Human achaete-scute homologue 1 (HASH-1) is downregulated in differentiating neuroblastoma cells

The mammalian achaete-scute homologue, MASH-1, is crucial for early develop ment of the sympathetic nervous system and is transiently expressed in symp athetic neuroblasts during embryogenesis. Here we report that the human hom ologue (HASH-1) was expressed in all analyzed cell lines (6/6) derived from the sympathetic nervous system tumor neuroblastoma. The majority of small- cell lung carcinoma (4/5) cell lines tested expressed HASH-1, while other n onneuronal/non-neuroendocrine cell lines were negative. Induced differentia tion of neuroblastoma cells resulted in HASH-1 down-regulation. This occurr ed concomitant with induction of neurite outgrowth and expression of the ne uronal marker genes GAP-43 and neuropeptide Y. Constitutive expression of e xogenous HASH-1 did not alter the capacity of the neuroblastoma cells to di fferentiate in response to differentiation-inducing agents. It is concluded that moderate HASH-1 expression does not compromise the capacity of these cells to differentiate. (C) 1999 Academic Press.