RNA synthesis and processing as a measure of phenotypic variability in cytodifferentiation and neoplasia

Neoplastic cell lines exhibit RNA synthesis and process patterns which are related to phenotypic attributes more complex than merely the rate of proliferation. Mouse neuroblastoma cells of the same genotype but different differentiated states have different ribosomal RNA precursor processing patterns, while plasmacytoma cells of different genotypes but the same differentiated state have the same pre-ribosomal RNA processing pattern. In addition, our observations indicate that chromatin-associated RNA is involved in cytodifferentiation and is closely related to phenotypic variability. When neuroblastoma cells are induced to differentiate, there is a 2- to 3-fold increase in the labeling of chromatin-associated RNA. Both of the differentiated cell lines, human myeloma and mouse neuroblastoma, have slow-labeling, stable chromatin-associated RNA while this same fraction from HeLa cells is labeled rapidly and is unstable.