NF?BP65 transcription factor modulates resistance to doxorubicin through ABC transporters in breast cancer

Abstract

Background: Shedding light on chemoresistance biology of breast cancer could contribute to enhance the clinical outcome. Intrinsic or acquired resistance to chemotherapy is a major problem in breast cancer treatment. Methods and materials: The NF?B pathway by siRNAP65 and JSH-23 as a translocational inhibitor of NF?BP65 in the doxorubicin-resistant MCF-7 (MCF-7/Dox) and MCF-7 cells was blocked. Then, the ABC transporter expression and function were assessed by real-time qRT-PCR and flow cytometry, respectively. Induction of apoptosis was evaluated after inhibition of the NF?B pathway as well. Results: Our study underlined the upregulation of NF?BP65 and anti-apoptotic Bcl-2 and downregulation of pro-apoptotic Bax in the MCF-7/Dox cells compared with control MCF-7 cells. Here, we showed that interplay between nuclear factor kappa B P65 (NFkBP65) as a transcriptional regulator and ABC transporters in the MCF-7/Dox cancer cells. We found that inhibition of the elevated expression of NF?BP65 in the resistant breast cancer, whether translocational inhibition or silencing by siRNA, decreased the expression and function of MDR1 and MRP1 efflux pumps. Furthermore, the blockade of NF?BP65 promoted apoptosis via modulating Bcl-2 and BAX expression. After inhibition of the NF?BP65 signaling pathway, elevated baseline expression of survival Bcl-2 gene in the resistant breast cells significantly decreased. Conclusion: Suppression of the NF?B pathway has a profound dual impact on promoting the intrinsic apoptotic pathway and reducing ABC transporter function and expression, which are some of the chemoresistance features. It was speculated that the NF?B pathway directly acts on doxorubicin-induced MDR1 and MRP1 expression in MCF-7/Dox cells. © 2016, The Japanese Breast Cancer Society.