M. Makinen et al., EPIDERMAL-CELL ADHESION AND BASEMENT-MEMBRANE ALTERATIONS IN EXPERIMENTAL SKIN TUMOR-DEVELOPMENT, Anticancer research, 18(2A), 1998, pp. 877-884
Background: Epidermal cell adhesion and basement membrane (BM) are ess
ential for the differentiated structure of squamous epithelium, and bo
th are reduced in malignant tumours. Materials and Methods: We analyse
d the expression of cell adhesion-related proteins desmoplakin and E-c
adherin, BM components laminin and collagen IV, and BM receptor integr
in a6 in experimental preneoplastic changes and neoplasms of skin. Dif
ferent mouse strains (NMRI, C57Bl/6 and DBA/2) and exposure protocols
(DMBA, UV, DMBA + UV) were used to find possible differences in the ex
pression of cell adhesion and BM proteins within individual tumonr typ
es. Results: The individual strain had an impressive role on the expre
ssion of tumors. The exposure model affected the type of tumour found
and tumour behaviour: The location and expression of cell attachment p
roteins were dependent on morphology, brit mouse str ain and type of e
xposure had no effect. The decline in the expression of markers studie
d was gradual involving the cytoplasmic immunoreactivity of integrin a
6 and laminin observed in dysplastic epidermis, BM structure formation
becoming increasingly disturbed in dysplasia; this was present in squ
amous cell carcinomas and absent in undifferentiated tumours. Desmopla
kin expression gradually disappeared during the decline in differentia
tion. E-cadherin expression was preserved longer, and disappeared alon
g with the loss of squamous properties. Conclusions: Desmoplakin and E
-cadherin served in this study as differentiation markers. None of the
se proteins seem to explain the differences in the tumonr sensitivity
of individual mouse strains.