SEPT9_V1 protein expression is associated with human cancer cell resistance to microtubule-disrupting agents.

SEPT9 is a mammalian septin family member. There is growing evidence that SEPT9 plays a role in cancer. The protein product, SEPT9_V1, associates with microtubules and interacts with hypoxia-inducible factor (HIF)-1alpha, the regulated subunit of the key transcription factor HIF-1. HIF-1 transcriptional activity is thoroughly dependent on intact microtubules. We tested the hypothesis that SEPT9_V1 confers resistance to microtubule-mediated HIF-1 inhibitors. SEPT9_V1 protein expression was strongly correlated with susceptibility of a wide range of cancer cells to 2-methoxyestradiol and paclitaxel. Our results revealed that SEPT9_V1 could serve as a biomarker for therapeutic resistance to microtubule disrupting agents.