Cultured human breast cancer cells lose selectivity in direct intercellular communication

Abstract

VARIOUS small molecules, up to 1,600 molecular weight¹, can pass directly between certain animal cells in contact, probably through gap junctions^2,3. Such communication may partly mediate growth control in multicellular organisms and cultured cells, so that disturbances in the normal pattern of communication could be related to malignant growth^4,5. The ³H-nucleotide transfer method⁶, based on metabolic cooperation⁷ has shown that communication is not always an all-or-none phenomenon, but may be selective^8,9. For example, human mammary epithelial cells from benign tumours or milk do not communicate with human breast fibroblasts (HumF), although either type can communicate well with homologous cells. We have examined the communication between cancer cells from several human breast cancer sources and found that, unlike normal mammary epithelium, they do not show selectivity in communication. The cancer cells fall into one or other of the two functional groups we have defined as non-selective communicators (communicate with all cells capable of communication) or non-communicators (unable to communicate with homologous or heterologous cells) suggesting that the change to malignancy involves some change in the pattern of cell communication.