Abstract

Tumor necrosis factor receptor-associated protein 1 (TRAP1) is abnormally expressed in many cancers. In this study, we showed that TRAP1 is aberrantly upregulated in breast tumors compared to control tissues. TRAP1 knockdown downregulates mitochondrial aerobic respiratory, sensitizes cells to lethal stimuli, and inhibited tumor growth in MDA-MB-231 and MCF-7 breast cancer cells in vivo. TRAP1 overexpression, however, enhances the capacity to cope with stress conditions. These evidences suggested that TRAP1 is required for tumorigenesis. We also found that TRAP1 regulates the mitochondrial morphology. Relatively lower TRAP1 levels are associated with the rod-shaped mitochondrial phenotype in invasive and metastatic MDA-MB-231 breast cancer cells; on the contrary, higher TRAP1 levels are associated with the tubular network-shaped mitochondrial phenotype in non-invasive MCF-7 cells. Interestingly, the expression of TRAP1 in human breast cancer specimens inversely correlates with tumor grade. Overexpression of TRAP1 in MDA-MB-231 cells causes mitochondrial fusion, triggers mitochondria to form tubular networks, and suppresses cell migration and invasion in vitro and in vivo. These data link TRAP1-regulated mitochondrial dynamics and function with tumorigenesis of breast cancer and suggested that TRAP1 may therefore be a potential target for breast cancer drug development.

Highlights

  • Breast cancer is one of the most frequently diagnosed cancers in women, comprising 23% of new cancer cases and 14% of all cancer deaths [1]

  • To further determine the importance of Tumor necrosis factor receptor-associated protein 1 (TRAP1) in tumorigenesis, we investigated the effect of TRAP1 knockdown on tumor growth in vivo

  • We demonstrated that TRAP1 is overexpressed in breast cancer

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Summary

Introduction

Breast cancer is one of the most frequently diagnosed cancers in women, comprising 23% of new cancer cases and 14% of all cancer deaths [1]. Treatment of breast cancer is determined by its classification. While targeted therapies such as tamoxifen and trastuzumab benefit patients with ER+ and HER2+ breast cancers [2, 3], the basal phenotype, characterized by the lack of expression of ERα, PR and HER2 (referred to as triple-negative breast cancer), is more difficult to treat and often has a poor prognosis. ER+ and HER+ phenotypes suffer as targeted therapies eventually fail, due to the intrinsic or acquired resistance derived from tumor heterogeneity or genomic instability. This instability includes mutations and alterations in drug transporter proteins, suppression of apoptotic pathways, and altered signal transduction [4]

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