Purpose: Of the various microtubule-associated molecules, beta-tubulin III has been reported to be closely associated with the therapeutic efficacy of taxane-based chemotherapy against ovarian cancer. Stathmin and microtubule-associated protein 4 (MAP4) have been reported to play an important role in microtubule stabilization. In this study, we investigated whether expression of these microtubule-associated factors affects the therapeutic efficacy of taxane-based chemotherapy in ovarian clear cell adenocarcinoma.
Experimental design: Drug sensitivity of paclitaxel or cisplatin was assessed in ovarian cancer cell lines treated with small interfering RNA of tubulin isoforms, MAP4, and stathmin. We examined 94 surgically resected ovarian clear cell adenocarcinoma specimens from patients treated with taxane-containing regimens (n=44) and with taxane-free regimens (n=50), using immunohistochemistry to detect expression of beta-tubulin III, stathmin, and MAP4.
Results: Knockdown of beta-tubulin III and IV specifically conferred drug resistance to paclitaxel in one ovarian cancer cell line, but not to other molecules. Estimated overall survival revealed a significant synergistic effect between taxane and beta-tubulin III in patients with ovarian clear cell adenocarcinoma. Of three microtubule-related molecules, among the taxane-based chemotherapy group, cases with higher beta-tubulin III expression were associated with a significantly more favorable prognosis compared with those having lower beta-tubulin III expression. By contrast, there was no statistical significance in the synergistic relationships between stathmin and taxane or between MAP4 and taxane.
Conclusions: Taxane-based chemotherapy was effective for patients with ovarian clear cell adenocarcinomas who were positive for beta-tubulin III but not for those who were negative for these proteins.