Oncogenic dysregulation of pre-mRNA processing by protein kinases: challenges and therapeutic opportunities

Alternative splicing and polyadenylation represent two major steps in premRNA-processing, which ensure proper gene expression and diversificationof human transcriptomes. Deregulation of these processes contributes to oncogenic programmes involved in the onset, progression and evolution ofhuman cancers, which often result in the acquisition of resistance to existingtherapies. On the other hand, cancer cells frequently increase their transcriptionalrate and develop a transcriptional addiction, which imposes ahigh stress on the pre-mRNA-processing machinery and establishes a therapeuticallyexploitable vulnerability. A prominent role in fine-tuning premRNA- processing mechanisms is played by three main families of protein kinases: serine arginine protein kinase (SRPK), CDC-like kinase (CLK) and cyclin-dependent kinase (CDK). These kinases phosphorylate the RNA polymerase, splicing factors and regulatory proteins involved in cleavage and polyadenylation of the nascent transcripts. The activity of SRPKs, CLKs and CDKs can be altered in cancer cells, and their inhibition was shown to exert anticancer effects. In this review, we describe key findings that have been reported on these topics and discuss challenges and opportunities of developing therapeutic approaches targeting splicing factor kinases.