ECTOPIC EXPRESSION OF C-KIT IN SMALL-CELL LUNG-CANCER

Accumulating evidence suggests that c-kit plays an important role in t he regulation of growth of at least 3 lineages of stem cells, while on ly very limited data are available on the development of human solid t umors. Our recent studies have shown that c-kit transcripts are expres sed in a very restricted sub-set of human solid tumors such as small-c ell lung cancer (SCLC). We have also conducted an immunohistological s tudy on in situ localization of the c-kit protein in various human sol id tumors as well as in corresponding fetal and adult normal tissues. No c-kit expression was detected in normal bronchial epithelial cells or pneumocytes in lung parenchyma of human fetal and adult specimens, indicating that the c-kit protein is aberrantly expressed in lung-canc er cells. We also found that significant chemotactic response as well as moderate in vitro cell growth occurred in SCLC cell lines upon addi tion of recombinant human stem-cell factor. (C) 1994 Wiley-Liss, Inc.