metribolone and Neuroblastoma

Spinal bulbar muscular atrophy (SBMA) is one of a family of inherited neurodegenerative diseases caused by expansion of CAG encoding polyglutamine repeats; in SBMA the affected gene is the androgen receptor. To understand further the mechanisms that lead to neuronal cell death in SBMA, we generated SHSY5Y neuroblastoma cell lines that stably express identical levels of wild-type (19 polyglutamine repeat) or SBMA (52 polyglutamine repeat) androgen receptor. Parental SHSY5Y cells do not express detectable levels of the androgen receptor. In the absence of androgen, the transfected cell lines have similar phenotypes and growth characteristics to parental SHSY5Y cells. However, upon treatment with androgen, both cell lines undergo a marked dose-dependent loss of viability; this loss was significantly greater in cells expressing the SBMA receptor. Morphological analyses of the androgen treated cells revealed that cell death bore hallmarks of apoptosis involving altered nuclear morphology and cleavage of poly(ADP-ribose) polymerase and of caspase 3 in both wild-type and SBMA cell lines. The caspase inhibitor VAD-fmk was able to decrease loss of viability of both cell lines on exposure to androgen.

Topics: Apoptosis; Cell Survival; Cells, Cultured; Genetic Vectors; Humans; Immunohistochemistry; Metribolone; Motor Neuron Disease; Mutation; Neuroblastoma; Receptors, Androgen; Testosterone Congeners; Transfection; Tumor Cells, Cultured

Polyglutamine tracts encoded by trinucleotide CAG repeats have been found in some transcription factors. Expansion of the polyglutamine tracts in the androgen receptor (AR) has been recognized as a cause of X-linked spinal and bulbar muscular atrophy (SBMA). To study the role of AR as a transcription factor in SBMA, we constructed AR genes encoding expanded polyglutamine tracts (repeat numbers = 52, 92, 132, and 212), and analyzed AR-induced transcriptional activation in NG108-15 cells. We found that AR-induced transcriptional activation gradually decreased with increasing glutamine repeat numbers, and polyglutamine expansion caused a specific reduction in transcription activity in motor neurons. However, the degree of reduction was slight in comparison with the normal AR gene and that of SBMA. Thus, subtle disorders of transcriptional control may occur in SBMA.

Topics: Animals; Base Sequence; Binding, Competitive; Blotting, Western; Choline O-Acetyltransferase; COS Cells; Gene Expression Regulation; Genetic Linkage; Glutamine; Hybrid Cells; Metribolone; Mice; Molecular Sequence Data; Muscular Atrophy, Spinal; Mutagenesis; Neuroblastoma; Receptors, Androgen; Repetitive Sequences, Nucleic Acid; Testosterone Congeners; Transcription, Genetic; X Chromosome