Protein expression in humans is controlled by numerous RNA processing steps that occur between transcription of a gene and translation of protein. However, the importance of such regulatory steps to human diseases, especially cancer, is just now coming to light. Changes in the alternative splicing or stability of mRNA transcribed from genes involved in cell-cycle control, cell proliferation, and apoptosis has been linked to tumor formation and progression. Nevertheless, in the majority of these cases, the identity of the regulators that control the expression of such cancer-related genes is poorly understood. In this issue of the JCI, Goehe et al. demonstrate that heterogeneous nuclear ribonuclear protein family member L (hnRNP L), a member of the hnRNP family of RNA processing factors, is specifically phosphorylated in non–small cell lung cancer (NSCLC). The phosphorylated hnRNP L, in turn, promotes expression of the antiapoptotic form of caspase-9, thereby contributing to tumorigenesis.
Ganesh Shankarling, Kristen W. Lynch
Model for the regulation of caspase-9 mRNA expression by hnRNP L.