Biomedical subjects

Rainald Knecht

Publications and source records attributed to Rainald Knecht.

At least 19 recordsLinked to original sources

PubMed2007

Usefulness of MRI volumetric evaluation in patients with squamous cell cancer of the head and neck treated with neoadjuvant chemotherapy.

BACKGROUND: The purpose was to evaluate the efficacy of tumor volumetry on MRI as predictive of response to treatment with induction chemotherapy, comparing the results with endoscopy. METHODS: Fifty patients with advanced squamous cell carcinoma of the head and neck (SSCHN) who underwent MRI volumetry before and after neoadjuvant chemotherapy consisting of docetaxel, cisplatin, and 5-fluorouracil (TPF) were included in this study. The tumor volume was calculated by a slice-by-slice evaluation. With the standard software of a workstation, the area of the tumor was measured slice by slice using manual segmentation. To evaluate the efficacy of MRI volumetry, pretreatment volume was compared with pretreatment remission status as evaluated with endoscopy. RESULTS: Forty-five (90%) patients demonstrated a tumor downstaging after chemotherapy. Fourteen (28%) patients showed a complete histologic remission (CR), 31 (62%) patients showed a partial remission (PR). Pretreatment tumor volume was significantly different between patients whose tumor completely responded (CR) and those whose tumor did not completely respond or whose disease was stable or was progressive (p = .00023). We defined a threshold for the pretreatment tumor volume in patients with CR, which was equal to 29.71 cc. CONCLUSION: We propose that MRI tumor volume analyses can be a useful parameter to predict the response to neoadjuvant chemotherapy in SCCHN.

Adult↗

PubMed2007

Inverse correlation between serum PGE2 and T classification in head and neck cancer.

BACKGROUND: Prostaglandin E2 (PGE2) serum levels have been shown previously to be increased in tumor bearing mice as well as in patients with solid tumors; however, the impact on the course or stage of disease has not been shown. We hypothesized that PGE2 is strictly required for aggressive and especially early-stage tumors of the head and neck to provoke invasion and angiogenesis. METHODS: We analyzed the serum PGE2 levels of 100 patients with head and neck squamous cell carcinoma of different stages before and 1 year after treatment and compared the results with the serum levels of 40 healthy donors and the secretion profile of 8 different squamous cell carcinoma cell lines. RESULTS: Our investigations showed a statistically significant inverse correlation between PGE2 serum levels and tumor stage. Furthermore, this effect has been reflected by the results of our cell culture analyses, which showed an inversely regulated PGE2 secretion into the medium during the process of proliferation. Interestingly, the serum levels of PGE2 were significantly downregulated 1 year after successful treatment. CONCLUSIONS: We conclude that PGE2 serum level as an indicator for early-stage cancer of the head and neck may function as a tumor marker during the follow-up period.

Biomarkers, Tumor↗

PubMed2006

Pituitary tumor-transforming gene expression is a prognostic marker for tumor recurrence in squamous cell carcinoma of the head and neck.

BACKGROUND: The proto-oncogene pituitary tumor-transforming gene (PTTG) has been shown to be abundantly overexpressed in a large variety of neoplasms likely promoting neo-vascularization and tumor invasiveness. In this study, we investigated a potential role for PTTG mRNA expression as a marker to evaluate the future clinical outcome of patients diagnosed with primary cancer of the head and neck. METHODS: Tumor samples derived from primary tumors of 89 patients suffering from a squamous cell carcinoma were analyzed for PTTG mRNA-expression and compared to corresponding unaffected tissue. Expression levels were correlated to standard clinico-pathological parameters based on a five year observation period. RESULTS: In almost all 89 tumor samples PTTG was found to be overexpressed (median fold increase: 2.1) when compared to the unaffected tissue specimens derived from the same patient. The nodal stage correlated with PTTG transcript levels with significant differences between pN0 (median expression: 1.32) and pN+ (median expression: 2.12; P = 0.016). In patients who developed a tumor recurrence we detected a significantly higher PTTG expression in primary tumors (median expression: 2.63) when compared to patients who did not develop a tumor recurrence (median expression: 1.29; P = 0.009). Since the median expression of PTTG in patients with tumor stage T1/2N0M0 that received surgery alone without tumor recurrence was 0.94 versus 3.82 in patients suffering from a tumor recurrence (P = 0.006), PTTG expression might provide a feasible mean of predicting tumor recurrence. CONCLUSION: Elevated PTTG transcript levels might be used as a prognostic biomarker for future clinical outcome (i.e. recurrence) in primary squamous cell carcinomas of the head and neck, especially in early stages of tumor development.

Adult↗

PubMed2006

In vivo proton MR spectroscopy of primary tumours, nodal and recurrent disease of the extracranial head and neck.

Benign and malignant neoplasms as well as metastatic lymph nodes of 39 patients were examined using localized single voxel magnetic resonance spectroscopy (MRS) [repetition time (TR) 1500, echo time (TE) 135) at 1.5 T. New techniques with simultaneous correction of motion artefacts during the acquisition, three-dimensional saturation pulses, respiratory triggering and smaller volume of interest (VOI) size, were applied. Ratios of peak areas under the choline (Cho) and creatine (Cr) resonances were estimated in all cases and compared with those from samples of normal tissue. Ninety one spectra were acquired in 39 patients, 63 of which were suitable for further evaluation. The smallest VOI was 0.40 cm(3). The Cho/Cr ratios in all malignant neoplasms (mean: 5.2, range: 1.7-17.8) were significantly elevated relative to those in the normal muscle structures (mean: 0.9, range: 0.2-1.4), while those in the benign neoplasms were elevated (mean: 24.4, range: 1.4-59.7) with respect to those in the malignant ones. The average Cho/Cr ratio in the metastatic lymph nodes was significantly higher (mean: 4.8, range: 3.3-5.6) than that for benign lymphoid hyperplasia (mean: 2.2, range: 1.0-3.0). MRS measurements were able to differentiate recurrent disease from post-therapeutic tissue changes in 11 out of 13 patients.

Adult↗

PubMed2006

AdOnco: a database for clinical and scientific documentation of head and neck oncology.

OBJECTIVES: The aim of this project was to design, develop, and implement a head and neck cancer computer database for clinical and scientific use. METHODS: A relational database based on Filemaker Pro 6.0 was developed and integrated into our local network. A precise and easy-to-handle interface should allow for a quick overview of the patient's oncological history and for optimized data acquisition. An automatic report function was integrated to enhance the quality of daily patient care. For evaluation purposes, statistical analysis functions were implemented. RESULTS: Over a 14-month period, 410 patient records were available through the local network. The automated report function and the well-organized screen desktop resulted in time-efficient and accurate patient care. Additionally, the quality of information presented to referring physicians increased notably. The statistical analysis data provided by the database were reliable and easy to export. CONCLUSIONS: We developed an oncology database for both clinical and scientific purposes and integrated it successfully into our patient documentation system. The combination of clinical and scientific features proved to be very effective in daily routine and research.

Algorithms↗

PubMed2005

Patient-based cross-platform comparison of oligonucleotide microarray expression profiles.

The comparison of gene expression measurements obtained with different technical approaches is of substantial interest in order to clarify whether inter-platform differences may conceal biologically significant information. To address this concern, we analyzed gene expression in a set of head and neck squamous cell carcinoma patients, using both spotted oligonucleotide microarrays made from a large collection of 70-mer probes and commercial arrays produced by in situ synthesis of sets of multiple 25-mer oligonucleotides per gene. Expression measurements were compared for 4425 genes represented on both platforms, which revealed strong correlations between the corresponding data sets. Of note, a global tendency towards smaller absolute ratios was observed when using the 70-mer probes. Real-time quantitative reverse transcription PCR measurements were conducted to verify expression ratios for a subset of genes and achieved good agreement regarding both array platforms. In conclusion, similar profiles of relative gene expression were obtained using arrays of either single 70-mer or multiple short 25-mer oligonucleotide probes per gene. Although qualitative assessments of the expression of individual genes have to be made with caution, our results indicate that the comparison of gene expression profiles generated on these platforms will help to discover disease-related gene signatures in general.

Base Sequence↗

PubMed2005

EGFR-antibody-supplemented TPF chemotherapy. Preclinical investigations to a novel approach for head and neck cancer induction treatment.

Recent studies on polychemotherapy of head and neck cancer showed an improved remission rate on adding taxanes to the standard cytotoxic drugs cisplatin and 5-fluorouracil (5-FU). Moreover, for enhancing the response rate of chemotherapy today, a series of biological response modifiers are of interest, including modulators of the epidermal growth factor receptor (EGFR). Therefore we investigated whether the addition of monoclonal antibodies against the EGFR could enhance the response rate of cisplatin, 5-FU and docetaxel. Squamous cell cancer lines were transplanted into nude mice. After tumors had begun to grow, they were treated either with cisplatin, 5-FU or docetaxel alone or in combination with escalating doses of a humanized monoclonal anti-EGFR antibody.

Animals↗

PubMed2004

Cancer inhibition in nude mice after systemic application of U6 promoter-driven short hairpin RNAs against PLK1.

BACKGROUND: RNA interference initiated by small interfering RNAs effectively suppresses gene expression, but the suppression is transient, which limits the therapeutic use of this technique. Polo-like kinase 1 (PLK1) is a key cell cycle regulator that is overexpressed in various human tumors. We used a xenograft mouse model to determine whether an RNA interference-based strategy that used short hairpin RNAs (shRNAs) to suppress PLK1 expression could inhibit tumor growth in vivo. METHODS: HeLa S3 cervical and A549 lung cancer cell lines were transfected with plasmids containing U6 promoter-driven shRNAs against human PLK1 or control (parental or scrambled) plasmids. Plasmids were treated with the nuclease inhibitor aurintricarboxylic acid (ATA) as protection against nucleases in murine blood. Nude mice carrying xenograft tumors were injected with shRNA plasmids, and their xenograft tumor growth was assessed. Northern and western blot analyses were used to measure PLK1 mRNA and protein expression, respectively, in transfected cultured cells and in xenograft tumors. All statistical tests were two-sided. RESULTS: Levels of PLK1 mRNA and protein were lower in HeLa S3 and A549 cancer cells transfected with PLK1 shRNA plasmids than in corresponding cells transfected with control parental or scrambled PLK1S shRNA plasmids. Proliferation of cells transfected with PLK1 shRNA was lower than that of cells transfected with either control plasmid, and proliferation of cells transfected with ATA-treated PLK1 shRNA plasmids was even lower. In mice with human xenograft tumors, PLK1 shRNA expression from ATA-treated plasmids reduced tumor growth to 18% (95% confidence interval [CI] = 12% to 26%; P =.03) and from untreated plasmids reduced tumor growth to 45% (95% CI = 26% to 64%; P =.1) of that of tumors in mice treated with scrambled control PLK1S shRNA plasmids. CONCLUSIONS: The combination of shRNA-mediated gene silencing with effective in vivo gene delivery strategies appears to generate a long-lasting silencing signal.

Actins↗

PubMed2003

Expression of hypoxia inducible factor 1 alpha and Von Hippel Lindau protein in human middle ear cholesteatoma.

OBJECTIVE: To evaluate the role of hypoxia in cholesteatoma progression. STUDY DESIGN: Immunohistochemical analysis of paraffin-embedded human specimens. METHODS: Thirteen middle ear cholesteatomas and 10 samples of normal human external ear canal skin were stained immunohistochemically for the presence of hypoxia inducible factor 1 alpha (HIF 1 alpha) and Von Hippel Lindau protein. Specimens were then analyzed semiquantitatively. RESULTS: Staining for both antibodies could be detected in all cholesteatomas (perimatrix and matrix), as well as in the samples of normal human ear canal skin. Cholesteatoma specimens showed statistically significant increased staining when compared with normal human skin and mucosa. The age of patients and relapse surgery affected immunohistochemical staining of HIF 1 alpha and Von Hippel Lindau protein. CONCLUSIONS: Elevated staining intensities for HIF 1 alpha and Von Hippel Lindau protein in cholesteatoma tissue indicated that cholesteatoma may be hypoxic. In addition, our data indicated that relapse cholesteatomas yield a higher degree of hypoxia than ears without surgery.

Adolescent↗

PubMed2002

Anti-epidermal growth factor receptor-antibody therapy for treatment of breast cancer.

Recent studies demonstrated that tumors overexpressing the epidermal growth factor receptor (EGF-R, erbB-1) are associated with poor clinical outcome. This led to the development of a variety of monoclonal antibodies targeting the extracellular domain of this receptor tyrosine kinase. The aim of our study was the evaluation of anti-EGF-R antibody EMD 55900 therapy for treatment of breast cancer. On the basis of 299 tumor specimens derived from breast cancer patients, we investigated EGF-R expression and generated a collective of primary xenotransplants in athymic nude mice. The animals received therapy in 2 treatment schedules to investigate the therapeutic response in early stages of tumor formation as well as on well established tumors. Using 6 different tumors with EGF-R expression levels between 10-300 fmol/mg total protein, we found a therapeutic effect when the EGF-R expression of the tumors was at least 40 fMol/mg. On the basis of these experimental data and our EGF-R expression analysis of breast cancer specimens, we conclude that up to 15% of breast cancer patients could benefit from this monotherapy with EMD 55900.

Animals↗

PubMed2002

Modulation of tamoxifen-induced apoptosis by peripheral benzodiazepine receptor ligands in breast cancer cells.

The peripheral benzodiazepine receptor (PBR), an integral protein of the mitochondrial membrane, is involved in the formation of mitochondrial permeability transition (MPT) pores. The opening of the MPT-leading to the dissipation of the inner-mitochondrial transmembrane potential (deltapsi(m))-is considered to be an early apoptotic event. Therefore, we investigated the effect of the high-affinity PBR ligands Ro5-4684 and PK 11195 on tamoxifen (TAM)-induced apoptosis in MCF-7 and BT-20 breast cancer cell lines. Application of 100 nM TAM led to induction of apoptosis in both cell lines. Estrogene receptor (ER)-positive MCF-7 cells arrested in G(2/M) by TAM treatment showed no general dissipation of deltapsi(m), but reduction of deltapsi(m) was observed in a population of cells with high deltapsi(m). In ER-negative BT-20 cells TAM treatment induced no arrest of the cell cycle but dissipation of deltapsi(m). In both cell lines, nanomolar concentrations of the PBR ligands, which showed minor pro-apoptotic action themselves, reduced TAM-induced decrease of deltapsi(m) and apoptosis. In MCF-7 cells, a reduction of bcl-2 protein expression by TAM treatment was abolished by a combination of TAM with PBR ligands. Bax protein expression in BT-20 cells showed a significant increase in TAM-treated cells after 24hr but was not increased when treated with TAM and PBR ligands. From these findings, we concluded that binding of PBR ligands in nanomolar concentrations protects cells against apoptosis.

Antineoplastic Agents, Hormonal↗

PubMed2002

Downregulation of human polo-like kinase activity by antisense oligonucleotides induces growth inhibition in cancer cells.

A central role for polo-like kinases (PLK) in regulating several stages of mitotic progression has been born out in several species. Overexpression of PLK1 is observed in the majority of hitherto analysed human tumors. PLK1 overexpression is a negative prognostic factor in patients suffering from non-small cell lung cancer, head and neck tumors, esophageal carcinomas and melanomas. In order to define the role of PLK1 for mitotic progression of human cells and for neoplastic cell growth, phosphorothioate antisense oligonucleotides (ASOs) were tested to selectively downregulate PLK1 expression in MDA-MB-435 (breast cancer), HeLa S3 (cervical carcinoma) and A549 (non-small cell lung cancer) cells. ASOs were identified which suppress PLK1 mRNA and protein in a dose-dependent and sequence-specific manner. This approach also led to reduced PLK1 serine/threonine kinase activity. Downregulation of cellular PLK1 levels in cancer cells altered cell cycle progression moderately with an elevated percentage (20-30%) of cells in G(2)/M. Furthermore, cells with reduced PLK1 protein gained a rounded phenotype with multiple centrosomes. Moreover, ASO treatment resulted in potent antiproliferative effects in cell culture. Considerable antitumor activity was observed in vivo against A549 cells. This study suggests that antisense inhibitors targeted against PLK1 at well tolerated doses may be considered as a cancer therapeutic agent.

Adenocarcinoma↗

PubMedDate not supplied

Antitumor effect of MAb EMD 55900 depends on EGF-R expression and histopathology.

The proliferative stimulus of the epidermal growth factor (EGF) in human epithelial cells is mediated by its binding to the external domain of the EGF receptor (EGF-R). The purpose of this study was to investigate whether growth arrest of tumors treated with anti-EGF-R MAb (EMD 55900) was dependent on EGF-R expression and distinct histopathologic criteria of those neoplasms. Nine different adenocarcinomas, squamous cell carcinomas and two neoplastic epithelial cell lines (A431 and Detroit 562), which were characterized by high EGF-R expression, were xenotransplanted onto NMRI-nu/nu mice and treated with an anti-EGF-R antibody (EMD 55900). Results revealed that EGF-R expression and distinct histopathologic growth patterns play an important role for the therapeutic effect of the EGF-R antibody treatment. Tumors with high epithelial cellularity and little connective tissue responded to EMD 55900 treatment to a greater degree of growth reduction than tumors with lower cellularity. These results will be helpful for evaluation of patients who would benefit from tumor therapy with anti-EGF-R antibody.

Adenocarcinoma↗

PubMedDate not supplied

EGFR antibody-supplemented TPE-chemotherapy. Preclinical investigations to a novel approach for head and neck cancer induction treatment.

Recent studies on polychemotherapy of head and neck cancer have shown an improved remission rate on adding taxanes to the standard cytotoxic drugs cisplatin and 5-fluorouracil (5-FU). Moreover, for enhancing the response rate of chemotherapy today, a series of biological response modifiers are of interest including modulators of the epidermal growth factor receptor (EGFR). Therefore we investigated whether the addition of monoclonal antibodies against the EGFR could enhance the response rate of cisplatin, 5-FU and docetaxel. Squamous cell cancer lines were transplated on nude mice. After tumors had begun to grow, they were treated either with cisplatin, 5-FU and docetaxel alone or in combination with escalating doses of a humanized monoclonal anti-EGFR antibody. Comparing with controls, docetaxel alone as well as the combination of docetaxel, cisplatin and 5-FU resulted in a significant tumor growth delay. The antibody alone also slowed down the tumor growth significantly at each concentration. Nevertheless, neither chemotherapy agents nor antibody alone yielded complete tumor remissions over an observation period up to 6 weeks. Only the combination of cisplatin, 5-FU, docetaxel and the antibody resulted in highly significant complete tumor remissions. Therefore we can show for the first time that the effect of TPF, which is now used as a novel Phase II protocol for induction chemotherapy in head and neck cancer, could be highly significantly enhanced through the addition of anti-EGFR antibodies. Because we did not observe an increased toxicity in the animal experiments, TPF/anti-EGFR therapy may define a new strategy in the induction treatment of head and neck carcinomas.

Animals↗

PubMedDate not supplied

STAT 3 activation in head and neck squamous cell carcinomas is controlled by the EGFR.

Proliferation of squamous cell carcinoma of the head and neck (SCCHN) depends on epidermal growth factor receptor (EGFR) expression. As STAT 3 activation as well contributes to the cell growth in SCCHN, the interaction of STAT 3 and the EGFR is of great interest when considering treatment options through inhibition of STAT 3. We, therefore, evaluated the influence of blocking or activating the EGFR in human SCCHN cell lines and in vivo tumors on STAT 3 activation. We compared the effects on STAT 3 activation with the regulation of MAP Kinase under these conditions. We found that STAT 3 can be strongly inhibited via EGFR blocking in vitro as well as in vivo. However, the influence of EGFR regulation on the MAP Kinase pathway seemed to be very slight. These findings provide evidence that STAT 3 signal activity in head and neck carcinomas, which is partially responsible for proliferative activity, can be controlled via the EGFR.

Animals↗

PubMedDate not supplied

Pituitary tumor-transforming gene (PTTG): a novel target for anti-tumor therapy.

BACKGROUND: The proto-oncogene pituitary tumor-transforming gene (PTTG) is described as abundantly over-expressed in a variety of neoplasms with impact on neovascularization and tumor invasiveness. Based on these findings, we raised the question as to whether PTTG is a target for an anti-tumor therapy. MATERIALS AND METHODS: To investigate the impact of PTTG depletion on the human cervical cancer cell line HELA-S3, we used antisense-oligodesoxynucleotides (antisense-ODNs) and subjected them to in vitro transfection experiments. The PTTG mRNA level was determined by RT-PCR (45 cycles) and PTTG protein levels were determined by Western blot experiments. The impact of PTTG depletion on cell growth was determined 24, 48 and 72 hours post transfection by the trypan blue exclusion method. RESULTS: We found an antisense-ODN effective in down-regulation of PTTG mRNA and protein level. Furthermore, transfection resulted in a significant growth inhibitory effect as well as an increased level of apoptotic figures. CONCLUSION: Our studies revealed an anti-tumor potential for this target in cancer therapy.

Cell Growth Processes↗

PubMedDate not supplied

The efficacy of MRI with ultrasmall superparamagnetic iron oxide particles (USPIO) in head and neck cancers.

BACKGROUND: The objective was to evaluate the diagnostic accuracy of ultrasmall superparamagnetic iron oxide (USPIO)-enhanced magnetic resonance imaging (MRI) compared to plain MRI in patients with a clinical N+ neck using histology as a gold standard. MATERIALS AND METHODS: Twenty-eight patients underwent unenhanced and USPIO-enhanced MRI using T1-weighted spin echo (SE) sequences and high resolution Turbo-Spin-Echo (TSE) T2-weighted sequences, as well as T2-weighted Gradient Echo (GE) sequences in axial and sagittal slice orientation. The signal intensity (SI) decrease was measured by a region of interest evaluation and visual analysis was performed. RESULTS: Histopathological evaluation of 363 lymph nodes revealed 34 as metastatic. USPIO MRI detected 28 metastases (sensitivity 82.3%) and 329 non-metastatic lymph nodes (specificity 100%). Regarding lymph node size, USPIO MRI was correct in all patients who underwent surgery. One lymph node with microinfiltration of tumor cells was detected by USPIO MRI. CONCLUSION: There were no side-effects during or after application of the contrast agent. This study confirms the efficacy of MRI with USPIO in patients with head and neck cancer. USPIO-enhanced MRI could have an important effect on surgery planning. Because of its high specificity, USPIO-enhanced MRI seems to be a diagnostic modality able to differentiate borderline-sized lymph nodes.

Adult↗

PubMedDate not supplied

Iressa (ZD 1839) inhibits phosphorylation of three different downstream signal transducers in head and neck cancer (SCCHN).

Proliferation of squamous cell carcinoma of the head and neck (SCCHN) depends on epidermal growth factor receptor (EGFR) expression. The EGFR activates different signal pathways leading to gene transcription in the nucleus due to cell cycle progression and proliferation of tumor cells. AKT, STAT3 and MAPK play central roles in these pathways. However, they are not only regulated by the EGFR. We therefore investigated whether a specific inhibitor of the EGFR tyrosine kinase (ZD 1839 or Iressa) is able to inhibit phosphorylation of these three signals at the same time. Western blot analysis of pretreated SCCHN cells revealed that ZD 1839 greatly reduces the amount of phosphorylated AKT, STAT3 as well as MAPK Surprisingly, this effect was not dose-dependent between the concentration range of 5.15 to 41.2 microM/ml. We conclude that Iressa has a high potency to inhibit nuclear gene transcription responsible for cell cycle progression. Furthermore, dose reduction of Iressa in the case of toxicity may not severely influence the response to treatment.

Antineoplastic Agents↗