RESUMEN
Tubulin is a heterodimer of α and ß subunits, both existing as isotypes differing in amino acid sequence encoded by different genes. Specific isotypes of tubulin have associations with cancer that are not well understood. Previous studies found that ßII-tubulin is expressed in a number of transformed cells and that this isotype is found in cell nuclei in non-microtubule form. The association of ßII expression and its nuclear localization with cancer progression has not previously been addressed. We here used a monoclonal antibody to ßII to examine patients with colorectal cancer and found that patients whose tumors over-express ßII have a greatly decreased life expectancy which is even shorter in those patients with nuclear ßII. Our results suggest that ßII-tubulin may facilitate cancer growth and metastasis and, to accomplish this, may not need to be in microtubule form. Furthermore, ßII expression and localization could be a useful prognostic marker. We also found that ßII appears in the nuclei of otherwise normal cells adjacent to the tumor. It is possible therefore that cancer cells expressing ßII influence nearby cells to do the same and to localize ßII in their nuclei by an as yet uncharacterized regulatory pathway.