ALTERED EXPRESSION OF THE HEMIDESMOSOME-ANCHORING FILAMENT COMPLEX PROTEINS IN BASAL-CELL CARCINOMA - POSSIBLE ROLE IN THE ORIGIN OF PERITUMORAL LACUNAE

Basal cell carcinoma (BCC) is a frequent skin cancer with low metastat ic potential. Expression of the anchoring filament proteins, native la minin-5 and its individual alpha(3), beta(3) and gamma(2) chains, unce in, and linear IgA antigen was examined by immunostaining in 17 BCC wi th different histological subtypes, Immunoreactivity of the hemidesmos omal proteins, integrin alpha(6) beta(4), 230-kDa bullous pemphigoid a ntigen (BP-230 Ag) and plectin/HD-1, and that of dermal-epidermal junc tion (DEJ) components, integrin alpha(2) beta(1), laminin-1, collagen IV, and collagen VII was also analysed. Around tumour nests, the label ling of laminin-5 was absent or markedly reduced in 12 BCC (comprising eight solid BCC, three adenoid BCC and one keratotic BCC) and strong in five BCC (comprising three adenoid BCC, one keratotic BCC and one a denoid and keratotic BCC). Intriguingly, in tumour cells of 12 BCC inc luding laminin-5 negative tumours, a cytoplasmic reactivity of the lam inin gamma(2) chain was detected, but not that of the alpha(3) and bet a(3) chains. In the basement membrane of the epidermis overlying tumou r nests, the labelling of laminin-5 was always strong. Uncein, linear IgA disease antigen, and integrin alpha(6) beta(4) were absent in soli d BCC and weakly expressed in adenoid or keratotic BCC. For plectin/HD -1 and BP-230 Ag, a cytoplasmic reactivity was detected in the majorit y of the tumour cells. The labelling of integrin alpha(2) beta(1), lam inin-1, collagen IV and collagen VII indicated no alteration in the sy nthesis of these proteins. In peritumoral lacunae, immunoreactivity of hemidesmosome and anchoring filament proteins was absent, except for plectin/HD-1 on the tumour side and sometimes for laminin-5 on the str omal side, while laminin-1, collagen TV and collagen VII were detected on the stromal side. These findings suggest that the components of th e hemidesmosome-anchoring filament complex are not synthetized or asse mbled properly in BCC, and that the alteration of these adhesion struc tures may be the cause of peritumoral lacunae.