Mitoxantrone inhibits HIF-1α expression in a topoisomerase II-independent pathway.

Solid tumors encounter a growth-limiting hypoxic microenvironment as they develop. Hypoxia-inducible factors (HIF) play important roles in hypoxia-associated tumor development and therapeutic resistance. Targeting the HIF pathway (especially HIF-1α) represents a promising cancer treatment strategy. Here, we report a novel class of HIF-1α inhibitors and the possible molecular basis of inhibition. We analyzed the inhibitory effects of clinically used topoisomerase II (TOP2)-targeting drugs on HIF-1α expression with a primary focus on mitoxantrone. The potential role of TOP2 in mitoxantrone-inhibited HIF-1α expression was studied using pharmacologic inhibition, a knockdown approach, and TOP2 mutant cells. Moreover, involvement of mitoxantrone in proteasome-mediated degradation, transcription, and translation of HIF-1α was examined. The TOP2-targeting mitoxantrone, but neither doxorubicin nor etoposide (VP-16), strongly inhibited HIF-1α expression under hypoxic conditions in a dose- and time-dependent manner. Surprisingly, the mitoxantrone-mediated inhibition of HIF-1α expression was largely independent of two TOP2 isozymes, proteasomal degradation, and transcription. Furthermore, mitoxantrone inhibited HIF-1α expression and function in a similar fashion as cycloheximide, suggesting that mitoxantrone might inhibit HIF-1α via a blockage at its translation step. In vitro translation experiments using HIF-1α mRNA further confirmed inhibition of HIF-1α translation by mitoxantrone. Interestingly, levels of the polysome-bound HIF-1α and VEGF-A mRNA were elevated and decreased after mitoxantrone treatment, respectively. We have identified the TOP2-targeting compound, mitoxantrone, as an HIF-1α inhibitor possibly through a translation inhibition mechanism, suggesting the possibility of an additional anticancer activity for mitoxantrone.

Toh YM ，Li TK 《-》

Cell type-specific, topoisomerase II-dependent inhibition of hypoxia-inducible factor-1alpha protein accumulation by NSC 644221.

Creighton-Gutteridge M ，Cardellina JH 2nd ，Stephen AG ，Rapisarda A ，Uranchimeg B ，Hite K ，Denny WA ，Shoemaker RH ，Melillo G ... -  《CLINICAL CANCER RESEARCH》

UVC inhibits HIF-1alpha protein translation by a DNA damage- and topoisomerase I-independent pathway.

Rapisarda A ，Melillo G 《ONCOGENE》

D-glucosamine down-regulates HIF-1alpha through inhibition of protein translation in DU145 prostate cancer cells.

Park JY ，Park JW ，Suh SI ，Baek WK ... -  《-》

Silibinin inhibits expression of HIF-1alpha through suppression of protein translation in prostate cancer cells.

Jung HJ ，Park JW ，Lee JS ，Lee SR ，Jang BC ，Suh SI ，Suh MH ，Baek WK ... -  《-》