Our research group focuses on the identification of genomic and phenotypic alterations involved in the pathogenesis of several epithelial and neuro-endocrine derived tumors in order to assess their relevance to predict their biological behavior and to improve the clinical management of cancer patients. In the past decade, collaboration of our research group with several departments in the academic hospital (azM), including Otorhinolaryngology and Head and Neck Surgery, Neurology, Internal Medicine and Pathology, and with other (inter)national institutes has resulted in a number of studies and PhD theses concerning genotypic and phenotypic aberrations identified during the progression of (pre)malignant lesions, such as bladder, brain and unknown primary cancer. In addition, the group is recognized for its expertise in the development and implementation of sensitive in situ hybridisation assays for genomic analysis of tumors.
Human papillomavirus and carcinogenesis
Our studies on uterine cervical and head and neck (pre)malignancies have shown that fluorescence in situ hybridization (FISH) can be reliably applied to assess HPV integration (fig 1A) as a highly sensitive marker for the transition of precursor lesion to invasive carcinoma. These data suggest that mostly singular integration events occur, which is in agreement with PCR-based assays. HPV integration results in disruption of the E1/E2 open-reading frames of the HPV genome, leading to increased expression of E6 and E7 mRNA and proteins. This is in agreement with our observation that individual integration signals harbour high levels of mRNAs. As a consequence p53 and pRb are downregulated favouring a growth advantage and neoplastic transformation. Expression of E6 also has been found to deregulate the telomerase pathway resulting in an upregulation of the telomerase activity. In a recently started PhD project, we have focused on the gene coding for the RNA component of telomerase (TERC) at 3q26 and showed that genomic integration of oncogenic HPV and gain of the human telomerase gene TERC (fig 1B) appear to be important associated genetic events in the progression of uterine cervical dysplasia to invasive cancer. Furthermore we were able to proof that integration of HPV and gain of TERC can occur in DNA diploid cells, suggesting that these events are early during cervical carcinogenesis. We obtained an additional grant (LIOF/PathoFinder) aimed to support the development of a sensitive multiplex PCR assay for HPV typing and chromosomal instability. With this assay we will be able to determine in a single assay the HPV genotype, viral load, physical status of the virus and genomic instability.
In oropharyngeal cancers we also established HPV integration in 40% of cases. In these tumors 3q gains has also been detected. Studies are carried out to unravel the molecular mechanisms underlying HPV driven tumorigenesis and to assess new prognostic markers.
Carcinogenesis of neuro-endocrine tumors
The molecular pathogenesis of neuro-endocrine tumors, including endocrine pancreatic tumors (EPTs), bronchial carcinoids, pheochromocytomas and adrenocortical tumors, is not well understood, and the clinical behavior of these tumors is difficult to predict using current morphological criteria.
Moreover, a substantial proportion of tumors is unresectable and responds unpredictable to palliative therapy. Thus, a better understanding of the molecular
processes underlying the tumorigenesis of neuro-endocrine tumors is required to improve diagnosis, prognosis and therapy. Continuation of a PhD study on human sporadic insulinomas revealed, that a high number of confined chromosomal alterations per tumor (defined as chromosomal instability) as well as loss of telomeric ends were strongly associated with metastatic disease. P53 and cytokeratin 19 (CK19) status proved to be of little value for this purpose, because only rare, individual cases showed a TP53 mutation (together with p53 overexpression) or detectable amounts of CK19. In addition, we showed by arrayCGH that gain of chromosome 9q and loss of 22q13.1-q13.31 are early genetic events in sporadic insulinomas, and that loss of 11q and 22q13.31-q13.32 occur later in the tumor development and are associated with loss of telomeric ends. On basis of these data we have proposed a genetic progression model for these tumors (see figure). Two project applications have been submitted to identify candidate genes on the aberrant chromosomal loci and to develop a multi-target test for discrimination of benign and malignant tumors on basis of chromosomal instability. In (inter)national collaborations, furthermore, arrayCGH has been used to identify chromosomal breakpoints on 1p, the most frequently involved genomic alteration in pheochromocytomas, and beta-interferon has been found a highly potent inhibitor of cell growth in neuro-endocrine tumors, including pancreatic carcinoids and adrenocortical carcinomas.
Selected publications
Jonkers YMH, Claessen SMH, Feuth T, Geurts van Kessel A, Ramaekers FCS, Veltman JA, Speel EJM.
Novel candidate tumor suppressor gene loci on chromosomes 11q23-24 and 22q13 involved in human insulinoma tumorigenesis.
J Pathol 210, 450-458, 2006 (IF: 6.213).
Hopman AHN, Theelen W, Hommelberg P, Kamps MA, Herrington CS, Morrison LE, Speel EJM, Smedts F, Ramaekers FCS.
Genomic integration of oncogenic HPV and gain of the Human Telomerase Gene TERC at 3q26 are strongly associated events in the progression of uterine cervical dysplasia to invasive cancer.
J Pathol 210, 412-419, 2006 (IF: 6.213).
Awards
- Speel EJM: Best oral communication, 20th European Congress of Pathology (received in Paris, France, September 6, 2005; Euro 1,500).
- Y. Jonkers: Best abstract, 3rd European NeuroEndocrine Tumor Society Congress (received in Prague, Chech Republic, March 24, 2006; Euro 1,500).
- Y. Jonkers: Rene Vogels Stipendium (received in Amsterdam, January 17, 2006; Euro 1,700).
Major Funding
Association for Internation Cancer Research:
Identification of genes involved in endocrine pancreatic tumor development and progression (Euro 185,000; PhD position)
Molecular Life Sciences tUL:
Impact of virus integration and chromosomal instability on the development and progression of Human Papillomavirus-related tumors (Euro 200,000; PhD position)
Research group
Dr. Anton H.N. Hopman, project leader
Dr. Ernst-Jan M. Speel, propject leader
Prof. Dr. Frans C.S. Ramaekers
Prof. Dr. Hans J. Manni
Prof. Dr. Bernd. Kremer
Prof. Dr. Philippe O. van Trappen
Prof. Dr. Adriaan de Bru?ne
Dr. Fredrik J. Bot
Dr. Els V. Meulemans
Dr. Frank Smedts
Dr. Manon van Engeland
Dr. Robert-Jan van Suijlen
Dr. Arnold Kruse
PhD students
Drs. Harriet C. Hafkamp
Drs. Yvonne M.H. Jonkers
Drs. V. Ewa Bergshoeff
Drs. Wendy Theelen
Boris Klingenberg
Drs. Jos Straatmans
Technicians
Annick Haesevoets
Sandra M.H. Claessen
Students
Yvo Kusters
Jeroen Mooren
Sophie Litjens
Jenneke Smeenk
Elly Jonker