Regulation of tubulin expression by micro-RNAs: implications for drug resistance

In this chapter, we provide an overview of methods for studying micro-RNA regulation of tubulin isotypes. In clinical studies, β-tubulin isotypes were found to be biomarkers for tumor formation. In addition, because changes in the levels of specific β-tubulin isotypes alter the stability of microtubules in mitotic spindles in vitro, it has been hypothesized that changes in microtubule protein levels could contribute to chemotherapy resistance. Over the past 15 years, micro-RNAs have been shown to target mRNAs in signaling pathways involved in tumor suppression, as well as tumorigenesis. Investigating micro-RNA regulation of tubulin isotypes will shed light on the mechanisms underlying the processes that implicate tubulin isotypes as biomarkers for aggressive tumors or chemotherapy resistance. The methods discussed in this chapter include the use of micro-RNA superarrays, next-generation sequencing, real-time PCR experiments, upregulation of micro-RNAs, and immunoprecipitation of RNA-induced silencing complex. We will show examples of data collected using these methods and how these data contribute to understanding paclitaxel resistance.