Objective: To observe the expression and distribution of CD44, CD133, and ABCG2 in orbital adenoid cystic carcinoma (ACC) and investigate their correlations with pathological type and prognosis.
Method: Two steps method of immunohistochemical staining was employed in 33 cases of paraffin embedded surgical specimens of human orbital ACC, 5 cases of recurrence samples, 3 cases of an excised lacrimal gland caused by neither inflammation nor tumor diseases, and 6 cases of xenograft tumors in nude mice. A retrospective analysis was performed on the clinical material of these patients, which were collected from Jan. 1991 to Mar. 2009.
Results: The positive rate of CD44 was 54.5% (18/33), with 76.9% (10/13) in solid type and 40.0% (8/20) in adeno-tubiform type. There was no statistically significant difference between them (P = 0.072). In solid type the positive expression cells were often located at the marginal part of the cancer nest. In the adeno-tubiform type, positive cells were often located at the outer layer of the tubiform structure (myoepithelial cells). CD44 was also expressed in normal tissues. The positive rate of CD133 was 57.6% (19/33), with 76.9% (10/13) in solid type and 45.0% (9/20) in adeno-tubiform type. There was no significant difference between them (P = 0.087). CD133 antigen was expressed in either the cytoplasm or nucleus, or expressed in both the cytoplasm and nucleus. The positive rate of ABCG2 was 21.2% (7/33), with 30.77% (4/13) in solid type and 15.0% (3/20) in adeno-tubiform type. There was no significant difference between them (P = 0.393). Many positive cells surrounded the vessels in tumor tissues. There were no significant differences between different prognosis groups of these surface phenotypes. The correlative analysis results of three surface phenotypes showed that CD44(+) cells have positive correlation with CD133(+) cells (Spearman, r(s) = 0.416, P = 0.016). In six transplanted tumors of nude mice, the number of positive cases for CD44(+), CD133(+) and ABCG2(+) was 1, 1 and 4 cases, respectively.
Conclusions: The expression of CD44, CD133 and ABCG2 in ACC may influence the progress of ACC. However, they cannot be used as the markers for the evaluation of the prognosis of this tumor.