Analysis of c-erbB-2 amplification in salivary gland tumours by differential polymerase chain reaction

Advanced diagnostic methods in oral and maxillofacial pathology. Part I: molecular methods

The practice of pathology is currently undergoing significant change, in large part due to advances in the analysis of DNA, RNA, and proteins in tissues. These advances have permitted improved biologic insights into many developmental, inflammatory, metabolic, infectious, and neoplastic diseases. Moreover, molecular analysis has also led to improvements in accuracy of disease diagnosis and classification. It is likely that, in the future, these methods will increasingly enter into the day-to-day diagnosis and management of patients. The pathologist will continue to play a fundamental role in diagnosis and will likely be in a pivotal position to guide the implementation and interpretation of these tests as they move from the research laboratory into diagnostic pathology. The purpose of this 2-part series is to provide an overview of the principles and applications of current molecular biologic and immunologic tests. Part I will discuss the biologic fundamentals of DNA, RNA, and proteins and the methods that are currently available or likely to become available to the pathologist in the next several years for their isolation and analysis in tissue biopsies.

Prognostic significance of biomarkers (c-erbB-2, p53, proliferating cell nuclear antigen, and DNA content) in salivary duct carcinoma

Salivary duct carcinoma (SDC), a rare neoplasm of the major salivary glands, is a high-grade carcinoma with a predilection for elderly men. The authors investigated the prognostic role of p53, c-erbB2, proliferating cell nuclear antigen (PCNA), and DNA flow cytometry in a pathobiological evaluation of a cohort of 30 patients with these neoplasms. The patient group comprised 24 men and 6 women, with ages ranging from 22 to 87 years (mean = 61 years). Twenty-eight tumors were located in the parotid gland and two in the submandibular gland. Tumor size ranged from 1.0 to 8.0 cm (mean = 3.48 cm). Regional metastases were found in 73.3% (22 patients), systemic metastases in 43.3% (13 patients), and recurrences in 8 (26.6%) patients. DNA aneuploidy was found in 18 tumors (58.0%) and DNA diploidy in 12 (42%), with proliferative fractions ranging from 8.60% to 15.5 (mean = 10.6%). p53 protein nuclear immunostaining was positive in 56.6% and c-erbB2 overexpression was observed in 63% of the tumors. PCNA positivity ranged from 16.5% to 91.0%, with a mean of 49.5%. p53 immunopositivity, DNA aneuploidy, high growth, and proliferative fractions by PCNA and flow cytometry did not correlate with patient outcome. These results indicate that tumor size (P = .05), distant metastasis (P = .006), and C-erbB2 amplification (P = .04) are independent prognostic parameters in patients with salivary duct carcinoma.

Demonstration of c-erbB-2 oncogene overexpression in salivary gland neoplasms by in situ hybridization

The level of c-erbB-2 cellular mRNA in 18 salivary gland tumours and in 7 normal salivary glands was determined by in situ hybridization using [35S] labelled RNA probes. Computer assisted quantitation of the autoradiographic signal indicated a significantly higher c-erbB-2 expression in the tumour group (22.64 grains per cell +/- 3.79; 95% CI) as compared to the non-neoplastic salivary gland tissue (4.11 +/- 0.90; 95% CI). The c-erbB-2 expression as measured by grain counts per cell for the pleomorphic adenomas (16.29 +/- 1.87; 95% CI), mucoepidermoid carcinomas (31.52 +/- 0.08; 95% CI) and the acinic cell carcinomas (44.24 +/- 17.11; 95% CI) were significantly greater than the expression for the normal group. The acinic cell carcinomas exhibited the greatest level of expression. As observed at the individual cell level, the autoradiographic signal was distributed uniformly in the neoplastic tissues, regardless of the cell type. This study confirms the hypothesis that the c-erbB-2 oncogene is overexpressed at the mRNA level in salivary gland tumours.