Hyung Woo Kim

Development of Biologic Markers of Response and Assessment of Antiangiogenic Activity in a Clinical Trial of Human Recombinant Endostatin

PURPOSE Angiogenesis is a target for the treatment of cancer and other diseases, and its complex biology suggests that establishing the appropriate dose and schedule for antiangiogenic treatment will require extensive study. We present the initial results of a dose-finding clinical trial of recombinant human endostatin (rh-Endo) that examined potential surrogates for response to antiangiogenic therapy. PATIENTS AND METHODS Twenty-five patients were treated with escalating doses of rh-Endo. Positron emission tomography (PET) was used to assess tumor blood flow (with [15O]H2O) and metabolism (with [18F]fluorodeoxyglucose) before the start of therapy and then every 4 weeks. To directly assess the effects of rh-Endo on endothelial cells within the tumors, biopsy specimens of tumor tissue were obtained before therapy and again at 8 weeks and evaluated for endothelial cell and tumor cell apoptosis. RESULTS Tumor blood flow and metabolism as measured by PET scans generally decreased with increasing doses of rh-Endo; however, the effects were complex and in some analyses nonlinear. Tumor biopsy analysis revealed a significant increase in tumor cell apoptosis (P =.027) and endothelial cell apoptosis (P =.027) after 8 weeks of therapy. However, there was no statistically significant relationship between rh-Endo dose and induction of tumor cell or endothelial cell apoptosis. CONCLUSION These initial data suggest that rh-Endo has measurable effects on tumor blood flow and metabolism and induces endothelial and tumor cell apoptosis even in the absence of demonstrable anticancer effects. Further study and validation of these biomarkers in the context of antiangiogenic therapy will be required.

Differential expression profiling of head and neck squamous carcinoma: Significance in their phenotypic and biological classification

The genetic events associated with the development and progression of head and neck squamous carcinoma (HNSC) are largely unknown. We analysed 12 matched pairs of histologically normal squamous mucosa and tumor specimens from six conventional and six phenotypic variants HNSC to define the differentially expressed genes in these tumors. Parallel expression analysis of 8055 unique genes was performed, and the level of the hybridization signal for each gene was measured after normalization. Hierarchical cluster analysis of the expressed genes showed distinct inter- and intra-tumoral patterns in and between conventional squamous carcinoma and squamous carcinoma variants. We also identified 26 (0.32%) differentially expressed genes that were consistently different between matched pairs of normal and tumor specimens; a selected set of the overexpressed genes was validated using real-time quantitative RT–PCR. The majority of the genes were associated with differentiation and proliferation. Our study defines a set of genes that could form the basis for the construction of limited HNSC targeted expression array and indepth studies and further highlights gene profile differences that may be useful in pathobiologic classification of HNSC.

Gene Expression Screening of Salivary Gland Neoplasms: Molecular Markers of Potential Histogenetic and Clinical Significance

Salivary gland neoplasms comprise phenotypically and biologically diverse lesions of uncertain histogenesis. The molecular events associated with their development and clinicopathological heterogeneity remain unknown. To reveal these events, we performed microarray expression analysis using a nylon-filter membrane platform on 18 primary lesions representing the most common benign and malignant types. Our study identified a small set of genes that are differentially altered between normal salivary gland tissues and benign and malignant tumors. Of the 5000 genes arrayed, 136 genes were differentially expressed by normal tissue, benign tumors, and various malignant neoplasms. Hierarchical clustering analysis differentiated between adenoid cystic carcinomas (ACCs) and other malignant subtypes. Non-ACC specimens manifested overlapping patterns of gene expression within and between tumors. Most of the differentially expressed genes share functional similarities with members of the adhesion, proliferation, and signal transduction pathways. Our study identified: 1) a set of genes that differentiate normal tissue from tumor specimens, 2) genes that differentiate pleomorphic adenoma and ACCs from other malignant salivary gland neoplasms, and 3) different patterns of expression between ACCs arising from major and minor salivary gland sites. The differentially expressed genes provide new information on potential genetic events of biological significance in future studies of salivary gland tumorigenesis.

Primary hyperparathyroidism and osteosarcoma: examination of a large cohort identifies three cases of fibroblastic osteosarcoma.

To study a possible relationship between hyperparathyroidism and osteosarcoma, we reviewed 1234 osteosarcoma patients. In this cohort, only three patients had a diagnosis of both hyperparathyroidism and fibroblastic osteosarcoma. These results indicate that hyperparathyroidism is not more prevalent in patients with osteosarcoma than in the general population. However, the presence of hyperparathyroidism may modify the histologic and cytologic features of osteosarcoma.

Cooperation of Ha‐ras and Bcl‐2 during multistep skin carcinogenesis

Nonmelanoma skin cancer (NMSC) is the most frequently diagnosed cancer in the United States. Deregulation of bcl‐2 and ras family members is commonly observed in NMSC. It has been previously demonstrated that simultaneous bcl‐2 and Ha‐ras gene expression in keratinocytes results in disordered differentiation and resistance to cell death induced by ultraviolet (UV) radiation. It was, therefore, interest to assess the extent of cooperation between bcl‐2 and Ha‐ras during multistep skin carcinogenesis. The keratin 1 promoter was used to generate HK1.ras and HK1.bcl‐2 transgenic mice, which were subsequently crossed to generate HK1.ras/bcl‐2 double transgenic mice. The apoptotic index (AI) following UV‐irradiation was significantly lower in HK1.bcl‐2 and HKI.ras/bcl‐2 epidermis compared to control littermates. Interestingly, the AI of HK1.ras/bcl‐2 mice was significantly lower than even HK1.bcl‐2 mice following UV‐irradiation. To investigate the interaction of these oncogenes in skin tumorigenesis, a two‐stage chemical carcinogenesis protocol was used to induce tumors. The individual contributions of Ha‐ras and bcl‐2 to papilloma latency, incidence, and growth rate in HK1.ras/bcl‐2 double transgenic mice was marginally additive. Papillomas arising in HK1.ras transgenic mice exhibited the highest rate of apoptosis whereas papillomas arising in the HK1.ras/bcl‐2 double transgenic mice exhibited rates of apoptosis that were significantly lower than papillomas arising in either control littermate or HK1.ras mice. Constitutive expression of either Ha‐ras or bcl‐2 exhibited similar rates of malignant tumor progression and they were not significantly different than control littermates. Importantly, when these two oncoproteins were coexpressed, a significant, and synergistic, increase in malignant transformation was observed.