Biomedical subjects

A Grynfeld

Publications and source records attributed to A Grynfeld.

3 recordsLinked to original sources

PubMed2000

Induced neuroblastoma cell differentiation, associated with transient HES-1 activity and reduced HASH-1 expression, is inhibited by Notch1.

Neuroblastoma is a childhood tumor that originates from the sympathetic nervous system. The tumor cells have embryonic features, presumably as a consequence of an impaired capacity to respond to signals and transcriptional control mechanisms operating during normal differentiation. Two basic helix-loop-helix transcription factors, human achaete-scute homologue-1 (HASH-1) and hairy/enhancer of split homologue-1 (HES-1), are crucial for proper development of some neuronal cells. Here, their potential roles during sympathetic differentiation of human neuroblastoma cells have been investigated. In all tested protocols for induction of differentiation of SH-SY5Y and SK-N-BE(2) neuroblastoma cells, HASH-1 expression was rapidly decreased with a concomitant, often transient, increase in HES-1 expression. In gel mobility shift assays, using extracts from neuroblastoma cells, HES-1 bound to an oligonucleotide corresponding to a sequence in the HASH-1 promoter including the so-called N-box, suggesting that the transiently increased HES-1 activity in differentiating neuroblastoma cells is involved in down-regulation of HASH-1. Constitutive expression of the intracellular domain of Notch1, which activates the HES-1 promoter in SH-SY5Y cells, inhibited spontaneous and induced morphological differentiation of these neuroblastoma cells. Our data show that functional sympathetic neuronal differentiation of neuroblastoma cells is associated with transient activation of HES-1 and down-regulation of HASH-1 expression.

Basic Helix-Loop-Helix Proteins↗

PubMed2000

HASH-1 and E2-2 are expressed in human neuroblastoma cells and form a functional complex.

The basic helix-loop-helix (bHLH) transcription factor mammalian achaete-scute homolog-1 (MASH-1 in mouse and HASH-1 in human) is essential for proper development of olfactory and most peripheral autonomic neurons, and for the formation of distinct neuronal circuits within the central nervous system. We have previously shown that HASH-1 is expressed in neuroblastoma tumors and cell lines, and in this study we have used the yeast two-hybrid system to isolate HASH-1 interacting proteins from a human neuroblastoma cDNA library. Two of the isolated clones contained cDNA from the E2-2 gene (also known as ITF2/SEF2-1). We show that E2-2 interacts with HASH-1 in both yeast and mammalian cells. The HASH-1/E2-2 complex binds an E-box (CACCTG) in vitro, and transactivates an E-box containing reporter construct in vivo. Furthermore, E2-2 seems to be one of the major HASH-1 interacting proteins in extracts from neuroblastoma cells. In conclusion, E2-2 forms a functional complex with HASH-1, and might therefore be involved in the development of specific parts of the central and peripheral nervous systems.

Basic Helix-Loop-Helix Leucine Zipper Transcriptio↗

PubMed1999

The basic helix-loop-helix transcription factor dHAND, a marker gene for the developing human sympathetic nervous system, is expressed in both high- and low-stage neuroblastomas.

Neuroblastoma is derived from the sympathetic nervous system and might arise as a result of impaired differentiation, retaining the neuroblastic tumor cells in the cell cycle. Thus, to understand the genesis of neuroblastoma, the study of mechanisms and genes regulating normal sympathetic development is of potential interest. The basic helix-loop-helix transcription factors human achaete-scute homolog-1 (HASH-1) and deciduum, heart, autonomic nervous system, and neural crest derivatives (dHAND) are expressed in the sympathetic nervous system of embryonic mice and chicken, with undetectable postnatal expression. By in situ hybridization technique, we show that dHAND was expressed by human sympathetic neuronal and extra-adrenal chromaffin cells throughout embryonic and fetal life, and was initially expressed in immature chromaffin cells of the adrenal gland. With overt chromaffin differentiation, dHAND was down-regulated. HASH-1, in contrast, was expressed in human sympathetic cells only at the earliest embryonic ages examined (Week 6.5 to 7). All examined neuroblastoma specimens (25/25) and all cell lines (5/5) had detectable dHAND mRNA levels. HASH-1 expression in tumor specimens was more restricted, although all cell lines (5/5) were HASH-1-positive. These results show that neuroblastoma tumors have retained embryonic features, suggesting that many neuroblastomas are blocked at an early stage of normal development when HASH-1 and dHAND are expressed. dHAND also appears to be a reliable and potentially useful clinical diagnostic marker for neuroblastoma, because expression was not dependent on tumor or differentiation stages and other pediatric tumors were dHAND-negative.

Animals↗