Tumor‐Associated glycoprotein expression in salivary gland mucoepidermoid carcinomas: An immunohistochemical study using the monoclonal antibody B72.3

Abstract

The monoclonal antibody B72.3 recognizes a mucin-like glycoprotein which is expressed in a variety of human malignancies including adenocarcinomas of the breast, colon, lung, endometrium, pancreas, and ovary. The antibody, an immunoglobulin G (IgG1) subclass monoclonal antibody, was generated from membrane-enriched fractions of metastatic mammary carcinoma. Because the antigen detected by B72.3 is expressed in a broad spectrum of human neoplasms, B72.3 is a potentially useful marker for glandular neoplasms. Despite its potential usefulness, there is only one previous comprehensive study which has examined the distribution of the tumor-associated glycoprotein (TAG-72), as detected by B72.3, in salivary neoplasms. We examined 21 mucoepidermoid carcinomas with the antibody. Twenty (95%) of the 21 carcinomas stained positively. The only carcinoma that did not stain was initially thought to be a high-grade mucoepidermoid carcinoma based on immunohistochemical staining. Further review, however, indicated that this lesion was most likely a pure squamous cell carcinoma, and the absence of TAG-72 antigen expression was helpful in this regard. Among those neoplasms which stained with B72.3, the strongest staining was seen in the low-grade carcinomas. These results suggest that B72.3 may be a useful marker for glandular differentiation in mucoepidermoid carcinomas.

Tumor‐Associated Glycoprotein (TAG‐72) in Chronic Submandibular Sialadenitis and Normal Minor Salivary Glands Defined by Monoclonal Antibody B72.3

“…Brandwein et al 10 found that the normal parotid gland does not express TAG‐72 in contrast to its tumors, and future studies with radiolabeled Mab B72.3 to determine its possible usefulness in immunotherapy and radiation immunolocalization were suggested. A similar suggestion was proposed by Roa et al 11 for the possible use of the Mab B72.3 in immunotherapy and radioimmunodiagnosis of recurrent or metastatic mucoepidermoid carcinoma in the parotid and submandibular regions. We suggest that the focal expression of TAG‐72 in normal submandibular gland and the diffuse expression in chronic submandibular sialadenitis should be considered in these future studies.…”

“…The expression of TAG‐72 has been studied in many salivary gland tumors, in normal parotid gland, and in two cases of chronic submandibular sialadenitis 9‐11 …”

MUC1, MUC2, MUC4, and MUC5AC Expression in Salivary Gland Mucoepidermoid Carcinoma

“…Although our work does not show data to support this hypothesis, we speculate that histochemical staining may fail to detect underglycosylated forms of mucins, a possible occurrence in cancer cells, but that underglycosylated forms can be recognized by antibodies reactive with the protein part of the mucins. As a practical matter, immunohistochemical staining for MUC5AC can be used for the diagnosis of high-grade MECs together with other markers that have been proposed as diagnostic tools such as CK7 as suggested by Nikitakis et al, 20 or the mucin-carriedsialylated-Tn epitope that is reactive with monoclonal antibody B72.3 as suggested by Roa et al 24 Staining for MUC1 may be useful for identifying cases with a better prognosis as shown in this paper. Strikingly, in our study none of the cases completely lacking MUC1 expression experienced an unfavorable event such as recurrence, metastasis, or death-related cancer, with a follow-up period during which these events occurred frequently in the MUC1-positive group.…”

Salivary Mucoepidermoid Carcinoma: Revisited

“…43 Immunoreactivity to monoclonal antibody B72.3 was strongest in MECs with prominent glandular differentiation. 44 MECs usually express, in different proportions, MUC1, MUC4, MUC5AC, and MUC5B; less frequently express MUC6; and rarely express MUC2 and MUC7. 45,46 The immunohistochemical staining pattern of CK is not associated with the histologic grade of differentiation, 47 whereas high MUC1 expression is related to a high histologic grade, high recurrence and metastasis rates, and a short disease-free interval.…”