Christoph Matthias

Clinical Predictors for Germline Mutations in Head and Neck Paraganglioma Patients: Cost Reduction Strategy in Genetic Diagnostic Process as Fall-Out

Multiple genes and their variants that lend susceptibility to many diseases will play a major role in clinical routine. Genetics-based cost reduction strategies in diagnostic processes are important in the setting of multiple susceptibility genes for a single disease. Head and neck paraganglioma (HNP) is caused by germline mutations of at least three succinate dehydrogenase subunit genes (SDHx). Mutation analysis for all 3 costs approximately US

Heterogeneous Nuclear Ribonucleoprotein H Blocks MST2-Mediated Apoptosis in Cancer Cells by Regulating a-raf Transcription

2,700 per patient. Genetic classification is essential for downstream management of the patient and preemptive management of family members. Utilizing HNP as a model, we wanted to determine predictors to prioritize the most heritable clinical presentations and which gene to begin testing in HNP presentations, to reduce costs of genetic screening. Patients were tested for SDHB, SDHC, and SDHD intragenic mutations and large deletions. Clinical parameters were analyzed as potential predictors for finding germline mutations. Cost reduction was calculated between prioritized gene testing compared with that for all genes. Of 598 patients, 30.6% had SDHx germline mutations: 34.4% in SDHB, 14.2% SDHC, and 51.4% SDHD. Predictors for an SDHx mutation are family history [odds ratio (OR), 37.9], previous pheochromocytoma (OR, 10.9), multiple HNP (OR, 10.6), age <or=40 years (OR, 4.0), and male gender (OR, 3.5). By screening only preselected cases and a stepwise approach, 60% cost reduction can be achieved, with 91.8% sensitivity and 94.5% negative predictive value. Our data give evidence that clinical parameters can predict for mutation and help prioritize gene testing to reduce costs in HNP. Such strategy is cost-saving in the practice of genetics-based personalized health care.

Molecular characterization of the tumor-associated antigen AAA-TOB3.

A-Raf belongs to the family of oncogenic Raf kinases that are involved in mitogenic signaling by activating the mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase (MEK)-ERK pathway. Low kinase activity of A-Raf toward MEK suggested that A-Raf might have alternative functions. Here, we show that A-Raf prevents cancer cell apoptosis contingent on the expression of the heterogeneous nuclear ribonucleoprotein H (hnRNP H) splice factor, which is required for the correct transcription and expression of a-raf. Apoptosis was prevented by A-Raf through sequestration and inactivation of the proapoptotic MST2 kinase. Small interfering RNA-mediated knockdown of hnRNP H or A-Raf resulted in MST2-dependent apoptosis. In contrast, enforced expression of either hnRNP H or A-Raf partially counteracted apoptosis induced by etoposide. In vivo expression studies of colon specimens corroborated the overexpression of hnRNP H in malignant tissues and its correlation with A-Raf levels. Our findings define a novel mechanism that is usurped in tumor cells to escape naturally imposed apoptotic signals.

Epigallocatechin-3-gallate reduces DNA damage induced by benzo(a)pyrene diol epoxide and cigarette smoke condensate in human mucosa tissue cultures.

Abstract.In search for new valuable tumor-associated antigens using the AMIDA technique, we identified the KIAA 1273-AAA-TOB3 protein. KIAA 1273 and AAA-TOB3 were considered synonyms for the atad3B gene product. We show that the atad3b gene encodes two distinct proteins, both overexpressed in head and neck carcinomas and required for correct cell division. Both products differ within the N terminus, are generated upon distinct transcription initiation sites, and have been termed AAA-TOB3s and AAA-TOB3l. Both isoforms are early targets of c-myc and are located in mitochondria. A previous report suggested pro-apoptotic properties of the murine homolog of AAA-TOB3l. Here, we did not observe any pro-apoptotic effects in human cell lines, overexpressing h-AAA-TOB3s or h-AAA-TOB3l. By contrast, the specific knock-down of both mRNAs resulted in polynuclear cells and decreased proliferation, along with dysfunctional cell division followed by increased apoptosis. Thus, the present data suggest a role for AAA-TOB3s/l in tumor progression.

Immunolocalization of antimicrobial and cytoskeletal components in the serous glands of human sinonasal mucosa.

Although epidemiological studies indicate cancer preventive effects of diets rich in fruit and vegetables, large clinical intervention studies conducted to evaluate dietary supplementation with micronutrients, mostly vitamins, showed disappointing results in large parts. In contrast, there is encouraging epidemiologic data indicating great chemopreventive potential of a large group of phytochemicals, namely polyphenols. This study shows the DNA protective effect epigallocatechin-3-gallate, a tea catechin, and one of the best-studied substances within this group, on carcinogen-induced DNA fragmentation in upper aerodigestive tract cells. Cell cultures from fresh oropharyngeal mucosa biopsies were preincubated with epigallocatechin-3-gallate in different concentrations before DNA damage was introduced with the metabolically activated carcinogen benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide or cigarette smoke condensate. Effects on resulting DNA fragmentation were measured using the alkaline single-cell microgel electrophoresis (comet assay). Epigallocatechin-3-gallate significantly reduced benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide-induced DNA damage by up to 51% (P<0.001). Fragmentation induced by cigarette smoke condensate could be lowered by 47% (P<0.001). Data suggest a cancer preventive potential of epigallocatechin-3-gallate as demonstrated on a subcellular level. An additional mechanism of tea catechin action is revealed by using a primary mucosa culture model.

Head and Neck Paragangliomas

Secretory cells in the seromucous glands of paranasal sinuses secrete antibacterial proteins for innate immune mucosal integrity. We studied the localization of antimicrobial and cytoskeletal components of the human seromucous glands and respiratory epithelium of the maxillary sinus and the ethmoidal cells by immunohistochemical methods. The presence of a variety of defense proteins such as lysozyme, lactoferrin, cathelicidin, and defensin-1, -2, -3 point to a crucial role in the immune defense for the respiratory tract. Cytoskeletal proteins such as actin, myosin 2, cytokeratin 7 and 19, α- and β-tubulin, investigated for the first time in glands of paranasal sinuses, showed a stronger expression at the apical and lateral cell membrane. The localization of the cytoskeletal proteins might point to their participation in exocrine secretory processes and stabilizing effects.

Genotoxic effects of metals on human salivary gland tissue and lymphocytes as detected by the Comet assay

Head and neck paragangliomas are highly vascularized neuroendocrine tumors derived from the extra-adrenal paraganglia of the autonomic nervous system. These tumors may occur either sporadically or in the context of a hereditary familial tumor syndrome, and multifocal presentations are observed, particularly in hereditary cases. Hereditary paragangliomas are mostly caused by mutations in the succinate dehydrogenase complex genes. Early imaging, with ultrasonography of the neck and magnetic resonance imaging (MRI) of the skull base, is essential for localizing and assessing the extent of the tumor, as well as for precise planning of the treatment approach. Views regarding the treatment of choice are generally moving away from radical resection toward surgical tumor reduction in order to preserve function and reduce morbidity. Radiotherapy modalities are alternative primary treatment options, depending on the individual situation (e.g., in relation to age, comorbidity, multifocal lesions, and risk of injury to the cranial nerves). Observation is an option in selected patients. The potential morbidity of surgical treatment must be weighed against the expectable quality of life, and comprehensive consultation with the patient about the possible treatment modalities is mandatory. Treatment decision-making should involve a multidisciplinary team of experts in the fields of nuclear medicine, genetics, pathology, radiology, radio-oncology, and surgery.

CK8 correlates with malignancy in leukoplakia and carcinomas of the head and neck.

The etiology of salivary gland malignancies still remains unclear. Metal compounds are of special interest since they show ubiquitous presence in the environment, are present in many working places, and are accepted (co-)carcinogens in some other malignancies. Metals enter the body as xenobiotics by inhalation or ingestion. This study investigated the genotoxic potential of sodium dichromate (Na2Cr2O7), nickel sulfate (NiSO4), cadmium sulfate (CdSO4) and zinc chloride (ZnCl2) on human salivary gland cells and lymphocytes. Macroscopically healthy tissue of salivary glands was harvested from 46 patients during surgery and isolated to single cells by enzymatic digestion. The cells were incubated with Na2Cr2O7, NiSO4, CdSO4 or ZnCl2. Na2Cr2O7 was also incubated in combination with the other metal compounds listed. Carcinogenic and co-carcinogenic effects of cadmium were tested by incubation with Na2Cr2O7 and consecutive repair intervals. DNA damage and repair were evaluated by the Comet assay, determining DNA-strand breaks. The extent of damage was quantified using a digital analysis system. Na2Cr2O7 produced significantly enhanced DNA-strand breaks in human salivary gland tissue and lymphocytes. All other metal compounds exerted no damaging effect on both cell types. Co-incubation of Na2Cr2O7 with the other metals revealed a significant additive effect only for CdSO4. Specific analysis of the influence of cadmium showed a reduction of DNA-repair after Na2Cr2O7-induced strand breaks in salivary gland cells. This study provides evidence that exposure to distinct metals may significantly contribute to malignant salivary gland tumors. In consequence, further studies as epidemiological and toxicological data are warranted to determine the role of distinct metals as potential (co-) carcinogens.