Britta Kleist

Alterations in the tumor suppressor gene p16(INK4A) are associated with aggressive behavior of penile carcinomas.

Alterations in the p16/cyclinD1/Rb and ARF/Mdm2/p53 pathways are frequent events in the pathogenesis of squamous cell carcinomas. Different mechanisms of p16 regulation have been described for penile carcinomas so far. Therefore, expression of p16 and p53 was immunohistochemically detected with monoclonal antibodies in 52 primary invasive penile squamous cell carcinomas. The carcinomas were analyzed for allelic loss (LOH) in p16INK4A and p53, as well as for mutations in the p16INK4A and the p53 gene. In addition, we examined the promoter status of p16INK4A by methylation-specific PCR. The presence of human papilloma virus (HPV) 6/11, HPV 16 and HPV 18 DNA was analyzed by PCR. Data were compared to clinical data. Concerning p16, 26 (50%) tumors showed positive immunohistochemistry, 32 (62%) tumors showed allelic loss and 22 tumors (42%) showed promoter hypermethylation. All tumors with negative p16 immunohistochemistry showed LOH near the p16INK4A locus and/or hypermethylation of the p16INK4A promoter. HPV 16 DNA was detected in 17 tumors, ten of them with positive p16 immunostaining. The remaining seven tumors with negative p16 staining showed allelic loss and/or promoter hypermethylation. Evidence of lymph node metastasis was significantly associated with negative p16 immunohistochemistry as well as with combined LOH and promoter hypermethylation (p = 0.003 and p = 0.018, respectively). Allelic loss around p53 was found in 22 tumors (42%), and seven mutations of the p53 gene could be demonstrated in our tumors. No correlations could be found between any p53 alteration and clinical parameters.

Detection of new PTEN/MMAC1 mutations in head and neck squamous cell carcinomas with loss of chromosome 10

Alterations of the candidate tumor suppressor gene PTEN/MMAC1 and the cell cycle control gene p16((CDKN2/MTS-1/INK4a)) have been detected in many types of human cancer. Here, we wanted to study the role of PTEN/MMAC1 in head and neck squamous cell carcinomas (HNSCC) in correlation to mutation and methylation of p16 and to previous in situ hybridization results concerning loss of chromosomes 9 and 10. We screened for alterations of PTEN/MMAC1 and p16 in 52 HNSCC of different sites. Mutations of PTEN/MMAC1 were found in 23% of tumor samples (missense mutations in 7 carcinomas, 13%). A loss of chromosome 10 was detected in five carcinomas with missense PTEN/MMAC1 mutations (71%). The missense mutations of PTEN/MMAC1 occurred in exons 5 (five different mutations in the neighborhood of the protein tyrosine phosphatase domain), 6, 7, and 8. Only one of these mutations had been described before. In addition, in three laryngeal carcinomas (6%), missense mutations of p16 (in exon 2) were detected and 14% of carcinomas showed a methylation of p16. Our results focus on the essential but not solitary role of PTEN/MMAC1 in the tumorigenesis or progression of a subset of HNSCC.

Different risk factors in basaloid and common squamous head and neck cancer.

Objectives/Hypothesis: The prevalence of human papillomavirus (HPV), herpes simplex virus (HSV), cigarette smoking and alcohol abuse was compared between two histological subgroups of head and neck cancer.

Down-regulation of the metastasis suppressor protein KAI1/CD82 correlates with occurrence of metastasis, prognosis and presence of HPV DNA in human penile squamous cell carcinoma

In penile squamous cell carcinoma (PSCC), the outcome largely depends on early detection and resection of inguinal lymph node metastases. We investigated the role of metastasis suppressor protein kang ai 1 (KAI1)/cluster of differentiation 82 (CD82), which is known to be of prognostic significance for a wide variety of cancers. Moreover, we analysed the tumours for human papillomavirus (HPV) DNA and loss of heterozygosity at the 11p11.2 locus. Tissue samples of 30 primary PSCCs were investigated immunohistochemically using an anti-KAI1/CD82 polyclonal antibody. The expression was assessed according to the degree of KAI1/CD82-positive tumour cells as positive, decreased or negative. The presence of HPV6/11, HPV16 and HPV18 DNA was analysed by polymerase chain reaction. All patients with decreased or negative expression of KAI1/CD82 in primary lesions had lymph node metastases (p = 0.0002). Patients with positive KAI1/CD82 expression showed a significant better prognosis for survival compared to the other groups (p = 0.0042). Presence of HPV DNA was associated with decreased or negative KAI1/CD82 expression. Lacking or decreased expression of metastasis suppressor gene KAI1/CD82 appears to be a prognostic parameter for the occurrence of lymph node metastases in PSCC. Our study suggests an association of decreased KAI1/CD82 expression with tumour progression, development of metastases and disease-specific death.

Basaloid in contrast to nonbasaloid head and neck squamous cell carcinomas display aberrations especially in cell cycle control genes.

At present, the differences between head and neck basaloid squamous cell carcinoma (BSCC) and nonbasaloid squamous cell carcinoma (SCC) are mostly on the basis of histologic and immunohistologic findings.

Relationship between mitochondrial DNA instability, mitochondrial DNA large deletions, and nuclear microsatellite instability in head and neck squamous cell carcinomas.

Mitochondrial DNA (mtDNA) mutations in coding and noncoding regions have been reported in a variety of human cancers. Despite a greater number of studies, the relationship between such alterations and nuclear microsatellite instability (nMSI) of the tumor cells remains controversial. To contribute new data to this discussion, we investigated head and neck squamous cell carcinomas (HNSCC) for mutations and mitochondrial microsatellite instability (mtMSI) in 2 parts of the mitochondrial d-loop as well as mutations in 2 mitochondrial genes and for the &Dgr;4977 mtDNA deletion. These results were compared with data of an analysis for microsatellite instability at IGFIIR, hMSH3, hMSH6, and 5 dinucleotide repeats. We found mtMSI, low nMSI, and high nMSI in 42%, 36%, and 13% of HNSCC primary tumors, respectively. A de novo &Dgr;4977 mtDNA deletion could be demonstrated in 25% of HNSCCs. A correlation between mtMSI and nMSI or between a de novo occurrence of the &Dgr;4977 mtDNA deletion and nMSI could not be detected in our HNSCC samples (P values 0.527 and 0.078, respectively). Nevertheless, the high rate of mtMSI suggests an involvement of mtDNA alterations in the tumorigenesis of this head and neck cancer and supports the proposal that this aberration may be a new tumor marker.

Intranodal palisaded myofibroblastoma with overexpression of cyclin D1.

Intranodal palisaded myofibroblastoma (IPM) is a rare benign spindle-cell tumor of lymph nodes with myofibroblastic/smooth muscle differentiation. We present another case of IPM that confirms the myofibroblastic differentiation of the tumor cells and identifies the so-called amianthoid fibers as collagen deposits by immunohistochemical and ultrastructural techniques. Because IPM shares histomorphologic characteristics with an inflammatory myofibroblastic tumor that has been associated with a virus-induced alteration of cell cycle regulation, the diagnostic approach was extended in this case. We were able to demonstrate cyclin D1 overexpression but could detect neither amplification of the CCND1 gene nor allelic loss at chromosomes 9p22-21 and 13q (surrounding the genes p16 and Rb, respectively). Furthermore, no evidence of human herpesvirus-8 or Epstein-Barr virus infection could be found by polymerase chain reaction or immunostaining. Nevertheless, our results point to the cell cycle regulatory genes as a factor in the pathogenesis of IPM.

Screening of microsatellite markers in penile cancer reveals differences between metastatic and nonmetastatic carcinomas

Penile cancer, observed only rarely in the western world, represents a carcinoma that may be cured by resection of primary lesion and in case of lymph node metastasis by early lymph node dissection. This early inguinal lymphadenectomy bares a significant better survival even in cases of nonpalpable lymph nodes, but carries also a high risk of overtreatment, especially in lower tumor stages. Due to the low incidence, only few data are available on the molecular genetic background of this tumor, especially concerning tumor progression and metastasis. Therefore, we studied 62 microsatellite markers in 28 penile carcinomas searching for markers predicting progression or outcome. LOH in more than 25% of primary tumors was found on six different chromosomes, including 2q, 6p, 8q, 9p, 12q and 17p13. Statistically significant correlations could be established in D6S260 to clinical outcome and in markers from chromosomes 6, 9 and 12 to tumor stage and metastasis. These regions are worthy for further analysis concerning tumor suppressor genes and metastasis suppressor genes.

Loss of heterozygosity at 15q21.3 correlates with occurrence of metastases in head and neck cancer

Deletions on the long arm of chromosome 15 suggesting the presence of potential tumor suppressor genes have been found in several tumors including carcinomas of the colorectum, urinary bladder, breast, lung, and head and neck. Here, we analyzed allelic imbalance on chromosome 15q in head and neck carcinomas and corresponding lymph node metastases to define common regions of aberrations with potential involvement in development and progression of these tumors. We studied a panel of 40 polymorphic microsatellite markers, spanning 15q13–15q26, in 63 head and neck carcinomas and 38 lymph node metastases. Loss of heterozygosity (LOH) could be demonstrated in 34 primary tumors (54%) and 35 metastases (92%). Aberration mapping defined three minimum regions of aberrations: a region between the markers D15S106 and D15S1029 in 15q21.3 (estimated as 3.9 Mb; region 1) was affected in the majority of tumors, whereas two other regions between D15S144 and D15S1040 in 15q13.3–14 (estimated as 2.4 Mb; region 2) and between D15S130 and D15S985 in 15q26.2–26.3 (estimated as 4.7 Mb; region 3) were less often involved. Allelic loss in region 1 correlated with T stages (P=0.0029) and metastatic potential (P=0.0018). LOH in regions 2 and 3 occurred predominantly in metastases (P=0.0129 and P=0.0013, respectively). No correlation with grading, localization, or clinical outcome could be established for any of the affected regions. Our data hint at aberrations in 15q21.3 as a possible important characteristic for head and neck squamous cell carcinomas with risk of progression.

Differential expression of the subunits of the glucose-6-phosphatase system in the clear cell type of human renal cell carcinoma – no evidence for an overexpression of protein kinase B

The expression of two components of the glucose-6-phosphatase system, the catalytic subunit (G6PaseC) and the glucose-6-phosphate transporter, was analyzed in the clear cell type of human renal cell carcinoma. The expression of G6PaseC was decreased in tumours compared with non-tumourous tissue of the same patient. The expression of G6PaseT varied with no general trend between tumours and control tissue. The expression of protein kinase B (PKB) was unchanged in the tumours, suggesting that the down-regulation of G6PaseC in clear cells and the maintenance of the transformed phenotype are not predominantly caused by an overexpression of PKB.