SENP2 suppresses NF-κB activation and sensitizes breast cancer cells to doxorubicin

Doxorubicin is a chemotherapeutic agent commonly used to treat breast cancer. However, breast cancer often develops drug resistance, leading to disease recurrence and poor prognosis. Delineating the mechanisms underlying drug resistance is imperative for overcoming the challenge of treating doxorubicin-resistant breast cancer. In this study, by identifying the possible role of Sentrin/SUMO-specific proteases (SENPs) in doxorubicin resistance, we show here that among the 6 members of SENPs, only SENP2 is downregulated in doxorubicin-resistant MCF-7 (MCF-7/adr) and MDA-MB-231 (dr) breast cancer cells, as compared with sensitive counterparts. In addition, functionally, SENP2 overexpression resensitizes resistant breast cancer cells to doxorubicin treatment, and its knockdown confers doxorubicin resistance in sensitive ones. Moreover, NF-κB pathway is activated in MCF-7/adr cells, however, treatment with Bay 11-7085, one specific inhibitor of this pathway, reverses resistance to doxorubicin, suggesting that NF-κB pathway activation contributes to doxorubicin resistance in MCF-7/adr cells. We further show that SENP2 overexpression enhances NEMO deSUMOylation and suppresses NF-κB activation particularly in MCF-7/adr cells. Furthermore, SENP2 overexpression-induced sensitivity of MCF-7/adr cells to doxorubicin is drastically abrogated when treated with NF-κB pathway activator, thus establishing a causal link between SENP2-suppressed NF-κB pathway and enhanced doxorubicin sensitivity in breast cancer cells. Overall, this study reveals a novel function of SENP2 in counteracting doxorubicin resistance in breast cancer, and highlights the critical role of NF-κB suppression in mediating this effect.