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.

Polymorphisms in BER genes and risk of breast cancer: evidences from 69 studies with 33760 cases and 33252 controls.

Recently, numerous studies have reported an association between single nucleotide polymorphisms in base-excision repair genes and the risk of developing breast cancer, however there is no consensus. The aim of this meta-analysis was to review and quantitatively assess the relationship between single nucleotide polymorphisms in base-excision repair genes and breast cancer risk. The results suggested that a mutation of T to G in rs1760944 may lead to a higher risk of developing breast cancer in the Mongoloid population, and G to A of rs25487 significantly reduced the risk of breast cancer in Mongoloid and Caucasoid populations. In contrast to the CC and CG genotypes, the GG genotype of rs1052133 located on theOGG1 gene appeared to be a protective factor against developing breast cancer in both Mongoloid and Caucasoid populations. There was no evidence to suggest that rs25489, rs1799782, rs1130409, rs1805414 and rs1136410 were associated with breast cancer risk. In conclusion, this study provides evidence to support the theory that DNA repair genes are associated with breast cancer risk, providing information to further understand breast cancer etiology. and The potential biological pathways linking DNA repair, ethnic background, environment and breast cancer require further investigation.