Loss of SIRT4 promotes the self-renewal of Breast Cancer Stem Cells

Abstract

Rationale: It has been proposed that cancer stem/progenitor cells (or tumor-initiating cells, TICs) account for breast cancer initiation and progression. Sirtuins are nicotinamide adenine dinucleotide (NAD+)-dependent class-III histone deacetylases and mediate various basic biological processes, including metabolic homeostasis. However, interplay and cross-regulation among the sirtuin family are not fully understood. As one of the least studied sirtuin family members, the mitochondrial sirtuin SIRT4 is a tumor suppressor gene in various cancers. However, its role in cancer stemness, as well as initiation and progression of breast cancer, remains unknown. Methods: The expression of SIRT4 in breast cancer was analyzed using the TCGA breast cancer database and 3 GSEA data. Normal breast epithelial cells MCF10A and breast cancer cell lines MCF-7, MDA-MB-231, BT549, MDA-MB-468 were used to establish SIRT4 gene knockdown and corresponding overexpression cells. Identified MTT cytotoxicity assays, cell invasion and motility assay, sorting of SP, confocal immunofluorescence microscopy, mouse mammary stem cell analysis, glutamine and glucose production, clonogenic and sphere-formation assay, mass spectrometric metabolomics analysis and ChIP-seq to further explore SIRT4 biological role in breast cancer. Results: We elucidated a novel role for SIRT4 in the negative regulation of mammary gland development and stemness, which is related to the mammary tumorigenesis. We also uncovered an inverse correlation between SIRT4 and SIRT1. Most importantly, SIRT4 negatively regulates SIRT1 expression via repressing glutamine metabolism. Besides, we identified H4K16ac and BRCA1 as new prime targets of SIRT4 in breast cancer. Conclusions: These results demonstrate that SIRT4 exerts its tumor-suppressive activity via modulating SIRT1 expression in breast cancer and provide a novel cross-talk between mitochondrial and nuclear sirtuins.

Research Progress of Sirtuin4 in Cancer

“…The analysis of TCGA and 3 Gene Expression Omnibus (GEO) datasets showed that decreased SIRT4 expression correlated with increased risk of disease progression and poor clinical outcome. Besides, immunoblotting and IHC staining also showed a significant decrease in SIRT4 protein levels in breast tumor tissues ( 83 ). Wang and colleagues found that down-regulation of SIRT4 expression promoted glutamine decomposition, promoted the growth of breast-cancer cells and inhibited their apoptosis.…”

“…SIRT4 deficiency increases the expression of acetyl-histone H3 at lys9 (H3K9ac), acetyl-histone H4 at lys16 (H4K16ac) and stem-cell markers, and down-regulates BRCA1 expression by regulating H4K16ac rather than well-defined H3K9ac. These processes cannot be separated from SIRT1, which regulates the acetylation pattern of histone H4 and regulates stemness through BRCA1 ( 83 ) ( Figure 6 ).…”

CCL16 maintains stem cell-like properties in breast cancer by activating CCR2/GSK3β/β-catenin/OCT4 axis

“…Recent studies have demonstrated that tumor progression and metastasis may be linked to the emergence of cancer stem cells 2 - 5 . However, our current understanding of which factor(s) drive the stemness signaling pathways in breast cancer remains limited even though much progress has occurred in the area of tumor progression 6 - 8 .…”

Progress of Breast Cancer basic research in China

“…Phospholipid scramblase 1 (PLSCR1) enhanced stem cell-like properties through upregulating signal transducer as well as activator of transcription 1 (STAT1) expression in basal-like breast cancer (BLBC) 20 . Additionally, loss of SIRT4 promoted self-renewal and expansion of BCSCs through suppressing glutamine metabolism in mitochondrial and SIRT1-mediated BRCA1 transcription in nucleus, which provided a novel cross-talk between mitochondrial and nuclear sirtuins 21 .…”