Serum-dependent "cannibalism" and autodestruction in cultures of human small cell carcinoma of the lung.

In cell lines of human small cell carcinoma of the lung (SCCL) and in all subclones of one of the cell lines, cells were observed which completely interiorized other cells, leading to death of the interiorized cells and sometimes to complete autodestruction of the cultures. This phenomenon, which we have called "cannibalism," is also observed in fresh tumor biopsies from SCCL patients. Cannibalistic cells appeared to be of SCCL origin. "Cannibalism" is never observed in serum-free cultures but can be reinduced by serum exposure. It is likely that "cannibalism" may contribute to the frequent failure to establish SCCL cell lines in serum-containing medium. The potential to induce autodestruction of tumor cells in SCCL patients by as yet unknown serum factor(s) may be of therapeutic value.