DNA Topoisomerase II-alpha as a marker of cell proliferation in endocrine and other neoplasms

The significance of Epstein Barr virus (EBV) & DNA topoisomerase II alpha (DNA-Topo II alpha) immunoreactivity in normal oral mucosa, oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC)

Background

Head and neck cancer including oral cancer is considered to develop by accumulated genetic alterations and the major pathway is cancerization from lesions such as intraepithelial dysplasia in oral leukoplakia and erythroplakia. The relationship of proliferation markers with the grading of dysplasia is uncertain. The involvement of EBV in oral carcinogenesis is not fully understood.

Aim

The present study was designed to investigate the role of EBV and DNA Topoisomerase II∝ (DNA-Topo II∝) during oral carcinogenesis and to examine the prognostic significance of these protein expressions in OSCCs.

Methods

Using specific antibodies for EBV and DNA-Topo II∝, we examined protein expressions in archival lesion tissues from 16 patients with oral epithelial dysplasia, 22 oral squamous cell carcinoma and 20 normal oral mucosa by immunohistochemistry. Clinical information was obtained through the computerized retrospective database from the tumor registry.

Results

DNA-Topo II∝ was expressed in all examined specimens. Analysis of Variance ANOVA revealed highly significant difference (P < 0.01) in young aged labial tissues and significant (P ≤ 0.05) in gingival and not significant (P > 0.05) in inferior surface of tongue and in hard palatal tissues. Significant differences were observed between OEDs and NSE (P < 0.001) and SCCs and controls (P < 0.001), also, significant differences could be observed between SCCs and OEDs. DNA-Topo II∝ expression was significantly higher in tumors of low differentiation versus tumors of moderate and high differentiation (P < 0.001), DNA-Topo II∝ expression was correlated with age, tumor size, tumor stage, node metastasis and tumor differentiation, but not with gender and tumor site. None of normal squamous epithelium (NSE) expressed EBV. Heterogenous reactivity for EBV was observed through the series of dysplasia and squamous cell carcinoma. Its expression increased progressively with lymph node metastasis and low tumor differentiation, but no significant association could be observed with other clinicopathological parameters. EBV protein expression was increased with elevated Topo II-∝ LI in OEDs and OSCCs. A tendency to positive correlation between EBV and Topo II∝ expression was observed in OEDs but not in OSCCs.

Conclusion

EBV and DNA Topo II-αLI expression are possible indicators in oral carcinogenesis and may be valuable diagnostic and prognostic indices in oral carcinoma.

Prognostic significance of cyclooxygenase-2 and DNA topoisomerase IIalpha expression in oral carcinoma

BACKGROUND

Despite recent advances in the diagnosis and treatment of oral carcinoma, outcomes remain disappointing. The identification of new prognostic factors is necessary to improve survival. To determine the prognostic significance of cyclooxygenase (COX)-2 and DNA topoisomerase (DNA-Topo) IIalpha expression in patients with oral carcinoma, we immunohistochemically examined these enzymes and studied their relation to overall 5-year survival.

METHODS

Surgical specimens were obtained from 160 patients with oral carcinoma, 80 with and 80 without regional lymph node metastasis. The specimens were immunostained for COX-2 and DNA-Topo IIalpha as an index of cell proliferative activity. COX-2 immunoreactivity and clinicopathological data were analyzed, and 5-year survival was calculated by the Kaplan-Meier method.

RESULTS

COX-2 expression in primary lesions was higher in cases with lymph node metastasis than in those without lymph node metastasis. An increase in tumor size was associated with increased COX-2 expression. In most cases with lymph node metastasis, COX-2 expression was higher in metastatic lesions than in primary lesions. As COX-2 expression increased, the DNA-Topo IIalpha labeling index significantly increased and the overall 5-year survival rate decreased.

CONCLUSION

Expression of COX-2 and DNA-Topo IIalpha were related to lymph node metastasis, cell proliferative activity, and overall 5-year survival rate in oral carcinoma. These enzymes may therefore be valuable diagnostic and prognostic indices in oral carcinoma.

Human DNA topoisomerase I: An anticancer drug target present in human sarcomas

New anticancer drugs targeting DNA topoisomerase I (topo I) are showing activity against human sarcomas. Laboratory studies have indicated that cells responsive to topo I-targeted drugs have elevated levels of topo I, require active DNA replication, and may require a functional apoptotic pathway. In this study, we evaluated these potential markers of topo I-targeted drug sensitivity in 55 cases of human sarcoma (42 high grade, 4 intermediate grade, and 9 low grade). By immunohistochemical staining, we observed elevated topo I expression in 20 of 55 neoplasms (36%). Immunohistochemical staining for the proliferation marker DNA topoisomerase II-alpha (topo II-alpha), showed that 15 of 55 neoplasms (27%) had topo II-alpha indices >50, indicating a large number of actively cycling tumor cells. Abnormal p53 expression was observed in 19 of the 55 cases (35%). None of the cases were interpreted as positive for ALK-1. To complement our immunohistochemical staining of topo I, we isolated functionally active topo I from extracts of a human sarcoma. These isolates demonstrated that sarcoma topo I is sensitive to topo I-targeted anticancer drugs. Of the 55 cases of human sarcoma, 7 (13%) had high levels of topo I, a large number of cycling tumor cells, and normal p53 expression. These are the molecular parameters that might suggest responsiveness to drugs targeting topo I.

Defining a molecularly normal colon

As techniques evolve that allow molecular characterization of disease processes such as cancer, definition of "normal" at a molecular level becomes increasingly important. Increasingly large numbers of mutations are found at the genomic level, but whether all of those mutations contribute to the malignant state of a carcinoma cell is not clear. Without knowledge of what constitutes normality on the proteomic level in an organ or cell, we cannot determine what genomic changes are physiologically important. Traditionally, colon cancer is identified and classified by histological criteria. Margins of the colon are defined as "grossly uninvolved" when the histology is indistinguishable from that of normal (free from disease) colon. By using molecular pathology techniques and working backward from colon adenocarcinoma to hypoplastic polyps to presumably normal mucosa, we defined some of those protein differences. Our results may provide a molecular basis for identifying tumor formation and progression in situ.(J Histochem Cytochem 49:667-668, 2001)