ETV7-Mediated DNAJC15 Repression Leads to Doxorubicin Resistance in Breast Cancer Cells

Abstract

Breast cancer treatment often includes Doxorubicin as adjuvant as well as neoadjuvant chemotherapy. Despite its cytotoxicity, cells can develop drug resistance to Doxorubicin. Uncovering pathways and mechanisms involved in drug resistance is an urgent and critical aim for breast cancer research oriented to improve treatment efficacy. Here we show that Doxorubicin and other chemotherapeutic drugs induce the expression of ETV7, a transcriptional repressor member of ETS family of transcription factors. The ETV7 expression led to DNAJC15 down-regulation, a co-chaperone protein whose low expression was previously associated with drug resistance in breast and ovarian cancer. There was a corresponding reduction in Doxorubicin sensitivity of MCF7 and MDA-MB-231 breast cancer cells. We identified the binding site for ETV7 within DNAJC15 promoter and we also found that DNA methylation may be a factor in ETV7-mediated DNAJC15 transcriptional repression. These findings of an inverse correlation between ETV7 and DNAJC15 expression in MCF7 cells in terms of Doxorubicin resistance, correlated well with treatment responses of breast cancer patients with recurrent disease, based on our analyses of reported genome-wide expression arrays. Moreover, we demonstrated that ETV7-mediated Doxorubicin-resistance involves increased Doxorubicin efflux via nuclear pumps, which could be rescued in part by DNAJC15 up-regulation. With this study, we propose a novel role for ETV7 in breast cancer, and we identify DNAJC15 as a new target gene responsible for ETV7-mediated Doxorubicin-resistance. A better understanding of the opposing impacts of Doxorubicin could improve the design of combinatorial adjuvant regimens with the aim of avoiding resistance and relapse.

Regulatory Crosstalk of Doxorubicin, Estradiol and TNFα Combined Treatment in Breast Cancer-derived Cell Lines

“…Cells were harvested 16 hours after the administration of the drugs. In previous experiments, we had shown similar results with both a 10-hour and a 16-hour treatment schedule 2,28 .…”

“…Previous studies showed the effect of E2 on p53 cellular localization and cell sensitivity to TNFα 1,11,27 . Treatment of MCF-7 with E2 decreases the transcription factor activity of p53 by transporting it to the cytoplasm, and subsequently, decreases the sensitivity to TNFα induced tumor suppressor effects 28 . In conclusion, these findings suggest that the combination treatment of Doxorubicin, E2 and TNFα may be involved in decreasing the expression and activity of ESR1 , potentially enhancing the chemotherapy efficacy in ER positive breast cancers.…”

“…In the case of MDA-MB-231 and ZR-75-1, respectively 1% non-essential amino acids (Life Technologies, ThermoFisher Scientific, Milan, Italy) and 1% of Na Pyruvate (Lonza, Milan, Italy) were added. MCF10A were cultured as previously described 28 . Cells were cultured at 37 °C with 5% CO 2 in a humidified atmosphere.…”

SLMP53-2 Restores Wild-Type-Like Function to Mutant p53 through Hsp70: Promising Activity in Hepatocellular Carcinoma

“…1.5 × 10 6 HuH-7 cells were seeded in 150 mm dishes and allowed to adhere overnight, followed by 24 h treatment with 28 µM SLMP53-2 or DMSO. ChIP protocol was performed as described [51]. p53 occupancy at the p21 promoter was measured by RT-qPCR (primers are listed in Table S6).…”

Integrated regulatory-metabolic network model reveals critical mechanism and potential targets for Hepatocellular Carcinoma

“…ETV7 is a transcription factor belonging to ETS family, which has been proved to be responsible for the development of different tissues as well as the progression of several cancers, such as HCC (24,25). Due to its translocation function, the overexpression of ETV7 has been associated with tumorigenic transformation and anti-apoptosis by blocking Mys-induced apoptosis pathway (26)(27)(28). Furthermore, there are growing experimental evidences showing that ETV7 also plays a significant role in mTOR signaling pathway by assembling mTOR3 complex, which can stimulate cell proliferation and is not sensitive to rapamycin, a common anti-tumor agent, unlike mTOR1/2 (29).…”