Tubulin Proteomics in Cancer

Human tubulin α/β heterodimers are encoded by six and seven genes for the α- and β-subunit, respectively. Each of these isotypes can undergo various posttranslational modifications. Most of the sequence specificity for each isotype and posttranslational modifications occur at the C-terminal part of tubulin. The biological significance of this so-called “tubulin code” and its regulation are unresolved questions in basic cytoskeleton research and in pathologies such as cancer. βIII-tubulin repeatedly appears as a potential marker of poor prognosis in different tumor types and of drug resistance. Nevertheless, because of limitations in present methods of analysis, it is still unclear if tubulin isotype expression profiles will provide useful biomarkers for the stratification of cancer patients prior to treatments including microtubulo-interacting drugs. Recent progresses in mass spectrometry-based analyses of tubulin isotype expression in cancer cells are presented in this chapter. Such approaches allow the validation of tools such as antibodies used in immunohistochemistry, identifies tubulin sequences expressed in human cells and posttranslational modifications, and offer new avenues for tubulin isotype quantitation in tumor and normal tissues.