Biomedical subjects

Axel Benner

Publications and source records attributed to Axel Benner.

At least 55 records · Page 3Linked to original sources

PubMed2004

Melanoma metastasis is associated with enhanced expression of the syntenin gene.

Primary cutaneous melanomas and melanoma metastases were examined for differential gene expression using subtractive suppression hybridization in a search for any genes associated with metastasis. Generating a subtracted library of candidate genes up-regulated in melanoma metastases, this library contained 8 different cDNAs, among them a cDNA fragment of the syntenin gene which was overexpressed in further independent melanoma resection specimens on cDNA Southern blots when compared to acquired melanocytic nevi from which melanomas are known to arise. Upon immunohistochemistry, the syntenin protein expression was detected in the cytoplasm of primary cutaneous melanomas and melanoma metastases. Melanoma metastases exhibited higher proportions of tumour cells positive for syntenin immunostaining in comparison to acquired melanocytic nevi or non-metastasizing primary melanomas which was statistically significant. In addition to melanoma, gastric cancer tissues exhibited a higher syntenin mRNA expression on a matched tumour/normal cDNA array than their normal counterparts which was statistically significant. Altogether, we here first describe the detection of the syntenin protein in resection specimens of melanocytic lesions. We conclude that melanoma metastasis is associated with increased expression of the syntenin gene which may participate in signal transduction and cell adhesion via the multifunctional protein-binding properties of its tandem PDZ domains.

Blotting, Northern↗

PubMed2004

Expression of the heat shock cognate protein HSP73 correlates with tumour thickness of primary melanomas and is enhanced in melanoma metastases.

Seeking to identify melanoma-associated genes by comparing gene expression in uncultured primary melanoma specimens with those in nevi, from which melanomas often are known to arise, we applied subtractive suppression hybridization. Generating a subtracted library of candidate genes up-regulated in primary melanomas, this library contained cDNA fragments of the genes encoding heat shock cognate protein (HSP73) and major histocompatibility complex (HLA-DR) which were overexpressed in further 19 independent melanoma resection specimens on cDNA Southern blots when compared to 19 acquired melanocytic nevi. Upon immunohistochemistry, HSP73 protein expression was detected in the cytoplasm of melanoma cells in primary tumours and metastases. In primary melanomas, the proportion of HSP73 protein expressing cells correlated with tumour thickness according to Breslow which was statistically significant. HSP73 immunostaining was stronger in melanoma metastases when compared with acquired melanocytic nevi which was statistically significant. In addition to melanoma, gastric and uterus cancer tissues exhibited higher HSP73 mRNA expression on a matched tumour/normal cDNA array than their normal counterparts which was statistically significant. Participating in the regulation of folding, assembly and degradation of proteins and protecting cellular proteins from the damage caused by cellular stress like hypoxia or changes in cellular pH, elevated HSP73 expression possibly confers proliferative advantage on melanoma cells.

Gene Expression Regulation, Neoplastic↗

PubMed2003

The prognostic impact of autologous stem cell transplantation in patients with chronic lymphocytic leukemia: a risk-matched analysis based on the VH gene mutational status.

To assess the therapeutic value of sequential high-dose therapy (SHDT) including autologous stem cell transplantation in chronic lymphocytic leukemia (CLL) we performed a risk-matched comparison between 66 patients who had undergone a uniform SHDT regimen and a database of 291 patients treated conventionally. Matching variables were age, Binet stage, IgVH (variable region of the immunoglobulin heavy chain) gene mutational status, and lymphocyte count. Forty-four pairs fully matched for all 4 variables were identified. Patient groups were well balanced for additional risk factors including adverse genomic abnormalities and CD38 expression. With an overall median follow-up time of 70 and 86 months, respectively, survival was significantly longer for the SHDT patients than for the conventionally treated patients when calculated from diagnosis (hazard ratio [HR] 0.39; P=.03 [log rank]) or from study entry (HR 0.32; P=.006). The benefit for the SHDT group remained significant when the analyses were restricted to those 58 patients who had an unmutated VH status. Cox regression analysis confirmed SHDT as independent favorable prognostic factor for survival from diagnosis (HR 0.38, P=.04) as well as from study entry (HR 0.38, P=.03). These data suggest a survival benefit for patients with poor-risk CLL receiving SHDT during the course of their disease.

Adult↗

PubMed2003

VH mutation status and VDJ rearrangement structure in mantle cell lymphoma: correlation with genomic aberrations, clinical characteristics, and outcome.

Immunoglobulin variable heavy chain gene (VH) mutation status and VDJ rearrangement structure were analyzed in 141 patients with mantle cell lymphoma (MCL) and correlated with biologic and clinical characteristics; 29% of the MCLs displayed mutated VH using a 98% germline homology cutoff. Striking differences occurred in the VH mutation subgroups with respect to the use of specific V genes. Rearrangements involving V4-34 and V3-21 were almost exclusively unmutated, whereas rearrangements using V4-59 and V3-23 were typically mutated. Significant association occurred between mutated VH with shorter CDR3 lengths and the use of JH4b. V3-21 and V4-59 were involved in highly characteristic rearrangements, implying that antigen specificity might have been involved in MCL development. There was no evidence for isotype switch recombination or Bcl-6 expression in any MCL. ZAP70 expression was not different in VH-mutated or -unmutated MCL. Although the deletions 11q- and 17p- showed a balanced distribution, an overrepresentation was observed for trisomies +3q, +8q, and tetraploidy in the VH-unmutated subgroup and +12q in the VH-mutated subgroup. Clinically, mutated VH was associated with a higher rate of complete remission, but there was no correlation between VH mutation status and other clinical characteristics or overall survival.

Chromosome Aberrations↗

PubMed2003

Pathogenesis of DNA repair-deficient cancers: a statistical meta-analysis of putative Real Common Target genes.

DNA mismatch repair deficiency is observed in about 15% of human colorectal, gastric, and endometrial tumors and in lower frequencies in a minority of other tumors thereby causing insertion/deletion mutations at short repetitive sequences, recognized as microsatellite instability (MSI). Evolution of tumors, including those with MSI, is a continuous process of mutation and selection favoring neoplastic growth. Mutations in microsatellite-bearing genes that promote tumor cell growth in general (Real Common Target genes) are assumed to be the driving force during MSI carcinogenesis. Thus, microsatellite mutations in these genes should occur more frequently than mutations in microsatellite genes without contribution to malignancy (ByStander genes). So far, only a few Real Common Target genes have been identified by functional studies. Thus, comprehensive analysis of microsatellite mutations will provide important clues to the understanding of MSI-driven carcinogenesis. Here, we evaluated published mutation frequencies on 194 repeat tracts in 137 genes in MSI-H colorectal, endometrial, and gastric carcinomas and propose a statistical model that aims to identify Real Common Target genes. According to our model nine genes including BAX and TGFbetaRII were identified as Real Common Targets in colorectal cancer, one gene in gastric cancer, and three genes in endometrial cancer. Microsatellite mutations in five additional genes seem to be counterselected in gastrointestinal tumors. Overall, the general applicability, the capacity to unlimited data analysis, the inclusion of mutation data generated by different groups on different sets of tumors make this model a useful tool for predicting Real Common Target genes with specificity for MSI-H tumors of different organs, guiding subsequent functional studies to the most likely targets among numerous microsatellite harboring genes.

Base Pair Mismatch↗

PubMed2003

Tissue microarray analysis reveals site-specific prevalence of oncogene amplifications in head and neck squamous cell carcinoma.

Fluorescence in situ hybridization was applied on a collection of 609 squamous cell carcinomas of the head and neck (HNSCCs),including 511 primary carcinomas of different clinical stage and anatomical localization and 98 recurrent carcinomas, second primary carcinomas, and regional metastases on a tissue microarray. The overall prevalence of amplifications of five oncogenes analyzed was 34.5% for CCND1, 12.7% for EGFR, 8.8% for MYC, 6.2% for ZNF217, and 3.6% for ERBB2. CCND1 amplifications were associated with the pharyngeal site in primary carcinomas (P < 0.001), whereas amplifications of ZNF217 were less frequent in pharyngeal carcinomas as compared with primary oral and laryngeal carcinomas (P = 0.02). The amplification pattern of these oncogenes suggests that different molecular pathways are involved in HNSCCs of different localizations.

Carcinoma, Squamous Cell↗

PubMed2003

Capillary electrophoretic analysis of genomic DNA methylation levels.

Changes in DNA methylation have been found in the large majority of tumors. This phenomenon includes both genome-wide hypomethylation and gene- specific hypermethylation. However, the clinical relevance of either mechanism has remained contentious. In order to determine DNA methylation levels from a large number of clinical samples, we have established a method for accurate high-throughput quantification of 5-methylcytosine in genomic DNA. Our protocol requires a small amount (<1 micro g) of DNA that is enzymatically hydrolyzed to single nucleotides. Single nucleotides are then derivatized with a fluorescent marker and separated by capillary electrophoresis. After calibration of the method, we have determined cytosine methylation levels from tumor samples of 81 patients that had been diagnosed with chronic lymphocytic leukemia (CLL). These patients showed a high variability in their methylation levels with a general trend towards hypomethylation. Because of its high accuracy and throughput our method will be useful in determining the role of genomic DNA methylation levels in tumorigenesis.

Cytosine↗

PubMed2003

Gene expression patterns in ependymomas correlate with tumor location, grade, and patient age.

To elucidate the molecular events responsible for tumorigenesis and progression of ependymomas, we analyzed molecular alterations on the gene expression level in a series of newly diagnosed ependymal neoplasms (n = 39). To this aim, tumor RNA was hybridized to microarrays comprising 2600 different genes with relevance to mitosis, cell-cycle control, oncogenesis, or apoptosis. For CLU, IGF-2, and RAF-1, which are apparent candidate genes because they had been previously described to be involved in tumorigenesis of other human malignancies, we found a high expression on the mRNA as well as the protein level. We identified gene expression signatures for the differentiation of tumors with respect to location, grade, and patient age. Spinal ependymomas were characterized by high-expression levels of HOXB5, PLA2G, and CDKN2A and tumors in young patients (< or =16 years of age) by high-expression levels of LDHB and STAM. Notably, we were able to classify supratentorial grade II and III tumors with 100% accuracy, whereas this did not apply for infratentorial ependymomas. The similar gene expression patterns of grade II and III infratentorial malignancies suggest that grade III tumors may develop through a secondary multistep transformation process involving genes that are related to cell proliferation (LDHA, cyclin B, MAT2A) or tumor suppression (PTEN). In summary, our results provide new insight in the biochemical pathways particularly intriguing in the pathomechanism of ependymomas and suggest that this entity comprises molecularly distinct diseases.

Adolescent↗

PubMed2003

Personal characteristics, therapy modalities and individual DNA repair capacity as predictive factors of acute skin toxicity in an unselected cohort of breast cancer patients receiving radiotherapy.

BACKGROUND AND PURPOSE: Intrinsic and extrinsic factors can affect the occurrence of side effects of radiotherapy. The influence of therapy modalities, personal characteristics and individual DNA repair capacity on the risk of acute skin toxicity was thus evaluated. MATERIALS AND METHODS: In a prospective study of 478 female breast cancer patients receiving adjuvant radiotherapy of the breast after breast-conserving surgery, acute skin toxicity was documented systematically using a modified version of the common toxicity criteria. Prognostic personal and treatment characteristics were identified for the entire cohort. Individual DNA repair capacity was determined in a subgroup of 113 patients with alkaline comet assay using phytohemagglutinin stimulated lymphocytes. Using proportional hazards analysis to account for cumulative biologically effective radiation dose, the hazard for the development of acute skin reactions (moist desquamation) associated with DNA repair capacity was modeled. RESULTS: Of the 478 participants, 84 presented with acute reactions by the end of treatment. Higher body mass index was significantly associated with an increased risk for acute reactions (hazard ratio=1.09 per 1 kg/m(2)), adjusted for treating hospital and photon beam quality. The comet assay parameters examined, including background DNA damage in non-irradiated cells, DNA damage induced by 5 Gy, and DNA repair capacity, were not significantly associated with risk of acute skin toxicity. CONCLUSIONS: Higher BMI is predictive of acute skin toxicity, however, individual repair parameters as determined by the alkaline comet assay are not informative enough. More comprehensive analyses including late effects of radiotherapy and repair kinetics optimized for different radiation-induced DNA lesions are warranted.

Breast Neoplasms↗

PubMed2003

Biofeedback versus electrostimulation in treatment of anal sphincter insufficiency.

The purpose of this study was to prospectively investigate a consecutive patient series (N = 70) with anal sphincter insufficiency and compare the efficacy of biofeedback and electrostimulation as conservative treatment options. Forty patients were treated by biofeedback training, 30 patients by electrostimulation. Patients were not specifically selected for one or the other treatment. Success was evaluated by vector volume manometry, water infusion test, time until stoma closure and clinical incontinence scores. Resting and squeeze pressure and resting and squeeze vector volume all increased significantly after biofeedback training (P < 0.05 and < 0.001). Resting pressure and squeeze vector volume only were significantly improved by electrostimulation (P < 0.05 and < 0.01). The increase in squeeze vector volume was significantly greater in the biofeedback group (P = 0.03). The estimated median time period from commencement of training until stoma closure was 9 months in the biofeedback versus 21 months in the electrostimulation group. Biofeedback training is probably superior to electrostimulation in the conservative treatment of anal sphincter insufficiency, this needs to be confirmed in a randomized study.

Adolescent↗

PubMed2003

Addition of a low fixed number of CD3+ cells to CD34-enriched allografts: effects on engraftment, graft-versus-host disease, and survival after related and unrelated peripheral stem cell transplantation.

Despite prophylaxis with immunosuppressive drugs, severe graft-versus-host disease (GVHD) remains a major cause of morbidity and mortality following allogeneic stem cell transplantation. T cell depletion of the graft has decreased incidence and severity of GVHD but has resulted in a higher incidence of graft failure and relapse. To reduce the risk of severe GVHD, but at the same time to maintain the graft-versus-tumor effect, we administered a fixed low number of 1 x 10(5) donor T cells per kilogram of body weight to recipients of CD34(+) cell-enriched allogeneic peripheral blood stem cells (PBSCs). Donor lymphocyte infusions (DLI) were then given in incremental doses when mixed chimerism persisted or signs of relapse occurred. A total of 23 patients receiving allografts from related and unrelated donors were treated according to this protocol after myeloablative or reduced intensity conditioning. One patient did not engraft and 3/20 evaluable patients developed acute (a) GVHD > or = grade II, with a corresponding estimated cumulative incidence of 15.6% (95% CI 0-30.5%). DLI (n = 13) induced aGVHD > or = II in 6 patients, but the severity of the syndrome was reduced. Overall GVHD-related mortality was low (13%). The probability of disease-free survival and overall survival at 2 years was 0.40 (95% CI 0.21-0.75) and 0.36 (95% CI 0.21-0.63). Progression-free survival and overall survival was significantly better in patients with acute or chronic myelogenous leukemia compared to patients with lymphoproliferative disorders (p = 0.002; p = 0.02). We conclude that the combination of allografts with a T cell content of about 1 x 10(5)/kg and escalating doses of DLI is a viable transplant strategy in patients with myeloid leukemias, which results in stable engraftment and a reduction of mortality from aGVHD.

Adult↗

PubMed2003

Unrelated donor transplantation after reduced intensity conditioning as an approach for patients lacking related donors for allogeneic stem cell transplantation.

Allogeneic stem cell transplantation (SCT) after reduced intensity conditioning (RIC) provides a new curative treatment option for patients usually not eligible for allogeneic SCT. Because the majority of patients lack HLA-identical sibling donors (SD), unrelated donor (UD) transplantation is performed increasingly. In this retrospective analysis, we have reviewed our experience with reduced-intensity conditioning regimens, comparing related and unrelated donors. From November, 1997, to February, 2002, 51 patients with hematological malignancies received allogeneic SCT after various RIC regimens. A total of 31 had a related donor, and the remaining 20 had an unrelated donor (UD). Both groups were comparable with respect to age and gender. We observed a trend toward higher rate of graft failure in the unrelated donor group with 11% compared to 3% in the related donor group (p = 0.55). The rate of acute graft-versus-host disease (GVHD) II-IV was 36% in the RD group versus 44% for the UD group; severe GVHD III-IV occurred in 26% and 22%, respectively. There were more serious infections in the unrelated donor group with 25% compared to 16%. Transplant-related mortality was 13% (RD group) versus 30% (UD group). At 21 months, progression-free survival was 30% in both groups. The Kaplan Meier estimate of overall survival was 40% (RD) and 30% (UD group). In summary, we found no statistically significant difference regarding progression free and overall survival, despite a trend for more graft failure and increased transplant-related complications associated with the use of stem cells from unrelated donors.

Adult↗

PubMed2003

Decreased detection rate of disseminated tumor cells of rectal cancer patients after preoperative chemoradiation: a first step towards a molecular surrogate marker for neoadjuvant treatment in colorectal cancer.

OBJECTIVE: To compare the detection rates for rectal cancer cells in blood and bone marrow in patients with or without preoperative chemoradiation. SUMMARY BACKGROUND DATA: Previous reports have postulated a resistance of disseminated tumor cells to antiproliferative agents because of tumor cell dormancy. METHODS: Blood samples from 142 patients (pre, intra-, and postoperative samples) and bone marrow samples from 127 patients undergoing resection of rectal adenocarcinoma were analyzed for tumor cells using a cytokeratin (CK) 20-reverse transcription polymerase chain reaction. The results were stratified according to preoperative therapy. RESULTS: In patients without preoperative chemoradiation, tumor cell detection in blood and bone marrow correlated to tumor stage (Cochran Armitage trend test, P < 0.05). Tumor cells were detected in 34 of 103 (33%) bone marrow and 65 of 117 (55.6%) blood samples of patients without neoadjuvant treatment versus in 4 of 24 (16.7%) bone marrow and in 10 of 25 (40%) blood samples of patients with neoadjuvant treatment. The tumor cell detection rate was significantly lower in the group having undergone chemoradiation (binary logistic regression analysis, P < 0.05). The overall and disease-free survival were significantly worse in patients with tumor cell detection in the bone marrow after neoadjuvant therapy. CONCLUSIONS: Preoperative chemoradiation is associated with a decreased detection rate of rectal cancer cells in blood and bone marrow. These findings may explain the observed clinical benefit of patients with rectal cancer receiving chemoradiation. This is the first study suggesting that detection of disseminated rectal cancer cells may be useful for assessing the efficacy of neoadjuvant therapy.

Adenocarcinoma↗

PubMed2002

Retroviral vector integration occurs in preferred genomic targets of human bone marrow-repopulating cells.

Increasing use of hematopoietic stem cells for retroviral vector-mediated gene therapy and recent reports on insertional mutagenesis in mice and humans have created intense interest to characterize vector integrations on a genomic level. We studied retrovirally transduced human peripheral blood progenitor cells with bone marrow-repopulating ability in immune-deficient mice. By using a highly sensitive and specific ligation-mediated polymerase chain reaction (PCR) followed by sequencing of vector integration sites, we found a multitude of simultaneously active human stem cell clones 8 weeks after transplantation. Vector integrations occurred with significantly increased frequency into chromosomes 17 and 19 and into specific regions of chromosomes 6, 13, and 16, although most of the chromosomes were targeted. Preferred genomic target sites have previously only been reported for wild-type retroviruses. Our findings reveal for the first time that retroviral vector integration into human marrow-repopulating cells can be nonrandom (P =.000 37).

Animals↗

PubMed2002

V(H) mutation status, CD38 expression level, genomic aberrations, and survival in chronic lymphocytic leukemia.

In chronic lymphocytic leukemia (CLL), biologic risk factors such as immunoglobulin variable heavy chain gene (V(H)) mutation status, CD38 expression level, and genomic aberrations have recently been identified, but the relative prognostic impact of the individual parameters is unknown. In the current study, we analyzed V(H) mutation status by polymerase chain reaction and sequencing (n = 300), genomic aberrations by fluorescence in situ hybridization (+3q, 6q-, +8q, 11q-, +12q, 13q-, t(14q), 17p-) (n = 300), and CD38 expression by triple-color FACS (CD5, CD19, CD38) (n = 157) in a unicentric CLL cohort. The prognostic influence of V(H) mutation rate and CD38 expression level was tested by maximally selected log-rank statistics. A corrected P value (P(cor)) for a cutoff level allowing the best separation of 2 subgroups with different survival probabilities was identified at 97% V(H) homology (95% confidence interval [CI], 96%-98% homology, P(cor) <.001) and at 7% CD38 expression (95% CI, 20%-71% expression, P(cor) =.02). In univariate analyses, unmutated V(H) genes and high CD38 expression levels predicted for shorter survival times. The overall incidence of genomic aberrations was similar in the V(H) unmutated and V(H) mutated subgroups. High-risk genomic aberrations such as 17p- and 11q- occurred almost exclusively in the V(H) unmutated subgroup, whereas favorable aberrations such as 13q- and 13q- as single abnormalities were overrepresented in the V(H) mutated subgroup. In multivariate analysis, unmutated V(H), 17p deletion, 11q deletion, age, WBC, and LDH were identified as independent prognostic factors, indicating a complementary role of V(H) mutation status and genomic aberrations to predict outcome in CLL.

ADP-ribosyl Cyclase↗

PubMed2002

Prognostic significance of activating FLT3 mutations in younger adults (16 to 60 years) with acute myeloid leukemia and normal cytogenetics: a study of the AML Study Group Ulm.

To assess the prognostic relevance of activating mutations of the FLT3 gene in homogeneously treated adults 16 to 60 years of age with acute myeloid leukemia (AML) and normal cytogenetics, pretreatment samples from 224 patients entered into 2 consecutive multicenter treatment trials were analyzed for FLT3 internal tandem duplications (ITDs) and Asp835 mutations. Treatment included intensive double-induction therapy and postremission therapy with high cumulative doses of high-dose cytarabine. ITDs were detected in 32% of the patients and were related to de novo AML and to high white blood cell (WBC) counts, percentages of peripheral blood (PB) and bone marrow (BM) blasts, and serum lactate dehydrogenase levels. Asp835 mutations were present in 14% of the patients and were associated with WBC counts and percentages of PB and BM blasts that were higher than those of patients without FLT3 mutations. With a median follow-up of 34 months, remission duration and overall survival (OS) were significantly shorter for patients with Asp835 mutations or an ITD than for those without FLT3 mutations (P =.03 and P =.0004, respectively). These results were attributable mainly to the negative prognostic effect of FLT3 ITDs. On multivariate analysis, mutant FLT3 was an independent marker affecting remission duration and OS (hazard ratio, 2.35 and 2.11, respectively). Fluorescence in situ hybridization did not detect monoallelic FLT3 deletions in ITD-positive patients. FLT3 mutations identify a subset of young AML patients with normal cytogenetics who do not benefit from intensive chemotherapy, including double-induction and postremission therapy with high-dose cytarabine.

Acute Disease↗

PubMed2002

Prognostic significance of partial tandem duplications of the MLL gene in adult patients 16 to 60 years old with acute myeloid leukemia and normal cytogenetics: a study of the Acute Myeloid Leukemia Study Group Ulm.

PURPOSE: To evaluate the incidence and clinical significance of partial tandem duplications (PTDs) of the mixed lineage leukemia (MLL) gene in a large series of newly diagnosed adult patients (16 to 60 years old) with acute myeloid leukemia (AML) intensively treated within the multicenter treatment trials AML-HD93 and AML-HD98A. PATIENTS AND METHODS: Identification of MLL PTD was performed centrally using Southern blot analysis in pretreatment samples from 525 of 683 assessable patients. PTD was confirmed by polymerase chain reaction (PCR) and sequencing of the PCR products. RESULTS: MLL PTD was identified in none of the 129 patients with t(8;21), inv(16), and t(15;17); in 19 (7.7%) of 247 patients with normal karyotype; and in 10 (8.5%) of 119 patients with all other abnormalities, with 30 cases of t(11q23) excluded. In the group of patients with a normal karyotype, there was no difference in the presenting clinical features between the PTD-positive and the PTD-negative cases. Sixteen (89%) of the 18 assessable PTD-positive patients and 158 (78%) of the 203 PTD-negative patients achieved a complete remission. After a median follow-up time of 19 months, 11 of the 16 PTD-positive patients relapsed compared with 54 of the 158 PTD-negative patients; the median remission durations of the PTD-positive and the PTD-negative groups were 7.75 months and 19 months, respectively (P <.001). Multivariate analysis identified the MLL PTD status as the single prognostic factor for remission duration. CONCLUSION: Within the subgroup of young adult AML patients with normal karyotype, MLL PTD is associated with short remission duration.

Adolescent↗

PubMed2002

Basal transcription activity of the dyskeratosis congenita gene is mediated by Sp1 and Sp3 and a patient mutation in a Sp1 binding site is associated with decreased promoter activity.

The multisystem disorder dyskeratosis congenita (DKC) is caused by mutations in the DKC1 gene. The protein dyskerin is a component of the box H+ACA small nucleolar RNAs (snoRNAs) and is also functionally associated with the RNA component of the human telomerase. The majority of mutations are missense mutations, although single examples of non-coding mutations have been described. One of these is a point mutation in a putative Sp1 binding site in the 5'-upstream region of the DKC1 gene which presumably represents the promoter region of the gene. In this report, we compare the promoter sequences of both the human and mouse genes and provide a first functional characterisation of the human DKC1 promoter. This includes a characterisation of the disease-associated implications caused by the mutation identified in one patient. By reporter gene analysis, functional regions of the DKC1 promoter were delineated. The core promoter region critical for basal level of transcription was found to lie at -10 to -180. Bandshift- and supershift experiments clearly demonstrated a mutual binding of transcription factors Sp1 and Sp3 to two of five putative GC-box/Sp1-binding sites located within the core promoter region. An additional GC-box interacts only with the Sp1 transcription factor. Further, we provide evidence that the DKC1 mutation in one of the Sp1 binding sites results in reduced promoter activity.

5' Flanking Region↗