P.J. Slootweg

An expression profile for diagnosis of lymph node metastases from primary head and neck squamous cell carcinomas

Metastasis is the process by which cancers spread to distinct sites in the body. It is the principal cause of death in individuals suffering from cancer. For some types of cancer, early detection of metastasis at lymph nodes close to the site of the primary tumor is pivotal for appropriate treatment. Because it can be difficult to detect lymph node metastases reliably, many individuals currently receive inappropriate treatment. We show here that DNA microarray gene-expression profiling can detect lymph node metastases for primary head and neck squamous cell carcinomas that arise in the oral cavity and oropharynx. The predictor, established with an 82-tumor training set, outperforms current clinical diagnosis when independently validated. The 102 predictor genes offer unique insights into the processes underlying metastasis. The results show that the metastatic state can be deciphered from the primary tumor gene-expression pattern and that treatment can be substantially improved.

Survival analysis of head and neck squamous cell carcinoma: Influence of smoking and drinking

Head and neck squamous cell carcinomas (HNSCCs) are associated with tobacco and alcohol; however, the prognostic relevance of these substances is unclear.

Dissection of a metastatic gene expression signature into distinct components

BackgroundMetastasis, the process whereby cancer cells spread, is in part caused by an incompletely understood interplay between cancer cells and the surrounding stroma. Gene expression studies typically analyze samples containing tumor cells and stroma. Samples with less than 50% tumor cells are generally excluded, thereby reducing the number of patients that can benefit from clinically relevant signatures.ResultsFor a head-neck squamous cell carcinoma (HNSCC) primary tumor expression signature that predicts the presence of lymph node metastasis, we first show that reduced proportions of tumor cells results in decreased predictive accuracy. To determine the influence of stroma on the predictive signature and to investigate the interaction between tumor cells and the surrounding microenvironment, we used laser capture microdissection to divide the metastatic signature into six distinct components based on tumor versus stroma expression and on association with the metastatic phenotype. A strikingly skewed distribution of metastasis associated genes is revealed.ConclusionDissection of predictive signatures into different components has implications for design of expression signatures and for our understanding of the metastatic process. Compared to primary tumors that have not formed metastases, primary HNSCC tumors that have metastasized are characterized by predominant down-regulation of tumor cell specific genes and exclusive up-regulation of stromal cell specific genes. The skewed distribution agrees with poor signature performance on samples that contain less than 50% tumor cells. Methods for reducing tumor composition bias that lead to greater predictive accuracy and an increase in the types of samples that can be included are presented.

Immunohistochemical demonstration of bcl-2 protein in human tooth germs

This study sought to detect patterns of bcl-2 protein expression that could provide more insight into the cellular dynamics of tooth development. As bcl-2 serves to prevent cell death, its occurrence in odontogenic tissues might be helpful in identifying cell populations from which odontogenic tumours may arise. The bcl-2 protein was found only in the epithelial part of the tooth germ and was present in all parts of the enamel organ except the ameloblast. This suggests that bcl-2 protein plays a part in maintaining the viability of the enamel organ. The presence of bcl-2 in the fully matured tooth germ and adjacent dental lamina might indicate that epithelial odontogenic tumours may originate from various parts of the enamel organ.

T Cell Apoptosis in Human Heart Allografts : Association with Lack of Co-Stimulation?

It is unclear whether the intracardial immune reactivity after heart transplantation influences the peripheral immunological status (activation or nonresponsiveness) of the patient. Co-stimulation and activation-induced cell death (AICD) or apoptosis play an important role in determining the balance between lymphocyte reactivity and nonreactivity. Therefore, we studied the expression of co-stimulatory molecules and the process of apoptosis in biopsies of human heart allografts, using immunohistochemistry. Although a normal expression of co-stimulatory molecules on antigen-presenting cells was observed, the expression of their counter-structures on T cells was absent. This may be due to chronic T cell activation, which can lead to the induction of apoptosis via the Fas/Fas ligand pathway. In the infiltrates, a considerable percentage of the lymphocytes, but not the macrophages, were apoptotic. Apoptosis was confirmed by DNA fragmentation analysis. Increased numbers of Bax-expressing versus decreased numbers of Bcl2-expressing lymphocytes in comparison with normal lymphoid tissue confirmed a imbalance in favor of apoptosis. Apoptosis was biased towards CD4+ T cells (65.7% versus 26.6% in CD8+ T cells). Fas was expressed on most of the infiltrating cells. Fas ligand expression was also observed, not only on most of the T cells but also on all macrophages. Because macrophages were often detected in close contact with T cells, they may play a role in T cell regulation via the Fas/Fas ligand pathway. This study indicates that, during rejection, not only is tissue damage induced by infiltrating T cells, but also the infiltrating lymphocytes themselves are actively down-regulated (eg, AICD) by one another and by macrophages in the infiltrate. This regulatory process may affect the immunological status of the patient after heart transplantation.

Head and neck squamous cell carcinoma in non-smoking and non-drinking patients with multiple tumors: etiologic significance of p53 and Ki-67 in non-tumorous epithelium.

BACKGROUND Non-smoking and non-drinking patients with head and neck squamous cell carcinoma have different clinical characteristics than their smoking and drinking counterparts. They are predominantly older female patients with oral cavity tumors, however, both groups show the same percentage of second primary tumors. Expression of tumor suppressor gene p53 and proliferation marker Ki-67 in mucosal epithelial cells was analyzed to study whether biomarker expression is associated with a history of smoking and drinking and with single and multiple tumors. METHODS Non-smoking and non-drinking patients with multiple (n = 18) and single tumors (n = 15), smoking and drinking patients with multiple (n = 15) and single tumors (n = 14) were selected. For all groups, p53 and Ki-67 expression patterns in non-tumorous (tumor-adjacent) mucosa including positivity of dispersed single cells and clusters for p53 and for suprabasal expression of Ki-67 were immunohistochemically analyzed and compared. RESULTS p53 expression was significantly higher in users of tobacco and alcohol than in non-users. Ki-67 expression was not affected by tobacco and alcohol usage. Both Ki-67 and p53 were similarly expressed in the groups with single and multiple tumors and hence not significantly related to the number of tumors. CONCLUSIONS Non-smoking and non-drinking patients with squamous cell carcinoma have the same risk for developing multiple tumors as their smoking and drinking counterparts. As this occurs without an increased expression of p53 or Ki-67, the significance of these proteins as biomarkers indicating pre-malignant mucosal alterations is doubtful. Further research is needed to clarify this predisposition for developing multiple head and neck cancer.

Lymphocytes at tumor margins in patients with head and neck cancer. Relationship with tumor size, human lymphocyte antigen molecules, and metastasis

A series of 76 patients with head and neck squamous cell carcinoma (HNSCC) was analyzed for the significance of a peritumoral lymphocytic infiltrate (PLI). The composition of PLI was immunohistochemically investigated in frozen material and correlated with other putative prognostically significant variables. PLI was shown to be correlated with the invasion pattern but not with any of the other investigated variables such as tumor size, thickness, and metastasis. However, individual components of PLI were statistically significant: human lymphocyte antigen (HLA)-class II-positive cells correlated with occurrence of metastasis, and CD22-positive cells correlated with tumor size. We conclude that studies on the significance of PLI in HNSCC patients should concentrate on analysis of its individual components.