CONTRACTILE PROTEINS IN HUMAN CANCER-CELLS - IMMUNOFLUORESCENT AND ELECTRON-MICROSCOPIC STUDY

Abstract

The presence of contractile proteins in human cancer cells was studied by immunofluorescent staining using specific antibodies, and EM to detect the presence of cytoplasmic filaments. The tissues examined were normal human skin, basal cell carcinoma of the skin, squamous cell carcinomas (of skin, oral cavity and larynx), normal nonlactating mammary gland and infiltrating mammary carcinoma, with or without fibrosis. Normal tissues were negative after immunofluroescent staining of contractile proteins and contained no or minimal amounts of microfilaments as judged by EM. Tumor cells were strongly positive after immunoflouorescent staining for actin, actinin, myosin, light and heavy meromyosin, but were negative for tropomyosin. They also contained prominent microfilaments (40-80 .ANG. in diameter) with some filaments (100-120 .ANG. in diameter) scattered in between. It appears that malignant cells contain an increased amount of contractile proteins, organized in the form of a filamentous apparatus, when compared to their normal counterparts. The study of the presence of contractile proteins in tumor cells may be of potential importance in evaluating malignant growth.