Expression of alpha-crystallins in human sebaceous carcinoma of the eyelid

Abstract

Purpose: Crystallins are molecular chaperones that protect various cells from apoptosis. This study used immunohistochemistry to examine the expression of alphaA-crystallin and alphaB-crystallin in human sebaceous carcinoma tissues.

Methods: Nine patients with sebaceous carcinoma of the eyelid underwent excision of the eyelid or orbital exenteration. Formalin-fixed, paraffin-embedded tissue sections were submitted for hematoxylin-eosin staining and immunohistochemistry with anti-alphaA- and alphaB-crystallin antibodies.

Results: In the noncancerous eyelid, crystallins were weakly and homogeneously expressed in the Meibomian gland lobules. In eyelids with sebaceous carcinoma, alphaA-crystallin and alphaB-crystallin were highly expressed in 4 cases, where the cytoplasmic immunoreactivity was heterogeneously detected in the tumor cells. Three and 2 cases were shown to express low levels of alphaA-crystallin and alphaB-crystallin, respectively. A statistically significant correlation was observed between expression levels of alphaA-crystallin and alphaB-crystallin in sebaceous carcinomas (p=0.012). All sebaceous carcinoma tissues contained mitotic tumor cells, which showed predominantly perinuclear immunoreactivity of alphaB-crystallin. The mitotic rate of tumor cells was 5.85+/-1.76 and 10.72+/-1.64 in high and moderate/low alphaB-crystallin-expressing cases, respectively. The number of mitotic cells was significantly higher in moderate/low alphaB-crystallin-positive than in high-positive cases (p<0.01).

Conclusions: Crystallins are expressed in human sebaceous carcinomas including mitotic cells. Expression of alphaB-crystallin correlated with low number of mitotic tumor cells, suggesting that alphaB-crystallin may play a potential role in the regulation of tumor cell proliferation.

Fig. 1

DAPI nuclear staining (A, C, D, F; blue) and immunoreactivity for αA-crystallin (B, C; green) and αB-crystallin (E, F; green) in normal human Meibomian glands. Normal glands weakly express αA-crystallin in the lobules (green; A–C). Immunoreactivity for αB-crystallin is barely detected in the glands (D–F)

Fig. 2

Hematoxylin-eosin (H–E) staining (A), DAPI nuclear staining (B, D, E, G; blue), and immunoreaction of αA-crystallin (C, D; green) and αB-crystallin (F, G; green) in human sebaceous gland carcinoma evaluated as a case showing high expression. H–E staining reveals sebaceous cell carcinoma, representing basophilic mass beneath the normal squamous epithelium of the eyelid (A). αA-crystallin is heterogeneously expressed in higher levels than normal squamous epithelium (B–D). αB-crystallin immunoreactivity is strongly detected in the cytoplasm of tumor cells (E–G).

Fig. 3

Hematoxylin-eosin (H–E) staining (A), DAPI nuclear staining (B, D, E, G; blue), and immunoreaction of αB-crystallin (C, D; green) and αA-crystallin (F, G; green) in mitotic cells of sebaceous gland carcinoma. H–E staining (A; arrow) and DAPI nuclear staining (B, D, E, G; arrow) show mitotic tumor cells in sebaceous cell carcinoma. The merged image shows the αB-crystallin to be highly expressed in perinuclear mitotic cells (B–D). The merged image represents αA-crystallin to be less expressed than αB-crystallin (E–G).