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

The mammalian achaete-scute homologue, MASH-1, is crucial for early development of the sympathetic nervous system and is transiently expressed in sympathetic neuroblasts during embryogenesis. Here we report that the human homologue (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 nonneuronal/non-neuroendocrine cell lines were negative. Induced differentiation of neuroblastoma cells resulted in HASH-1 downregulation. This occurred concomitant with induction of neurite outgrowth and expression of the neuronal marker genes GAP-43 and neuropeptide Y. Constitutive expression of exogenous HASH-1 did not alter the capacity of the neuroblastoma cells to differentiate in response to differentiation-inducing agents. It is concluded that moderate HASH-1 expression does not compromise the capacity of these cells to differentiate.