CD44 Standard and Variants Expression in Keratinocytic Tumor

Ko, Jae Won; Suh, Kee Suck; Kim, Sang Tae

Abstract

BACKGROUND: The CD44 antigen is a widely distributed cell surface glycoprotein implicated in multiple physiological cellular functions including cell-cell adhesion, cell-substrate interaction and cell activation. In the skin, CD44 is normally expressed in epidermal keratinocytes and hair follicular, sebaceous and eccrine epithelial cells. The precise functions of CD44 are not yet clearly understood, though they appear to be involved in the mechanism of tumor invasion and metastasis.
OBJECTIVE
The purpose of this study is to investigate the immunohistochemical expression of the CD44 molecule in the epidermal keratinocytic tumors with different biologic behaviors, such as squamous cell carcinoma(SCC),basal cell epithelioma(BCE), actinic keratosis(AK), bowen's disease, keratoacanthoma(KA), trichoepithelioma. METHODS: Routine paraffin sections of formalin-fixed 33 tissues (15 SCC, 23 BCE, 9 AK, 7 KA, 7 bowen's disease, 5 trichoepithelioma, 2 psoriasis, 2 lichen planus) were labeled with anti-CD44 monoclonal antibody using avidin-biotin- peroxidase complex. Normal skin served as the negative control.
RESULTS
The results are as follows. 1. In SCC and KA, peripheral parts of the lesion were prominently stained. CD44v6 showed the strongest expression, followed by CD44s and CD44v4/5. The horn cyst and the keratin region of the horn pearl were not stained. The degree of staining was weaker in KA compared to SCC. 2. The degree of staining was weaker in BCC and TEE compared to SCC. The staining was more prominent at the center of the lesion than in the peripheral region. In TEE, stronger staining was found at the center or in the squamous epithelial region. 3. Among the seven cases of Bowen's disease, 4 cases were diffusely stained with all three CD44 types. In the other three cases, local staining with the standard type and diffuse staining with CD44v4/5 and CD44v6 were seen. 4. In AK, the early lesion showed decreased expression of CD44 in all three types. However, those with mature lesion and progression to SCC showed increased degree of staining in all three types of CD44.
CONCLUSION
These results suggest that expression of CD44 in these keratinocytic tumors is not related to malignant transformation and metastasis, but instead may be related tumor differentiation.