[The contractile filament system of carcinoma cells. Immunofluorescent and electron microscopic study]

Recent research has shown that the cytoplasm of several varieties of non muscular cells contains contractile proteins similar to those of striated muscle (actin and myosin, with the control complex of troponin and tropomyosin). Using indirect immunofluorescent staining with specific antisera, the authors demonstrate that the cytoplasm of the cells of oral squamous cell carcinoma contains actin, myosin and actinin (tropomyosin seems to be lacking). They have found these contractile proteins inconstantly in various precarcinomatous states, but never in normal epithelium, except in a few basal cells. In electronic microscopy, these contractile proteins correspond to a network of microfilaments of 40-80 A, more rarely 100-120 A, Clearly different from tonofilaments, located mainly in the peripheral part of the cytoplasm, just under the plasmalemmal membrane. It is tempting to speculate that the occurence of a contractile filamentous apparatus in the cells of oral carcinomas--already described in skin and mammal gland carcinomas--allows to these cells amoeboid movements and active migration, which might to some extent explain their tendency to invade surrounding tissues and to produce metastasis.