoptosis plays an important role in carcinogenesis and tumor progression. Whereas x-linked inhibitor of apoptosis (XIAP) is a potent inhibitor of apoptosis, its antagonists second mitochondria-derived activator of caspases/direct IAP binding protein with low PI (Smac/DIABLO), and XIAP-associated factor 1 (XAF1) promote apoptosis. To explore the relevance of XIAP, Smac/DIABLO, and XAF1 for carcinogenesis and tumor progression, we analyzed 46 primary gastric adenocarcinomas and non-neoplastic gastric mucosa samples by quantitative real-time polymerase chain reaction. XIAP, Smac/DIABLO, and XAF1 expression was found in all non-neoplastic gastric mucosa samples and all adenocarcinomas. XIAP expression levels did not change between non-neoplastic gastric mucosa and adenocarcinomas or between carcinomas of early and advanced stages. Although Smac/DIABLO expression was significantly (P=0.01) higher in carcinomas, the ratio of XIAP to Smac/DIABLO expression remained stable between non-neoplastic mucosa and carcinomas. XAF1 expression had the tendency to decrease from non-neoplastic mucosa to advanced adenocarcinomas. Importantly, the ratio of XIAP to XAF1 expression significantly (P=0.03) increased from non-neoplastic mucosa to adenocarcinomas and the increase was even higher in carcinomas of advanced stage (P=0.01). Moreover, expression of the XAF1 splice variants differing in the zinc-finger domain essential for XIAP-binding was analyzed and revealed a significant higher (P=0.03) variant-2/variant-1 ratio in advanced carcinomas. In conclusion, an increased expression ratio of XIAP to XAF1 in combination with a disturbed expression of the XAF1 splice variants could be shown in gastric adenocarcinomas. These marked imbalances probably result in an impaired ability for XAF1 to antagonize the effects of XIAP thereby contributing to apoptosis-resistance and generating an important growth advantage.

Giant fibrovascular polyp of the esophagus.

Fibrovascular polyps of the esophagus are benign, pedunculated tumors that consist mostly of connective tissue and can reach impressive sizes. They arise from the upper third of the esophagus and may produce symptoms of dysphagia, progressive weight loss and regurgitation. The most serious clinical presentation is asphyxia secondary to laryngeal obstruction. Despite their size, diagnosis may be difficult. The location of the stalk and the vascularity makes surgical resection the preferred mode of removal of these unusual polyps.

TRAIL-R4-beta: a new splice variant of TRAIL-receptor 4 lacking the cysteine rich domain 1.

Transcriptional modification by alternative splicing is known to be involved in the regulation of programmed cell death. Recently, alternative splice variants of the TNF-related apoptosis inducing ligand (TRAIL/APO2L) and of the death receptor TRAIL-R2/DR5 have been identified. In this study, we report the identification of a novel alternative splice variant of the decoy receptor with a truncated death domain TRAIL-R4 lacking exon 3, which we designated TRAIL-R4-beta. As revealed by BLAST search we identified the genomic organisation of the TRAIL-R4 gene which consists of 9 exons. Loss of exon 3 resulted in the truncation of the first complete cysteine rich domain 1 which is known to be involved in ligand-receptor-complex. In conclusion, alternative splicing might be involved in functional fine-tuning of TRAIL-induced programmed cell death.

A case of a pT3, HPV 52-positive vulvar carcinoma in an 18-year-old woman.

BACKGROUND: Vulvar carcinoma in young women is rare; so far, no case of an 18-year-old woman has been described. Here, we report a case with a T3 HPV 52-induced tumor 3 years after primary HPV contamination. CASE: An 18-year-old woman without risk factors complaining of dysuria and vulvar pain was treated several months for fungal infection before referred and diagnosed with a vulvar carcinoma located between clitoris and urethra. She underwent operation with partial urethral resection and external radiation. The tumor tested positive for HPV type 52, the time between primary sexual contact and tumor development was less than 3 years. CONCLUSION: Also in very young women, an ulcer and vulvar pain have to be biopsied to exclude malignancy despite an unusual short time interval between possible HPV contamination and symptoms.

Expression of death-associated protein kinase during tumour progression of human renal cell carcinomas: hypermethylation-independent mechanisms of inactivation.

Death-associated protein kinase (DAPK) is a pro-apoptotic Ca(2+)/calmodulin-dependent serine/threonine kinase that is widely expressed in tissues but kept silent in growing cells. Downregulation of DAPK transcription by CpG methylation has been demonstrated in a variety of tumours, providing a selective growth advantage during tumour progression. As the in vivo expression of DAPK in human renal cell carcinomas (RCCs) has not previously been analysed, 72 RCCs were investigated using semi-quantitative real-time reverse transcription polymerase chain reaction (RT-PCR). We found that almost 92% (66/72) of all primary RCCs express DAPK mRNA and results obtained from methylation-specific PCR analyses suggest that aberrant CpG methylation of the DAPK promoter is absent even in DAPK non-expressing tumours. Comparison of early/intermediate with advanced tumour stages of clear cell RCCs showed that no significant changes in the expression levels of DAPK were evident. Chromophilic/papillary RCCs display no significantly different expression patterns of DAPK compared with stage-adjusted clear cell RCCs. Furthermore, on analysing the DAPK enzyme activity in RCC cell lines with DAPK mRNA and protein expression, only 1 out of 11 cell lines showed basal DAPK activity in kinase activity assays, suggesting that DAPK, although expressed in RCC, remains largely inactive. Our study demonstrates the in vivo expression of DAPK in RCCs and reveals that, in contrast to other tumour types, RCCs may not downregulate DAPK mRNA expression during tumour progression. Despite persistent DAPK transcription and translation, however, the markedly reduced DAPK enzyme activity in our RCC cell lines suggested a post-translational inactivation of DAPK in RCCs.

XIAP expression is an independent prognostic marker in clear-cell renal carcinomas.

Deregulation of apoptosis plays an important role in carcinogenesis, tumor progression, and resistance to chemotherapy. XIAP is considered to be the most potent caspase inhibitor of all known IAP (inhibitor of apoptosis) family members. To explore the relevance of XIAP for progression and prognosis in renal cell carcinomas (RCCs) of the clear-cell type, we analyzed XIAP protein expression in formalin-fixed tissue from 145 clear-cell RCCs by immunohistochemistry. XIAP protein expression was found in 95% of clear-cell RCCs. A significant increase of XIAP expression became evident from well (G1) to poorly (G3) differentiated clear-cell RCCs (P < 0.0001) and from low (pT1) to advanced (pT3) tumor stages (P = 0.0016). Log-rank test showed a significant inverse correlation (P = 0.0174) between XIAP expression and tumor aggressiveness as indicated by patients' survival. Most important, multivariate Cox regression analysis revealed that XIAP expression is an independent prognostic parameter (P = 0.018) in clear-cell RCCs. Our results suggest an important role for XIAP-mediated inhibition of apoptosis during progression of clear-cell RCCs and introduce XIAP expression as a new independent prognostic marker in this tumor type.